ERIC Educational Resources Information Center
Littman, George W., III
1979-01-01
Proper cash flow planning allows a school business administrator to determine the availability of cash for operating expenses, the need for bank loans to cover these expenses, and the availability of idle cash for investment. (Author)
A Conceptual Framework for the Indirect Method of Reporting Net Cash Flow from Operating Activities
ERIC Educational Resources Information Center
Wang, Ting J.
2010-01-01
This paper describes the fundamental concept of the reconciliation behind the indirect method of the statement of cash flows. A conceptual framework is presented to demonstrate how accrual and cash-basis accounting methods relate to each other and to illustrate the concept of reconciling these two accounting methods. The conceptual framework…
Kauer, R T; Silvers, J B
1991-01-01
Hospital managers may find it difficult to admit their investments have been suboptimal, but such investments often lead to poor returns and less future cash. Inappropriate use of free cash flow produces large transaction costs of exit. The relative efficiency of investor-owned and tax-exempt hospitals in the product market for hospital services is examined as the free cash flow theory is used to explore capital-market conditions of hospitals. Hypotheses concerning the current competitive conditions in the industry are set forth, and the implications of free cash flow for risk, capital-market efficiency, and the cost of capital to tax-exempt institution is compared to capital-market norms. PMID:1743965
The FASB explores accounting for future cash flows.
Luecke, R W; Meeting, D T
2001-03-01
The FASB's Statement of Financial Accounting Concepts No. 7, Using Cash Flow Information and Present Value in Accounting Measurements (Statement No. 7), presents the board's views regarding how cash-flow information and present values should be used in accounting for future cash flows when information on fair values is not available. Statement No. 7 presents new concepts regarding how an asset's present value should be calculated and when the interest method of allocation should be used. The FASB proposes a present-value method that takes into account the degree of uncertainty associated with future cash flows among different assets and liabilities. The FASB also suggests that rather than use estimated cash flows (in which a single set of cash flows and a single interest rate is used to reflect the risk associated with an asset or liability), accountants should use expected cash flows (in which all expectations about possible cash flows are used) in calculating present values. PMID:11258273
Back to Basics: Teaching the Statement of Cash Flows
ERIC Educational Resources Information Center
Cecil, H. Wayne; King, Teresa T.; Andrews, Christine P.
2011-01-01
A conceptual foundation for the Statement of Cash Flows based on the ten elements of financial statements provides students with a deep understanding of core accounting concepts. Traditional methods of teaching the statement of cash flows tend to focus on statement preparation rules, masking the effect of business events on the change in cash.…
ERIC Educational Resources Information Center
Brickner, Daniel R.; McCombs, Gary B.
2004-01-01
In this article, the authors provide an instructional resource for presenting the indirect method of the statement of cash flows (SCF) in an introductory financial accounting course. The authors focus primarily on presenting a comprehensive example that illustrates the "why" of SCF preparation and show how journal entries and T-accounts can be…
CEOs say patient deposits improve cash flow.
Anderson, H J
1991-02-20
CEOs say it makes good business sense to require patients to make cash deposits toward their bills prior to admission, because improved cash flow is vital to financially strapped hospitals. But hospitals that require cash deposits should also be aware of the sensitive public relations issues involved, experts caution. PMID:1993531
Unstop the Logjams in Your Cash Flow.
ERIC Educational Resources Information Center
Everett, R. E.
1989-01-01
A cash flow analysis is charting expenditures and revenues against a factor of time. Explains how school systems can, by charting the congruency of revenues and expenditures carefully, develop an investment program to take maximum advantage of a positive cash position. (MLF)
48 CFR 232.072-3 - Cash flow forecasts.
Code of Federal Regulations, 2011 CFR
2011-10-01
... problems. (c) Single or one-time cash flow forecasts are of limited forecasting power. As such, they should... 48 Federal Acquisition Regulations System 3 2011-10-01 2011-10-01 false Cash flow forecasts. 232..., DEPARTMENT OF DEFENSE GENERAL CONTRACTING REQUIREMENTS CONTRACT FINANCING 232.072-3 Cash flow forecasts....
48 CFR 232.072-3 - Cash flow forecasts.
Code of Federal Regulations, 2012 CFR
2012-10-01
... problems. (c) Single or one-time cash flow forecasts are of limited forecasting power. As such, they should... 48 Federal Acquisition Regulations System 3 2012-10-01 2012-10-01 false Cash flow forecasts. 232..., DEPARTMENT OF DEFENSE GENERAL CONTRACTING REQUIREMENTS CONTRACT FINANCING 232.072-3 Cash flow forecasts....
Developing a planning model to estimate future cash flows.
Barenbaum, L; Monahan, T F
1988-03-01
Financial managers are discovering that net income and other traditional measures of cash flow may not provide them with the flexibility needed for comprehensive internal planning and control. By using a discretionary cash flow model, financial managers have a forecasting tool that can help them measure anticipated cash flows, and make better decisions concerning financing alternatives, capital expansion, and performance appraisal. PMID:10302282
48 CFR 232.072-3 - Cash flow forecasts.
Code of Federal Regulations, 2014 CFR
2014-10-01
... problems. (c) Single or one-time cash flow forecasts are of limited forecasting power. As such, they should... 48 Federal Acquisition Regulations System 3 2014-10-01 2014-10-01 false Cash flow forecasts. 232..., DEPARTMENT OF DEFENSE GENERAL CONTRACTING REQUIREMENTS CONTRACT FINANCING 232.072-3 Cash flow forecasts....
48 CFR 232.072-3 - Cash flow forecasts.
Code of Federal Regulations, 2013 CFR
2013-10-01
... problems. (c) Single or one-time cash flow forecasts are of limited forecasting power. As such, they should... 48 Federal Acquisition Regulations System 3 2013-10-01 2013-10-01 false Cash flow forecasts. 232..., DEPARTMENT OF DEFENSE GENERAL CONTRACTING REQUIREMENTS CONTRACT FINANCING 232.072-3 Cash flow forecasts....
The Cash Flow Budget. Part I--Development
ERIC Educational Resources Information Center
Gehm, Rudy
1978-01-01
With the cash flow budget a college store manager can prepare himself and the business office to meet current obligations during periods of cash shortfall. Its development is described and guidelines are offered. (LBH)
FASB's Latest Standard: A Look at the Statement of Cash Flows.
ERIC Educational Resources Information Center
Fischer, Mary; Blythe, Joseph C.
1993-01-01
A discussion of the Financial Accounting Standards Board's new accounting standard No. 117, which concerns colleges and universities as nonprofit organizations, looks at new provisions and reporting requirements. Methods for producing the required cash flow statement are outlined, and the use of cash flow ratios is examined. (MSE)
Fourteen Steps to More Effective Cash Flow Management
ERIC Educational Resources Information Center
Neugebauer, Roger
2004-01-01
Managing cash flow is an incredibly important skill for a center director. Even a center with an annual budget showing a healthy surplus may experience brief periods where funds in the checkbook are insufficient to pay all the bills. To discover how successful directors manage cash flow in tight times, the author surveyed members of the "Exchange…
A Logical Approach to the Statement of Cash Flows
ERIC Educational Resources Information Center
Petro, Fred; Gean, Farrell
2014-01-01
Of the three financial statements in financial reporting, the Statement of Cash Flows (SCF) is perhaps the most challenging. The most difficult aspect of the SCF is in developing an understanding of how previous transactions are finalized in this document. The purpose of this paper is to logically explain the indirect approach of cash flow whereby…
48 CFR 232.072-3 - Cash flow forecasts.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 48 Federal Acquisition Regulations System 3 2010-10-01 2010-10-01 false Cash flow forecasts. 232.072-3 Section 232.072-3 Federal Acquisition Regulations System DEFENSE ACQUISITION REGULATIONS SYSTEM... liquidation of loans; and (8) Estimated amount and timing of cash receipt from other sources. (f)...
ACFAC: a cash flow analysis code for estimating product price from an industrial operation
Delene, J.G.
1980-04-01
A computer code is presented which uses a discountted cash flow methodology to obtain an average product price for an industtrial process. The general discounted cash flow method is discussed. Special code options include multiple treatments of interest during construction and other preoperational costs, investment tax credits, and different methods for tax depreciation of capital assets. Two options for allocating the cost of plant decommissioning are available. The FORTRAN code listing and the computer output for a sample problem are included.
ERIC Educational Resources Information Center
McCue, Michael J.
2007-01-01
Context: National benchmark data for 2002 indicate that large rural for-profit hospitals have a median cash flow margin of 19.5% compared to 9.2% for their nonprofit counterparts. Purpose: This study aims to gain insight regarding the driving factors behind the high cash flow performance of large rural for-profit hospitals. Methods: Using 3 annual…
Infrastructure Analysis Tools: A Focus on Cash Flow Analysis (Presentation)
Melaina, M.; Penev, M.
2012-09-01
NREL has developed and maintains a variety of infrastructure analysis models for the U.S. Department of Energy. Business case analysis has recently been added to this tool set. This presentation focuses on cash flow analysis. Cash flows depend upon infrastructure costs, optimized spatially and temporally, and assumptions about financing and revenue. NREL has incorporated detailed metrics on financing and incentives into the models. Next steps in modeling include continuing to collect feedback on regional/local infrastructure development activities and 'roadmap' dynamics, and incorporating consumer preference assumptions on infrastructure to provide direct feedback between vehicles and station rollout.
Geothermal loan guaranty cash flow model: description and users' manual
Keimig, M.A.; Rosenberg, J.I.; Entingh, D.J.
1980-11-01
This is the users guide for the Geothermal Loan Guaranty Cash Flow Model (GCFM). GCFM is a Fortran code which designs and costs geothermal fields and electric power plants. It contains a financial analysis module which performs life cycle costing analysis taking into account various types of taxes, costs and financial structures. The financial module includes a discounted cash flow feature which calculates a levelized breakeven price for each run. The user's guide contains descriptions of the data requirements and instructions for using the model.
How automation is breaking the cash flow logjam.
Watson, S
1994-06-01
As financially strapped hospitals look for ways to improve their cash flow, they are turning to automation to streamline claims processing and shorten the payment cycle. By using the latest automation tools, hospital business offices are making the most of their limited staff resources. PMID:10141199
Back to Basics: Algebraic Foundations of the Statement of Cash Flows
ERIC Educational Resources Information Center
Joyner, Donald T.; Banatte, Jean-Marie; Dondeti, V. Reddy
2014-01-01
The indirect method for preparing the statement of cash flows, as described in many standard textbooks, involves an item-by-item approach, telling you to add to or subtract from the net income, the increases or decreases in the balance sheet items, such as accounts payable or accounts receivable. Many business students, especially at the…
Modeling banks cash flow behavior in the Federal Reserve system
Booker, J.M.; Drake, R.H.
1992-01-01
Do financial institutions exhibit similar currency flow patterns within the Federal reserve system Certain models indicate that the answer is yes. However, the answer not only depends upon model formation, but also upon the manner in which the raw data is structured. This structuring refers to how the raw data is collapsed, or what level of detail is used in the model. For example, should cash flows be averaged on a yearly basis The choice of granularity becomes crucial in obtaining an affirmative answer to the question. This paper presents the results of various model formations using linear models and principal components, and using various granularities in the data. Other factors involved in the modeling effect include temporal effects, geographic effects, and characteristics of the financial institutions such as institution type (commercial bank, S L, Credit Union, etc.) and size'' (deposits, loans, volume). The results of this study indicate similar currency flow behaviors at more general levels of detail, indicate how varied and different these behaviors can be at finer levels of detail, and indicate which data transformations and covariates are best for model construction.
Modeling banks cash flow behavior in the Federal Reserve system
Booker, J.M.; Drake, R.H.
1992-07-01
Do financial institutions exhibit similar currency flow patterns within the Federal reserve system? Certain models indicate that the answer is yes. However, the answer not only depends upon model formation, but also upon the manner in which the raw data is structured. This structuring refers to how the raw data is collapsed, or what level of detail is used in the model. For example, should cash flows be averaged on a yearly basis? The choice of granularity becomes crucial in obtaining an affirmative answer to the question. This paper presents the results of various model formations using linear models and principal components, and using various granularities in the data. Other factors involved in the modeling effect include temporal effects, geographic effects, and characteristics of the financial institutions such as institution type (commercial bank, S&L, Credit Union, etc.) and ``size`` (deposits, loans, volume). The results of this study indicate similar currency flow behaviors at more general levels of detail, indicate how varied and different these behaviors can be at finer levels of detail, and indicate which data transformations and covariates are best for model construction.
Why Cash Flow Is No Longer for Wimps
ERIC Educational Resources Information Center
Curry, John R.; Hutton, Lyn
2012-01-01
Managing liquidity--a college or university's ability to access cash quickly or to easily convert assets to cash--is an increasingly crucial component of enterprise risk management. Liquidity risks lurk around nearly every corner--in the endowment portfolio, the debt portfolio, and in working-capital management. It also influences students'…
The use of cash flow to analyze financial distress in California hospitals.
McCue, M J
1991-01-01
Previous studies of financial distress have utilized operating margins to measure this outcome. This study examines financial distress from the standpoint of cash flow, which is defined as net income plus depreciation adjusted for accruals. Defining financially distressed hospitals as ones with negative cash flows, the findings of the study show that these hospitals possess a lower occupancy rate, exhibit a slower collection of receivables, and have higher amounts of debt. However, the findings show that it is harder to predict financial distress defined in terms of cash flow than in profitability. PMID:10110408
Hernried, J; Binder, L; Hernried, P
1990-02-23
Cumulative figures of "average medical student indebtedness," although meaningful, do not convey the effect of loan repayments on residents' cash flow, effect on a resident's value system and residency performance, and effect on trends in health care manpower allocation. Using a computer-based cash flow model, a "typical" house officer with $20,000 in undergraduate indebtedness who is training in a less expensive city will realize a $2390 deficit during internship and negative cash flow throughout a 5-year residency. House officers with extreme indebtedness (greater than $80,000) who are training in an expensive metropolitan area would accumulate an overall deficit approaching $75,000 or more, in excess of their undergraduate indebtedness, during a 5-year residency program. Effects of these findings on residency education and health care manpower issues, along with potential solutions for alleviating residents' cash flow problems, are discussed. PMID:2299783
An Experiment of Student Understanding of Accruals versus Cash Flows
ERIC Educational Resources Information Center
Miranda-Lopez, Jose Eduardo; Nichols, Linda M.
2007-01-01
The concepts of both accrual accounting and cash basis accounting need to be thoroughly understood by accounting graduates as they enter the workplace. In making decisions, both managers and investors often may need to make adjustments from one basis to the other. But do students really understand these concepts? This study uses an experimental…
Off-line compatible electronic cash method and system
Kravitz, David W.; Gemmell, Peter S.; Brickell, Ernest F.
1998-01-01
An off-line electronic cash system having an electronic coin, a bank B, a payee S, and a user U with an account at the bank B as well as a user password z.sub.u,i, has a method for performing an electronic cash transfer. An electronic coin is withdrawn from the bank B by the user U and an electronic record of the electronic coin is stored by the bank B. The coin is paid to the payee S by the user U. The payee S deposits the coin with the bank B. A determination is made that the coin is spent and the record of the coin is deleted by the bank B. A further deposit of the same coin after the record is deleted is determined. Additionally, a determination is made which user U originally withdrew the coin after deleting the record. To perform these operations a key pair is generated by the user, including public and secret signature keys. The public signature key along with a user password z.sub.u,i and a withdrawal amount are sent to the bank B by the user U. In response, the bank B sends a coin to the user U signed by the secret key of the bankindicating the value of the coin and the public key of the user U. The payee S transmits a challenge counter to the user U prior to receiving the coin.
Off-line compatible electronic cash method and system
Kravitz, D.W.; Gemmell, P.S.; Brickell, E.F.
1998-11-03
An off-line electronic cash system having an electronic coin, a bank B, a payee S, and a user U with an account at the bank B as well as a user password z{sub u,i}, has a method for performing an electronic cash transfer. An electronic coin is withdrawn from the bank B by the user U and an electronic record of the electronic coin is stored by the bank B. The coin is paid to the payee S by the user U. The payee S deposits the coin with the bank B. A determination is made that the coin is spent and the record of the coin is deleted by the bank B. A further deposit of the same coin after the record is deleted is determined. Additionally, a determination is made which user U originally withdrew the coin after deleting the record. To perform these operations a key pair is generated by the user, including public and secret signature keys. The public signature key along with a user password z{sub u,i} and a withdrawal amount are sent to the bank B by the user U. In response, the bank B sends a coin to the user U signed by the secret key of the bank indicating the value of the coin and the public key of the user U. The payee S transmits a challenge counter to the user U prior to receiving the coin. 16 figs.
Giving credit its due in the group practice setting. How credit cards can improve cash flow.
Pear, M J
1991-01-01
The health care industry is moving toward more patient service, and one aspect of service often overlooked is billing, writes Marcia Pear. Some practice managers believe credit cards aren't cost effective. In reality, they can actually accelerate cash flow and allow patients to resolve financial obligations sooner. PMID:10114605
Pratt, William R
2010-01-01
Hospitals are facing substantial financial and economic pressure as a result of health plan payment restructuring, unfunded mandates, and other factors. This article analyzes the relationship between free cash flow (FCF) and hospital efficiency given these financial challenges. Data from 270 California hospitals were used to estimate a stochastic frontier model of hospital cost efficiency that explicitly takes into account outpatient heterogeneity. The findings indicate that hospital FCF is significantly linked to firm efficiency/inefficiency. The results indicate that higher positive cash flows are related to lower cost inefficiency, but higher negative cash flows are related to higher cost inefficiency. Thus, cash flows not only impact the ability of hospitals to meet current liabilities, they are also related to the ability of the hospitals to use resources effectively. PMID:20973372
Consumer-driven health plans: latest challenge to practices' cash flow.
Hajny, Tom
2007-01-01
CDHPs are here to stay. Employers welcome CDHPs because they drive costs away from themselves and into the hands of both consumers and provides. The consumer will make medical purchase decisions tempered by personal economic considerations. The providers are left to figure it all out with the hope their cash flow, cost budgets, and customer service will not be negatively impacted. It will not be easy. Practices must become educated on how CDHPs work, become knowledgeable about specific HSA scenarios in their market, develop optimum processes and procedures, and train staff. PMID:17494494
41 CFR 301-51.101 - Which payment methods are considered the equivalent of cash?
Code of Federal Regulations, 2012 CFR
2012-07-01
... considered the equivalent of cash and you must comply with the rules in 41 CFR 102-118.50 that limit the use of cash for such purposes. (a) Personal credit cards; (b) Cash withdrawals obtained from an ATM...
41 CFR 301-51.101 - Which payment methods are considered the equivalent of cash?
Code of Federal Regulations, 2014 CFR
2014-07-01
... considered the equivalent of cash and you must comply with the rules in 41 CFR 102-118.50 that limit the use of cash for such purposes. (a) Personal credit cards; (b) Cash withdrawals obtained from an ATM...
41 CFR 301-51.101 - Which payment methods are considered the equivalent of cash?
Code of Federal Regulations, 2013 CFR
2013-07-01
... equivalent of cash and you must comply with the rules in 41 CFR 102-118.50 that limit the use of cash for such purposes. (a) Personal credit cards; (b) Cash withdrawals obtained from an ATM using a...
41 CFR 301-51.101 - Which payment methods are considered the equivalent of cash?
Code of Federal Regulations, 2011 CFR
2011-07-01
... considered the equivalent of cash and you must comply with the rules in 41 CFR 102-118.50 that limit the use of cash for such purposes. (a) Personal credit cards; (b) Cash withdrawals obtained from an ATM...
41 CFR 301-51.101 - Which payment methods are considered the equivalent of cash?
Code of Federal Regulations, 2010 CFR
2010-07-01
... considered the equivalent of cash and you must comply with the rules in 41 CFR 102-118.50 that limit the use of cash for such purposes. (a) Personal credit cards; (b) Cash withdrawals obtained from an ATM...
Mitchell, G.
2015-04-02
This presentation discusses the differences between the original Vehicle and Infrastructure Cash-Flow Evaluation (VICE) Model and the revamped version, VICE 2.0. The enhanced tool can now help assess projects to acquire vehicles and infrastructure, or to acquire vehicles only.
ERIC Educational Resources Information Center
Davis, Michelle R.
2008-01-01
This article reports that the crisis besetting U.S. and world financial markets is hitting school districts hard, as they struggle to float the bonds needed for capital projects, borrow money to ensure cash flow, and get access to investment funds locked up in troubled institutions. Some schools districts depend heavily on borrowed money to pay…
ERIC Educational Resources Information Center
Fischer, Mary L.; Ostrom, John S.
1982-01-01
Elements of an effective management program for colleges and universities are examined. Five basic purposes of an effective program of cash management are identified: developing accurate cash projections, managing cash receipts, controlling cash disbursements, establishing sound banking relationships, and investing funds. It is suggested that all…
Schmutz, Bryan P; Santerre, Rexford E
2013-02-01
Unlike the pharmaceutical industry, no empirical research has focused on the factors influencing research and development (R&D) spending in the medical device industry. To fill that gap, this study examines how R&D spending is influenced by prior year cash flow and corporate market value using multiple regression analysis and a panel data set of medical device companies over the period 1962-2008. The empirical findings suggest that the elasticities of R&D spending with respect to cash flow and corporate market value equal 0.58 and 0.31, respectively. Moreover, based upon these estimates, simulations show that the recently enacted excise tax on medical devices, taken alone, will reduce R&D spending by approximately $4 billion and thereby lead to a minimum loss of $20 billion worth of human life years over the first 10 years of its enactment. PMID:23303706
Chatterjee, Bishu; Sharp, Peter A.
2006-07-15
Electric transmission and other rate cases use a form of the discounted cash flow model with a single long-term growth rate to estimate rates of return on equity. It cannot incorporate information about the appropriate time horizon for which analysts' estimates of earnings growth have predictive powers. Only a non-constant growth model can explicitly recognize the importance of the time horizon in an ROE calculation. (author)
Lexa, Frank James; Berlin, Jonathan W
2005-03-01
In this article, the authors cover tools for financial modeling. Commonly used time lines and cash flow diagrams are discussed. Commonly used but limited terms such as payback and breakeven are introduced. The important topics of the time value of money and discount rates are introduced to lay the foundation for their use in modeling and in more advanced metrics such as the internal rate of return. Finally, the authors broach the more sophisticated topic of net present value. PMID:17411805
ERIC Educational Resources Information Center
Boyles, William W.
1975-01-01
In 1973, Ronald G. Lykins presented a model for cash management and analysed its benefits for Ohio University. This paper attempts to expand on the previous method by providing answers to questions raised by the Lykins methods by a series of simple algebraic formulas. Both methods are based on two premises: (1) all cash over which the business…
Gonzales, John
2015-04-02
Presentation by Senior Engineer John Gonzales on Evaluating Investments in Natural Gas Vehicles and Infrastructure for Your Fleet using the Vehicle Infrastructure Cash-flow Estimation (VICE) 2.0 model.
Copiello, Sergio
2016-01-01
The Discounted Cash Flow method is a long since well-known tool to assess the feasibility of investment projects, as the background which shapes a broad range of techniques, from the Cost-Benefit Analysis up to the Life-Cycle Cost Analysis. Its rationale lies in the comparison of deferred values, only once they have been discounted back to the present. The DCF variant proposed here fits into a specific application field. It is well-suited to the evaluations required in order to structure equitable transactions under the umbrella of Public-Private Partnership. •The discount rate relies upon the concept of expected return on equity, instead than on those of weighted average cost of capital, although the latter is the most common reference within the scope of real estate investment valuation.•Given a feasible project, whose Net Present Value is more than satisfactory, we aim to identify the amount of the additional burdens that could be charged to the project, under the condition of keeping the same economically viable.•The DCF variant essentially deals with an optimization problem, which can be solved by means of simple one-shot equations, derived from financial mathematics, or through iterative calculations if additional constraints must be considered. PMID:27054095
Copiello, Sergio
2016-01-01
The Discounted Cash Flow method is a long since well-known tool to assess the feasibility of investment projects, as the background which shapes a broad range of techniques, from the Cost-Benefit Analysis up to the Life-Cycle Cost Analysis. Its rationale lies in the comparison of deferred values, only once they have been discounted back to the present. The DCF variant proposed here fits into a specific application field. It is well-suited to the evaluations required in order to structure equitable transactions under the umbrella of Public-Private Partnership. • The discount rate relies upon the concept of expected return on equity, instead than on those of weighted average cost of capital, although the latter is the most common reference within the scope of real estate investment valuation. • Given a feasible project, whose Net Present Value is more than satisfactory, we aim to identify the amount of the additional burdens that could be charged to the project, under the condition of keeping the same economically viable. • The DCF variant essentially deals with an optimization problem, which can be solved by means of simple one-shot equations, derived from financial mathematics, or through iterative calculations if additional constraints must be considered. PMID:27054095
NASA Astrophysics Data System (ADS)
Shi, Larry; Carbunar, Bogdan; Sion, Radu
We introduce a novel conditional e-cash protocol allowing future anonymous cashing of bank-issued e-money only upon the satisfaction of an agreed-upon public condition. Payers are able to remunerate payees for services that depend on future, yet to be determined outcomes of events. Once payment complete, any double-spending attempt by the payer will reveal its identity; no double-spending by the payee is possible. Payers can not be linked to payees or to ongoing or past transactions. The flow of cash within the system is thus both correct and anonymous. We discuss several applications of conditional e-cash including online trading of financial securities, prediction markets, and betting systems.
ERIC Educational Resources Information Center
Chen, Jeng-Hong
2008-01-01
This study demonstrates that a popular graphing calculator among students, TI-83 Plus, has a powerful function to draw the NPV profile and find the accurate multiple IRRs for a project with non-conventional cash flows. However, finance textbooks or related supplementary materials do not provide students instructions for this part. The detailed…
Cash efficiency for bank branches.
Cabello, Julia García
2013-01-01
Bank liquidity management has become a major issue during the financial crisis as liquidity shortages have intensified and have put pressure on banks to diversity and improve their liquidity sources. While a significant strand of the literature concentrates on wholesale liquidity generation and on the alternative to deposit funding, the management of an inventory of cash holdings within the banks' branches is also a relevant issue as any significant improvement in cash management at the bank distribution channels may have a positive effect in reducing liquidity tensions. In this paper, we propose a simple programme of cash efficiency for the banks' branches, very easy to implement, which conform to a set of instructions to be imposed from the bank to their branches. This model proves to significantly reduce cash holdings at branches thereby providing efficiency improvements in liquidity management. The methodology we propose is based on the definition of some stochastic processes combined with renewal processes, which capture the random elements of the cash flow, before applying suitable optimization programmes to all the costs involved in cash movements. The classical issue of the Transaction Demand for the Cash and some aspects of Inventory Theory are also present. Mathematics Subject Classification (2000) C02, C60, E50. PMID:24010026
ERIC Educational Resources Information Center
Woodall, Michael V.; Spoonhour, Laura T.
1994-01-01
A South Carolina school district changed food service from a financial loss to a profit. Recommends that food service managers record meal revenues and expenses when they occur and study the profitability of each program. Selling meal tickets in advance provides some control over the number of students who purchase meals. (MLF)
Net Operating Working Capital, Capital Budgeting, and Cash Budgets: A Teaching Example
ERIC Educational Resources Information Center
Tuner, James A.
2016-01-01
Many introductory finance texts present information on the capital budgeting process, including estimation of project cash flows. Typically, estimation of project cash flows begins with a calculation of net income. Getting from net income to cash flows requires accounting for non-cash items such as depreciation. Also important is the effect of…
Reducing Crime by Eliminating Cash.
ERIC Educational Resources Information Center
Warwick, David R.
Ending the use of cash in the United States can provide substantial social and economic gain while requiring only modest levels of investment. One primary benefit is the reduction of cash-related crimes. Because most street crime is committed to obtain cash or uses cash as a transaction medium, elimination of cash will dramatically reduce crime.…
Numerical methods for turbulent flow
NASA Astrophysics Data System (ADS)
Turner, James C., Jr.
1988-09-01
It has generally become accepted that the Navier-Strokes equations predict the dynamic behavior of turbulent as well as laminar flows of a fluid at a point in space away form a discontinuity such as a shock wave. Turbulence is also closely related to the phenomena of non-uniqueness of solutions of the Navier-Strokes equations. These second order, nonlinear partial differential equations can be solved analytically for only a few simple flows. Turbulent flow fields are much to complex to lend themselves to these few analytical methods. Numerical methods, therefore, offer the only possibility of achieving a solution of turbulent flow equations. In spite of recent advances in computer technology, the direct solution, by discrete methods, of the Navier-Strokes equations for turbulent flow fields is today, and in the foreseeable future, impossible. Thus the only economically feasible way to solve practical turbulent flow problems numerically is to use statistically averaged equations governing mean-flow quantities. The objective is to study some recent developments relating to the use of numerical methods to study turbulent flow.
Flow analysis system and method
NASA Technical Reports Server (NTRS)
Hill, Wayne S. (Inventor); Barck, Bruce N. (Inventor)
1998-01-01
A non-invasive flow analysis system and method wherein a sensor, such as an acoustic sensor, is coupled to a conduit for transmitting a signal which varies depending on the characteristics of the flow in the conduit. The signal is amplified and there is a filter, responsive to the sensor signal, and tuned to pass a narrow band of frequencies proximate the resonant frequency of the sensor. A demodulator generates an amplitude envelope of the filtered signal and a number of flow indicator quantities are calculated based on variations in amplitude of the amplitude envelope. A neural network, or its equivalent, is then used to determine the flow rate of the flow in the conduit based on the flow indicator quantities.
28 CFR 345.72 - Cash bonus or cash award.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 28 Judicial Administration 2 2013-07-01 2013-07-01 false Cash bonus or cash award. 345.72 Section 345.72 Judicial Administration FEDERAL PRISON INDUSTRIES, INC., DEPARTMENT OF JUSTICE FEDERAL PRISON INDUSTRIES (FPI) INMATE WORK PROGRAMS Awards Program § 345.72 Cash bonus or cash award. An inmate worker...
28 CFR 345.72 - Cash bonus or cash award.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 28 Judicial Administration 2 2011-07-01 2011-07-01 false Cash bonus or cash award. 345.72 Section 345.72 Judicial Administration FEDERAL PRISON INDUSTRIES, INC., DEPARTMENT OF JUSTICE FEDERAL PRISON INDUSTRIES (FPI) INMATE WORK PROGRAMS Awards Program § 345.72 Cash bonus or cash award. An inmate worker...
28 CFR 345.72 - Cash bonus or cash award.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 28 Judicial Administration 2 2012-07-01 2012-07-01 false Cash bonus or cash award. 345.72 Section 345.72 Judicial Administration FEDERAL PRISON INDUSTRIES, INC., DEPARTMENT OF JUSTICE FEDERAL PRISON INDUSTRIES (FPI) INMATE WORK PROGRAMS Awards Program § 345.72 Cash bonus or cash award. An inmate worker...
28 CFR 345.72 - Cash bonus or cash award.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 28 Judicial Administration 2 2014-07-01 2014-07-01 false Cash bonus or cash award. 345.72 Section 345.72 Judicial Administration FEDERAL PRISON INDUSTRIES, INC., DEPARTMENT OF JUSTICE FEDERAL PRISON INDUSTRIES (FPI) INMATE WORK PROGRAMS Awards Program § 345.72 Cash bonus or cash award. An inmate worker...
Techniques for Improving Cash Management.
ERIC Educational Resources Information Center
Lykins, Ronald G.
1973-01-01
This article deals with several techniques for regulating cash inflow and outflow and investing surplus cash for short periods of time. The techniques are: (1) consolidating checking accounts, (2) determining surplus cash by examining bank balances in conjunction with the cash book, (3) selecting a minimum bank balance, (4) investing a greater…
Vortex methods for separated flows
NASA Technical Reports Server (NTRS)
Spalart, Philippe R.
1988-01-01
The numerical solution of the Euler or Navier-Stokes equations by Lagrangian vortex methods is discussed. The mathematical background is presented and includes the relationship with traditional point-vortex studies, convergence to smooth solutions of the Euler equations, and the essential differences between two and three-dimensional cases. The difficulties in extending the method to viscous or compressible flows are explained. Two-dimensional flows around bluff bodies are emphasized. Robustness of the method and the assessment of accuracy, vortex-core profiles, time-marching schemes, numerical dissipation, and efficient programming are treated. Operation counts for unbounded and periodic flows are given, and two algorithms designed to speed up the calculations are described.
Vortex methods for separated flows
NASA Technical Reports Server (NTRS)
Spalart, Philippe R.
1988-01-01
The numerical solution of the Euler or Navier-Stokes equations by Lagrangian vortex methods is discussed. The mathematical background is presented in an elementary fashion and includes the relationship with traditional point-vortex studies, the convergence to smooth solutions of the Euler equations, and the essential differences between two- and three-dimensional cases. The difficulties in extending the method to viscous or compressible flows are explained. The overlap with the excellent review articles available is kept to a minimum and more emphasis is placed on the area of expertise, namely two-dimensional flows around bluff bodies. When solid walls are present, complete mathematical models are not available and a more heuristic attitude must be adopted. The imposition of inviscid and viscous boundary conditions without conformal mappings or image vortices and the creation of vorticity along solid walls are examined in detail. Methods for boundary-layer treatment and the question of the Kutta condition are discussed. Practical aspects and tips helpful in creating a method that really works are explained. The topics include the robustness of the method and the assessment of accuracy, vortex-core profiles, timemarching schemes, numerical dissipation, and efficient programming. Calculations of flows past streamlined or bluff bodies are used as examples when appropriate.
Cash Flow Smoothing for Schools.
ERIC Educational Resources Information Center
David, Remigius
The model developed in this article is intended to help the finance manager of a tuition-supported school make calculated investments of surplus moneys. It is designed to make funds available to pay salaries and bills when needed and to add interest in increasingly larger amounts to the available funds of the school. It assumes that the finance…
ERIC Educational Resources Information Center
Beutler, Ivan F.; Mason, Jerald W.
1987-01-01
Distribution for a formalized budget variable is reported for a representative sample of families. Most households reported little, if any, formal planning. Compared to informal planners, formal planners are more likely to have the following characteristics: younger, more years of education, two-spouse households, and high circumstantial demands.…
Computerized cash management: the new frontier.
Grimmelman, F J
1979-01-01
Because cash management in a hospital is more complicated today than it was ten years ago, the finanical manager needs a computerized cash management system to help assess cash resources and control cash demands. PMID:10242146
Krylov methods for compressible flows
NASA Technical Reports Server (NTRS)
Tidriri, M. D.
1995-01-01
We investigate the application of Krylov methods to compressible flows, and the effect of implicit boundary conditions on the implicit solution of nonlinear problems. Two defect-correction procedures, namely, approximate factorization (AF) for structured grids and ILU/GMRES for general grids, are considered. Also considered here are Newton-Krylov matrix-free methods that we combined with the use of mixed discretization schemes in the implicitly defined Jacobian and its preconditioner. Numerical experiments that show the performance of our approaches are then presented.
ERIC Educational Resources Information Center
Zelenak, Mel J.
1977-01-01
Results of an attitude questionnaire designed to examine businesspersons' attitudes towards the cash discount provision in the Fair Credit Billing Act indicate that businesspersons are divided in their attitudes towards the provision, and contradict theories that all merchants would oppose the provision. (TA)
Code of Federal Regulations, 2010 CFR
2010-07-01
... funds that an institution receives from the Secretary under the just-in-time payment method. (b) Excess...; and (2) Providing funds to the institution under the reimbursement payment method or cash monitoring payment method described in § 668.163(d) and (e), respectively. (Authority: 20 U.S.C. 1094)...
Overview of multifluid-flow-calculation methods
Stewart, H.B.
1981-01-01
Two categories of numerical methods which may be useful in multiphase flow research are discussed. The first category includes methods which are specifically intended for accurate computation of discontinuities, such as the method of characteristics, particle-in-cell method, flux-corrected transport, and random choice methods. Methods in this category could be applied to research on rocket exhaust plumes and interior ballistics. The second category includes methods for smooth, subsonic flows, such as fractional step methods, semi-implicit method, and methods which treat convection implicitly. The subsonic flow methods could be of interest for ice flows. (LCL)
Insertable fluid flow passage bridgepiece and method
Jones, Daniel O.
2000-01-01
A fluid flow passage bridgepiece for insertion into an open-face fluid flow channel of a fluid flow plate is provided. The bridgepiece provides a sealed passage from a columnar fluid flow manifold to the flow channel, thereby preventing undesirable leakage into and out of the columnar fluid flow manifold. When deployed in the various fluid flow plates that are used in a Proton Exchange Membrane (PEM) fuel cell, bridgepieces of this invention prevent mixing of reactant gases, leakage of coolant or humidification water, and occlusion of the fluid flow channel by gasket material. The invention also provides a fluid flow plate assembly including an insertable bridgepiece, a fluid flow plate adapted for use with an insertable bridgepiece, and a method of manufacturing a fluid flow plate with an insertable fluid flow passage bridgepiece.
Gas flow meter and method for measuring gas flow rate
Robertson, Eric P.
2006-08-01
A gas flow rate meter includes an upstream line and two chambers having substantially equal, fixed volumes. An adjustable valve may direct the gas flow through the upstream line to either of the two chambers. A pressure monitoring device may be configured to prompt valve adjustments, directing the gas flow to an alternate chamber each time a pre-set pressure in the upstream line is reached. A method of measuring the gas flow rate measures the time required for the pressure in the upstream line to reach the pre-set pressure. The volume of the chamber and upstream line are known and fixed, thus the time required for the increase in pressure may be used to determine the flow rate of the gas. Another method of measuring the gas flow rate uses two pressure measurements of a fixed volume, taken at different times, to determine the flow rate of the gas.
What Happened to the Cash? Effective Cash Control.
ERIC Educational Resources Information Center
Horrigan, William J.
This paper examines a variety of cash-generating school operations--student activity accounts, athletics, athletic user fees, other user fees, concessions, and cafeterias--and identifies areas where controls are needed. Specific techniques for ensuring effective cash controls are outlined. Internal-audit procedures are suggested that address the…
NASA Astrophysics Data System (ADS)
Torizumi, Y.; Hirayama, N.; Maeda, T.
1983-01-01
Flow characteristics of a compressible gas flow through an orifice are investigated experimentally at pressure ratios below the regulation values of JIS and ASME. For practical mass flow measurements, a theoretical method of mass flow estimations is extended using one-dimensional flow theory and experimental data. Using the method, the accuracy of mass flow measurements with orifice meters is about + or 1% in the Reynolds number range of turbulent flows and also in supercritical flows. Tables of the product of flow coefficient and expansion factor are obtained by the method at various diameter ratios, pressure ratios, and specific heats.
Effect of flow fluctuations and nonflow on elliptic flow methods
Ollitrault, Jean-Yves; Poskanzer, Arthur M.; Voloshin, Sergei A.
2009-04-16
We discuss how the different estimates of elliptic flow are influenced by flow fluctuations and nonflow effects. It is explained why the event-plane method yields estimates between the two-particle correlation methods and the multiparticle correlation methods. It is argued that nonflow effects and fluctuations cannot be disentangled without other assumptions. However, we provide equations where, with reasonable assumptions about fluctuations and nonflow, all measured values of elliptic flow converge to a unique mean v_2,PP elliptic flow in the participant plane and, with a Gaussian assumption on eccentricity fluctuations, can be converted to the mean v_2,RP in the reaction plane. Thus, the 20percent spread in observed elliptic flow measurements from different analysis methods is no longer mysterious.
Chaturvedi, Sarika; Upadhyay, Sourabh; De Costa, Ayesha; Raven, Joanna
2015-01-01
Objectives To study implementation of partograph use to monitor labour in facilities providing the JSY (Janani Suraksha Yojana) cash transfer programme for facility births in India by determining (1) adherence to partograph use, (2) staff abilities at partograph use and (3) staff responsiveness to the policy on partograph use. Design A mixed methods study using Carroll's framework for implementation fidelity. Methods include (1) obstetric case record review, (2) a vignette-based survey among nurse midwives and (3) interviews with staff. Setting Routine use of the partograph is recommended to monitor progress of labour in most low-and middle-income countries (LMICs), including India, although currently available evidence in this regard is insufficient. This study was conducted in the context of the highly successful JSY programme in three districts of Madhya Pradesh province. Participants 73 different level JSY programme facilities participated in the record review, 233 nurse midwives at these facilities participated in the vignette survey and a total of 11 doctors and midwives participated in the interviews. Results The partograph was used in 6% of the 1466 records reviewed. The staff obtained a median score of 1.08 (maximum of 10) at competence in plotting a partograph. Three themes emerged from the qualitative data: (1) partographs are used rarely and retrospectively; (2) training does not support correct use of the partograph; and (3) partographs can be useful but are not feasible. Conclusions Implementation fidelity of partograph use in the JSY programme is low. Successful implementation of the partograph can result in improved quality of care in the JSY programme only if potential moderators to its adherence, such as training, supervision, staff ‘buy in’ and practice environment are addressed so that staff find a conducive practice environment in which to use the partograph and women find it beneficial to present early in labour. PMID:25922094
Natural Elements Method for Free Surface Flow
NASA Astrophysics Data System (ADS)
Darbani, M.; Ouahsine, A.; Villon, P.
2009-09-01
The Natural Element Method (NEM) is used to simulate a 2D shallow water flow in presence of free surface and a varying bathymetry. This meshless method used a fully Lagrangian formulation and natural neighbors, which remain a very striking problem related the boundary conditions. The method was succefully used to simulate dam-break flows by solving the fully nonlinear Shallow Water Equations (SWE) and by using an implicit scheme under a transient flow and the Coriolis effect.
On the Methods to Measure Powder Flow.
Tan, Geoffrey; Morton, David A V; Larson, Ian
2015-01-01
The flow of powders can often play a critical role in the manufacturing of pharmaceutical products. Many of these processes require good, consistent and predictable flow of powders to ensure continuous production of pharmaceutical dosages and to ensure their quality. Therefore, the flow of powders is of paramount importance to the pharmaceutical industry and thus the measuring and evaluating of powder flow is of utmost importance. At present, there are numerous methods in which the flow of powders can be measured. However, due to the complex and environment-dependent nature of powders, no one method exists that is capable of providing a complete picture of the behaviour of powders under dynamic conditions. Some of the most commonly applied methods to measure the flow of powders include: density indices, such as the Carr index and Hausner ratio, powder avalanching, the angle of repose (AOR), flow through an orifice, powder rheometry and shear cell testing. PMID:26446467
A survey of aftbody flow prediction methods
NASA Technical Reports Server (NTRS)
Putnam, L. E.; Mace, J.
1981-01-01
A survey of computational methods used in the calculation of nozzle aftbody flows is presented. One class of methods reviewed are those which patch together solutions for the inviscid, boundary layer, and plume flow regions. The second class of methods reviewed are those which computationally solve the Navier Stokes equations over nozzle aftbodies with jet exhaust flow. Computed results from the methods are compared with experiment. Advantages and disadvantages of the various methods are discussed along with opportunities for further development of these methods.
A novel microfluidic flow focusing method
Jiang, Hai; Weng, Xuan; Li, Dongqing
2014-01-01
A new microfluidic method that allows hydrodynamic focusing in a microchannel with two sheath flows is demonstrated. The microchannel network consists of a T-shaped main channel and two T-shaped branch channels. The flows of the sample stream and the sheath streams in the microchannel are generated by electroosmotic flow-induced pressure gradients. In comparison with other flow focusing methods, this novel method does not expose the sample to electrical field, and does not need any external pumps, tubing, and valves. PMID:25538810
Spectral methods for inviscid, compressible flows
NASA Technical Reports Server (NTRS)
Hussaini, M. Y.; Salas, M. D.; Zang, T. A.
1983-01-01
Report developments in the application of spectral methods to two dimensional compressible flows are reviewed. A brief introduction to spectral methods -- their history and especially their implementation -- is provided. The stress is on those techniques relevant to transonic flow computation. The spectral multigrid iterative methods are discussed with application to the transonic full potential equation. Discontinuous solutions of the Euler equations are considered. The key element is the shock fitting technique which is briefly explained.
Computational methods for ideal compressible flow
NASA Technical Reports Server (NTRS)
Vanleer, B.
1983-01-01
Conservative dissipative difference schemes for computing one dimensional flow are introduced, and the recognition and representation of flow discontinuities are discussed. Multidimensional methods are outlined. Second order finite volume schemes are introduced. Conversion of difference schemes for a single linear convection equation into schemes for the hyperbolic system of the nonlinear conservation laws of ideal compressible flow is explained. Approximate Riemann solvers are presented. Monotone initial value interpolation; and limiters, switches, and artificial dissipation are considered.
Solving functional flow equations with pseudospectral methods
NASA Astrophysics Data System (ADS)
Borchardt, J.; Knorr, B.
2016-07-01
We apply pseudospectral methods to integrate functional flow equations with high accuracy, extending earlier work on functional fixed point equations [J. Borchardt and B. Knorr, Phys. Rev. D 91, 105011 (2015)]. The advantages of our method are illustrated with the help of two classes of models: first, to make contact with literature, we investigate flows of the O (N ) model in three dimensions, for N =1 , 4 and in the large N limit. For the case of a fractal dimension, d =2.4 , and N =1 , we follow the flow along a separatrix from a multicritical fixed point to the Wilson-Fisher fixed point over almost 13 orders of magnitude. As a second example, we consider flows of bounded quantum-mechanical potentials, which can be considered as a toy model for Higgs inflation. Such flows pose substantial numerical difficulties, and represent a perfect test bed to exemplify the power of pseudospectral methods.
