The Direct Method of Cash Flows.
ERIC Educational Resources Information Center
Bosserman, David C.; Fischer, Mary
2000-01-01
Explains to college/university business officers how to comply with Governmental Accounting Standards Board Statements Nos. 34, 35, and 9, which require the direct method of presenting cash flows from operating activities and reconciliation of operating cash flows to operating income by fiscal year 2001. Institutions are urged to begin immediately…
The Direct Method of Cash Flows.
ERIC Educational Resources Information Center
Bosserman, David C.; Fischer, Mary
2000-01-01
Explains to college/university business officers how to comply with Governmental Accounting Standards Board Statements Nos. 34, 35, and 9, which require the direct method of presenting cash flows from operating activities and reconciliation of operating cash flows to operating income by fiscal year 2001. Institutions are urged to begin immediately…
Effective methods for cash flow analysis.
Sylvestre, J; Urbancic, F R
1994-07-01
This article discusses techniques that healthcare financial managers can use to interpret and evaluate information from the statement of cash flows for more effective financial decision-making. The use of these techniques as a basis for systematically planning and controlling cash flows has the potential to benefit all healthcare organizations.
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.
Kamenetzky, S A
1993-06-01
In the face of decreasing reimbursement and increasing expenses, careful cash flow management has assumed an increasingly important role in developing and maintaining a successful ophthalmology practice. Funds must be collected as promptly and efficiently as possible, and retained and invested until needed by the practice to pay expenses. Office collection techniques and suggestions for dealing with third-party payers are presented. Managed care contracting and the inherent risks involved are discussed. Advice on accounts payable management is provided, and suggestions for investment of idle funds are outlined. This information should allow the formulation of a practical plan to maximize profitability in each ophthalmology practice.
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.
Russell, Philip J
2007-01-01
Medical imaging centers are an increasingly integral part of the medical services landscape in America. There are many instances in which owners and potential buyers of these enterprises want to ascertain the value of the businesses. There is an industry of professionals who provide expert valuation services for many types of businesses using various recognized alternative methods, some of which are more appropriate than others when valuing an imaging center. The federal government has prescribed parameters for all valuations if they lead to transactions in which fair market value is mandated, and it also expects transactions to adhere to more generalized laws relating to entities that provide services to Medicare patients. Radiologists who own, or who are contemplating ownership of, imaging center operations need to understand the principles of valuation, specifically the factors that are involved in a discounted cash flow determination of fair market value.
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…
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…
The Cash Flow Budget. Part II--Implementation
ERIC Educational Resources Information Center
Gehm, Rudy
1978-01-01
An "aged accounts payable" (A/P) summary and a cash disbursements journal are advocated as management measures useful in monitoring the cash flow in a college store. Methods for maintaining the A/P summary and for updating the journal are illustrated. (LBH)
The Cash Flow Budget. Part II--Implementation
ERIC Educational Resources Information Center
Gehm, Rudy
1978-01-01
An "aged accounts payable" (A/P) summary and a cash disbursements journal are advocated as management measures useful in monitoring the cash flow in a college store. Methods for maintaining the A/P summary and for updating the journal are illustrated. (LBH)
Get the Most from Your Cash Flow.
ERIC Educational Resources Information Center
Bauer, Richard I.
1995-01-01
Provides guidelines for overseeing a school district's cash-flow management program: (1) receipts into cash; (2) types of float; (3) concentration account or controlled-disbursement account; (4) bank-account analysis; and (5) safety. One figure is included. (LMI)
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)
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)
Get the Most from Your Cash Flow.
ERIC Educational Resources Information Center
Bauer, Richard I.
1995-01-01
Provides guidelines for overseeing a school district's cash-flow management program: (1) receipts into cash; (2) types of float; (3) concentration account or controlled-disbursement account; (4) bank-account analysis; and (5) safety. One figure is included. (LMI)
Business office innovations improve hospital cash flow.
Anderson, H J
1991-04-05
The business office accounts for a major portion of hospitals' administrative and financial expenses. And, in the current shaky economic climate, hospitals faced with slowdowns and cutbacks in payments from a variety of sources are scrambling to come up with innovative ways to improve cash flow. "The hospital that has good cash flow will be the one able to survive," says George Arges, a senior policy analyst at the American Hospital Association's Division of Policy and Capital Finance in Chicago.
48 CFR 232.072-3 - Cash flow forecasts.
Code of Federal Regulations, 2010 CFR
2010-10-01
... problems. (c) Single or one-time cash flow forecasts are of limited forecasting power. As such, they should... by comparing a series of previous actual cash flows with the corresponding forecasts and...
48 CFR 232.072-3 - Cash flow forecasts.
Code of Federal Regulations, 2014 CFR
2014-10-01
... 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. (a) A contractor must be able to sustain a sufficient cash flow to perform the contract. When there is...
48 CFR 232.072-3 - Cash flow forecasts.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 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. (a) A contractor must be able to sustain a sufficient cash flow to perform the contract. When there is...
FASB 95--a tool for identifying cash flow problems.
Edwards, D E; Hauser, R C
1989-06-01
Increasing expenditures and longer collection periods for receivables are symptoms of the cash flow problem that many not-for-profit healthcare organizations face. The FASB 95 provisions for a cash flow statement could help many of these organizations deal with their cash flow crises. The statement allows managers to evaluate their institution's financial performance, providing timely information that may make the difference in the struggle to maintain an adequate cash position.
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)
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)
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…
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…
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 Model for Determining School District Cash Flow Needs.
ERIC Educational Resources Information Center
Dembowski, Frederick L.
This paper discusses a model to optimize cash management in school districts. A brief discussion of the cash flow pattern of school districts is followed by an analysis of the constraints faced by the school districts in their investment planning process. A linear programming model used to optimize net interest earnings on investments is developed…
A Model for Determining School District Cash Flow Needs.
ERIC Educational Resources Information Center
Dembowski, Frederick L.
This paper discusses a model to optimize cash management in school districts. A brief discussion of the cash flow pattern of school districts is followed by an analysis of the constraints faced by the school districts in their investment planning process. A linear programming model used to optimize net interest earnings on investments is developed…
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.
Cash Flow Statement Spreadsheet Modeling Case Using a Prototype System Development Process
ERIC Educational Resources Information Center
Davis, Jefferson T.
2015-01-01
U.S. GAAP and IFRS standards both require a cash flow statement that presents operating, investing and financing net cash flows (FASB, FAS 95; 1987; IASB, IAS 7, 1992). Although students are exposed to the cash flow statement in beginning accounting courses and then study the cash flow statement in more depth in intermediate accounting classes,…
Use DCF to save energy. [Discounted Cash Flow (DCF) program
Doane, R.C.
1982-07-01
The Discounted Cash Flow (DCF) program is written for the TI-59 programmable calculator, and a profitability analysis can help the process engineer decide among various alternatives in an energy conservation project. The objective of the analysis is to determine the following parameters: discounted cash flow rate of return (also called earning power), present value profit (at any specified cost of capital), present value profit as a percent of the capital investment, and the payback period (undiscounted).
Selling accounts receivable can improve cash flow.
Spiegel, M
1989-09-01
New financing programs especially geared to accounts receivable allow healthcare organizations to convert these assets into cash literally overnight and at costs below the prime interest rate. Certain pooled versions of the financing strategy include non-recourse features that guard against sharing bad debts among the participants. These pooled programs generally allow hospitals to continue managing and billing their own accounts.
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…
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…
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.
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.
Analysis of cash flow in academic medical centers in the United States.
McCue, Michael J; Thompson, Jon M
2011-09-01
To examine cash flow margins in academic medical centers (AMCs; i.e., teaching hospitals) in an effort both to determine any significant differences in a set of operational and financial factors known to influence cash flow for high- and low-cash-flow AMCs and to discuss how these findings affect AMC operations. The authors sampled the Medicare cost report data of 103 AMCs for fiscal years 2005, 2006, and 2007, and then they applied the t test to test for significant mean differences between the two cash flow groups across operational and financial variables (e.g., case mix, operating margin). Compared with low-cash-flow AMCs, high-cash-flow AMCs were larger-bed-size facilities, treated cases of greater complexity, generated higher net patient revenue per adjusted discharge, served a significantly lower percentage of Medicaid patients, had significantly higher average operating profit margins and cash flow margin ratios, possessed a higher number of days of cash on hand, and collected their receivables more quickly. Study findings imply that high-cash-flow AMCs were earning higher cash flow returns than low-cash-flow AMCs, which may be because high-cash-flow AMCs generate higher patient revenues while serving fewer lower-paying Medicaid patients.
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…
Good cash flow = come in fast, go out slow!
Garvey, Sherill
2002-07-01
The formula for successful cash management in home care is a simple one: The agency must bring cash in as quickly as possible, while keeping expenditures at as low and slow a pace as possible. However, while the formula may be simple, success may be elusive unless agency administrators have a well-thought-out plan to handle cash management.
ChargeOut! : discounted cash flow compared with traditional machine-rate analysis
Ted Bilek
2008-01-01
ChargeOut!, a discounted cash-flow methodology in spreadsheet format for analyzing machine costs, is compared with traditional machine-rate methodologies. Four machine-rate models are compared and a common data set representative of logging skiddersâ costs is used to illustrate the differences between ChargeOut! and the machine-rate methods. The study found that the...
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.
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.
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'…
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'…
Positive cash flow financing in the institutional sector: Final report
Not Available
1986-01-01
The economics of energy management has prompted a surge of private investment in institutional energy conservation efforts. Purpose of the Positive Cash Flow Financing in the Institutional sector project is to establish some management criteria for internal assessment of relevant conditions for energy financing and to aid institutional administrators in selecting the best financial options available. The project's research design included the selection of three sites and an assessment of energy efficiency financing conditions in three institutions at each site and at the state level. The analysis examined the financial and governance structure, energy cost and consumption, replication potential, opportunities for alternative financing, and the potential for a community-wide cooperative effort. Morgantown, West Virginia, was selected as the primary research site and the developmental work was conducted at West Virginia University (WVU). The City of Morgantown and the Monongalia County Board of Education served as sites to assess the replication potential. The verification sites were Dearborn, Michigan, and San Angelo, Texas, where the local governments, school systems, a college, and a hospital were studied.
Something for Nothing: Cash Flow as a Contract Incentive
2016-03-01
Defense AT&L: March-April 2016 16 Something for Nothing “Cash Flow” as a Contract Incentive John Pritchard n John Krieger Pritchard and...negligible resources are required to implement the incentive, this is the closest the government ever will come to getting something for nothing . The
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…
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, 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.
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.
Financing and cash flow management for the medical group practice.
Bert, Andrew J
2008-01-01
The expansion of a medical group practice and the addition of ancillary services require a substantial cash outlay. Obtaining proper financing to complete a successful expansion is a process that takes time, and there are critical steps that must be followed. The group's business objectives must be presented properly by developing a business plan detailing the practice and goals associated with the desired expansion. This article discusses some of the key elements that are essential in creating an overall effective business plan for the group medical practice.
Improving cash flow in a down economy. How HIM can help reduce denials.
Dunn, Rose
2009-03-01
Maybe HIM professionals can't ease tight credit or reduce bad debt, but they can make sure their organizations get full, correct reimbursement on the first submission. HIM professionals help improve cash flow by contributing to revenue cycle management n these tough economic times-when increases in bad
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.
ERIC Educational Resources Information Center
Matthews, Kenneth M.
1976-01-01
Discusses formulas for planning school district investment and borrowing strategies based on a district's predicted cash flow and presents a sample investment/borrowing schedule developed from hypothetical cash-flow data. (JG)
ERIC Educational Resources Information Center
Matthews, Kenneth M.
1976-01-01
Discusses formulas for planning school district investment and borrowing strategies based on a district's predicted cash flow and presents a sample investment/borrowing schedule developed from hypothetical cash-flow data. (JG)
JEFI: a cash flow analysis program (Version 3.0 for Windows). [Computer program].
Bruce Hansen; Jeff Palmer
1998-01-01
JEFFI/3 is a Windows-version of JEFFI/2. The differences between the two versions are the new interface, an investment term of 1 to 30 years (instead of 4 to 30), and a rich set of detailed online help documents. JEFFI/3 still retains a number of unique features of JEFFII2 related to treatment of the final year cash flows, depreciation, working capital, and derivation...
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.
McCue, Michael J
2007-01-01
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. This study aims to gain insight regarding the driving factors behind the high cash flow performance of large rural for-profit hospitals. Using 3 annual periods of Centers for Medicare and Medicaid cost report data with the last fiscal year ending between September 30, 2002, and August 30, 2003, the study found a cash flow margin of 21.5% for the large rural for-profit hospitals. All these facilities were owned by hospital management companies. To assess their underlying market, operational, and mission factors, these hospitals were compared to a similar comparison group of large rural nonprofit hospitals that are system owned and have positive cash flows. Using logistic regression analysis, the study found lower operating expense per adjusted discharge and salary expense as a percentage of total operating expense among large rural for-profit, system-owned hospitals with positive cash flows relative to nonprofits with similar traits. Overall, the findings of this study reflect how these for-profit hospitals, which are owned by hospital management companies, focus on controlling their labor costs as well as operating costs per discharge in order to achieve a greater positive cash flow position.
NASA Astrophysics Data System (ADS)
Carlowicz, Michael
After conducting a survey of the state of the 55,000 water systems in the United States, the Environmental Protection Agency has found that communities need $12.1 billion in immediate funding to protect the nation's drinking water supplies and to meet minimum health-based standards. Required by the 1996 Safe Drinking Water Act to assess the needed capital improvements to drinking-water supplies, EPA also estimated that $138.4 billion will be needed over the next 20 years to replace or upgrade the nation's eroding water infrastructure.
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.
CASH: a constructing comprehensive splice site method for detecting alternative splicing events.
Wu, Wenwu; Zong, Jie; Wei, Ning; Cheng, Jian; Zhou, Xuexia; Cheng, Yuanming; Chen, Dai; Guo, Qinghua; Zhang, Bo; Feng, Ying
2017-04-06
RNA-sequencing (RNA-seq) can generate millions of reads to provide clues for analyzing novel or abnormal alternative splicing (AS) events in cells. However, current methods for exploring AS events are still far from being satisfactory. Here, we present Comprehensive AS Hunting (CASH), which constructs comprehensive splice sites including known and novel AS sites in cells, and identifies differentially AS events between cells. We illuminated the versatility of CASH on RNA-seq data from a wide range of species and also on simulated in silico data, validated the advantages of CASH over other AS predictors and exhibited novel differentially AS events. Moreover, we used CASH to identify SRSF10-regulated AS events and investigated the evolution of SRSF10-regulated splicing. The results showed that SRSF10-regulated splicing events are highly evolvable from chickens, mice to humans. However, SRSF10-regulated splicing model was observed to be immutable, in which SRSF10 binding to cassette exon promotes exon inclusion while binding to downstream exon induces exon skipping. Altogether, CASH can significantly improve the detection of AS events and facilitate the study of AS regulation and function in cells; the SRSF10 data first demonstrate a flexibility of SRSF10 with their regulated splicing events but an immutability of SRSF10-regulated splicing model to produce opposite AS outcomes in vertebrates. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
Understanding the tools for managing cash.
Pelfrey, S
1990-10-01
An institution's survival in the 1990s depends on its ability to generate enough cash to meet its needs. The author discusses two accounting tools, the cash budget and the statement of cash flows, that help monitor and control cash flows. By understanding the nature and impact of each report, nurse administrators can help safeguard one of their institution's scarcest resources: cash.
Alternative Methods in the Evaluation of School District Cash Management Programs.
ERIC Educational Resources Information Center
Dembowski, Frederick L.
1980-01-01
Empirically evaluates three measures of effectiveness of school district cash management: the rate of return method in common use and two new measures--efficiency rating and Net Present Value (NPV). The NPV approach allows examination of efficiency and provides a framework for evaluating other areas of educational policy. (Author/IRT)
Alternative Methods in the Evaluation of School District Cash Management Programs.
ERIC Educational Resources Information Center
Dembowski, Frederick L.
1980-01-01
Empirically evaluates three measures of effectiveness of school district cash management: the rate of return method in common use and two new measures--efficiency rating and Net Present Value (NPV). The NPV approach allows examination of efficiency and provides a framework for evaluating other areas of educational policy. (Author/IRT)
NASA Astrophysics Data System (ADS)
Chen, Miawjane; Yan, Shangyao; Wang, Sin-Siang; Liu, Chiu-Lan
2015-02-01
An effective project schedule is essential for enterprises to increase their efficiency of project execution, to maximize profit, and to minimize wastage of resources. Heuristic algorithms have been developed to efficiently solve the complicated multi-mode resource-constrained project scheduling problem with discounted cash flows (MRCPSPDCF) that characterize real problems. However, the solutions obtained in past studies have been approximate and are difficult to evaluate in terms of optimality. In this study, a generalized network flow model, embedded in a time-precedence network, is proposed to formulate the MRCPSPDCF with the payment at activity completion times. Mathematically, the model is formulated as an integer network flow problem with side constraints, which can be efficiently solved for optimality, using existing mathematical programming software. To evaluate the model performance, numerical tests are performed. The test results indicate that the model could be a useful planning tool for project scheduling in the real world.
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
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…
E.M. (Ted) Bilek
2007-01-01
The model ChargeOut! was developed to determine charge-out rates or rates of return for machines and capital equipment. This paper introduces a costing methodology and applies it to a piece of capital equipment. Although designed for the forest industry, the methodology is readily transferable to other sectors. Based on discounted cash-flow analysis, ChargeOut!...
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
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…
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…
Failure to comply with CMS' new enrollment procedures could impact physicians' cash flow.
Duffy, Erin M
2007-01-01
The Centers for Medicare and Medicaid Services (CMS) has instituted big changes in its enrollment procedures that could have a major impact on physician groups that fail to comply with CMS' new requirements. First, tick ... tick ... tick ... time is quickly running out on the chance to obtain, and implement into the flow of your practice, a National Provider Identification number (NPI). The bad news is that the requirement to get an NPI is statutory, meaning it's not going to go away. Second, CMS revamped its Medicare provider enrollment processes in an attempt to reduce enrollment application processing delays. Unfortunately, rather than expedite the enrollment process, CMS' new regulations had the over-all effect of causing even more delays and backlogs in the enrollment process. Providers who do not have an NPI by the required deadline risk potential compliance penalties and payment delays. Therefore, not having an NPI or a Medicare Provider Number can have serious consequences on providers' ability to provide care as well as their bottom line (think cash flow!).
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.
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.
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.
31 CFR 206.6 - Cash management planning and review.
Code of Federal Regulations, 2010 CFR
2010-07-01
... cash flows in order to provide an overview of its cash management activities and to identify areas that... basis for identification of improvements and preparation of cash flow reports for submission to the... periodic cash management reviews, identifying improvements, and preparing cash flow reports. In...
41 CFR 301-51.101 - Which payment methods are considered the equivalent of cash?
Code of Federal Regulations, 2014 CFR
2014-07-01
... of cash for such purposes. (a) Personal credit cards; (b) Cash withdrawals obtained from an ATM using a Government contractor-issued individually billed travel card; and (c) Checks, both personal and...
41 CFR 301-51.101 - Which payment methods are considered the equivalent of cash?
Code of Federal Regulations, 2011 CFR
2011-07-01
... of cash for such purposes. (a) Personal credit cards; (b) Cash withdrawals obtained from an ATM using a Government contractor-issued individually billed travel card; and (c) Checks, both personal and...
41 CFR 301-51.101 - Which payment methods are considered the equivalent of cash?
Code of Federal Regulations, 2010 CFR
2010-07-01
... of cash for such purposes. (a) Personal credit cards; (b) Cash withdrawals obtained from an ATM using a Government contractor-issued individually billed travel card; and (c) Checks, both personal and...
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.
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.
41 CFR 301-51.101 - Which payment methods are considered the equivalent of cash?
Code of Federal Regulations, 2013 CFR
2013-07-01
... such purposes. (a) Personal credit cards; (b) Cash withdrawals obtained from an ATM using a Government contractor-issued individually billed travel card; and (c) Checks, both personal and travelers (including...
Optimal portfolio selection in a Lévy market with uncontrolled cash flow and only risky assets
NASA Astrophysics Data System (ADS)
Zeng, Yan; Li, Zhongfei; Wu, Huiling
2013-03-01
This article considers an investor who has an exogenous cash flow evolving according to a Lévy process and invests in a financial market consisting of only risky assets, whose prices are governed by exponential Lévy processes. Two continuous-time portfolio selection problems are studied for the investor. One is a benchmark problem, and the other is a mean-variance problem. The first problem is solved by adopting the stochastic dynamic programming approach, and the obtained results are extended to the second problem by employing the duality theory. Closed-form solutions of these two problems are derived. Some existing results are found to be special cases of our results.
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…
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.
ERIC Educational Resources Information Center
Nielsen, George A.; Johannisson, Eric E.
1989-01-01
The primary objective of a public cash management policy should include safety, liquidity, yield, and legality. Contains a cash management policy/procedure checklist, a test for cash managers, and a formula for calculating the rate of return. (MLF)
ERIC Educational Resources Information Center
Nielsen, George A.; Johannisson, Eric E.
1989-01-01
The primary objective of a public cash management policy should include safety, liquidity, yield, and legality. Contains a cash management policy/procedure checklist, a test for cash managers, and a formula for calculating the rate of return. (MLF)
Corporate cash management in health care: can we do better?
Coyne, J S
1987-09-01
Most healthcare financial managers are becoming increasingly aware of the importance of adequate cash flow over profit. Therefore, building and monitoring a corporate or centralized cash management system to improve cash flow could prove to be the crucial element in an institution's financial success or failure.
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…
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)
Cash planning in community mental health agencies.
Williams, E
1976-01-01
Community mental health agencies often receive funds from a number of different sources with varying restrictions. Cash planning can help them manage these funds properly and avoid serious problems. The use of a projected cash flow statement may even help produce additional income for them.
Barrett, Lee B; Hanks, Tom; Zubeldia, Kepa; Cramer, Richard
The deadlines are looming for compliance with the transaction and code set requirements set forth in the Health Insurance Portability and Accountability Act of 1996 (HIPAA). If your hospital filed for an extension in October 2002, you need to begin testing transactions by April 2003 and sending transactions by October 2003. But don't rely on your technology vendors to give you the ability to send compliant transactions. While vendors can provide the correct computer data format, they can't gather the correct information. If you can't send a compliant transaction, the Centers for Medicare and Medicaid Services could reject your claims, drying up a big percentage of your cash flow.
Code of Federal Regulations, 2010 CFR
2010-07-01
..., DEPARTMENT OF EDUCATION STUDENT ASSISTANCE GENERAL PROVISIONS Cash Management § 668.166 Excess cash. (a... than Federal Perkins Loan Program funds, that an institution does not disburse to students or parents... funds that an institution receives from the Secretary under the just-in-time payment method. (b) Excess...
Code of Federal Regulations, 2012 CFR
2012-07-01
..., DEPARTMENT OF EDUCATION STUDENT ASSISTANCE GENERAL PROVISIONS Cash Management § 668.166 Excess cash. (a... than Federal Perkins Loan Program funds, that an institution does not disburse to students or parents... funds that an institution receives from the Secretary under the just-in-time payment method. (b) Excess...