Improved Panel-Method/Potential-Flow Code
NASA Technical Reports Server (NTRS)
Ashby, Dale L.
1991-01-01
Panel code PMARC (Panel Method Ames Research Center) numerically simulates flow field around complex three-dimensional bodies, such as complete aircraft models. Based on potential-flow theory. Written in FORTRAN 77, with exception of namelist extension used for input. Structure facilitates addition of new features to code and tailoring of code to specific problems and computer hardware constraints.
Computational methods for unsteady transonic flows
NASA Technical Reports Server (NTRS)
Edwards, John W.; Thomas, James L.
1987-01-01
Computational methods for unsteady transonic flows are surveyed with emphasis upon applications to aeroelastic analysis and flutter prediction. Computational difficulty is discussed with respect to type of unsteady flow; attached, mixed (attached/separated) and separated. Significant early computations of shock motions, aileron buzz and periodic oscillations are discussed. The maturation of computational methods towards the capability of treating complete vehicles with reasonable computational resources is noted and a survey of recent comparisons with experimental results is compiled. The importance of mixed attached and separated flow modeling for aeroelastic analysis is discussed and recent calculations of periodic aerodynamic oscillations for an 18 percent thick circular arc airfoil are given.
Computational methods for unsteady transonic flows
NASA Technical Reports Server (NTRS)
Edwards, John W.; Thomas, J. L.
1987-01-01
Computational methods for unsteady transonic flows are surveyed with emphasis on prediction. Computational difficulty is discussed with respect to type of unsteady flow; attached, mixed (attached/separated) and separated. Significant early computations of shock motions, aileron buzz and periodic oscillations are discussed. The maturation of computational methods towards the capability of treating complete vehicles with reasonable computational resources is noted and a survey of recent comparisons with experimental results is compiled. The importance of mixed attached and separated flow modeling for aeroelastic analysis is discussed, and recent calculations of periodic aerodynamic oscillations for an 18 percent thick circular arc airfoil are given.
Tomographic methods in flow diagnostics
NASA Technical Reports Server (NTRS)
Decker, Arthur J.
1993-01-01
This report presents a viewpoint of tomography that should be well adapted to currently available optical measurement technology as well as the needs of computational and experimental fluid dynamists. The goals in mind are to record data with the fastest optical array sensors; process the data with the fastest parallel processing technology available for small computers; and generate results for both experimental and theoretical data. An in-depth example treats interferometric data as it might be recorded in an aeronautics test facility, but the results are applicable whenever fluid properties are to be measured or applied from projections of those properties. The paper discusses both computed and neural net calibration tomography. The report also contains an overview of key definitions and computational methods, key references, computational problems such as ill-posedness, artifacts, missing data, and some possible and current research topics.
An exact inverse method for subsonic flows
NASA Technical Reports Server (NTRS)
Daripa, Prabir
1988-01-01
A new inverse method for the aerodynamic design of airfoils is presented for subcritical flows. The pressure distribution in this method can be prescribed as a function of the arclength of the still unknown body. It is shown that this inverse problem is mathematically equivalent to solving only one nonlinear boundary value problem subject to known Dirichlet data on the boundary.
Program allows Ill. providers to cash in Medicaid receivables.
Nemes, J
1991-12-01
The Illinois Health Facilities Authority soon will start a $100 million commercial paper program that will use a pool of Medicaid receivables from hospitals and nursing homes to back the issue. The plan is designed to provide money to improve cash flow at facilities facing long delays in reimbursement for Medicaid patients. PMID:10115262
Semiempirical methods for computing turbulent flows
NASA Technical Reports Server (NTRS)
Belov, I. A.; Ginzburg, I. P.
1986-01-01
Two semiempirical theories which provide a basis for determining the turbulent friction and heat exchange near a wall are presented: (1) the Prandtl-Karman theory, and (2) the theory utilizing an equation for the energy of turbulent pulsations. A comparison is made between exact numerical methods and approximate integral methods for computing the turbulent boundary layers in the presence of pressure, blowing, or suction gradients. Using the turbulent flow around a plate as an example, it is shown that, when computing turbulent flows with external turbulence, it is preferable to construct a turbulence model based on the equation for energy of turbulent pulsations.
Method and apparatus for controlling fluid flow
Miller, J.R.
1980-06-27
A method and apparatus for precisely controlling the rate (and hence amount) of fluid flow are given. The controlled flow rate is finely adjustable, can be extremely small (on the order of microliter-atmospheres per second), can be adjusted to zero (flow stopped), and is stable to better than 1% with time. The dead volume of the valve can be made arbitrarily small, in fact essentially zero. The valve employs no wearing mechanical parts (including springs, stems, or seals). The valve is finely adjustable, has a flow rate dynamic range of many decades, can be made compatible with any fluid, and is suitable for incorporation into an open or closed loop servo-control system.
Unstructured grid methods for compressible flows
NASA Technical Reports Server (NTRS)
Morgan, K.; Peraire, J.; Peiro, J.
1992-01-01
The implementation of the finite element method on unstructured triangular grids is described and the development of centered finite element schemes for the solution of the compressible Euler equation on general triangular and tetrahedral grids is discussed. Explicit and implicit Lax-Wendroff type methods and a method based upon the use of explicit multistep timestepping are considered. In the latter case, the convergence behavior of the method is accelerated by the incorporation of a fully unstructured multigrid procedure. The advancing front method for generating unstructured grids of triangles and tetrahedra is described and the application of adaptive mesh techniques to both steady and transient flow analysis is illustrated.
Method for identifying anomalous terrestrial heat flows
Del Grande, Nancy Kerr
1977-01-25
A method for locating and mapping the magnitude and extent of terrestrial heat-flow anomalies from 5 to 50 times average with a tenfold improved sensitivity over orthodox applications of aerial temperature-sensing surveys as used for geothermal reconnaissance. The method remotely senses surface temperature anomalies such as occur from geothermal resources or oxidizing ore bodies by: measuring the spectral, spatial, statistical, thermal, and temporal features characterizing infrared radiation emitted by natural terrestrial surfaces; deriving from these measurements the true surface temperature with uncertainties as small as 0.05 to 0.5 K; removing effects related to natural temperature variations of topographic, hydrologic, or meteoric origin, the surface composition, detector noise, and atmospheric conditions; factoring out the ambient normal-surface temperature for non-thermally enhanced areas surveyed under otherwise identical environmental conditions; distinguishing significant residual temperature enhancements characteristic of anomalous heat flows and mapping the extent and magnitude of anomalous heat flows where they occur.
Tobe, Chris
2003-10-01
Certain strategies can offer not-for-profit hospitals potentially greater investment yields while maintaining stability and principal safety. Treasury inflation-indexed securities can offer good returns, low volatility, and inflation protection. "Enhanced cash" strategies offer liquidity and help to preserve capital. Stable value "wrappers" allow hospitals to pursue higher-yielding fixed-income securities without an increase in volatility. PMID:14560584
Converting accounts receivable into cash.
Folk, M D; Roest, P R
1995-09-01
In recent years, increasing numbers of healthcare providers have converted their accounts receivable into cash through a process called securitization. This practice has gained popularity because it provides a means to raise capital necessary to healthcare organizations. Although securitization transactions can be complex, they may provide increased financial flexibility to providers as they prepare for continuing change in the healthcare industry. PMID:10145096
Hydraulic flow visualization method and apparatus
Karidis, P.G.
1984-01-01
An apparatus and method for visualizing liquid flow. Pulses of gas bubbles are introduced into a liquid flow stream and a strobe light is operated at a frequency related to the frequency of the gas pulses to shine on the bubbles as they pass through the liquid stream. The gas pulses pass through a probe body having a valve element, and a reciprocating valve stem passes through the probe body to operate the valve element. A stem actuating device comprises a slidable reciprocating member, operated by a crank arm. The actuated member is adjustable to adjust the amount of the valve opening during each pulse.
Cash transfer in Brazil and nutritional outcomes: a systematic review
Martins, Ana Paula Bortoletto; Canella, Daniela Silva; Baraldi, Larissa Galastri; Monteiro, Carlos Augusto
2013-01-01
OBJECTIVE To analyze the influence of conditional cash transfer programs on diet and nutrition outcomes among beneficiary families in Brazil. METHODS A systematic review of literature was carried out with original evaluation studies conducted in Brazil, including all types of clinical trials and observational studies. The search was conducted in PubMed, Scopus, Web of Science and LILACS databases for papers published since 1990. The studies were analyzed according to the program evaluated, participants, study design, location, principal conclusions, confounding factors and methodological limitations. They were classified according to outcomes (nutritional status, dietary intake and food security) and level of evidence for the association with conditional cash transfer programs (adequacy or plausibility). RESULTS We found 1,412 non-duplicated papers. Fifteen met the eligibility criteria and twelve evaluated the Bolsa Família program. Five plausibility studies and two adequacy analyses indicated a positive influence of conditional cash transfer programs on nutritional status of the beneficiary children. The conditional cash transfer programs influence on dietary intake was analyzed in one population-based adequacy study and three cross-sectionals plausibility researches in different municipalities. All of them indicated that beneficiaries had higher food intake than non-beneficiaries. The three cross-sectional plausibility analyses suggest a positive influence of conditional cash transfer programs on the food security of the beneficiaries. The main methodological limitations found were using cross-sectional analysis and difficulties in data collection, small sample sizes and limitations of the instruments used. CONCLUSIONS The few studies found indicated a positive association between Brazilian conditional cash transfer programs and improvements in the recipients' diet and nutrition. Greater efforts to widen and qualify evaluations are needed in order to assess more
Flow coating apparatus and method of coating
Hanumanthu, Ramasubrahmaniam; Neyman, Patrick; MacDonald, Niles; Brophy, Brenor; Kopczynski, Kevin; Nair, Wood
2014-03-11
Disclosed is a flow coating apparatus, comprising a slot that can dispense a coating material in an approximately uniform manner along a distribution blade that increases uniformity by means of surface tension and transfers the uniform flow of coating material onto an inclined substrate such as for example glass, solar panels, windows or part of an electronic display. Also disclosed is a method of flow coating a substrate using the apparatus such that the substrate is positioned correctly relative to the distribution blade, a pre-wetting step is completed where both the blade and substrate are completed wetted with a pre-wet solution prior to dispensing of the coating material onto the distribution blade from the slot and hence onto the substrate. Thereafter the substrate is removed from the distribution blade and allowed to dry, thereby forming a coating.
On Numerical Methods For Hypersonic Turbulent Flows
NASA Astrophysics Data System (ADS)
Yee, H. C.; Sjogreen, B.; Shu, C. W.; Wang, W.; Magin, T.; Hadjadj, A.
2011-05-01
Proper control of numerical dissipation in numerical methods beyond the standard shock-capturing dissipation at discontinuities is an essential element for accurate and stable simulation of hypersonic turbulent flows, including combustion, and thermal and chemical nonequilibrium flows. Unlike rapidly developing shock interaction flows, turbulence computations involve long time integrations. Improper control of numerical dissipation from one time step to another would be compounded over time, resulting in the smearing of turbulent fluctuations to an unrecognizable form. Hypersonic turbulent flows around re- entry space vehicles involve mixed steady strong shocks and turbulence with unsteady shocklets that pose added computational challenges. Stiffness of the source terms and material mixing in combustion pose yet other types of numerical challenges. A low dissipative high order well- balanced scheme, which can preserve certain non-trivial steady solutions of the governing equations exactly, may help minimize some of these difficulties. For stiff reactions it is well known that the wrong propagation speed of discontinuities occurs due to the under-resolved numerical solutions in both space and time. Schemes to improve the wrong propagation speed of discontinuities for systems of stiff reacting flows remain a challenge for algorithm development. Some of the recent algorithm developments for direct numerical simulations (DNS) and large eddy simulations (LES) for the subject physics, including the aforementioned numerical challenges, will be discussed.
Method of fabricating a flow device
Hale, Robert L.
1978-01-01
This invention is a novel method for fabricating leak-tight tubular articles which have an interior flow channel whose contour must conform very closely with design specifications but which are composed of metal which tends to warp if welded. The method comprises designing two longitudinal half-sections of the article, the half-sections being contoured internally to cooperatively form the desired flow passageway. Each half-section is designed with a pair of opposed side flanges extending between the end flanges and integral therewith. The half-sections are positioned with their various flanges in confronting relation and with elongated metal gaskets extending between the confronting flanges for the length of the array. The gaskets are a deformable metal which is fusion-weldable to the end flanges. The mating side flanges are joined mechanically to deform the gaskets and provide a longitudinally sealed assembly. The portions of the end flanges contiguous with the ends of the gaskets then are welded to provide localized end welds which incorporate ends of the gaskets, thus transversely sealing the assembly. This method of fabrication provides leak-tight articles having the desired precisely contoured flow channels, whereas various conventional methods have been found unsatisfactory.
Lattice Boltzmann method and channel flow
NASA Astrophysics Data System (ADS)
Stensholt, Sigvat; Mongstad Hope, Sigmund
2016-07-01
Lattice Boltzmann methods are presented at an introductory level with a focus on fairly simple simulations that can be used to test and illustrate the model’s capabilities. Two scenarios are presented. The first is a simple laminar flow in a straight channel driven by a pressure gradient (Poiseuille flow). The second is a more complex, including a wedge where Moffatt vortices may be induced if the wedge is deep enough. Simulations of the Poiseuille flow scenario accurately capture the theoretical velocity profile. The experiment shows the location of the fluid-wall boundary and the effects viscosity has on the velocity and convergence time. The numerical capabilities of the lattice Boltzmann model are tested further by simulating the more complex Moffatt vortex scenario. The method reproduces with high accuracy the theoretical predction that Moffat vortices will not form in a wedge if the vertex angle exceeds 146°. Practical issues limitations of the lattice Boltzmann method are discussed. In particular the accuracy of the bounce-back boundary condition is first order dependent on the grid resolution.
2014-01-01
Introduction Haryana was the first state in India to launch a conditional cash transfer (CCT) scheme in 1994. Initially it targeted all disadvantaged girls but was revised in 2005 to restrict it to second girl children of all groups. The benefit which accrued at girl attaining 18 years and subject to conditionalities of being fully immunized, studying till class 10 and remaining unmarried, was increased from about US$ 500 to US$ 2000. Using a mixed methods approach, we evaluated the implementation and possible impact of these two schemes. Methods A survey was conducted among 200 randomly selected respondents of Ballabgarh Block in Haryana to assess their perceptions of girl children and related schemes. A cohort of births during this period was assembled from population database of 28 villages in this block and changes in sex ratio at birth and in immunization coverage at one year of age among boys and girls was measured. Education levels and mean age at marriage of daughters were compared with daughters-in-law from outside Haryana. In-depth interviews were conducted among district level implementers of these schemes to assess their perceptions of programs’ implementation and impact. These were analyzed using a thematic approach. Results The perceptions of girls as a liability and poor (9% to 15%) awareness of the schemes was noted. The cohort analysis showed that while there has been an improvement in the indicators studied, these were similar to those seen among the control groups. Qualitative analysis identified a “conspiracy of silence” - an underplaying of the pervasiveness of the problem coupled with a passive implementation of the program and a clash between political culture of giving subsidies and a bureaucratic approach that imposed many conditionalities and documentary needs for availing of benefits. Conclusion The apparent lack of impact on the societal mindset calls for a revision in the current approach of addressing a social issue by a purely
Computational methods for vortex dominated compressible flows
NASA Technical Reports Server (NTRS)
Murman, Earll M.
1987-01-01
The principal objectives were to: understand the mechanisms by which Euler equation computations model leading edge vortex flows; understand the vortical and shock wave structures that may exist for different wing shapes, angles of incidence, and Mach numbers; and compare calculations with experiments in order to ascertain the limitations and advantages of Euler equation models. The initial approach utilized the cell centered finite volume Jameson scheme. The final calculation utilized a cell vertex finite volume method on an unstructured grid. Both methods used Runge-Kutta four stage schemes for integrating the equations. The principal findings are briefly summarized.
A Continuous Method for Gene Flow
Palczewski, Michal; Beerli, Peter
2013-01-01
Most modern population genetics inference methods are based on the coalescence framework. Methods that allow estimating parameters of structured populations commonly insert migration events into the genealogies. For these methods the calculation of the coalescence probability density of a genealogy requires a product over all time periods between events. Data sets that contain populations with high rates of gene flow among them require an enormous number of calculations. A new method, transition probability-structured coalescence (TPSC), replaces the discrete migration events with probability statements. Because the speed of calculation is independent of the amount of gene flow, this method allows calculating the coalescence densities efficiently. The current implementation of TPSC uses an approximation simplifying the interaction among lineages. Simulations and coverage comparisons of TPSC vs. MIGRATE show that TPSC allows estimation of high migration rates more precisely, but because of the approximation the estimation of low migration rates is biased. The implementation of TPSC into programs that calculate quantities on phylogenetic tree structures is straightforward, so the TPSC approach will facilitate more general inferences in many computer programs. PMID:23666937
Flow cytometric detection method for DNA samples
Nasarabadi,Shanavaz; Langlois, Richard G.; Venkateswaran, Kodumudi S.
2011-07-05
Disclosed herein are two methods for rapid multiplex analysis to determine the presence and identity of target DNA sequences within a DNA sample. Both methods use reporting DNA sequences, e.g., modified conventional Taqman.RTM. probes, to combine multiplex PCR amplification with microsphere-based hybridization using flow cytometry means of detection. Real-time PCR detection can also be incorporated. The first method uses a cyanine dye, such as, Cy3.TM., as the reporter linked to the 5' end of a reporting DNA sequence. The second method positions a reporter dye, e.g., FAM.TM. on the 3' end of the reporting DNA sequence and a quencher dye, e.g., TAMRA.TM., on the 5' end.
Flow cytometric detection method for DNA samples
Nasarabadi, Shanavaz; Langlois, Richard G.; Venkateswaran, Kodumudi S.
2006-08-01
Disclosed herein are two methods for rapid multiplex analysis to determine the presence and identity of target DNA sequences within a DNA sample. Both methods use reporting DNA sequences, e.g., modified conventional Taqman.RTM. probes, to combine multiplex PCR amplification with microsphere-based hybridization using flow cytometry means of detection. Real-time PCR detection can also be incorporated. The first method uses a cyanine dye, such as, Cy3.TM., as the reporter linked to the 5' end of a reporting DNA sequence. The second method positions a reporter dye, e.g., FAM, on the 3' end of the reporting DNA sequence and a quencher dye, e.g., TAMRA, on the 5' end.
Radioisotope method of compound flow analysis
NASA Astrophysics Data System (ADS)
Petryka, Leszek; Zych, Marcin; Hanus, Robert; Sobota, Jerzy; Vlasak, Pavel; Malczewska, Beata
2015-05-01
The paper presents gamma radiation application to analysis of a multicomponent or multiphase flow. Such information as a selected component content in the mixture transported through pipe is crucial in many industrial or laboratory installations. Properly selected sealed radioactive source and collimators, deliver the photon beam, penetrating cross section of the flow. Detectors mounted at opposite to the source side of the pipe, allow recording of digital signals representing composition of the stream. In the present development of electronics, detectors and computer software, a significant progress in know-how of this field may be observed. The paper describes application of this method to optimization and control of hydrotransport of solid particles and propose monitoring facilitating prevent of a pipe clogging or dangerous oscillations.
Integrated business office can boost cash flow.
Moore, R E
1992-03-01
Management of patient accounts traditionally has treated billing and collections as separate functions, with staff members working accounts alphabetically by patient. In an integrated business office, however, staff members are trained in both billing and collections and are specialized according to payers. The advantages of a payer-specific design include more efficient contact with major payer groups and a better trained, more flexible staff. PMID:10145598
Immersed boundary methods for viscoelastic particulate flows
NASA Astrophysics Data System (ADS)
Krishnan, Sreenath; Shaqfeh, Eric; Iaccarino, Gianluca
2015-11-01
Viscoelastic particulate suspensions play key roles in many energy applications. Our goal is to develop a simulation-based tool for engineering such suspensions. This study is concerned with fully resolved simulations, wherein all flow scales associated with the particle motion are resolved. The present effort is based on Immersed Boundary methods, in which the domain grids do not conform to particle geometry. In this approach, the conservation of momentum equations, which include both Newtonian and non-Newtonian stresses, are solved over the entire domain including the region occupied by the particles. The particles are defined on a separate Lagrangian mesh that is free to move over an underlying Eulerian grid. The development of an immersed boundary forcing technique for moving bodies within an unstructured-mesh, massively parallel, non-Newtonian flow solver is thus developed and described. The presentation will focus on the numerical algorithm and measures taken to enable efficient parallelization and transfer of information between the underlying fluid grid and the particle mesh. Several validation test cases will be presented including sedimentation under orthogonal shear - a key flow in drilling muds and fracking fluids.
A Filtering Method For Gravitationally Stratified Flows
Gatti-Bono, Caroline; Colella, Phillip
2005-04-25
Gravity waves arise in gravitationally stratified compressible flows at low Mach and Froude numbers. These waves can have a negligible influence on the overall dynamics of the fluid but, for numerical methods where the acoustic waves are treated implicitly, they impose a significant restriction on the time step. A way to alleviate this restriction is to filter out the modes corresponding to the fastest gravity waves so that a larger time step can be used. This paper presents a filtering strategy of the fully compressible equations based on normal mode analysis that is used throughout the simulation to compute the fast dynamics and that is able to damp only fast gravity modes.
Singularity embedding method in potential flow calculations
NASA Technical Reports Server (NTRS)
Jou, W. H.; Huynh, H.
1982-01-01
The so-called H-type mesh is used in a finite-element (or finite-volume) calculation of the potential flow past an airfoil. Due to coordinate singularity at the leading edge, a special singular trial function is used for the elements neighboring the leading edge. The results using the special singular elements are compared to those using the regular elements. It is found that the unreasonable pressure distribution obtained by the latter is removed by the embedding of the singular element. Suggestions to extend the present method to transonic cases are given.
Date attachable offline electronic cash scheme.
Fan, Chun-I; Sun, Wei-Zhe; Hau, Hoi-Tung
2014-01-01
Electronic cash (e-cash) is definitely one of the most popular research topics in the e-commerce field. It is very important that e-cash be able to hold the anonymity and accuracy in order to preserve the privacy and rights of customers. There are two types of e-cash in general, which are online e-cash and offline e-cash. Both systems have their own pros and cons and they can be used to construct various applications. In this paper, we pioneer to propose a provably secure and efficient offline e-cash scheme with date attachability based on the blind signature technique, where expiration date and deposit date can be embedded in an e-cash simultaneously. With the help of expiration date, the bank can manage the huge database much more easily against unlimited growth, and the deposit date cannot be forged so that users are able to calculate the amount of interests they can receive in the future correctly. Furthermore, we offer security analysis and formal proofs for all essential properties of offline e-cash, which are anonymity control, unforgeability, conditional-traceability, and no-swindling. PMID:24982931
Date Attachable Offline Electronic Cash Scheme
Sun, Wei-Zhe; Hau, Hoi-Tung
2014-01-01
Electronic cash (e-cash) is definitely one of the most popular research topics in the e-commerce field. It is very important that e-cash be able to hold the anonymity and accuracy in order to preserve the privacy and rights of customers. There are two types of e-cash in general, which are online e-cash and offline e-cash. Both systems have their own pros and cons and they can be used to construct various applications. In this paper, we pioneer to propose a provably secure and efficient offline e-cash scheme with date attachability based on the blind signature technique, where expiration date and deposit date can be embedded in an e-cash simultaneously. With the help of expiration date, the bank can manage the huge database much more easily against unlimited growth, and the deposit date cannot be forged so that users are able to calculate the amount of interests they can receive in the future correctly. Furthermore, we offer security analysis and formal proofs for all essential properties of offline e-cash, which are anonymity control, unforgeability, conditional-traceability, and no-swindling. PMID:24982931
Finance theory and hospital cash balances.
Rivenson, Howard L; Smith, Dean G
2013-01-01
Competing financial theories have been offered to understand hospitals' cash holding with scant recent evidence. Using data from a national sample of 608 not-for-profit hospitals, we find support for the trade-off theory which posits targeted cash balances. We do not find support for the financial hierarchy theory which posits a preference for use of cash to pay for capital investments. Findings apply to holdings of cash and marketable securities, but not board-designated funds where no model provided meaningful explanatory power. PMID:23614264
Transonic Flow Computations Using Nonlinear Potential Methods
NASA Technical Reports Server (NTRS)
Holst, Terry L.; Kwak, Dochan (Technical Monitor)
2000-01-01
This presentation describes the state of transonic flow simulation using nonlinear potential methods for external aerodynamic applications. The presentation begins with a review of the various potential equation forms (with emphasis on the full potential equation) and includes a discussion of pertinent mathematical characteristics and all derivation assumptions. Impact of the derivation assumptions on simulation accuracy, especially with respect to shock wave capture, is discussed. Key characteristics of all numerical algorithm types used for solving nonlinear potential equations, including steady, unsteady, space marching, and design methods, are described. Both spatial discretization and iteration scheme characteristics are examined. Numerical results for various aerodynamic applications are included throughout the presentation to highlight key discussion points. The presentation ends with concluding remarks and recommendations for future work. Overall. nonlinear potential solvers are efficient, highly developed and routinely used in the aerodynamic design environment for cruise conditions. Published by Elsevier Science Ltd. All rights reserved.
An extended Lagrangian method for subsonic flows
NASA Technical Reports Server (NTRS)
Liou, Meng-Sing; Loh, Ching Y.
1992-01-01
It is well known that fluid motion can be specified by either the Eulerian of Lagrangian description. Most of Computational Fluid Dynamics (CFD) developments over the last three decades have been based on the Eulerian description and considerable progress has been made. In particular, the upwind methods, inspired and guided by the work of Gudonov, have met with many successes in dealing with complex flows, especially where discontinuities exist. However, this shock capturing property has proven to be accurate only when the discontinuity is aligned with one of the grid lines since most upwind methods are strictly formulated in 1-D framework and only formally extended to multi-dimensions. Consequently, the attractive property of crisp resolution of these discontinuities is lost and research on genuine multi-dimensional approach has just been undertaken by several leading researchers. Nevertheless they are still based on the Eulerian description.
Posting to Cash Record Book from Cash Proof Forms. Student Manual and Instructor's Manual.
ERIC Educational Resources Information Center
McElveen, Peggy C.
Supporting performance objective 40 of the V-TECS (Vocational-Technical Education Consortium of States) Secretarial Catalog, both a set of student materials and an instructor's manual on posting to the cash record book from cash proof forms are included in this packet, which is one of a series. The student materials include five cash sales reports…
Solution of plane cascade flow using improved surface singularity methods
NASA Technical Reports Server (NTRS)
Mcfarland, E. R.
1981-01-01
A solution method has been developed for calculating compressible inviscid flow through a linear cascade of arbitrary blade shapes. The method uses advanced surface singularity formulations which were adapted from those found in current external flow analyses. The resulting solution technique provides a fast flexible calculation for flows through turbomachinery blade rows. The solution method and some examples of the method's capabilities are presented.
Flow "Fine" Synthesis: High Yielding and Selective Organic Synthesis by Flow Methods.
Kobayashi, Shū
2016-02-18
The concept of flow "fine" synthesis, that is, high yielding and selective organic synthesis by flow methods, is described. Some examples of flow "fine" synthesis of natural products and APIs are discussed. Flow methods have several advantages over batch methods in terms of environmental compatibility, efficiency, and safety. However, synthesis by flow methods is more difficult than synthesis by batch methods. Indeed, it has been considered that synthesis by flow methods can be applicable for the production of simple gasses but that it is difficult to apply to the synthesis of complex molecules such as natural products and APIs. Therefore, organic synthesis of such complex molecules has been conducted by batch methods. On the other hand, syntheses and reactions that attain high yields and high selectivities by flow methods are increasingly reported. Flow methods are leading candidates for the next generation of manufacturing methods that can mitigate environmental concerns toward sustainable society. PMID:26337828
Flow “Fine” Synthesis: High Yielding and Selective Organic Synthesis by Flow Methods
2015-01-01
Abstract The concept of flow “fine” synthesis, that is, high yielding and selective organic synthesis by flow methods, is described. Some examples of flow “fine” synthesis of natural products and APIs are discussed. Flow methods have several advantages over batch methods in terms of environmental compatibility, efficiency, and safety. However, synthesis by flow methods is more difficult than synthesis by batch methods. Indeed, it has been considered that synthesis by flow methods can be applicable for the production of simple gasses but that it is difficult to apply to the synthesis of complex molecules such as natural products and APIs. Therefore, organic synthesis of such complex molecules has been conducted by batch methods. On the other hand, syntheses and reactions that attain high yields and high selectivities by flow methods are increasingly reported. Flow methods are leading candidates for the next generation of manufacturing methods that can mitigate environmental concerns toward sustainable society. PMID:26337828
Calculation of transonic flows using an extended integral equation method
NASA Technical Reports Server (NTRS)
Nixon, D.
1976-01-01
An extended integral equation method for transonic flows is developed. In the extended integral equation method velocities in the flow field are calculated in addition to values on the aerofoil surface, in contrast with the less accurate 'standard' integral equation method in which only surface velocities are calculated. The results obtained for aerofoils in subcritical flow and in supercritical flow when shock waves are present compare satisfactorily with the results of recent finite difference methods.
Nuclear reactor flow control method and apparatus
Church, John P.
1993-01-01
Method and apparatus for improving coolant flow in a nuclear reactor during accident as well as nominal conditions. The reactor has a plurality of fuel elements in sleeves and a plenum above the fuel and through which the sleeves penetrate. Holes are provided in the sleeve so that coolant from the plenum can enter the sleeve and cool the fuel. The number and size of the holes are varied from sleeve to sleeve with the number and size of holes being greater for sleeves toward the center of the core and less for sleeves toward the periphery of the core. Preferably the holes are all the same diameter and arranged in rows and columns, the rows starting from the bottom of every sleeve and fewer rows in peripheral sleeves and more rows in the central sleeves.
Nuclear reactor flow control method and apparatus
Church, J.P.
1993-03-30
Method and apparatus for improving coolant flow in a nuclear reactor during accident as well as nominal conditions. The reactor has a plurality of fuel elements in sleeves and a plenum above the fuel and through which the sleeves penetrate. Holes are provided in the sleeve so that coolant from the plenum can enter the sleeve and cool the fuel. The number and size of the holes are varied from sleeve to sleeve with the number and size of holes being greater for sleeves toward the center of the core and less for sleeves toward the periphery of the core. Preferably the holes are all the same diameter and arranged in rows and columns, the rows starting from the bottom of every sleeve and fewer rows in peripheral sleeves and more rows in the central sleeves.
Method and Apparatus for Measuring Fluid Flow
NASA Technical Reports Server (NTRS)
Arndt, G. Dickey (Inventor); Nguyen, Thanh X. (Inventor); Carl, James R. (Inventor)
1997-01-01
Method and apparatus for making measurements on fluids related to their complex permeability are disclosed. A microwave probe is provided for exposure to the fluids. The probe can be non-intrusive or can also be positioned at the location where measurements are to be made. The impedance of the probe is determined. in part. by the complex dielectric constant of the fluids at the probe. A radio frequency signal is transmitted to the probe and the reflected signal is phase and amplitude detected at a rapid rate for the purpose of identifying the fluids. Multiple probes may be selectively positioned to monitor the behavior of the fluids including their flow rate. Fluids may be identified as between two or more different fluids as well as multiple phases of the same fluid based on differences between their complex permittivities.
Lessons about Cash and Manager Priorities
ERIC Educational Resources Information Center
Mong, Donald
2013-01-01
Experienced managers know that cash affects virtually every aspect of a company's strategy and operations. Business students and new managers, however, sometimes lose sight of the importance of cash amidst the details of accrual-based accounting courses, formula-based finance courses, and production-based management courses. We therefore use…
Code of Federal Regulations, 2010 CFR
2010-01-01
... Banking FEDERAL RESERVE SYSTEM (CONTINUED) BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM CREDIT BY...; cancellation or liquidation—(1) Full cash payment. A creditor shall obtain full cash payment for customer... additional payment period. (4) Cancellation; liquidation; minimum amount. A creditor shall promptly cancel...
23 CFR 140.612 - Cash management.
Code of Federal Regulations, 2014 CFR
2014-04-01
... 23 Highways 1 2014-04-01 2014-04-01 false Cash management. 140.612 Section 140.612 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PAYMENT PROCEDURES REIMBURSEMENT Reimbursement for Bond Issue Projects § 140.612 Cash management. By July 1 of each year the SHA will...
23 CFR 140.612 - Cash management.
Code of Federal Regulations, 2013 CFR
2013-04-01
... 23 Highways 1 2013-04-01 2013-04-01 false Cash management. 140.612 Section 140.612 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PAYMENT PROCEDURES REIMBURSEMENT Reimbursement for Bond Issue Projects § 140.612 Cash management. By July 1 of each year the SHA will...
23 CFR 140.612 - Cash management.
Code of Federal Regulations, 2010 CFR
2010-04-01
... 23 Highways 1 2010-04-01 2010-04-01 false Cash management. 140.612 Section 140.612 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PAYMENT PROCEDURES REIMBURSEMENT Reimbursement for Bond Issue Projects § 140.612 Cash management. By July 1 of each year the SHA will...
23 CFR 140.612 - Cash management.
Code of Federal Regulations, 2012 CFR
2012-04-01
... 23 Highways 1 2012-04-01 2012-04-01 false Cash management. 140.612 Section 140.612 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PAYMENT PROCEDURES REIMBURSEMENT Reimbursement for Bond Issue Projects § 140.612 Cash management. By July 1 of each year the SHA will...
23 CFR 140.612 - Cash management.
Code of Federal Regulations, 2011 CFR
2011-04-01
... 23 Highways 1 2011-04-01 2011-04-01 false Cash management. 140.612 Section 140.612 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PAYMENT PROCEDURES REIMBURSEMENT Reimbursement for Bond Issue Projects § 140.612 Cash management. By July 1 of each year the SHA will...
Cash Management/Data Matching. Training Guide.
ERIC Educational Resources Information Center
Office of Student Financial Assistance (ED), Washington, DC.
This training guide for financial aid staff explains the process of direct loan reconciliation and suggests appropriate cash management accounting practices. Chapter 1 explains the importance of cash management, the role of data matching, and reviews basic reconciliation concepts and terms and direct loan reporting requirements. Chapter 2 reviews…
Code of Federal Regulations, 2011 CFR
2011-01-01
... customer as part of a covered option transaction; and (4) Use an escrow agreement in lieu of the cash, cash... issue an escrow agreement and the creditor independently verifies that the appropriate escrow agreement... to be delivered to a person authorized to issue an escrow agreement, the creditor verifies that...
School District Cash Management. Program Audit.
ERIC Educational Resources Information Center
New York State Legislative Commission on Expenditure Review, Albany.
New York State law permits school districts to invest cash not immediately needed for district operation and also specifies the kinds of investments that may be made in order to ensure the safety and liquidity of public funds. This audit examines cash management and investment practices in New York state's financially independent school districts.…
Method and device for measuring fluid flow
Atherton, Richard; Marinkovich, Phillip S.; Spadaro, Peter R.; Stout, J. Wilson
1976-11-23
This invention is a fluid flow measuring device for determining the coolant flow at the entrance to a specific nuclear reactor fuel region. The device comprises a plurality of venturis having the upstream inlet and throat pressure of each respectively manifolded together to provide one static pressure signal for each region monitored. The device provides accurate flow measurement with low pressure losses and uniform entrance and discharge flow distribution.
Review - Computational methods for internal flows with emphasis on turbomachinery
NASA Technical Reports Server (NTRS)
Mcnally, W. D.; Sockol, P. M.
1985-01-01
Current computational methods for analyzing flows in turbomachinery and other related internal propulsion components are presented. The methods are divided into two classes. The inviscid methods deal specifically with turbomachinery applications. Viscous methods, deal with generalized duct flows as well as flows in turbomachinery passages. Inviscid methods are categorized into the potential, stream function, and Euler approaches. Viscous methods are treated in terms of parabolic, partially parabolic, and elliptic procedures. Various grids used in association with these procedures are also discussed.
Computational methods for internal flows with emphasis on turbomachinery
NASA Technical Reports Server (NTRS)
Mcnally, W. D.; Sockol, P. M.
1981-01-01
Current computational methods for analyzing flows in turbomachinery and other related internal propulsion components are presented. The methods are divided into two classes. The inviscid methods deal specifically with turbomachinery applications. Viscous methods, deal with generalized duct flows as well as flows in turbomachinery passages. Inviscid methods are categorized into the potential, stream function, and Euler aproaches. Viscous methods are treated in terms of parabolic, partially parabolic, and elliptic procedures. Various grids used in association with these procedures are also discussed.
Method and apparatus for measuring flow velocity using matched filters
Raptis, Apostolos C.
1983-01-01
An apparatus and method for measuring the flow velocities of individual phase flow components of a multiphase flow utilizes matched filters. Signals arising from flow noise disturbance are extracted from the flow, at upstream and downstream locations. The signals are processed through pairs of matched filters which are matched to the flow disturbance frequency characteristics of the phase flow component to be measured. The processed signals are then cross-correlated to determine the transit delay time of the phase flow component between sensing positions.
Method and apparatus for measuring flow velocity using matched filters
Raptis, A.C.
1983-09-06
An apparatus and method for measuring the flow velocities of individual phase flow components of a multiphase flow utilizes matched filters. Signals arising from flow noise disturbance are extracted from the flow, at upstream and downstream locations. The signals are processed through pairs of matched filters which are matched to the flow disturbance frequency characteristics of the phase flow component to be measured. The processed signals are then cross-correlated to determine the transit delay time of the phase flow component between sensing positions. 8 figs.
Ocular Blood Flow Autoregulation Mechanisms and Methods
Luo, Xue; Shen, Yu-meng; Jiang, Meng-nan; Lou, Xiang-feng; Shen, Yin
2015-01-01
The main function of ocular blood flow is to supply sufficient oxygen and nutrients to the eye. Local blood vessels resistance regulates overall blood distribution to the eye and can vary rapidly over time depending on ocular need. Under normal conditions, the relation between blood flow and perfusion pressure in the eye is autoregulated. Basically, autoregulation is a capacity to maintain a relatively constant level of blood flow in the presence of changes in ocular perfusion pressure and varied metabolic demand. In addition, ocular blood flow dysregulation has been demonstrated as an independent risk factor to many ocular diseases. For instance, ocular perfusion pressure plays key role in the progression of retinopathy such as glaucoma and diabetic retinopathy. In this review, different direct and indirect techniques to measure ocular blood flow and the effect of myogenic and neurogenic mechanisms on ocular blood flow are discussed. Moreover, ocular blood flow regulation in ocular disease will be described. PMID:26576295
Microfluidic devices and methods for integrated flow cytometry
Srivastava, Nimisha; Singh, Anup K.
2011-08-16
Microfluidic devices and methods for flow cytometry are described. In described examples, various sample handling and preparation steps may be carried out within a same microfluidic device as flow cytometry steps. A combination of imaging and flow cytometry is described. In some examples, spiral microchannels serve as incubation chambers. Examples of automated sample handling and flow cytometry are described.
Method and Apparatus for Measuring Fluid Flow
NASA Technical Reports Server (NTRS)
Arndt, G. Dickey (Inventor); Nguyen, Than X. (Inventor); Carl, James R. (Inventor)
1995-01-01
The invention is a method and apparatus for monitoring the presence, concentration, and the movement of fluids. It is based on utilizing electromagnetic measurements of the complex permittivity of the fluids for detecting and monitoring the fluid. More particularly the apparatus uses one or more microwave probes which are placed at the locations where the measurements are to be made. A radio frequency signal is transmitted to the probe and the reflected signal is phase and amplitude detected at a rapid rate for the purpose of identifying the fluids, based on their dielectric constant at the probe. The apparatus can be used for multiple purposes including measures of flow rates, turbulence, dispersion, fluid identification, and changes in flow conditions of multiple fluids or multiple states of a single fluid in a flowline or a holding container. The apparatus includes a probe consisting of two electrical conductors separated by an insulator. A radio frequency signal is communicated to the probe and is reflected back from the portion of the probe exposed to the fluid. The radio frequency signal also provides a reference signal. An oscillator generates a second signal which combined with each of the reference signal and the reflected signal to produce signals of lower frequencies to facilitate filtering and amplifying those signals. The two signals are then mixed in a detector to produce an output signal that is representative of the phase and amplitude change caused by the reflection of the signal at the probe exposed to the fluid. The detector may be a dual phase detector that provides two such output signals that are in phase quadrature. A phase shifter may be provided for selectively changing the phase of the reference signal to improve the sensitivity of at least one of the output signals for more accurate readings and/or for calibration purposes. The two outputs that are in quadrature with respect to each other may be simultaneously monitored to account for
Why do some patients not cash their prescriptions?
Jones, I; Britten, N
1998-01-01
BACKGROUND: A small number of studies have used different methodologies to measure primary non-compliance, but they have not established the reasons for patients not cashing their prescriptions. It has been suggested that the number of uncashed prescriptions is a measure of the quality of doctor-patient communication, but this hypothesis remains untested. AIM: To establish the feasibility of obtaining data on a sensitive subject from patients by interview and to seek patients' reasons for not cashing prescriptions using qualitative data. METHOD: Questionnaire administered to 1000 consecutive patients attending surgery, followed by interview with those patients who indicated that they had not cashed the index prescription. RESULTS: The response rate was 93.5%. Twenty-two patients were included in the study. There was wide variation in the number of uncashed prescriptions issued by each doctor (1-13). A total of nine out of 22 patients reported that their medication was cheaper over the counter and obtained it in this way; 13 out of 22 did not obtain their medication. Five patients indicated that cost was a factor in not obtaining their medication. Other factors included the doctor's permission not to cash the prescription, poor understanding of the illness, and the wish to maintain control. CONCLUSION: It is feasible to ask patients about aspects of their behaviour that may indicate, or cause, difficulties in the doctor-patient relationship. Prescribing behaviour varies widely between doctors and, although cost is a factor in determining whether a prescription will be cashed, other variables, such as the patient's desire to maintain control over the illness, may be more important. PMID:9604414
On methods of estimating cosmological bulk flows
NASA Astrophysics Data System (ADS)
Nusser, Adi
2016-01-01
We explore similarities and differences between several estimators of the cosmological bulk flow, B, from the observed radial peculiar velocities of galaxies. A distinction is made between two theoretical definitions of B as a dipole moment of the velocity field weighted by a radial window function. One definition involves the three-dimensional (3D) peculiar velocity, while the other is based on its radial component alone. Different methods attempt at inferring B for either of these definitions which coincide only for the case of a velocity field which is constant in space. We focus on the Wiener Filtering (WF) and the Constrained Minimum Variance (CMV) methodologies. Both methodologies require a prior expressed in terms of the radial velocity correlation function. Hoffman et al. compute B in Top-Hat windows from a WF realization of the 3D peculiar velocity field. Feldman et al. infer B directly from the observed velocities for the second definition of B. The WF methodology could easily be adapted to the second definition, in which case it will be equivalent to the CMV with the exception of the imposed constraint. For a prior with vanishing correlations or very noisy data, CMV reproduces the standard Maximum Likelihood estimation for B of the entire sample independent of the radial weighting function. Therefore, this estimator is likely more susceptible to observational biases that could be present in measurements of distant galaxies. Finally, two additional estimators are proposed.
Polynominal Interpolation Methods for Viscous Flow Calculations
NASA Technical Reports Server (NTRS)
Rubin, S. G.; Khosla, P. K.
1976-01-01
Higher-order collocation procedures resulting in tridiagonal matrix systems are derived from polynomial spline interpolation and by Hermitian (Taylor series) finite-difference discretization. The similarities and special features of these different developments are discussed. The governing systems apply for both uniform and variable meshes. Hybrid schemes resulting from two different polynomial approximations for the first and second derivatives lead to a nonuniform mesh extension of the so-called compact or Pad? difference technique (Hermite 4). A variety of fourth-order methods are described and the Hermitian approach is extended to sixth-order (Hermite 6). The appropriate spline boundary conditions are derived for all procedures. For central finite differences, this leads to a two-point, second-order accurate generalization of the commonly used three-point end-difference formula. Solutions with several spline and Hermite procedures are presented for the boundary layer equations, with and without mass transfer, and for the incompressible viscous flow in a driven cavity. Divergence and nondivergence equations are considered for the cavity. Among the fourth-order techniques, it is shown that spline 4 has the smallest truncation error. The spline 4 procedure generally requires one-quarter the number of mesh points in a given coordinate direction as a central finite-difference calculation of equal accuracy. The Hermite 6 procedure leads to remarkably accurate boundary layer solutions.
Climate change, cash transfers and health
Shaw, Caroline; Rasanathan, Kumanan; Yablonski, Jennifer; Kawachi, Ichiro; Hales, Simon
2015-01-01
Abstract The forecast consequences of climate change on human health are profound, especially in low- and middle-income countries and among the most disadvantaged populations. Innovative policy tools are needed to address the adverse health effects of climate change. Cash transfers are established policy tools for protecting population health before, during and after climate-related disasters. For example, the Ethiopian Productive Safety Net Programme provides cash transfers to reduce food insecurity resulting from droughts. We propose extending cash transfer interventions to more proactive measures to improve health in the context of climate change. We identify promising cash transfer schemes that could be used to prevent the adverse health consequences of climatic hazards. Cash transfers for using emission-free, active modes of transport – e.g. cash for cycling to work – could prevent future adverse health consequences by contributing to climate change mitigation and, at the same time, improving current population health. Another example is cash transfers provided to communities that decide to move to areas in which their lives and health are not threatened by climatic disasters. More research on such interventions is needed to ensure that they are effective, ethical, equitable and cost–effective. PMID:26478613
Climate change, cash transfers and health.
Pega, Frank; Shaw, Caroline; Rasanathan, Kumanan; Yablonski, Jennifer; Kawachi, Ichiro; Hales, Simon
2015-08-01
The forecast consequences of climate change on human health are profound, especially in low- and middle-income countries and among the most disadvantaged populations. Innovative policy tools are needed to address the adverse health effects of climate change. Cash transfers are established policy tools for protecting population health before, during and after climate-related disasters. For example, the Ethiopian Productive Safety Net Programme provides cash transfers to reduce food insecurity resulting from droughts. We propose extending cash transfer interventions to more proactive measures to improve health in the context of climate change. We identify promising cash transfer schemes that could be used to prevent the adverse health consequences of climatic hazards. Cash transfers for using emission-free, active modes of transport - e.g. cash for cycling to work - could prevent future adverse health consequences by contributing to climate change mitigation and, at the same time, improving current population health. Another example is cash transfers provided to communities that decide to move to areas in which their lives and health are not threatened by climatic disasters. More research on such interventions is needed to ensure that they are effective, ethical, equitable and cost-effective. PMID:26478613
Turbomachinery flow calculation on unstructured grids using finite element method
NASA Astrophysics Data System (ADS)
Koschel, W.; Vornberger, A.
An explicit finite-element scheme based on a two-step Taylor-Galerkin algorithm allows the solution of the Euler and Navier-Stokes equations on unstructured grids. Mesh generation methods for unstructured grids are described which lead to efficient flow calculations. Turbulent flow is calculated by using an algebraic turbulence model. To test the numerical accuracy, a laminar and turbulent flow over a flat plate and the supersonic flow in a corner has been calculated. For validation the method is applied to the simulation of the inviscid flow through a transonic turbine cascade and the viscous flow through a subsonic turbine cascade.
Application of a parallel DSMC method to hypersonic rarefied flows
Wilmoth, R.G. )
1991-01-01
This paper describes a method for doing direct simulation Monte Carlo (DSMC) calculations using parallel processing and presents some results of applying the method to several hypersonic, rarefied flow problems. The performance and efficiency of the parallel method are discussed. The applications described are the flow in a channel and the flow about a flat plate at incidence. The results show significant advantages of parallel processing over conventional scalar processing and demonstrate the scalability of the method to large problems. 8 refs.
Force-coupling method for flows with ellipsoidal particles
NASA Astrophysics Data System (ADS)
Liu, D.; Keaveny, E. E.; Maxey, M. R.; Karniadakis, G. E.
2009-06-01
The force-coupling method, previously developed for spherical particles suspended in a liquid flow, is extended to ellipsoidal particles. In the limit of Stokes flow, there is an exact correspondence with known analytical results for isolated particles. More generally, the method is shown to provide good approximate results for the particle motion and the flow field both in viscous Stokes flow and at finite Reynolds number. This is demonstrated through comparison between fully resolved direct numerical simulations and results from the numerical implementation of the force-coupling method with a spectral/hp element scheme. The motion of settling ellipsoidal particles and neutrally buoyant particles in a Poiseuille flow are discussed.
Field methods for measuring concentrated flow erosion
NASA Astrophysics Data System (ADS)
Castillo, C.; Pérez, R.; James, M. R.; Quinton, J. N.; Taguas, E. V.; Gómez, J. A.
2012-04-01
techniques (3D) for measuring erosion from concentrated flow (pole, laser profilemeter, photo-reconstruction and terrestrial LiDAR) The comparison between two- and three-dimensional methods has showed the superiority of the 3D techniques for obtaining accurate cross sectional data. The results from commonly-used 2D methods can be subject to systematic errors in areal cross section that exceed magnitudes of 10 % on average. In particular, the pole simplified method has showed a clear tendency to understimate areas. Laser profilemeter results show that further research on calibrating optical devices for a variety of soil conditions must be carried out to improve its performance. For volume estimations, photo-reconstruction results provided an excellent approximation to terrestrial laser data and demonstrate that this new remote sensing technique has a promising application field in soil erosion studies. 2D approaches involved important errors even over short measurement distances. However, as well as accuracy, the cost and time requirements of a technique must be considered.
PDF methods for turbulent reactive flows
NASA Technical Reports Server (NTRS)
Hsu, Andrew T.
1995-01-01
Viewgraphs are presented on computation of turbulent combustion, governing equations, closure problem, PDF modeling of turbulent reactive flows, validation cases, current projects, and collaboration with industry and technology transfer.
47 CFR 36.182 - Cash working capital.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 47 Telecommunication 2 2011-10-01 2011-10-01 false Cash working capital. 36.182 Section 36.182 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES JURISDICTIONAL SEPARATIONS... Cash Working Capital § 36.182 Cash working capital. (a) The amount for cash working capital, if...
47 CFR 36.182 - Cash working capital.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 47 Telecommunication 2 2010-10-01 2010-10-01 false Cash working capital. 36.182 Section 36.182 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES JURISDICTIONAL SEPARATIONS... Cash Working Capital § 36.182 Cash working capital. (a) The amount for cash working capital, if...
25 CFR 141.19 - Check cashing.
Code of Federal Regulations, 2010 CFR
2010-04-01
... may give a fully negotiable check in addition to U.S. currency when cashing a draft, check or money... or any other obligation the customer owes to the business, but in no event may the owner or...
Flow patterns measurements with PIV laser method
NASA Astrophysics Data System (ADS)
Podlinski, Janusz; Kocik, Marek; Dors, Miroslaw; Metel, Emilia; Mizeraczyk, Jerzy
2007-03-01
In this paper a Particle Image Velocimetry (PIV) measurement technique and it's application for the flow patterns measurements in our experiments is presented. Present PIV system consist of double Nd:YAG laser with pulse energy of 50 mJ, optics for transmission and formation a laser beam, two CCD cameras (Kodak MegaPlus ES-1.0 and FlowSense M2), Dantec processor PIV 1100 and PC computer with FlowManager software. The maximum measured area is 0.5 m2 and flow velocity in the range of 0-300 m/s. So far, the PIV measurements were carried out in hydrodynamic and transonic ducts, corona discharge reactors, electrostatic precipitator models and a microwave torch discharge reactor in The Szewalski Institute of Fluid Flow Machinery, Polish Academy of Sciences in Gdansk. The PIV system was used also for the measurements of the velocity fields round the hull of the ship model in The Ship Design and Research Centre in Gdansk.
Moving and adaptive grid methods for compressible flows
NASA Technical Reports Server (NTRS)
Trepanier, Jean-Yves; Camarero, Ricardo
1995-01-01
This paper describes adaptive grid methods developed specifically for compressible flow computations. The basic flow solver is a finite-volume implementation of Roe's flux difference splitting scheme or arbitrarily moving unstructured triangular meshes. The grid adaptation is performed according to geometric and flow requirements. Some results are included to illustrate the potential of the methodology.
Code of Federal Regulations, 2013 CFR
2013-04-01
... cage, vault, kiosk, cash and cash equivalents? 543.18 Section 543.18 Indians NATIONAL INDIAN GAMING... § 543.18 What are the minimum internal control standards for the cage, vault, kiosk, cash and cash equivalents? (a) Supervision. Supervision must be provided as needed for cage, vault, kiosk, and...
Code of Federal Regulations, 2014 CFR
2014-04-01
... cage, vault, kiosk, cash and cash equivalents? 543.18 Section 543.18 Indians NATIONAL INDIAN GAMING... § 543.18 What are the minimum internal control standards for the cage, vault, kiosk, cash and cash equivalents? (a) Supervision. Supervision must be provided as needed for cage, vault, kiosk, and...
Method and apparatus for monitoring two-phase flow. [PWR
Sheppard, J.D.; Tong, L.S.
1975-12-19
A method and apparatus for monitoring two-phase flow is provided that is particularly related to the monitoring of transient two-phase (liquid-vapor) flow rates such as may occur during a pressurized water reactor core blow-down. The present invention essentially comprises the use of flanged wire screens or similar devices, such as perforated plates, to produce certain desirable effects in the flow regime for monitoring purposes. One desirable effect is a measurable and reproducible pressure drop across the screen. The pressure drop can be characterized for various known flow rates and then used to monitor nonhomogeneous flow regimes. Another useful effect of the use of screens or plates in nonhomogeneous flow is that such apparatus tends to create a uniformly dispersed flow regime in the immediate downstream vicinity. This is a desirable effect because it usually increases the accuracy of flow rate measurements determined by conventional methods.
Noninvasive method of estimating human newborn regional cerebral blood flow
Younkin, D.P.; Reivich, M.; Jaggi, J.; Obrist, W.; Delivoria-Papadopoulos, M.
1982-12-01
A noninvasive method of estimating regional cerebral blood flow (rCBF) in premature and full-term babies has been developed. Based on a modification of the /sup 133/Xe inhalation rCBF technique, this method uses eight extracranial NaI scintillation detectors and an i.v. bolus injection of /sup 133/Xe (approximately 0.5 mCi/kg). Arterial xenon concentration was estimated with an external chest detector. Cerebral blood flow was measured in 15 healthy, neurologically normal premature infants. Using Obrist's method of two-compartment analysis, normal values were calculated for flow in both compartments, relative weight and fractional flow in the first compartment (gray matter), initial slope of gray matter blood flow, mean cerebral blood flow, and initial slope index of mean cerebral blood flow. The application of this technique to newborns, its relative advantages, and its potential uses are discussed.
A method of determining combustion gas flow
NASA Technical Reports Server (NTRS)
Bon Tempi, P. J.
1968-01-01
Zirconium oxide coating enables the determination of hot gas flow patterns on liquid rocket injector face and baffle surfaces to indicate modifications that will increase performance and improve combustion stability. The coating withstands combustion temperatures and due to the coarse surface and coloring of the coating, shows the hot gas patterns.
APPROXIMATE MULTIPHASE FLOW MODELING BY CHARACTERISTIC METHODS
The flow of petroleum hydrocarbons, organic solvents and other liquids that are immiscible with water presents the nation with some of the most difficult subsurface remediation problems. One aspect of contaminant transport associated releases of such liquids is the transport as a...
Embedded function methods for compressible high speed turbulent flow
NASA Technical Reports Server (NTRS)
Walker, J. D. A.
1989-01-01
Fundamental issues relating to compressible turbulent flow are addressed. The focus has been on developing methods and testing concepts for attached flows rather than trying to force a conventional law of the wall into a zone of backflow. Although the dynamics of the near-wall flow in an attached turbulent boundary layer are relatively well documented, the dynamical features of a zone of reversed turbulent flow are not, nor are they well understood. Incompressibility introduces effects and issues that have been dealt with only marginally in the literature, therefore, the present work has been focussed on attached high-speed flows. The wall function method has been extended up through the supersonic to hypersonic speeds. Algorithms have been successfully introduced into the code that calculates the flow all the way to the wall, and testing is being carried out for progressively more complex flow situations.
Methods for improved resolution of flow electrophoresis cells
NASA Technical Reports Server (NTRS)
Mccreight, L. R.; Fogal, G. L.
1974-01-01
First method involves remote adjusting of zeta potential. Second approach sandwiches two conducting metal plates between opposite cell walls and thin insulating layer. Third method forces buffer to flow in direction opposite particle streams.
Evaluation of flow direction methods against field observations of overland flow dispersion
NASA Astrophysics Data System (ADS)
Orlandini, Stefano; Moretti, Giovanni; Corticelli, Mauro A.; Santangelo, Paolo E.; Capra, Alessandro; Rivola, Riccardo; Albertson, John D.
2012-10-01
The D8, D8-LTD, D∞-LTD, D∞, MD∞, and MD8 flow direction methods are evaluated against field observations of overland flow dispersion obtained from novel experimental methods. Thin flows of cold water were released at selected points on a warmer slope and individual overland flow patterns originating from each of these points were observed using a terrestrial laser scanner and a thermal imaging camera. Land microtopography was determined by using laser returns from the dry land surface, whereas overland flow patterns were determined by using either laser returns or infrared emissions from the wetted portions of the land surface. Planar overland flow dispersion is found to play an important role in the region lying immediately downslope of the point source, but attenuates rapidly as flow propagates downslope. In contrast, existing dispersive flow direction methods are found to provide a continued dispersion with distance downslope. Predicted propagation patterns, for all methods considered here, depend critically on the size h of grid cells involved. All methods are found to be poorly sensitive in extremely fine grids (h ≤ 2 cm), and to be poorly specific in coarse grids (h = 2 m). Satisfactory results are, however, obtained in grids having resolutions h that approach the average flow width (50 cm), with the best performances displayed by the MD8 method in the finest grids (5 ≤ h ≤ 20 cm), and by the MD∞, D∞, and D∞-LTD methods in the coarsest grids (20 cm < h ≤ 1 m).
Ultrasonic fluid flow measurement method and apparatus
Kronberg, J.W.
1993-10-12
An apparatus for measuring the flow of a fluid in a pipe using ultrasonic waves. The apparatus comprises an ultrasonic generator, a lens for focusing the sound energy produced by the generator, and means for directing the focused energy into the side of the pipe through an opening and in a direction close to parallel to the long axis of the pipe. A cone carries the sound energy to the lens from the generator. Depending on the choice of materials, there may be a quarter-wave, acoustic impedance matching section between the generator and the cone to reduce the reflections of energy at the cone boundary. The lens material has an acoustic impedance similar to that of the cone material but a different sonic velocity so that the lens can converge the sound waves in the fluid. A transition section between the lens and the fluid helps to couple the energy to the fluid and assures it is directed as close to parallel to the fluid flow direction as possible. 3 figures.
Ultrasonic fluid flow measurement method and apparatus
Kronberg, James W.
1993-01-01
An apparatus for measuring the flow of a fluid in a pipe using ultrasonic waves. The apparatus comprises an ultrasonic generator, a lens for focusing the sound energy produced by the generator, and means for directing the focused energy into the side of the pipe through an opening and in a direction close to parallel to the long axis of the pipe. A cone carries the sound energy to the lens from the generator. Depending on the choice of materials, there may be a quarter-wave, acoustic impedance matching section between the generator and the cone to reduce the reflections of energy at the cone boundary. The lens material has an acoustic impedance similar to that of the cone material but a different sonic velocity so that the lens can converge the sound waves in the fluid. A transition section between the lens and the fluid helps to couple the energy to the fluid and assures it is directed as close to parallel to the fluid flow direction as possible.
A New Method for Stabilizing Non-Newtonian Flows
NASA Astrophysics Data System (ADS)
Symeonidis, V.; Ma, X.; Karniadakis, G. E.
2002-11-01
In this work we will demonstrate a robust and adjustable filtering method for viscoelastic flows, applied mainly on the FENE-P model, called the spectrally varying viscosity (SVV) method. We will present results demonstrating spectral accuracy and resolution studies on the benchmark two-dimensional flow around a cylinder in a symmetric channel, and in the analogous three-dimensional flow around a sphere in a tube. Unsteady results are included in three-dimensions, and we examine the flow around an ellipsoid in transitional and turbulent states. We demonstrate a set of stable parameters for the SVV filtering and compare these results with previous published works on the same benchmark problems.
Gravimetric method for the dynamic measurement of urine flow.
Steele, J E; Skarlatos, S; Brand, P H; Metting, P J; Britton, S L
1993-10-01
The rate of urine formation is a primary index of renal function, but no techniques are currently available to accurately measure low rates of urine flow on a continuous basis, such as are normally found in rats. We developed a gravimetric method for the dynamic measurement of urine flow in anesthetized rats. Catheters were inserted directly into the ureters close to the renal pelves, and a siphon was created to collect all of the urine formed as rapidly as it was produced. Urine flow was determined by measuring the weight of the urine using a direct-reading analytical balance interfaced to a computer. Basal urine flow was measured at 2-sec intervals for 30 to 60 min. The dynamic response of urine flow to a rapid decrease in arterial pressure produced by a bolus intravenous injection of acetylcholine (0.5 micrograms) was also measured. Intrinsic drift, evaporative losses, and the responsiveness of the system to several fixed pump flows in the low physiologic range were evaluated in vitro. The gravimetric method described was able to continuously measure basal urine flows that averaged 37.3 +/- 12.4 microliters/min. Error due to drift and evaporation was negligible, totaling less than 1% of the measured urine flow. Acetylcholine-induced declines in arterial pressure were followed within 8 sec by a decline in urine flow. These data demonstrate that this new gravimetric method provides a simple, inexpensive, dynamic measurement of urine flow in the microliter/min range. PMID:8372099
An airfoil design method for viscous flows
NASA Technical Reports Server (NTRS)
Malone, J. B.; Narramore, J. C.; Sankar, L. N.
1990-01-01
An airfoil design procedure is described that has been incorporated into an existing two-dimensional Navier-Stokes airfoil analysis method. The resulting design method, an iterative procedure based on a residual-correction algorithm, permits the automated design of airfoil sections with prescribed surface pressure distributions. This paper describes the inverse design method and the technique used to specify target pressure distributions. An example airfoil design problem is described to demonstrate application of the inverse design procedure. It shows that this inverse design method develops useful airfoil configurations with a reasonable expenditure of computer resources.
Fourier time spectral method for subsonic and transonic flows
NASA Astrophysics Data System (ADS)
Zhan, Lei; Liu, Feng; Papamoschou, Dimitri
2016-06-01
The time accuracy of the exponentially accurate Fourier time spectral method (TSM) is examined and compared with a conventional 2nd-order backward difference formula (BDF) method for periodic unsteady flows. In particular, detailed error analysis based on numerical computations is performed on the accuracy of resolving the local pressure coefficient and global integrated force coefficients for smooth subsonic and non-smooth transonic flows with moving shock waves on a pitching airfoil. For smooth subsonic flows, the Fourier TSM method offers a significant accuracy advantage over the BDF method for the prediction of both the local pressure coefficient and integrated force coefficients. For transonic flows where the motion of the discontinuous shock wave contributes significant higher-order harmonic contents to the local pressure fluctuations, a sufficient number of modes must be included before the Fourier TSM provides an advantage over the BDF method. The Fourier TSM, however, still offers better accuracy than the BDF method for integrated force coefficients even for transonic flows. A problem of non-symmetric solutions for symmetric periodic flows due to the use of odd numbers of intervals is uncovered and analyzed. A frequency-searching method is proposed for problems where the frequency is not known a priori. The method is tested on the vortex shedding problem of the flow over a circular cylinder.
Fourier time spectral method for subsonic and transonic flows
NASA Astrophysics Data System (ADS)
Zhan, Lei; Liu, Feng; Papamoschou, Dimitri
2016-01-01
The time accuracy of the exponentially accurate Fourier time spectral method (TSM) is examined and compared with a conventional 2nd-order backward difference formula (BDF) method for periodic unsteady flows. In particular, detailed error analysis based on numerical computations is performed on the accuracy of resolving the local pressure coefficient and global integrated force coefficients for smooth subsonic and non-smooth transonic flows with moving shock waves on a pitching airfoil. For smooth subsonic flows, the Fourier TSM method offers a significant accuracy advantage over the BDF method for the prediction of both the local pressure coefficient and integrated force coefficients. For transonic flows where the motion of the discontinuous shock wave contributes significant higher-order harmonic contents to the local pressure fluctuations, a sufficient number of modes must be included before the Fourier TSM provides an advantage over the BDF method. The Fourier TSM, however, still offers better accuracy than the BDF method for integrated force coefficients even for transonic flows. A problem of non-symmetric solutions for symmetric periodic flows due to the use of odd numbers of intervals is uncovered and analyzed. A frequency-searching method is proposed for problems where the frequency is not known a priori. The method is tested on the vortex shedding problem of the flow over a circular cylinder.
Method and apparatus for coal analysis and flow measurement
Rollwitz, W.L.; King, J.D.
1985-07-23
A flow meter apparatus and method for measuring the flow, composition and heat content of coal is set forth. In the preferred and illustrated embodiment, the free or unpaired electron population of flowing coal is measured by electron magnetic resonance (EMR); the hydrogen nucleii population is measured by nuclear magnetic resonance (NMR). By calibration utilizing a standard specimen for a given type of coal, a profile for various types of coal can be obtained wherein measurement data is converted into an indication of the heat content typically measured in BTU per pound. This enables provision of a volumetric flow meter, a flow meter indicating flow in calorie content. This device enables integration to provide total heat content flow. Other variables describing the coal can be obtained.
Vortex method for blood flow through heart valves
McCracken, M.F.; Peskin, C.S.
1980-04-01
A combination vortex-grid method for solving the two-dimensional, incompressible Navier--Stokes equations in regions with complicated internal, elastic boundaries is presented. The authors believe the method to be applicable to the case of at least moderately high Reynolds number flow. The method is applied to the study of blood flow through the mammalian mitral valve. Previous work of Peskin is extended and the conjecture that the behavior of mammalian heart valves is independent of Reynolds number is supported.
Advanced surface paneling method for subsonic and supersonic flow
NASA Technical Reports Server (NTRS)
Erickson, L. L.; Johnson, F. T.; Ehlers, F. E.
1976-01-01
Numerical results illustrating the capabilities of an advanced aerodynamic surface paneling method are presented. The method is applicable to both subsonic and supersonic flow, as represented by linearized potential flow theory. The method is based on linearly varying sources and quadratically varying doublets which are distributed over flat or curved panels. These panels are applied to the true surface geometry of arbitrarily shaped three dimensional aerodynamic configurations.
Spectral multigrid methods with applications to transonic potential flow
NASA Technical Reports Server (NTRS)
Streett, C. L.; Zang, T. A.; Hussaini, M. Y.
1983-01-01
Spectral multigrid methods are demonstrated to be a competitive technique for solving the transonic potential flow equation. The spectral discretization, the relaxation scheme, and the multigrid techniques are described in detail. Significant departures from current approaches are first illustrated on several linear problems. The principal applications and examples, however, are for compressible potential flow. These examples include the relatively challenging case of supercritical flow over a lifting airfoil.
Spectral multigrid methods with applications to transonic potential flow
NASA Technical Reports Server (NTRS)
Streett, C. L.; Zang, T. A.; Hussaini, M. Y.
1985-01-01
Spectral multigrid methods are demonstrated to be a competitive technique for solving the transonic potential flow equation. The spectral discretization, the relaxation scheme, and the multigrid techniques are described in detail. Significant departures from current approaches are first illustrated on several linear problems. The principal applications and examples, however, are for compressible potential flow. These examples include the relatively challenging case of supercritical flow over a lifting airfoil.
Review of Upscaling Methods for Describing Unsaturated Flow
Wood, Brian D.
2000-09-26
Representing samll-scale features can be a challenge when one wants to model unsaturated flow in large domains. In this report, the various upscaling techniques are reviewed. The following upscaling methods have been identified from the literature: stochastic methods, renormalization methods, volume averaging and homogenization methods. In addition, a final technique, full resolution numerical modeling, is also discussed.
Computation of Transonic Flows Using Potential Methods
NASA Technical Reports Server (NTRS)
Hoist, Terry L.; Kwak, Dochan (Technical Monitor)
1997-01-01
The proposed paper will describe the state of the art associated with numerical solution of the full or exact velocity potential equation for solving transonic, external-aerodynamic flows. The presentation will begin with a review of the literature emphasizing research activities of the past decade. Next, the various forms of the full or exact velocity potential equation, the equation's corresponding mathematical characteristics, and the derivation assumptions will be presented and described in detail. Impact of the derivation assumptions on simulation accuracy, especially with respect to shock wave capture, will be presented and discussed relative to the more complete Euler or Navier-Stokes formulations. The technical presentation will continue with a description of recently developed full potential numerical approach characteristics. This description will include governing equation nondimensionalization, physical-to-computational-domain mapping procedures, a limited description of grid generation requirements, the spatial discretization scheme, numerical implementation of boundary conditions, and the iteration scheme. The next portion of the presentation will present and discuss numerical results for several two- and three-dimensional aerodynamic applications. Included in the results section will be a discussion and demonstration of a typical grid refinement analysis for determining spatial convergence of the numerical solution and level of solution accuracy. Computer timings for a variety of full potential applications will be compared and contrasted with similar results for the Euler equation formulation. Finally. the presentation will end with concluding remarks and recommendations for future work.
An artificial energy method for calculating flows with shocks
NASA Technical Reports Server (NTRS)
Rose, M. E.
1980-01-01
The artificial-viscosity method, first proposed by von Neumann and Richtmyer, introduces an artificial viscous pressure term in regions of compression such that an increase in entropy occurs in shock transition zones. The paper describes how dissipative flows can be induced by reducing the total energy available for adiabatic processes in shock zones. A class of inviscid fluid flows, called semiflows, is described in which the flows exhibit thermodynamic differences. Induced dissipative flows modify the pressure in regions of compression in a manner analogous to the artificial-viscosity method and for a gas, the effect is equivalent to suitably modifying the gas constant in the equation of state. By employing MacCormack's method and the usual non-adiabatic equations, numerical solutions of a Riemann problem are compared with the modified artificial energy method, showing that the dissipation effect predicted by the analytical formulation is reflected in the numerical method as well.
A Reconstruction Method of Blood Flow Velocity in Left Ventricle Using Color Flow Ultrasound
Jang, Jaeseong; Ahn, Chi Young; Jeon, Kiwan; Heo, Jung; Lee, DongHak; Choi, Jung-il
2015-01-01
Vortex flow imaging is a relatively new medical imaging method for the dynamic visualization of intracardiac blood flow, a potentially useful index of cardiac dysfunction. A reconstruction method is proposed here to quantify the distribution of blood flow velocity fields inside the left ventricle from color flow images compiled from ultrasound measurements. In this paper, a 2D incompressible Navier-Stokes equation with a mass source term is proposed to utilize the measurable color flow ultrasound data in a plane along with the moving boundary condition. The proposed model reflects out-of-plane blood flows on the imaging plane through the mass source term. The boundary conditions to solve the system of equations are derived from the dimensions of the ventricle extracted from 2D echocardiography data. The performance of the proposed method is evaluated numerically using synthetic flow data acquired from simulating left ventricle flows. The numerical simulations show the feasibility and potential usefulness of the proposed method of reconstructing the intracardiac flow fields. Of particular note is the finding that the mass source term in the proposed model improves the reconstruction performance. PMID:26078773
Chaotic maps, Hamiltonian flows, and Holographic methods.
Curtright, T. L.; Zachos, C. K.; High Energy Physics; Univ. of Miami
2010-01-01
Holographic functional methods are introduced as probes of discrete time-stepped maps that lead to chaotic behavior. The methods provide continuous time interpolation between the time steps, thereby revealing the maps to be quasi-Hamiltonian systems underlain by novel potentials that govern the motion of a perceived point particle. Between turning points, the particle is strictly driven by Hamiltonian dynamics, but at each encounter with a turning point the potential changes abruptly, loosely analogous to the switchbacks on a mountain road. A sequence of successively deepening switchback potentials explains, in physical terms, the frequency cascade and trajectory folding that occur on the particular route to chaos revealed by the logistic map.
Vortical Flow Prediction Using an Adaptive Unstructured Grid Method
NASA Technical Reports Server (NTRS)
Pirzadeh, Shahyar Z.
2003-01-01
A computational fluid dynamics (CFD) method has been employed to compute vortical flows around slender wing/body configurations. The emphasis of the paper is on the effectiveness of an adaptive grid procedure in "capturing" concentrated vortices generated at sharp edges or flow separation lines of lifting surfaces flying at high angles of attack. The method is based on a tetrahedral unstructured grid technology developed at the NASA Langley Research Center. Two steady-state, subsonic, inviscid and Navier-Stokes flow test cases are presented to demonstrate the applicability of the method for solving practical vortical flow problems. The first test case concerns vortex flow over a simple 65 delta wing with different values of leading-edge radius. Although the geometry is quite simple, it poses a challenging problem for computing vortices originating from blunt leading edges. The second case is that of a more complex fighter configuration. The superiority of the adapted solutions in capturing the vortex flow structure over the conventional unadapted results is demonstrated by comparisons with the wind-tunnel experimental data. The study shows that numerical prediction of vortical flows is highly sensitive to the local grid resolution and that the implementation of grid adaptation is essential when applying CFD methods to such complicated flow problems.
Vortical Flow Prediction Using an Adaptive Unstructured Grid Method
NASA Technical Reports Server (NTRS)
Pirzadeh, Shahyar Z.
2001-01-01
A computational fluid dynamics (CFD) method has been employed to compute vortical flows around slender wing/body configurations. The emphasis of the paper is on the effectiveness of an adaptive grid procedure in "capturing" concentrated vortices generated at sharp edges or flow separation lines of lifting surfaces flying at high angles of attack. The method is based on a tetrahedral unstructured grid technology developed at the NASA Langley Research Center. Two steady-state, subsonic, inviscid and Navier-Stokes flow test cases are presented to demonstrate the applicability of the method for solving practical vortical flow problems. The first test case concerns vortex flow over a simple 65deg delta wing with different values of leading-edge bluntness, and the second case is that of a more complex fighter configuration. The superiority of the adapted solutions in capturing the vortex flow structure over the conventional unadapted results is demonstrated by comparisons with the windtunnel experimental data. The study shows that numerical prediction of vortical flows is highly sensitive to the local grid resolution and that the implementation of grid adaptation is essential when applying CFD methods to such complicated flow problems.
Construction of School Timetables by Flow Methods.
ERIC Educational Resources Information Center
de Werra, D.
In this paper, a heuristic algorithm for constructing school timetables is described. The algorithm is based on an exact method that applies to a family of particular timetable problems. The procedure has been used to construct timetables for Swiss schools having about 50 classes, 80 teachers, and 35 weekly periods. Less than five percent of…
PDF methods for combustion in high-speed turbulent flows
NASA Technical Reports Server (NTRS)
Pope, Stephen B.
1995-01-01
This report describes the research performed during the second year of this three-year project. The ultimate objective of the project is extend the applicability of probability density function (pdf) methods from incompressible to compressible turbulent reactive flows. As described in subsequent sections, progress has been made on: (1) formulation and modelling of pdf equations for compressible turbulence, in both homogeneous and inhomogeneous inert flows; and (2) implementation of the compressible model in various flow configurations, namely decaying isotropic turbulence, homogeneous shear flow and plane mixing layer.
Inconsistency of Species Tree Methods under Gene Flow.
Solís-Lemus, Claudia; Yang, Mengyao; Ané, Cécile
2016-09-01
Coalescent-based methods are now broadly used to infer evolutionary relationships between groups of organisms under the assumption that incomplete lineage sorting (ILS) is the only source of gene tree discordance. Many of these methods are known to consistently estimate the species tree when all their assumptions are met. Nonetheless, little work has been done to test the robustness of such methods to violations of their assumptions. Here, we study the performance of two of the most efficient coalescent-based methods, ASTRAL and NJst, in the presence of gene flow. Gene flow violates the assumption that ILS is the sole source of gene tree conflict. We find anomalous gene trees on three-taxon rooted trees and on four-taxon unrooted trees. These anomalous trees do not exist under ILS only, but appear because of gene flow. Our simulations show that species tree methods (and concatenation) may reconstruct the wrong evolutionary history, even from a very large number of well-reconstructed gene trees. In other words, species tree methods can be inconsistent under gene flow. Our results underline the need for methods like PhyloNet, to account simultaneously for ILS and gene flow in a unified framework. Although much slower, PhyloNet had better accuracy and remained consistent at high levels of gene flow. PMID:27151419
The art and science of flow control - case studies using flow visualization methods
NASA Astrophysics Data System (ADS)
Alvi, F. S.; Cattafesta, L. N., III
2010-04-01
Active flow control (AFC) has been the focus of significant research in the last decade. This is mainly due to the potentially substantial benefits it affords. AFC applications range from the subsonic to the supersonic (and beyond) regime for both internal and external flows. These applications are wide and varied, such as controlling flow transition and separation over various external components of the aircraft to active management of separation and flow distortion in engine components and over turbine and compressor blades. High-speed AFC applications include control of flow oscillations in cavity flows, supersonic jet screech, impinging jets, and jet-noise control. In this paper we review some of our recent applications of AFC through a number of case studies that illustrate the typical benefits as well as limitations of present AFC methods. The case studies include subsonic and supersonic canonical flowfields such as separation control over airfoils, control of supersonic cavity flows and impinging jets. In addition, properties of zero-net mass-flux (ZNMF) actuators are also discussed as they represent one of the most widely studied actuators used for AFC. In keeping with the theme of this special issue, the flowfield properties and their response to actuation are examined through the use of various qualitative and quantitative flow visualization methods, such as smoke, shadowgraph, schlieren, planar-laser scattering, and Particle image velocimetry (PIV). The results presented here clearly illustrate the merits of using flow visualization to gain significant insight into the flow and its response to AFC.
Evaluation of flow direction methods against field observations of overland flow dispersion
NASA Astrophysics Data System (ADS)
Orlandini, S.; Moretti, G.; Corticelli, M. A.; Santangelo, P. E.; Capra, A.; Rivola, R.; Albertson, J. D.
2012-12-01
Despite the broad effort made in grid-based distributed catchment modeling to account for planar overland flow dispersion, actual dispersion experienced by overland flow along a natural slope has not been measured so far, and the ability of terrain analysis methods to reproduce this dispersion has not been evaluated. In the present study, the D8, D8-LTD, D∞ -LTD, D∞ , MD∞ , and MD8 flow direction methods are evaluated against field observations of overland flow dispersion obtained from novel experimental methods. Thin flows of cold (2--10oC) water were released at selected points on a warmer (15--30oC) slope and individual overland flow patterns originating from each of these points were observed using a terrestrial laser scanner and a thermal imaging camera. Prior to each experimental water release, a ScanStation C10 terrestrial laser scanner by Leica Geosystems was used to acquire a point cloud having average density of 25~points/cm2. This point cloud was used to generate alternative grid-based digital elevation models having resolution h ranging from 1~cm to 2~m. During the experiments, an Avio Advanced Thermo TVS-500EX camera by Nippon Avionics was used to monitor land surface temperature with resolution better than 0.05oC. The overland flow patterns were also found to be discernible in terrestrial laser scanner reflectance signal acquired immediately following the flow experiments. Overland flow patterns were determined by considering contrasted temperature and reflectance of the dry and wetted land surface portions. Predicted propagation patterns and observed flow patterns were compared by considering the fractions of flow released at the point source that propagates through the grid cells. Predictions of these quantities were directly provided by flow direction methods and by related flow accumulation algorithms. Suitable data for the comparison were derived from observed overland flow patterns by assuming a uniform distribution of flow along each
Developments in flow visualization methods for flight research
NASA Technical Reports Server (NTRS)
Holmes, Bruce J.; Obara, Clifford J.; Manuel, Gregory S.; Lee, Cynthia C.
1990-01-01
With the introduction of modern airplanes utilizing laminar flow, flow visualization has become an important diagnostic tool in determining aerodynamic characteristics such as surface flow direction and boundary-layer state. A refinement of the sublimating chemical technique has been developed to define both the boundary-layer transition location and the transition mode. In response to the need for flow visualization at subsonic and transonic speeds and altitudes above 20,000 feet, the liquid crystal technique has been developed. A third flow visualization technique that has been used is infrared imaging, which offers non-intrusive testing over a wide range of test conditions. A review of these flow visualization methods and recent flight results is presented for a variety of modern aircraft and flight conditions.
Pressure algorithm for elliptic flow calculations with the PDF method
NASA Technical Reports Server (NTRS)
Anand, M. S.; Pope, S. B.; Mongia, H. C.
1991-01-01
An algorithm to determine the mean pressure field for elliptic flow calculations with the probability density function (PDF) method is developed and applied. The PDF method is a most promising approach for the computation of turbulent reacting flows. Previous computations of elliptic flows with the method were in conjunction with conventional finite volume based calculations that provided the mean pressure field. The algorithm developed and described here permits the mean pressure field to be determined within the PDF calculations. The PDF method incorporating the pressure algorithm is applied to the flow past a backward-facing step. The results are in good agreement with data for the reattachment length, mean velocities, and turbulence quantities including triple correlations.
DEMONSTRATION BULLETIN: COLLOID POLISHING FILTER METHOD - FILTER FLOW TECHNOLOGY, INC.
The Filter Flow Technology, Inc. (FFT) Colloid Polishing Filter Method (CPFM) was tested as a transportable, trailer mounted, system that uses sorption and chemical complexing phenomena to remove heavy metals and nontritium radionuclides from water. Contaminated waters can be pro...
Godunov Method for Calculating Multicomponent Heterogeneous Medium Flows
NASA Astrophysics Data System (ADS)
Surov, V. S.
2014-03-01
The modified Godunov method intended for integrating the nondivergent systems that describe a multivelocity heterogeneous mixture flow is presented. The linearized Riemann solver has been used in solving the Riemann problems.
Packet flow monitoring tool and method
Thiede, David R [Richland, WA
2009-07-14
A system and method for converting packet streams into session summaries. Session summaries are a group of packets each having a common source and destination internet protocol (IP) address, and, if present in the packets, common ports. The system first captures packets from a transport layer of a network of computer systems, then decodes the packets captured to determine the destination IP address and the source IP address. The system then identifies packets having common destination IP addresses and source IP addresses, then writes the decoded packets to an allocated memory structure as session summaries in a queue.
Panel-Method Computer Code For Potential Flow
NASA Technical Reports Server (NTRS)
Ashby, Dale L.; Dudley, Michael R.; Iguchi, Steven K.
1992-01-01
Low-order panel method used to reduce computation time. Panel code PMARC (Panel Method Ames Research Center) numerically simulates flow field around or through complex three-dimensional bodies such as complete aircraft models or wind tunnel. Based on potential-flow theory. Facilitates addition of new features to code and tailoring of code to specific problems and computer-hardware constraints. Written in standard FORTRAN 77.
38 CFR 8.11 - Cash value and policy loan.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 38 Pensions, Bonuses, and Veterans' Relief 1 2014-07-01 2014-07-01 false Cash value and policy loan. 8.11 Section 8.11 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS NATIONAL SERVICE LIFE INSURANCE Cash Value and Policy Loan § 8.11 Cash value and policy loan. (a) Provisions for cash value, paid-up insurance, and...
Estimation of instantaneous peak flow from maximum daily flow-a comparison of methods
NASA Astrophysics Data System (ADS)
Ding, Jie; Haberlandt, Uwe
2013-04-01
Estimation of flood frequency based on instantaneous peak flow (IPF) is important for the design of hydraulic structures. However, observed flow data with high temporal resolution are scarce, especially regarding the limited length of the available flow time series. Here, three different methods are developed and compared to estimate the IPF based on maximum daily flow (MDF), which is available usually at more gauges and for longer time periods. In the first approach, simple linear regressions with non-intercept of probability weighted moments (PWM) or quantile values between IPF and MDF data are employed. Secondly, stepwise multiple linear regressions is used to generate regression equations describing the relationship between easily obtained catchment attributes and MDF predictors and the IPF as target variable. With the third method, the temporal scaling properties of IPF series based on the hypothesis of piece wise simple scaling are investigated for 3 different flow gauges with 15 min data and then utilized to estimate the IPF for all gauges in the area. The study region is the Aller-Leine river basin in northern Germany with 45 stream flow gauges. Cross validation results from the three presented models show good performance in reproducing the peak flow and the potential to be used in other catchment. The simple regressions are the easiest to apply given enough peak flow data, the scaling method is the most efficient one among these three models but stepwise multiple linear regressions gives the best results compared with the other two methods.
Petty Cash. Student's Manual and Instructor's Manual.
ERIC Educational Resources Information Center
McElveen, Peggy C.
Both a set of student materials and an instructor's manual on maintaining a petty cash fund are included in this packet, which is one of a series. The student materials include a pretest, five learning activities which contain the information and forms needed to complete the activities, a student self-check, with each activity, and a posttest. The…
24 CFR 220.842 - Cash adjustment.
Code of Federal Regulations, 2012 CFR
2012-04-01
... INSURANCE AND INSURED IMPROVEMENT LOANS FOR URBAN RENEWAL AND CONCENTRATED DEVELOPMENT AREAS Contract Rights... 24 Housing and Urban Development 2 2012-04-01 2012-04-01 false Cash adjustment. 220.842 Section 220.842 Housing and Urban Development Regulations Relating to Housing and Urban Development...
24 CFR 220.842 - Cash adjustment.
Code of Federal Regulations, 2010 CFR
2010-04-01
... INSURANCE AND INSURED IMPROVEMENT LOANS FOR URBAN RENEWAL AND CONCENTRATED DEVELOPMENT AREAS Contract Rights... 24 Housing and Urban Development 2 2010-04-01 2010-04-01 false Cash adjustment. 220.842 Section 220.842 Housing and Urban Development Regulations Relating to Housing and Urban Development...
24 CFR 220.842 - Cash adjustment.
Code of Federal Regulations, 2013 CFR
2013-04-01
... INSURANCE AND INSURED IMPROVEMENT LOANS FOR URBAN RENEWAL AND CONCENTRATED DEVELOPMENT AREAS Contract Rights... 24 Housing and Urban Development 2 2013-04-01 2013-04-01 false Cash adjustment. 220.842 Section 220.842 Housing and Urban Development Regulations Relating to Housing and Urban Development...
24 CFR 220.842 - Cash adjustment.
Code of Federal Regulations, 2011 CFR
2011-04-01
... INSURANCE AND INSURED IMPROVEMENT LOANS FOR URBAN RENEWAL AND CONCENTRATED DEVELOPMENT AREAS Contract Rights... 24 Housing and Urban Development 2 2011-04-01 2011-04-01 false Cash adjustment. 220.842 Section 220.842 Housing and Urban Development Regulations Relating to Housing and Urban Development...
24 CFR 220.842 - Cash adjustment.
Code of Federal Regulations, 2014 CFR
2014-04-01
... INSURANCE AND INSURED IMPROVEMENT LOANS FOR URBAN RENEWAL AND CONCENTRATED DEVELOPMENT AREAS Contract Rights... 24 Housing and Urban Development 2 2014-04-01 2014-04-01 false Cash adjustment. 220.842 Section 220.842 Housing and Urban Development Regulations Relating to Housing and Urban Development...
7 CFR 277.7 - Cash depositories.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 7 Agriculture 4 2010-01-01 2010-01-01 false Cash depositories. 277.7 Section 277.7 Agriculture Regulations of the Department of Agriculture (Continued) FOOD AND NUTRITION SERVICE, DEPARTMENT OF AGRICULTURE FOOD STAMP AND FOOD DISTRIBUTION PROGRAM PAYMENTS OF CERTAIN ADMINISTRATIVE COSTS OF STATE...
7 CFR 277.7 - Cash depositories.
Code of Federal Regulations, 2014 CFR
2014-01-01
... 7 Agriculture 4 2014-01-01 2014-01-01 false Cash depositories. 277.7 Section 277.7 Agriculture Regulations of the Department of Agriculture (Continued) FOOD AND NUTRITION SERVICE, DEPARTMENT OF AGRICULTURE FOOD STAMP AND FOOD DISTRIBUTION PROGRAM PAYMENTS OF CERTAIN ADMINISTRATIVE COSTS OF STATE...
7 CFR 277.7 - Cash depositories.
Code of Federal Regulations, 2011 CFR
2011-01-01
... 7 Agriculture 4 2011-01-01 2011-01-01 false Cash depositories. 277.7 Section 277.7 Agriculture Regulations of the Department of Agriculture (Continued) FOOD AND NUTRITION SERVICE, DEPARTMENT OF AGRICULTURE FOOD STAMP AND FOOD DISTRIBUTION PROGRAM PAYMENTS OF CERTAIN ADMINISTRATIVE COSTS OF STATE...
7 CFR 277.7 - Cash depositories.
Code of Federal Regulations, 2012 CFR
2012-01-01
... 7 Agriculture 4 2012-01-01 2012-01-01 false Cash depositories. 277.7 Section 277.7 Agriculture Regulations of the Department of Agriculture (Continued) FOOD AND NUTRITION SERVICE, DEPARTMENT OF AGRICULTURE FOOD STAMP AND FOOD DISTRIBUTION PROGRAM PAYMENTS OF CERTAIN ADMINISTRATIVE COSTS OF STATE...
7 CFR 277.7 - Cash depositories.
Code of Federal Regulations, 2013 CFR
2013-01-01
... 7 Agriculture 4 2013-01-01 2013-01-01 false Cash depositories. 277.7 Section 277.7 Agriculture Regulations of the Department of Agriculture (Continued) FOOD AND NUTRITION SERVICE, DEPARTMENT OF AGRICULTURE FOOD STAMP AND FOOD DISTRIBUTION PROGRAM PAYMENTS OF CERTAIN ADMINISTRATIVE COSTS OF STATE...
Cash Management Program Reaps Financial Rewards.
ERIC Educational Resources Information Center
Saylor, Joan Nesenkar
1984-01-01
Basic components of a New Jersey district's profitable cash management program include consolidating funds using a negotiated bank agreement, a short term investment policy, accurate flowcharts for precise planning, and revenue and expenditure analysis. Data collection and analysis and the alternative of using a bank service agreement are…
Why Cash "Doesn't" Motivate...
ERIC Educational Resources Information Center
Freifeld, Lorri
2011-01-01
If money is the root of all evil, is it also the root of all motivation? When talking about workplace performance and training, the experts' consensus is a resounding "No." This article discusses why cash doesn't motivate everyone all the time when it comes to workplace performance and training and takes a look at what does.
Easy come-easy go divisible cash
Chan, A.; Tsiounis, Y.; Frankel, Y.