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.…
Cash streams: five powerful income streams to increase your net income.
Means, G B
1998-01-01
You can dramatically increase your profits by: Cash stream #1--extending credit and earning interest on the unpaid balance; Cash stream #2--doing all of the undone treatment in your practice; Cash stream #3--providing financing for everyone who deserves it; Cash stream #4--treating bigger cases; Cash stream #5--avoid treating deadbeats. There isn't anything I know of, which will jump start your practice as much as these five cash streams--more new patients, better case acceptance as well as increased cash flow. But you must get good at financing. You must have in place an organized, proven, financing system--just like the finance companies do.
Numerical methods for turbulent flow
NASA Technical Reports Server (NTRS)
Turner, James C., Jr.
1988-01-01
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.
Pless, Jacquelyn; Arent, Douglas J.; Logan, Jeffrey; Cochran, Jaquelin; Zinaman, Owen
2016-10-01
One energy policy objective in the United States is to promote the adoption of technologies that provide consumers with stable, secure, and clean energy. Recent work provides anecdotal evidence of natural gas (NG) and renewable electricity (RE) synergies in the power sector, however few studies quantify the value of investing in NG and RE systems together as complements. This paper uses discounted cash flow analysis and real options analysis to value hybrid NG-RE systems in distributed applications, focusing on residential and commercial projects assumed to be located in the states of New York and Texas. Technology performance and operational risk profiles are modeled at the hourly level to capture variable RE output and NG prices are modeled stochastically as geometric Ornstein-Uhlenbeck (OU) stochastic processes to capture NG price uncertainty. The findings consistently suggest that NG-RE hybrid distributed systems are more favorable investments in the applications studied relative to their single-technology alternatives when incentives for renewables are available. In some cases, NG-only systems are the favorable investments. Understanding the value of investing in NG-RE hybrid systems provides insights into one avenue towards reducing greenhouse gas emissions, given the important role of NG and RE in the power sector.
Cash budgeting: an underutilized resource management tool in not-for-profit health care entities.
Hauser, R C; Edwards, D E; Edwards, J T
1991-01-01
Cash budgeting is generally considered to be an important part of resource management in all businesses. However, respondents to a survey of not-for-profit health care entities revealed that some 40 percent of the participants do not currently prepare cash budgets. Where budgeting occurred, the cash forecasts covered various time frames, and distribution of the document was inconsistent. Most budgets presented cash receipts and disbursements according to operating, investing, and financing activities--a format consistent with the year-end cash flow statement. By routinely preparing monthly cash budgets, the not-for-profit health care entity can project cash inflow/outflow or position with anticipated cash insufficiencies and surpluses. The budget should be compared each month to actual results to evaluate performance. The magnitude and timing of cash flows is much too critical to be left to chance.
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 may...
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 may...
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 may...
28 CFR 345.72 - Cash bonus or cash award.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 28 Judicial Administration 2 2010-07-01 2010-07-01 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 may...
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 may...
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.
Projection Methods for Interdendritic Flows
Han, Q.; Sabau, A.S.; Viswanathan, S.
1999-02-28
In spite of recent advances in the mathematical modeling of fluid dynamics for materials processing applications, no significant advances have been made in the numerical discretization of these equations. In this work, the application of two-step projection methods for the numerical simulation of interdendritic flows is, discussed. Unlike previous methods, the methods presented here are constructed for the exact equations which are characterized by variable density and volumetric fraction of the liquid. The drag terms, which describe the momentum loss due to the flow around and through the dendrite structures, are treated implicitly. Numerical examples for shrinkage-induced flow during solidification of an AI-4.5% Cu alloy bar is used to illustrate the effectiveness of the proposed algorithm.
Babu, Sainath; Uppu, Sannihith N; Martin, Brittany; Agu, Ogad A; Uppu, Rao M
2015-01-01
We have developed a simple, reversed-phase high-performance liquid chromatography (RP-HPLC) method for the determination of bisphenol A (BPA) in thermal paper cash register receipts (CRs). The method is suitable for analysis of other types of bisphenols and it involves an overnight extraction of CRs with acetonitrile (AN) at 50 °C followed by the HPLC analysis on a Supelcosil LC18 column (150 × 4.6 mm, particle size: 5 μ) using 50% AN in water as the mobile phase (5 min, isocratic). The composition of AN in the mobile phase changed to 100% over a 10 min period (linear gradient) and then held at 100% AN for 10 min (isocratic). The flow rate was set at 1 mL/min (injection volume: 20 μL) and the eluent was monitored at 234 nm. The authentic BPA eluted with a retention time of 5.9 min and gave a linear detector response in the concentration range of 0.23-50 mg/L. BPA in the CR extracts also eluted with the same retention and had identical absorbance properties as the standard. When CR extracts were co-injected with authentic BPA, they were resolved as a single peak. Further, GC/MS/EI analysis of authentic BPA and the HPLC-purified CR extracts have identical ion chromatograms and fragmentation of the molecular ion (m/z = 228). We have analyzed 170 CRs collected from 62 different vendors including supermarkets, fast food restaurants, gas stations and banking outlets. Almost all cash receipts (n = 168) showed the presence of BPA in the concentration range of 0.45-4.26% (M ± SD, 1.54 ± 0.73%).
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.
Flow methods in chiral analysis.
Trojanowicz, Marek; Kaniewska, Marzena
2013-11-01
The methods used for the separation and analytical determination of individual isomers are based on interactions with substances exhibiting optical activity. The currently used methods for the analysis of optically active compounds are primarily high-performance separation methods, such as gas and liquid chromatography using chiral stationary phases or chiral selectors in the mobile phase, and highly efficient electromigration techniques, such as capillary electrophoresis using chiral selectors. Chemical sensors and biosensors may also be designed for the analysis of optically active compounds. As enantiomers of the same compound are characterised by almost identical physico-chemical properties, their differentiation/separation in one-step unit operation in steady-state or dynamic flow systems requires the use of highly effective chiral selectors. Examples of such determinations are reviewed in this paper, based on 105 references. The greatest successes for isomer determination involve immunochemical interactions, enantioselectivity of the enzymatic biocatalytic processes, and interactions with ion-channel receptors or molecularly imprinted polymers. Conducting such processes under dynamic flow conditions may significantly enhance the differences in the kinetics of such processes, leading to greater differences in the signals recorded for enantiomers. Such determinations in flow conditions are effectively performed using surface-plasmon resonance and piezoelectric detections, as well as using common spectroscopic and electrochemical detections.
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.
Improving cash flow through benchmarking.
Nelson, B
1994-09-01
Healthcare organizations can use two benchmarking techniques to improve their accounts receivable departments' performance: 1) studying the accounts receivable statistics of model healthcare organizations, and 2) visiting these model organizations in order to get a first-hand look at how they do business. Employing these two benchmarking techniques can help healthcare organizations reduce gross days revenue outstanding, bad debt, the length of time between the date a patient is discharged and the date a bill is mailed, the total percentage of receivables more than 90 days old, and general business office expenses related to collection.
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…
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…
Krishnan, Anand; Amarchand, Ritvik; Byass, Peter; Pandav, Chandrakant; Ng, Nawi
2014-01-31
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. 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. 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. 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 conditional cash transfer program.
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)
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.
45 CFR 302.20 - Separation of cash handling and accounting functions.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 45 Public Welfare 2 2010-10-01 2010-10-01 false Separation of cash handling and accounting..., DEPARTMENT OF HEALTH AND HUMAN SERVICES STATE PLAN REQUIREMENTS § 302.20 Separation of cash handling and... will maintain methods of administration designed to assure that persons responsible for handling cash...
Keep a Tight Fist on Petty Cash.
ERIC Educational Resources Information Center
Shannon, Thomas A., Jr.
1979-01-01
The listed guidelines for keeping track of petty cash in the schools are organized into three areas--making sure each school has an adequate method of collecting and banking money, adopting a simple and uniform bookkeeping system, and promoting fiscal responsibility. (IRT)
How much cash does your company need?
Passov, Richard
2003-11-01
In late 2001, the directors of Pfizer asked that very question. And with good reason. After its 2000 merger with rival Warner-Lambert, the New York-based pharmaceutical giant found itself sitting on a net cash position of $8 billion, which seemed extraordinarily conservative for a company whose products generated $30 billion in revenues. Most large companies with revenues that healthy would increase leverage, thereby unlocking tremendous value for shareholders. But knowledge-intensive companies like Pfizer, this author argues, are in a class apart. Because their largely intangible assets (like R&D) are highly volatile and cannot easily be valued, they are more vulnerable to financial distress than are firms with a preponderance of tangible assets. To insure against that risk, they need to maintain large positive cash balances. These companies' decisions to run large cash balances is one of the key reasons their shares sustain consistent premiums. Only by investing in their intangible assets can knowledge-based companies hope to preserve the value of those assets. A company that finds itself unable to do so because unfavorable market conditions reduce its operating cash flows will see its share price suffer almost as much as if it were to default on its debts. By the same token, with the right balance sheet, knowledge companies can profitably insure against the risk of failing to sustain value-added investments in difficult times. An optimal capital structure that calls for significant cash balances is certainly at odds with the results of a traditional capital structure analysis, the author demonstrates, but it explains the financial policies of many well-run companies, from Pfizer to Intel to ChevronTexaco.
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…
Fernald, Lia C. H.; Gertler, Paul J.; Neufeld, Lynnette M.
2009-01-01
Background Many governments around the world have implemented conditional cash transfer (CCT) programs with the goal of improving options for poor families through interventions in health, nutrition and education. Families enrolled in CCT programs receive cash in exchange for complying with “conditionalities” – preventive health requirements and nutrition supplementation, education and monitoring designed to improve health outcomes and promote positive behavior change. A great challenge in evaluating the effectiveness of CCT programs has been disaggregating the effects of the cash transfer component from that of the conditionalities. Methods In an intervention that began in 1998 in Mexico, low-income communities (n=506) were randomly assigned to be enrolled in a CCT program (Oportunidades, formerly Progresa) immediately or 18 months later. In 2003, children (n=3793), aged 24–72 months who had been enrolled in the program their entire lives, were assessed for a wide variety of outcomes. The analyses reported here separated out the association of the cash transfer component of Oportunidades with several outcomes in children from the program conditionalities, while controlling for a wide range of covariates including many measures of household socio-economic status. Findings An increase in the cash transfer to the household was associated with higher height-for-age z-score and hemoglobin concentration, lower prevalence of stunting, and lower prevalence of overweight. Children in families whose households received a greater quantity of cash also performed better on a scale of motor development (McCarthy Test of Children’s Abilities), three scales of cognitive development (sub-scales of the Woodcock-Muñoz, including working memory), and receptive language (Test de Vocabulario en Imágenes Peabody). Interpretation The results suggest that the cash transfer component of Oportunidades is associated with better outcomes in child health and development. PMID
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.
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
NASA Astrophysics Data System (ADS)
Seyler, F.; Bonnet, M.-P.; Calmant, S.; Cauhopé, M.; Cazenave, A.; Cochonneau, G.; Divol, J.; Do-Minh, K.; Frappart, F.; Gennero, M.-C.; Guyenne-Blin, K.; Huynh, F.; Leon, J. G.; Mangeas, M.; Mercier, F.; Rocquelain, GH.; Tocqueville, L.; Zanifé, O.-Z.
2006-07-01
CASH « Contribution of spatial altimetry to hydrology » aims at the definition of a global, standard, fast and long term access to a set of hydrological data concerning the greatest river basins in the world. The key questions to be answered are: what are the conditions for monitoring river water stages from altimetric radar data and how is it possible to combine altimetric data with other spatial sources or/and in-situ data in order to deliver useful parameters for hydrology community, both scientific and end users. The CASH project is ending mid-May of 2006 and there is yet a lot of tasks to be performed for altimetric heigths of continental water bodies becoming part of the scientific and end-users hydrologists day-to- day practice. The project has nethertheless delineated the way this use could be improved in a near future, and opened very interesting perspectives for ungauged or poorly gauged great basins in the world.
Cross flow electrofilter and method
Gidaspow, Dimitri; Lee, Chang H.; Wasan, Darsh T.
1981-01-01
A filter for clarifying carbonaceous liquids containing finely divided solid particles of, for instance, unreacted coal, ash and other solids discharged from a coal liquefaction process is presented. The filter includes two passageways separated by a porous filter medium. In one preferred embodiment the filter medium is of tubular shape to form the first passageway and is enclosed within an outer housing to form the second passageway within the annulus. An electrode disposed in the first passageway, for instance along the tube axis, is connected to a source of high voltage for establishing an electric field between the electrode and the filter medium. Slurry feed flows through the first passageway tangentially to the surfaces of the filter medium and the electrode. Particles from the feed slurry are attracted to the electrode within the first passageway to prevent plugging of the porous filter medium while carbonaceous liquid filters into the second passageway for withdrawal. Concentrated slurry is discharged from the first passageway at an end opposite to the feed slurry inlet. Means are also provided for the addition of diluent and a surfactant into the slurry to control relative permittivity and the electrophoretic mobility of the particles.
Techniques for cash management in scheduling manufacturing operations
NASA Astrophysics Data System (ADS)
Morady Gohareh, Mehdy; Shams Gharneh, Naser; Ghasemy Yaghin, Reza
2017-10-01
The objective in traditional scheduling is usually time based. Minimizing the makespan, total flow times, total tardi costs, etc. are instances of these objectives. In manufacturing, processing each job entails a cost paying and price receiving. Thus, the objective should include some notion of managing the flow of cash. We have defined two new objectives: maximization of average and minimum available cash. For single machine scheduling, it is demonstrated that scheduling jobs in decreasing order of profit ratios maximizes the former and improves productivity. Moreover, scheduling jobs in increasing order of costs and breaking ties in decreasing order of prices maximizes the latter and creates protection against financial instability.
Techniques for cash management in scheduling manufacturing operations
NASA Astrophysics Data System (ADS)
Morady Gohareh, Mehdy; Shams Gharneh, Naser; Ghasemy Yaghin, Reza
2016-10-01
The objective in traditional scheduling is usually time based. Minimizing the makespan, total flow times, total tardi costs, etc. are instances of these objectives. In manufacturing, processing each job entails a cost paying and price receiving. Thus, the objective should include some notion of managing the flow of cash. We have defined two new objectives: maximization of average and minimum available cash. For single machine scheduling, it is demonstrated that scheduling jobs in decreasing order of profit ratios maximizes the former and improves productivity. Moreover, scheduling jobs in increasing order of costs and breaking ties in decreasing order of prices maximizes the latter and creates protection against financial instability.
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.
Asymptotic methods for internal transonic flows
NASA Technical Reports Server (NTRS)
Adamson, T. C., Jr.; Messiter, A. F.
1989-01-01
For many internal transonic flows of practical interest, some of the relevant nondimensional parameters typically are small enough that a perturbation scheme can be expected to give a useful level of numerical accuracy. A variety of steady and unsteady transonic channel and cascade flows is studied with the help of systematic perturbation methods which take advantage of this fact. Asymptotic representations are constructed for small changes in channel cross-section area, small flow deflection angles, small differences between the flow velocity and the sound speed, small amplitudes of imposed oscillations, and small reduced frequencies. Inside a channel the flow is nearly one-dimensional except in thin regions immediately downstream of a shock wave, at the channel entrance and exit, and near the channel throat. A study of two-dimensional cascade flow is extended to include a description of three-dimensional compressor-rotor flow which leads to analytical results except in thin edge regions which require numerical solution. For unsteady flow the qualitative nature of the shock-wave motion in a channel depends strongly on the orders of magnitude of the frequency and amplitude of impressed wall oscillations or fluctuations in back pressure. One example of supersonic flow is considered, for a channel with length large compared to its width, including the effect of separation bubbles and the possibility of self-sustained oscillations. The effect of viscosity on a weak shock wave in a channel is discussed.
Small business, cash budgets and general practice.
Jackson, A R
1991-01-01
In practice management, general practice falls into the category of small business with all its attendant generic problems. Disciplined planning and good financial management are not often seen in small business. These are required if general practitioners are to continue (or return to) the provision of high quality medical services. An effective budget process, especially cash-flow budgeting, is the key to successful planning and financial management. Budgeting will bring Control, Co-ordination, and Credibility to your practice. It will enable you to set goals and to achieve them.
Finite element methods for high speed flows
NASA Technical Reports Server (NTRS)
Loehner, R.; Morgan, K.; Peraire, J.; Zienkiewicz, O. C.
1985-01-01
An explicit finite element based solution procedure for solving the equations of compressible viscous high speed flow is presented. The method uses domain splitting to advance the solution with different timesteps on different portions of the mesh. For steady inviscid flows, adaptive mesh refinement procedures are successfully employed to enhance the definition of discontinuities. Preliminary ideas on the application of adaptive mesh refinement to the solution of problems involving steady viscous flow are presented. Sample timings are given for the performance of the finite element code on modern supercomputers.
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.
Background field method in the gradient flow
NASA Astrophysics Data System (ADS)
Suzuki, Hiroshi
2015-10-01
In perturbative consideration of the Yang-Mills gradient flow, it is useful to introduce a gauge non-covariant term (“gauge-fixing term”) to the flow equation that gives rise to a Gaussian damping factor also for gauge degrees of freedom. In the present paper, we consider a modified form of the gauge-fixing term that manifestly preserves covariance under the background gauge transformation. It is shown that our gauge-fixing term does not affect gauge-invariant quantities as does the conventional gauge-fixing term. The formulation thus allows a background gauge covariant perturbative expansion of the flow equation that provides, in particular, a very efficient computational method of expansion coefficients in the small flow time expansion. The formulation can be generalized to systems containing fermions.
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.
Lattice Boltzmann methods for moving boundary flows
NASA Astrophysics Data System (ADS)
Inamuro, Takaji
2012-04-01
The lattice Boltzmann methods (LBMs) for moving boundary flows are presented. The LBM for two-phase fluid flows with the same density and the LBM combined with the immersed boundary method are described. In addition, the LBM on a moving multi-block grid is explained. Three numerical examples (a droplet moving in a constricted tube, the lift generation of a flapping wing and the sedimentation of an elliptical cylinder) are shown in order to demonstrate the applicability of the LBMs to moving boundary problems.
Cash management in health care systems.
Rivenson, H L; Wheeler, J R; Smith, D G; Reiter, K L
2000-01-01
Cash is one of the most precious assets held by health systems. This article presents results of discussions on cash management and investment policies at a dozen major not-for-profit health systems. Health system data indicate that cash holdings have increased dramatically since 1993, mostly due to investment earnings. Discussions with chief financial officers of these health systems reveal that cash holdings are significant, that decisions about cash balances are strategic, and that most systems aim to increase cash balances to levels that permit access to capital markets on more favorable terms.
Cash transportation vehicle routing and scheduling under stochastic travel times
NASA Astrophysics Data System (ADS)
Yan, Shangyao; Wang, Sin-Siang; Chang, Yu-Hsuan
2014-03-01
Stochastic disturbances occurring in real-world operations could have a significant influence on the planned routing and scheduling results of cash transportation vehicles. In this study, a time-space network flow technique is utilized to construct a cash transportation vehicle routing and scheduling model incorporating stochastic travel times. In addition, to help security carriers to formulate more flexible routes and schedules, a concept of the similarity of time and space for vehicle routing and scheduling is incorporated into the model. The test results show that the model could be useful for security carriers in actual practice.
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.
Advanced overset methods for vortex dominated flows
NASA Astrophysics Data System (ADS)
Foster, Norman F.
A newly implemented computational method of high-order accuracy is presented for the accurate calculation of unsteady vortical structures that may produce aeroacoustic sources, or affect downstream structural responses. The method involves prediction of the mean flow field by solving the Navier-Stokes equations (NSE) using a computational fluid dynamics (CFD) solver that employs high-order discretization on overlapping (overset) grid systems. The method dramatically reduces the artificial dissipation and dispersion of vortical flow features that would ordinarily be lost or degraded with the use of current methods. Complex domains are discretized using an overset grid strategy that allows for the use of multiple high quality structured meshes. The high-order method is developed and incorporated into a generalized overset grid assembly scheme, which allows high-order spatial accuracy of the NSE solutions to be maintained across overset grid boundaries. Comparisons are made to calculations that do not preserve high-order accuracy at overset boundaries, and insight is obtained into the effects and sensitivities of different treatments of overlapping boundaries. A nested block adaptive mesh refinement (AMR) method has also been developed, within the context of the overset paradigm. The method is shown to significantly improve accuracy for a given computational cell count by tracking dynamic vortical features using appropriate dynamic refinement and coarsening, and its implementation in the context of the high-order overset method is presented. The computational procedures presented herein are tested against analytic and canonical cases (slightly compressible, M ≤ 0.5, and incompressible mean flows) in order to characterize the accuracy of flow field calculations using high-order discretization and overset schemes across overlapping grid boundaries. The methods are also extended to far more complex systems including the transport of rotorcraft hub vorticity to
Computational Methods for Complex Flow Fields.
1986-06-28
James J. Riley Joel H . Ferziger "Turbulent Flow Simulation - Future Needs" Micha Wolfshtein " Numerical Calculation of the Reynolds Stress and Turbulent...July 1983. Also in RECENT ADVANCES IN NUMERICAL METHODS IN FLUIDS, Vol. 3, Editor W.G. Habashi, Pineridge Press. 2. Usab, W.J., "Embedded Mesh Solutions...ridiaconal matrices applicable to approximane factorization methods . E:xlicit algcrit-s are also easier to adapz to multiProcessor arcr.itectures as the
32 CFR 37.1245 - Cash contributions.
Code of Federal Regulations, 2010 CFR
2010-07-01
... REGULATIONS TECHNOLOGY INVESTMENT AGREEMENTS Definitions of Terms Used in This Part § 37.1245 Cash contributions. A recipient's cash expenditures made as contributions toward cost sharing, including expenditures...
Variational adaptive correlation method for flow estimation.
Becker, Florian; Wieneke, Bernhard; Petra, Stefania; Schröder, Andreas; Schnörr, Christoph
2012-06-01
A variational approach is presented to the estimation of turbulent fluid flow from particle image sequences in experimental fluid mechanics. The approach comprises two coupled optimizations for adapting size and shape of a Gaussian correlation window at each location and for estimating the flow, respectively. The method copes with a wide range of particle densities and image noise levels without any data-specific parameter tuning. Based on a careful implementation of a multiscale nonlinear optimization technique, we demonstrate robustness of the solution over typical experimental scenarios and highest estimation accuracy for an international benchmark data set (PIV Challenge).
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.
Hydraulic flow visualization method and apparatus
Karidis, P.G.
1984-12-11
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.
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.
10 CFR 603.1225 - Cash contributions.
Code of Federal Regulations, 2014 CFR
2014-01-01
... 10 Energy 4 2014-01-01 2014-01-01 false Cash contributions. 603.1225 Section 603.1225 Energy DEPARTMENT OF ENERGY (CONTINUED) ASSISTANCE REGULATIONS TECHNOLOGY INVESTMENT AGREEMENTS Definitions of Terms Used in this Part § 603.1225 Cash contributions. A recipient's cash expenditures made as contributions...