1996-10-16
Recently, there has been an interest in making electronic cash protocols more practical for electronic commerce by developing e-cash which is divisible (e.g., a coin which can be spent incrementally but total purchases are limited to the monetary value of the coin). In Crypto`95, T. Okamoto presented the first practical divisible, untraceable, off-line e-cash scheme, which requires only O(log N) computations for each of the withdrawal, payment and deposit procedures, where N = (total coin value)/(smallest divisible unit). However, Okamoto`s set-up procedure is quite inefficient (on the order of 4,000 multi-exponentiations and depending on the size of the RSA modulus). The authors formalize the notion of range-bounded commitment, originally used in Okamoto`s account establishment protocol, and present a very efficient instantiation which allows one to construct the first truly efficient divisible e-cash system. The scheme only requires the equivalent of one (1) exponentiation for set-up, less than 2 exponentiations for withdrawal and around 20 for payment, while the size of the coin remains about 300 Bytes. Hence, the withdrawal protocol is 3 orders of magnitude faster than Okamoto`s, while the rest of the system remains equally efficient, allowing for implementation in smart-cards. Similar to Okamoto`s, the scheme is based on proofs whose cryptographic security assumptions are theoretically clarified.
12 CFR 952.5 - Community Investment Cash Advance Programs.
Code of Federal Regulations, 2011 CFR
2011-01-01
... 12 Banks and Banking 7 2011-01-01 2011-01-01 false Community Investment Cash Advance Programs. 952... OFF-BALANCE SHEET ITEMS COMMUNITY INVESTMENT CASH ADVANCE PROGRAMS § 952.5 Community Investment Cash... targeted community lending at the appropriate targeted income levels. (3) Each Bank may offer RDF...
12 CFR 952.5 - Community Investment Cash Advance Programs.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 12 Banks and Banking 7 2010-01-01 2010-01-01 false Community Investment Cash Advance Programs. 952... OFF-BALANCE SHEET ITEMS COMMUNITY INVESTMENT CASH ADVANCE PROGRAMS § 952.5 Community Investment Cash... targeted community lending at the appropriate targeted income levels. (3) Each Bank may offer RDF...
Title IV Cash Management Life Cycle Training. Participant's Guide.
ERIC Educational Resources Information Center
Department of Education, Washington, DC.
This participant's guide includes: "Introduction: Welcome to Cash Management Life Cycle Training"; "Module 1: Review of Cash Management Principles" (cash management overview and activity); "Module 2: Common Origination and Disbursement (COD) System Overview" (e.g., full participants and phase-in participants, COD access, and features and…
31 CFR 206.6 - Cash management planning and review.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 31 Money and Finance:Treasury 2 2011-07-01 2011-07-01 false Cash management planning and review...) FISCAL SERVICE, DEPARTMENT OF THE TREASURY FINANCIAL MANAGEMENT SERVICE MANAGEMENT OF FEDERAL AGENCY RECEIPTS, DISBURSEMENTS, AND OPERATION OF THE CASH MANAGEMENT IMPROVEMENTS FUND § 206.6 Cash...
18 CFR 154.306 - Cash working capital.
Code of Federal Regulations, 2011 CFR
2011-04-01
... 18 Conservation of Power and Water Resources 1 2011-04-01 2011-04-01 false Cash working capital... Changes § 154.306 Cash working capital. A natural gas company that files a tariff change under this part may not receive a cash working capital adjustment to its rate base unless the company or...
18 CFR 154.306 - Cash working capital.
Code of Federal Regulations, 2010 CFR
2010-04-01
... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Cash working capital... Changes § 154.306 Cash working capital. A natural gas company that files a tariff change under this part may not receive a cash working capital adjustment to its rate base unless the company or...
12 CFR 1292.5 - Community Investment Cash Advance Programs.
Code of Federal Regulations, 2014 CFR
2014-01-01
... 12 Banks and Banking 10 2014-01-01 2014-01-01 false Community Investment Cash Advance Programs... COMMUNITY INVESTMENT CASH ADVANCE PROGRAMS § 1292.5 Community Investment Cash Advance Programs. (a) In... shall offer a CIP to provide financing for housing projects and for eligible targeted community...
12 CFR 952.5 - Community Investment Cash Advance Programs.
Code of Federal Regulations, 2012 CFR
2012-01-01
... 12 Banks and Banking 8 2012-01-01 2012-01-01 false Community Investment Cash Advance Programs. 952... OFF-BALANCE SHEET ITEMS COMMUNITY INVESTMENT CASH ADVANCE PROGRAMS § 952.5 Community Investment Cash... targeted community lending at the appropriate targeted income levels. (3) Each Bank may offer RDF...
12 CFR 952.5 - Community Investment Cash Advance Programs.
Code of Federal Regulations, 2013 CFR
2013-01-01
... 12 Banks and Banking 8 2013-01-01 2013-01-01 false Community Investment Cash Advance Programs. 952... OFF-BALANCE SHEET ITEMS COMMUNITY INVESTMENT CASH ADVANCE PROGRAMS § 952.5 Community Investment Cash... targeted community lending at the appropriate targeted income levels. (3) Each Bank may offer RDF...
25 CFR 166.605 - Are cash performance bonds refunded?
Code of Federal Regulations, 2011 CFR
2011-04-01
... 25 Indians 1 2011-04-01 2011-04-01 false Are cash performance bonds refunded? 166.605 Section 166.605 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR LAND AND WATER GRAZING PERMITS Bonding and Insurance Requirements § 166.605 Are cash performance bonds refunded? If the cash...
18 CFR 141.500 - Cash management programs.
Code of Federal Regulations, 2012 CFR
2012-04-01
... 18 Conservation of Power and Water Resources 1 2012-04-01 2012-04-01 false Cash management... OF 1978 STATEMENTS AND REPORTS (SCHEDULES) § 141.500 Cash management programs. Public utilities and... and § 141.1 or § 141.2 of this title that participate in cash management programs must file...
18 CFR 357.5 - Cash management programs.
Code of Federal Regulations, 2011 CFR
2011-04-01
... changes to the cash management agreement must be filed with the Commission within 10 days of the change. ... 18 Conservation of Power and Water Resources 1 2011-04-01 2011-04-01 false Cash management...: CARRIERS SUBJECT TO PART I OF THE INTERSTATE COMMERCE ACT § 357.5 Cash management programs. Oil...
18 CFR 141.500 - Cash management programs.
Code of Federal Regulations, 2011 CFR
2011-04-01
... 18 Conservation of Power and Water Resources 1 2011-04-01 2011-04-01 false Cash management... OF 1978 STATEMENTS AND REPORTS (SCHEDULES) § 141.500 Cash management programs. Public utilities and... and § 141.1 or § 141.2 of this title that participate in cash management programs must file...
18 CFR 357.5 - Cash management programs.
Code of Federal Regulations, 2012 CFR
2012-04-01
... changes to the cash management agreement must be filed with the Commission within 10 days of the change. ... 18 Conservation of Power and Water Resources 1 2012-04-01 2012-04-01 false Cash management...: CARRIERS SUBJECT TO PART I OF THE INTERSTATE COMMERCE ACT § 357.5 Cash management programs. Oil...
18 CFR 141.500 - Cash management programs.
Code of Federal Regulations, 2010 CFR
2010-04-01
... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Cash management... OF 1978 STATEMENTS AND REPORTS (SCHEDULES) § 141.500 Cash management programs. Public utilities and... and § 141.1 or § 141.2 of this title that participate in cash management programs must file...
18 CFR 357.5 - Cash management programs.
Code of Federal Regulations, 2010 CFR
2010-04-01
... changes to the cash management agreement must be filed with the Commission within 10 days of the change. ... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Cash management...: CARRIERS SUBJECT TO PART I OF THE INTERSTATE COMMERCE ACT § 357.5 Cash management programs. Oil...
18 CFR 367.1360 - Account 136, Temporary cash investments.
Code of Federal Regulations, 2014 CFR
2014-04-01
... cash investments. 367.1360 Section 367.1360 Conservation of Power and Water Resources FEDERAL ENERGY... cash investments. (a) This account must include the book cost of investments, such as demand and time... similar investments, acquired for the purpose of temporarily investing cash. (b) This account must...
Cash receipts process for HANDI 2000 business management system
Wilson, D.
1998-08-24
All Fluor Daniel Hanford cash receipts are processed in the Operations Travel System. There are five types of cash receipts. Depending on the type, the receipt may be processed by APM OTS, Site-Wide Savings, retirement Information System, or PeopleSoft Benefits System. Regardless of the source, all cash received is eventually forwarded to Treasure for deposit into the bank.
40 CFR 35.3160 - Cash draw rules.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 1 2011-07-01 2011-07-01 false Cash draw rules. 35.3160 Section 35.3160 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY GRANTS AND OTHER FEDERAL ASSISTANCE STATE AND LOCAL ASSISTANCE State Water Pollution Control Revolving Funds § 35.3160 Cash draw rules. (a) Loans. The State may draw cash from the LOC...
Nonlinear Green's function method for unsteady transonic flows
NASA Technical Reports Server (NTRS)
Tseng, K.; Morino, L.
1982-01-01
Advantages to employing Green's function in describing unsteady three-dimensional transonic flows are explored. The development of the function for application to linear subsonic and supersonic unsteady aerodynamics is reviewed. It is shown that unique solutions are possible for external flows, with all functional expressions being defined in Prandtl-Glauert space. The development of methods of using the Green's function for transonic flows is traced, noting the necessity of including the effects of significant nonlinear terms. The steady-state problem is considered to demonstrate the shock-capturing ability of the method and the usefulness of the function in the incompressible, subsonic, transonic, and supersonic areas of potential unsteady three-dimensional flows around complex configurations. Computational time is asserted to be an order of magnitude less than with finite difference methods.
A Fast Estimation Method of Railway Passengers' Flow
NASA Astrophysics Data System (ADS)
Nagasaki, Yusaku; Asuka, Masashi; Komaya, Kiyotoshi
To evaluate a train schedule from the viewpoint of passengers' convenience, it is important to know each passenger's choice of trains and transfer stations to arrive at his/her destination. Because of difficulties of measuring such passengers' behavior, estimation methods of railway passengers' flow are proposed to execute such an evaluation. However, a train schedule planning system equipped with those methods is not practical due to necessity of much time to complete the estimation. In this article, the authors propose a fast passengers' flow estimation method that employs features of passengers' flow graph using preparative search based on each train's arrival time at each station. And the authors show the results of passengers' flow estimation applied on a railway in an urban area.
NASA Technical Reports Server (NTRS)
Hamrick, Joseph T; Ginsburg, Ambrose; Osborn, Walter M
1952-01-01
A method is presented for analysis of the compressible flow between the hub and the shroud of mixed-flow impellers of arbitrary design. Axial symmetry was assumed, but the forces in the meridional (hub to shroud) plane, which are derived from tangential pressure gradients, were taken into account. The method was applied to an experimental mixed-flow impeller. The analysis of the flow in the meridional plane of the impeller showed that the rotational forces, the blade curvature, and the hub-shroud profile can introduce severe velocity gradients along the hub and the shroud surfaces. Choked flow at the impeller inlet as determined by the analysis was verified by experimental results.
On the no-field method for void time determination in flow field-flow fractionation.
Martin, Michel; Hoyos, Mauricio
2011-07-01
Elution time measurements of colloidal particles injected in a symmetrical flow field-flow fractionation (flow FFF) system when the inlet and outlet cross-flow connections are closed have been performed. This no-field method has been proposed earlier for void time (and void volume) determination in flow FFF Giddings et al. (1977). The elution times observed were much larger than expected on the basis of the channel geometrical volume and the flow rate. In order to explain these discrepancies, a flow model allowing the carrier liquid to flow through the porous walls toward the reservoirs located behind the porous elements and along these reservoirs was developed. The ratio between the observed elution time and expected one is found to depend only on a parameter which is a function of the effective permeability and thickness of the porous elements and of the channel thickness and length. The permeabilities of the frits used in the system were measured. Their values lead to predicted elution times in reasonable agreement with experimental ones, taking into account likely membrane protrusion inside the channel on system assembly. They comfort the basic feature of the flow model, in the no-field case. The carrier liquid mostly bypasses the channel to flow along the system mainly in the reservoir. It flows through the porous walls toward the reservoirs near channel inlet and again through the porous walls from the reservoirs to the channel near channel outlet before exiting the system. In order to estimate the extent of this bypassing process, it is desirable that the hydrodynamic characteristics of the permeable elements (permeability and thickness) are provided by flow FFF manufacturers. The model applies to symmetrical as well as asymmetrical flow FFF systems. PMID:21256498
A semi-probabilistic assessment method for flow slides
NASA Astrophysics Data System (ADS)
van den Ham, G.; Mastbergen, D.; de Groot, M.
2013-12-01
Flow slides in submerged slopes in non-lithified sandy and silty sediments form a major threat for flood defences along (estuary) coastlines and riverbanks in the Netherlands. Such flow slides may result in failure of levees and structures, eventually leading to flooding of the hinterland. Flow slide is a complex failure mechanism that includes both soil mechanical and hydraulic features. Two important sub-mechanisms are static liquefaction and breach flow. Static liquefaction entails the sudden loss of strength of loosely packed saturated sand or silt resulting in a collapse of the sand body. Breach flow is a more superficial process, involving the upslope retrogression of a local steep part of the slope which generates a turbulent sand-water mixture flow along the sand surface of the under water slope. Both mechanisms need a trigger, e.g. local steepening of the slope by erosion or slip failure. Although a breach flow slide generally takes more time than a liquefaction flow slide, both mechanisms result in a flowing sand-water mixture, that eventually resedimentates under a very gentle slope. Therefore in the analysis of historical flow slides it is often not clear to what extent static soil liquefaction and/or breach flow has played a role. In the current Dutch practice the prediction of levee failure due to flow sliding is based on either simple but conservative empirical rules based on documented historical flow slides in which distinction between mentioned sub-mechanisms is disregarded, or rather complex physical-based models describing mechanisms such as static liquefaction or breach flow. It will be presented how both approaches can be combined into a practical, probabilistic method for assessing dike failure due to flow sliding, accounting for uncertainties of the main influence factors. The method has recently been implemented in the so-called Dike Analysis Module (DAM). DAM is a platform for performing semi-automatic stability analyses on a large number
Method, apparatus and system for controlling fluid flow
McMurtrey, Ryan D.; Ginosar, Daniel M.; Burch, Joesph V.
2007-10-30
A system, apparatus and method of controlling the flow of a fluid are provided. In accordance with one embodiment of the present invention, a flow control device includes a valve having a flow path defined therethrough and a valve seat in communication with the flow path with a valve stem disposed in the valve seat. The valve stem and valve seat are cooperatively configured to cause mutual relative linear displacement thereof in response to rotation of the valve stem. A gear member is coupled with the rotary stem and a linear positioning member includes a portion which complementarily engages the gear member. Upon displacement of the linear positioning member along a first axis, the gear member and rotary valve stem are rotated about a second axis and the valve stem and valve seat are mutually linearly displaced to alter the flow of fluid through the valve.
A study of methods to estimate debris flow velocity
Prochaska, A.B.; Santi, P.M.; Higgins, J.D.; Cannon, S.H.
2008-01-01
Debris flow velocities are commonly back-calculated from superelevation events which require subjective estimates of radii of curvature of bends in the debris flow channel or predicted using flow equations that require the selection of appropriate rheological models and material property inputs. This research investigated difficulties associated with the use of these conventional velocity estimation methods. Radii of curvature estimates were found to vary with the extent of the channel investigated and with the scale of the media used, and back-calculated velocities varied among different investigated locations along a channel. Distinct populations of Bingham properties were found to exist between those measured by laboratory tests and those back-calculated from field data; thus, laboratory-obtained values would not be representative of field-scale debris flow behavior. To avoid these difficulties with conventional methods, a new preliminary velocity estimation method is presented that statistically relates flow velocity to the channel slope and the flow depth. This method presents ranges of reasonable velocity predictions based on 30 previously measured velocities. ?? 2008 Springer-Verlag.
Social acceptability and perceived impact of a community-led cash transfer programme in Zimbabwe
2013-01-01
Background Cash transfer programmes are increasingly recognised as promising and scalable interventions that can promote the health and development of children. However, concerns have been raised about the potential for cash transfers to contribute to social division, jealousy and conflict at a community level. Against this background, and in our interest to promote community participation in cash transfer programmes, we examine local perceptions of a community-led cash transfer programme in Eastern Zimbabwe. Methods We collected and analysed data from 35 individual interviews and three focus group discussions, involving 24 key informants (community committee members and programme implementers), 24 cash transfer beneficiaries, of which four were youth, and 14 non-beneficiaries. Transcripts were subjected to thematic analysis and coding to generate concepts. Results Study participants described the programme as participatory, fair and transparent – reducing the likelihood of jealousy. The programme was perceived to have had a substantial impact on children’s health and education, primarily through aiding parents and guardians to better cater for their children’s needs. Moreover, participants alluded to the potential of the programme to facilitate more transformational change, for example by enabling families to invest money in assets and income generating activities and by promoting a community-wide sense of responsibility for the support of orphaned and vulnerable children. Conclusion Community participation, combined with the perceived impact of the cash transfer programme, led community members to speak enthusiastically about the programme. We conclude that community-led cash transfer programmes have the potential to open up for possibilities of participation and community agency that enable social acceptability and limit social divisiveness. PMID:23587136
Boccia, D.; Hargreaves, J.; Lönnroth, K.; Jaramillo, E.; Weiss, J.; Uplekar, M.; Porter, J. D. H.; Evans, C. A.
2011-01-01
OBJECTIVE To quantify the impact of cash transfer and microfinance interventions on a selected list of tuberculosis (TB) risk factors and assess their potential role in supporting TB control. DATA SOURCE Published and unpublished references identified from clinical and social electronic databases, grey literature and web sites. METHODS Eligible interventions had to be conducted in middle- or low-income countries and document an impact evaluation on any of the following outcomes: 1) TB or other respiratory infections; 2) household socio-economic position; and 3) factors mediating the association between low household socio-economic position and TB, including inadequate health-seeking behaviours, food insecurity and biological TB risk factors such as human immunodeficiency virus (HIV) and adult malnutrition. Interventions targeting special populations were excluded. RESULTS Fifteen cash transfer schemes (four unconditional and 11 conditional) and seven microfinance programmes met the eligibility criteria. No intervention addressed TB or any other respiratory infection. Of 11 cash transfer and four microfinance interventions, respectively seven and four reported a positive impact on indicators of economic well-being. A positive impact on household food security was documented in respectively eight of nine and three of five cash transfer and microfinance interventions. Improved health care access was documented respectively in 10 of 12 cash transfer and four of five microfinance interventions. The only intervention evaluating impact on HIV incidence was a microfinance project that found no effect. No cash transfer or microfinance interventions had an impact on adult malnutrition. CONCLUSIONS Cash transfer and microfinance interventions can positively impact TB risk factors. Evaluation studies are urgently needed to assess the impact of these social protection interventions on actual TB indicators. PMID:21740658
Multiple Denominations in E-cash with Compact Transaction Data
NASA Astrophysics Data System (ADS)
Canard, Sébastien; Gouget, Aline
We present a new construction of divisible e-cash that makes use of 1) a new generation method of the binary tree of keys; 2) a new way of using bounded accumulators. The transaction data sent to the merchant has a constant number of bits while spending a monetary value 2ℓ. Moreover, the spending protocol does not require complex zero-knowledge proofs of knowledge such as proofs about double discrete logarithms. We then propose the first strongly anonymous scheme with standard unforgeability requirement and realistic generation parameters while improving the efficiency of the spending phase.
A Semi-Implicit Lattice Method for Simulating Flow
Rector, David R.; Stewart, Mark L.
2010-09-20
We propose a new semi-implicit lattice numerical method for modeling fluid flow that depends only on local primitive variable information (density, pressure, velocity) and not on relaxed upstream distribution function values. This method has the potential for reducing parallel communication and permitting larger time steps compared to the lattice Boltzmann method. The lid-driven cavity is modeled to demonstrate the accuracy of the method.
Clearance gap flow: simulations by discontinuous Galerkin method and experiments
NASA Astrophysics Data System (ADS)
Prausová, Helena; Bublík, Ondřej; Vimmr, Jan; Luxa, Martin; Hála, Jindřich
2015-05-01
Compressible viscous fluid flow in a narrow gap formed by two parallel plates in distance of 2 mm is investigated numerically and experimentally. Pneumatic and optical methods were used to obtain distribution of static to stagnation pressure ratio along the channel axis and interferograms including the free outflow behind the channel. Modern developing discontinuous Galerkin finite element method is implemented for numerical simulation of the fluid flow. The goal to make progress in knowledge of compressible viscous fluid flow characteristic phenomena in minichannels is satisfied by finding a suitable approach to this problem. Laminar, turbulent and transitional flow regime is examined and a good agreement of experimental and numerical results is achieved using γ - Reθt transition model.
Modeling Electrokinetic Flows by the Smoothed Profile Method
Luo, Xian; Beskok, Ali; Karniadakis, George Em
2010-01-01
We propose an efficient modeling method for electrokinetic flows based on the Smoothed Profile Method (SPM) [1–4] and spectral element discretizations. The new method allows for arbitrary differences in the electrical conductivities between the charged surfaces and the the surrounding electrolyte solution. The electrokinetic forces are included into the flow equations so that the Poisson-Boltzmann and electric charge continuity equations are cast into forms suitable for SPM. The method is validated by benchmark problems of electroosmotic flow in straight channels and electrophoresis of charged cylinders. We also present simulation results of electrophoresis of charged microtubules, and show that the simulated electrophoretic mobility and anisotropy agree with the experimental values. PMID:20352076
Topography Modeling in Atmospheric Flows Using the Immersed Boundary Method
NASA Technical Reports Server (NTRS)
Ackerman, A. S.; Senocak, I.; Mansour, N. N.; Stevens, D. E.
2004-01-01
Numerical simulation of flow over complex geometry needs accurate and efficient computational methods. Different techniques are available to handle complex geometry. The unstructured grid and multi-block body-fitted grid techniques have been widely adopted for complex geometry in engineering applications. In atmospheric applications, terrain fitted single grid techniques have found common use. Although these are very effective techniques, their implementation, coupling with the flow algorithm, and efficient parallelization of the complete method are more involved than a Cartesian grid method. The grid generation can be tedious and one needs to pay special attention in numerics to handle skewed cells for conservation purposes. Researchers have long sought for alternative methods to ease the effort involved in simulating flow over complex geometry.
Modeling groundwater flow by lattice Boltzmann method in curvilinear coordinates
NASA Astrophysics Data System (ADS)
Budinski, Ljubomir; Fabian, Julius; Stipic, Matija
2015-07-01
In order to promote the use of the lattice Boltzmann method (LBM) for the simulation of isotropic groundwater flow in a confined aquifer with arbitrary geometry, Poisson's equation was transformed into a curvilinear coordinate system. With the metric function between the physical and the computational domain established, Poisson's equation written in Cartesian coordinates was transformed in curvilinear coordinates. Following, the appropriate equilibrium function for the D2Q9 square lattice has been defined. The resulting curvilinear formulation of the LBM for groundwater flow is capable of modeling flow in domains of complex geometry with the opportunity of local refining/coarsening of the computational mesh corresponding to the complexity of the flow pattern and the required accuracy. Since the proposed form of the LBM uses the transformed equation of flow implemented in the equilibrium function, finding a solution does not require supplementary procedures along the curvilinear boundaries, nor in the zones requiring mesh density adjustments. Thus, the basic concept of the LBM is completely maintained. The improvement of the proposed LBM over the previously published classical methods is completely verified by three examples with analytical solutions. The results demonstrate the advantages of the proposed curvilinear LBM in modeling groundwater flow in complex flow domains.
Combustor flow computations in general coordinates with a multigrid method
NASA Astrophysics Data System (ADS)
Shyy, Wei; Braaten, Mark E.
The computational approach presented for single-phase combusting turbulent flowfields balances the requirements of complex physical and chemical flow interactions with those of resolving the three-dimensional geometrical constraints of the combustor contours, film cooling slots, and circular dilution holes. Attention is given to the three-dimensional grid-generation algorithm, the two-dimensional adaptive grid method applied to recirculating turbulent reacting flows, and theory/data assessments for three-dimensional combusting flows in an annular gas turbine combustor.
Fiber optic liquid mass flow sensor and method
NASA Technical Reports Server (NTRS)
Korman, Valentin (Inventor); Gregory, Don Allen (Inventor); Wiley, John T. (Inventor); Pedersen, Kevin W. (Inventor)
2010-01-01
A method and apparatus are provided for sensing the mass flow rate of a fluid flowing through a pipe. A light beam containing plural individual wavelengths is projected from one side of the pipe across the width of the pipe so as to pass through the fluid under test. Fiber optic couplers located at least two positions on the opposite side of the pipe are used to detect the light beam. A determination is then made of the relative strengths of the light beam for each wavelength at the at least two positions and based at least in part on these relative strengths, the mass flow rate of the fluid is determined.
Assessment of nonequilibrium radiation computation methods for hypersonic flows
NASA Technical Reports Server (NTRS)
Sharma, Surendra
1993-01-01
The present understanding of shock-layer radiation in the low density regime, as appropriate to hypersonic vehicles, is surveyed. Based on the relative importance of electron excitation and radiation transport, the hypersonic flows are divided into three groups: weakly ionized, moderately ionized, and highly ionized flows. In the light of this division, the existing laboratory and flight data are scrutinized. Finally, an assessment of the nonequilibrium radiation computation methods for the three regimes in hypersonic flows is presented. The assessment is conducted by comparing experimental data against the values predicted by the physical model.
An implicit Lagrangian lattice Boltzmann method for the compressible flows
NASA Astrophysics Data System (ADS)
Yan, Guangwu; Dong, Yinfeng; Liu, Yanhong
2006-08-01
In this paper, we propose a new Lagrangian lattice Boltzmann method (LBM) for simulating the compressible flows. The new scheme simulates fluid flows based on the displacement distribution functions. The compressible flows, such as shock waves and contact discontinuities are modelled by using Lagrangian LBM. In this model, we select the element in the Lagrangian coordinate to satisfy the basic fluid laws. This model is a simpler version than the corresponding Eulerian coordinates, because the convection term of the Euler equations disappears. The numerical simulations conform to classical results.
AN IMMERSED BOUNDARY METHOD FOR COMPLEX INCOMPRESSIBLE FLOWS
An immersed boundary method for time-dependant, three- dimensional, incompressible flows is presented in this paper. The incompressible Navier-Stokes equations are discretized using a low-diffusion flux splitting method for the inviscid fluxes and a second order central differenc...
The flow curvature method applied to canard explosion
NASA Astrophysics Data System (ADS)
Ginoux, Jean-Marc; Llibre, Jaume
2011-11-01
The aim of this work is to establish that the bifurcation parameter value leading to a canard explosion in dimension 2 obtained by the so-called geometric singular perturbation method can be found according to the flow curvature method. This result will be then exemplified with the classical Van der Pol oscillator.
Study of the Transition Flow Regime using Monte Carlo Methods
NASA Technical Reports Server (NTRS)
Hassan, H. A.
1999-01-01
This NASA Cooperative Agreement presents a study of the Transition Flow Regime Using Monte Carlo Methods. The topics included in this final report are: 1) New Direct Simulation Monte Carlo (DSMC) procedures; 2) The DS3W and DS2A Programs; 3) Papers presented; 4) Miscellaneous Applications and Program Modifications; 5) Solution of Transitional Wake Flows at Mach 10; and 6) Turbulence Modeling of Shock-Dominated Fows with a k-Enstrophy Formulation.
Compressible flow calculations employing the Galerkin/least-squares method
NASA Technical Reports Server (NTRS)
Shakib, F.; Hughes, T. J. R.; Johan, Zdenek
1989-01-01
A multielement group, domain decomposition algorithm is presented for solving linear nonsymmetric systems arising in the finite-element analysis of compressible flows employing the Galerkin/least-squares method. The iterative strategy employed is based on the generalized minimum residual (GMRES) procedure originally proposed by Saad and Shultz. Two levels of preconditioning are investigated. Applications to problems of high-speed compressible flow illustrate the effectiveness of the scheme.
Numerical simulation methods for the Rouse model in flow
NASA Astrophysics Data System (ADS)
Howard, Michael P.; Milner, Scott T.
2011-11-01
Simulation of the Rouse model in flow underlies a great variety of numerical investigations of polymer dynamics, in both entangled melts and solutions and in dilute solution. Typically a simple explicit stochastic Euler method is used to evolve the Rouse model. Here we compare this approach to an operator splitting method, which splits the evolution operator into stochastic linear and deterministic nonlinear parts and takes advantage of an analytical solution for the linear Rouse model in terms of the noise history. We show that this splitting method has second-order weak convergence, whereas the Euler method has only first-order weak convergence. Furthermore, the splitting method is unconditionally stable, in contrast to the limited stability range of the Euler method. Similar splitting methods are applicable to a broad class of problems in stochastic dynamics in which noise competes with ordering and flow to determine steady-state order parameter structures.
Determination of renal blood flow by thermodilution method.
Leivestad, T; Brodwall, E K; Simonsen, S
1978-09-01
The single bolus thermodilution method for measurement of renal vein blood flow was tested. In model experiments the thermodilution method was compared with graduated cylinder measurements over a flow range from 50 to 1050 ml/min. There was a good correlation between the two methods (r = 0.98) with a mean of differences of 5.2%. In eighteen patients measurements were performed in duplicate in thirty-one renal veins. Comparison was made between the first (x) and second (u) measurement--performed within 3 min. The correlation between the two was very good (r = 0.99; y = 1.03x - 11.48). In twelve patients bilateral renal vein blood flow measurements were performed simultaneous to blood flow measurement by PAH clearance. The correlation between total flow measured by thermodilution (y) and by the clearance method (x) was good (r = 0.98; y = 0.79x + 221). It is concluded that the thermodilution method requires catheterization of the renal veins, but is otherwise simple to perform, is inexpensive and gives reliable results. It is particularly advantageous when repeated measurements in the study of acute changes in renal haemodynamics is desirable. PMID:705231
A nonintrusive method of quantifying flow visualization data in vortex flow fields
NASA Astrophysics Data System (ADS)
Sei, Vincent J.
1994-12-01
The High Angle of Attack Research Vehicle (HARV) as well as other similar flight test aircraft have been using smoke flow visualization techniques to characterize the vortex flow created by leading edge extensions and the forebody. With the advent of video measurement techniques, this type of flow visualization can not only provide a qualitative assessment of the flow but also a quantitative measure to be used to validate computational fluid dynamic codes and wind tunnel test. One of the major drawbacks to employing video imaging was the introduction of false motion due to camera movement in flight. A relative motion approach using fixed targets along with the flow visualization scheme was utilized to remove unwanted motion. The relative motion algorithm was tested using a laboratory test setup where cameras underwent both translational and rotational motion to simulate both wing bending and torsion. The method was effective in removing both motions with only a slight loss of accuracy.
Hoskinson, Reed L.; Svoboda, John M.; Bauer, William F.; Elias, Gracy
2008-05-06
A method and apparatus is provided for monitoring a flow path having plurality of different solid components flowing therethrough. For example, in the harvesting of a plant material, many factors surrounding the threshing, separating or cleaning of the plant material and may lead to the inadvertent inclusion of the component being selectively harvested with residual plant materials being discharged or otherwise processed. In accordance with the present invention the detection of the selectively harvested component within residual materials may include the monitoring of a flow path of such residual materials by, for example, directing an excitation signal toward of flow path of material and then detecting a signal initiated by the presence of the selectively harvested component responsive to the excitation signal. The detected signal may be used to determine the presence or absence of a selected plant component within the flow path of residual materials.
Gpu Implementation of Preconditioning Method for Low-Speed Flows
NASA Astrophysics Data System (ADS)
Zhang, Jiale; Chen, Hongquan
2016-06-01
An improved preconditioning method for low-Mach-number flows is implemented on a GPU platform. The improved preconditioning method employs the fluctuation of the fluid variables to weaken the influence of accuracy caused by the truncation error. The GPU parallel computing platform is implemented to accelerate the calculations. Both details concerning the improved preconditioning method and the GPU implementation technology are described in this paper. Then a set of typical low-speed flow cases are simulated for both validation and performance analysis of the resulting GPU solver. Numerical results show that dozens of times speedup relative to a serial CPU implementation can be achieved using a single GPU desktop platform, which demonstrates that the GPU desktop can serve as a cost-effective parallel computing platform to accelerate CFD simulations for low-Speed flows substantially.
A multi-domain method for subsonic viscous flows
NASA Technical Reports Server (NTRS)
Chan, Daniel C.; Sindir, Munir M.
1992-01-01
We have developed a Schwarz type domain decomposition method for a pressure base, two- and three-dimensional Navier-Stokes solver. This technique allows one to partition a flow path, which can be characterized by complex geometry and/or complicated flow physics, into smaller sub-domains according to the local geometric simplicity or estimated flow scales. We can, then, sweep the sub-domains in some order and solve the Navier-Stokes equations using as boundary conditions, along the domain interfaces, the Dirichlet conditions which are taken from the most recent update of the solution in the adjacent neighboring domains. With this technique, one can minimize the adverse effects caused by grid skewness and the stiffness problem caused by disparate flow scales. Here, we report the results of a few fundamental flow cases to demonstrate that a judicious use of the multi-domain method can offer a significant convergence acceleration over the traditional one-domain method. This method can be extended to exploit the architecture of a parallel computer to further improve the speed.
Electron-Beam Diagnostic Methods for Hypersonic Flow Diagnostics
NASA Technical Reports Server (NTRS)
1994-01-01
The purpose of this work was the evaluation of the use of electron-bean fluorescence for flow measurements during hypersonic flight. Both analytical and numerical models were developed in this investigation to evaluate quantitatively flow field imaging concepts based upon the electron beam fluorescence technique for use in flight research and wind tunnel applications. Specific models were developed for: (1) fluorescence excitation/emission for nitrogen, (2) rotational fluorescence spectrum for nitrogen, (3) single and multiple scattering of electrons in a variable density medium, (4) spatial and spectral distribution of fluorescence, (5) measurement of rotational temperature and density, (6) optical filter design for fluorescence imaging, and (7) temperature accuracy and signal acquisition time requirements. Application of these models to a typical hypersonic wind tunnel flow is presented. In particular, the capability of simulating the fluorescence resulting from electron impact ionization in a variable density nitrogen or air flow provides the capability to evaluate the design of imaging instruments for flow field mapping. The result of this analysis is a recommendation that quantitative measurements of hypersonic flow fields using electron-bean fluorescence is a tractable method with electron beam energies of 100 keV. With lower electron energies, electron scattering increases with significant beam divergence which makes quantitative imaging difficult. The potential application of the analytical and numerical models developed in this work is in the design of a flow field imaging instrument for use in hypersonic wind tunnels or onboard a flight research vehicle.
Simulation of turbulent flows using nodal integral method
NASA Astrophysics Data System (ADS)
Singh, Suneet
Nodal methods are the backbone of the production codes for neutron-diffusion and transport equations. Despite their high accuracy, use of these methods for simulation of fluid flow is relatively new. Recently, a modified nodal integral method (MNIM) has been developed for simulation of laminar flows. In view of its high accuracy and efficiency, extension of this method for the simulation of turbulent flows is a logical step forward. In this dissertation, MNIM is extended in two ways to simulate incompressible turbulent flows---a new MNIM is developed for the 2D k-epsilon equations; and 3D, parallel MNIM is developed for direct numerical simulations. Both developments are validated, and test problems are solved. In this dissertation, a new nodal numerical scheme is developed to solve the k-epsilon equations to simulate turbulent flows. The MNIM developed earlier for laminar flow equations is modified to incorporate eddy viscosity approximation and coupled with the above mentioned schemes for the k and epsilon equations, to complete the implementation of the numerical scheme for the k-epsilon model. The scheme developed is validated by comparing the results obtained by the developed method with the results available in the literature obtained using direct numerical simulations (DNS). The results of current simulations match reasonably well with the DNS results. The discrepancies in the results are mainly due to the limitations of the k-epsilon model rather than the deficiency in the developed MNIM. A parallel version of the MNIM is needed to enhance its capability, in order to carry out DNS of the turbulent flows. The parallelization of the scheme, however, presents some unique challenges as dependencies of the discrete variables are different from those that exist in other schemes (for example in finite volume based schemes). Hence, a parallel MNIM (PMNIM) is developed and implemented into a computer code with communication strategies based on the above mentioned
Fully consistent CFD methods for incompressible flow computations
NASA Astrophysics Data System (ADS)
Kolmogorov, D. K.; Shen, W. Z.; Sørensen, N. N.; Sørensen, J. N.
2014-06-01
Nowadays collocated grid based CFD methods are one of the most efficient tools for computations of the flows past wind turbines. To ensure the robustness of the methods they require special attention to the well-known problem of pressure-velocity coupling. Many commercial codes to ensure the pressure-velocity coupling on collocated grids use the so-called momentum interpolation method of Rhie and Chow [1]. As known, the method and some of its widely spread modifications result in solutions, which are dependent of time step at convergence. In this paper the magnitude of the dependence is shown to contribute about 0.5% into the total error in a typical turbulent flow computation. Nevertheless if coarse grids are used, the standard interpolation methods result in much higher non-consistent behavior. To overcome the problem, a recently developed interpolation method, which is independent of time step, is used. It is shown that in comparison to other time step independent method, the method may enhance the convergence rate of the SIMPLEC algorithm up to 25 %. The method is verified using turbulent flow computations around a NACA 64618 airfoil and the roll-up of a shear layer, which may appear in wind turbine wake.
Adaptive computational methods for SSME internal flow analysis
NASA Technical Reports Server (NTRS)
Oden, J. T.
1986-01-01
Adaptive finite element methods for the analysis of classes of problems in compressible and incompressible flow of interest in SSME (space shuttle main engine) analysis and design are described. The general objective of the adaptive methods is to improve and to quantify the quality of numerical solutions to the governing partial differential equations of fluid dynamics in two-dimensional cases. There are several different families of adaptive schemes that can be used to improve the quality of solutions in complex flow simulations. Among these are: (1) r-methods (node-redistribution or moving mesh methods) in which a fixed number of nodal points is allowed to migrate to points in the mesh where high error is detected; (2) h-methods, in which the mesh size h is automatically refined to reduce local error; and (3) p-methods, in which the local degree p of the finite element approximation is increased to reduce local error. Two of the three basic techniques have been studied in this project: an r-method for steady Euler equations in two dimensions and a p-method for transient, laminar, viscous incompressible flow. Numerical results are presented. A brief introduction to residual methods of a-posterior error estimation is also given and some pertinent conclusions of the study are listed.
Nested Cartesian grid method in incompressible viscous fluid flow
NASA Astrophysics Data System (ADS)
Peng, Yih-Ferng; Mittal, Rajat; Sau, Amalendu; Hwang, Robert R.
2010-09-01
In this work, the local grid refinement procedure is focused by using a nested Cartesian grid formulation. The method is developed for simulating unsteady viscous incompressible flows with complex immersed boundaries. A finite-volume formulation based on globally second-order accurate central-difference schemes is adopted here in conjunction with a two-step fractional-step procedure. The key aspects that needed to be considered in developing such a nested grid solver are proper imposition of interface conditions on the nested-block boundaries, and accurate discretization of the governing equations in cells that are with block-interface as a control-surface. The interpolation procedure adopted in the study allows systematic development of a discretization scheme that preserves global second-order spatial accuracy of the underlying solver, and as a result high efficiency/accuracy nested grid discretization method is developed. Herein the proposed nested grid method has been widely tested through effective simulation of four different classes of unsteady incompressible viscous flows, thereby demonstrating its performance in the solution of various complex flow-structure interactions. The numerical examples include a lid-driven cavity flow and Pearson vortex problems, flow past a circular cylinder symmetrically installed in a channel, flow past an elliptic cylinder at an angle of attack, and flow past two tandem circular cylinders of unequal diameters. For the numerical simulations of flows past bluff bodies an immersed boundary (IB) method has been implemented in which the solid object is represented by a distributed body force in the Navier-Stokes equations. The main advantages of the implemented immersed boundary method are that the simulations could be performed on a regular Cartesian grid and applied to multiple nested-block (Cartesian) structured grids without any difficulty. Through the numerical experiments the strength of the solver in effectively
Systems and methods for rebalancing redox flow battery electrolytes
Pham, Ai Quoc; Chang, On Kok
2015-03-17
Various methods of rebalancing electrolytes in a redox flow battery system include various systems using a catalyzed hydrogen rebalance cell configured to minimize the risk of dissolved catalyst negatively affecting flow battery performance. Some systems described herein reduce the chance of catalyst contamination of RFB electrolytes by employing a mediator solution to eliminate direct contact between the catalyzed membrane and the RFB electrolyte. Other methods use a rebalance cell chemistry that maintains the catalyzed electrode at a potential low enough to prevent the catalyst from dissolving.
Improved numerical methods for turbulent viscous recirculating flows
NASA Technical Reports Server (NTRS)
Turan, A.; Vandoormaal, J. P.
1988-01-01
The performance of discrete methods for the prediction of fluid flows can be enhanced by improving the convergence rate of solvers and by increasing the accuracy of the discrete representation of the equations of motion. This report evaluates the gains in solver performance that are available when various acceleration methods are applied. Various discretizations are also examined and two are recommended because of their accuracy and robustness. Insertion of the improved discretization and solver accelerator into a TEACH mode, that has been widely applied to combustor flows, illustrates the substantial gains to be achieved.
Spectral methods for modeling supersonic chemically reacting flow fields
NASA Technical Reports Server (NTRS)
Drummond, J. P.; Hussaini, M. Y.; Zang, T. A.
1985-01-01
A numerical algorithm was developed for solving the equations describing chemically reacting supersonic flows. The algorithm employs a two-stage Runge-Kutta method for integrating the equations in time and a Chebyshev spectral method for integrating the equations in space. The accuracy and efficiency of the technique were assessed by comparison with an existing implicit finite-difference procedure for modeling chemically reacting flows. The comparison showed that the procedure presented yields equivalent accuracy on much coarser grids as compared to the finite-difference procedure with resultant significant gains in computational efficiency.
Continuous-flow free acid monitoring method and system
Strain, J.E.; Ross, H.H.
1980-01-11
A free acid monitoring method and apparatus is provided for continuously measuring the excess acid present in a process stream. The disclosed monitoring system and method is based on the relationship of the partial pressure ratio of water and acid in equilibrium with an acid solution at constant temperature. A portion of the process stream is pumped into and flows through the monitor under the influence of gravity and back to the process stream. A continuous flowing sample is vaporized at a constant temperature and the vapor is subsequently condensed. Conductivity measurements of the condensate produces a nonlinear response function from which the free acid molarity of the sample process stream is determined.
Continuous-flow free acid monitoring method and system
Strain, James E.; Ross, Harley H.
1981-01-01
A free acid monitoring method and apparatus is provided for continuously measuring the excess acid present in a process stream. The disclosed monitoring system and method is based on the relationship of the partial pressure ratio of water and acid in equilibrium with an acid solution at constant temperature. A portion of the process stream is pumped into and flows through the monitor under the influence of gravity and back to the process stream. A continuous flowing sample is vaporized at a constant temperature and the vapor is subsequently condensed. Conductivity measurements of the condensate produces a nonlinear response function from which the free acid molarity of the sample process stream is determined.
Method for selectively controlling flow across slotted liners
Peavy, M.A.; Dees, J.M.
1993-08-31
A process is described for decreasing flow rate across the radial boundary of a selected interval in a well bore containing a slotted liner comprising: placing an explosive and an internally catalyzed resin solution inside an elongated container; locating the elongated container opposite the selected interval in the well bore where flow rate through the slotted liner is to be decreased; firing the explosive; and allowing the resin to cure on the slotted liner before initiating flow through the well. A method is described for decreasing production of unwanted fluids from a horizontal well containing a slotted liner comprising: placing an explosive and an internally catalyzed resin inside an elongated container; placing the elongated container opposite an interval in the horizontal well where unwanted fluid is entering the well bore through the slotted liner; firing the explosive; and permitting the resin to cure on the slotted liner before initiating flow in the well.
Combustor air flow control method for fuel cell apparatus
Clingerman, Bruce J.; Mowery, Kenneth D.; Ripley, Eugene V.
2001-01-01
A method for controlling the heat output of a combustor in a fuel cell apparatus to a fuel processor where the combustor has dual air inlet streams including atmospheric air and fuel cell cathode effluent containing oxygen depleted air. In all operating modes, an enthalpy balance is provided by regulating the quantity of the air flow stream to the combustor to support fuel cell processor heat requirements. A control provides a quick fast forward change in an air valve orifice cross section in response to a calculated predetermined air flow, the molar constituents of the air stream to the combustor, the pressure drop across the air valve, and a look up table of the orifice cross sectional area and valve steps. A feedback loop fine tunes any error between the measured air flow to the combustor and the predetermined air flow.
Finite element method application for turbulent and transitional flow
NASA Astrophysics Data System (ADS)
Sváček, Petr
2016-03-01
This paper is interested in numerical simulations of the interaction of the fluid flow with an airfoil. Particularly, the problem of the turbulent flow around the airfoil with elastic support is considered. The main attention is paid to the numerical approximation of the flow problem using the finite element approximations. The laminar - turbulence transition of the flow on the surface airfoil is considered. The chois of the transition model is discussed. The transition model based on the two equation k-ω turbulence model is used. The structure motion is described with the aid of two degrees of freedom. The motion of the computational domain is treated with the aid of the arbitrary Lagrangian-Eulerian method. Numerical results are shown.
New 3-D flow interpolation method on moving ADCP data
NASA Astrophysics Data System (ADS)
Tsubaki, R.; Kawahara, Y.; Muto, Y.; Fujita, I.
2012-05-01
A simple but accurate interpolation procedure for obtaining the three-dimensional distribution of three-component velocity data, from moving acoustic doppler current profiler (ADCP) observation data, is proposed. For understanding actual flow structure within a river with complex bathymetry, the three-dimensional mean velocity field provides a basic picture of the flow. For obtaining the three-dimensional distribution of three-component velocity data, in this work, anisotropic gridding was introduced in order to remove the random component of measured velocity data caused by the turbulence of the flow and measurement error. A continuity correction based on the pressure equation was used to reduce both random and systematic errors. The accuracy of the developed method was evaluated using three-dimensional flow simulation data from a detached-eddy simulation (DES). By using the procedure developed, the complex flow structure surrounding the spur dikes section in the Uji River was successfully visualized and explored. The proposed method shows superiorities in both accuracy and consistency for the interpolated velocity field, as compared to the kriging and inverse-distance weighted (IDW) methods.
a Spreading Blob Vortex Method for Viscous Bounded Flows.
NASA Astrophysics Data System (ADS)
Rossi, Louis Frank
In this dissertation, I introduce a vortex method that is generally applicable to any two-dimensional, incompressible flow with or without boundaries. This method is deterministic, accurate, convergent, naturally adaptive, geometry independent and fully localized. For viscous flows, the vorticity distribution of each vortex element must evolve in addition to following a Lagrangian trajectory. My method relies upon an idea called core spreading. Core spreading is inconsistent by itself, but I have corrected it with a deterministic process known as "vortex fission" where one "fat" vortex is replaced by several "thinner" ones. Also, I examine rigorously a method for merging many blobs into one. This process maintains smaller problem sizes thus boosting the efficiency of the vortex method. To prove that this corrected core spreading method will converge uniformly, I adapted a continuous formalism to this grid-free scheme. This convergence theory does not rely on any form of grid. I only examine the linear problem where the flow field is specified, and treat the full nonlinear problem as a perturbation of the linear problem. The estimated rate of convergence is demonstrated to be sharp in several examples. Boundary conditions are approximated indirectly. The boundary is decomposed into a collection of small linear segments. I solve the no -slip and no-normal flow conditions simultaneously by superimposing a potential flow and injecting vorticity from the boundary consistent with the unsteady Rayleigh problem. Finally, the ultimate test for this new method is to simulate the wall jet. The simulations produce a dipole instability along the wall as observed in water tank and wind tunnel experiments and predicted by linear stability analysis. Moreover, the wavelength and height of these simulations agree quantitatively with experimental observations.
Implicit calculations of transonic flows using monotone methods
NASA Astrophysics Data System (ADS)
Goorjian, P. M.; van Buskirk, R.
1981-01-01
Implicit approximate-factorization algorithms have been developed that use monotone methods for the calculation of steady and unsteady transonic flows governed by the small-disturbance-potential equation. These algorithms use the new Engquist-Osher switch in the type-dependent differencing in place of the standard Murman-Cole switch. The resulting algorithms are more stable; hence, calculations can be done more efficiently. For steady flows, the convergence rate is about 35% faster, and for unsteady flows the allowable time step is about 10 times larger. These improvements are achieved with no increase in computer storage and with only minor modifications in codes that use the Murman-Cole switch. Also an implicit algorithm has been developed for the steady full-potential equation in one-dimension, which uses monotone methods.
NASA Astrophysics Data System (ADS)
Jang, Jaeseong; Ahn, Chi Young; Jeon, Kiwan; Choi, Jung-il; Lee, Changhoon; Seo, Jin Keun
2015-03-01
A reconstruction method is proposed here to quantify the distribution of blood flow velocity fields inside the left ventricle from color Doppler echocardiography measurement. From 3D incompressible Navier- Stokes equation, a 2D incompressible Navier-Stokes equation with a mass source term is derived to utilize the measurable color flow ultrasound data in a plane along with the moving boundary condition. The proposed model reflects out-of-plane blood flows on the imaging plane through the mass source term. For demonstrating a feasibility of the proposed method, we have performed numerical simulations of the forward problem and numerical analysis of the reconstruction method. First, we construct a 3D moving LV region having a specific stroke volume. To obtain synthetic intra-ventricular flows, we performed a numerical simulation of the forward problem of Navier-Stokes equation inside the 3D moving LV, computed 3D intra-ventricular velocity fields as a solution of the forward problem, projected the 3D velocity fields on the imaging plane and took the inner product of the 2D velocity fields on the imaging plane and scanline directional velocity fields for synthetic scanline directional projected velocity at each position. The proposed method utilized the 2D synthetic projected velocity data for reconstructing LV blood flow. By computing the difference between synthetic flow and reconstructed flow fields, we obtained the averaged point-wise errors of 0.06 m/s and 0.02 m/s for u- and v-components, respectively.
Development of acoustic observation method for seafloor hydrothermal flows
NASA Astrophysics Data System (ADS)
Mochizuki, M.; Tamura, H.; Asada, A.; Kinoshita, M.; Tamaki, K.
2012-12-01
In October 2009, we conducted seafloor reconnaissance using a manned deep-sea submersible Shinkai6500 in Central Indian Ridge 18-20deg.S, where hydrothermal plume signatures were previously perceived. Acoustic video camera "DIDSON" was equipped on the top of Shinkai6500 in order to get acoustic video images of hydrothermal plumes. The acoustic video images of the hydrothermal plumes had been captured in three of seven dives. We could identify shadings inside the acoustic video images of the hydrothermal plumes. Silhouettes of the hydrothermal plumes varied from second to second, and the shadings inside them also varied. These variations corresponded to internal structures and flows of the plumes. DIDSON (Dual-Frequency IDentification SONar) is acoustic lens-based sonar. It has sufficiently high resolution and rapid refresh rate that it can substitute for optical system in turbid or dark water where optical systems fail. Ins. of Industrial Science, University of Tokyo has understood DIDSON's superior performance and tried to develop a new observation method based on DIDSON for hydrothermal discharging from seafloor vent. We expected DIDSON to reveal whole image of hydrothermal plume as well as detail inside the plume. The proposed method to observe and measure hydrothermal flow is the one to utilize a sheet-like acoustic beam. Scanning with concentrated acoustic beam gives distances to the edges of the hydrothermal flows. And then, the shapes of the flows can be identified even in low and zero visibility conditions. Tank experiment was conducted. The purposes of this experiment were to make an attempt at proposed method to delineate underwater hydrothermal flows and to understand relationships among acoustic video image, flow rate and water temperature. Water was heated in the hot tub and pumped to the water tank through the silicon tube. We observed water flows discharging from the tip of the tube with DIDSON. Flow rate had been controlled and temperatures of the
McGrail, Bernard P.; Martin, Paul F.; Lindenmeier, Clark W.
1999-01-01
The present invention is a method and apparatus for measuring coupled flow, transport and reaction processes under liquid unsaturated flow conditions. The method and apparatus of the present invention permit distinguishing individual precipitation events and their effect on dissolution behavior isolated to the specific event. The present invention is especially useful for dynamically measuring hydraulic parameters when a chemical reaction occurs between a particulate material and either liquid or gas (e.g. air) or both, causing precipitation that changes the pore structure of the test material.
New Methods for Sensitivity Analysis in Chaotic, Turbulent Fluid Flows
NASA Astrophysics Data System (ADS)
Blonigan, Patrick; Wang, Qiqi
2012-11-01
Computational methods for sensitivity analysis are invaluable tools for fluid mechanics research and engineering design. These methods are used in many applications, including aerodynamic shape optimization and adaptive grid refinement. However, traditional sensitivity analysis methods break down when applied to long-time averaged quantities in chaotic fluid flowfields, such as those obtained using high-fidelity turbulence simulations. Also, a number of dynamical properties of chaotic fluid flows, most notably the ``Butterfly Effect,'' make the formulation of new sensitivity analysis methods difficult. This talk will outline two chaotic sensitivity analysis methods. The first method, the Fokker-Planck adjoint method, forms a probability density function on the strange attractor associated with the system and uses its adjoint to find gradients. The second method, the Least Squares Sensitivity method, finds some ``shadow trajectory'' in phase space for which perturbations do not grow exponentially. This method is formulated as a quadratic programing problem with linear constraints. This talk is concluded with demonstrations of these new methods on some example problems, including the Lorenz attractor and flow around an airfoil at a high angle of attack.
Validation of an Impedance Education Method in Flow
NASA Technical Reports Server (NTRS)
Watson, Willie R.; Jones, Michael G.; Parrott, Tony L.
2004-01-01
This paper reports results of a research effort to validate a method for educing the normal incidence impedance of a locally reacting liner, located in a grazing incidence, nonprogressive acoustic wave environment with flow. The results presented in this paper test the ability of the method to reproduce the measured normal incidence impedance of a solid steel plate and two soft test liners in a uniform flow. The test liners are known to be locally react- ing and exhibit no measurable amplitude-dependent impedance nonlinearities or flow effects. Baseline impedance spectra for these liners were therefore established from measurements in a conventional normal incidence impedance tube. A key feature of the method is the expansion of the unknown impedance function as a piecewise continuous polynomial with undetermined coefficients. Stewart's adaptation of the Davidon-Fletcher-Powell optimization algorithm is used to educe the normal incidence impedance at each Mach number by optimizing an objective function. The method is shown to reproduce the measured normal incidence impedance spectrum for each of the test liners, thus validating its usefulness for determining the normal incidence impedance of test liners for a broad range of source frequencies and flow Mach numbers. Nomenclature
EPA flow reference method testing and analysis: Findings report. Appendices
1999-06-01
In the summer of 1997, the US Environmental Protection Agency (EPA) conducted a series of week-long field tests at three electric utility sites to evaluate potential improvements to Method 2, EPA`s test method for measuring flue gas volumetric flow in stacks. The findings from that study are presented in document EPA/430-R-99-009a (NTIS Order Number PB99-150286). This document contains 10 appendices for that report.
Combined PDF/SPH method for compressible turbulent flows
NASA Astrophysics Data System (ADS)
Welton, Walter Christian
A particle method which applies the probability density function (PDF) method to compressible turbulent flows is presented. Solution of the PDF equation is achieved using a Lagrangian/Monte Carlo approach which combines techniques borrowed from the field of smoothed particle hydrodynamics (SPH). This combination gives the method a unique ability to extract mean quantities, including the mean pressure gradient, directly from the particles using a grid-free approach. Two algorithms which greatly reduce the computational work for SPH in 1D and 2D have been developed to implement the method; for a simulation with N particles the computational work scales purely as {cal O}(N). The particle method has also been combined with a variance-reduction technique which can significantly reduce statistical error in first and second moments of selected mean flow quantities. When used with a second-order accurate predictor/corrector scheme, the resulting particle method provides a feasible way to obtain accurate PDF solutions to compressible turbulent flow problems. Results are presented for a variety of quasi-1D and 2D flows to demonstrate the method's robustness. These include solutions to both statistically stationary and nonstationary problems, and use both periodic and characteristic-based inflow/outflow boundary conditions. A 2D plane wake simulation also includes comparisons with experimental data and shows good agreement in spite of the simple turbulence model used. Comprehensive studies of numerical errors have also been performed, including a convergence study of the method. Detailed results are presented which confirm the expected behavior of each error.
Methods of Visually Determining the Air Flow Around Airplanes
NASA Technical Reports Server (NTRS)
Gough, Melvin N; Johnson, Ernest
1932-01-01
This report describes methods used by the National Advisory Committee for Aeronautics to study visually the air flow around airplanes. The use of streamers, oil and exhaust gas streaks, lampblack and kerosene, powdered materials, and kerosene smoke is briefly described. The generation and distribution of smoke from candles and from titanium tetrachloride are described in greater detail because they appear most advantageous for general application. Examples are included showing results of the various methods.
A Multi-domain Spectral Method for Supersonic Reactive Flows
NASA Technical Reports Server (NTRS)
Don, Wai-Sun; Gottlieb, David; Jung, Jae-Hun; Bushnell, Dennis M. (Technical Monitor)
2002-01-01
This paper has a dual purpose: it presents a multidomain Chebyshev method for the solution of the two-dimensional reactive compressible Navier-Stokes equations, and it reports the results of the application of this code to the numerical simulations of high Mach number reactive flows in recessed cavity. The computational method utilizes newly derived interface boundary conditions as well as an adaptive filtering technique to stabilize the computations. The results of the simulations are relevant to recessed cavity flameholders.
Simple numerical method for predicting steady compressible flows
NASA Technical Reports Server (NTRS)
Vonlavante, Ernst; Nelson, N. Duane
1986-01-01
A numerical method for solving the isenthalpic form of the governing equations for compressible viscous and inviscid flows was developed. The method was based on the concept of flux vector splitting in its implicit form. The method was tested on several demanding inviscid and viscous configurations. Two different forms of the implicit operator were investigated. The time marching to steady state was accelerated by the implementation of the multigrid procedure. Its various forms very effectively increased the rate of convergence of the present scheme. High quality steady state results were obtained in most of the test cases; these required only short computational times due to the relative efficiency of the basic method.
Stochastic Collocation Method for Three-dimensional Groundwater Flow
NASA Astrophysics Data System (ADS)
Shi, L.; Zhang, D.
2008-12-01
The stochastic collocation method (SCM) has recently gained extensive attention in several disciplines. The numerical implementation of SCM only requires repetitive runs of an existing deterministic solver or code as in the Monte Carlo simulation. But it is generally much more efficient than the Monte Carlo method. In this paper, the stochastic collocation method is used to efficiently qualify uncertainty of three-dimensional groundwater flow. We introduce the basic principles of common collocation methods, i.e., the tensor product collocation method (TPCM), Smolyak collocation method (SmCM), Stround-2 collocation method (StCM), and probability collocation method (PCM). Their accuracy, computational cost, and limitation are discussed. Illustrative examples reveal that the seamless combination of collocation techniques and existing simulators makes the new framework possible to efficiently handle complex stochastic problems.
Design method for the flow field and drag of bodies of revolution in incompressible flow
Wolfe, W.P.; Oberkampf, W.L.
1982-01-01
A design method has been developed for determining the flow field, pressure distribution, boundary layer separation point, and drag of bodies of revolution at zero angle of attack in incompressible flow. The approach taken is the classical coupling of potential and boundary solutions to obtain the flow field about the body. The potential solution is obtained by modeling the body with an axial distribution of source/sink elements whose strengths vary linearly along their length. The laminar and turbulent boundary layer solutions are obtained from conventional solutions of the momentum integral equation. An approximate method is used to estimate the boundary layer transition point on the body. An empirical base pressure correlation is used to determine the base drag. Body surface pressure distributions and drag predictions are compared with experimental measurements.
Traffic Flow Management Using Aggregate Flow Models and the Development of Disaggregation Methods
NASA Technical Reports Server (NTRS)
Sun, Dengfeng; Sridhar, Banavar; Grabbe, Shon
2010-01-01
A linear time-varying aggregate traffic flow model can be used to develop Traffic Flow Management (tfm) strategies based on optimization algorithms. However, there are no methods available in the literature to translate these aggregate solutions into actions involving individual aircraft. This paper describes and implements a computationally efficient disaggregation algorithm, which converts an aggregate (flow-based) solution to a flight-specific control action. Numerical results generated by the optimization method and the disaggregation algorithm are presented and illustrated by applying them to generate TFM schedules for a typical day in the U.S. National Airspace System. The results show that the disaggregation algorithm generates control actions for individual flights while keeping the air traffic behavior very close to the optimal solution.
A Three-Dimensional Vortex Sheet Method for Multiphase Flows
NASA Astrophysics Data System (ADS)
Stock, Mark; Dahm, Werner; Tryggvason, Gretar
2002-11-01
Previous work on a three-dimensional vortex-in-cell method is extended to include baroclinic vorticity generation in flows with large density ratios. A vortex sheet discretization is used both to maintain the boundary between different fluids or fluid phases, and to provide for a divergence-free vorticity field at all times. Automatic insertion and deletion of triangular elements allow the vortex sheet to maintain its connectivity and resolution during the simulation, despite extensive stretching of the material surface. The VIC grid provides regularization, and the simulation is inviscid at resolved scales. Computational results for flows with weak and strong density variations are presented.
A multilevel adaptive projection method for unsteady incompressible flow
NASA Technical Reports Server (NTRS)
Howell, Louis H.
1993-01-01
There are two main requirements for practical simulation of unsteady flow at high Reynolds number: the algorithm must accurately propagate discontinuous flow fields without excessive artificial viscosity, and it must have some adaptive capability to concentrate computational effort where it is most needed. We satisfy the first of these requirements with a second-order Godunov method similar to those used for high-speed flows with shocks, and the second with a grid-based refinement scheme which avoids some of the drawbacks associated with unstructured meshes. These two features of our algorithm place certain constraints on the projection method used to enforce incompressibility. Velocities are cell-based, leading to a Laplacian stencil for the projection which decouples adjacent grid points. We discuss features of the multigrid and multilevel iteration schemes required for solution of the resulting decoupled problem. Variable-density flows require use of a modified projection operator--we have found a multigrid method for this modified projection that successfully handles density jumps of thousands to one. Numerical results are shown for the 2D adaptive and 3D variable-density algorithms.
[Numerical methods for multi-fluid flows]. Final progress report
Pozrikidis, C.
1998-07-21
The central objective of this research has been to develop efficient numerical methods for computing multi-fluid flows with large interfacial deformations, and apply these methods to study the rheology of suspensions of deformable particles with viscous and non-Newtonian interfacial behavior. The mathematical formulation employs boundary-integral, immersed-boundary, and related numerical methods. Particles of interest include liquid drops with constant surface tension and capsules whose interfaces exhibit viscoelastic and incompressible characteristics. In one family of problems, the author has considered the shear-driven and pressure-driven flow of a suspension of two-dimensional liquid drops with ordered and random structure. In a second series of investigations, the author carried out dynamic simulations of two-dimensional, unbounded, doubly-periodic shear flows with random structure. Another family of problems addresses the deformation of three-dimensional capsules whose interfaces exhibit isotropic surface tension, viscous, elastic, or incompressible behavior, in simple shear flow. The numerical results extend previous asymptotic theories for small deformations and illuminate the mechanism of membrane rupture.
Modeling the flow in diffuse interface methods of solidification
NASA Astrophysics Data System (ADS)
Subhedar, A.; Steinbach, I.; Varnik, F.
2015-08-01
Fluid dynamical equations in the presence of a diffuse solid-liquid interface are investigated via a volume averaging approach. The resulting equations exhibit the same structure as the standard Navier-Stokes equation for a Newtonian fluid with a constant viscosity, the effect of the solid phase fraction appearing in the drag force only. This considerably simplifies the use of the lattice Boltzmann method as a fluid dynamics solver in solidification simulations. Galilean invariance is also satisfied within this approach. Further, we investigate deviations between the diffuse and sharp interface flow profiles via both quasiexact numerical integration and lattice Boltzmann simulations. It emerges from these studies that the freedom in choosing the solid-liquid coupling parameter h provides a flexible way of optimizing the diffuse interface-flow simulations. Once h is adapted for a given spatial resolution, the simulated flow profiles reach an accuracy comparable to quasiexact numerical simulations.
Modeling the flow in diffuse interface methods of solidification.
Subhedar, A; Steinbach, I; Varnik, F
2015-08-01
Fluid dynamical equations in the presence of a diffuse solid-liquid interface are investigated via a volume averaging approach. The resulting equations exhibit the same structure as the standard Navier-Stokes equation for a Newtonian fluid with a constant viscosity, the effect of the solid phase fraction appearing in the drag force only. This considerably simplifies the use of the lattice Boltzmann method as a fluid dynamics solver in solidification simulations. Galilean invariance is also satisfied within this approach. Further, we investigate deviations between the diffuse and sharp interface flow profiles via both quasiexact numerical integration and lattice Boltzmann simulations. It emerges from these studies that the freedom in choosing the solid-liquid coupling parameter h provides a flexible way of optimizing the diffuse interface-flow simulations. Once h is adapted for a given spatial resolution, the simulated flow profiles reach an accuracy comparable to quasiexact numerical simulations. PMID:26382542
Preconditioning methods for ideal and multiphase fluid flows
NASA Astrophysics Data System (ADS)
Gupta, Ashish
The objective of this study is to develop a preconditioning method for ideal and multiphase multispecies compressible fluid flow solver using homogeneous equilibrium mixture model. The mathematical model for fluid flow going through phase change uses density and temperature in the formulation, where the density represents the multiphase mixture density. The change of phase of the fluid is then explicitly determined using the equation of state of the fluid, which only requires temperature and mixture density. The method developed is based on a finite-volume framework in which the numerical fluxes are computed using Roe's approximate Riemann solver and the modified Harten, Lax and Van-leer scheme (HLLC). All speed Roe and HLLC flux based schemes have been developed either by using preconditioning or by directly modifying dissipation to reduce the effect of acoustic speed in its numerical dissipation when Mach number decreases. Preconditioning proposed by Briley, Taylor and Whitfield, Eriksson and Turkel are studied in this research, where as low dissipation schemes proposed by Rieper and Thornber, Mosedale, Drikakis, Youngs and Williams are also considered. Various preconditioners are evaluated in terms of development, performance, accuracy and limitations in simulations at various Mach numbers. A generalized preconditioner is derived which possesses well conditioned eigensystem for multiphase multispecies flow simulations. Validation and verification of the solution procedure are carried out on several small model problems with comparison to experimental, theoretical, and other numerical results. Preconditioning methods are evaluated using three basic geometries; 1) bump in a channel 2) flow over a NACA0012 airfoil and 3) flow over a cylinder, which are then compared with theoretical and numerical results. Multiphase capabilities of the solver are evaluated in cryogenic and non-cryogenic conditions. For cryogenic conditions the solver is evaluated by predicting
The ABC's of Financing Church and Synagogue Libraries. Acquiring Funds, Budgeting, Cash Accounting.
ERIC Educational Resources Information Center
Hannaford, Claudia
The ABCs of financing church and synagogue libraries are presented in this guide as Acquiring Funds, Budgeting, and Cash Accounting. Acquiring funds and the basic means needed to start a library are described, including resources such as books, shelves, office supplies, and financial resources; ideas and methods are presented for soliciting both…
Review of Upscaling Methods for Describing Unsaturated Flow
BD Wood
2000-09-26
The representation of small-scale features can be a challenge when attempting to model unsaturated flow in large domains. Upscaling methods offer the possibility of reducing the amount of resolution required to adequately simulate such a problem. In this report, the various upscaling techniques that are discussed in the literature are reviewed. The following upscaling methods have been identified from the literature: (1) stochastic methods, (2) renormalization methods, and (3) volume averaging and homogenization methods; in addition, a final technique, full resolution numerical modeling, is also discussed. Each of these techniques has its advantages and disadvantages. The trade-off is a reduction in accuracy in favor of a method that is easier to employ. For practical applications, the most reasonable approach appears to be one in which any of the upscaling methods identified above maybe suitable for upscaling in regions where the variations in the parameter fields are small. For regions where the subsurface structure is more complex, only the homogenization and volume averaging methods are probably suitable. With the continual increases in computational capacity, fill-resolution numerical modeling may in many instances provide a tractable means of solving the flow problem in unsaturated systems.
Pseudo-compressibility methods for the incompressible flow equations
NASA Technical Reports Server (NTRS)
Turkel, Eli; Arnone, A.
1993-01-01
Preconditioning methods to accelerate convergence to a steady state for the incompressible fluid dynamics equations are considered. The analysis relies on the inviscid equations. The preconditioning consists of a matrix multiplying the time derivatives. Thus the steady state of the preconditioned system is the same as the steady state of the original system. The method is compared to other types of pseudo-compressibility. For finite difference methods preconditioning can change and improve the steady state solutions. An application to viscous flow around a cascade with a non-periodic mesh is presented.
Wing analysis using a transonic potential flow computational method
NASA Technical Reports Server (NTRS)
Henne, P. A.; Hicks, R. M.
1978-01-01
The ability of the method to compute wing transonic performance was determined by comparing computed results with both experimental data and results computed by other theoretical procedures. Both pressure distributions and aerodynamic forces were evaluated. Comparisons indicated that the method is a significant improvement in transonic wing analysis capability. In particular, the computational method generally calculated the correct development of three-dimensional pressure distributions from subcritical to transonic conditions. Complicated, multiple shocked flows observed experimentally were reproduced computationally. The ability to identify the effects of design modifications was demonstrated both in terms of pressure distributions and shock drag characteristics.
Federal Register 2010, 2011, 2012, 2013, 2014
2012-07-19
... Creek Generation, LLC--Cash Creek Generation Station; Henderson County, KY AGENCY: Environmental... Generation, LLC for its Cash Creek Generation Station (Cash Creek) located near Owensboro in Henderson...
The new performance calculation method of fouled axial flow compressor.
Yang, Huadong; Xu, Hong
2014-01-01
Fouling is the most important performance degradation factor, so it is necessary to accurately predict the effect of fouling on engine performance. In the previous research, it is very difficult to accurately model the fouled axial flow compressor. This paper develops a new performance calculation method of fouled multistage axial flow compressor based on experiment result and operating data. For multistage compressor, the whole compressor is decomposed into two sections. The first section includes the first 50% stages which reflect the fouling level, and the second section includes the last 50% stages which are viewed as the clean stage because of less deposits. In this model, the performance of the first section is obtained by combining scaling law method and linear progression model with traditional stage stacking method; simultaneously ambient conditions and engine configurations are considered. On the other hand, the performance of the second section is calculated by averaged infinitesimal stage method which is based on Reynolds' law of similarity. Finally, the model is successfully applied to predict the 8-stage axial flow compressor and 16-stage LM2500-30 compressor. The change of thermodynamic parameters such as pressure ratio, efficiency with the operating time, and stage number is analyzed in detail. PMID:25197717
State-of-the-art methods for multiphase flow pipelines
Crowley, C.J.; Barry, J.J.; Rothe, P.H.
1989-08-01
This report is the culmination of work on Design Methods for Multiphase Flow in Gas Pipelines'' sponsored by the Pipeline Research Committee of the American Gas Association on projects PR 172--609 and PR 172--904. Results from a series of projects to obtain pipeline data in the field, collect operating pipeline data, perform key laboratory experiments at prototypical conditions (large pipe size and high gas density), and to develop and recommend design methods over the past several years have been synthesized to create this report. Technical supervision of these projects has been provided by the Two-Phase Flow Supervisory Committee. This report concisely documents the state of the art in two-phase flow methods, in a manner suitable for use by analysts who want to develop computerized methods to perform the multiphase calculations. This document updates a previous report prepared approximately four years ago (Crowley and Rothe, 1986). Detailed background discussion of the development and selection of the multiphase models is presented in Volume 3 of that reference.
The New Performance Calculation Method of Fouled Axial Flow Compressor
Xu, Hong
2014-01-01
Fouling is the most important performance degradation factor, so it is necessary to accurately predict the effect of fouling on engine performance. In the previous research, it is very difficult to accurately model the fouled axial flow compressor. This paper develops a new performance calculation method of fouled multistage axial flow compressor based on experiment result and operating data. For multistage compressor, the whole compressor is decomposed into two sections. The first section includes the first 50% stages which reflect the fouling level, and the second section includes the last 50% stages which are viewed as the clean stage because of less deposits. In this model, the performance of the first section is obtained by combining scaling law method and linear progression model with traditional stage stacking method; simultaneously ambient conditions and engine configurations are considered. On the other hand, the performance of the second section is calculated by averaged infinitesimal stage method which is based on Reynolds' law of similarity. Finally, the model is successfully applied to predict the 8-stage axial flow compressor and 16-stage LM2500-30 compressor. The change of thermodynamic parameters such as pressure ratio, efficiency with the operating time, and stage number is analyzed in detail. PMID:25197717
A level-set method for interfacial flows with surfactant
NASA Astrophysics Data System (ADS)
Xu, Jian-Jun; Li, Zhilin; Lowengrub, John; Zhao, Hongkai
2006-03-01
A level-set method for the simulation of fluid interfaces with insoluble surfactant is presented in two-dimensions. The method can be straightforwardly extended to three-dimensions and to soluble surfactants. The method couples a semi-implicit discretization for solving the surfactant transport equation recently developed by Xu and Zhao [J. Xu, H. Zhao. An Eulerian formulation for solving partial differential equations along a moving interface, J. Sci. Comput. 19 (2003) 573-594] with the immersed interface method originally developed by LeVeque and Li and [R. LeVeque, Z. Li. The immersed interface method for elliptic equations with discontinuous coefficients and singular sources, SIAM J. Numer. Anal. 31 (1994) 1019-1044] for solving the fluid flow equations and the Laplace-Young boundary conditions across the interfaces. Novel techniques are developed to accurately conserve component mass and surfactant mass during the evolution. Convergence of the method is demonstrated numerically. The method is applied to study the effects of surfactant on single drops, drop-drop interactions and interactions among multiple drops in Stokes flow under a steady applied shear. Due to Marangoni forces and to non-uniform Capillary forces, the presence of surfactant results in larger drop deformations and more complex drop-drop interactions compared to the analogous cases for clean drops. The effects of surfactant are found to be most significant in flows with multiple drops. To our knowledge, this is the first time that the level-set method has been used to simulate fluid interfaces with surfactant.
Cash on Demand: A Framework for Managing a Cash Liquidity Position.
ERIC Educational Resources Information Center
Augustine, John H.
1995-01-01
A well-run college or university will seek to accumulate and maintain an appropriate cash reserve or liquidity position. A rigorous analytic process for estimating the size and cost of a liquidity position, based on judgments about the institution's operating risks and opportunities, is outlined. (MSE)
Unstructured Mesh Methods for the Simulation of Hypersonic Flows
NASA Technical Reports Server (NTRS)
Peraire, Jaime; Bibb, K. L. (Technical Monitor)
2001-01-01
This report describes the research work undertaken at the Massachusetts Institute of Technology. The aim of this research is to identify effective algorithms and methodologies for the efficient and routine solution of hypersonic viscous flows about re-entry vehicles. For over ten years we have received support from NASA to develop unstructured mesh methods for Computational Fluid Dynamics. As a result of this effort a methodology based on the use, of unstructured adapted meshes of tetrahedra and finite volume flow solvers has been developed. A number of gridding algorithms flow solvers, and adaptive strategies have been proposed. The most successful algorithms developed from the basis of the unstructured mesh system FELISA. The FELISA system has been extensively for the analysis of transonic and hypersonic flows about complete vehicle configurations. The system is highly automatic and allows for the routine aerodynamic analysis of complex configurations starting from CAD data. The code has been parallelized and utilizes efficient solution algorithms. For hypersonic flows, a version of the, code which incorporates real gas effects, has been produced. One of the latest developments before the start of this grant was to extend the system to include viscous effects. This required the development of viscous generators, capable of generating the anisotropic grids required to represent boundary layers, and viscous flow solvers. In figures I and 2, we show some sample hypersonic viscous computations using the developed viscous generators and solvers. Although these initial results were encouraging, it became apparent that in order to develop a fully functional capability for viscous flows, several advances in gridding, solution accuracy, robustness and efficiency were required. As part of this research we have developed: 1) automatic meshing techniques and the corresponding computer codes have been delivered to NASA and implemented into the GridEx system, 2) a finite
Axial flow heat exchanger devices and methods for heat transfer using axial flow devices
Koplow, Jeffrey P.
2016-02-16
Systems and methods described herein are directed to rotary heat exchangers configured to transfer heat to a heat transfer medium flowing in substantially axial direction within the heat exchangers. Exemplary heat exchangers include a heat conducting structure which is configured to be in thermal contact with a thermal load or a thermal sink, and a heat transfer structure rotatably coupled to the heat conducting structure to form a gap region between the heat conducting structure and the heat transfer structure, the heat transfer structure being configured to rotate during operation of the device. In example devices heat may be transferred across the gap region from a heated axial flow of the heat transfer medium to a cool stationary heat conducting structure, or from a heated stationary conducting structure to a cool axial flow of the heat transfer medium.
Flow structures of Jupiter's Great Red Spot extracted by using optical flow method
NASA Astrophysics Data System (ADS)
Liu, Tianshu; Wang, Bo; Choi, David S.
2012-09-01
The flow structures of Jupiter's Great Red Spot (GRS) are studied based on a high-resolution velocity field extracted from the Galileo 1996 cloud images of the GRS by using the physics-based optical flow method. The mean transverse velocity profile across the anti-cyclonic near-elliptical collar of the GRS is obtained. The flow structures in the relatively quiescent inner region enclosed by the high-speed collar are revealed at a coarse-grained level. The cyclonic source node in the inner region is identified that is directly associated with the observed cyclonic rotation near the center of the GRS, and its significance in the maintenance of the GRS is explored by using a topological constraint.
Computational flow development for unsteady viscous flows: Foundation of the numerical method
NASA Technical Reports Server (NTRS)
Bratanow, T.; Spehert, T.
1978-01-01
A procedure is presented for effective consideration of viscous effects in computational development of high Reynolds number flows. The procedure is based on the interpretation of the Navier-Stokes equations as vorticity transport equations. The physics of the flow was represented in a form suitable for numerical analysis. Lighthill's concept for flow development for computational purposes was adapted. The vorticity transport equations were cast in a form convenient for computation. A statement for these equations was written using the method of weighted residuals and applying the Galerkin criterion. An integral representation of the induced velocity was applied on the basis of the Biot-Savart law. Distribution of new vorticity, produced at wing surfaces over small computational time intervals, was assumed to be confined to a thin region around the wing surfaces.
Multiple light scattering methods for multiphase flow diagnostics
NASA Astrophysics Data System (ADS)
Estevadeordal, Jordi
2015-11-01
Multiphase flows of gases and liquids containing droplets, bubbles, or particulates present light scattering imaging challenges due to the interference from each phase, such as secondary reflections, extinctions, absorptions, and refractions. These factors often prevent the unambiguous detection of each phase and also produce undesired beam steering. The effects can be especially complex in presence of dense phases, multispecies flows, and high pressure environments. This investigation reports new methods for overcoming these effects for quantitative measurements of velocity, density, and temperature fields. The methods are based on light scattering techniques combining Mie and filtered Rayleigh scattering and light extinction analyses and measurements. The optical layout is designed to perform multiple property measurements with improved signal from each phase via laser spectral and polarization characterization, etalon decontamination, and use of multiple wavelengths and imaging detectors.
Embedded function methods for compressible high speed turbulent flow
NASA Technical Reports Server (NTRS)
Walker, J. D. A.
1994-01-01
This is the final report on the work performed on the grant 'Embedded Function Methods for Compressible High Speed Turbulent Flow' carried out at Lehigh University during the contract period from September, 1987, to October of 1991. Work has continued at Lehigh on this project on an unfunded basis to the present. The original proposed work had two separate thrusts which were associated with developing embedded function methods in order to obviate the need to expend computational resources on turbulent wall layers in Navier Stokes and boundary-layer calculations. Previous work on the incompressible problem had indicated that this could be done successfully for two-dimensional and three-dimensional incompressible flows. The central objective here was to extend the basic approach to the high speed compressible problem.
Silver and gold enhancement methods for lateral flow immunoassays.
Rodríguez, Myriam Oliveira; Covián, Lucía Blanco; García, Agustín Costa; Blanco-López, Maria Carmen
2016-02-01
Sensitivity is the main concern at the development of rapid test by lateral flow immunoassays. On the other hand, low limits of detection are often required at medical diagnostics and other field of analysis. To overcome this drawback, several enhancement protocols have been described. In this paper, we have selected different silver enhancement methods and one dual gold conjugation, and we critically compared the amplification produced when applied to a gold-nanoparticle based lateral flow immunoassay for the detection of prostate specific antigen (PSA). The highest amplification was obtained by using an immersion method based on a solution of silver nitrate and hydroquinone/citrate buffer in proportion 1:1. Under these conditions, the system is capable of detecting PSA within 20 min at levels as low as 0.1 ng/mL, with a 3-fold sensitivity improvement. PMID:26653449
Research on stochastic power-flow study methods. Final report
Heydt, G. T.
1981-01-01
A general algorithm to determine the effects of uncertainty in bus load and generation on the output of conventional power flow analysis is presented. The use of statistical moments is presented and developed as a means for representing the stochastic process. Statistical moments are used to describe the uncertainties, and facilitate the calculations of single and multivarlate probability density functions of input and output variables. The transformation of the uncertainty through the power flow equations is made by the expansion of the node equations in a multivariate Taylor series about an expected operating point. The series is truncated after the second order terms. Since the power flow equations are nonlinear, the expected values of output quantities is in general not the solution to the conventional load flow problem using expected values of input quantities. The second order transformation offers a correction vector and allows the consideration of larger uncertainties which have caused significant error in the current linear transformation algorithms. Voltage controlled busses are included with consideration of upper and lower limits. The finite reactive power available at generation sites, and fixed ranges of transformer tap movement may have a significant effect on voltage and line power flow statistics. A method is given which considers limitation constraints in the evaluation of all output quantities. The bus voltages, line power flows, transformer taps, and generator reactive power requirements are described by their statistical moments. Their values are expressed in terms of the probability that they are above or below specified limits, and their expected values given that they do fall outside the limits. Thus the algorithm supplies information about severity of overload as well as probability of occurrence. An example is given for an eleven bus system, evaluating each quantity separately. The results are compared with Monte Carlo simulation.
Singularity computations. [finite element methods for elastoplastic flow
NASA Technical Reports Server (NTRS)
Swedlow, J. L.
1978-01-01
Direct descriptions of the structure of a singularity would describe the radial and angular distributions of the field quantities as explicitly as practicable along with some measure of the intensity of the singularity. This paper discusses such an approach based on recent development of numerical methods for elastoplastic flow. Attention is restricted to problems where one variable or set of variables is finite at the origin of the singularity but a second set is not.
Mathematical aspects of finite element methods for incompressible viscous flows
NASA Technical Reports Server (NTRS)
Gunzburger, M. D.
1986-01-01
Mathematical aspects of finite element methods are surveyed for incompressible viscous flows, concentrating on the steady primitive variable formulation. The discretization of a weak formulation of the Navier-Stokes equations are addressed, then the stability condition is considered, the satisfaction of which insures the stability of the approximation. Specific choices of finite element spaces for the velocity and pressure are then discussed. Finally, the connection between different weak formulations and a variety of boundary conditions is explored.
Method and apparatus for continuous flow injection extraction analysis
Hartenstein, Steven D.; Siemer, Darryl D.
1992-01-01
A method and apparatus for a continuous flow injection batch extraction aysis system is disclosed employing extraction of a component of a first liquid into a second liquid which is a solvent for a component of the first liquid, and is immiscible with the first liquid, and for separating the first liquid from the second liquid subsequent to extraction of the component of the first liquid.
Global convergence of inexact Newton methods for transonic flow
NASA Technical Reports Server (NTRS)
Young, David P.; Melvin, Robin G.; Bieterman, Michael B.; Johnson, Forrester T.; Samant, Satish S.
1990-01-01
In computational fluid dynamics, nonlinear differential equations are essential to represent important effects such as shock waves in transonic flow. Discretized versions of these nonlinear equations are solved using iterative methods. In this paper an inexact Newton method using the GMRES algorithm of Saad and Schultz is examined in the context of the full potential equation of aerodynamics. In this setting, reliable and efficient convergence of Newton methods is difficult to achieve. A poor initial solution guess often leads to divergence or very slow convergence. This paper examines several possible solutions to these problems, including a standard local damping strategy for Newton's method and two continuation methods, one of which utilizes interpolation from a coarse grid solution to obtain the initial guess on a finer grid. It is shown that the continuation methods can be used to augment the local damping strategy to achieve convergence for difficult transonic flow problems. These include simple wings with shock waves as well as problems involving engine power effects. These latter cases are modeled using the assumption that each exhaust plume is isentropic but has a different total pressure and/or temperature than the freestream.
Newton like: Minimal residual methods applied to transonic flow calculations
NASA Technical Reports Server (NTRS)
Wong, Y. S.
1984-01-01
A computational technique for the solution of the full potential equation is presented. The method consists of outer and inner iterations. The outer iterate is based on a Newton like algorithm, and a preconditioned Minimal Residual method is used to seek an approximate solution of the system of linear equations arising at each inner iterate. The present iterative scheme is formulated so that the uncertainties and difficulties associated with many iterative techniques, namely the requirements of acceleration parameters and the treatment of additional boundary conditions for the intermediate variables, are eliminated. Numerical experiments based on the new method for transonic potential flows around the NACA 0012 airfoil at different Mach numbers and different angles of attack are presented, and these results are compared with those obtained by the Approximate Factorization technique. Extention to three dimensional flow calculations and application in finite element methods for fluid dynamics problems by the present method are also discussed. The Inexact Newton like method produces a smoother reduction in the residual norm, and the number of supersonic points and circulations are rapidly established as the number of iterations is increased.
The Boundary Integral Equation Method for Porous Media Flow
NASA Astrophysics Data System (ADS)
Anderson, Mary P.
Just as groundwater hydrologists are breathing sighs of relief after the exertions of learning the finite element method, a new technique has reared its nodes—the boundary integral equation method (BIEM) or the boundary equation method (BEM), as it is sometimes called. As Liggett and Liu put it in the preface to The Boundary Integral Equation Method for Porous Media Flow, “Lately, the Boundary Integral Equation Method (BIEM) has emerged as a contender in the computation Derby.” In fact, in July 1984, the 6th International Conference on Boundary Element Methods in Engineering will be held aboard the Queen Elizabeth II, en route from Southampton to New York. These conferences are sponsored by the Department of Civil Engineering at Southampton College (UK), whose members are proponents of BIEM. The conferences have featured papers on applications of BIEM to all aspects of engineering, including flow through porous media. Published proceedings are available, as are textbooks on application of BIEM to engineering problems. There is even a 10-minute film on the subject.
Immersed boundary method for the MHD flows of liquid metals
NASA Astrophysics Data System (ADS)
Grigoriadis, D. G. E.; Kassinos, S. C.; Votyakov, E. V.
2009-02-01
Wall-bounded magnetohydrodynamic (MHD hereafter) flows are of great theoretical and practical interest. Even for laminar cases, MHD simulations are associated with very high computational cost due to the resolution requirements for the Hartmann and side layers developing in the presence of solid obstacles. In the presence of turbulence, these difficulties are further compounded. Thus, MHD simulations in complex geometries are currently a challenge. The immersed boundary (IB hereafter) method is a reliable numerical tool for efficient hydrodynamic field simulations in arbitrarily geometries, but it has not yet been extended for MHD simulations. The present study forms the first attempt to apply the IB methodology for the computation of both the hydrodynamic and MHD fields. A consistent numerical methodology is presented that is appropriate for efficient 3D MHD simulations in geometrically complicated domains using cartesian flow solvers. For that purpose, a projection scheme for the electric current density is presented, based on an electric potential correction algorithm. A suitable forcing scheme for electric density currents in the vicinity of non-conducting immersed surfaces is also proposed. The proposed methodology has been first extensively tested for Hartmann layers in fully-developed and developing channel and duct flows at Hartmann numbers Ha=500-2000. In order to demonstrate the potential of the method, the three-dimensional MHD flow around a circular cylinder at Reynolds number Re=200 is also presented. The effects of grid resolution and variable arrangement on the simulation accuracy and consistency were examined. When compared with existing numerical or analytic solutions, excellent agreement was found for all the cases considered. The proposed projection and forcing schemes for current densities were found capable of satisfying the charge conservation law in the presence of immersed non-conducting boundaries. Finally, we show how the proposed
A multigrid nonoscillatory method for computing high speed flows
NASA Technical Reports Server (NTRS)
Li, C. P.; Shieh, T. H.
1993-01-01
A multigrid method using different smoothers has been developed to solve the Euler equations discretized by a nonoscillatory scheme up to fourth order accuracy. The best smoothing property is provided by a five-stage Runge-Kutta technique with optimized coefficients, yet the most efficient smoother is a backward Euler technique in factored and diagonalized form. The singlegrid solution for a hypersonic, viscous conic flow is in excellent agreement with the solution obtained by the third order MUSCL and Roe's method. Mach 8 inviscid flow computations for a complete entry probe have shown that the accuracy is at least as good as the symmetric TVD scheme of Yee and Harten. The implicit multigrid method is four times more efficient than the explicit multigrid technique and 3.5 times faster than the single-grid implicit technique. For a Mach 8.7 inviscid flow over a blunt delta wing at 30 deg incidence, the CPU reduction factor from the three-level multigrid computation is 2.2 on a grid of 37 x 41 x 73 nodes.
Adaptive Discrete Equation Method for injection of stochastic cavitating flows
NASA Astrophysics Data System (ADS)
Geraci, Gianluca; Rodio, Maria Giovanna; Iaccarino, Gianluca; Abgrall, Remi; Congedo, Pietro
2014-11-01
This work aims at the improvement of the prediction and of the control of biofuel injection for combustion. In fact, common injector should be optimized according to the specific physical/chemical properties of biofuels. In order to attain this scope, an optimized model for reproducing the injection for several biofuel blends will be considered. The originality of this approach is twofold, i) the use of cavitating two-phase compressible models, known as Baer & Nunziato, in order to reproduce the injection, and ii) the design of a global scheme for directly taking into account experimental measurements uncertainties in the simulation. In particular, stochastic intrusive methods display a high efficiency when dealing with discontinuities in unsteady compressible flows. We have recently formulated a new scheme for simulating stochastic multiphase flows relying on the Discrete Equation Method (DEM) for describing multiphase effects. The set-up of the intrusive stochastic method for multiphase unsteady compressible flows in quasi 1D configuration will be presented. The target test-case is a multiphase unsteady nozzle for injection of biofuels, described by complex thermodynamics models, for which experimental data and associated uncertainties are available.
Selective flow path alpha particle detector and method of use
Orr, Christopher Henry; Luff, Craig Janson; Dockray, Thomas; Macarthur, Duncan Whittemore
2002-01-01
A method and apparatus for monitoring alpha contamination are provided in which ions generated in the air surrounding the item, by the passage of alpha particles, are moved to a distant detector location. The parts of the item from which ions are withdrawn can be controlled by restricting the air flow over different portions of the apparatus. In this way, detection of internal and external surfaces separately, for instance, can be provided. The apparatus and method are particularly suited for use in undertaking alpha contamination measurements during the commissioning operations.