10 CFR 603.1225 - Cash contributions.
Code of Federal Regulations, 2013 CFR
2013-01-01
... 10 Energy 4 2013-01-01 2013-01-01 false Cash contributions. 603.1225 Section 603.1225 Energy DEPARTMENT OF ENERGY (CONTINUED) ASSISTANCE REGULATIONS TECHNOLOGY INVESTMENT AGREEMENTS Definitions of Terms Used in this Part § 603.1225 Cash contributions. A recipient's cash expenditures made as contributions...
10 CFR 603.1225 - Cash contributions.
Code of Federal Regulations, 2011 CFR
2011-01-01
... 10 Energy 4 2011-01-01 2011-01-01 false Cash contributions. 603.1225 Section 603.1225 Energy DEPARTMENT OF ENERGY (CONTINUED) ASSISTANCE REGULATIONS TECHNOLOGY INVESTMENT AGREEMENTS Definitions of Terms Used in this Part § 603.1225 Cash contributions. A recipient's cash expenditures made as contributions...
10 CFR 603.1225 - Cash contributions.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 10 Energy 4 2010-01-01 2010-01-01 false Cash contributions. 603.1225 Section 603.1225 Energy DEPARTMENT OF ENERGY (CONTINUED) ASSISTANCE REGULATIONS TECHNOLOGY INVESTMENT AGREEMENTS Definitions of Terms Used in this Part § 603.1225 Cash contributions. A recipient's cash expenditures made as contributions...
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.
Gauge finite element method for incompressible flows
NASA Astrophysics Data System (ADS)
E, Weinan; Liu, Jian-Guo
2000-12-01
A finite element method for computing viscous incompressible flows based on the gauge formulation introduced in [Weinan E, Liu J-G. Gauge method for viscous incompressible flows. Journal of Computational Physics (submitted)] is presented. This formulation replaces the pressure by a gauge variable. This new gauge variable is a numerical tool and differs from the standard gauge variable that arises from decomposing a compressible velocity field. It has the advantage that an additional boundary condition can be assigned to the gauge variable, thus eliminating the issue of a pressure boundary condition associated with the original primitive variable formulation. The computational task is then reduced to solving standard heat and Poisson equations, which are approximated by straightforward, piecewise linear (or higher-order) finite elements. This method can achieve high-order accuracy at a cost comparable with that of solving standard heat and Poisson equations. It is naturally adapted to complex geometry and it is much simpler than traditional finite element methods for incompressible flows. Several numerical examples on both structured and unstructured grids are presented. Copyright
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.
Cash Control for Ticketed Events.
ERIC Educational Resources Information Center
Strickland, Rodney
1991-01-01
Outlines procedures that will provide a school with the ability to accurately record and account for the sales and cash receipts for a ticketed event. Two sample box office reconciliation sheets and one box office issue sheet illustrate the procedures. (MLF)
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.
A topological method for vortex identification in turbulent flows
NASA Astrophysics Data System (ADS)
Zhong, Qiang; Chen, Qigang; Chen, Huai; Li, Danxun
2017-02-01
We present a novel vortex identification method based on structured vorticity (ω s) of the direction field of flow (velocity vectors set to unit magnitude). As a direct measure of streamline curvature is insensitive to vortex strength, ω s is effective in detecting vortices of various strengths. The effectiveness has been tested against both analytical flows (pure shear flow, Oseen vortex flow, strong outward spiraling motion, straining flow, Taylor-Green flow) and experimental flows (closed cavity flow, closed and open channel flow). Comparison of the new method with the swirling-strength method indicates that the new method shows promise as being a simple and effective criterion for vortex identification.
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
QuickCash: Secure Transfer Payment Systems
Alhothaily, Abdulrahman; Alrawais, Arwa; Song, Tianyi; Lin, Bin; Cheng, Xiuzhen
2017-01-01
Payment systems play a significant role in our daily lives. They are an important driver of economic activities and a vital part of the banking infrastructure of any country. Several current payment systems focus on security and reliability but pay less attention to users’ needs and behaviors. For example, people may share their bankcards with friends or relatives to withdraw money for various reasons. This behavior can lead to a variety of privacy and security issues since the cardholder has to share a bankcard and other sensitive information such as a personal identification number (PIN). In addition, it is commonplace that cardholders may lose their cards, and may not be able to access their accounts due to various reasons. Furthermore, transferring money to an individual who has lost their bankcard and identification information is not a straightforward task. A user-friendly person-to-person payment system is urgently needed to perform secure and reliable transactions that benefit from current technological advancements. In this paper, we propose two secure fund transfer methods termed QuickCash Online and QuickCash Offline to transfer money from peer to peer using the existing banking infrastructure. Our methods provide a convenient way to transfer money quickly, and they do not require using bank cards or any identification card. Unlike other person-to-person payment systems, the proposed methods do not require the receiving entity to have a bank account, or to perform any registration procedure. We implement our QuickCash payment systems and analyze their security strengths and properties. PMID:28608846
QuickCash: Secure Transfer Payment Systems.
Alhothaily, Abdulrahman; Alrawais, Arwa; Song, Tianyi; Lin, Bin; Cheng, Xiuzhen
2017-06-13
Payment systems play a significant role in our daily lives. They are an important driver of economic activities and a vital part of the banking infrastructure of any country. Several current payment systems focus on security and reliability but pay less attention to users' needs and behaviors. For example, people may share their bankcards with friends or relatives to withdraw money for various reasons. This behavior can lead to a variety of privacy and security issues since the cardholder has to share a bankcard and other sensitive information such as a personal identification number (PIN). In addition, it is commonplace that cardholders may lose their cards, and may not be able to access their accounts due to various reasons. Furthermore, transferring money to an individual who has lost their bankcard and identification information is not a straightforward task. A user-friendly person-to-person payment system is urgently needed to perform secure and reliable transactions that benefit from current technological advancements. In this paper, we propose two secure fund transfer methods termed QuickCash Online and QuickCash Offline to transfer money from peer to peer using the existing banking infrastructure. Our methods provide a convenient way to transfer money quickly, and they do not require using bank cards or any identification card. Unlike other person-to-person payment systems, the proposed methods do not require the receiving entity to have a bank account, or to perform any registration procedure. We implement our QuickCash payment systems and analyze their security strengths and properties.
Numerical Methods For Chemically Reacting Flows
NASA Technical Reports Server (NTRS)
Leveque, R. J.; Yee, H. C.
1990-01-01
Issues related to numerical stability, accuracy, and resolution discussed. Technical memorandum presents issues in numerical solution of hyperbolic conservation laws containing "stiff" (relatively large and rapidly changing) source terms. Such equations often used to represent chemically reacting flows. Usually solved by finite-difference numerical methods. Source terms generally necessitate use of small time and/or space steps to obtain sufficient resolution, especially at discontinuities, where incorrect mathematical modeling results in unphysical solutions.
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.
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
2013-07-01
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.
Flow cytometric detection method for DNA samples
Nasarabadi, Shanavaz [Livermore, CA; Langlois, Richard G [Livermore, CA; Venkateswaran, Kodumudi S [Round Rock, TX
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.
Buller, Ana Maria; Hidrobo, Melissa; Peterman, Amber; Heise, Lori
2016-06-08
Intimate partner violence (IPV) is highly prevalent and has detrimental effects on the physical and mental health of women across the world. Despite emerging evidence on the impacts of cash transfers on intimate partner violence, the pathways through which reductions in violence occur remain under-explored. A randomised controlled trial of a cash and in-kind food transfer programme on the northern border of Ecuador showed that transfers reduced physical or sexual violence by 30 %. This mixed methods study aimed to understand the pathways that led to this reduction. We conducted a mixed methods study that combined secondary analysis from a randomised controlled trial relating to the impact of a transfer programme on IPV with in-depth interviews and focus group discussions with male and female beneficiaries. A sequential analysis strategy was followed, whereby qualitative results guided the choice of variables for the quantitative analysis and qualitative insights were used to help interpret the quantitative findings. We found qualitative and quantitative evidence that the intervention led to reductions in IPV through three pathways operating at the couple, household and individual level: i) reduced day-to-day conflict and stress in the couple; ii) improved household well-being and happiness; and iii) increased women's decision making, self-confidence and freedom of movement. We found little evidence that any type of IPV increased as a result of the transfers. While cash and in-kind transfers can be important programmatic tools for decreasing IPV, the positive effects observed in this study seem to depend on circumstances that may not exist in all settings or programmes, such as the inclusion of a training component. Moreover, the programme built upon rather than challenged traditional gender roles by targeting women as transfer beneficiaries and framing the intervention under the umbrella of food security and nutrition - domains traditionally ascribed to women
An approximate projection method for incompressible flow
NASA Astrophysics Data System (ADS)
Stevens, David E.; Chan, Stevens T.; Gresho, Phil
2002-12-01
This paper presents an approximate projection method for incompressible flows. This method is derived from Galerkin orthogonality conditions using equal-order piecewise linear elements for both velocity and pressure, hereafter Q1Q1. By combining an approximate projection for the velocities with a variational discretization of the continuum pressure Poisson equation, one eliminates the need to filter either the velocity or pressure fields as is often needed with equal-order element formulations. This variational approach extends to multiple types of elements; examples and results for triangular and quadrilateral elements are provided. This method is related to the method of Almgren et al. (SIAM J. Sci. Comput. 2000; 22: 1139-1159) and the PISO method of Issa (J. Comput. Phys. 1985; 62: 40-65). These methods use a combination of two elliptic solves, one to reduce the divergence of the velocities and another to approximate the pressure Poisson equation. Both Q1Q1 and the method of Almgren et al. solve the second Poisson equation with a weak error tolerance to achieve more computational efficiency.A Fourier analysis of Q1Q1 shows that a consistent mass matrix has a positive effect on both accuracy and mass conservation. A numerical comparison with the widely used Q1Q0 (piecewise linear velocities, piecewise constant pressures) on a periodic test case with an analytic solution verifies this analysis. Q1Q1 is shown to have comparable accuracy as Q1Q0 and good agreement with experiment for flow over an isolated cubic obstacle and dispersion of a point source in its wake.
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
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.
A power function method for estimating base flow.
Lott, Darline A; Stewart, Mark T
2013-01-01
Analytical base flow separation techniques are often used to determine the base flow contribution to total stream flow. Most analytical methods derive base flow from discharge records alone without using basin-specific variables other than basin area. This paper derives a power function for estimating base flow, the form being aQ(b) + cQ, an analytical method calibrated against an integrated basin variable, specific conductance, relating base flow to total discharge, and is consistent with observed mathematical behavior of dissolved solids in stream flow with varying discharge. Advantages of the method are being uncomplicated, reproducible, and applicable to hydrograph separation in basins with limited specific conductance data. The power function relationship between base flow and discharge holds over a wide range of basin areas. It better replicates base flow determined by mass balance methods than analytical methods such as filters or smoothing routines that are not calibrated to natural tracers or empirical basin and gauge-specific variables. Also, it can be used with discharge during periods without specific conductance values, including separating base flow from quick flow for single events. However, it may overestimate base flow during very high flow events. Application of geochemical mass balance and power function base flow separation methods to stream flow and specific conductance records from multiple gauges in the same basin suggests that analytical base flow separation methods must be calibrated at each gauge. Using average values of coefficients introduces a potentially significant and unknown error in base flow as compared with mass balance methods.
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.
Finite area method for nonlinear conical flows
NASA Technical Reports Server (NTRS)
Sritharan, S. S.; Seebass, A. R.
1982-01-01
A fully conservative finite area method for the computation of steady inviscid flow about general conical bodies at incidence is described. The procedure utilizes the potential approximation and implements a body conforming mesh generator. The conical potential is assumed to have its best linear variation inside each mesh cell and a secondary interlocking cell system is used to establish the flux balance required to conserve mass. In the supersonic regions the scheme is desymmetrized by adding appropriate artificial viscosity in conservation form. The algorithm is nearly an order of a magnitude faster than present Euler methods and predicts known results accurately and qualitative features such as nodal point lift off correctly. Results are compared with those of other investigations.
Finite area method for nonlinear conical flows
NASA Technical Reports Server (NTRS)
Sritharan, S. S.; Seebass, A. R.
1982-01-01
A fully conservative finite area method for the computation of steady inviscid flow about general conical bodies at incidence is described. The procedure utilizes the potential approximation and implements a body conforming mesh generator. The conical potential is assumed to have its best linear variation inside each mesh cell and a secondary interlocking cell system is used to establish the flux balance required to conserve mass. In the supersonic regions the scheme is desymmetrized by adding appropriate artificial viscosity in conservation form. The algorithm is nearly an order of a magnitude faster than present Euler methods and predicts known results accurately and qualitative features such as nodal point lift off correctly. Results are compared with those of other investigations.
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.
Implicit methods for computing chemically reacting flow
NASA Astrophysics Data System (ADS)
Li, C. P.
Modeling the inviscid air flow and its constituents over a hypersonically flying body requires a large system of Euler and chemical rate equations in three spatial coordinates. In most cases, the simplest approach to solve for the variables would be based on explicit integration of the governing equations. But the standard techniques are not suitable for this purpose because the integration step size must be inordinately small in order to maintain numerical stability. The difficulty is due to the stiff character of the difference equations, as there exists a large spectrum of spatial and temporal scales in the approximation of physical phenomena by numerical methods. For instance, in the calculation of gradients caused by shock and by cooled wall on a coarse grid, unchecked numerical errors eventually will lead to violent instability, and in calculations of species near chemical equilibrium, a small error in one species will give rise to a large error in the source term for other species. Despite the different nature of the stiffness in a complex system of equations, the most effective approach is believed to be implicit integration. The step increment is no longer dictated by the stability criteria for explicit methods, but instead is dictated by the degree of linearization introduced to the governing equations and by the order of desired accuracy. The linearization is enacted by means of Jacobian matrices, resulting from the differentiation of the flux as well as the rate production terms with respect to dependent variables. The backward Euler scheme is then applied to discretize the partial differential equations and to convert them into a system of linear difference equations in vector form. As this particular approach has the A-stable property, it is the one recommended by Lomax and Bailey(1) for one-dimensional nonequilibrium flow studies. However, in the practice of solving flow problems in multidimensions, it was not clear then how to deal with the mammoth
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
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.
Military Compensation: Balancing Cash and Noncash Benefits
2004-01-16
For greater detail, see N. Gregory Mankiw , Principles of Economics (Fort Worth, Tex.: Dryden Press, 1998), p. 469. 6 CONGRESSIONAL BUDGET OFFICE E C...of it is provided through noncash benefits. Greater Choice. Cash pay is more efficient than non- cash compensation in an economic sense because cash...Pleeter, “The Personal Dis- count Rate: Evidence from Military Downsizing Programs,” American Economic Review, vol. 91, no. 1 (2001), pp. 33-53. 8
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.
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.
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
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.
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.
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.
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…
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.
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.
Method and apparatus for measuring flow velocity using matched filters
Raptis, A.C.
1981-07-17
An apparatus and method for measuring the flow velocities of individual phase flow components of a multiphase flow is disclosed. 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.
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.
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
Innovative Method of Greatly Reducing Flow Resistance
NASA Astrophysics Data System (ADS)
Lin, Weiyi
2008-11-01
In this paper, firstly, the aerated pipe flow experiment is introduced. And some experimental research on comparison between different volumes of air entrained is presented. Secondly, the technical characteristics of gravity pipe flow under the action of Torricelli's vacuum, shortly called as GPFUTV are dissertated, including creative and functional design, fundamental principle and the strange energy loss phenomena, etc. Thirdly, an appeal in relation to the experimental research, the applied studies and basic theory research is given. For instance, Reynolds' experiment under GPFUTV condition, the potential for GPFUTV to be developed for deep seawater suction technology and lifting technology for deep ocean mining, flow stability and flow resistance under GPFUTV condition, etc.
A Good President Rates a Cash Bonus.
ERIC Educational Resources Information Center
Dane, Roger; Koenig, Allen E.
1981-01-01
Emerson College's board rewarded its president for outstanding performance with a cash bonus of 36 percent of salary. The cash bonus idea is offered as one novel compensation plan for college presidents, but it is suggested that trustees can act as opinion leaders for implementing other creative compensation plans. (MLW)
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.…
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, 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...
A Good President Rates a Cash Bonus.
ERIC Educational Resources Information Center
Dane, Roger; Koenig, Allen E.
1981-01-01
Emerson College's board rewarded its president for outstanding performance with a cash bonus of 36 percent of salary. The cash bonus idea is offered as one novel compensation plan for college presidents, but it is suggested that trustees can act as opinion leaders for implementing other creative compensation plans. (MLW)
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 provide...
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 provide...
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.…
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…
Underground stope optimization with network flow method
NASA Astrophysics Data System (ADS)
Bai, Xiaoyu; Marcotte, Denis; Simon, Richard
2013-03-01
A new algorithm to optimize stope design for the sublevel stoping mining method is described. The model is based on a cylindrical coordinate defined around the initial vertical raise. Geotechnical constraints on hanging wall and footwall slopes are translated as precedence relations between blocks in the cylindrical coordinate system. Two control parameters with clear engineering meaning are defined to further constrain the solution: (a) the maximum distance of a block from the raise and (b) the horizontal width required to bring the farthest block to the raise. The graph obtained is completed by the addition of a source and a sink node allowing to transform the optimization program to a problem of maximum flow over the graph. The (conditional) optimal stope corresponding to the current raise location and height is obtained. The best location and height for the raise are determined by global optimization. The performance of the algorithm is evaluated with three simple synthetic deposits and one real deposit. Comparison is made with the floating stope technique. The results show that the algorithm effectively meets the geotechnical constraints and control parameters, and produce realistic optimal stope for engineering use.
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.
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.
Methods of similitude in granular avalanche flows
NASA Astrophysics Data System (ADS)
Tai, Yih-Chin; Wang, Yongqi; Gray, J. M. N. T.; Hutter, Kolumban
Snow avalanches are relatively dry and dense granular flows for which the Savage-Hutter (SH) equations have been demonstrated to be an adequate mathematical model. We review these equations and point out for which cases the equations have been tested against laboratory experiments. Since the equations are scale invariant and because agreement with experiments is good, laboratory experiments can be used to test realistic flows. This is detailed in this paper. We demonstrate how shocks are formed when dilatational flow states merge into compacting states and show that shock formation is an essential mechanism in flows against obstructions. We finally apply the theory of similitude to the design of a projected avalanche protection structure of the Schneefernerhaus at the Zugspitze.
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.
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.
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.
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.
Microfluidic flow-flash: method for investigating protein dynamics.
Toepke, Michael W; Brewer, Scott H; Vu, Dung M; Rector, Kirk D; Morgan, Joel E; Gennis, Robert B; Kenis, Paul J A; Dyer, R Brian
2007-01-01
We report a new method, microfluidic flow-flash, for measuring protein reaction kinetics. The method couples a microscope imaging detection system with a microfluidic flow cell to reduce data acquisition times and sample consumption. This combination allows for the simultaneous collection of spectral and temporal information. The microfluidic flow cell design utilizes three-dimensional sheath flow to reduce sample dispersion and minimize sample consumption. The ability to alter the flow rates in the microfluidic flow cells allows a variety of time scales to be studied with submillisecond time resolution. The imaging detection system can be coupled with several spectroscopic probes including fluorescence and UV/visible absorbance spectroscopy. Here, we utilize the microfluidic flow-flash method to probe the kinetics of CO recombination or O2 binding to myoglobin after the laser-induced photolysis of CO from myoglobin by UV/visible absorbance spectral imaging.
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.
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 not...
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 not...
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...
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...
Estimating the level of cash invested in financial markets
NASA Astrophysics Data System (ADS)
Andersen, Jørgen Vitting
2004-12-01
Long-term trends of financial markets are considered as a growth phenomenon, with a steady influx of money needed to ensure a sustainable growth. A study is made of the impact of money supply, dividends and interest rates, on the growth of a market. A method to estimate the level of investment of cash into stocks is introduced, thereby eventually also identifying periods when stock markets are likely to have topped.
Banknotes and unattended cash transactions
NASA Astrophysics Data System (ADS)
Bernardini, Ronald R.
2000-04-01
There is a 64 billion dollar annual unattended cash transaction business in the US with 10 to 20 million daily transactions. Even small problems with the machine readability of banknotes can quickly become a major problem to the machine manufacturer and consumer. Traditional note designs incorporate overt security features for visual validation by the public. Many of these features such as fine line engraving, microprinting and watermarks are unsuitable as machine readable features in low cost note acceptors. Current machine readable features, mostly covert, were designed and implemented with the central banks in mind. These features are only usable by the banks large, high speed currency sorting and validation equipment. New note designs should consider and provide for low cost not acceptors, implementing features developed for inexpensive sensing technologies. Machine readable features are only as good as their consistency. Quality of security features as well as that of the overall printing process must be maintained to ensure reliable and secure operation of note readers. Variations in printing and of the components used to make the note are one of the major causes of poor performance in low cost note acceptors. The involvement of machine manufacturers in new currency designs will aid note producers in the design of a note that is machine friendly, helping to secure the acceptance of the note by the public as well as acting asa deterrent to fraud.
Impulse-based methods for fluid flow
Cortez, Ricardo
1995-05-01
A Lagrangian numerical method based on impulse variables is analyzed. A relation between impulse vectors and vortex dipoles with a prescribed dipole moment is presented. This relation is used to adapt the high-accuracy cutoff functions of vortex methods for use in impulse-based methods. A source of error in the long-time implementation of the impulse method is explained and two techniques for avoiding this error are presented. An application of impulse methods to the motion of a fluid surrounded by an elastic membrane is presented.
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.
Ultrasonic fluid flow measurement method and apparatus
Kronberg, J.W.
1992-12-31
This invention is comprised of 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.
Ultrasonic 3-D Vector Flow Method for Quantitative In Vivo Peak Velocity and Flow Rate Estimation.
Holbek, Simon; Ewertsen, Caroline; Bouzari, Hamed; Pihl, Michael Johannes; Hansen, Kristoffer Lindskov; Stuart, Matthias Bo; Thomsen, Carsten; Nielsen, Michael Bachmann; Jensen, Jorgen Arendt
2017-03-01
Current clinical ultrasound (US) systems are limited to show blood flow movement in either 1-D or 2-D. In this paper, a method for estimating 3-D vector velocities in a plane using the transverse oscillation method, a 32×32 element matrix array, and the experimental US scanner SARUS is presented. The aim of this paper is to estimate precise flow rates and peak velocities derived from 3-D vector flow estimates. The emission sequence provides 3-D vector flow estimates at up to 1.145 frames/s in a plane, and was used to estimate 3-D vector flow in a cross-sectional image plane. The method is validated in two phantom studies, where flow rates are measured in a flow-rig, providing a constant parabolic flow, and in a straight-vessel phantom ( ∅=8 mm) connected to a flow pump capable of generating time varying waveforms. Flow rates are estimated to be 82.1 ± 2.8 L/min in the flow-rig compared with the expected 79.8 L/min, and to 2.68 ± 0.04 mL/stroke in the pulsating environment compared with the expected 2.57 ± 0.08 mL/stroke. Flow rates estimated in the common carotid artery of a healthy volunteer are compared with magnetic resonance imaging (MRI) measured flow rates using a 1-D through-plane velocity sequence. Mean flow rates were 333 ± 31 mL/min for the presented method and 346 ± 2 mL/min for the MRI measurements.