Per-channel basis normalization methods for flow cytometry data
Hahne, Florian; Khodabakhshi, Alireza Hadj; Bashashati, Ali; Wong, Chao-Jen; Gascoyne, Randy D.; Weng, Andrew P.; Seifert-Margolis, Vicky; Bourcier, Katarzyna; Asare, Adam; Lumley, Thomas; Gentleman, Robert; Brinkman, Ryan R.
2013-01-01
Between-sample variation in high throughput flow cytometry data poses a significant challenge for analysis of large scale data sets, such as those derived from multi-center clinical trials. It is often hard to match biologically relevant cell populations across samples due to technical variation in sample acquisition and instrumentation differences. Thus normalization of data is a critical step prior to analysis, particularly in large-scale data sets from clinical trials, where group specific differences may be subtle and patient-to-patient variation common. We have developed two normalization methods that remove technical between-sample variation by aligning prominent features (landmarks) in the raw data on a per-channel basis. These algorithms were tested on two independent flow cytometry data sets by comparing manually gated data, either individually for each sample or using static gating templates, before and after normalization. Our results show a marked improvement in the overlap between manual and static gating when the data are normalized, thereby facilitating the use of automated analyses on large flow cytometry data sets. Such automated analyses are essential for high throughput flow cytometry. PMID:19899135
A multilayer method of fundamental solutions for Stokes flow problems
NASA Astrophysics Data System (ADS)
Boselli, F.; Obrist, D.; Kleiser, L.
2012-07-01
The method of fundamental solutions (MFS) is a meshless method for the solution of boundary value problems and has recently been proposed as a simple and efficient method for the solution of Stokes flow problems. The MFS approximates the solution by an expansion of fundamental solutions whose singularities are located outside the flow domain. Typically, the source points (i.e. the singularities of the fundamental solutions) are confined to a smooth source layer embracing the flow domain. This monolayer implementation of the MFS (monolayer MFS) depends strongly on the location of the user-defined source points: On the one hand, increasing the distance of the source points from the boundary tends to increase the convergence rate. On the other hand, this may limit the achievable accuracy. This often results in an unfavorable compromise between the convergence rate and the achievable accuracy of the MFS. The idea behind the present work is that a multilayer implementation of the MFS (multilayer MFS) can improve the robustness of the MFS by efficiently resolving different scales of the solution by source layers at different distances from the boundary. We propose a block greedy-QR algorithm (BGQRa) which exploits this property in a multilevel fashion. The proposed multilayer MFS is much more robust than the monolayer MFS and can compute Stokes flows on general two- and three-dimensional domains. It converges rapidly and yields high levels of accuracy by combining the properties of distant and close source points. The block algorithm alleviates the overhead of multiple source layers and allows the multilayer MFS to outperform the monolayer MFS.
Numerical Method for Darcy Flow Derived Using Discrete Exterior Calculus
NASA Astrophysics Data System (ADS)
Hirani, A. N.; Nakshatrala, K. B.; Chaudhry, J. H.
2015-05-01
We derive a numerical method for Darcy flow, and also for Poisson's equation in mixed (first order) form, based on discrete exterior calculus (DEC). Exterior calculus is a generalization of vector calculus to smooth manifolds and DEC is one of its discretizations on simplicial complexes such as triangle and tetrahedral meshes. DEC is a coordinate invariant discretization, in that it does not depend on the embedding of the simplices or the whole mesh. We start by rewriting the governing equations of Darcy flow using the language of exterior calculus. This yields a formulation in terms of flux differential form and pressure. The numerical method is then derived by using the framework provided by DEC for discretizing differential forms and operators that act on forms. We also develop a discretization for a spatially dependent Hodge star that varies with the permeability of the medium. This also allows us to address discontinuous permeability. The matrix representation for our discrete non-homogeneous Hodge star is diagonal, with positive diagonal entries. The resulting linear system of equations for flux and pressure are saddle type, with a diagonal matrix as the top left block. The performance of the proposed numerical method is illustrated on many standard test problems. These include patch tests in two and three dimensions, comparison with analytically known solutions in two dimensions, layered medium with alternating permeability values, and a test with a change in permeability along the flow direction. We also show numerical evidence of convergence of the flux and the pressure. A convergence experiment is included for Darcy flow on a surface. A short introduction to the relevant parts of smooth and discrete exterior calculus is included in this article. We also include a discussion of the boundary condition in terms of exterior calculus.
NASA Technical Reports Server (NTRS)
Mcfarland, E. R.
1981-01-01
A solution method was developed for calculating compressible inviscid flow through a linear cascade of arbitrary blade shapes. The method uses advanced surface singularity formulations which were adapted from those in current external flow analyses. The resulting solution technique provides a fast flexible calculation for flows through turbomachinery blade rows. The solution method and some examples of the method's capabilities are presented.
Multi-rate flowing Wellbore electric conductivity logging method
Tsang, Chin-Fu; Doughty, Christine
2003-04-22
The flowing wellbore electric conductivity logging method involves the replacement of wellbore water by de-ionized or constant-salinity water, followed by constant pumping with rate Q, during which a series of fluid electric conductivity logs are taken. The logs can be analyzed to identify depth locations of inflow, and evaluate the transmissivity and electric conductivity (salinity) of the fluid at each inflow point. The present paper proposes the use of the method with two or more pumping rates. In particular it is recommended that the method be applied three times with pumping rates Q, Q /2, and 2Q. Then a combined analysis of the multi-rate data allows an efficient means of determining transmissivity and salinity values of all inflow points along a well with a confidence measure, as well as their inherent or far-field pressure heads. The method is illustrated by a practical example.
General flow field analysis methods for helicopter rotor aeroacoustics
NASA Technical Reports Server (NTRS)
Quackenbush, Todd R.; Lam, C. Gordon; Bliss, Donald B.
1991-01-01
Previous work in the analysis of rotor flow fields for aeroacoustic applications involved the preliminary development of an efficient and accurate Lagrangian simulation of the unsteady vorticity field in the vicinity of helicopter main rotor that could analyze a limited class of rotor/wake interactions. The capabilities of this analysis have subsequently been considerably enhanced to allow it to serve as the foundation for a general analysis of the rotor/wake interaction noise. This paper presents the details of these enhancements, which focus on the expansion of the reconstruction approach developed previously to handle arbitrary vortex wake interactions within three-dimensional regions located near or within the rotor disk. Also, the development of nearfield velocity corrections appropriate for the analysis of such interactions is described, as is a preliminary study of methods for using the new high-resolution flow field analysis for noise predictions. The results show that by employing this novel flow field reconstruction technique it is possible to employ full-span free wake analyses with temporal and spatial resolution suitable for acoustic applications while reducing the computation time required by one to two orders of magnitude relative to traditional methods.
Validation of a numerical method for unsteady flow calculations
Giles, M.; Haimes, R. . Dept. of Aeronautics and Astronautics)
1993-01-01
This paper describes and validates a numerical method for the calculation of unsteady inviscid and viscous flows. A companion paper compares experimental measurements of unsteady heat transfer on a transonic rotor with the corresponding computational results. The mathematical model is the Reynolds-averaged unsteady Navier-Stokes equations for a compressible ideal gas. Quasi-three-dimensionality is included through the use of a variable streamtube thickness. The numerical algorithm is unusual in two respects: (a) For reasons of efficiency and flexibility, it uses a hybrid Navier-Stokes/Euler method, and (b) to allow for the computation of stator/rotor combinations with arbitrary pitch ratio, a novel space-time coordinate transformation is used. Several test cases are presented to validate the performance of the computer program, UNSFLO. These include: (a) unsteady, inviscid flat plate cascade flows (b) steady and unsteady, viscous flat plate cascade flows, (c) steady turbine heat transfer and loss prediction. In the first two sets of cases comparisons are made with theory, and in the third the comparison is with experimental data.
A power flow method for evaluating vibration from underground railways
NASA Astrophysics Data System (ADS)
Hussein, M. F. M.; Hunt, H. E. M.
2006-06-01
One of the major sources of ground-borne vibration is the running of trains in underground railway tunnels. Vibration is generated at the wheel-rail interface, from where it propagates through the tunnel and surrounding soil into nearby buildings. An understanding of the dynamic interfaces between track, tunnel and soil is essential before engineering solutions to the vibration problem can be found. A new method has been developed to evaluate the effectiveness of vibration countermeasures. The method is based on calculating the mean power flow from the tunnel, paying attention to that part of the power which radiates upwards to places where buildings' foundations are expected to be found. The mean power is calculated for an infinite train moving through the tunnel with a constant velocity. An elegant mathematical expression for the mean power flow is derived, which can be used with any underground-tunnel model. To evaluate the effect of vibration countermeasures and track properties on power flow, a comprehensive three-dimensional analytical model is used. It consists of Euler-Bernoulli beams to account for the rails and the track slab. These are coupled in the wavenumber-frequency domain to a thin shell representing the tunnel embedded within an infinite continuum, with a cylindrical cavity representing the surrounding soil.
36 CFR 254.12 - Value equalization; cash equalization waiver.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 36 Parks, Forests, and Public Property 2 2012-07-01 2012-07-01 false Value equalization; cash... AGRICULTURE LANDOWNERSHIP ADJUSTMENTS Land Exchanges § 254.12 Value equalization; cash equalization waiver. (a... to as compensation for costs under § 254.7 of this subpart may not exceed 25 percent of the value...
36 CFR 254.12 - Value equalization; cash equalization waiver.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 36 Parks, Forests, and Public Property 2 2013-07-01 2013-07-01 false Value equalization; cash... AGRICULTURE LANDOWNERSHIP ADJUSTMENTS Land Exchanges § 254.12 Value equalization; cash equalization waiver. (a... to as compensation for costs under § 254.7 of this subpart may not exceed 25 percent of the value...
43 CFR 2201.6 - Value equalization; cash equalization waiver.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 43 Public Lands: Interior 2 2012-10-01 2012-10-01 false Value equalization; cash equalization... PROCEDURES Exchanges-Specific Requirements § 2201.6 Value equalization; cash equalization waiver. (a) To... as compensation for costs under § 2201.1-3 of this part may not exceed 25 percent of the value of...
43 CFR 2201.6 - Value equalization; cash equalization waiver.
Code of Federal Regulations, 2013 CFR
2013-10-01
... 43 Public Lands: Interior 2 2013-10-01 2013-10-01 false Value equalization; cash equalization... PROCEDURES Exchanges-Specific Requirements § 2201.6 Value equalization; cash equalization waiver. (a) To... as compensation for costs under § 2201.1-3 of this part may not exceed 25 percent of the value of...
36 CFR 254.12 - Value equalization; cash equalization waiver.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 36 Parks, Forests, and Public Property 2 2010-07-01 2010-07-01 false Value equalization; cash... AGRICULTURE LANDOWNERSHIP ADJUSTMENTS Land Exchanges § 254.12 Value equalization; cash equalization waiver. (a... to as compensation for costs under § 254.7 of this subpart may not exceed 25 percent of the value...
43 CFR 2201.6 - Value equalization; cash equalization waiver.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 43 Public Lands: Interior 2 2011-10-01 2011-10-01 false Value equalization; cash equalization... PROCEDURES Exchanges-Specific Requirements § 2201.6 Value equalization; cash equalization waiver. (a) To equalize the agreed upon values of the Federal and non-Federal lands involved in an exchange, either...
36 CFR 254.12 - Value equalization; cash equalization waiver.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 36 Parks, Forests, and Public Property 2 2011-07-01 2011-07-01 false Value equalization; cash... AGRICULTURE LANDOWNERSHIP ADJUSTMENTS Land Exchanges § 254.12 Value equalization; cash equalization waiver. (a) To equalize the agreed upon values of the Federal and non-Federal lands involved in an...
Subsistence Agriculture versus Cash Cropping: The Social Repercussions.
ERIC Educational Resources Information Center
Rennie, Sandra Joy
1991-01-01
The introduction of cash cropping in the Solomon Islands and Tonga has had negative effects on women, leading to deterioration in their status, decreased leisure time, fewer opportunities to earn cash, increased birth rate (to help with the increased workload), and more sharply defined sex roles. (SV)
Code of Federal Regulations, 2010 CFR
2010-01-01
... 7 Agriculture 4 2010-01-01 2010-01-01 false SSI cash-out. 273.20 Section 273.20 Agriculture... FOOD STAMP AND FOOD DISTRIBUTION PROGRAM CERTIFICATION OF ELIGIBLE HOUSEHOLDS § 273.20 SSI cash-out. (a) Ineligibility. No individual who receives supplemental security income (SSI) benefits and/or State...
Code of Federal Regulations, 2014 CFR
2014-01-01
... 7 Agriculture 4 2014-01-01 2014-01-01 false SSI cash-out. 273.20 Section 273.20 Agriculture Regulations of the Department of Agriculture (Continued) FOOD AND NUTRITION SERVICE, DEPARTMENT OF AGRICULTURE FOOD STAMP AND FOOD DISTRIBUTION PROGRAM CERTIFICATION OF ELIGIBLE HOUSEHOLDS Program Alternatives § 273.20 SSI cash-out. (a) Ineligibility....
18 CFR 260.400 - Cash management programs.
Code of Federal Regulations, 2011 CFR
2011-04-01
... 18 Conservation of Power and Water Resources 1 2011-04-01 2011-04-01 false Cash management... Cash management programs. Natural gas companies subject to the provisions of the Commission's Uniform... management programs must file these agreements with the Commission. The documentation establishing the...
18 CFR 260.400 - Cash management programs.
Code of Federal Regulations, 2012 CFR
2012-04-01
... 18 Conservation of Power and Water Resources 1 2012-04-01 2012-04-01 false Cash management... Cash management programs. Natural gas companies subject to the provisions of the Commission's Uniform... management programs must file these agreements with the Commission. The documentation establishing the...
17 CFR 256.136 - Temporary cash investments.
Code of Federal Regulations, 2011 CFR
2011-04-01
... 17 Commodity and Securities Exchanges 3 2011-04-01 2011-04-01 false Temporary cash investments... UTILITY HOLDING COMPANY ACT OF 1935 3. Current and Accrued Assets § 256.136 Temporary cash investments. This account shall include the cost of investments, such as demand and time loans, bankers'...
17 CFR 256.136 - Temporary cash investments.
Code of Federal Regulations, 2010 CFR
2010-04-01
... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Temporary cash investments... UTILITY HOLDING COMPANY ACT OF 1935 3. Current and Accrued Assets § 256.136 Temporary cash investments. This account shall include the cost of investments, such as demand and time loans, bankers'...
25 CFR 140.24 - Cash payments only to Indians.
Code of Federal Regulations, 2010 CFR
2010-04-01
... 25 Indians 1 2010-04-01 2010-04-01 false Cash payments only to Indians. 140.24 Section 140.24 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR FINANCIAL ACTIVITIES LICENSED INDIAN TRADERS § 140.24 Cash payments only to Indians. Traders must not pay Indians in tokens, tickets, store...
18 CFR 260.400 - Cash management programs.
Code of Federal Regulations, 2010 CFR
2010-04-01
... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Cash management... Cash management programs. Natural gas companies subject to the provisions of the Commission's Uniform... management programs must file these agreements with the Commission. The documentation establishing the...
Improved vortex methods for three-dimensional flows
NASA Technical Reports Server (NTRS)
Winckelmans, G.; Leonard, A.
1989-01-01
Robust numerical methods are developed for three-dimensional incompressible vortical flows, using Lagrangian vortex elements. A successful scheme must be able to handle regions of intense vortex stretching and vortex reconnection with reasonable accuracy (without diverging). Here, consideration is given to vortex particles, also commonly called vortons or vortex sticks. The following issues are discussed: (1) use of delta-function elements and weak solutions of the vorticity equation; (2) use of smoothed elements and the choice of the smoothing function; (3) representation of viscous effects and the redistribution of element strength; and (4) conservation laws (are they satisfied?). The various proposed schemes have been tested on flows involving a strong interaction between two vortex rings.
Deformation-phase measurement by optical flow method
NASA Astrophysics Data System (ADS)
Zhao, Ran; Sun, Ping
2016-07-01
A novel algorithm which extract the out-of-plane component of deformation-phase from two continuous fringe patterns is proposed. The whole-field out-of-plane component of deformation-phase map is obtained by the estimations of the optical flow velocity field between two images and the local frequency of the original image. In this paper, the proposed algorithm is introduced and applied to simulated and experimental interferograms. Simulation and experimental results show that the new method can demodulate the out-of-plane component of deformation-phase from the visible optical flow velocity field without the operation of phase unwrapping. Further, the proposed algorithm provides a new approach for whole-field deformation-phase measurement and dynamic deformation measurement.
Method and apparatus for detecting laminar flow separation and reattachment
NASA Technical Reports Server (NTRS)
Stack, John P. (Inventor); Mangalam, Sivaramakrishnan M. (Inventor)
1989-01-01
The invention is a method and apparatus for detecting laminar flow separation and flow reattachment of a fluid stream by simultaneously sensing and comparing a plurality of output signals, each representing the dynamic shear stress at one of an equal number of sensors spaced along a straight line on the surface of an airfoil or the like that extends parallel to the fluid stream. The output signals are concurrently compared to detect the sensors across which a reversal in phase of said output signal occurs, said detected sensors being in the region of laminar separation or reattachment. The novelty in this invention is the discovery and use of the phase reversal phenomena to detect laminar separation and attachment of a fluid stream from any surface such as an airfoil supported therein.
A nearly real-time UAV video flow mosaic method
NASA Astrophysics Data System (ADS)
Zheng, H.; Jiang, C.; Sun, M.; Li, X. D.; Xiang, R.; Liu, Lei
2014-12-01
In order to solve the problem of low accuracy and high computation cost of current video mosaic methods, and also to acquire large field of view images by the unmanned aerial vehicles (UAV), which have high accuracy and high resolution, this paper propose a method for near real-time mosaic of video flow, so that we can provide essential reference data for the earthquake relief, as well as post-disaster reconstruction and recovery, in time. In this method, we obtain the flight area scope in the route planning process, and calculate the sizes of each frame with sensor sizes and altitudes. Given an overlap degree, time intervals are calculated, and key frames are extracted. After that, feature points are detected in each frame, and they are matched using Hamming distance. The RANSAC algorithm is then applied to remove error matching and calculate parameters of the transformation model. In one-strip case, the newly extracted frame is taken as the reference image in the first half, while after the middle frame is extracted, it is the reference one until the end. Experimental results show that our method can reduce the cascading error, and improve the accuracy and quality of the mosaic images, near real-time mosaic of aerial video flow is feasible.
A diffusive information preservation method for small Knudsen number flows
NASA Astrophysics Data System (ADS)
Fei, Fei; Fan, Jing
2013-06-01
The direct simulation Monte Carlo (DSMC) method is a powerful particle-based method for modeling gas flows. It works well for relatively large Knudsen (Kn) numbers, typically larger than 0.01, but quickly becomes computationally intensive as Kn decreases due to its time step and cell size limitations. An alternative approach was proposed to relax or remove these limitations, based on replacing pairwise collisions with a stochastic model corresponding to the Fokker-Planck equation [J. Comput. Phys., 229, 1077 (2010); J. Fluid Mech., 680, 574 (2011)]. Similar to the DSMC method, the downside of that approach suffers from computationally statistical noise. To solve the problem, a diffusion-based information preservation (D-IP) method has been developed. The main idea is to track the motion of a simulated molecule from the diffusive standpoint, and obtain the flow velocity and temperature through sampling and averaging the IP quantities. To validate the idea and the corresponding model, several benchmark problems with Kn ˜ 10-3-10-4 have been investigated. It is shown that the IP calculations are not only accurate, but also efficient because they make possible using a time step and cell size over an order of magnitude larger than the mean collision time and mean free path, respectively.
Logically rectangular mixed methods for Darcy flow on general geometry
Arbogast, T.; Keenan, P.T.; Wheeler, M.F.; Yotov, I.
1995-12-31
The authors consider an expanded mixed finite element formulation (cell centered finite difference) for Darcy flow with a tensor absolute permeability. The reservoir can be geometrically general with internal features, but the computational domain is rectangular. The method is defined on a curvilinear grid that need not be orthogonal, obtained by mapping the rectangular, computational grid. The original flow problem becomes a similar problem with a modified permeability on the computational grid. Quadrature rules turn the mixed method into a cell-centered finite difference method with a 9 point stencil in 2-D and 19 in 3-D. As shown by theory and experiment, if the modified permeability on the computational domain is smooth, then the convergence rate is optimal and both pressure and velocity are superconvergent at certain points. If not, Lagrange multiplier pressures can be introduced on boundaries of elements so that optimal convergence is retained. This modification presents only small changes in the solution process; in fact, the same parallel domain decomposition algorithms can be applied with little or no change to the code if the modified permeability is smooth over the subdomains. This Lagrange multiplier procedure can be used to extend the difference scheme to multi-block domains, and to give a coupling with unstructured grids. In all cases, the mixed formulation is locally conservative. Computational results illustrate the advantage and convergence of this method.
A diffusive information preservation method for small Knudsen number flows
Fei, Fei; Fan, Jing
2013-06-15
The direct simulation Monte Carlo (DSMC) method is a powerful particle-based method for modeling gas flows. It works well for relatively large Knudsen (Kn) numbers, typically larger than 0.01, but quickly becomes computationally intensive as Kn decreases due to its time step and cell size limitations. An alternative approach was proposed to relax or remove these limitations, based on replacing pairwise collisions with a stochastic model corresponding to the Fokker–Planck equation [J. Comput. Phys., 229, 1077 (2010); J. Fluid Mech., 680, 574 (2011)]. Similar to the DSMC method, the downside of that approach suffers from computationally statistical noise. To solve the problem, a diffusion-based information preservation (D-IP) method has been developed. The main idea is to track the motion of a simulated molecule from the diffusive standpoint, and obtain the flow velocity and temperature through sampling and averaging the IP quantities. To validate the idea and the corresponding model, several benchmark problems with Kn ∼ 10{sup −3}–10{sup −4} have been investigated. It is shown that the IP calculations are not only accurate, but also efficient because they make possible using a time step and cell size over an order of magnitude larger than the mean collision time and mean free path, respectively.
Domain decomposition methods for the parallel computation of reacting flows
NASA Astrophysics Data System (ADS)
Keyes, David E.
1989-05-01
Domain decomposition is a natural route to parallel computing for partial differential equation solvers. In this procedure, subdomains of which the original domain of definition is comprised are assigned to independent processors at the price of periodic coordination between processors to compute global parameters and maintain the requisite degree of continuity of the solution at the subdomain interfaces. In the domain-decomposed solution of steady multidimensional systems of PDEs by finite difference methods using a pseudo-transient version of Newton iteration, the only portion of the computation which generally stands in the way of efficient parallelization is the solution of the large, sparse linear systems arising at each Newton step. For some Jacobian matrices drawn from an actual two-dimensional reacting flow problem, we make comparisons between relaxation-based linear solvers and also preconditioned iterative methods of Conjugate Gradient and Chebyshev type, focusing attention on both iteration count and global inner product count. The generalized minimum residual method with block-ILU preconditioning is judged the best serial method among those considered, and parallel numerical experiments on the Encore Multimax demostrate for it approximately 10-fold speedup on 16 processsors. The three special features of reacting flow models in relation to these linear systems are: the possibly large number of degrees of freedom per gridpoint, the dominance of dense intra-point source-term coupling over inter-point convective-diffusive coupling throughout significant portions of the flow-field and strong nonlinearities which restrict the time step to small values (independent of linear algebraic considerations) throughout significant portions of the iteration history. Though these features are exploited to advantage herein, many aspects of the paper are applicable to the modeling of general convective-diffusive systems.
An Engineering Aerodynamic Heating Method for Hypersonic Flow
NASA Technical Reports Server (NTRS)
Riley, Christopher J.; DeJarnette, Fred R.
1992-01-01
A capability to calculate surface heating rates has been incorporated in an approximate three-dimensional inviscid technique. Surface streamlines are calculated from the inviscid solution, and the axisymmetric analog is then used along with a set of approximate convective-heating equations to compute the surface heat transfer. The method is applied to blunted axisymmetric and three-dimensional ellipsoidal cones at angle of attack for the laminar flow of a perfect gas. The method is also applicable to turbulent and equilibrium-air conditions. The present technique predicts surface heating rates that compare favorably with experimental (ground-test and flight) data and numerical solutions of the Navier-Stokes (NS) and viscous shock-layer (VSL) equations. The new technique represents a significant improvement over current engineering aerothermal methods with only a modest increase in computational effort.
Massively parallel simulations of multiphase flows using Lattice Boltzmann methods
NASA Astrophysics Data System (ADS)
Ahrenholz, Benjamin
2010-03-01
In the last two decades the lattice Boltzmann method (LBM) has matured as an alternative and efficient numerical scheme for the simulation of fluid flows and transport problems. Unlike conventional numerical schemes based on discretizations of macroscopic continuum equations, the LBM is based on microscopic models and mesoscopic kinetic equations. The fundamental idea of the LBM is to construct simplified kinetic models that incorporate the essential physics of microscopic or mesoscopic processes so that the macroscopic averaged properties obey the desired macroscopic equations. Especially applications involving interfacial dynamics, complex and/or changing boundaries and complicated constitutive relationships which can be derived from a microscopic picture are suitable for the LBM. In this talk a modified and optimized version of a Gunstensen color model is presented to describe the dynamics of the fluid/fluid interface where the flow field is based on a multi-relaxation-time model. Based on that modeling approach validation studies of contact line motion are shown. Due to the fact that the LB method generally needs only nearest neighbor information, the algorithm is an ideal candidate for parallelization. Hence, it is possible to perform efficient simulations in complex geometries at a large scale by massively parallel computations. Here, the results of drainage and imbibition (Degree of Freedom > 2E11) in natural porous media gained from microtomography methods are presented. Those fully resolved pore scale simulations are essential for a better understanding of the physical processes in porous media and therefore important for the determination of constitutive relationships.
Biochemical oxygen demand measurement by mediator method in flow system.
Liu, Ling; Bai, Lu; Yu, Dengbin; Zhai, Junfeng; Dong, Shaojun
2015-06-01
Using mediator as electron acceptor for biochemical oxygen demand (BOD) measurement was developed in the last decade (BODMed). However, until now, no BOD(Med) in a flow system has been reported. This work for the first time describes a flow system of BOD(Med) method (BOD(Med)-FS) by using potassium ferricyanide as mediator and carbon fiber felt as substrate material for microbial immobilization. The system can determine the BOD value within 30 min and possesses a wider analytical linear range for measuring glucose-glutamic acid (GGA) standard solution from 2 up to 200 mg L(-1) without the need of dilution. The analytical performance of the BOD(Med)-FS is comparable or better than that of the previously reported BOD(Med) method, especially its superior long-term stability up to 2 months under continuous operation. Moreover, the BOD(Med)-FS has same determination accuracy with the conventional BOD5 method by measuring real samples from a local wastewater treatment plant (WWTP). PMID:25863368
Testing the global flow reconstruction method on coupled chaotic oscillators
NASA Astrophysics Data System (ADS)
Plachy, Emese; Kolláth, Zoltán
2010-03-01
Irregular behaviour of pulsating variable stars may occur due to low dimensional chaos. To determine the quantitative properties of the dynamics in such systems, we apply a suitable time series analysis, the global flow reconstruction method. The robustness of the reconstruction can be tested through the resultant quantities, like Lyapunov dimension and Fourier frequencies. The latter is specially important as it is directly derivable from the observed light curves. We have performed tests using coupled Rossler oscillators to investigate the possible connection between those quantities. In this paper we present our test results.
A Flow SPR Immunosensor Based on a Sandwich Direct Method
Tomassetti, Mauro; Conta, Giorgia; Campanella, Luigi; Favero, Gabriele; Sanzò, Gabriella; Mazzei, Franco; Antiochia, Riccarda
2016-01-01
In this study, we report the development of an SPR (Surface Plasmon Resonance) immunosensor for the detection of ampicillin, operating under flow conditions. SPR sensors based on both direct (with the immobilization of the antibody) and competitive (with the immobilization of the antigen) methods did not allow the detection of ampicillin. Therefore, a sandwich-based sensor was developed which showed a good linear response towards ampicillin between 10−3 and 10−1 M, a measurement time of ≤20 min and a high selectivity both towards β-lactam antibiotics and antibiotics of different classes. PMID:27187486
A Flow SPR Immunosensor Based on a Sandwich Direct Method.
Tomassetti, Mauro; Conta, Giorgia; Campanella, Luigi; Favero, Gabriele; Sanzò, Gabriella; Mazzei, Franco; Antiochia, Riccarda
2016-01-01
In this study, we report the development of an SPR (Surface Plasmon Resonance) immunosensor for the detection of ampicillin, operating under flow conditions. SPR sensors based on both direct (with the immobilization of the antibody) and competitive (with the immobilization of the antigen) methods did not allow the detection of ampicillin. Therefore, a sandwich-based sensor was developed which showed a good linear response towards ampicillin between 10(-3) and 10(-1) M, a measurement time of ≤20 min and a high selectivity both towards β-lactam antibiotics and antibiotics of different classes. PMID:27187486
An analysis method for two-dimensional transonic viscous flow
NASA Technical Reports Server (NTRS)
Bavitz, P. C.
1975-01-01
A method for the approximate calculation of transonic flow over airfoils, including shock waves and viscous effects, is described. Numerical solutions are obtained by use of a computer program which is discussed in the appendix. The importance of including the boundary layer in the analysis is clearly demonstrated, as well as the need to improve on existing procedures near the trailing edge. Comparisons between calculations and experimental data are presented for both conventional and supercritical airfoils, emphasis being on the surface pressure distribution, and good agreement is indicated.
COMPREHENSIVE METHOD OF CHARACTERISTICS MODELS FOR FLOW SIMULATION.
Lai, Chintu
1988-01-01
The use of the specified time interval (STI) numerical schemes has been popular in applying the method of characteristics (MOC) to unsteady open-channel flow problems. Studies and analyses of several variants of the STI schemes have led to the derivation of a new scheme, referred to herein as the multimode scheme, which combines implicit, temporal reachback, spatial reachback, and classical schemes into one. Three numerical models have been developed to implement the implicit and multimode schemes. Numerical analyses, numerical experiments, and field applications that verify, support, and demonstrate the enhanced model capabilities are presented.
A boundary element method for steady incompressible thermoviscous flow
NASA Technical Reports Server (NTRS)
Dargush, G. F.; Banerjee, P. K.
1991-01-01
A boundary element formulation is presented for moderate Reynolds number, steady, incompressible, thermoviscous flows. The governing integral equations are written exclusively in terms of velocities and temperatures, thus eliminating the need for the computation of any gradients. Furthermore, with the introduction of reference velocities and temperatures, volume modeling can often be confined to only a small portion of the problem domain, typically near obstacles or walls. The numerical implementation includes higher order elements, adaptive integration and multiregion capability. Both the integral formulation and implementation are discussed in detail. Several examples illustrate the high level of accuracy that is obtainable with the current method.
Variational method for finding periodic orbits in a general flow.
Lan, Yueheng; Cvitanović, Predrag
2004-01-01
A variational principle is proposed and implemented for determining unstable periodic orbits of flows as well as unstable spatiotemporally periodic solutions of extended systems. An initial loop approximating a periodic solution is evolved in the space of loops toward a true periodic solution by a minimization of local errors along the loop. The "Newton descent" partial differential equation that governs this evolution is an infinitesimal step version of the damped Newton-Raphson iteration. The feasibility of the method is demonstrated by its application to the Hénon-Heiles system, the circular restricted three-body problem, and the Kuramoto-Sivashinsky system in a weakly turbulent regime. PMID:14995703
Improved numerical method for subchannel cross-flow calculations
Kaya, S.; Anghaie, S.
1986-01-01
COBRA-OSU is a fast running computer code for coupled kinetic and thermal-hydraulic analysis of nuclear reactor core subchannels, currently under development at Oregon State University. This code is a modified version of COBRA-IV with two major improved features. First, COBRA-OSU uses the Gaussian elimination method instead of Gauss-Seidel iteration for subchannel cross-flow calculation. Second, COBRA-OSU has an additional model for regionwise point reactor kinetics which includes all major feedback reactivity effects on calculation of the axial power profile during the course of a transient. This paper summarizes the improved numerical features of the COBRA-OSU code.
NASA Astrophysics Data System (ADS)
Dubinov, Alexander E.; Mytareva, Lyubov'A.
2010-08-01
The current knowledge of the physics of electromagnetic cloaking of material objects by the wave flow method is reviewed. Experiments demonstrating the feasibility of this cloaking method are described. Some aspects of calculating cloak profiles are examined, and achievements and unsolved problems in the theory of the interaction of electromagnetic waves with shells are considered. Prospects for developing the cloaking method for waves of other physical nature (acoustic and probability density waves) are discussed.
A digital physics method for two-phase flow
NASA Astrophysics Data System (ADS)
Freed, David M.
1997-10-01
Digital Physics refers to a fully discrete, microdynamieal system whose mean behavior recovers real continuum physics. The purpose of this project is to develop a Digital Physics method by which to model the flow of single-component fluids with a non-ideal-gas equation of state, such as liquids and two-phase mixtures. The new system, called the multiphase system, is built upon the framework of a previously developed Digital Physics system. This original Digital Physics system, the standard system, is used to simulate low Mach number flow of an ideal gas. Previously, substantial performance improvements (compared to CFD numerical solvers) have been achieved with the standard system for hydrodynamic simulations of ideal gas flows. Hence the underlying motivation of this work is the development of a more efficient simulation tool for detailed two phase flow investigation as compared to current numerical methods. Specifically, the multiphase system simulates the local instantaneous flow field including explicit representation of the interfaces. The multiphase system contains significant extensions of the standard system, particularly a non-local operation allowing microscopic interactions at a distance, loosely mimicking a real liquid, while preserving exact (global) conservation of mass, momentum, and energy. It retains the advantages of Digital Physics compared to other lattice gas methods for flow modeling, such as Galilean invariance, elimination of the dynamic pressure anomaly, and a meaningful energy transport equation. In the multiphase system the energy degree of freedom has been extended to allow a consistent empirical thermodynamics suitable for a system with liquid-vapor coexistence. Thus in addition to correct hydrodynamic transport, the multiphase system achieves appropriate equations of state for the liquid and vapor phases; the current implementation employs a van der Waals thermodynamical system. The multiphase system does not model heat transfer
The effects of national cash awards for science teaching on recipients and their peers
NASA Astrophysics Data System (ADS)
Weld, Jeffrey Donn
Cash teaching awards available to science teachers in the U.S. have goals to improve science teaching. This study assessed the effectiveness of five national cash award programs at identifying exemplars and inspiring better science teaching. Award winning secondary science teachers provided their perceptions of the effects of an award on their own teaching and on the profession as a whole. Randomly selected secondary science teachers across the U.S. reported their perceptions of the effects of the existence of awards on their own teaching and on the profession. Program directors for the five national cash awards were interviewed to determine the intentions and strategies of their award programs. The criteria that guide the selection of award winners were found to align with research-supported exemplar characteristics, but the methods used for identifying outstanding teachers were found to be inadequate for that purpose. Award winning science teachers perceive awards to result from, rather than to inspire, good teaching. Their motivation derives from student achievement and a job well done. The valued effects of winning an award are the recognition and increased respect that follow. Award winners perceive awards as difficult to win, minimally motivating, and frequently causing of dissension among peers. In most respects award winners perceive increased intrinsic rewards to accompany recognition through cash awards. Randomly selected U.S. science teachers who have not won cash awards perceive them as poor motivational incentives because too few awards exist, the basis for recognition is unclear, and the award itself is not a valued outcome. Most science teachers consider themselves good teachers and would apply for an award despite doubts that they would win. Direct comparisons reveal that winners and nonwinners have widely divergent opinions of awards. Winners of lesser cash amounts have the same perceptions of awards as winners of greater cash amounts. Effective
Visualization and Quantification of Fingering Flow Using Light Transmission Method
NASA Astrophysics Data System (ADS)
Rezanezhad, F.; Roth, K.
2007-12-01
With the aim of studying the physical process concerning the unstable fingering phenomena in two dimensions, experiments of vertical infiltration through layered sand were carried out in the laboratory using Hele-Shaw cells. We developed a light transmission method to measure the dynamics of water saturation within flow fingers in great detail with high spatial and temporal resolution. The method was calibrated using X-ray absorption. We improved the measured light transmission with correction for scattering effects through deconvolution with a point spread function which allows us to obtain quantitative high spatial resolution measurements. After fingers had fully developed, we added a dye tracer in order to distinguish mobile and immobile water fractions. Fully developed fingers consist of a tip, a core with mobile water, and a hull with immobile water. We analyzed the dynamics of water saturation within the finger tip, along the finger core behind the tip, and within the fringe of the fingers during radial growth. Our results confirm previous findings of saturation overshoot in the finger tips and revealed a saturation minimum behind the tip as a new feature. The finger development was characterized by a gradual increase in water content within the core of the finger behind this minimum and a gradual widening of the fingers to a quasi-stable state which evolves at time scales that are orders of magnitude longer than those of fingers' evolution. In this state, a sharp separation into a core with fast convective flow and a fringe with exceedingly slow flow was detected. All observed phenomena, with the exception of saturation overshoot, could be consistently explained based on the hysteretic behavior of the soil-water characteristic.
NASA Astrophysics Data System (ADS)
Crane, R. A.; Cuthbert, M. O.; Timms, W.
2015-09-01
We present an interrupted-flow centrifugation technique to characterise preferential flow in low permeability media. The method entails a minimum of three phases: centrifuge-induced flow, no flow and centrifuge-induced flow, which may be repeated several times in order to most effectively characterise multi-rate mass transfer behaviour. In addition, the method enables accurate simulation of relevant in situ total stress conditions during flow by selecting an appropriate centrifugal force. We demonstrate the utility of the technique for characterising the hydraulic properties of smectite-clay-dominated core samples. All core samples exhibited a non-Fickian tracer breakthrough (early tracer arrival), combined with a decrease in tracer concentration immediately after each period of interrupted flow. This is indicative of dual (or multi-)porosity behaviour, with solute migration predominately via advection during induced flow, and via molecular diffusion (between the preferential flow network(s) and the low hydraulic conductivity domain) during interrupted flow. Tracer breakthrough curves were simulated using a bespoke dual porosity model with excellent agreement between the data and model output (Nash-Sutcliffe model efficiency coefficient was > 0.97 for all samples). In combination, interrupted-flow centrifuge experiments and dual porosity transport modelling are shown to be a powerful method to characterise preferential flow in low permeability media.
NASA Astrophysics Data System (ADS)
Crane, R. A.; Cuthbert, M. O.; Timms, W.
2015-01-01
We present an interrupted-flow centrifugation technique to characterise preferential flow in low permeability media. The method entails a minimum of three phases: centrifuge induced flow, no flow and centrifuge induced flow, which may be repeated several times in order to most effectively characterise multi-rate mass transfer behaviour. In addition, the method enables accurate simulation of relevant in situ total stress conditions during flow by selecting an appropriate centrifugal force level. We demonstrate the utility of the technique for characterising the hydraulic properties of smectite clay dominated core samples. All samples exhibited a non-Fickian tracer breakthrough (early tracer arrival), combined with a decrease in tracer concentration immediately after each period of interrupted-flow. This is indicative of dual (or multi) porosity behaviour, with solute migration predominately via advection during induced flow, and via molecular diffusion (between the preferential flow network(s) and the low hydraulic conductivity domain) during interrupted-flow. Tracer breakthrough curves were simulated using a bespoke dual porosity model with excellent agreement between the data and model output (Nash-Sutcliffe model efficiency coefficient was >0.97 for all samples). In combination interrupted-flow centrifuge experiments and dual porosity transport modelling are shown to be a powerful method to characterise preferential flow in low permeability media.
A reconstruction method for gappy and noisy arterial flow data.
Yakhot, Alexander; Anor, Tomer; Karniadakis, George Em
2007-12-01
Proper orthogonal decomposition (POD), Kriging interpolation, and smoothing are applied to reconstruct gappy and noisy data of blood flow in a carotid artery. While we have applied these techniques to clinical data, in this paper in order to rigorously evaluate their effectiveness we rely on data obtained by computational fluid dynamics (CFD). Specifically, gappy data sets are generated by removing nodal values from high-resolution 3-D CFD data (at random or in a fixed area) while noisy data sets are formed by superimposing speckle noise on the CFD results. A combined POD-Kriging procedure is applied to planar data sets mimicking coarse resolution "ultrasound-like" blood flow images. A method for locating the vessel wall boundary and for calculating the wall shear stress (WSS) is also proposed. The results show good agreement with the original CFD data. The combined POD-Kriging method, enhanced by proper smoothing if needed, holds great potential in dealing effectively with gappy and noisy data reconstruction of in vivo velocity measurements based on color Doppler ultrasound (CDUS) imaging or magnetic resonance angiography (MRA). PMID:18092738
An Anelastic Allspeed Projection Method for GravitationallyStratified Flows
Gatti-Bono, Caroline; Colella, Phillip
2005-02-24
This paper looks at gravitationally-stratified atmospheric flows at low Mach and Froude numbers and proposes a new algorithm to solve the compressible Euler equations, in which the asymptotic limits are recovered numerically and the boundary conditions for block-structured local refinement methods are well-posed. The model is non-hydrostatic and the numerical algorithm uses a splitting to separate the fast acoustic dynamics from the slower anelastic dynamics. The acoustic waves are treated implicitly while the anelastic dynamics is treated semi-implicitly and an embedded-boundary method is used to represent mountain ranges. We present an example that verifies our asymptotic analysis and a set of results that compares very well with the classical gravity wave results presented by Durran.
Development of the caregivers attitude scale on home care of schizophrenics (CASHS)
Balasubramanian, N; Sathyanarayana Rao, T. S.; D’Sa, Juliana Linnette
2014-01-01
Background: Schizophrenia is a severe mental disorder that elicits feelings of strangeness and discomfort, which may create stigma and lead to the social exclusion of the mentally ill and of the people relating with them. In the past decade, there has been an increase in the number of research studies on attitudes toward mental disorders. Materials and Methods: An instrument was developed to assess the attitude of primary caregivers on home care of schizophrenics. This article describes the development of a Likert scale, the Caregivers Attitude Scale on Home Care of Schizophrenics CASHS, which is a 31-item self-reported instrument that quantifies three aspects of home care, that is, attitude towards patient, towards treatment, and towards social interaction. The steps involved in its development are the review of literature, development of items, content validation, translation and language validity, pretesting, and reliability. Results: After establishing the content validity, the CASHS was pretested with five subjects. To establish the reliability of the CASHS, 21 primary caregivers were recruited through purposive sampling technique. In order to measure the stability between scores obtained, a test-retest reliability was computed using Karl Pearson correlation coefficient and the r value was 0.78. The internal consistency was measured using Cronbach's alpha and item-total correlation and the r value was 0.789. The item discrimination analysis was also computed and the value was of above 0.35. These statistical measurements indicate that the CASHS was reliable. Conclusions: The CASHS is a valid and reliable tool that can be utilized for assessing the attitude of primary caregivers on home care of schizophrenics. PMID:24574561
Method and apparatus for controlling the flow rate of mercury in a flow system
Grossman, Mark W.; Speer, Richard
1991-01-01
A method for increasing the mercury flow rate to a photochemical mercury enrichment utilizing an entrainment system comprises the steps of passing a carrier gas over a pool of mercury maintained at a first temperature T1, wherein the carrier gas entrains mercury vapor; passing said mercury vapor entrained carrier gas to a second temperature zone T2 having temperature less than T1 to condense said entrained mercury vapor, thereby producing a saturated Hg condition in the carrier gas; and passing said saturated Hg carrier gas to said photochemical enrichment reactor.
Comparative analysis of whole blood lysis methods for flow cytometry.
Bossuyt, X; Marti, G E; Fleisher, T A
1997-06-15
We performed a parallel evaluation of six whole blood lysis methods comparing light scatter and quantitative fluorescence intensity based on quantitative flow cytometry, of selected lymphocyte subsets and CD34+ cells. Leukocytes prepared with FACS Lysing Solution (BDIS), Immunolyse (Coulter) and Optilyse B (Immunotech) consistently gave lower forward scatter values than those prepared with ACK (BioWhitaker), Ortho-mune (Ortho) and ImmunoPrep (Coulter). Debris, defined as CD45 negative events with the threshold off, accounted approximately 80% of all events with ACK and Ortho-mune. The other lysing methods consistently yielded less debris (approximately 50%) with Immunolyse generating only approximately 16% debris. Optilyse and FACS lyse consistently displayed the lowest percentage of lymphoid cells (CD45+/CD14-) in the three part differential. The percentage of CD3+, CD20+, CD5+, and CD16/CD56+ cells was consistent with all methods but CD4 and CD8 determinants showed inconsistent variation with ACK and Ortho-mune. In addition, the fluorescence intensity of CD14 PE and CD8 PE staining was markedly decreased on cells prepared with ImmunoPrep. Finally, the clearest separation of CD34+ cells was observed with ACK and Ortho-mune. Our data demonstrate that the method used for red cell lysis can have definite impact on immunophenotyping and selected methods appear to be more suitable for specific applications. PMID:9222098
A new general 1-D vadose zone flow solution method
NASA Astrophysics Data System (ADS)
Ogden, Fred L.; Lai, Wencong; Steinke, Robert C.; Zhu, Jianting; Talbot, Cary A.; Wilson, John L.
2015-06-01
We have developed an alternative to the one-dimensional partial differential equation (PDE) attributed to Richards (1931) that describes unsaturated porous media flow in homogeneous soil layers. Our solution is a set of three ordinary differential equations (ODEs) derived from unsaturated flux and mass conservation principles. We used a hodograph transformation, the Method of Lines, and a finite water-content discretization to produce ODEs that accurately simulate infiltration, falling slugs, and groundwater table dynamic effects on vadose zone fluxes. This formulation, which we refer to as "finite water-content", simulates sharp fronts and is guaranteed to conserve mass using a finite-volume solution. Our ODE solution method is explicitly integrable, does not require iterations and therefore has no convergence limits and is computationally efficient. The method accepts boundary fluxes including arbitrary precipitation, bare soil evaporation, and evapotranspiration. The method can simulate heterogeneous soils using layers. Results are presented in terms of fluxes and water content profiles. Comparing our method against analytical solutions, laboratory data, and the Hydrus-1D solver, we find that predictive performance of our finite water-content ODE method is comparable to or in some cases exceeds that of the solution of Richards' equation, with or without a shallow water table. The presented ODE method is transformative in that it offers accuracy comparable to the Richards (1931) PDE numerical solution, without the numerical complexity, in a form that is robust, continuous, and suitable for use in large watershed and land-atmosphere simulation models, including regional-scale models of coupled climate and hydrology.
Bluff Body Flow Simulation Using a Vortex Element Method
Anthony Leonard; Phillippe Chatelain; Michael Rebel
2004-09-30
Heavy ground vehicles, especially those involved in long-haul freight transportation, consume a significant part of our nation's energy supply. it is therefore of utmost importance to improve their efficiency, both to reduce emissions and to decrease reliance on imported oil. At highway speeds, more than half of the power consumed by a typical semi truck goes into overcoming aerodynamic drag, a fraction which increases with speed and crosswind. Thanks to better tools and increased awareness, recent years have seen substantial aerodynamic improvements by the truck industry, such as tractor/trailer height matching, radiator area reduction, and swept fairings. However, there remains substantial room for improvement as understanding of turbulent fluid dynamics grows. The group's research effort focused on vortex particle methods, a novel approach for computational fluid dynamics (CFD). Where common CFD methods solve or model the Navier-Stokes equations on a grid which stretches from the truck surface outward, vortex particle methods solve the vorticity equation on a Lagrangian basis of smooth particles and do not require a grid. They worked to advance the state of the art in vortex particle methods, improving their ability to handle the complicated, high Reynolds number flow around heavy vehicles. Specific challenges that they have addressed include finding strategies to accurate capture vorticity generation and resultant forces at the truck wall, handling the aerodynamics of spinning bodies such as tires, application of the method to the GTS model, computation time reduction through improved integration methods, a closest point transform for particle method in complex geometrics, and work on large eddy simulation (LES) turbulence modeling.
Domain decomposition methods for the parallel computation of reacting flows
NASA Technical Reports Server (NTRS)
Keyes, David E.
1988-01-01
Domain decomposition is a natural route to parallel computing for partial differential equation solvers. Subdomains of which the original domain of definition is comprised are assigned to independent processors at the price of periodic coordination between processors to compute global parameters and maintain the requisite degree of continuity of the solution at the subdomain interfaces. In the domain-decomposed solution of steady multidimensional systems of PDEs by finite difference methods using a pseudo-transient version of Newton iteration, the only portion of the computation which generally stands in the way of efficient parallelization is the solution of the large, sparse linear systems arising at each Newton step. For some Jacobian matrices drawn from an actual two-dimensional reacting flow problem, comparisons are made between relaxation-based linear solvers and also preconditioned iterative methods of Conjugate Gradient and Chebyshev type, focusing attention on both iteration count and global inner product count. The generalized minimum residual method with block-ILU preconditioning is judged the best serial method among those considered, and parallel numerical experiments on the Encore Multimax demonstrate for it approximately 10-fold speedup on 16 processors.
Numerical method of characteristics for one-dimensional blood flow
NASA Astrophysics Data System (ADS)
Acosta, Sebastian; Puelz, Charles; Rivière, Béatrice; Penny, Daniel J.; Rusin, Craig G.
2015-08-01
Mathematical modeling at the level of the full cardiovascular system requires the numerical approximation of solutions to a one-dimensional nonlinear hyperbolic system describing flow in a single vessel. This model is often simulated by computationally intensive methods like finite elements and discontinuous Galerkin, while some recent applications require more efficient approaches (e.g. for real-time clinical decision support, phenomena occurring over multiple cardiac cycles, iterative solutions to optimization/inverse problems, and uncertainty quantification). Further, the high speed of pressure waves in blood vessels greatly restricts the time step needed for stability in explicit schemes. We address both cost and stability by presenting an efficient and unconditionally stable method for approximating solutions to diagonal nonlinear hyperbolic systems. Theoretical analysis of the algorithm is given along with a comparison of our method to a discontinuous Galerkin implementation. Lastly, we demonstrate the utility of the proposed method by implementing it on small and large arterial networks of vessels whose elastic and geometrical parameters are physiologically relevant.
Fujimura, N.; Ohta, M.; Abdo, G.; Ylmaz, H.; Lovblad, K.-O; Rüfenacht, D.A.
2006-01-01
Summary Stent implants placed across the neck of cerebral aneurysms are capable of reducing aneurysmal flow when coils are not used for filling the aneurysms. It is important to evaluate the effects of flow reduction caused by stent implants used for the treatment of cerebral aneurysms. Subtracted vortex centers path line method (SVC method) is one of the image post processing methods employed for quantitative flow measurement. We developed a modified SVC method by employing Cinematic Angiography (25 frames/s) and digital video recording (30 frames/s) with a commercial digital camera. We successfully compared the flow effectiveness using a tubular silicon model with a sidewall aneurysm. The result suggests that our modified SVC method is useful for a comparative examination of the effect of aneurysmal flow reduction caused by stent implants. PMID:20569631
Finite volume methods for submarine debris flows and generated waves
NASA Astrophysics Data System (ADS)
Kim, Jihwan; Løvholt, Finn; Issler, Dieter
2016-04-01
Submarine landslides can impose great danger to the underwater structures and generate destructive tsunamis. Submarine debris flows often behave like visco-plastic materials, and the Herschel-Bulkley rheological model is known to be appropriate for describing the motion. In this work, we develop numerical schemes for the visco-plastic debris flows using finite volume methods in Eulerian coordinates with two horizontal dimensions. We provide parameter sensitivity analysis and demonstrate how common ad-hoc assumptions such as including a minimum shear layer depth influence the modeling of the landslide dynamics. Hydrodynamic resistance forces, hydroplaning, and remolding are all crucial terms for underwater landslides, and are hence added into the numerical formulation. The landslide deformation is coupled to the water column and simulated in the Clawpack framework. For the propagation of the tsunamis, the shallow water equations and the Boussinesq-type equations are employed to observe how important the wave dispersion is. Finally, two cases in central Norway, i.e. the subaerial quick clay landslide at Byneset in 2012, and the submerged tsunamigenic Statland landslide in 2014, are both presented for validation. The research leading to these results has received funding from the Research Council of Norway under grant number 231252 (Project TsunamiLand) and the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement 603839 (Project ASTARTE).
NASA Technical Reports Server (NTRS)
GELBART ABE; Bartnoff, Shepard
1947-01-01
A general method for studying the flow of a compressible fluid around a closed body was discussed in Part I of this report. Here, application is made to the specific case in which the linearized equation of state is used. For a given incompressible flow around a specific profile, a corresponding compressible flow is found. The flow at infinity remains unchanged. Detailed studies are made of the flow with circulation around a unit circle, and velocity distributions are found for a wide range of Mach number and angle of attack. Comparisons are made with other methods.
Provider automation. The secret to better cash flow.
Steenhuysen, J
1995-02-01
Morton Plant Hospital has a remarkable track record in applying automation in its business office. The provider cut its receivables in half while reducing patient complaints about billing. PMID:10143838
Valuing uncertain cash flows from investments that enhance energy efficiency.
Abadie, Luis M; Chamorro, José M; González-Eguino, Mikel
2013-02-15
There is a broad consensus that investments to enhance energy efficiency quickly pay for themselves in lower energy bills and spared emission allowances. However, investments that at first glance seem worthwhile usually are not undertaken. One of the plausible, non-excluding explanations is the numerous uncertainties that these investments face. This paper deals with the optimal time to invest in an energy efficiency enhancement at a facility already in place that consumes huge amounts of a fossil fuel (coal) and operates under carbon constraints. We follow the Real Options approach. Our model comprises three sources of uncertainty following different stochastic processes which allows for application in a broad range of settings. We assess the investment option by means of a three-dimensional binomial lattice. We compute the trigger investment cost, i.e., the threshold level below which immediate investment would be optimal. We analyze the major drivers of this decision thus aiming at the most promising policies in this regard. PMID:23295678
Flow Diode and Method for Controlling Fluid Flow Origin of the Invention
NASA Technical Reports Server (NTRS)
Dyson, Rodger W (Inventor)
2015-01-01
A flow diode configured to permit fluid flow in a first direction while preventing fluid flow in a second direction opposite the first direction is disclosed. The flow diode prevents fluid flow without use of mechanical closures or moving parts. The flow diode utilizes a bypass flowline whereby all fluid flow in the second direction moves into the bypass flowline having a plurality of tortuous portions providing high fluidic resistance. The portions decrease in diameter such that debris in the fluid is trapped. As fluid only travels in one direction through the portions, the debris remains trapped in the portions.
Initial cash/asset ratio and asset prices: An experimental study
Caginalp, Gunduz; Porter, David; Smith, Vernon
1998-01-01
A series of experiments, in which nine participants trade an asset over 15 periods, test the hypothesis that an initial imbalance of asset/cash will influence the trading price over an extended time. Participants know at the outset that the asset or “stock” pays a single dividend with fixed expectation value at the end of the 15th period. In experiments with a greater total value of cash at the start, the mean prices during the trading periods are higher, compared with those with greater amount of asset, with a high degree of statistical significance. The difference is most significant at the outset and gradually tapers near the end of the experiment. The results are very surprising from a rational expectations and classical game theory perspective, because the possession of a large amount of cash does not lead to a simple motivation for a trader to bid excessively on a financial instrument. The gradual erosion of the difference toward the end of trading, however, suggests that fundamental value is approached belatedly, offering some consolation to the rational expectations theory. It also suggests that there is a time scale on which an evolution toward fundamental value occurs. The experimental results are qualitatively compatible with the price dynamics predicted by a system of differential equations based on asset flow. The results have broad implications for the marketing of securities, particularly initial and secondary public offerings, government bonds, etc., where excess supply has been conjectured to suppress prices. PMID:11038619
Asymptotic and Numerical Methods for Rapidly Rotating Buoyant Flow
NASA Astrophysics Data System (ADS)
Grooms, Ian G.
This thesis documents three investigations carried out in pursuance of a doctoral degree in applied mathematics at the University of Colorado (Boulder). The first investigation concerns the properties of rotating Rayleigh-Benard convection -- thermal convection in a rotating infinite plane layer between two constant-temperature boundaries. It is noted that in certain parameter regimes convective Taylor columns appear which dominate the dynamics, and a semi-analytical model of these is presented. Investigation of the columns and of various other properties of the flow is ongoing. The second investigation concerns the interactions between planetary-scale and mesoscale dynamics in the oceans. Using multiple-scale asymptotics the possible connections between planetary geostrophic and quasigeostrophic dynamics are investigated, and three different systems of coupled equations are derived. Possible use of these equations in conjunction with the method of superparameterization, and extension of the asymptotic methods to the interactions between mesoscale and submesoscale dynamics is ongoing. The third investigation concerns the linear stability properties of semi-implicit methods for the numerical integration of ordinary differential equations, focusing in particular on the linear stability of IMEX (Implicit-Explicit) methods and exponential integrators applied to systems of ordinary differential equations arising in the numerical solution of spatially discretized nonlinear partial differential equations containing both dispersive and dissipative linear terms. While these investigations may seem unrelated at first glance, some reflection shows that they are in fact closely linked. The investigation of rotating convection makes use of single-space, multiple-time-scale asymptotics to deal with dynamics strongly constrained by rotation. Although the context of thermal convection in an infinite layer seems somewhat removed from large-scale ocean dynamics, the asymptotic
Valuing instream flows using the hedonic price method
NASA Astrophysics Data System (ADS)
Netusil, Noelwah R.; Summers, Matthew T.
2009-11-01
The Oregon Water Trust (OWT) uses a market-based approach to protect and enhance instream flows in Oregon. We use the hedonic price method to estimate the effect of numerous variables on the annualized price OWT pays for water rights: the amount of water protected by the transaction, transaction type (state approved or contractual agreement), presence of anadromous and/or resident fish, and if a fish is listed under the Endangered Species Act (ESA). We find evidence of a premium for state-approved transactions and for transactions that protect water in streams with listed species. Adjusting the amount of water protected by each transaction to include only rights that will be delivered with a high degree of certainty produces coefficient estimates that are similar, but more accurate, than using unadjusted water rights amounts.
Convection in Multiphase Fluid Flows Using Lattice Boltzmann Methods
NASA Astrophysics Data System (ADS)
Biferale, L.; Perlekar, P.; Sbragaglia, M.; Toschi, F.
2012-03-01
We present high-resolution numerical simulations of convection in multiphase flows (boiling) using a novel algorithm based on a lattice Boltzmann method. We first study the thermodynamical and kinematic properties of the algorithm. Then, we perform a series of 3D numerical simulations changing the mean properties in the phase diagram and compare convection with and without phase coexistence at Rayleigh number Ra˜107. We show that in the presence of nucleating bubbles non-Oberbeck-Boussinesq effects develop, the mean temperature profile becomes asymmetric, and heat-transfer and heat-transfer fluctuations are enhanced, at all Ra studied. We also show that small-scale properties of velocity and temperature fields are strongly affected by the presence of the buoyant bubble leading to high non-Gaussian profiles in the bulk.
Design of a Variational Multiscale Method for Turbulent Compressible Flows
NASA Technical Reports Server (NTRS)
Diosady, Laslo Tibor; Murman, Scott M.
2013-01-01
A spectral-element framework is presented for the simulation of subsonic compressible high-Reynolds-number flows. The focus of the work is maximizing the efficiency of the computational schemes to enable unsteady simulations with a large number of spatial and temporal degrees of freedom. A collocation scheme is combined with optimized computational kernels to provide a residual evaluation with computational cost independent of order of accuracy up to 16th order. The optimized residual routines are used to develop a low-memory implicit scheme based on a matrix-free Newton-Krylov method. A preconditioner based on the finite-difference diagonalized ADI scheme is developed which maintains the low memory of the matrix-free implicit solver, while providing improved convergence properties. Emphasis on low memory usage throughout the solver development is leveraged to implement a coupled space-time DG solver which may offer further efficiency gains through adaptivity in both space and time.
38 CFR 6.16 - Payment of cash value in monthly installments.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 38 Pensions, Bonuses, and Veterans' Relief 1 2011-07-01 2011-07-01 false Payment of cash value in... AFFAIRS UNITED STATES GOVERNMENT LIFE INSURANCE Cash Value § 6.16 Payment of cash value in monthly installments. Effective January 1, 1971, in lieu of payment of cash value in one sum, the insured may elect...
38 CFR 6.16 - Payment of cash value in monthly installments.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Payment of cash value in... AFFAIRS UNITED STATES GOVERNMENT LIFE INSURANCE Cash Value § 6.16 Payment of cash value in monthly installments. Effective January 1, 1971, in lieu of payment of cash value in one sum, the insured may elect...
A general method to determine the stability of compressible flows
NASA Technical Reports Server (NTRS)
Guenther, R. A.; Chang, I. D.
1982-01-01
Several problems were studied using two completely different approaches. The initial method was to use the standard linearized perturbation theory by finding the value of the individual small disturbance quantities based on the equations of motion. These were serially eliminated from the equations of motion to derive a single equation that governs the stability of fluid dynamic system. These equations could not be reduced unless the steady state variable depends only on one coordinate. The stability equation based on one dependent variable was found and was examined to determine the stability of a compressible swirling jet. The second method applied a Lagrangian approach to the problem. Since the equations developed were based on different assumptions, the condition of stability was compared only for the Rayleigh problem of a swirling flow, both examples reduce to the Rayleigh criterion. This technique allows including the viscous shear terms which is not possible in the first method. The same problem was then examined to see what effect shear has on stability.
A Method of Detecting Fire Smoke by Using Optical Flow
NASA Astrophysics Data System (ADS)
Terada, Kenji; Miyahara, Hiroyuki; Nii, Yasutoshi
In this paper, the authors propose a method for detecting fire smoke by using the optical flow. This method is not influenced against the image obtainment environment. About 60,000 fires have occurred every year in Japan. To be most important to the fires is an early period fire fighting. At present, the automatic devices of detectiong fires is needed. The alarms which can detect smoke and heat are utilized to house fires. However, these alarms are not useful for the outside of house such as the incendiary or woodland fire. This method is able to detect such a flame that becomes a fire is the early period. First, the region of the flame in the images obtained from the observation camera is detected. Next, the characteristic quantity that expresses the smoke is extracted. This characteristic is not influenced to the motion such as the cloud, leaf and moving objects. In other words, the only smoke can be detected, from the range which looks like the flame in the image.
NASA Technical Reports Server (NTRS)
Chang, J. L. C.; Rosen, R.; Dao, S. C.; Kwak, D.
1985-01-01
An implicit finite difference code cast in general curvilinear coordinates is further developed for three-dimensional incompressible turbulent flows. The code is based on the method of pseudocompressibility and utilizes the Beam and Warming implicit approximate factorization algorithm to achieve computational efficiency. A multiple-zone method is further extended to include composite-grids to overcome the excessive computer memory required for solving turbulent flows in complex three-dimensional geometries. A simple turbulence model is proposed for internal flows. The code is being used for the Space Shuttle Main Engine (SSME) internal flow analyses.
47 CFR 32.1120 - Cash and equivalents.
Code of Federal Regulations, 2010 CFR
2010-10-01
... securities and deposited with trustees to be held until invested in physical property of the company or for... investing cash, such as time drafts receivable and time loans, bankers' acceptances, United States...
47 CFR 32.1120 - Cash and equivalents.
Code of Federal Regulations, 2011 CFR
2011-10-01
... securities and deposited with trustees to be held until invested in physical property of the company or for... investing cash, such as time drafts receivable and time loans, bankers' acceptances, United States...
47 CFR 32.1120 - Cash and equivalents.
Code of Federal Regulations, 2012 CFR
2012-10-01
... securities and deposited with trustees to be held until invested in physical property of the company or for... investing cash, such as time drafts receivable and time loans, bankers' acceptances, United States...
47 CFR 32.1120 - Cash and equivalents.
Code of Federal Regulations, 2014 CFR
2014-10-01
... securities and deposited with trustees to be held until invested in physical property of the company or for... investing cash, such as time drafts receivable and time loans, bankers' acceptances, United States...
42 CFR 436.110 - Individuals receiving cash assistance.
Code of Federal Regulations, 2010 CFR
2010-10-01
... Medicaid agency must provide Medicaid to individuals receiving cash assistance under OAA, AFDC, AB, APTD... the home is considered essential to the well-being of a recipient under the State's plan for OAA,...
40 CFR 35.3160 - Cash draw rules.
Code of Federal Regulations, 2013 CFR
2013-07-01
... STATE AND LOCAL ASSISTANCE State Water Pollution Control Revolving Funds § 35.3160 Cash draw rules. (a... provide substantially more assistance; and (iv) The long term viability of the State program to meet...
40 CFR 35.3160 - Cash draw rules.
Code of Federal Regulations, 2012 CFR
2012-07-01
... STATE AND LOCAL ASSISTANCE State Water Pollution Control Revolving Funds § 35.3160 Cash draw rules. (a... provide substantially more assistance; and (iv) The long term viability of the State program to meet...
40 CFR 35.3160 - Cash draw rules.
Code of Federal Regulations, 2014 CFR
2014-07-01
... STATE AND LOCAL ASSISTANCE State Water Pollution Control Revolving Funds § 35.3160 Cash draw rules. (a... provide substantially more assistance; and (iv) The long term viability of the State program to meet...
40 CFR 35.3160 - Cash draw rules.
Code of Federal Regulations, 2010 CFR
2010-07-01
... STATE AND LOCAL ASSISTANCE State Water Pollution Control Revolving Funds § 35.3160 Cash draw rules. (a... provide substantially more assistance; and (iv) The long term viability of the State program to meet...
A proposed through-flow inverse method for the design of mixed-flow pumps
NASA Technical Reports Server (NTRS)
Borges, Joao Eduardo
1991-01-01
A through-flow (hub-to-shroud) truly inverse method is proposed and described. It uses an imposition of mean swirl, i.e., radius times mean tangential velocity, given throughout the meridional section of the turbomachine as an initial design specification. In the present implementation, it is assumed that the fluid is inviscid, incompressible, and irrotational at inlet and that the blades are supposed to have zero thickness. Only blade rows that impart to the fluid a constant work along the space are considered. An application of this procedure to design the rotor of a mixed-flow pump is described in detail. The strategy used to find a suitable mean swirl distribution and the other design inputs is also described. The final blade shape and pressure distributions on the blade surface are presented, showing that it is possible to obtain feasible designs using this technique. Another advantage of this technique is the fact that it does not require large amounts of CPU time.
Flow in experimental berry aneurysms: method and model.
Kerber, C W; Heilman, C B
1983-01-01
This study addresses two basic questions: What are the flow dynamics in aneurysms? Can these flows be modified to enhance retention of adhesive? Using Pyrex glass bifurcations, fluid flow was studied in a variety of aneurysms placed at varying positions around the bifurcations. Indicators injected into the slipstreams were recorded and studied both by stop-frame high-speed movie analysis and with 35 mm slides. Even at low-flow rates, a central slipstream strikes the apex of bifurcations, and may be partly responsible for the initial production of berry aneurysms. A low-pressure zone occurs at the lateral angle of bifurcations, probably explaining the formation of endovascular cushions. Flow into symmetrically placed narrow neck aneurysms did not occur. Indicator entered the aneurysm in a turbulent fashion only when there was orifice (lip) asymmetry. Both lip asymmetry and rapid flow favor intraaneurysmal turbulent flow. PMID:6410748
Consistent lattice Boltzmann methods for incompressible axisymmetric flows.
Zhang, Liangqi; Yang, Shiliang; Zeng, Zhong; Yin, Linmao; Zhao, Ya; Chew, Jia Wei
2016-08-01
In this work, consistent lattice Boltzmann (LB) methods for incompressible axisymmetric flows are developed based on two efficient axisymmetric LB models available in the literature. In accord with their respective original models, the proposed axisymmetric models evolve within the framework of the standard LB method and the source terms contain no gradient calculations. Moreover, the incompressibility conditions are realized with the Hermite expansion, thus the compressibility errors arising in the existing models are expected to be reduced by the proposed incompressible models. In addition, an extra relaxation parameter is added to the Bhatnagar-Gross-Krook collision operator to suppress the effect of the ghost variable and thus the numerical stability of the present models is significantly improved. Theoretical analyses, based on the Chapman-Enskog expansion and the equivalent moment system, are performed to derive the macroscopic equations from the LB models and the resulting truncation terms (i.e., the compressibility errors) are investigated. In addition, numerical validations are carried out based on four well-acknowledged benchmark tests and the accuracy and applicability of the proposed incompressible axisymmetric LB models are verified. PMID:27627407
Consistent lattice Boltzmann methods for incompressible axisymmetric flows
NASA Astrophysics Data System (ADS)
Zhang, Liangqi; Yang, Shiliang; Zeng, Zhong; Yin, Linmao; Zhao, Ya; Chew, Jia Wei
2016-08-01
In this work, consistent lattice Boltzmann (LB) methods for incompressible axisymmetric flows are developed based on two efficient axisymmetric LB models available in the literature. In accord with their respective original models, the proposed axisymmetric models evolve within the framework of the standard LB method and the source terms contain no gradient calculations. Moreover, the incompressibility conditions are realized with the Hermite expansion, thus the compressibility errors arising in the existing models are expected to be reduced by the proposed incompressible models. In addition, an extra relaxation parameter is added to the Bhatnagar-Gross-Krook collision operator to suppress the effect of the ghost variable and thus the numerical stability of the present models is significantly improved. Theoretical analyses, based on the Chapman-Enskog expansion and the equivalent moment system, are performed to derive the macroscopic equations from the LB models and the resulting truncation terms (i.e., the compressibility errors) are investigated. In addition, numerical validations are carried out based on four well-acknowledged benchmark tests and the accuracy and applicability of the proposed incompressible axisymmetric LB models are verified.
Preconditioned Conjugate Gradient methods for low speed flow calculations
NASA Technical Reports Server (NTRS)
Ajmani, Kumud; Ng, Wing-Fai; Liou, Meng-Sing
1993-01-01
An investigation is conducted into the viability of using a generalized Conjugate Gradient-like method as an iterative solver to obtain steady-state solutions of very low-speed fluid flow problems. Low-speed flow at Mach 0.1 over a backward-facing step is chosen as a representative test problem. The unsteady form of the two dimensional, compressible Navier-Stokes equations are integrated in time using discrete time-steps. The Navier-Stokes equations are cast in an implicit, upwind finite-volume, flux split formulation. The new iterative solver is used to solve a linear system of equations at each step of the time-integration. Preconditioning techniques are used with the new solver to enhance the stability and the convergence rate of the solver and are found to be critical to the overall success of the solver. A study of various preconditioners reveals that a preconditioner based on the lower-upper (L-U)-successive symmetric over-relaxation iterative scheme is more efficient than a preconditioner based on incomplete L-U factorizations of the iteration matrix. The performance of the new preconditioned solver is compared with a conventional line Gauss-Seidel relaxation (LGSR) solver. Overall speed-up factors of 28 (in terms of global time-steps required to converge to a steady-state solution) and 20 (in terms of total CPU time on one processor of a CRAY-YMP) are found in favor of the new preconditioned solver, when compared with the LGSR solver.
Devices and methods of operation thereof for providing stable flow for centrifugal compressors
NASA Technical Reports Server (NTRS)
Skoch, Gary J. (Inventor); Stevens, Mark A. (Inventor); Jett, Thomas A. (Inventor)
2008-01-01
Centrifugal compressor flow stabilizing devices and methods of operation thereof are disclosed that act upon the flow field discharging from the impeller of a centrifugal compressor and modify the flow field ahead of the diffuser vanes such that flow conditions contributing to rotating stall and surge are reduced or even eliminated. In some embodiments, shaped rods and methods of operation thereof are disclosed, whereas in other embodiments reverse-tangent air injection devices and methods are disclosed.
Analysis of methods to estimate spring flows in a karst aquifer
Sepulveda, N.
2009-01-01
Hydraulically and statistically based methods were analyzed to identify the most reliable method to predict spring flows in a karst aquifer. Measured water levels at nearby observation wells, measured spring pool altitudes, and the distance between observation wells and the spring pool were the parameters used to match measured spring flows. Measured spring flows at six Upper Floridan aquifer springs in central Florida were used to assess the reliability of these methods to predict spring flows. Hydraulically based methods involved the application of the Theis, Hantush-Jacob, and Darcy-Weisbach equations, whereas the statistically based methods were the multiple linear regressions and the technology of artificial neural networks (ANNs). Root mean square errors between measured and predicted spring flows using the Darcy-Weisbach method ranged between 5% and 15% of the measured flows, lower than the 7% to 27% range for the Theis or Hantush-Jacob methods. Flows at all springs were estimated to be turbulent based on the Reynolds number derived from the Darcy-Weisbach equation for conduit flow. The multiple linear regression and the Darcy-Weisbach methods had similar spring flow prediction capabilities. The ANNs provided the lowest residuals between measured and predicted spring flows, ranging from 1.6% to 5.3% of the measured flows. The model prediction efficiency criteria also indicated that the ANNs were the most accurate method predicting spring flows in a karst aquifer. ?? 2008 National Ground Water Association.
On numerical methods in non-Newtonian flows
NASA Astrophysics Data System (ADS)
Fileas, G.
1982-12-01
The constitutive equations for non-Newtonian flows are presented and the various flow models derived from continuum mechanics and molecular theories are considered and evaluated. Detailed account is given of numerical simulation employing differential and integral models of different kinds of non-Newtonian flows using finite difference and finite element techniques. Procedures for computer set ups are described and references are given for finite difference, finite element and molecular theory based programs for several kinds of flow. Achievements and unreached goals in the field of numerical simulation of non-Newtonian flows are discussed and the lack of numerical work in the fields of suspension flows and heat transfer is pointed out. Finally, FFOCUS is presented as a newly built computer program which can simulate freezing flows of Newtonian fluids through various geometries and is aimed to be further developed to handle non-Newtonian freezing flows and certain types of suspension phenomena involved in corium flow after a hypothetical core melt down accident in a pressurized water reactor.
Calculation of unsteady transonic flows using the integral equation method
NASA Technical Reports Server (NTRS)
Nixon, D.
1978-01-01
The basic integral equations for a harmonically oscillating airfoil in a transonic flow with shock waves are derived; the reduced frequency is assumed to be small. The problems associated with shock wave motion are treated using a strained coordinate system. The integral equation is linear and consists of both line integrals and surface integrals over the flow field which are evaluated by quadrature. This leads to a set of linear algebraic equations that can be solved directly. The shock motion is obtained explicitly by enforcing the condition that the flow is continuous except at a shock wave. Results obtained for both lifting and nonlifting oscillatory flows agree satisfactorily with other accurate results.
Testing the instream flow method in trout streams
Studley, T.K.; Railsback, S.F.; Asce, M.
1995-12-31
Pacific Gas and Electric Company`s (PG&E) Department of Research and Development and co-sponsors are fieldtesting the Instream Flow Incremental Methodology (IFIM) at a number of trout stream study sites. Fish populations, flows, and other variables were measured for an eight-year baseline period. Three levels of increasingly sophisticated predictions of population response to increased flows were made. The flow increases have been implemented and additional data are being collected to test the predictions. The baseline data and prediction analyses indicate that (1) using different habitat suitability criteria produces substantially different predictions of how populations respond to flow changes, (2) overlaps in habitat used by trout species can lead to misleading predictions of a population`s response to flow changes, and (3) factors other than habitat during summer low flows can limit trout populations (these include spawning habitat, high flows, stream channel characteristics, and stream temperature). Comprehensive field studies are expensive, but are more likely to result in instream flows that provide a cost-effective tradeoff between power and fisheries values.
Methods for the calculation of axial wave numbers in lined ducts with mean flow
NASA Technical Reports Server (NTRS)
Eversman, W.
1981-01-01
A survey is made of the methods available for the calculation of axial wave numbers in lined ducts. Rectangular and circular ducts with both uniform and non-uniform flow are considered as are ducts with peripherally varying liners. A historical perspective is provided by a discussion of the classical methods for computing attenuation when no mean flow is present. When flow is present these techniques become either impractical or impossible. A number of direct eigenvalue determination schemes which have been used when flow is present are discussed. Methods described are extensions of the classical no-flow technique, perturbation methods based on the no-flow technique, direct integration methods for solution of the eigenvalue equation, an integration-iteration method based on the governing differential equation for acoustic transmission, Galerkin methods, finite difference methods, and finite element methods.
Axial and Centrifugal Compressor Mean Line Flow Analysis Method
NASA Technical Reports Server (NTRS)
Veres, Joseph P.
2009-01-01
This paper describes a method to estimate key aerodynamic parameters of single and multistage axial and centrifugal compressors. This mean-line compressor code COMDES provides the capability of sizing single and multistage compressors quickly during the conceptual design process. Based on the compressible fluid flow equations and the Euler equation, the code can estimate rotor inlet and exit blade angles when run in the design mode. The design point rotor efficiency and stator losses are inputs to the code, and are modeled at off design. When run in the off-design analysis mode, it can be used to generate performance maps based on simple models for losses due to rotor incidence and inlet guide vane reset angle. The code can provide an improved understanding of basic aerodynamic parameters such as diffusion factor, loading levels and incidence, when matching multistage compressor blade rows at design and at part-speed operation. Rotor loading levels and relative velocity ratio are correlated to the onset of compressor surge. NASA Stage 37 and the three-stage NASA 74-A axial compressors were analyzed and the results compared to test data. The code has been used to generate the performance map for the NASA 76-B three-stage axial compressor featuring variable geometry. The compressor stages were aerodynamically matched at off-design speeds by adjusting the variable inlet guide vane and variable stator geometry angles to control the rotor diffusion factor and incidence angles.
Quadrature Moments Method for the Simulation of Turbulent Reactive Flows
NASA Technical Reports Server (NTRS)
Raman, Venkatramanan; Pitsch, Heinz; Fox, Rodney O.
2003-01-01
A sub-filter model for reactive flows, namely the DQMOM model, was formulated for Large Eddy Simulation (LES) using the filtered mass density function. Transport equations required to determine the location and size of the delta-peaks were then formulated for a 2-peak decomposition of the FDF. The DQMOM scheme was implemented in an existing structured-grid LES solver. Simulations of scalar shear layer using an experimental configuration showed that the first and second moments of both reactive and inert scalars are in good agreement with a conventional Lagrangian scheme that evolves the same FDF. Comparisons with LES simulations performed using laminar chemistry assumption for the reactive scalar show that the new method provides vast improvements at minimal computational cost. Currently, the DQMOM model is being implemented for use with the progress variable/mixture fraction model of Pierce. Comparisons with experimental results and LES simulations using a single-environment for the progress-variable are planned. Future studies will aim at understanding the effect of increase in environments on predictions.
The least-squares finite element method for low-mach-number compressible viscous flows
NASA Technical Reports Server (NTRS)
Yu, Sheng-Tao
1994-01-01
The present paper reports the development of the Least-Squares Finite Element Method (LSFEM) for simulating compressible viscous flows at low Mach numbers in which the incompressible flows pose as an extreme. Conventional approach requires special treatments for low-speed flows calculations: finite difference and finite volume methods are based on the use of the staggered grid or the preconditioning technique; and, finite element methods rely on the mixed method and the operator-splitting method. In this paper, however, we show that such difficulty does not exist for the LSFEM and no special treatment is needed. The LSFEM always leads to a symmetric, positive-definite matrix through which the compressible flow equations can be effectively solved. Two numerical examples are included to demonstrate the method: first, driven cavity flows at various Reynolds numbers; and, buoyancy-driven flows with significant density variation. Both examples are calculated by using full compressible flow equations.
Method for flow cytometric monitoring of Renibacterium salmoninarum inactivation
Pascho, R.J.; Ongerth, J.E.
2000-01-01
with bacteriological culture (r2 ??? 0.22). In both assessments, there was a correlation between the estimates of inactivation based upon HRFI and CS analyses (r2 > 0.99). These results suggest that flow cytometry can be used as a supplementary or alternative method to bacteriological culture for monitoring the inactivation of R. salmoninarum.
Method for flow cytometric monitoring of Renibacterium salmoninarum inactivation.
Pascho, R J; Ongerth, J E
2000-07-14
estimates correlated with bacteriological culture (r2 < or = 0.22). In both assessments, there was a correlation between the estimates of inactivation based upon HRFI and CS analyses (r2 > 0.99). These results suggest that flow cytometry can be used as a supplementary or alternative method to bacteriological culture for monitoring the inactivation of R. salmoninarum. PMID:10950180
A velocity-correction projection method based immersed boundary method for incompressible flows
NASA Astrophysics Data System (ADS)
Cai, Shanggui
2014-11-01
In the present work we propose a novel direct forcing immersed boundary method based on the velocity-correction projection method of [J.L. Guermond, J. Shen, Velocity-correction projection methods for incompressible flows, SIAM J. Numer. Anal., 41 (1)(2003) 112]. The principal idea of immersed boundary method is to correct the velocity in the vicinity of the immersed object by using an artificial force to mimic the presence of the physical boundaries. Therefore, velocity-correction projection method is preferred to its pressure-correction counterpart in the present work. Since the velocity-correct projection method is considered as a dual class of pressure-correction method, the proposed method here can also be interpreted in the way that first the pressure is predicted by treating the viscous term explicitly without the consideration of the immersed boundary, and the solenoidal velocity is used to determine the volume force on the Lagrangian points, then the non-slip boundary condition is enforced by correcting the velocity with the implicit viscous term. To demonstrate the efficiency and accuracy of the proposed method, several numerical simulations are performed and compared with the results in the literature. China Scholarship Council.
Effect of gas flow swirling on coating deposition by the cold gas-dynamic spray method
NASA Astrophysics Data System (ADS)
Kiselev, S. P.; Kiselev, V. P.; Zaikovskii, V. N.
2012-03-01
The effect of gas flow swirling on the process of coating deposition onto a target by the cold gas-dynamic spray method is studied experimentally and numerically. Flow swirling is found to change the gas flow field and to reduce the gas flow rate under typical conditions of cold gas-dynamic spray. In a non-swirled flow, the shape of the deposited spot is similar to a sharp cone. In contrast, the deposited spot in a swirled flow is shaped as a crater without particles at the center of this crater. It is found that this effect is caused by centrifugal forces acting on particles in a swirled gas flow.
A numerical method for a model of two-phase flow in a coupled free flow and porous media system
NASA Astrophysics Data System (ADS)
Chen, Jie; Sun, Shuyu; Wang, Xiao-Ping
2014-07-01
In this article, we study two-phase fluid flow in coupled free flow and porous media regions. The model consists of coupled Cahn-Hilliard and Navier-Stokes equations in the free fluid region and the two-phase Darcy law in the porous medium region. We propose a Robin-Robin domain decomposition method for the coupled Navier-Stokes and Darcy system with the generalized Beavers-Joseph-Saffman condition on the interface between the free flow and the porous media regions. Numerical examples are presented to illustrate the effectiveness of this method.
Itzel, Gary Michael; Devine, II, Robert Henry; Chopra, Sanjay; Toornman, Thomas Nelson
2003-07-08
A coolant flow control structure is provided to channel cooling media flow to the fillet region defined at the transition between the wall of a nozzle vane and a wall of a nozzle segment, for cooling the fillet region. In an exemplary embodiment, the flow control structure defines a gap with the fillet region to achieve the required heat transfer coefficients in this region to meet part life requirements.
Piecewise uniform conduction-like flow channels and method therefor
Cummings, Eric B.; Fiechtner, Gregory J.
2006-02-28
A low-dispersion methodology for designing microfabricated conduction channels for on-chip electrokinetic-based systems is presented. The technique relies on trigonometric relations that apply for ideal electrokinetic flows, allowing faceted channels to be designed on chips using common drafting software and a hand calculator. Flows are rotated and stretched along the abrupt interface between adjacent regions with differing permeability. Regions bounded by interfaces form flow "prisms" that can be combined with other designed prisms to obtain a wide range of turning angles and expansion ratios while minimizing dispersion. Designs are demonstrated using two-dimensional numerical solutions of the Laplace equation.
Method and applications of fiber synthesis using laminar flow
NASA Astrophysics Data System (ADS)
Burns, Bradley Justin
A Laminar Flow Reactor (LFR) using the principles of hydrodynamic focusing was created and used to fabricate functional composite polymer fibers. These fibers had the ability to conduct or serve as a carrier for singlet oxygen-generating molecules. Critical to the process was designing an easy-to-fabricate, inexpensive device and developing a repeatable method that made efficient use of the materials. The initial designs used a planar layout and hydrodynamically focused in only one dimension while later versions switched to a two-fluid concentric design. Modeling was undertaken and verified for the different device layouts. Three types of conductive particles were embedded in the formed polymer: silver, indium tin oxide (ITO) and polyaniline. The polymer was also used as a carrier to two singlet oxygen generating molecules: Methylene Blue (MB) and perylene. Both were effective in killing Bacillus thuringiensis but MB leached from the fiber into the tested cell suspension. Perylene, which is not water soluble, did not leach out and was just as effective as MB. Research that was performed at ITT is also presented. A critical need exists to detect, identify, quantify, locate, and track virus and toxin aerosols to provide early warning during both light and dark conditions. The solution presented is a remote sensing technology using seeding particles. Seeding particles developed during this program provide specific identification of threat cloud content. When introduced to the threat cloud the seeders will bind specifically to the analyte of interest and upon interrogation from a stand off laser source will fluoresce. The fluorescent signal is detected from a distance using a long-range microscope and collection optics that allow detection of low concentrations of threat aerosols.
Base flow separation: A comparison of analytical and mass balance methods
NASA Astrophysics Data System (ADS)
Lott, Darline A.; Stewart, Mark T.
2016-04-01
Base flow is the ground water contribution to stream flow. Many activities, such as water resource management, calibrating hydrological and climate models, and studies of basin hydrology, require good estimates of base flow. The base flow component of stream flow is usually determined by separating a stream hydrograph into two components, base flow and runoff. Analytical methods, mathematical functions or algorithms used to calculate base flow directly from discharge, are the most widely used base flow separation methods and are often used without calibration to basin or gage-specific parameters other than basin area. In this study, six analytical methods are compared to a mass balance method, the conductivity mass-balance (CMB) method. The base flow index (BFI) values for 35 stream gages are obtained from each of the seven methods with each gage having at least two consecutive years of specific conductance data and 30 years of continuous discharge data. BFI is cumulative base flow divided by cumulative total discharge over the period of record of analysis. The BFI value is dimensionless, and always varies from 0 to 1. Areas of basins used in this study range from 27 km2 to 68,117 km2. BFI was first determined for the uncalibrated analytical methods. The parameters of each analytical method were then calibrated to produce BFI values as close to the CMB derived BFI values as possible. One of the methods, the power function (aQb + cQ) method, is inherently calibrated and was not recalibrated. The uncalibrated analytical methods have an average correlation coefficient of 0.43 when compared to CMB-derived values, and an average correlation coefficient of 0.93 when calibrated with the CMB method. Once calibrated, the analytical methods can closely reproduce the base flow values of a mass balance method. Therefore, it is recommended that analytical methods be calibrated against tracer or mass balance methods.
Development of a flow rate monitoring method for the wearable ventricular assist device driver.
Ohnuma, Kentaro; Homma, Akihiko; Sumikura, Hirohito; Tsukiya, Tomonori; Takewa, Yoshiaki; Mizuno, Toshihide; Mukaibayashi, Hiroshi; Kojima, Koichi; Katano, Kazuo; Taenaka, Yoshiyuki; Tatsumi, Eisuke
2015-06-01
Our research institute has been working on the development of a compact wearable drive unit for an extracorporeal ventricular assist device (VAD) with a pneumatically driven pump. A method for checking the pump blood flow on the side of the drive unit without modifying the existing blood pump and impairing the portability of it will be useful. In this study, to calculate the pump flow rate indirectly from measuring the flow rate of the driving air of the VAD air chamber, we conducted experiments using a mock circuit to investigate the correlation between the air flow rate and the pump flow rate as well as its accuracy and error factors. The pump flow rate was measured using an ultrasonic flow meter at the inflow and outflow tube, and the air flow was measured using a thermal mass flow meter at the driveline. Similarity in the instantaneous waveform was confirmed between the air flow rate in the driveline and the pump flow rate. Some limitations of this technique were indicated by consideration of the error factors. A significant correlation was found between the average pump flow rate in the ejecting direction and the average air flow rate in the ejecting direction (R2 = 0.704-0.856), and the air flow rate in the filling direction (R2 = 0.947-0.971). It was demonstrated that the average pump flow rate was estimated exactly in a wide range of drive conditions using the air flow of the filling phase. PMID:25500948
Flow prediction for three-dimensional intakes and ducts using viscous-inviscid interaction methods
NASA Astrophysics Data System (ADS)
Wrisdale, Ian Edward
1991-02-01
A numerical scheme for the prediction of flows in engine intakes is presented. The scheme, which employs a viscous-inviscid interaction approach, is aimed at the treatment of high Reynolds number flows in which a significant region of inviscid core flow exists in the intake. The scheme is restricted to the treatment of attached flows; however, it is suitable for the treatment of highly rotational flows. The subsonic core flow calculations in the intake duct are performed using an Euler space marching scheme. Accurate flow prediction using the scheme requires the specification of detailed boundary conditions at the inlet plane of the duct. Appropriate conditions have been obtained by using a finite volume time marching scheme to calculate the flow field around inlet cowls at incidence. Hence, the boundary conditions for the duct calculations take account of the lip flows which are dependent on free stream conditions, incidence, and the mass flow ratio. Careful matching of the cowl and duct calculations provides a solution of the complete inviscid flow field both internal and external. The viscous-inviscid interaction scheme couples the inviscid solutions to a fully three-dimensional boundary layer method using a displacement surface model. The integral boundary layer method is aimed at the treatment of attached, turbulent boundary layers and includes the effects of rotational outer flows. Although the method is restricted to attached flows it may be used to indicate the onset of three-dimensional flow separation. The coupling of the inviscid flows and the boundary layers on the internal and external surface of the intake provide a complete description of the entire flow field. Numerical examples are presented throughout the work to illustrate the various methods. The complete scheme is then used to calculate the flow in an S-shaped intake duct operating under choked conditions at varying angles of incidence.
Robertson, Laura; Mushati, Phyllis; Skovdal, Morten; Eaton, Jeffrey W.; Makoni, Jeremiah C.; Crea, Tom; Mavise, Gideon; Dumba, Lovemore; Schumacher, Christina; Sherr, Lorraine; Nyamukapa, Constance; Gregson, Simon
2014-01-01
Summary We used baseline data, collected in July–September 2009, from a randomized controlled trial of a cash transfer program for vulnerable children in eastern Zimbabwe to investigate the effectiveness, coverage, and efficiency of census- and community-based targeting methods for reaching vulnerable children. Focus group discussions and in-depth interviews with beneficiaries and other stakeholders were used to explore community perspectives on targeting. Community members reported that their participation improved ownership and reduced conflict and jealousy. However, all the methods failed to target a large proportion of vulnerable children and there was poor agreement between the community- and census-based methods. PMID:24748713
Imbalance-correction grid-refinement method for lattice Boltzmann flow simulations
NASA Astrophysics Data System (ADS)
Kuwata, Y.; Suga, K.