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.
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.
Dye visualization--a method for investigating biomechanical flows.
Leweke, Thomas
2012-09-01
Flow visualization using dye is an inexpensive and easy-to-implement experimental technique. It can be used for a rapid qualitative assessment of fluid flows in configurations relevant to biomedical or biotechnological applications, which often involve small spatial dimensions and flow velocities (low Reynolds numbers). This paper gives an overview of the practical aspects related to dye visualization in liquids (dyes, introduction of dye into the flow, illumination), and discusses the information that can be obtained by this method, which includes the distribution of coherent structures/ vortices, the location of recirculation zones, and certain characteristic spatial and temporal scales. Visualization results for three examples of generic flows related to biomechanical applications are presented: the flow behind a contraction in a pipe (stenosis), the wake of a particle moving along a wall, and the flow inside a lid-driven mixing vessel (bioreactor).
Polynomial interpolation methods for viscous flow calculations
NASA Technical Reports Server (NTRS)
Rubin, S. G.; Khosla, P. K.
1977-01-01
Higher-order collocation procedures which result in block-tridiagonal matrix systems are derived from (1) Taylor series expansions and from (2) polynomial interpolation, and the relationships between the two formulations, called respectively Hermite and spline collocation, are investigated. A Hermite block-tridiagonal system for a nonuniform mesh is derived, and the Hermite approach is extended in order to develop a variable-mesh sixth-order block-tridiagonal procedure. It is shown that all results obtained by Hermite development can be recovered by appropriate spline polynomial interpolation. The additional boundary conditions required for these higher-order procedures are also given. Comparative solutions using second-order accurate finite difference and spline and Hermite formulations are presented for the boundary layer on a flat plate, boundary layers with uniform and variable mass transfer, and the viscous incompressible Navier-Stokes equations describing flow in a driven cavity.
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.
Adaptive implicit-explicit methods for flow problems
NASA Technical Reports Server (NTRS)
Liou, J.; Tezduyar, T. E.
1989-01-01
Studies on the adaptive implicit-explicit (AIE) method for large-scale problems are presented. The AIE method is based on dynamic grouping of the elements into the implicit and explicit subsets as dictated by the element level stability and accuracy considerations. The method has been applied to various flow problems including the incompressible flow and convection-diffusion problems, and it has been demonstrated that substantial savings in CPU time and memory can be achieved.
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.
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.
Thirumurthy, Harsha; Halpern, Carolyn Tucker; Pettifor, Audrey; Handa, Sudhanshu
2015-01-01
Purpose This study investigates the causal effect of Kenya's unconditional cash transfer program on mental health outcomes of young people. Methods Selected Locations in Kenya were randomly assigned to receive unconditional cash transfers in the first phase of Kenya's Cash Transfer Program for Orphans and Vulnerable Children (CT-OVC). In intervention Locations, low-income households and those with OVCs began receiving monthly cash transfers of $20 in 2007. In 2011, four years after program onset, data were collected on the psychosocial status for youth aged 15-24 from households in intervention and control Locations (N=1960). The primary outcome variable was an indicator of depressive symptoms using the 10-question Center for Epidemiologic Studies Depression Scale (CES-D10). Secondary outcomes include Hope and physical health measures. Logistic regression models that adjusted for individual and household characteristics were used to determine the effect of the cash transfer program. Results The cash transfer reduced the odds of depressive symptoms by 24 percent among young persons living in households that received cash transfers. Further analysis by gender and age revealed that the effects were only significant for young men and were larger among men aged 20-24 and orphans. Conclusions This study provides evidence that poverty targeted unconditional cash transfer programs, can improve the mental health of young people in low-income countries. PMID:26576822
Method analyzes pressure for short flow times
Soliman, M. ); Petak, K. )
1990-04-30
Pressure build-up after short producing times and pressure surges can be analyzed. The method employs the derivative plot and does not require prior knowledge of initial reservoir pressure that may be calculated using a Cartesian plot. Field use of the new technique has proven its superiority to previously used methods, and has shown the necessity of using highly accurate data to achieve desired results.
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
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; Joo, Chulmin; Choi, Jung-il; Seo, Jin Keun
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.
Lattice Boltzmann Method for Two-Dimensional Unsteady Incompressible Flow
NASA Astrophysics Data System (ADS)
Mužík, Juraj
2016-12-01
A Lattice Boltzmann method is used to analyse incompressible fluid flow in a two-dimensional cavity and flow in the channel past cylindrical obstacle. The method solves the Boltzmann's transport equation using simple computational grid - lattice. With the proper choice of the collision operator, the Boltzmann's equation can be converted into incompressible Navier-Stokes equation. Lid-driven cavity benchmark case for various Reynolds numbers and flow past cylinder is presented in the article. The method produces stable solutions with results comparable to those in literature and is very easy to implement.
Cross-flow electrofilter and method
Gidaspow, Dimitri; Lee, Chang H.; Wasan, Darsh T.
1980-01-01
A filter for clarifying carbonaceous liquids containing finely divided solid particles of, for instance, unreacted coal, ash and other solids discharged from a coal liquefaction process is presented. The filter includes two passageways separated by a porous filter medium. In one preferred embodiment the filter medium is of tubular shape to form the first passageway and is enclosed within an outer housing to form the second passageway within the annulus. An electrode disposed in the first passageway, for instance along the tube axis, is connected to a source of high voltage for establishing an electric field between the electrode and the filter medium. Slurry feed flows through the first passageway tangentially to the surfaces of the filter medium and the electrode. Particles from the feed slurry are attracted to the electrode within the first passageway to prevent plugging of the porous filter medium while carbonaceous liquid filters into the second passageway for withdrawal. Concentrated slurry is discharged from the first passageway at an end opposite to the feed slurry inlet. Means are also provided for the addition of diluent and a surfactant into the slurry to control relative permittivity and the electrophoretic mobility of the particles.
Flow visualization for Lagrangian particle methods
Glass, M.W.; Kempka, S.N.
1994-05-01
In particle methods, each particle represents a finite region over which there is a distribution of the field quantity of interest. The field value at any point is calculated by summing the distribution functions for all the particles. This summation procedure does not require the use of any connectivities to generate continuous fields. Various AVS modules and networks have been developed that enable us to visualize the results from particle methods. This will be demonstrated by visualizing a numerical simulation of a rising, chaotic bubble. In this fluid dynamics simulation, each particle represents a region with a specified vorticity distribution.
A conservative interface method for compressible flows
NASA Astrophysics Data System (ADS)
Hu, X. Y.; Khoo, B. C.; Adams, N. A.; Huang, F. L.
2006-12-01
In this work, we present a conservative interface method for both multi-fluid and complex boundary problems, in which the standard finite volume scheme on Cartesian grids is modified by considering computational cells being cut by interface. While the discretized governing equations are updated conservatively, the method treats the topological changes naturally by combining interface description and geometric operations with a level set technique. Extensive tests in 1D are carried out, and 2D examples suggest that the present scheme is able to handle multi-fluid and complex (static or moving) boundary problems in a straightforward way with good robustness and accuracy.
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.
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.
Manage Your Cash for Success! A Guide for Beginning School Business Officials.
ERIC Educational Resources Information Center
Johnson, Donald R.
2000-01-01
A cash-flow plan allows districts lead time for investing, borrowing, reducing or delaying expenditures, expanding revenue sources, informing the community, and avoiding surprises. Planners should identify type, timing, and amount of revenues and expenditures and then compare revenues and expenditures to determine (and accommodate) shortfalls or…
Manage Your Cash for Success! A Guide for Beginning School Business Officials.
ERIC Educational Resources Information Center
Johnson, Donald R.
2000-01-01
A cash-flow plan allows districts lead time for investing, borrowing, reducing or delaying expenditures, expanding revenue sources, informing the community, and avoiding surprises. Planners should identify type, timing, and amount of revenues and expenditures and then compare revenues and expenditures to determine (and accommodate) shortfalls or…
Red blood cell tracking using optical flow methods.
Guo, Dongmin; van de Ven, Anne L; Zhou, Xiaobo
2014-05-01
The investigation of microcirculation is an important task in biomedical and physiological research because the microcirculation information, such as flow velocity and vessel density, is critical to monitor human conditions and develop effective therapies of some diseases. As one of the tasks of the microcirculation study, red blood cell (RBC) tracking presents an effective approach to estimate some parameters in microcirculation. The common method for RBC tracking is based on spatiotemporal image analysis, which requires the image to have high qualification and cells should have fixed velocity. Besides, for in vivo cell tracking, cells may disappear in some frames, image series may have spatial and temporal distortions, and vessel distribution can be complex, which increase the difficulties of RBC tracking. In this paper, we propose an optical flow method to track RBCs. It attempts to describe the local motion for each visible point in the frames using a local displacement vector field. We utilize it to calculate the displacement of a cell in two adjacent frames. Additionally, another optical flow-based method, scale invariant feature transform (SIFT) flow, is also presented. The experimental results show that optical flow is quite robust to the case where the velocity of cell is unstable, while SIFT flow works well when there is a large displacement of the 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.
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.
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.
A flux monitoring method for easy and accurate flow rate measurement in pressure-driven flows.
Siria, Alessandro; Biance, Anne-Laure; Ybert, Christophe; Bocquet, Lydéric
2012-03-07
We propose a low-cost and versatile method to measure flow rate in microfluidic channels under pressure-driven flows, thereby providing a simple characterization of the hydrodynamic permeability of the system. The technique is inspired by the current monitoring method usually employed to characterize electro-osmotic flows, and makes use of the measurement of the time-dependent electric resistance inside the channel associated with a moving salt front. We have successfully tested the method in a micrometer-size channel, as well as in a complex microfluidic channel with a varying cross-section, demonstrating its ability in detecting internal shape variations.
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...
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...
Characterization of peak flow events with local singularity method
NASA Astrophysics Data System (ADS)
Cheng, Q.; Li, L.; Wang, L.
2009-07-01
Three methods, return period, power-law frequency plot (concentration-area) and local singularity index, are introduced in the paper for characterizing peak flow events from river flow data for the past 100 years from 1900 to 2000 recorded at 25 selected gauging stations on rivers in the Oak Ridges Moraine (ORM) area, Canada. First a traditional method, return period, was applied to the maximum annual river flow data. Whereas the Pearson III distribution generally fits the values, a power-law frequency plot (C-A) on the basis of self-similarity principle provides an effective mean for distinguishing "extremely" large flow events from the regular flow events. While the latter show a power-law distribution, about 10 large flow events manifest departure from the power-law distribution and these flow events can be classified into a separate group most of which are related to flood events. It is shown that the relation between the average water releases over a time period after flow peak and the time duration may follow a power-law distribution. The exponent of the power-law or singularity index estimated from this power-law relation may be used to characterize non-linearity of peak flow recessions. Viewing large peak flow events or floods as singular processes can anticipate the application of power-law models not only for characterizing the frequency distribution of peak flow events, for example, power-law relation between the number and size of floods, but also for describing local singularity of processes such as power-law relation between the amount of water released versus releasing time. With the introduction and validation of singularity of peak flow events, alternative power-law models can be used to depict the recession property as well as other types of non-linear properties.
Flow measurement on an oscillating pipe flow near the entrance using the UVP method
NASA Astrophysics Data System (ADS)
Yamanaka, G.; Kikura, H.; Takeda, Y.; Aritomi, M.
The authors have carried out a study to investigate and clarify the characteristics of purely oscillating pipe flows over the developing region. The main objective of this study is to establish the method of time-dependent velocity profiles obtained by the ultrasonic velocity profile (UVP) measurement method. First, the relationship between the test fluids and the microparticles, as reflectors of ultrasonic pulses, was investigated. In addition, the relationship between the sound speeds of the test fluids and the wall materials was studied. Second, the UVP was used to obtain the instantaneous velocity profiles in oscillating pipe flows, and the developing characteristics of the flows were analyzed. Finally, the ``entrance length'' (by analogy with a unidirectional pipe flow) required for oscillating pipe flows was analyzed by examining the amplitude of the harmonic spectral components of the oscillating frequency. A fast Fourier transform (FFT) is proposed as the applicable method to estimate the ``entrance length''. From the Fourier transform of the velocity on the centerline, nonlinear oscillation of fluid occurs in the ``entrance length'' of the oscillating flows, and the viscous dissipation of the higher-order velocity harmoncis determines the entrance region. The ``entrance length'' can be obtained from the dissipation length of the third-order harmonic. These results prove that the UVP method is highly applicable to carry out the flow measurement in the ``entrance length'' of oscillating pipe flow.
Flow measurement on oscillating pipe flow near the entrance using the UVP method
NASA Astrophysics Data System (ADS)
Yamanaka, G.; Kikura, H.; Takeda, Y.; Aritomi, M.
2003-02-01
The authors have carried out a study to investigate and clarify the characteristics of purely oscillating pipe flows over the developing region. The main objective of this study is to establish the method of time-dependent velocity profiles obtained by the ultrasonic velocity profile (UVP) measurement method. First, the relationship between the test fluids and the micro-particles, as reflectors of ultrasonic pulses, was investigated, and also the relationship between the sound speeds of the test fluids and wall materials was studied. Second, the UVP was used to obtain the instantaneous velocity profiles in oscillating pipe flows, and the developing characteristics of the flows were analyzed. Finally, the "entrance length" (analogy with a unidirectional pipe flow) required for oscillating pipe flows were analyzed examining the amplitude of the harmonic spectral components of the oscillating frequency. The fast Fourier transform (FFT) is proposed as the applicable method to estimate the "entrance length". From the Fourier transform of the velocity on the centerline, nonlinear oscillation of fluid occurs in the "entrance length" of the oscillating flows, and the viscous dissipation of the higher order velocity harmonics determines the entrance region. The "entrance length" can be obtained from the dissipation length of the third order harmonic. These results prove that the UVP method is highly applicable for carrying out flow measurements in the "entrance length" of the oscillating pipe flow.
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.
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.
NASA Astrophysics Data System (ADS)
Qin, C. C.
2014-12-01
Several secondary flow correction methods had been proposed in literature to account for the 3d flow characteristics of secondary circulation which was often lost in depth-averaged models. In order to evaluate their performances in singular bend, successive reverse curvature bends and natural meander rivers, three different typical secondary flow correction methods were applied to a depth-averaged hydrodynamic model, which were Lien(L), Kalkwijk and Booij(K) and modified Finnie(F) methods. There are obviously limits to the descriptive ability of the three methods in simulating sharply bend channels, especially L method which showed qualitative error. As for successive reverse curvature bends and natural meander rivers, K method gave a better performance than the others. F method increased depth-averaged velocities on the outside of curves, while L method overestimated the whole flow field. By the order of magnitude analysis, we found that L method has done the maximum correction for the secondary flow and the minimum correction for transversal velocities was F method. Those three methods were evaluated by multiple performance criteria. The results of this study can provide some references for some practical applications.
New method to measure coronary velocity and coronary flow reserve.
Zhang, Z-D; Svendsen, M; Choy, J S; Sinha, A K; Huo, Y; Yoshida, K; Molloi, S; Kassab, G S
2011-07-01
Coronary flow reserve (CFR) is an important index of coronary microcirculatory function. The objective of this study was to validate the reproducibility and accuracy of intravascular conductance catheter-based method for measurements of baseline and hyperemic coronary flow velocity (and hence CFR). The absolute coronary blood velocity was determined by measuring the time of transit of a saline injection between two pairs of electrodes (known distance) on a conductance catheter during a routine saline injection without the need for reference flow. In vitro validation was made in the velocity range of 5 to 70 cm/s in reference to the volume collection method. In 10 swine, velocity measurements were compared with those from a flow probe in coronary arteries at different CFR attained by microsphere embolization. In vitro, the mean difference between the proposed method and volume collection was 0.7 ± 1.34 cm/s for steady flow and -0.77 ± 2.22 cm/s for pulsatile flow. The mean difference between duplicate measurements was 0 ± 1.4 cm/s. In in vivo experiments, the flow (product of velocity and lumen cross-sectional area that is also measured by the conductance catheter) was determined in both normal and stenotic vessels and the mean difference between the proposed method and flow probe was -1 ± 12 ml/min (flow ranged from 10 to 130 ml/min). For CFR, the mean difference between the two methods was 0.06 ± 0.28 (range of 1 to 3). Our results demonstrate the reproducibility and accuracy of velocity and CFR measurements with a conductance catheter by use of a standard saline injection. The ability of the combined measurement of coronary lumen area (as previously validated) and current velocity and CFR measurements provides an integrative diagnostic tool for interventional cardiology.
Blood flow quantification using optical flow methods in a body fitted coordinate system
NASA Astrophysics Data System (ADS)
Maday, Peter; Brosig, Richard; Endres, Jurgen; Kowarschik, Markus; Navab, Nassir
2014-03-01
In this paper a blood flow quantification method that is based on a physically motivated dense 2D flow estimation algorithm is outlined. It yields accurate time varying volumetric flow rate measurements based on digital subtraction angiography (DSA) image sequences, with robustness to significant inter-frame displacements. Time varying volumetric flow rates are estimated for individual non-branching vascular segments based on the estimated 2D flow fields and a 3D vessel segmentation from a 3D Rotational Angiography (3DRA) acquisition. The novelty of the approach lies in the use of a vessel aligned coordinate system for the problem formulation. The coordinate functions are generated using the Schwarz-Christoffel1(SC) map that yields a solution with coordinate lines aligned with the vessel boundaries. The use of vessel aligned coordinates enables the easy and accurate handling of boundary conditions in the irregular domain of a vessel lumen while only requiring slight modifications to the used finite difference approach. Unlike traditional coarse to fine methods we use an anisotropic scaling strategy that enables the estimation of flows with larger inter frame displacements. The evaluation of our method is based on highly realistic synthetic DSA datasets for a number of cases. Ground truth volumetric flow rate values are compared against the measurements and a high degree of fidelity is observed. Performance measures are obtained with varying flow velocities and acquisition rates.
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.
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.
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 other...
19 CFR 10.40 - Refund of cash deposits.
Code of Federal Regulations, 2010 CFR
2010-04-01
... 19 Customs Duties 1 2010-04-01 2010-04-01 false Refund of cash deposits. 10.40 Section 10.40... TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. General Provisions Temporary Importations Under Bond § 10.40 Refund of cash deposits. (a) When a cash deposit is made in lieu of surety,...
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... advances to members as provided in § 950.5 of this chapter, and may price such advances at rates below...
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.
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…
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...
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…
Powder Flow Testing: Judicious Choice of Test Methods.
Tay, Justin Yong Soon; Liew, Celine Valeria; Heng, Paul Wan Sia
2016-11-14
Flow property of pharmaceutical powders can be assessed by various flow testers and test methods. In this study, eight commercially available lactose grades were sourced and tested for angles of repose, tapping studies, shear cell measurements, stirred powder rheometry, and avalanching powder measurements. The relationships between various flow parameters and particle size were analyzed. Deviations from the general trend could be attributed to either the insensitivity of the test or differences in particle shape. The basic flowability energy of the powder rheometer was unable to reconcile the effects of shape and particle size on powder flowability. Avalanche time of the revolving drum powder analyzer and angle of repose exhibited good correlation with each other (r = 0.92) but experienced poor resolution for samples of smaller particle sizes due to powder cohesiveness and the propensity for agglomerative flow. Flow test parameters could be categorized into three broad types, based on their relationship with particle size: (i) linear relationship, (ii) test parameter more sensitive to smaller sized particles, and (iii) test parameter more sensitive to larger sized particles. Choice of test parameters used to represent powder flow should be dependent on the sensitivity of the selected flow test methods to the sample types.
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.
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.
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 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
A Numerical Method for Incompressible Flow with Heat Transfer
NASA Technical Reports Server (NTRS)
Sa, Jong-Youb; Kwak, Dochan
1997-01-01
A numerical method for the convective heat transfer problem is developed for low speed flow at mild temperatures. A simplified energy equation is added to the incompressible Navier-Stokes formulation by using Boussinesq approximation to account for the buoyancy force. A pseudocompressibility method is used to solve the resulting set of equations for steady-state solutions in conjunction with an approximate factorization scheme. A Neumann-type pressure boundary condition is devised to account for the interaction between pressure and temperature terms, especially near a heated or cooled solid boundary. It is shown that the present method is capable of predicting the temperature field in an incompressible flow.
A time accurate finite volume method for propulsion chamber flows
NASA Technical Reports Server (NTRS)
Beddini, R. A.; Ridder, J. P.
1989-01-01
An implicit three-dimensional time-accurate method for propulsion chamber flows is proposed which uses line Gauss-Seidel relaxation and multiple axial sweeps for the convergence of each time step. The general time-integration algorithm employed includes such schemes as the Euler implicit method. The results of spatial and temporal accuracy tests reveal that Roe's (1981) flux difference splitting provides excellent tracking of acoustic wave speeds. In comparison with other methods, no low mean flow Mach number convergence limitation or Courant number stabilization restriction is observed.
Applying flow chemistry: methods, materials, and multistep synthesis.
McQuade, D Tyler; Seeberger, Peter H
2013-07-05
The synthesis of complex molecules requires control over both chemical reactivity and reaction conditions. While reactivity drives the majority of chemical discovery, advances in reaction condition control have accelerated method development/discovery. Recent tools include automated synthesizers and flow reactors. In this Synopsis, we describe how flow reactors have enabled chemical advances in our groups in the areas of single-stage reactions, materials synthesis, and multistep reactions. In each section, we detail the lessons learned and propose future directions.
Uncertainty-Based Design Methods for Flow-Structure Interactions
2007-06-01
07 Final _ 2/01/05 - 01/31/07 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Uncertainty-based Design Methods for Flow- N00014-04-1-0007 Structure ...project is to develop advanced tools for efficient simulations of flow- structure interactions that account for random excitation and uncertain input...with emphasis on realistic three-dimensional nonlinear representatiol of the structures of interest. This capability will set the foundation for the
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.
Higher-Order Panel Method for Aerodynamic Flow Analysis
NASA Technical Reports Server (NTRS)
Erickson, L.; Carmichael, R. L.; Levin, A. D.; Magnus, A.; Epton, M.; Baruah, P.; Massena, B.; Bussoletti, J.; Sidwell, K.; Johnson, F.;
1982-01-01
PANAIR uses high-order panel method to predict inviscid subsonic or supersonic flows about arbitrary configuration. Panel method solves linear partial differential equation numerically by approximating configuration surface with panels on which unknown "singularity strengths" are defined. PANAIR includes advanced software technology as well as advanced aerodynamic technology.
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...
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...
Higher-Order Panel Method for Aerodynamic Flow Analysis
NASA Technical Reports Server (NTRS)
Erickson, L.; Carmichael, R. L.; Levin, A. D.; Magnus, A.; Epton, M.; Baruah, P.; Massena, B.; Bussoletti, J.; Sidwell, K.; Johnson, F.; Zeppa, J.; Bates, G.; Clemens, D.; Derbyshire, T.; Purdon, D.; Chiang, D.; Rubbert, P.; Nelson, F.; Wai, J.; Tsurusaki, K.; Smith, N.; Snyder, J. R.; Sotomayer, W.; Dejongh, J.; Thomas, J. L.
1982-01-01
PANAIR uses high-order panel method to predict inviscid subsonic or supersonic flows about arbitrary configuration. Panel method solves linear partial differential equation numerically by approximating configuration surface with panels on which unknown "singularity strengths" are defined. PANAIR includes advanced software technology as well as advanced aerodynamic technology.
An update on projection methods for transient incompressible viscous flow
Gresho, P.M.; Chan, S.T.
1995-07-01
Introduced in 1990 was the biharmonic equation (for the pressure) and the concomitant biharmonic miracle when transient incompressible viscous flow is solved approximately by a projection method. Herein is introduced the biharmonic catastrophe that sometimes occurs with these same projection methods.
Code of Federal Regulations, 2010 CFR
2010-04-01
... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Cash. 256.131 Section 256.131 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) UNIFORM SYSTEM OF ACCOUNTS FOR MUTUAL SERVICE COMPANIES AND SUBSIDIARY SERVICE COMPANIES, PUBLIC UTILITY HOLDING COMPANY ACT OF...
Code of Federal Regulations, 2011 CFR
2011-04-01
... 17 Commodity and Securities Exchanges 3 2011-04-01 2011-04-01 false Cash. 256.131 Section 256.131 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) UNIFORM SYSTEM OF ACCOUNTS FOR MUTUAL SERVICE COMPANIES AND SUBSIDIARY SERVICE COMPANIES, PUBLIC UTILITY HOLDING COMPANY ACT OF...
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.
Conditional Cash Transfers and School Dropout Rates
ERIC Educational Resources Information Center
Dearden, Lorraine; Emmerson, Carl; Frayne, Christine; Meghir, Costas
2009-01-01
This paper evaluates a United Kingdom pilot study designed to test whether a means-tested conditional cash transfer paid to 16- to 18-year-olds for staying in full-time education is an effective way of reducing the proportion of school dropouts. The transfer's impact is substantial: In the first year, full-time education participation rates…
Conditional Cash Transfers and School Dropout Rates
ERIC Educational Resources Information Center
Dearden, Lorraine; Emmerson, Carl; Frayne, Christine; Meghir, Costas
2009-01-01
This paper evaluates a United Kingdom pilot study designed to test whether a means-tested conditional cash transfer paid to 16- to 18-year-olds for staying in full-time education is an effective way of reducing the proportion of school dropouts. The transfer's impact is substantial: In the first year, full-time education participation rates…
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.
10 CFR 603.1225 - Cash contributions.
Code of Federal Regulations, 2012 CFR
2012-01-01
... 10 Energy 4 2012-01-01 2012-01-01 false Cash contributions. 603.1225 Section 603.1225 Energy DEPARTMENT OF ENERGY (CONTINUED) ASSISTANCE REGULATIONS TECHNOLOGY INVESTMENT AGREEMENTS Definitions of Terms... toward cost sharing, including expenditures of money that third parties contributed to the recipient....
24 CFR 203.411 - Cash adjustment.
Code of Federal Regulations, 2014 CFR
2014-04-01
... DEVELOPMENT MORTGAGE AND LOAN INSURANCE PROGRAMS UNDER NATIONAL HOUSING ACT AND OTHER AUTHORITIES SINGLE... 24 Housing and Urban Development 2 2014-04-01 2014-04-01 false Cash adjustment. 203.411 Section 203.411 Housing and Urban Development Regulations Relating to Housing and Urban Development...
24 CFR 203.411 - Cash adjustment.
Code of Federal Regulations, 2012 CFR
2012-04-01
... DEVELOPMENT MORTGAGE AND LOAN INSURANCE PROGRAMS UNDER NATIONAL HOUSING ACT AND OTHER AUTHORITIES SINGLE... 24 Housing and Urban Development 2 2012-04-01 2012-04-01 false Cash adjustment. 203.411 Section 203.411 Housing and Urban Development Regulations Relating to Housing and Urban Development...
24 CFR 203.411 - Cash adjustment.
Code of Federal Regulations, 2010 CFR
2010-04-01
... DEVELOPMENT MORTGAGE AND LOAN INSURANCE PROGRAMS UNDER NATIONAL HOUSING ACT AND OTHER AUTHORITIES SINGLE... 24 Housing and Urban Development 2 2010-04-01 2010-04-01 false Cash adjustment. 203.411 Section 203.411 Housing and Urban Development Regulations Relating to Housing and Urban Development...
24 CFR 203.411 - Cash adjustment.
Code of Federal Regulations, 2013 CFR
2013-04-01
... DEVELOPMENT MORTGAGE AND LOAN INSURANCE PROGRAMS UNDER NATIONAL HOUSING ACT AND OTHER AUTHORITIES SINGLE... 24 Housing and Urban Development 2 2013-04-01 2013-04-01 false Cash adjustment. 203.411 Section 203.411 Housing and Urban Development Regulations Relating to Housing and Urban Development...
24 CFR 203.411 - Cash adjustment.
Code of Federal Regulations, 2011 CFR
2011-04-01
... DEVELOPMENT MORTGAGE AND LOAN INSURANCE PROGRAMS UNDER NATIONAL HOUSING ACT AND OTHER AUTHORITIES SINGLE... 24 Housing and Urban Development 2 2011-04-01 2011-04-01 false Cash adjustment. 203.411 Section 203.411 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...
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, 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, 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, 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...
Code of Federal Regulations, 2010 CFR
2010-07-01
... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Cash payments. 0.149 Section 0.149 Judicial Administration DEPARTMENT OF JUSTICE ORGANIZATION OF THE DEPARTMENT OF JUSTICE Authorizations With... maintenance of such accounts in accordance with the provisions set forth in the Treasury Financial Manual...
Cash Management Yields Many Maximum Returns.
ERIC Educational Resources Information Center
Traynham, William W., Jr
1987-01-01
Outlines the cash management program developed by the Orangeburg School District (SC) for the district's funds. They take bids from banks before deciding which bank to use for all their services, including an investment program. This new system has saved $30,000 in the first year. Sidebars tell how to shop for bank services and list technical…
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…
Electronic Cash Registers Are Valuable Tools.
ERIC Educational Resources Information Center
Gillespie, Edward, Jr.
1982-01-01
Electronic cash registers can perform functions ranging from simple change and tax computation to sophisticated merchandise accounting and inventory control information and records. The manager needs to outline the needed capabilities such as capacity, programmability, and servicing availability. User comments suggest varied benefits, uses, and…
Code of Federal Regulations, 2014 CFR
2014-01-01
... obtain full cash payment for customer purchases: (i) Within one payment period of the date: (A) Any... issuer has been purchased by the customer, provided: (1) The customer purchased the new security no more... payment. If a creditor purchases for or sells to a customer a security in a delivery against...
Code of Federal Regulations, 2013 CFR
2013-01-01
... obtain full cash payment for customer purchases: (i) Within one payment period of the date: (A) Any... issuer has been purchased by the customer, provided: (1) The customer purchased the new security no more... payment. If a creditor purchases for or sells to a customer a security in a delivery against...
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…
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.
Electronic Cash Registers Are Valuable Tools.
ERIC Educational Resources Information Center
Gillespie, Edward, Jr.
1982-01-01
Electronic cash registers can perform functions ranging from simple change and tax computation to sophisticated merchandise accounting and inventory control information and records. The manager needs to outline the needed capabilities such as capacity, programmability, and servicing availability. User comments suggest varied benefits, uses, and…
Hoskinson, Reed L [Rigby, ID; Svoboda, John M [Idaho Falls, ID; Bauer, William F [Idaho Falls, ID; Elias, Gracy [Idaho Falls, ID
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.
Comparison of Methods for Estimating Low Flow Characteristics of Streams
Tasker, Gary D.
1987-01-01
Four methods for estimating the 7-day, 10-year and 7-day, 20-year low flows for streams are compared by the bootstrap method. The bootstrap method is a Monte Carlo technique in which random samples are drawn from an unspecified sampling distribution defined from observed data. The nonparametric nature of the bootstrap makes it suitable for comparing methods based on a flow series for which the true distribution is unknown. Results show that the two methods based on hypothetical distribution (Log-Pearson III and Weibull) had lower mean square errors than did the G. E. P. Box-D. R. Cox transformation method or the Log-W. C. Boughton method which is based on a fit of plotting positions.
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
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
Meshless lattice Boltzmann method for the simulation of fluid flows.
Musavi, S Hossein; Ashrafizaadeh, Mahmud
2015-02-01
A meshless lattice Boltzmann numerical method is proposed. The collision and streaming operators of the lattice Boltzmann equation are separated, as in the usual lattice Boltzmann models. While the purely local collision equation remains the same, we rewrite the streaming equation as a pure advection equation and discretize the resulting partial differential equation using the Lax-Wendroff scheme in time and the meshless local Petrov-Galerkin scheme based on augmented radial basis functions in space. The meshless feature of the proposed method makes it a more powerful lattice Boltzmann solver, especially for cases in which using meshes introduces significant numerical errors into the solution, or when improving the mesh quality is a complex and time-consuming process. Three well-known benchmark fluid flow problems, namely the plane Couette flow, the circular Couette flow, and the impulsively started cylinder flow, are simulated for the validation of the proposed method. Excellent agreement with analytical solutions or with previous experimental and numerical results in the literature is observed in all the simulations. Although the computational resources required for the meshless method per node are higher compared to that of the standard lattice Boltzmann method, it is shown that for cases in which the total number of nodes is significantly reduced, the present method actually outperforms the standard lattice Boltzmann method.
Ten best resources on conditional cash transfers.
Marshall, Caroline; Hill, Peter S
2015-07-01
The world's economy is in a fragile state. Although cautiously recovering from a global recession, unemployment rates and poverty levels remain high. At the same time, food and fuel crises have resulted in skyrocketing commodity costs, straining household budgets even further than before. In the wake of these financial pressure points, there has been increased focus on social safety net programmes. More recently, Brazil's 'Bolsa Familia' conditional cash transfer (CCT) programme has celebrated its tenth-year anniversary, renewing focus on this particular aspect of social transfer programmes. This essay examines one particular aspect of these social safety net programmes: CCTs. CCT programmes are useful social programmes that have had demonstrable effects on many different populations. However, they are not a 'magic bullet' against poverty, and their image has suffered from unreasonable expectations of their impacts. This 10 best list is an ideal starting point from which a potential user can begin to understand CCTs. There remain significant gaps in the literature behind CCTs, with a particular need for much more research on emerging areas such as impacts on gender, long-term school and health outcomes, methods for increasing efficiency and adapting conditionalities within cultural contexts, among others. However, this list can function as a starting point from which the reader can gain an understanding and appreciation for what we believe to be one of the most innovative social programmes for addressing poverty worldwide. Published by Oxford University Press in association with The London School of Hygiene and Tropical Medicine © The Author 2014; all rights reserved.
Interactive method for computation of viscous flow with recirculation
NASA Technical Reports Server (NTRS)
Brandeis, J.; Rom, J.
1981-01-01
An interactive method is proposed for the solution of two-dimensional, laminar flow fields with identifiable regions of recirculation, such as the shear-layer-driven cavity flow. The method treats the flow field as composed of two regions, with an appropriate mathematical model adopted for each region. The shear layer is computed by the compressible boundary layer equations, and the slowly recirculating flow by the incompressible Navier-Stokes equations. The flow field is solved iteratively by matching the local solutions in the two regions. For this purpose a new matching method utilizing an overlap between the two computational regions is developed, and shown to be most satisfactory. Matching of the two velocity components, as well as the change in velocity with respect to depth is amply accomplished using the present approach, and the stagnation points corresponding to separation and reattachment of the dividing streamline are computed as part of the interactive solution. The interactive method is applied to the test problem of a shear layer driven cavity. The computational results are used to show the validity and applicability of the present approach.
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.
Interactive method for computation of viscous flow with recirculation
NASA Technical Reports Server (NTRS)
Brandeis, J.; Rom, J.
1981-01-01
An interactive method is proposed for the solution of two-dimensional, laminar flow fields with identifiable regions of recirculation, such as the shear-layer-driven cavity flow. The method treats the flow field as composed of two regions, with an appropriate mathematical model adopted for each region. The shear layer is computed by the compressible boundary layer equations, and the slowly recirculating flow by the incompressible Navier-Stokes equations. The flow field is solved iteratively by matching the local solutions in the two regions. For this purpose a new matching method utilizing an overlap between the two computational regions is developed, and shown to be most satisfactory. Matching of the two velocity components, as well as the change in velocity with respect to depth is amply accomplished using the present approach, and the stagnation points corresponding to separation and reattachment of the dividing streamline are computed as part of the interactive solution. The interactive method is applied to the test problem of a shear layer driven cavity. The computational results are used to show the validity and applicability of the present approach.
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.
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.
Mixed exhaust flow supersonic jet engine and method
Klees, G.W.
1993-06-08
A method of operating a supersonic jet engine installation is described comprising (a) providing an engine having a variable area air inlet means and an outlet to discharge engine exhaust; (b) providing a secondary air passageway means; (c) receiving ambient air in the air inlet means and providing the ambient air as primary air to the engine inlet and secondary air to the secondary air passageway means; (d) providing a mixing section having an inlet portion and an exit portion, utilizing the mixing section in directing the exhaust from the engine to primary convergent/divergent exit passageway segments, where the exhaust is discharged at supersonic velocity as primary flow components, and directing secondary air flow from the secondary air passageway means to secondary exit passageway segments which are interspersed with the primary segments and from which the secondary air is discharged at subsonic velocity as secondary flow components; and (e) providing an exhaust section to receive the primary and secondary flow components in a mixing region and causing the primary and secondary flow components to mix to create a supersonic mixed flow, the exhaust section having a variable area final nozzle through which the mixed flow is discharged.
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
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.
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.
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.
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.
Processing and analysis methods for transonic cavity flow
NASA Astrophysics Data System (ADS)
Loupy, G. J. M.; Barakos, G. N.
2017-07-01
This paper focuses on the localisation of noise sources in transonic cavity flows. Beamforming is used to estimate the pressure fluctuations inside a resonant transonic cavity, showing the localisation of the main sources of noise using an acoustic array and also combining it with a mean flow-field. The influence of the microphone array position, density, and shape is investigated. The presented method models the noise propagation with simple assumptions that are easily applicable to wind tunnel testing and may help localise the noise sources from complex geometries without intrusive methods.
An eddy viscosity calculation method for a turbulent duct flow
NASA Technical Reports Server (NTRS)
Antonia, R. A.; Bisset, D. K.; Kim, J.
1991-01-01
The mean velocity profile across a fully developed turbulent duct flow is obtained from an eddy viscosity relation combined with an empirical outer region wake function. Results are in good agreement with experiments and with direct numerical simulations in the same flow at two Reynolds numbers. In particular, the near-wall trend of the Reynolds shear stress and its variation with Reynolds number are similar to those of the simulations. The eddy viscosity method is more accurate than previous mixing length or implicit function methods.
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.
Finite element methods of studying mechanical factors in blood flow.
Davids, N
1981-01-01
This paper reviews some biomechanical analyses of blood flow in large arteries based on a general computer modeling using the finite element method. We study the following question: What is the role played by the interrelated factors of mechanical stress, flow irregularities, and diffusion through the endothelium on the etiology of atherosclerosis or the aggravation of vascular injury. It presents the computational features of the method and stresses the physiological significance of the results, such as the effect of geometric complexities, material nonlinearities, and non-Newtonian rheology of the blood. The specific mechanical and fluid dynamic factors analyzed are wall shear stress, flow profiles, and pressure variations. After simulating tubes of circular cross section, we apply the analysis to a number of physiological situations of significance, including blood flow in the entrance region, at bifurcations, in the annular region between an inserted catheter of varying diameter and the vessel. A model study of pulsatile flow in a 60 degree bifurcated channel of velocity profiles provided corroborative measurements of these processes with special emphasis on reversed or distributed flow conditions. The corresponding analysis was extended to the situation in which flow separates and reverses in the neighborhood of stagnation points. This required developing the nonlinear expression for the convective velocity change in the medium. A computer algorithm was developed to handle simultaneous effects of pressure and viscous forces on velocity change across the element and applied to the canine prebranch arterial segment. For mean physiological flow conditions, low shear stresses (0-10 dynes/cm2) are predicted near the wall in the diverging plane, higher values (50 dynes/cm2) along the converging sides of the wall. Backflow is predicted along the outer wall, pressure recovery prior to and into the branches, and a peak shear at the divider lip.
Calibration of base flow separation methods with streamflow conductivity.
Stewart, Mark; Cimino, Joseph; Ross, Mark
2007-01-01
The conductivity mass-balance (CMB) method can be used to calibrate analytical base flow separation methods. The principal CMB assumptions are base flow conductivity is equal to streamflow conductivity at lowest flows, runoff conductivity is equal to streamflow conductivity at highest flows, and base flow and runoff conductivities are assumed to be constants over the period of record. To test the CMB assumptions, fluid conductivities of ground water, surface runoff, and streamflow were measured during wet and dry conditions in a 12-km(2) stream basin. Ground water conductivities at wells varied an average of 6% from dry to wet conditions, while stream conductivities varied 58%. Shallow ground water conductivity varied significantly with distance from the stream, with lowest conductivities of 87 microS/cm near the divide, a maximum of 520 microS/cm 59 m from the stream, and 215 microS/cm 22 m from the stream. Runoff conductivities measured in three rain events remained nearly constant, with lower conductivities of 35 microS/cm near the divide and 50 microS/cm near the stream. The CMB method was applied to the records from 10 USGS stream-gauging stations in Texas, Kentucky, Georgia, and Florida to calibrate the USGS base flow separation technique, HYSEP, by varying the time parameter 2N*. There is a statistically significant relationship between basin areas and calibrated values of 2N*, expressed as N = 0.46A(0.44), with N in days and A in km(2). The widely accepted relationship N = 0.83A(0.2) is not valid for these basins. Other analytic methods can also be calibrated with the CMB method.
A sharp interface immersed boundary method for compressible viscous flows
NASA Astrophysics Data System (ADS)
Ghias, R.; Mittal, R.; Dong, H.
2007-07-01
An immersed boundary method for computing viscous, subsonic compressible flows with complex shaped stationary immersed boundaries is presented. The method employs a ghost-cell technique for imposing the boundary conditions on the immersed boundaries. The current approach leads to a sharp representation of the immersed boundaries, a property that is especially useful for flow simulations at high Reynolds numbers. Another unique feature of the method is that it can be applied on Cartesian as well as generalized body non-conformal curvilinear meshes. A mixed second-order central difference-QUICK scheme is used which allows a high degree of control over the numerical damping. A bilinear interpolation scheme used in conjunction with the ghost-cell approach results in second-order global as well as local spatial accuracy. The solver is parallelized for distributed memory platforms using domain decomposition and message passing interface (MPI) and salient features of the parallel algorithm are presented. The accuracy, fidelity and efficiency of the solver are examined by simulating flow past circular cylinders and airfoils and comparing against experimental data and other established results. Finally, we present results from a simulation of wing-tip flow at a relatively high Reynolds number in order to demonstrate the ability of the solver to model complex, non-canonical three-dimensional flows.
A simulated dye method for flow visualization with a computational model for blood flow.
Kim, T; Cheer, A Y; Dwyer, H A
2004-08-01
A numerical dye method for the visualization of unsteady three-dimensional flow calculations is introduced by coupling the unsteady convection-diffusion equation to the Navier-Stokes equation for mass and momentum. This system of equations is descretized using a finite volume projection-like algorithm with generalized coordinates and overset grids. A powerful pressure prediction method is used to accelerate the convergence of the Pressure Poisson equation. To demonstrate the visualization technique, blood flow through the aortic arch region and the three main arterial branches is computed using various Womersley numbers. In this technique, parcels of fluid are followed in time as a function of the cardiac cycle without having to track individual particles, which in turn aids us to better understand some important aspects of the three-dimensionality of the developing unsteady flow. Using this numerical dye method we analyze the strength of the cross flow during the cardiac cycle, the relationship between the penetration of blood into the aortic branches from its relative position in the ascending aortic region and the effects of the Womersley parameter. This technique can be very useful in the design and development of stents where the topology of the device would require understanding where the blood emanating from the heart ends up at the end of the cardiac cycle. Moreover, this method could be useful in investigating the influence of flow and geometry on the local introduction of medication.
Development of flow/steric field-flow fractionation as a routine process control method
Barman, B.N.
1988-08-30
Researchers studied the feasibility of using the Flow/Steric Field-Flow Fractionation (Flow/StFFF) method for the characterization of particulate materials with diameters in the 1-100 micrometers range. Studies on the optimization of the method for the separation and characterization of different size particulate samples, as well as on the role of the crossflow field and channel flowrate on the separation and resolution, were performed with a number of spherical polystyrene divinylbenzene latex standards and included in the report. Applicability of the method as a fast and reliable practical tool for industrial process control, particularly for grinding operations, was examined by analyzing a number of samples obtained by grinding. Examples of materials considered include coal, limestone and glass.
A flow cytometric method for platelet counting in platelet concentrates.
van der Meer, Pieter F; Karssing-van Leeuwen, Willy; Kurtz, Jim; Spengler, Hans-Peter; Blair, AbbeJane; Devine, Dana; Harrison, Paul; Lambrecht, Bernd; VandenBroeke, Tania; de Wildt, Janny; de Korte, Dirk
2012-01-01
The platelets (PLTs) in PLT concentrates are counted with hematology analyzers, but varying results among different hematology analyzers are observed, making comparisons very difficult. Due to the absence of red blood cells in PLT concentrates, the International Council for Standardization in Hematology (ICSH) reference method was modified to be used for PLT concentrates and validated in an international comparative study. Five PLT samples were shipped to eight participating centers of the Biomedical Excellence for Safer Transfusion (BEST) Collaborative and counted on the same day. PLTs were stained with fluorescein isothiocyanate-labeled anti-CD41a in tubes (TruCount, BD Biosciences), measured on a flow cytometer, and analyzed with a uniform template. These samples were also counted on 15 hematology analyzers. The ICSH method and newly developed BEST method yielded PLT counting results with less than 1% difference (not significant). The intercenter coefficient of variation (CV) of the BEST method was on average 6.3% versus 7.6% on average for hematology analyzers. The CV of individual hematology analyzers was on average 0.9%, which was considerably lower than for the flow cytometers with a mean of 3.7%. The BEST flow cytometric method has a smaller intercenter CV and a smaller center-to-center deviation from the group mean compared to hematology analyzers. Conversely, individual hematology analyzers are more precise than the flow cytometric method. Thus, the flow cytometric method provides a calibration tool to allow comparisons between centers, but there is no need to replace routine counting with hematology analyzers. © 2011 American Association of Blood Banks.