2016-04-01
To enhance the accuracy and applicability of the zonal grid refinement method for the lattice Boltzmann method, a new method which minimizes the interface imbalances of mass and momentum is developed. This method introduces a correction step for the macroscopic flow variables such as the fluid density and velocity to remove their interface discontinuity. To demonstrate and evaluate the presently developed imbalance correction grid refinement method, large eddy simulations of turbulent channel and square cylinder flows are carried out. By changing the grid arrangement in the turbulent channel flows, it is confirmed that the present method reduces the sensitivity to the location of the grid refinement interface and minimizes the unphysically discontinuous profiles satisfactorily. Furthermore, the present method considerably improves mass conservation of the system, which is particularly important for long time periodical flow simulations. It is also confirmed that the present method generally improves the prediction performance of the square cylinder flows.
Lattice Boltzmann Method for 3-D Flows with Curved Boundary
NASA Technical Reports Server (NTRS)
Mei, Renwei; Shyy, Wei; Yu, Dazhi; Luo, Li-Shi
2002-01-01
In this work, we investigate two issues that are important to computational efficiency and reliability in fluid dynamics applications of the lattice, Boltzmann equation (LBE): (1) Computational stability and accuracy of different lattice Boltzmann models and (2) the treatment of the boundary conditions on curved solid boundaries and their 3-D implementations. Three athermal 3-D LBE models (D3QI5, D3Ql9, and D3Q27) are studied and compared in terms of efficiency, accuracy, and robustness. The boundary treatment recently developed by Filippova and Hanel and Met et al. in 2-D is extended to and implemented for 3-D. The convergence, stability, and computational efficiency of the 3-D LBE models with the boundary treatment for curved boundaries were tested in simulations of four 3-D flows: (1) Fully developed flows in a square duct, (2) flow in a 3-D lid-driven cavity, (3) fully developed flows in a circular pipe, and (4) a uniform flow over a sphere. We found that while the fifteen-velocity 3-D (D3Ql5) model is more prone to numerical instability and the D3Q27 is more computationally intensive, the 63Q19 model provides a balance between computational reliability and efficiency. Through numerical simulations, we demonstrated that the boundary treatment for 3-D arbitrary curved geometry has second-order accuracy and possesses satisfactory stability characteristics.
A direct-inverse method for transonic and separated flows about airfoils
NASA Technical Reports Server (NTRS)
Carlson, Leland A.
1990-01-01
A direct-inverse technique and computer program called TAMSEP that can be used for the analysis of the flow about airfoils at subsonic and low transonic freestream velocities is presented. The method is based upon a direct-inverse nonconservative full potential inviscid method, a Thwaites laminar boundary layer technique, and the Barnwell turbulent momentum integral scheme; and it is formulated using Cartesian coordinates. Since the method utilizes inverse boundary conditions in regions of separated flow, it is suitable for predicting the flow field about airfoils having trailing edge separated flow under high lift conditions. Comparisons with experimental data indicate that the method should be a useful tool for applied aerodynamic analyses.
Spacecraft heat transfer by two-phase flow method
NASA Technical Reports Server (NTRS)
Hye, A.
1985-01-01
A refrigerator/freezer has been designed with an oil-free compressor to provide an economical two-phase flow system for heat transfer. A computer simulation has been done for the condenser and evaporator to determine the design parameters, such as length, diameter, and flow regimes, for different refrigerants and load requirements. A large Reynolds number was considered to ensure annular flow (in order to maximize heat transfer coefficients) and large Froude number. The simulation was correlated with the test data of a vapor compression refrigerator/freezer flown on STS-4 (which provided information on vapor compression in a zero-gravity environment). The two-phase system will be used for the Spacelab mission SLS-1 and can be used in future spacecraft and high-speed aircraft, where weight, volume, and power requirements are critical.
Detailed analysis of POD method applied on turbulent flow
NASA Astrophysics Data System (ADS)
Kellnerova, Radka; Kukacka, Libor; Uruba, Vaclav; Jurcakova, Klara; Janour, Zbynek
2012-04-01
Proper orthogonal decomposition (POD) of a very turbulent flow inside a street canyon is performed. The energy contribution of each mode is obtained. Also, physical meaning of the POD result is clarified. Particular modes of POD are assigned to the particular flow events like a sweep event, a vortex behind a roof or a vortex at the bottom of a street. Test of POD sensitivity to the acquisition time of data records is done. Test with decreasing sample frequency is also executed. Further, interpolation of POD expansion coefficient is performed in order to test possible increase in sample frequency and get new information about the flow from the POD analysis. We tested a linear and a spline type of the interpolation and the linear one carried out a slightly better result.
Method and apparatus for adapting steady flow with cyclic thermodynamics
Swift, Gregory W.; Reid, Robert S.; Ward, William C.
2000-01-01
Energy transfer apparatus has a resonator for supporting standing acoustic waves at a selected frequency with a steady flow process fluid thermodynamic medium and a solid medium having heat capacity. The fluid medium and the solid medium are disposed within the resonator for thermal contact therebetween and for relative motion therebetween. The relative motion is produced by a first means for producing a steady velocity component and second means for producing an oscillating velocity component at the selected frequency and concomitant wavelength of the standing acoustic wave. The oscillating velocity and associated oscillating pressure component provide energy transfer between the steady flow process fluid and the solid medium as the steady flow process fluid moves through the resonator.
Lava flow rheology: A comparison of morphological and petrological methods
NASA Astrophysics Data System (ADS)
Chevrel, M. O.; Platz, T.; Hauber, E.; Baratoux, D.; Lavallée, Y.; Dingwell, D. B.
2013-12-01
In planetary sciences, the emplacement of lava flows is commonly modelled using a single rheological parameter (apparent viscosity or apparent yield strength) calculated from morphological dimensions using Jeffreys' and Hulme's equations. The rheological parameter is then typically further interpreted in terms of the nature and chemical composition of the lava (e.g., mafic or felsic). Without the possibility of direct sampling of the erupted material, the validity of this approach has remained largely untested. In modern volcanology, the complex rheological behaviour of lavas is measured and modelled as a function of chemical composition of the liquid phase, fractions of crystals and bubbles, temperature and strain rate. Here, we test the planetary approach using a terrestrial basaltic lava flow from the Western Volcanic Zone in Iceland. The geometric parameters required to employ Jeffreys' and Hulme's equations are accurately estimated from high-resolution HRSC-AX Digital Elevation Models. Samples collected along the lava flow are used to constrain a detailed model of the transient rheology as a function of cooling, crystallisation, and compositional evolution of the residual melt during emplacement. We observe that the viscosity derived from the morphology corresponds to the value estimated when significant crystallisation inhibits viscous deformation, causing the flow to halt. As a consequence, the inferred viscosity is highly dependent on the details of the crystallisation sequence and crystal shapes, and as such, is neither uniquely nor simply related to the bulk chemical composition of the erupted material. This conclusion, drawn for a mafic lava flow where crystallisation is the primary process responsible for the increase of the viscosity during emplacement, should apply to most of martian, lunar, or mercurian volcanic landforms, which are dominated by basaltic compositions. However, it may not apply to felsic lavas where vitrification resulting from
A New Method for Flow Rate Measurement in Millimeter-Scale Pipes
Ji, Haifeng; Gao, Xuemin; Wang, Baoliang; Huang, Zhiyao; Li, Haiqing
2013-01-01
Combining the Capacitively Coupled Contactless Conductivity Detection (C4D) technique and the principle of cross correlation flow measurement, a new method for flow rate measurement in millimeter-scale pipes was proposed. The research work included two parts. First, a new five-electrode C4D sensor was developed. Second, with two conductivity signals obtained by the developed sensor, the flow rate measurement was implemented by using the principle of cross correlation flow measurement. The experimental results showed that the proposed flow rate measurement method was effective, the developed five-electrode C4D sensor was successful, and the measurement accuracy was satisfactory. In five millimeter-scale pipes with different inner diameters of 0.5, 0.8, 1.8, 3.0 and 3.9 mm respectively, the maximum relative difference of the flow rate measurement between the reference flow rate and the measured flow rate was less than 5%. PMID:23353139
Method for computing three-dimensional turbulent flows
Bernard, P.S.; Berger, B.S.
1982-06-01
The MVC (mean vorticity and covariance) turbulence closure is derived for three-dimensional turbulent flows. The derivation utilizes Lagrangian time expansion techniques applied to the unclosed terms of the mean vorticity and covariance equations. The closed mean vorticity equation is applied to the numerical solution of fully developed three-dimensional channel flow. Anisotropies in the wall region are modelled by pairs of counterrotating streamwise vortices. The numerical results are in close agreement with experimental data. Analysis of the contributions of the terms in the mean vorticity equation gives insight into the dynamics of the turbulent boundary. 41 references, 7 figures.
Applications of domain decomposition methods to turbomachinery flows
NASA Astrophysics Data System (ADS)
Rai, M. M.
Domain decomposition techniques can be used to great advantage by computational fluid dynamicists in computing flows about complex geometries and adapting the grid to the solution. These techniques are particularly useful in computing flows about several bodies that are in relative motion such as rotor/stator configurations in turbomachinery or helicopter rotor/fuselage configurations. This paper discusses some of the basic ideas involved in transferring information between subdomains in a multidomain calculation and presents results for a simple rotor/stator configuration.
Computational Methods for Analyzing Fluid Flow Dynamics from Digital Imagery
Luttman, A.
2012-03-30
The main goal (long term) of this work is to perform computational dynamics analysis and quantify uncertainty from vector fields computed directly from measured data. Global analysis based on observed spatiotemporal evolution is performed by objective function based on expected physics and informed scientific priors, variational optimization to compute vector fields from measured data, and transport analysis proceeding with observations and priors. A mathematical formulation for computing flow fields is set up for computing the minimizer for the problem. An application to oceanic flow based on sea surface temperature is presented.
Divisible E-Cash Systems Can Be Truly Anonymous
NASA Astrophysics Data System (ADS)
Canard, Sébastien; Gouget, Aline
This paper presents an off-line divisible e-cash scheme where a user can withdraw a divisible coin of monetary value 2 L that he can parceled and spend anonymously and unlinkably. We present the construction of a security tag that allows to protect the anonymity of honest users and to revoke anonymity only in case of cheat for protocols based on a binary tree structure without using a trusted third party. This is the first divisible e-cash scheme that provides both full unlinkability and anonymity without requiring a trusted third party.
Simple Radiowave-Based Method For Measuring Peripheral Blood Flow Project
NASA Technical Reports Server (NTRS)
Oliva-Buisson, Yvette J.
2014-01-01
Project objective is to design small radio frequency based flow probes for the measurement of blood flow velocity in peripheral arteries such as the femoral artery and middle cerebral artery. The result will be the technological capability to measure peripheral blood flow rates and flow changes during various environmental stressors such as microgravity without contact to the individual being monitored. This technology may also lead to an easier method of detecting venous gas emboli during extravehicular activities.
A comparison of computational methods for three-dimensional, turbulent turbomachinery flow fields
NASA Technical Reports Server (NTRS)
Kirtley, K. R.; Warfield, M.; Lakshminarayana, B.
1986-01-01
A space-marching method and a time-marching method have been used to compute the three-dimensional turbulent flow in an end wall cascade of airfoils. Using an identical grid and turbulence model, the two codes were used to predict a variety of flow quantities. Predictions by the two methods are compared to each other and to experimental data. In general both methods predict measured quantities well, with a small edge in prediction accuracy going to the space-marching method. Secondary flow comparisons show the time-marching solution more accurately predicting the underturning of the flow in the outer portion of the end wall boundary layer while the space-marching method more accurately predicted the overturning of the flow very near the end wall. The prediction comparisons are discussed along with computational details and other attributes of the two methods.
NASA Astrophysics Data System (ADS)
Blais-Stevens, A.; Behnia, P.
2016-02-01
This research activity aimed at reducing risk to infrastructure, such as a proposed pipeline route roughly parallel to the Yukon Alaska Highway Corridor (YAHC), by filling geoscience knowledge gaps in geohazards. Hence, the Geological Survey of Canada compiled an inventory of landslides including debris flow deposits, which were subsequently used to validate two different debris flow susceptibility models. A qualitative heuristic debris flow susceptibility model was produced for the northern region of the YAHC, from Kluane Lake to the Alaska border, by integrating data layers with assigned weights and class ratings. These were slope angle, slope aspect, surficial geology, plan curvature, and proximity to drainage system. Validation of the model was carried out by calculating a success rate curve which revealed a good correlation with the susceptibility model and the debris flow deposit inventory compiled from air photos, high-resolution satellite imagery, and field verification. In addition, the quantitative Flow-R method was tested in order to define the potential source and debris flow susceptibility for the southern region of Kluane Lake, an area where documented debris flow events have blocked the highway in the past (e.g. 1988). Trial and error calculations were required for this method because there was not detailed information on the debris flows for the YAHC to allow us to define threshold values for some parameters when calculating source areas, spreading, and runout distance. Nevertheless, correlation with known documented events helped define these parameters and produce a map that captures most of the known events and displays debris flow susceptibility in other, usually smaller, steep channels that had not been previously documented.
Study of design and analysis methods for transonic flow
NASA Technical Reports Server (NTRS)
Murman, E. M.
1977-01-01
An airfoil design program and a boundary layer analysis were developed. Boundary conditions were derived for ventilated transonic wind tunnels and performing transonic windtunnel wall calculations. A computational procedure for rotational transonic flow in engine inlet throats was formulated. Results and conclusions are summarized.
Unstructured Mesh Methods for the Simulation of Hypersonic Flows
NASA Technical Reports Server (NTRS)
Peraire, J.
1999-01-01
This report summarizes the research undertaken, at Aeronautics Department of the Massachusetts Institute of Technology, during the approximately five year period, February 94 - March 99. This work is part of a larger effort aimed at providing a reliable fast turn around capability for the prediction of hypersonic flows over complete vehicle configurations.
NASA Technical Reports Server (NTRS)
Zang, Thomas A.; Mathelin, Lionel; Hussaini, M. Yousuff; Bataille, Francoise
2003-01-01
This paper describes a fully spectral, Polynomial Chaos method for the propagation of uncertainty in numerical simulations of compressible, turbulent flow, as well as a novel stochastic collocation algorithm for the same application. The stochastic collocation method is key to the efficient use of stochastic methods on problems with complex nonlinearities, such as those associated with the turbulence model equations in compressible flow and for CFD schemes requiring solution of a Riemann problem. Both methods are applied to compressible flow in a quasi-one-dimensional nozzle. The stochastic collocation method is roughly an order of magnitude faster than the fully Galerkin Polynomial Chaos method on the inviscid problem.
An empirical method for estimating travel times for wet volcanic mass flows
Pierson, Thomas C.
1998-01-01
Travel times for wet volcanic mass flows (debris avalanches and lahars) can be forecast as a function of distance from source when the approximate flow rate (peak discharge near the source) can be estimated beforehand. The near-source flow rate is primarily a function of initial flow volume, which should be possible to estimate to an order of magnitude on the basis of geologic, geomorphic, and hydrologic factors at a particular volcano. Least-squares best fits to plots of flow-front travel time as a function of distance from source provide predictive second-degree polynomial equations with high coefficients of determination for four broad size classes of flow based on near-source flow rate: extremely large flows (>1 000 000 m3/s), very large flows (10 000–1 000 000 m3/s), large flows (1000–10 000 m3/s), and moderate flows (100–1000 m3/s). A strong nonlinear correlation that exists between initial total flow volume and flow rate for "instantaneously" generated debris flows can be used to estimate near-source flow rates in advance. Differences in geomorphic controlling factors among different flows in the data sets have relatively little effect on the strong nonlinear correlations between travel time and distance from source. Differences in flow type may be important, especially for extremely large flows, but this could not be evaluated here. At a given distance away from a volcano, travel times can vary by approximately an order of magnitude depending on flow rate. The method can provide emergency-management officials a means for estimating time windows for evacuation of communities located in hazard zones downstream from potentially hazardous volcanoes.
NASA Astrophysics Data System (ADS)
Kawabata, Jun-ichi; Shi-igai, Hiroyoshi; Yabuno, Kohei; Saito, Tadayuki
1992-06-01
The complex function method is applied to screen printing flow with low Reynolds number assuming that the printing ink is Newtonian. The screen printing flow is expressed through a Taylor flow in the corner. The pressure distribution, vorticity distribution and stream lines of the Taylor flow can easily be obtained by using the complex function method. A new model of the flow which may better express the screen printing is obtained through this method by placing a sink at the origin of the Taylor flow. The appropriate corner angle for printing, theoretically derived from this method as 65.4°, corresponds to the empirical angle in industrial use. The pressure distribution of this model shows good agreement with the experimental results obtained in the present work.
NASA Technical Reports Server (NTRS)
Beatty, T. D.
1975-01-01
A theoretical method is presented for the computation of the flow field about an axisymmetric body operating in a viscous, incompressible fluid. A potential flow method was used to determine the inviscid flow field and to yield the boundary conditions for the boundary layer solutions. Boundary layer effects in the forces of displacement thickness and empirically modeled separation streamlines are accounted for in subsequent potential flow solutions. This procedure is repeated until the solutions converge. An empirical method was used to determine base drag allowing configuration drag to be computed.
General design method for three-dimensional potential flow fields. 1: Theory
NASA Technical Reports Server (NTRS)
Stanitz, J. D.
1980-01-01
A general design method was developed for steady, three dimensional, potential, incompressible or subsonic-compressible flow. In this design method, the flow field, including the shape of its boundary, was determined for arbitrarily specified, continuous distributions of velocity as a function of arc length along the boundary streamlines. The method applied to the design of both internal and external flow fields, including, in both cases, fields with planar symmetry. The analytic problems associated with stagnation points, closure of bodies in external flow fields, and prediction of turning angles in three dimensional ducts were reviewed.
System and method for bidirectional flow and controlling fluid flow in a conduit
Ortiz, Marcos German
1999-01-01
A system for measuring bidirectional flow, including backflow, of fluid in a conduit. The system utilizes a structural mechanism to create a pressure differential in the conduit. Pressure sensors are positioned upstream from the mechanism, at the mechanism, and downstream from the mechanism. Data from the pressure sensors are transmitted to a microprocessor or computer, and pressure differential detected between the pressure sensors is then used to calculate the backflow. Control signals may then be generated by the microprocessor or computer to shut off valves located in the conduit, upon the occurrence of backflow, or to control flow, total material dispersed, etc. in the conduit.
System and method for bidirectional flow and controlling fluid flow in a conduit
Ortiz, M.G.
1999-03-23
A system for measuring bidirectional flow, including backflow, of fluid in a conduit is disclosed. The system utilizes a structural mechanism to create a pressure differential in the conduit. Pressure sensors are positioned upstream from the mechanism, at the mechanism, and downstream from the mechanism. Data from the pressure sensors are transmitted to a microprocessor or computer, and pressure differential detected between the pressure sensors is then used to calculate the backflow. Control signals may then be generated by the microprocessor or computer to shut off valves located in the conduit, upon the occurrence of backflow, or to control flow, total material dispersed, etc. in the conduit. 3 figs.
Adato, Michelle; Roopnaraine, Terry; Becker, Elisabeth
2011-06-01
Conditional cash transfer programs provide cash grants to poor households conditional on their participation in primary health care services. While significant impacts have been demonstrated quantitatively, little attention is paid to why CCTs have these observed impacts, and as importantly- why impacts are not greater than they are. This article draws on qualitative research from four countries over a ten year period (1999-2009) to provide insights into why expected health and nutrition impacts do and do not occur. In Nicaragua, El Salvador, and Turkey, ethnographic methods were used, involving between 87 and 120 households per country, and in Mexico, focus groups were conducted with 230 people. Key informant interviews were conducted with health care providers in all countries. While CCTs operate primarily on the assumption that a cash incentive will produce behaviour change, we found multiple sociocultural and structural influences on health care decisions that compete with cash. These include beliefs around traditional and modern biomedical practices, sociocultural norms, gender relations, and the quotidian experience of poverty in many dimensions. We conclude that impacts can be increased through a better understanding of multiple contextual influences on health care decisions, and greater attention to the health education components and complementary interventions. PMID:21122965
Similar and Yet So Different: Cash-for-Care in Six European Countries’ Long-Term Care Policies
Da Roit, Barbara; Le Bihan, Blanche
2010-01-01
Context: In response to increasing care needs, the reform or development of long-term care (LTC) systems has become a prominent policy issue in all European countries. Cash-for-care schemes—allowances instead of services provided to dependents—represent a key policy aimed at ensuring choice, fostering family care, developing care markets, and containing costs. Methods: A detailed analysis of policy documents and regulations, together with a systematic review of existing studies, was used to investigate the differences among six European countries (Austria, France, Germany, Italy, the Netherlands, and Sweden). The rationale and evolution of their various cash-for-care schemes within the framework of their LTC systems also were explored. Findings: While most of the literature present cash-for-care schemes as a common trend in the reforms that began in the 1990s and often treat them separately from the overarching LTC policies, this article argues that the policy context, timing, and specific regulation of the new schemes have created different visions of care and care work that in turn have given rise to distinct LTC configurations. Conclusions: A new typology of long-term care configurations is proposed based on the inclusiveness of the system, the role of cash-for-care schemes and their specific regulations, as well as the views of informal care and the care work that they require. PMID:20860573
NASA Technical Reports Server (NTRS)
Schmucker, R. H.
1983-01-01
Methods aimed at reduction of overexpansion and side load resulting from asymmetric flow separation for rocket nozzles with a high opening ratio are described. The methods employ additional measures for nozzles with a fixed opening ratio. The flow separation can be controlled by several types of nozzle inserts, the properties of which are discussed. Side loads and overexpansion can be reduced by adapting the shape of the nozzle and taking other additional measures for controlled separation of the boundary layer, such as trip wires.
Expiratory flow limitation definition, mechanisms, methods, and significance.
Tantucci, Claudio
2013-01-01
When expiratory flow is maximal during tidal breathing and cannot be increased unless operative lung volumes move towards total lung capacity, tidal expiratory flow limitation (EFL) is said to occur. EFL represents a severe mechanical constraint caused by different mechanisms and observed in different conditions, but it is more relevant in terms of prevalence and negative consequences in obstructive lung diseases and particularly in chronic obstructive pulmonary disease (COPD). Although in COPD patients EFL more commonly develops during exercise, in more advanced disorder it can be present at rest, before in supine position, and then in seated-sitting position. In any circumstances EFL predisposes to pulmonary dynamic hyperinflation and its unfavorable effects such as increased elastic work of breathing, inspiratory muscles dysfunction, and progressive neuroventilatory dissociation, leading to reduced exercise tolerance, marked breathlessness during effort, and severe chronic dyspnea. PMID:23606962
Methods Used in Game Development to Foster FLOW
NASA Technical Reports Server (NTRS)
Jeppsen, Isaac Ben
2010-01-01
Games designed for entertainment have a rich history of providing compelling experiences. From consoles to PCs, games have managed to present intuitive and effective interfaces for a wide range of game styles to successfully allow users to "walk-up-and-play". Once a user is hooked, successful games artfully present challenging experiences just within reach of a user's ability, weaving each task and achievement into a compelling and engaging experience. In this paper, engagement is discussed in terms of the psychological theory of Flow. I argue that engagement should be one of the primary goals when developing a serious game and I discuss the best practices and techniques that have emerged from traditional video game development which help foster the creation of engaging, high Flow experiences.
Method of producing monolithic ceramic cross-flow filter
Larsen, David A.; Bacchi, David P.; Connors, Timothy F.; Collins, III, Edwin L.
1998-01-01
Ceramic filter of various configuration have been used to filter particulates from hot gases exhausted from coal-fired systems. Prior ceramic cross-flow filters have been favored over other types, but those previously horn have been assemblies of parts somehow fastened together and consequently subject often to distortion or delamination on exposure hot gas in normal use. The present new monolithic, seamless, cross-flow ceramic filters, being of one-piece construction, are not prone to such failure. Further, these new products are made by novel casting process which involves the key steps of demolding the ceramic filter green body so that none of the fragile inner walls of the filter is cracked or broken.
Method of producing monolithic ceramic cross-flow filter
Larsen, D.A.; Bacchi, D.P.; Connors, T.F.; Collins, E.L. III
1998-02-10
Ceramic filter of various configuration have been used to filter particulates from hot gases exhausted from coal-fired systems. Prior ceramic cross-flow filters have been favored over other types, but those previously have been assemblies of parts somehow fastened together and consequently subject often to distortion or delamination on exposure hot gas in normal use. The present new monolithic, seamless, cross-flow ceramic filters, being of one-piece construction, are not prone to such failure. Further, these new products are made by a novel casting process which involves the key steps of demolding the ceramic filter green body so that none of the fragile inner walls of the filter is cracked or broken. 2 figs.
Expiratory Flow Limitation Definition, Mechanisms, Methods, and Significance
Tantucci, Claudio
2013-01-01
When expiratory flow is maximal during tidal breathing and cannot be increased unless operative lung volumes move towards total lung capacity, tidal expiratory flow limitation (EFL) is said to occur. EFL represents a severe mechanical constraint caused by different mechanisms and observed in different conditions, but it is more relevant in terms of prevalence and negative consequences in obstructive lung diseases and particularly in chronic obstructive pulmonary disease (COPD). Although in COPD patients EFL more commonly develops during exercise, in more advanced disorder it can be present at rest, before in supine position, and then in seated-sitting position. In any circumstances EFL predisposes to pulmonary dynamic hyperinflation and its unfavorable effects such as increased elastic work of breathing, inspiratory muscles dysfunction, and progressive neuroventilatory dissociation, leading to reduced exercise tolerance, marked breathlessness during effort, and severe chronic dyspnea. PMID:23606962
System and method measuring fluid flow in a conduit
Ortiz, M.G.; Kidd, T.G.
1999-05-18
A system is described for measuring fluid mass flow in a conduit in which there exists a pressure differential in the fluid between at least two spaced-apart locations in the conduit. The system includes a first pressure transducer disposed in the side of the conduit at a first location for measuring pressure of fluid at that location, a second or more pressure transducers disposed in the side of the conduit at a second location, for making multiple measurements of pressure of fluid in the conduit at that location, and a computer for computing the average pressure of the multiple measurements at the second location and for computing flow rate of fluid in the conduit from the pressure measurement by the first pressure transducer and from the average pressure calculation of the multiple measurements. 3 figs.
System and method measuring fluid flow in a conduit
Ortiz, Marcos German; Kidd, Terrel G.
1999-01-01
A system for measuring fluid mass flow in a conduit in which there exists a pressure differential in the fluid between at least two spaced-apart locations in the conduit. The system includes a first pressure transducer disposed in the side of the conduit at a first location for measuring pressure of fluid at that location, a second or more pressure transducers disposed in the side of the conduit at a second location, for making multiple measurements of pressure of fluid in the conduit at that location, and a computer for computing the average pressure of the multiple measurements at the second location and for computing flow rate of fluid in the conduit from the pressure measurement by the first pressure transducer and from the average pressure calculation of the multiple measurements.
Solution of Reactive Compressible Flows Using an Adaptive Wavelet Method
NASA Astrophysics Data System (ADS)
Zikoski, Zachary; Paolucci, Samuel; Powers, Joseph
2008-11-01
This work presents numerical simulations of reactive compressible flow, including detailed multicomponent transport, using an adaptive wavelet algorithm. The algorithm allows for dynamic grid adaptation which enhances our ability to fully resolve all physically relevant scales. The thermodynamic properties, equation of state, and multicomponent transport properties are provided by CHEMKIN and TRANSPORT libraries. Results for viscous detonation in a H2:O2:Ar mixture, and other problems in multiple dimensions, are included.
An unconditionally stable Runge-Kutta method for unsteady flows
NASA Technical Reports Server (NTRS)
Jorgenson, Philip C. E.; Chima, Rodrick V.
1989-01-01
A quasi-three-dimensional analysis was developed for unsteady rotor-stator interaction in turbomachinery. The analysis solves the unsteady Euler or thin-layer Navier-Stokes equations in a body-fitted coordinate system. It accounts for the effects of rotation, radius change, and stream surface thickness. The Baldwin-Lomax eddy viscosity model is used for turbulent flows. The equations are integrated in time using a four-stage Runge-Kutta scheme with a constant time step. Implicit residual smoothing was employed to accelerate the solution of the time accurate computations. The scheme is described and accuracy analyses are given. Results are shown for a supersonic through-flow fan designed for NASA Lewis. The rotor:stator blade ratio was taken as 1:1. Results are also shown for the first stage of the Space Shuttle Main Engine high pressure fuel turbopump. Here the blade ratio is 2:3. Implicit residual smoothing was used to increase the time step limit of the unsmoothed scheme by a factor of six with negligible differences in the unsteady results. It is felt that the implicitly smoothed Runge-Kutta scheme is easily competitive with implicit schemes for unsteady flows while retaining the simplicity of an explicit scheme.
An unconditionally stable Runge-Kutta method for unsteady flows
NASA Technical Reports Server (NTRS)
Jorgenson, Philip C. E.; Chima, Rodrick V.
1988-01-01
A quasi-three dimensional analysis was developed for unsteady rotor-stator interaction in turbomachinery. The analysis solves the unsteady Euler or thin-layer Navier-Stokes equations in a body fitted coordinate system. It accounts for the effects of rotation, radius change, and stream surface thickness. The Baldwin-Lomax eddy viscosity model is used for turbulent flows. The equations are integrated in time using a four stage Runge-Kutta scheme with a constant time step. Implicit residual smoothing was employed to accelerate the solution of the time accurate computations. The scheme is described and accuracy analyses are given. Results are shown for a supersonic through-flow fan designed for NASA Lewis. The rotor:stator blade ratio was taken as 1:1. Results are also shown for the first stage of the Space Shuttle Main Engine high pressure fuel turbopump. Here the blade ratio is 2:3. Implicit residual smoothing was used to increase the time step limit of the unsmoothed scheme by a factor of six with negligible differences in the unsteady results. It is felt that the implicitly smoothed Runge-Kutta scheme is easily competitive with implicit schemes for unsteady flows while retaining the simplicity of an explicit scheme.
Topology method for analyses of 3-D viscous flow structure in transonic turbomachinery
NASA Astrophysics Data System (ADS)
Guo, Yanhu; Wang, Baoguo; Shen, Mengyu
1997-12-01
A topology method is presented in this paper to reveal flow structure occurring inside turbomachinery, in which near wall flow structure is revealed by using wall limiting streamlines and space flow feature is revealed by using space streamlines and cross-section streamlines. As an example, a computational three-dimensional viscous flow field inside a transonic turbine cascade is studied. Through the analysis, the form and evolution of vortex system and the whole process of separation occurring within this cascade are revealed. The application of topology method for analyze flow structure inside turbomachinery is very important for understanding flow features and mechanism of flow loss even for improving the design of turbomachinery and increasing its efficiency.
An Empirical Method for Fast Prediction of Rarefied Flow Field around a Vertical Plate
NASA Astrophysics Data System (ADS)
He, Tao; Wang, Jiang-Feng
2016-06-01
Numerical study is conducted to investigate the effects of free-stream Knudsen (Kn) number on rarefied flow field around a vertical plate employing an unstructured DSMC method, and an empirical method for fast prediction of flow-field structure at different Kn numbers in a given inflow velocity is proposed. First, the flow at a velocity 7500m/s is simulated using a perfect-gas model with free-stream Kn changing from 0.035 to 13.36. The flow-field characteristics in these cases with varying Kn numbers are analyzed and a linear-expansion phenomenon as a function of the square of Kn is discovered. An empirical method is proposed for fast flow-field prediction at different Kn based on the least-square-fitting method. Further, the effects of chemical reactions on flow field are investigated to verify the applicability of the empirical method in the real gas conditions. Three of the cases in perfect-gas flow are simulated again by introducing five-species air chemical module. The flow properties with and without chemical reactions are compared. In the end, the variation of chemical-reaction flow field as a function of Kn is analyzed and it is shown that the empirical method are also suitable when considering chemical reactions.
Flow instability of a centrifugal pump determined using the energy gradient method
NASA Astrophysics Data System (ADS)
Li, Yi; Dong, Wenlong; He, Zhaohui; Huang, Yuanmin; Jiang, Xiaojun
2015-02-01
The stability of the centrifugal pump has not been well revealed because of the complexity of internal flow. To analyze the flow characteristics of a centrifugal pump operating at low capacity, methods of numerical simulation and experimental research were adopted in this paper. Characteristics of the inner flow were obtained. Standard k-ɛ turbulence models were used to calculate the inner flow of the pump under off-design conditions. The distribution of the energy gradient function K was obtained by three-dimensional numerical simulation at different flow rates. The relative velocity component was acquired from the absolute velocity obtained in particle image velocimetry. By comparing with experimental results, it was found that flow instability occurs at the position of maximum K. The flow stability reduces with an increasing flow rate. The research results provide a theoretical basis for the optimization design of a centrifugal pump.
Kinetic theory based new upwind methods for inviscid compressible flows
NASA Technical Reports Server (NTRS)
Deshpande, S. M.
1986-01-01
Two new upwind methods called the Kinetic Numerical Method (KNM) and the Kinetic Flux Vector Splitting (KFVS) method for the solution of the Euler equations have been presented. Both of these methods can be regarded as some suitable moments of an upwind scheme for the solution of the Boltzmann equation provided the distribution function is Maxwellian. This moment-method strategy leads to a unification of the Riemann approach and the pseudo-particle approach used earlier in the development of upwind methods for the Euler equations. A very important aspect of the moment-method strategy is that the new upwind methods satisfy the entropy condition because of the Boltzmann H-Theorem and suggest a possible way of extending the Total Variation Diminishing (TVD) principle within the framework of the H-Theorem. The ability of these methods in obtaining accurate wiggle-free solution is demonstrated by applying them to two test problems.
Tracking and Measurement of the Motion of Blood Cells Using Optical Flow Methods
Guo, Dongmin; Van de Ven, Anne L.; Zhou, Xiaobo
2014-01-01
The investigation of microcirculation is a critical task in biomedical and physiological research. In order to monitor human’s condition and develop effective therapies of some diseases, the microcirculation information, such as flow velocity and vessel density, must be evaluated in a noninvasive manner. As one of the tasks of microcirculation investigation, automatic blood cell tracking presents an effective approach to estimate blood flow velocity. Currently, the most common method for blood cell tracking is based on spatiotemporal image analysis, which has lots of limitations, such as the diameter of microvesssels cannot be too larger than blood cells or tracers, cells or tracers should have fixed velocity, and it requires the image with high qualification. In this paper, we propose an optical flow method for automatic cell tracking. The key algorithm of the method is to align an image to its neighbors in a large image collection consisting of a variety of scenes. Considering the method cannot solve the problems in all cases of cell movement, another optical flow method, SIFT (Scale Invariant Feature Transform) flow, is also presented. The experimental results show that both methods can track the cells accurately. Optical flow is specially robust to the case where the velocity of cell is unstable, while SIFT flow works well when there are large displacement of cell between two adjacent frames. Our proposed methods outperform other methods when doing in vivo cell tracking, which can be used to estimate the blood flow directly and help to evaluate other parameters in microcirculation. PMID:24058034
Method and apparatus to measure vapor pressure in a flow system
Grossman, Mark W.; Biblarz, Oscar
1991-01-01
The present invention is directed to a method for determining, by a condensation method, the vapor pressure of a material with a known vapor pressure versus temperature characteristic, in a flow system particularly in a mercury isotope enrichment process.
Method of characteristics for three-dimensional axially symmetrical supersonic flows.
NASA Technical Reports Server (NTRS)
Sauer, R
1947-01-01
An approximation method for three-dimensional axially symmetrical supersonic flows is developed; it is based on the characteristics theory (represented partly graphically, partly analytically). Thereafter this method is applied to the construction of rotationally symmetrical nozzles. (author)
A Method to Evaluate Groundwater flow system under the Seabed
NASA Astrophysics Data System (ADS)
Kohara, N.; Marui, A.
2011-12-01
/ fresh water interface (position of the submarine groundwater discharge) may appear on the seafloor. Moreover, neither the salinity concentration nor the groundwater age depends on depth. It is thought that it is because that the groundwater forms the complex flow situation through the change in a long-term groundwater flow system. The technology to understand the coastal groundwater flow consists of remote sensing, geographical features analysis, surface of the earth investigation, geophysical exploration, drilling survey, and indoor examination and the measurement. Integration of each technology is needed to interpret groundwater flow system because the one is to catch the local groundwater flow in the time series and another one is to catch the long-term and regional groundwater flow in the general situation. The purpose of this study is to review the previous research of coastal groundwater flow, and to integrate an applicable evaluation approach to understand this mechanism. In this presentation, the review of the research and case study using numerical simulation are introduced.
Computing Cash Discounts. Student's Manual and Instructor's Manual.
ERIC Educational Resources Information Center
Hamer, Jean
Supporting performance objective 51 of the V-TECS (Vocational-Technical Education Consortium of States) Secretarial Catalog, both a set of student materials and an instructor's manual on computing cash discounts are included in this packet. (The packet is the fourth in a set of nine on performing computational clerical activities--CE 016 951-959.)…
31 CFR 206.6 - Cash management planning and review.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 31 Money and Finance: Treasury 2 2010-07-01 2010-07-01 false Cash management planning and review. 206.6 Section 206.6 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) FISCAL SERVICE, DEPARTMENT OF THE TREASURY FINANCIAL MANAGEMENT SERVICE MANAGEMENT OF FEDERAL AGENCY RECEIPTS, DISBURSEMENTS, AND OPERATION OF...
45 CFR 400.52 - Emergency cash assistance to refugees.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 45 Public Welfare 2 2011-10-01 2011-10-01 false Emergency cash assistance to refugees. 400.52 Section 400.52 Public Welfare Regulations Relating to Public Welfare OFFICE OF REFUGEE RESETTLEMENT, ADMINISTRATION FOR CHILDREN AND FAMILIES, DEPARTMENT OF HEALTH AND HUMAN SERVICES REFUGEE RESETTLEMENT...
45 CFR 400.52 - Emergency cash assistance to refugees.
Code of Federal Regulations, 2014 CFR
2014-10-01
... 45 Public Welfare 2 2014-10-01 2012-10-01 true Emergency cash assistance to refugees. 400.52 Section 400.52 Public Welfare Regulations Relating to Public Welfare OFFICE OF REFUGEE RESETTLEMENT, ADMINISTRATION FOR CHILDREN AND FAMILIES, DEPARTMENT OF HEALTH AND HUMAN SERVICES REFUGEE RESETTLEMENT...
20 CFR 340.5 - Recovery by cash payment.
Code of Federal Regulations, 2010 CFR
2010-04-01
... amounts recoverable be immediately and fully repaid in cash and any debtor shall have the absolute right to repay such amount recoverable in this manner. However if the debtor is financially unable to pay the indebtedness in a lump sum, payment may be accepted in regular installments. The amount...
18 CFR 367.1360 - Account 136, Temporary cash investments.
Code of Federal Regulations, 2010 CFR
2010-04-01
... cash investments. 367.1360 Section 367.1360 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY REGULATIONS UNDER THE PUBLIC UTILITY HOLDING COMPANY ACT OF 2005... GAS ACT Balance Sheet Chart of Accounts Current and Accrued Assets § 367.1360 Account 136,...
Conditional Cash Penalties in Education: Evidence from the Learnfare Experiment
ERIC Educational Resources Information Center
Dee, Thomas S.
2011-01-01
Wisconsin's influential Learnfare initiative is a conditional cash "penalty" program that sanctions a family's welfare grant when covered teens fail to meet school attendance targets. In the presence of reference-dependent preferences, Learnfare provides uniquely powerful financial incentives for student performance. However, a 10-county…
42 CFR 35.66 - Expenditure of cash contributions.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 42 Public Health 1 2012-10-01 2012-10-01 false Expenditure of cash contributions. 35.66 Section 35.66 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES MEDICAL CARE AND EXAMINATIONS HOSPITAL AND STATION MANAGEMENT Contributions for the Benefit of Patients § 35.66 Expenditure...
42 CFR 35.66 - Expenditure of cash contributions.
Code of Federal Regulations, 2013 CFR
2013-10-01
... 42 Public Health 1 2013-10-01 2013-10-01 false Expenditure of cash contributions. 35.66 Section 35.66 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES MEDICAL CARE AND EXAMINATIONS HOSPITAL AND STATION MANAGEMENT Contributions for the Benefit of Patients § 35.66 Expenditure...
42 CFR 35.66 - Expenditure of cash contributions.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 42 Public Health 1 2011-10-01 2011-10-01 false Expenditure of cash contributions. 35.66 Section 35.66 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES MEDICAL CARE AND EXAMINATIONS HOSPITAL AND STATION MANAGEMENT Contributions for the Benefit of Patients § 35.66 Expenditure...
Code of Federal Regulations, 2013 CFR
2013-01-01
... 7 Agriculture 4 2013-01-01 2013-01-01 false SSI cash-out. 273.20 Section 273.20 Agriculture Regulations of the Department of Agriculture (Continued) FOOD AND NUTRITION SERVICE, DEPARTMENT OF AGRICULTURE FOOD STAMP AND FOOD DISTRIBUTION PROGRAM CERTIFICATION OF ELIGIBLE HOUSEHOLDS Program...
18 CFR 367.1360 - Account 136, Temporary cash investments.
Code of Federal Regulations, 2011 CFR
2011-04-01
... cash investments. 367.1360 Section 367.1360 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY REGULATIONS UNDER THE PUBLIC UTILITY HOLDING COMPANY ACT OF 2005... GAS ACT Balance Sheet Chart of Accounts Current and Accrued Assets § 367.1360 Account 136,...
18 CFR 367.1360 - Account 136, Temporary cash investments.
Code of Federal Regulations, 2013 CFR
2013-04-01
... cash investments. 367.1360 Section 367.1360 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY REGULATIONS UNDER THE PUBLIC UTILITY HOLDING COMPANY ACT OF 2005... GAS ACT Balance Sheet Chart of Accounts Current and Accrued Assets § 367.1360 Account 136,...
18 CFR 367.1360 - Account 136, Temporary cash investments.
Code of Federal Regulations, 2012 CFR
2012-04-01
... cash investments. 367.1360 Section 367.1360 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY REGULATIONS UNDER THE PUBLIC UTILITY HOLDING COMPANY ACT OF 2005... GAS ACT Balance Sheet Chart of Accounts Current and Accrued Assets § 367.1360 Account 136,...
45 CFR 400.52 - Emergency cash assistance to refugees.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 45 Public Welfare 2 2010-10-01 2010-10-01 false Emergency cash assistance to refugees. 400.52 Section 400.52 Public Welfare Regulations Relating to Public Welfare OFFICE OF REFUGEE RESETTLEMENT, ADMINISTRATION FOR CHILDREN AND FAMILIES, DEPARTMENT OF HEALTH AND HUMAN SERVICES REFUGEE RESETTLEMENT...
45 CFR 400.52 - Emergency cash assistance to refugees.
Code of Federal Regulations, 2013 CFR
2013-10-01
... 45 Public Welfare 2 2013-10-01 2012-10-01 true Emergency cash assistance to refugees. 400.52 Section 400.52 Public Welfare Regulations Relating to Public Welfare OFFICE OF REFUGEE RESETTLEMENT, ADMINISTRATION FOR CHILDREN AND FAMILIES, DEPARTMENT OF HEALTH AND HUMAN SERVICES REFUGEE RESETTLEMENT...
45 CFR 400.52 - Emergency cash assistance to refugees.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 45 Public Welfare 2 2012-10-01 2012-10-01 false Emergency cash assistance to refugees. 400.52 Section 400.52 Public Welfare Regulations Relating to Public Welfare OFFICE OF REFUGEE RESETTLEMENT, ADMINISTRATION FOR CHILDREN AND FAMILIES, DEPARTMENT OF HEALTH AND HUMAN SERVICES REFUGEE RESETTLEMENT...
Financial Management: Cash Management Practices in Florida Community Colleges.
ERIC Educational Resources Information Center
Spiwak, Rand S.
A study was conducted to identify those variables appearing to affect cash management practices in Florida community colleges, and recommend prescriptive measures concerning these practices. The study methodology included informal discussions with the chief fiscal officers of each Florida community college and appropriate state board staff,…
Code of Federal Regulations, 2012 CFR
2012-01-01
... 7 Agriculture 4 2012-01-01 2012-01-01 false SSI cash-out. 273.20 Section 273.20 Agriculture Regulations of the Department of Agriculture (Continued) FOOD AND NUTRITION SERVICE, DEPARTMENT OF AGRICULTURE... benefits. The Secretary of the Department of Health and Human Services has determined that the SSI...
Multidimensional Targeting: Identifying Beneficiaries of Conditional Cash Transfer Programs
ERIC Educational Resources Information Center
Azevedo, Viviane; Robles, Marcos
2013-01-01
Conditional cash transfer programs (CCTs) have two main objectives: reducing poverty and increasing the human capital of children. To reach these objectives, transfers are given to poor households conditioned on investments in their children's education, health, and nutrition. Targeting mechanisms used by CCTs have been generally successful in…
Code of Federal Regulations, 2011 CFR
2011-01-01
... 7 Agriculture 4 2011-01-01 2011-01-01 false SSI cash-out. 273.20 Section 273.20 Agriculture Regulations of the Department of Agriculture (Continued) FOOD AND NUTRITION SERVICE, DEPARTMENT OF AGRICULTURE... benefits. The Secretary of the Department of Health and Human Services has determined that the SSI...