Methods for estimating low-flow statistics for Massachusetts streams
Ries, Kernell G.; Friesz, Paul J.
2000-01-01
Methods and computer software are described in this report for determining flow duration, low-flow frequency statistics, and August median flows. These low-flow statistics can be estimated for unregulated streams in Massachusetts using different methods depending on whether the location of interest is at a streamgaging station, a low-flow partial-record station, or an ungaged site where no data are available. Low-flow statistics for streamgaging stations can be estimated using standard U.S. Geological Survey methods described in the report. The MOVE.1 mathematical method and a graphical correlation method can be used to estimate low-flow statistics for low-flow partial-record stations. The MOVE.1 method is recommended when the relation between measured flows at a partial-record station and daily mean flows at a nearby, hydrologically similar streamgaging station is linear, and the graphical method is recommended when the relation is curved. Equations are presented for computing the variance and equivalent years of record for estimates of low-flow statistics for low-flow partial-record stations when either a single or multiple index stations are used to determine the estimates. The drainage-area ratio method or regression equations can be used to estimate low-flow statistics for ungaged sites where no data are available. The drainage-area ratio method is generally as accurate as or more accurate than regression estimates when the drainage-area ratio for an ungaged site is between 0.3 and 1.5 times the drainage area of the index data-collection site. Regression equations were developed to estimate the natural, long-term 99-, 98-, 95-, 90-, 85-, 80-, 75-, 70-, 60-, and 50-percent duration flows; the 7-day, 2-year and the 7-day, 10-year low flows; and the August median flow for ungaged sites in Massachusetts. Streamflow statistics and basin characteristics for 87 to 133 streamgaging stations and low-flow partial-record stations were used to develop the equations. The
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.
Fourier-Legendre spectral methods for incompressible channel flow
NASA Technical Reports Server (NTRS)
Zang, T. A.; Hussaini, M. Y.
1984-01-01
An iterative collocation technique is described for modeling implicit viscosity in three-dimensional incompressible wall bounded shear flow. The viscosity can vary temporally and in the vertical direction. Channel flow is modeled with a Fourier-Legendre approximation and the mean streamwise advection is treated implicitly. Explicit terms are handled with an Adams-Bashforth method to increase the allowable time-step for calculation of the implicit terms. The algorithm is applied to low amplitude unstable waves in a plane Poiseuille flow at an Re of 7500. Comparisons are made between results using the Legendre method and with Chebyshev polynomials. Comparable accuracy is obtained for the perturbation kinetic energy predicted using both discretizations.
The impact of Mexico's conditional cash transfer programme, Oportunidades, on birthweight
Barber, Sarah L.; Gertler, Paul J.
2010-01-01
Summary Objectives To evaluate the impact of Oportunidades, a large-scale, conditional cash transfer programme in Mexico, on birthweight. The programme provides cash transfers to low-income, rural households in Mexico, conditional on accepting nutritional supplements health education, and health care. Methods The primary analyses used retrospective reports from 840 women in poor rural communities participating in an effectiveness study and randomly assigned to incorporation into the programme in 1998 or 1999 across seven Mexican states. Pregnant women in participating households received nutrition supplements and health care, and accepted cash transfers. Using multivariate and instrumental variable analyses, we estimated the impact of the programme on birthweight in grams and low birthweight (<2500 g), receipt of any pre-natal care, and number of pre-natal visits. Results Oportunidades beneficiary status was associated with 127.3 g higher birthweight among participating women and a 4.6 percentage point reduction in low birthweight. Conclusion The Oportunidades conditional cash transfer programme improved birthweight outcomes. This finding is relevant to countries implementing conditional cash transfer programmes. PMID:18983270
Time-derivative preconditioning method for multicomponent flow
NASA Astrophysics Data System (ADS)
Housman, Jeffrey Allen
A time-derivative preconditioned system of equations suitable for the numerical simulation of single component and multicomponent inviscid flows at all speeds is formulated. The system is shown to be hyperbolic in time and remain well-posed at low Mach numbers, allowing an efficient time marching solution strategy to be utilized from transonic to incompressible flow speeds. For multicomponent flow at low speed, a preconditioned nonconservative discretization scheme is described which preserves pressure and velocity equilibrium across fluid interfaces, handles sharp liquid/gas interfaces with large density ratios, while remaining well-conditioned for time marching methods. The method is then extended to transonic and supersonic flows using a hybrid conservative/nonconservative formulation which retains the pressure/velocity equilibrium property and converges to the correct weak solution when shocks are present. In order to apply the proposed model to complex flow applications, the overset grid methodology is used where the equations are transformed to a nonorthogonal curvilinear coordinate system and discretized on structured body-fitted curvilinear grids. The multicomponent model and its extension to homogeneous multiphase mixtures is discussed and the hyperbolicity of the governing equations is demonstrated. Low Mach number perturbation analysis is then performed on the system of equations and a local time-derivative preconditioning matrix is derived allowing time marching numerical methods to remain efficient at low speeds. Next, a particular time marching numerical method is presented along with three discretization schemes for the convective terms. These include a conservative preconditioned Roe type method, a nonconservative preconditioned Split Coefficient Matrix (SCM) method, and hybrid formulation which combines the conservative and nonconservative schemes using a simple switching function. A characteristic boundary treatment which includes time
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.
The numerical methods for the fluid flow of UCMCWS
Zhang Wenfu; Li Hui; Zhu Shuquan; Wang Zuna
1997-12-31
As an alternative for diesel oil for internal combustion engines, the fluid flow state of Ultra Clean Micronized Coal-Water Slurry (UCMCWS) in mini pipe and nozzle of a diesel engine must be known. In the laboratory three kinds of UCMCWS have been made with coal containing less than 0.8% ash, viscosity less than 600 mPa.s and concentration between 50% and 56%. Because the UCMCWS is a non-Newtonian fluid, there are no analytical resolution for pipe flow, especially in inlet and outlet sections. In this case using the numerical methods to research the flow state of UCMCWS is a useful method. Using the method of finite element, the flow state of UCMCWS in inlet and outlet sections (similar to a nozzle) have been studied. The distribution of velocity at different pressures of UCMCWS in outlet and inlet sections have been obtained. The result of the numerical methods is the efficient base for the pipe and nozzle design.
Numerical methods and calculations for droplet flow, heating and ignition
NASA Technical Reports Server (NTRS)
Dwyer, H. A.; Sanders, B. R.; Dandy, D.
1982-01-01
A numerical method was devised and employed to solve a variety of problems related to liquid droplet combustion. The basic transport equations of mass, momentum and energy were formulated in terms of generalized nonorthogonal coordinates, which allows for adaptive griding and arbitrary particle shape. Example problems are solved for internal droplet heating, droplet ignition and high Reynolds number flow over a droplet.
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
Lattice Boltzmann method for linear oscillatory noncontinuum flows
NASA Astrophysics Data System (ADS)
Shi, Yong; Yap, Ying Wan; Sader, John E.
2014-03-01
Oscillatory gas flows are commonly generated by micro- and nanoelectromechanical systems. Due to their small size and high operating frequencies, these devices often produce noncontinuum gas flows. Theoretical analysis of such flows requires solution of the unsteady Boltzmann equation, which can present a formidable challenge. In this article, we explore the applicability of the lattice Boltzmann (LB) method to such linear oscillatory noncontinuum flows; this method is derived from the linearized Boltzmann Bhatnagar-Gross-Krook (BGK) equation. We formulate four linearized LB models in the frequency domain, based on Gaussian-Hermite quadratures of different algebraic precision (AP). The performance of each model is assessed by comparison to high-accuracy numerical solutions to the linearized Boltzmann-BGK equation for oscillatory Couette flow. The numerical results demonstrate that high even-order LB models provide superior performance over the greatest noncontinuum range. Our results also highlight intrinsic deficiencies in the current LB framework, which is incapable of capturing noncontinuum behavior at high oscillation frequencies, regardless of quadrature AP and the Knudsen number.
Multicomponent-flow analyses by multimode method of characteristics
Lai, Chintu
1994-01-01
For unsteady open-channel flows having N interacting unknown variables, a system of N mutually independent, partial differential equations can be used to describe the flow-field. The system generally belongs to marching-type problems and permits transformation into characteristic equations that are associated with N distinct characteristics directions. Because characteristics can be considered 'wave' or 'disturbance' propagation, a fluvial system so described can be viewed as adequately definable using these N component waves. A numerical algorithm to solve the N families of characteristics can then be introduced for formulation of an N-component flow-simulation model. The multimode method of characteristics (MMOC), a new numerical scheme that has a combined capacity of several specified-time-interval (STI) schemes of the method of characteristics, makes numerical modeling of such N-component riverine flows feasible and attainable. Merging different STI schemes yields different kinds of MMOC schemes, for which two kinds are displayed herein. With the MMOC, each characteristics is dynamically treated by an appropriate numerical mode, which should lead to an effective and suitable global simulation, covering various types of unsteady flow. The scheme is always linearly stable and its numerical accuracy can be systematically analyzed. By increasing the N value, one can develop a progressively sophisticated model that addresses increasingly complex river-mechanics problems.
Lattice Boltzmann method for linear oscillatory noncontinuum flows.
Shi, Yong; Yap, Ying Wan; Sader, John E
2014-03-01
Oscillatory gas flows are commonly generated by micro- and nanoelectromechanical systems. Due to their small size and high operating frequencies, these devices often produce noncontinuum gas flows. Theoretical analysis of such flows requires solution of the unsteady Boltzmann equation, which can present a formidable challenge. In this article, we explore the applicability of the lattice Boltzmann (LB) method to such linear oscillatory noncontinuum flows; this method is derived from the linearized Boltzmann Bhatnagar-Gross-Krook (BGK) equation. We formulate four linearized LB models in the frequency domain, based on Gaussian-Hermite quadratures of different algebraic precision (AP). The performance of each model is assessed by comparison to high-accuracy numerical solutions to the linearized Boltzmann-BGK equation for oscillatory Couette flow. The numerical results demonstrate that high even-order LB models provide superior performance over the greatest noncontinuum range. Our results also highlight intrinsic deficiencies in the current LB framework, which is incapable of capturing noncontinuum behavior at high oscillation frequencies, regardless of quadrature AP and the Knudsen number.
Time spectral method for rotorcraft flow with vorticity confinement
NASA Astrophysics Data System (ADS)
Butsuntorn, Nawee
2008-10-01
This thesis shows that simulation of helicopter flows can adhere to engineering accuracy without the need of massive computing resources or long turnaround time by choosing an alternative framework for rotorcraft simulation. The method works in both hovering and forward flight regimes. The new method has shown to be more computationally efficient and sufficiently accurate. By utilizing the periodic nature of the rotorcraft flow field, the Fourier based Time Spectral method lends itself to the problem and significantly increases the rate of convergence compared to traditional implicit time integration schemes such as the second order backward difference formula (BDF). A Vorticity Confinement method has been explored and has been shown to work well in subsonic and transonic simulations. Vortical structure can be maintained after long distances without resorting to the traditional mesh refinement technique.
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.
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.
Modeling electrokinetic flow by Lagrangian particle-based method
NASA Astrophysics Data System (ADS)
Pan, Wenxiao; Kim, Kyungjoo; Perego, Mauro; Tartakovsky, Alexandre; Parks, Mike
2015-11-01
This work focuses on mathematical models and numerical schemes based on Lagrangian particle-based method that can effectively capture mesoscale multiphysics (hydrodynamics, electrostatics, and advection-diffusion) associated in applications of micro-/nano-transport and technology. The order of accuracy is significantly improved for particle-based method with the presented implicit consistent numerical scheme. Specifically, we show simulation results on electrokinetic flows and microfluidic mixing processes in micro-/nano-channel and through semi-permeable porous structures.
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.
Adaptive Spectral Estimation Methods in Color Flow Imaging.
Karabiyik, Yucel; Ekroll, Ingvild Kinn; Eik-Nes, Sturla H; Avdal, Jorgen; Lovstakken, Lasse
2016-11-01
Clutter rejection for color flow imaging (CFI) remains a challenge due to either a limited amount of temporal samples available or nonstationary tissue clutter. This is particularly the case for interleaved CFI and B-mode acquisitions. Low velocity blood signal is attenuated along with the clutter due to the long transition band of the available clutter filters, causing regions of biased mean velocity estimates or signal dropouts. This paper investigates how adaptive spectral estimation methods, Capon and blood iterative adaptive approach (BIAA), can be used to estimate the mean velocity in CFI without prior clutter filtering. The approach is based on confining the clutter signal in a narrow spectral region around the zero Doppler frequency while keeping the spectral side lobes below the blood signal level, allowing for the clutter signal to be removed by thresholding in the frequency domain. The proposed methods are evaluated using computer simulations, flow phantom experiments, and in vivo recordings from the common carotid and jugular vein of healthy volunteers. Capon and BIAA methods could estimate low blood velocities, which are normally attenuated by polynomial regression filters, and may potentially give better estimation of mean velocities for CFI at a higher computational cost. The Capon method decreased the bias by 81% in the transition band of the used polynomial regression filter for small packet size ( N=8 ) and low SNR (5 dB). Flow phantom and in vivo results demonstrate that the Capon method can provide color flow images and flow profiles with lower variance and bias especially in the regions close to the artery walls.
Adaptive Spectral Estimation Methods in Color Flow Imaging.
Karabiyik, Yucel; Ekroll, Ingvild Kinn; Eik-Nes, Sturla; Avdal, Jorgen; Lovstakken, Lasse
2016-07-28
Clutter rejection for color flow imaging (CFI) remains a challenge due to either limited amount of temporal samples available or non-stationary tissue clutter. This is particularly the case for interleaved CFI and B-mode acquisitions. Low velocity blood signal is attenuated along with the clutter due to the long transition band of the available clutter filters, causing regions of biased mean velocity estimates or signal dropouts. This work investigates how adaptive spectral estimation methods, the Capon and BIAA, can be used to estimate the mean velocity in CFI without prior clutter filtering. The approach is based on confining the clutter signal in a narrow spectral region around the zero Doppler frequency while keeping the spectral side lobes below the blood signal level, allowing for the clutter signal to be removed by thresholding in the frequency domain. The proposed methods are evaluated using computer simulations, flow phantom experiments and in-vivo recordings from the common carotid and jugular vein of healthy volunteers. Capon and BIAA methods could estimate low blood velocities which are normally attenuated by polynomial regression filters, and may potentially give better estimation of mean velocities for CFI at a higher computational cost. The Capon method decreased the bias by 81% in the transition band of the used polynomial regression filter for small packet size (N=8) and low SNR (5 dB). Flow phantom and invivo results demonstrate that the Capon method can provide color flow images and flow profiles with lower variance and bias especially in the regions close to the artery walls.
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.
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 cell-centered ICE method for multiphase flow simulations
Kashiwa, B.A.; Padial, N.T.; Rauenzahn, R.M.; VanderHeyden, W.B.
1993-12-01
The Implicit Continuous-fluid Eulerian (ICE) method is a finite-volume scheme that is stable for any value of the Courant number based on the sound speed. In the incompressible limit, the ICE method becomes essentially identical to the Marker and Cell (MAC) method, so the two schemes are closely related. In this article, the classical ICE method is extended to multiple interpenetrating phases, and employed with a single control volume (nonstaggered) mesh framework. The incompressible limit is preserved, so that problems involving equations of state, or those exhibiting constant material densities, can be addressed with the same computer code. The scheme reduces properly to a single-fluid method, enabling benchmarking using well-known test cases. Thus, the numerical issues focus only on those aspects unique to problems having multiple density, velocity and temperature fields. The discussion begins with a derivation of the exact, ensemble-averaged equations. Examples of the most basic closures axe given, and the well-posedness of the equations is demonstrated. The numerical method is described in operator notation, and the discretization is sketched. The flow patterns in a bubble column are computed as an incompressible flow example. For a compressible flow example, the expansion and compression of a bubble formed by high-explosive gases under water is shown. In each case, comparison to experimental data is made.
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.
High Order Filter Methods for Shock/Turbulence MHD Flows
NASA Technical Reports Server (NTRS)
Yee, H. C.; Sjoegreen, Bjoern
2003-01-01
Low-dissipative high order filter finite difference methods for shock/turbulence/combustion compressible viscous MHD flows has been constructed. Several variants of the filter approach that cater to different flow types are proposed. These filters provide a natural and efficient way for the minimization of the divergence of the magnetic field (del (raided dot) B) numerical error in the sense that no standard divergence cleaning is required. For certain 2-D MHD test problems, divergence free preservation of the magnetic fields of these filter schemes has been achieved.
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.
Using mixed methods to identify factors influencing patient flow.
Van Vaerenbergh, Cindy
2009-11-01
An effective method of identifying operational factors that influence patient flow can potentially lead to improvements and thus have huge benefits on the efficiency of hospital departments. This paper presents a new inductive mixed-method approach to identify operational factors that influence patient flow through an accident and emergency (A&E) department. Preliminary explorative observations were conducted, followed by semi-structured interviews with key stakeholders. A questionnaire survey of all medical, nursing, porter and clerical staff was then conducted. The observations provided factors for further exploration: skill-mix, long working hours, equipment availability, lack of orientation programmes, inefficient IT use and issues regarding communication structures. Interviewees highlighted several factors, including availability of medical supervision and senior nursing staff, nursing documentation issues, lack of morale due to overcrowding, personality differences and factors relating to the department layout. The questionnaire respondents strongly supported the importance of the previously identified factors. This paper demonstrates an effective mixed-method approach that can be replicated by other health-care managers to identify factors influencing patient flow. Further benefits include increased volume and quality of data, increased staff awareness for the influence of internal factors on patient flow and enhancing the evidence base for future decision making when prioritizing A&E projects.
Intrusive Method for Uncertainty Quantification in a Multiphase Flow Solver
NASA Astrophysics Data System (ADS)
Turnquist, Brian; Owkes, Mark
2016-11-01
Uncertainty quantification (UQ) is a necessary, interesting, and often neglected aspect of fluid flow simulations. To determine the significance of uncertain initial and boundary conditions, a multiphase flow solver is being created which extends a single phase, intrusive, polynomial chaos scheme into multiphase flows. Reliably estimating the impact of input uncertainty on design criteria can help identify and minimize unwanted variability in critical areas, and has the potential to help advance knowledge in atomizing jets, jet engines, pharmaceuticals, and food processing. Use of an intrusive polynomial chaos method has been shown to significantly reduce computational cost over non-intrusive collocation methods such as Monte-Carlo. This method requires transforming the model equations into a weak form through substitution of stochastic (random) variables. Ultimately, the model deploys a stochastic Navier Stokes equation, a stochastic conservative level set approach including reinitialization, as well as stochastic normals and curvature. By implementing these approaches together in one framework, basic problems may be investigated which shed light on model expansion, uncertainty theory, and fluid flow in general. NSF Grant Number 1511325.
Anisotropic adaptive finite element method for modelling blood flow.
Müller, J; Sahni, O; Li, X; Jansen, K E; Shephard, M S; Taylor, C A
2005-10-01
In this study, we present an adaptive anisotropic finite element method (FEM) and demonstrate how computational efficiency can be increased when applying the method to the simulation of blood flow in the cardiovascular system. We use the SUPG formulation for the transient 3D incompressible Navier-Stokes equations which are discretised by linear finite elements for both the pressure and the velocity field. Given the pulsatile nature of the flow in blood vessels we have pursued adaptivity based on the average flow over a cardiac cycle. Error indicators are derived to define an anisotropic mesh metric field. Mesh modification algorithms are used to anisotropically adapt the mesh according to the desired size field. We demonstrate the efficiency of the method by first applying it to pulsatile flow in a straight cylindrical vessel and then to a porcine aorta with a stenosis bypassed by a graft. We demonstrate that the use of an anisotropic adaptive FEM can result in an order of magnitude reduction in computing time with no loss of accuracy compared to analyses obtained with uniform meshes.
Thermodynamical effects and high resolution methods for compressible fluid flows
NASA Astrophysics Data System (ADS)
Li, Jiequan; Wang, Yue
2017-08-01
One of the fundamental differences of compressible fluid flows from incompressible fluid flows is the involvement of thermodynamics. This difference should be manifested in the design of numerical schemes. Unfortunately, the role of entropy, expressing irreversibility, is often neglected even though the entropy inequality, as a conceptual derivative, is verified for some first order schemes. In this paper, we refine the GRP solver to illustrate how the thermodynamical variation is integrated into the design of high resolution methods for compressible fluid flows and demonstrate numerically the importance of thermodynamic effects in the resolution of strong waves. As a by-product, we show that the GRP solver works for generic equations of state, and is independent of technical arguments.
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.
Synthetic-Eddy Method for Urban Atmospheric Flow Modelling
NASA Astrophysics Data System (ADS)
Pavlidis, D.; Gorman, G. J.; Gomes, J. L. M. A.; Pain, C. C.; Apsimon, H.
2010-08-01
The computational fluid dynamics code Fluidity, with anisotropic mesh adaptivity, is used as a multi-scale obstacle-accommodating meteorological model. A novel method for generating realistic inlet boundary conditions based on the view of turbulence as a superposition of synthetic eddies is adopted. It is able to reproduce prescribed first-order and second-order one-point statistics and turbulence length scales. The aim is to simulate an urban boundary layer. The model is validated against two standard benchmark tests: a plane channel flow numerical simulation and a flow past a cube physical simulation. The performed large-eddy simulations are in good agreement with both reference models giving confidence that the model can be used to successfully simulate urban atmospheric flows.
Vortex flows in the solar chromosphere. I. Automatic detection method
NASA Astrophysics Data System (ADS)
Kato, Y.; Wedemeyer, S.
2017-05-01
Solar "magnetic tornadoes" are produced by rotating magnetic field structures that extend from the upper convection zone and the photosphere to the corona of the Sun. Recent studies show that these kinds of rotating features are an integral part of atmospheric dynamics and occur on a large range of spatial scales. A systematic statistical study of magnetic tornadoes is a necessary next step towards understanding their formation and their role in mass and energy transport in the solar atmosphere. For this purpose, we develop a new automatic detection method for chromospheric swirls, meaning the observable signature of solar tornadoes or, more generally, chromospheric vortex flows and rotating motions. Unlike existing studies that rely on visual inspections, our new method combines a line integral convolution (LIC) imaging technique and a scalar quantity that represents a vortex flow on a two-dimensional plane. We have tested two detection algorithms, based on the enhanced vorticity and vorticity strength quantities, by applying them to three-dimensional numerical simulations of the solar atmosphere with CO5BOLD. We conclude that the vorticity strength method is superior compared to the enhanced vorticity method in all aspects. Applying the method to a numerical simulation of the solar atmosphere reveals very abundant small-scale, short-lived chromospheric vortex flows that have not been found previously by visual inspection.
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
Method for Studying Microbial Biofilms in Flowing-Water Systems
Pedersen, Karsten
1982-01-01
A method for the study of microbial biofilms in flowing-water systems was developed with special reference to the flow conditions in electrochemical concentration cells. Seawater was circulated in a semiclosed flow system through biofilm reactors (3 cm s−1) with microscope cover slips arranged in lamellar piles parallel with the flow. At fixed time intervals cover slips with their biofilm were removed from the pile, stained with crystal violet, and mounted on microscope slides. The absorbances of the slides were measured at 590 nm and plotted against time to give microbial biofilm development. From calibration experiments a staining time of 1 min and a rinse time of 10 min in a tap water flow (3 cm s−1) were considered sufficient. When an analysis of variance was performed on biofilm development data, 78% of the total variance was found to be due to random natural effects; the rest could be explained by experimental effects. The absorbance values correlated well with protein N, dry weight, and organic weight in two biofilm experiments, one with a biofilm with a high (75%) and one with a low (∼25%, normal) inorganic content. Comparisons of regression lines revealed that the absorbance of the stained biofilms was an estimate closely related to biofilm dry weight. PMID:16345929
Flow visualisation of downhill skiers using the lattice Boltzmann method
NASA Astrophysics Data System (ADS)
Asai, Takeshi; Hong, Sungchan; Ijuin, Koichi
2017-03-01
In downhill alpine skiing, skiers often exceed speeds of 120 km h-1, with air resistance substantially affecting the overall race times. To date, studies on air resistance in alpine skiing have used wind tunnels and actual skiers to examine the relationship between the gliding posture and magnitude of drag and for the design of skiing equipment. However, these studies have not revealed the flow velocity distribution and vortex structure around the skier. In the present study, computational fluid dynamics are employed with the lattice Boltzmann method to derive the relationship between total drag and the flow velocity around a downhill skier in the full-tuck position. Furthermore, the flow around the downhill skier is visualised, and its vortex structure is examined. The results show that the total drag force in the downhill skier model is 27.0 N at a flow velocity of 15 m s-1, increasing to 185.8 N at 40 m s-1. From analysis of the drag distribution and the flow profile, the head, upper arms, lower legs, and thighs (including buttocks) are identified as the major sources of drag on a downhill skier. Based on these results, the design of suits and equipment for reducing the drag from each location should be the focus of research and development in ski equipment. This paper describes a pilot study that introduces undergraduate students of physics or engineering into this research field. The results of this study are easy to understand for undergraduate students.
Numerical Methods and Simulations of Complex Multiphase Flows
NASA Astrophysics Data System (ADS)
Brady, Peter
Multiphase flows are an important part of many natural and technological phenomena such as ocean-air coupling (which is important for climate modeling) and the atomization of liquid fuel jets in combustion engines. The unique challenges of multiphase flow often make analytical solutions to the governing equations impossible and experimental investigations very difficult. Thus, high-fidelity numerical simulations can play a pivotal role in understanding these systems. This dissertation describes numerical methods developed for complex multiphase flows and the simulations performed using these methods. First, the issue of multiphase code verification is addressed. Code verification answers the question "Is this code solving the equations correctly?" The method of manufactured solutions (MMS) is a procedure for generating exact benchmark solutions which can test the most general capabilities of a code. The chief obstacle to applying MMS to multiphase flow lies in the discontinuous nature of the material properties at the interface. An extension of the MMS procedure to multiphase flow is presented, using an adaptive marching tetrahedron style algorithm to compute the source terms near the interface. Guidelines for the use of the MMS to help locate coding mistakes are also detailed. Three multiphase systems are then investigated: (1) the thermocapillary motion of three-dimensional and axisymmetric drops in a confined apparatus, (2) the flow of two immiscible fluids completely filling an enclosed cylinder and driven by the rotation of the bottom endwall, and (3) the atomization of a single drop subjected to a high shear turbulent flow. The systems are simulated numerically by solving the full multiphase Navier-Stokes equations coupled to the various equations of state and a level set interface tracking scheme based on the refined level set grid method. The codes have been parallelized using MPI in order to take advantage of today's very large parallel computational
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.
A conservative method for hydrostatic flow in isentropic coordinates
NASA Astrophysics Data System (ADS)
Peeters, B.; Bokhove, O.; Frank, J.
2010-05-01
Although our climate is ultimately driven by (nonuniform) solar heating, many aspects of the flow can be understood qualitatively from forcing-free and frictionless dynamics. In the limit of zero forcing and dissipation, our weather system falls under the realm of Hamiltonian fluid dynamics and the flow conserves potential vorticity (PV), energy and phase-space structure. We have found a conservative numerical scheme for a hydrostatic atmosphere based on a mixed Eulerian-Lagrangian approach, the so-called parcel formulation [1]. For adiabatic flow, the entropy is materially conserved. Under stable stratifications, we introduce isentropic coordinates to simplify the governing equations. The entropic direction is discretized using finite elements. The discretization of horizontal Lagrangian label space (from infinitesimal fluid parcels to discrete fluid particles) yields a discrete Poisson bracket. New is that we apply the Hamiltonian Particle-Mesh method [2], and view the potential as an Eulerian function, reconstructed from the particle data. The use of an Eulerian grid makes the method more efficient and stable. The Hamiltonian consists of a Lagrangian kinetic energy and an Eulerian potential energy. The discrete system of ODE's is thus a Hamiltonian system conserving mass, PV, energy and phase-space structure. If we incorporate a symplectic time integrator, the resulting fully discrete system conserves energy approximately without any drift in energy. Several challenging (nonlinear) solutions will be tested, such a flow over a rising bump. Also, preliminary results for bottom-intersecting isentropes will be demonstrated. REFERENCES [1] O. Bokhove and M. Oliver, Parcel Eulerian-Lagrangian fluid dynamics for rotating geophysical flows, Proc. Roy. Soc. A. 462, pp. 2563-2573 (2006) [2] J. Frank, G. Gottwald, S. Reich, A Hamiltonian particle-mesh method for the rotating shallow-water equations, Lecture Notes in Computational Science and Engineering, Vol. 26, Springer
A spectral boundary integral method for flowing blood cells
NASA Astrophysics Data System (ADS)
Zhao, Hong; Isfahani, Amir H. G.; Olson, Luke N.; Freund, Jonathan B.
2010-05-01
A spectral boundary integral method for simulating large numbers of blood cells flowing in complex geometries is developed and demonstrated. The blood cells are modeled as finite-deformation elastic membranes containing a higher viscosity fluid than the surrounding plasma, but the solver itself is independent of the particular constitutive model employed for the cell membranes. The surface integrals developed for solving the viscous flow, and thereby the motion of the massless membrane, are evaluated using an O(NlogN) particle-mesh Ewald (PME) approach. The cell shapes, which can become highly distorted under physiologic conditions, are discretized with spherical harmonics. The resolution of these global basis functions is, of course, excellent, but more importantly they facilitate an approximate de-aliasing procedure that stabilizes the simulations without adding any numerical dissipation or further restricting the permissible numerical time step. Complex geometry no-slip boundaries are included using a constraint method that is coupled into an implicit system that is solved as part of the time advancement routine. The implementation is verified against solutions for axisymmetric flows reported in the literature, and its accuracy is demonstrated by comparison against exact solutions for relaxing surface deformations. It is also used to simulate flow of blood cells at 30% volume fraction in tubes between 4.9 and 16.9 μm in diameter. For these, it is shown to reproduce the well-known non-monotonic dependence of the effective viscosity on the tube diameter.
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.
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
Smoothed particle hydrodynamics method for evaporating multiphase flows
NASA Astrophysics Data System (ADS)
Yang, Xiufeng; Kong, Song-Charng
2017-09-01
The smoothed particle hydrodynamics (SPH) method has been increasingly used for simulating fluid flows; however, its ability to simulate evaporating flow requires significant improvements. This paper proposes an SPH method for evaporating multiphase flows. The present SPH method can simulate the heat and mass transfers across the liquid-gas interfaces. The conservation equations of mass, momentum, and energy were reformulated based on SPH, then were used to govern the fluid flow and heat transfer in both the liquid and gas phases. The continuity equation of the vapor species was employed to simulate the vapor mass fraction in the gas phase. The vapor mass fraction at the interface was predicted by the Clausius-Clapeyron correlation. An evaporation rate was derived to predict the mass transfer from the liquid phase to the gas phase at the interface. Because of the mass transfer across the liquid-gas interface, the mass of an SPH particle was allowed to change. Alternative particle splitting and merging techniques were developed to avoid large mass difference between SPH particles of the same phase. The proposed method was tested by simulating three problems, including the Stefan problem, evaporation of a static drop, and evaporation of a drop impacting a hot surface. For the Stefan problem, the SPH results of the evaporation rate at the interface agreed well with the analytical solution. For drop evaporation, the SPH result was compared with the result predicted by a level-set method from the literature. In the case of drop impact on a hot surface, the evolution of the shape of the drop, temperature, and vapor mass fraction were predicted.
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.
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.
Silver and gold enhancement methods for lateral flow immunoassays.
Rodríguez, Myriam Oliveira; Covián, Lucía Blanco; García, Agustín Costa; Blanco-López, Maria Carmen
2016-01-01
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. Copyright © 2015 Elsevier B.V. All rights reserved.
Aerosol flow reactor method for synthesis of drug nanoparticles.
Eerikäinen, Hannele; Watanabe, Wiwik; Kauppinen, Esko I; Ahonen, P Petri
2003-05-01
An aerosol flow reactor method, a one-step continuous process to produce nanometer-sized drug particles with unimodal size distribution, was developed. This method involves first dissolving the drug material in question into a suitable solvent, which is then followed by atomising the solution as fine droplets into carrier gas. A heated laminar flow reactor tube is used to evaporate the solvent, and solid drug nanoparticles are formed. In this study, the effect of drying temperature on the particle size and morphology was examined. A glucocorticosteroid used for asthma therapy, beclomethasone dipropionate, was selected as an experimental model drug. The geometric number mean particle diameter increases significantly with increasing reactor temperatures due to formation of hollow nanoparticles. Above 160 degrees C, however, further increase in temperature results in decreasing particle size. The produced nanoparticles are spherical and show smooth surfaces at all studied experimental conditions.
Preconditioned lattice-Boltzmann method for steady flows
NASA Astrophysics Data System (ADS)
Guo, Zhaoli; Zhao, T. S.; Shi, Yong
2004-12-01
In this paper we propose a preconditioned lattice Boltzmann (LB) method for steady incompressible flows. For steady flows, the macroscopic equations derived from this LB model are equivalent to those from the standard LB model, but with an improved eigenvalue system. The proposed model can be viewed as an explicit solver for preconditioned compressible Navier-Stokes equations. Linear stability analysis is performed and the results show that the stability of the model is the same as that of the standard LB model for low Mach numbers. The proposed model retains the structure of the standard LB model and, hence, possesses all the advantages. Numerical tests show that the convergence rate can be enhanced as much as an order of magnitude compared to the standard lattice Boltzmann method. The accuracy of the solutions is improved as well.
Mexico’s conditional cash transfer programme increases cesarean section rates among the rural poor
2010-01-01
Background: Caesarean section rates are increasing in Mexico and Latin America. This study evaluates the impact of a large-scale, conditional cash transfer programme in Mexico on caesarean section rates. The programme provides cash transfers to participating low income, rural households in Mexico conditional on accepting health care and nutrition supplements. Methods: The primary analyses uses retrospective reports from 979 women in poor rural communities participating in an effectiveness study and randomly assigned to incorporation into the programme in 1998 or 1999 across seven Mexican states. Using multivariate and instrumental variable analyses, we estimate the impact of the programme on caesarean sections and predict the adjusted mean rates by clinical setting. Programme participation is measured by beneficiary status, programme months and cash transfers. Results: More than two-thirds of poor rural women delivered in a health facility. Beneficiary status is associated with a 5.1 percentage point increase in caesarean rates; this impact increases to 7.5 percentage points for beneficiaries enrolled in the programme for ≥6 months before delivery. Beneficiaries had significantly higher caesarean delivery rates in social security facilities (24.0 compared with 5.6% among non-beneficiaries) and in other government facilities (19.3 compared with 9.5%). Conclusion: The Oportunidades conditional cash transfer programme is associated with higher caesarean section rates in social security and government health facilities. This effect appears to be driven by the increases in disposable income from the cash transfer. These findings are relevant to other countries implementing conditional cash transfer programmes and health care requirements. PMID:19933778
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.
High speed inviscid compressible flow by the finite element method
NASA Technical Reports Server (NTRS)
Zienkiewicz, O. C.; Loehner, R.; Morgan, K.
1984-01-01
The finite element method and an explicit time stepping algorithm which is based on Taylor-Galerkin schemes with an appropriate artificial viscosity is combined with an automatic mesh refinement process which is designed to produce accurate steady state solutions to problems of inviscid compressible flow in two dimensions. The results of two test problems are included which demonstrate the excellent performance characteristics of the proposed procedures.
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.
Development of Methods for Diagnostics of Discharges in Supersonic Flows
2004-03-01
flow, diagnostic methods, electric probe, measurement circuit, propane-air mixture, ignition. Participating Institution : Department of...932-88-20 E-mail: dean@phys.msu.su /ershov@ph-elec.phys.msu.su Partner: The European Office of Aerospace Research and Development (EOARD) Adress...of flight . The gas discharges of a various type can be the perspective tool of the decision of this problem. The definition of the most effective
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.
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…
Lagrangian transported MDF methods for compressible high speed flows
NASA Astrophysics Data System (ADS)
Gerlinger, Peter
2017-06-01
This paper deals with the application of thermochemical Lagrangian MDF (mass density function) methods for compressible sub- and supersonic RANS (Reynolds Averaged Navier-Stokes) simulations. A new approach to treat molecular transport is presented. This technique on the one hand ensures numerical stability of the particle solver in laminar regions of the flow field (e.g. in the viscous sublayer) and on the other hand takes differential diffusion into account. It is shown in a detailed analysis, that the new method correctly predicts first and second-order moments on the basis of conventional modeling approaches. Moreover, a number of challenges for MDF particle methods in high speed flows is discussed, e.g. high cell aspect ratio grids close to solid walls, wall heat transfer, shock resolution, and problems from statistical noise which may cause artificial shock systems in supersonic flows. A Mach 2 supersonic mixing channel with multiple shock reflection and a model rocket combustor simulation demonstrate the eligibility of this technique to practical applications. Both test cases are simulated successfully for the first time with a hybrid finite-volume (FV)/Lagrangian particle solver (PS).
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.
Modeling metal stocks and flows: a review of dynamic material flow analysis methods.
Müller, Esther; Hilty, Lorenz M; Widmer, Rolf; Schluep, Mathias; Faulstich, Martin
2014-02-18
Dynamic material flow analysis (MFA) is a frequently used method to assess past, present, and future stocks and flows of metals in the anthroposphere. Over the past fifteen years, dynamic MFA has contributed to increased knowledge about the quantities, qualities, and locations of metal-containing goods. This article presents a literature review of the methodologies applied in 60 dynamic MFAs of metals. The review is based on a standardized model description format, the ODD (overview, design concepts, details) protocol. We focus on giving a comprehensive overview of modeling approaches and structure them according to essential aspects, such as their treatment of material dissipation, spatial dimension of flows, or data uncertainty. The reviewed literature features similar basic modeling principles but very diverse extrapolation methods. Basic principles include the calculation of outflows of the in-use stock based on inflow or stock data and a lifetime distribution function. For extrapolating stocks and flows, authors apply constant, linear, exponential, and logistic models or approaches based on socioeconomic variables, such as regression models or the intensity-of-use hypothesis. The consideration and treatment of further aspects, such as dissipation, spatial distribution, and data uncertainty, vary significantly and highly depends on the objectives of each study.
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.
Simulation of dry granular flows using discrete element methods
NASA Astrophysics Data System (ADS)
Martin, Hugo; Lefebvre, Aline; Maday, Yvon; Mangeney, Anne; Maury, Bertrand; Sainte-Marie, Jacques
2017-04-01
Granular flows are composed of interacting particles (for instance sand grains). While natural flow simulations at the field scale are generally based on continuum models, discrete element methods are very useful to get insight into the detailed contact interactions between the particles involved. We shall consider here both well known molecular dynamics (MD) and contact dynamics (CD) methods to simulate granular particle interaction. The difference between these methods is the linearisation of contact forces in MD. We are interested to compare these methods, and especially the effects of the linearisation in simulations. In the present work, we introduce a new rigid bodies model at the scale of the particles and its resolution by contact dynamics. The interesting aspect of our CD method is to treat the contacts in all the material system in one step without any iterative process required when the contacts are dealt with one after the other. All contacts are calculated here at the same time in just one iteration and the normal and tangential constraints are treated simultaneously. The present model follows from a convex optimization problem presented in [1] by B. Maury in which we add a frictional behaviour to the contact law between the particles. To analyse the behaviour of this model, we compare our results to analytical solutions when we can compute them and otherwise to simulations with molecular dynamics method. [1] A time-stepping scheme for inelastic collisions. Numerical handling of the nonoverlapping constraint, B. Maury, Numerische Mathematik, 17 january 2006.
Path planning in uncertain flow fields using ensemble method
NASA Astrophysics Data System (ADS)
Wang, Tong; Le Maître, Olivier P.; Hoteit, Ibrahim; Knio, Omar M.
2016-10-01
An ensemble-based approach is developed to conduct optimal path planning in unsteady ocean currents under uncertainty. We focus our attention on two-dimensional steady and unsteady uncertain flows, and adopt a sampling methodology that is well suited to operational forecasts, where an ensemble of deterministic predictions is used to model and quantify uncertainty. In an operational setting, much about dynamics, topography, and forcing of the ocean environment is uncertain. To address this uncertainty, the flow field is parametrized using a finite number of independent canonical random variables with known densities, and the ensemble is generated by sampling these variables. For each of the resulting realizations of the uncertain current field, we predict the path that minimizes the travel time by solving a boundary value problem (BVP), based on the Pontryagin maximum principle. A family of backward-in-time trajectories starting at the end position is used to generate suitable initial values for the BVP solver. This allows us to examine and analyze the performance of the sampling strategy and to develop insight into extensions dealing with general circulation ocean models. In particular, the ensemble method enables us to perform a statistical analysis of travel times and consequently develop a path planning approach that accounts for these statistics. The proposed methodology is tested for a number of scenarios. We first validate our algorithms by reproducing simple canonical solutions, and then demonstrate our approach in more complex flow fields, including idealized, steady and unsteady double-gyre flows.
An improved higher order panel method for linearized supersonic flow
NASA Technical Reports Server (NTRS)
Ehlers, F. E.; Epton, M. A.; Johnson, F. T.; Magnus, A. E.; Rubbert, P. E.
1978-01-01
An improved higher order panel method for linearized supersonic flow is described. Each panel, defined by four points on the surface, is divided into eight subpanels in such a way that all subpanel and panel edges are contiguous. By prescribing a quadratic distribution of the doublet on each subpanel, the doublet strength is made strictly continuous on the paneled surface. A linear source distribution is also used. Numerical results are smoother and in better agreement with experiment than the previous method with less strict continuity. A brief discussion of superinclined panels used to eliminate interior interference in nacelles is included.
High Order Accuracy Methods for Supersonic Reactive Flows
2008-06-25
bubble interactions [12], the supersonic cavity flows [11], and etc. The difficulty of implement - ing the spectral method to these complex fluid...enhance the convergence properties of the approximation via a filter function σ(η) [30] with the following properties σ(η)= σ(−η), σ(±1) = 0, σ(0)= 1, σ... implementation of the Hybrid method depends on the ability to obtain accurate information on the smoothness of a function . In this work, we employ the Multi
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.
An improved higher order panel method for linearized supersonic flow
NASA Technical Reports Server (NTRS)
Ehlers, F. E.; Epton, M. A.; Johnson, F. T.; Magnus, A. E.; Rubbert, P. E.
1978-01-01
An improved higher order panel method for linearized supersonic flow is described. Each panel, defined by four points on the surface, is divided into eight subpanels in such a way that all subpanel and panel edges are contiguous. By prescribing a quadratic distribution of the doublet on each subpanel, the doublet strength is made strictly continuous on the paneled surface. A linear source distribution is also used. Numerical results are smoother and in better agreement with experiment than the previous method with less strict continuity. A brief discussion of superinclined panels used to eliminate interior interference in nacelles is included.
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.
Heat transfer in internal turbulent flows using the PDF method
Mazumder, S.; Modest, M.F.
1996-12-31
One of the strengths of the velocity-composition joint probability density function (PDF) method lies in its ability to predict scalar fields for reactive turbulent flows. The application of PDF methods to internal flows necessitates appropriate description of near-wall effects, namely, molecular transport, production of turbulence by inhomogeneities, and dissipation of the scalar fluctuations by viscosity. A Lagrangian transport equation has been derived for transport of energy, whereby convection is treated exactly. The temperature fluctuations are modeled by a modified version of a deterministic model, which was originally developed for homogeneous turbulence. The thermal wall-functions were used to incorporate these modifications. The resultant modeled Lagrangian energy transport equation is solved simultaneously with the hydrodynamic equations, for the test case of a thermally developing two-dimensional channel flow (parallel plate geometry). The model has been tested for both constant temperature and constant heat flux boundary conditions. Results obtained have been compared to {kappa}-{epsilon} and algebraic Reynolds stress model (ARSM) finite-volume calculations. Apart from the differences due to turbulence models, it was observed that the finite-volume calculations suffered numerical diffusion, which was completely eliminated in the Lagrangian PDF approach.
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.
Higher order time integration methods for two-phase flow
NASA Astrophysics Data System (ADS)
Kees, Christopher E.; Miller, Cass T.
Time integration methods that adapt in both the order of approximation and time step have been shown to provide efficient solutions to Richards' equation. In this work, we extend the same method of lines approach to solve a set of two-phase flow formulations and address some mass conservation issues from the previous work. We analyze these formulations and the nonlinear systems that result from applying the integration methods, placing particular emphasis on their index, range of applicability, and mass conservation characteristics. We conduct numerical experiments to study the behavior of the numerical models for three test problems. We demonstrate that higher order integration in time is more efficient than standard low-order methods for a variety of practical grids and integration tolerances, that the adaptive scheme successfully varies the step size in response to changing conditions, and that mass balance can be maintained efficiently using variable-order integration and an appropriately chosen numerical model formulation.
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.
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)
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)
NASA Technical Reports Server (NTRS)
Kim, S.-W.; Chen, C.-P.
1988-01-01
A review on various experimental, analytical, and numerical methods for the flow-solid interaction of a nest of cylinders subjected to cross flow is presented in this paper. In order to assess the possibility of initiating a development of major numerical analysis method for flow-solid interaction of a nest of cylinders in cross flows, a review on various turbulence models, numerical methods such as the finite element method and the finite difference method, and the available numerical methods for flow-solid interactions have been included in this paper. A multiple-time-scale turbulence model for complex turbulent flows and a finite element method for high Reynolds number flows have been introduced herein for the same reason.
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.
An efficient pressure-correction method for incompressible multifluid flows
NASA Astrophysics Data System (ADS)
Dodd, M.; Ferrante, A.
2013-11-01
We present a new pressure-correction (PC) method for solving incompressible multifluid flows with large density ratios. The novelty of the method is that the variable coefficient Poisson equation that arises in solving the variable-density Navier-Stokes equations has been reduced to a constant coefficient equation, which can then be solved directly using a fast Poisson solver. The new method is coupled to our mass-conserving volume-of-fluid (VoF) method to capture the interface between the moving fluids. First, we verified the new PC/VoF solver using the capillary wave test-case up to density and viscosity ratios of 10,000. Then, we validated the new flow solver by simulating the motion of a falling water droplet in air by comparing the droplet terminal velocity with the experimental value (Beard, 1976) for 95 . 6 <= Re <= 473 , 0 . 06 <= We <= 0 . 61 , and 0 . 05 <= Bo <= 0 . 26 . We also verified the solver for a rising air bubble in water. The algorithm is shown to be second-order accurate, and stable for density and viscosity ratios up to 10,000. Also, we show that our fast Poisson solver is more than ten times faster than the Hypre multigrid solver up to a 10243 grid and 1024 cores. NSF CAREER #1054591.
Incompressible material point method for free surface flow
NASA Astrophysics Data System (ADS)
Zhang, Fan; Zhang, Xiong; Sze, Kam Yim; Lian, Yanping; Liu, Yan
2017-02-01
To overcome the shortcomings of the weakly compressible material point method (WCMPM) for modeling the free surface flow problems, an incompressible material point method (iMPM) is proposed based on operator splitting technique which splits the solution of momentum equation into two steps. An intermediate velocity field is first obtained by solving the momentum equations ignoring the pressure gradient term, and then the intermediate velocity field is corrected by the pressure term to obtain a divergence-free velocity field. A level set function which represents the signed distance to free surface is used to track the free surface and apply the pressure boundary conditions. Moreover, an hourglass damping is introduced to suppress the spurious velocity modes which are caused by the discretization of the cell center velocity divergence from the grid vertexes velocities when solving pressure Poisson equations. Numerical examples including dam break, oscillation of a cubic liquid drop and a droplet impact into deep pool show that the proposed incompressible material point method is much more accurate and efficient than the weakly compressible material point method in solving free surface flow problems.
Methods for blood flow measurements using ultrasound contrast agents
NASA Astrophysics Data System (ADS)
Fowlkes, J. Brian
2003-10-01
Blood flow measurements using ultrasound contrast agents are being investigated for myocardial perfusion and more recently in other organ systems. The methods are based largely on the relative increase in echogenicity due to the concentration of bubbles present in the ultrasound beam. In the simplest form, regional differences in blood volume can be inferred but the possibility exists to extract perfusion from the transit of contrast agent through tissue. Perfusion measurements rely on determining the flux of blood through a tissue volume and as such require knowledge of the fractional blood volume (FBV), i.e., ml blood/g tissue and the rate of exchange, commonly measured as the mean transit time (MTT). This presentation will discuss methods of determining each of these values and their combination to estimate tissue perfusion. Underlying principles of indicator-dilution theory will be provided in the context of ultrasound contrast agents. Current methods for determining MTT will include imaging of the intravenous bolus, in-plane contrast disruption with interval and real-time contrast recovery imaging, and control of contrast agent flow using arterial disruption (contrast interruption). The advantages and limitations of the methods will be examined along with current applications. [Work supported in part by NIH.
A Level Set Method for vaporizing two-phase flows
NASA Astrophysics Data System (ADS)
Tanguy, Sébastien; Ménard, Thibaut; Berlemont, Alain
2007-02-01
Development and applications of numerical methods devoted to reactive interface simulations are presented. Emphasis is put on vaporization, where numerical difficulties arise in imposing accurate jump conditions for heat and mass transfers. We use both the Level Set Method and the Ghost Fluid Method to capture the interface motion accurately and to handle suitable jump conditions. A local vaporization mass flow rate per unit of surface area is defined and Stefan flow is involved in the process. Specific care has been devoted to the extension of discontinuous variables across the interface to populate ghost cells, in order to avoid parasitic currents and numerical diffusion across the interface. A projection method is set up to impose both the velocity field continuity and a divergence-free condition for the extended velocity field across the interface. The d2 law is verified in the numerical simulations of the vaporization of an isolated static drop. Results are then presented for a water droplet moving in air. Vapor mass fraction and temperature fields inside and outside the droplet are presented.
A direct simulation method for flows with suspended paramagnetic particles
Kang, Tae Gon; Hulsen, Martien A. Toonder, Jaap M.J. den; Anderson, Patrick D.; Meijer, Han E.H.
2008-04-20
A direct numerical simulation method based on the Maxwell stress tensor and a fictitious domain method has been developed to solve flows with suspended paramagnetic particles. The numerical scheme enables us to take into account both hydrodynamic and magnetic interactions between particles in a fully coupled manner. Particles are assumed to be non-Brownian with negligible inertia. Rigid body motions of particles in 2D are described by a rigid-ring description implemented by Lagrange multipliers. The magnetic force, acting on the particles due to magnetic fields, is represented by the divergence of the Maxwell stress tensor, which acts as a body force added to the momentum balance equation. Focusing on two-dimensional problems, we solve a single-particle problem for verification. With the magnetic force working on the particle, the proper number of collocation points is found to be two points per element. The convergence with mesh refinement is verified by comparing results from regular mesh problems with those from a boundary-fitted mesh problem as references. We apply the developed method to two application problems: two-particle interaction in a uniform magnetic field and the motion of a magnetic chain in a rotating field, demonstrating the capability of the method to tackle general problems. In the motion of a magnetic chain, especially, the deformation pattern at break-up is similar to the experimentally observed one. The present formulation can be extended to three-dimensional and viscoelastic flow problems.
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.
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.
An optical flow-based method for velocity field of fluid flow estimation
NASA Astrophysics Data System (ADS)
Głomb, Grzegorz; Świrniak, Grzegorz; Mroczka, Janusz
2017-06-01
The aim of this paper is to present a method for estimating flow-velocity vector fields using the Lucas-Kanade algorithm. The optical flow measurements are based on the Particle Image Velocimetry (PIV) technique, which is commonly used in fluid mechanics laboratories in both research institutes and industry. Common approaches for an optical characterization of velocity fields base on computation of partial derivatives of the image intensity using finite differences. Nevertheless, the accuracy of velocity field computations is low due to the fact that an exact estimation of spatial derivatives is very difficult in presence of rapid intensity changes in the PIV images, caused by particles having small diameters. The method discussed in this paper solves this problem by interpolating the PIV images using Gaussian radial basis functions. This provides a significant improvement in the accuracy of the velocity estimation but, more importantly, allows for the evaluation of the derivatives in intermediate points between pixels. Numerical analysis proves that the method is able to estimate even a separate vector for each particle with a 5× 5 px2 window, whereas a classical correlation-based method needs at least 4 particle images. With the use of a specialized multi-step hybrid approach to data analysis the method improves the estimation of the particle displacement far above 1 px.
Introductory small cash incentives to promote child spacing in India.
Stevens, J R; Stevens, C M
1992-01-01
The Ammanpettai Family Welfare Program began in 1985 as a pilot program to determine whether offering small monthly cash incentives for a limited period would be a cost-effective way to increase the use of modern temporary methods of contraception among rural Indian women who do not want to become pregnant but are not ready to adopt sterilization. The program has demonstrated that a modest cash incentive for 3-5 months attracts very large numbers of women to a clinic where they learn about and are provided with the pill, condoms, or the IUD. In catchment areas where official government reports showed temporary-methods prevalence rates of 3-5 percent at best, the Ammanpettai incentive program has attracted up to 70 percent of eligible women to join the program and try the method of their choice. By requiring that participants bring their youngest child to the clinic, the program provides for mother and child health surveillance, including immunizations. The great majority of rural women who join the program work as field laborers, have little or no schooling, and have little knowledge of or experience with modern contraceptive methods. Continuation rates are 25-50 percent at one year if follow-up is maintained by village resident women distributors. The program has been extended to several rural primary health centers in Thanjavur District, to 14 government health posts in the city of Madras, and to a semiurban area and several rural areas in Bihar. The cost-effectiveness of this program compares favorably with that of the current government family welfare program.
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.
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.
Flow resistance and its prediction methods in compound channels
NASA Astrophysics Data System (ADS)
Yang, Kejun; Cao, Shuyou; Liu, Xingnian
2007-02-01
A series of experiments was carried out in a large symmetric compound channel composed of a rough main channel and rough floodplains to investigate the resistance characteristics of inbank and overbank flows. The effective Manning, Darcy-Weisbach, Chezy coefficients and the relative Nikuradse roughness height were analyzed. Many different representative methods for predicting the composite roughness were systematically summarized. Besides the measured data, a vast number of laboratory data and field data for compound channels were collected and used to check the validity of these methods for different subsection divisions including the vertical, horizontal, diagonal and bisectional divisions. The computation showed that these methods resulted in big errors in assessing the composite roughness in compound channels, and the reasons were analyzed in detail. The error magnitude is related to the subsection divisions.
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.
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). Copyright © 2015 Elsevier B.V. All rights reserved.
Vortex methods for two- and three-dimensional flow simulations
NASA Technical Reports Server (NTRS)
Leonard, A.
1980-01-01
The point vortex and vortex blob methods for two dimensional flows are presented. Several results are discussed concerning the numerical analysis of the latter scheme, e.g., the preservation of globally conserved quantities and the analysis of the spatial discretization error resulting from the convection of fixed blobs of vorticity. An application to the two dimensional mixing layer is briefly described. The contour dynamics method is also discussed. The simulation of three dimensional flows with vortex methods is discussed. A natural way to represent the vorticity is in the form of closed tubes of filaments of vorticity, although other schemes are examined. Applications to aircraft trailing vortices and to a turbulent spot in a laminar boundary layer are presented. Hybrid schemes that use an Eulerian mesh to solve the Poisson equation for the velocity field are discussed. The goal of these schemes is to avoid the high cost of the Biot-Savart integration if many vortex elements are used while enjoying most of the advantages of pure Lagrangian schemes.
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.
Polymeric drug nanoparticles prepared by an aerosol flow reactor method.
Eerikäinen, Hannele; Kauppinen, Esko I; Kansikas, Jarno
2004-01-01
Our purpose was to study the possibility of using a novel method, namely, aerosol flow reactor method, for the preparation of drug-containing nanoparticles with varying amounts of drug and polymer. The physical properties of the prepared nanoparticles were analyzed. The nanoparticle size distributions were measured using differential mobility analyzer. The structure of the prepared nanoparticles was assessed by x-ray diffraction, differential scanning calorimetry, and electron microscopy. Drug release from the nanoparticles was analyzed. The spherical particles produced showed a unimodal and lognormal size distribution, and the geometric number mean size of the nanoparticles could be varied between 90 and 200 nm. When the amount of drug in the polymeric matrix was small, the nanoparticles had a homogeneous, amorphous structure. Drug crystals were formed when the amount of drug was increased over the solubility limit of the drug into the polymer. The amounts of drug and polymer controlled the drug release from the nanoparticles. The aerosol flow reactor method was found to be able to produce homogeneous amorphous matrix-type nanoparticles that can directly be collected as dry powder.
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.
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
Simple numerical method for predicting steady compressible flows
NASA Technical Reports Server (NTRS)
Von Lavante, E.; Melson, N. Duane
1987-01-01
The present numerical method for the solution of the isenthalpic form of the governing equations for compressible viscous and inviscid flows has its basis in the concept of flux vector splitting in its implicit form, and has been tested in the cases of several difficult viscous and inviscid configurations. An acceleration of time-marching to steady state is accomplished by implementing a multigrid procedure which effectively increases the convergence rate. The steady state results obtained are largely of good quality, and required only short computational times.
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.
Method for flow cytometric detection of Listeria monocytogenes in milk.
Donnelly, C W; Baigent, G J
1986-01-01
This report describes a method for the detection of Listeria monocytogenes in raw milk by flow cytometric analysis of fluorescently labeled bacterial populations. The use of immunofluorescence in combination with measures of DNA content by propidium iodide labeling and size by light scattering enabled specific identification of L. monocytogenes from Streptococcus faecalis, Streptococcus agalactiae, Streptococcus uberis, Staphylococcus epidermidis, and Staphylococcus hyicus. Additional specific resolution of L. monocytogenes populations was achieved through selective enrichment of raw milk in Listeria enrichment broth. These procedures should permit the rapid screening of milk and other food samples for L. monocytogenes and eliminate many of the short-comings associated with conventional fluorescent-antibody procedures. PMID:3096202
Parabolized Navier-Stokes methods for hypersonic flows
NASA Technical Reports Server (NTRS)
Lawrence, Scott L.
1991-01-01
A representative sampling of the techniques used in the integration of the Parabolized Navier-Stokes (PNS) equations is presented. Special atention is given to recent algorithms developed specifically for application to high speed flows, characterized by the presence of strong embedded shock waves and real gas effects. It is shown that PNS solvers are being used in the analysis of sonic boom signatures. Methods for modeling physical effects are discussed, including an overview of commonly used turbulence models and a more detailed discussion of techniques for including equilibrium and finite rate real gas effects.
47 CFR 32.1120 - Cash and equivalents.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 47 Telecommunication 2 2010-10-01 2010-10-01 false Cash and equivalents. 32.1120 Section 32.1120 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES UNIFORM SYSTEM OF ACCOUNTS FOR TELECOMMUNICATIONS COMPANIES Instructions for Balance Sheet Accounts § 32.1120 Cash...
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)
Cash Management in the United States Marine Corps.
1984-12-01
is made by cash, payment date is that business day when the cash is tendered . Paragraph 7 governs interest payments. In general, whenever payment has...payment due period under the Act. However, steak dinners at restaurants for Reservists on weekend drill are not considered by the MCFC to be within the
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)
18 CFR 154.306 - Cash working capital.
Code of Federal Regulations, 2010 CFR
2010-04-01
... may not receive a cash working capital adjustment to its rate base unless the company or other... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Cash working capital..., DEPARTMENT OF ENERGY REGULATIONS UNDER NATURAL GAS ACT RATE SCHEDULES AND TARIFFS Material To Be Filed With...
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... equalize the agreed upon values of the Federal and non-Federal lands involved in an exchange, either with... cash equalization after making all reasonable efforts to equalize values by adding or excluding...
43 CFR 2201.6 - Value equalization; cash equalization waiver.
Code of Federal Regulations, 2014 CFR
2014-10-01
... 43 Public Lands: Interior 2 2014-10-01 2014-10-01 false Value equalization; cash equalization... equalize the agreed upon values of the Federal and non-Federal lands involved in an exchange, either with... cash equalization after making all reasonable efforts to equalize values by adding or excluding...
20 CFR 255.5 - Recovery by cash payment.
Code of Federal Regulations, 2010 CFR
2010-04-01
... 20 Employees' Benefits 1 2010-04-01 2010-04-01 false Recovery by cash payment. 255.5 Section 255.5 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE RAILROAD RETIREMENT ACT RECOVERY OF OVERPAYMENTS § 255.5 Recovery by cash payment. The Board shall have the right to require that an overpayment...
20 CFR 340.5 - Recovery by cash payment.
Code of Federal Regulations, 2010 CFR
2010-04-01
... 20 Employees' Benefits 1 2010-04-01 2010-04-01 false Recovery by cash payment. 340.5 Section 340.5 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE RAILROAD UNEMPLOYMENT INSURANCE ACT RECOVERY OF BENEFITS § 340.5 Recovery by cash payment. The Board shall have the right to require...
20 CFR 255.5 - Recovery by cash payment.
Code of Federal Regulations, 2011 CFR
2011-04-01
... 20 Employees' Benefits 1 2011-04-01 2011-04-01 false Recovery by cash payment. 255.5 Section 255.5 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE RAILROAD RETIREMENT ACT RECOVERY OF OVERPAYMENTS § 255.5 Recovery by cash payment. The Board shall have the right to require that an overpayment...
20 CFR 340.5 - Recovery by cash payment.
Code of Federal Regulations, 2011 CFR
2011-04-01
... 20 Employees' Benefits 1 2011-04-01 2011-04-01 false Recovery by cash payment. 340.5 Section 340.5 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE RAILROAD UNEMPLOYMENT INSURANCE ACT RECOVERY OF BENEFITS § 340.5 Recovery by cash payment. The Board shall have the right to require...
7 CFR 3015.83 - Federal cash transactions report.
Code of Federal Regulations, 2012 CFR
2012-01-01
... 7 Agriculture 15 2012-01-01 2012-01-01 false Federal cash transactions report. 3015.83 Section 3015.83 Agriculture Regulations of the Department of Agriculture (Continued) OFFICE OF THE CHIEF... Requirements § 3015.83 Federal cash transactions report. (a) Form. (1) For grants or cooperative agreements...
7 CFR 3015.83 - Federal cash transactions report.
Code of Federal Regulations, 2013 CFR
2013-01-01
... 7 Agriculture 15 2013-01-01 2013-01-01 false Federal cash transactions report. 3015.83 Section 3015.83 Agriculture Regulations of the Department of Agriculture (Continued) OFFICE OF THE CHIEF... Requirements § 3015.83 Federal cash transactions report. (a) Form. (1) For grants or cooperative agreements...
7 CFR 3015.83 - Federal cash transactions report.
Code of Federal Regulations, 2014 CFR
2014-01-01
... 7 Agriculture 15 2014-01-01 2014-01-01 false Federal cash transactions report. 3015.83 Section 3015.83 Agriculture Regulations of the Department of Agriculture (Continued) OFFICE OF THE CHIEF... Requirements § 3015.83 Federal cash transactions report. (a) Form. (1) For grants or cooperative agreements...
7 CFR 3015.83 - Federal cash transactions report.
Code of Federal Regulations, 2011 CFR
2011-01-01
... 7 Agriculture 15 2011-01-01 2011-01-01 false Federal cash transactions report. 3015.83 Section 3015.83 Agriculture Regulations of the Department of Agriculture (Continued) OFFICE OF THE CHIEF... Requirements § 3015.83 Federal cash transactions report. (a) Form. (1) For grants or cooperative agreements...
Code of Federal Regulations, 2010 CFR
2010-10-01
... 42 Public Health 4 2010-10-01 2010-10-01 false Use of cash. 441.454 Section 441.454 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL... applicable, using the cash option to choose to use the financial management entity for some or all of the...
38 CFR 8.11 - Cash value and policy loan.
Code of Federal Regulations, 2011 CFR
2011-07-01
... SERVICE LIFE INSURANCE Cash Value and Policy Loan § 8.11 Cash value and policy loan. (a) Provisions for... become effective at the completion of the first policy year on any plan of National Service Life... participating National Service Life Insurance, other than as provided in paragraph (e) of this section, shall be...
38 CFR 8.11 - Cash value and policy loan.
Code of Federal Regulations, 2014 CFR
2014-07-01
... SERVICE LIFE INSURANCE Cash Value and Policy Loan § 8.11 Cash value and policy loan. (a) Provisions for... become effective at the completion of the first policy year on any plan of National Service Life... participating National Service Life Insurance, other than as provided in paragraph (e) of this section, shall be...
38 CFR 8.11 - Cash value and policy loan.
Code of Federal Regulations, 2013 CFR
2013-07-01
... SERVICE LIFE INSURANCE Cash Value and Policy Loan § 8.11 Cash value and policy loan. (a) Provisions for... become effective at the completion of the first policy year on any plan of National Service Life... participating National Service Life Insurance, other than as provided in paragraph (e) of this section, shall be...
38 CFR 8.11 - Cash value and policy loan.
Code of Federal Regulations, 2010 CFR
2010-07-01
... SERVICE LIFE INSURANCE Cash Value and Policy Loan § 8.11 Cash value and policy loan. (a) Provisions for... become effective at the completion of the first policy year on any plan of National Service Life... participating National Service Life Insurance, other than as provided in paragraph (e) of this section, shall be...
18 CFR 367.1310 - Account 131, Cash.
Code of Federal Regulations, 2013 CFR
2013-04-01
... THE PUBLIC UTILITY HOLDING COMPANY ACT OF 2005, FEDERAL POWER ACT AND NATURAL GAS ACT Balance Sheet Chart of Accounts Current and Accrued Assets § 367.1310 Account 131, Cash. This account must include the amount of current cash funds except working funds....
18 CFR 367.1310 - Account 131, Cash.
Code of Federal Regulations, 2014 CFR
2014-04-01
... THE PUBLIC UTILITY HOLDING COMPANY ACT OF 2005, FEDERAL POWER ACT AND NATURAL GAS ACT Balance Sheet Chart of Accounts Current and Accrued Assets § 367.1310 Account 131, Cash. This account must include the amount of current cash funds except working funds....
18 CFR 367.1310 - Account 131, Cash.
Code of Federal Regulations, 2011 CFR
2011-04-01
... THE PUBLIC UTILITY HOLDING COMPANY ACT OF 2005, FEDERAL POWER ACT AND NATURAL GAS ACT Balance Sheet Chart of Accounts Current and Accrued Assets § 367.1310 Account 131, Cash. This account must include the amount of current cash funds except working funds....
18 CFR 367.1310 - Account 131, Cash.
Code of Federal Regulations, 2012 CFR
2012-04-01
... THE PUBLIC UTILITY HOLDING COMPANY ACT OF 2005, FEDERAL POWER ACT AND NATURAL GAS ACT Balance Sheet Chart of Accounts Current and Accrued Assets § 367.1310 Account 131, Cash. This account must include the amount of current cash funds except working funds....
18 CFR 367.1310 - Account 131, Cash.
Code of Federal Regulations, 2010 CFR
2010-04-01
... THE PUBLIC UTILITY HOLDING COMPANY ACT OF 2005, FEDERAL POWER ACT AND NATURAL GAS ACT Balance Sheet Chart of Accounts Current and Accrued Assets § 367.1310 Account 131, Cash. This account must include the amount of current cash funds except working funds....
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.
7 CFR 1942.128 - Borrower accounting methods, management reports and audits.
Code of Federal Regulations, 2010 CFR
2010-01-01
... under Public Law 103-354 1942-53, “Cash Flow Report,” instead of page one of schedule one and schedule..., and Equity.” When used for budgeting, the cash statement should be projected for the upcoming fiscal year. When used for quarterly or annual reports, the cash flow report should include current...
Effects of Cash and Counseling on Personal Care and Well-Being
Carlson, Barbara Lepidus; Foster, Leslie; Dale, Stacy B; Brown, Randall
2007-01-01
Objective To examine how a new model of consumer-directed care changes the way that consumers with disabilities meet their personal care needs and, in turn, affects their well-being. Study Setting Eligible Medicaid beneficiaries in Arkansas, Florida, and New Jersey volunteered to participate in the demonstration and were randomly assigned to receive an allowance and direct their own Medicaid supportive services as Cash and Counseling consumers (the treatment group) or to rely on Medicaid services as usual (the control group). The demonstration included elderly and nonelderly adults in all three states and children in Florida. Data Sources Telephone interviews administered 9 months after random assignment. Methods Outcomes for the treatment and control group were compared, using regression analysis to control for consumers' baseline characteristics. Principal Findings Treatment group members were more likely to receive paid care, had greater satisfaction with their care, and had fewer unmet needs than control group members in nearly every state and age group. However, among the elderly in Florida, Cash and Counseling had little effect on these outcomes because so few treatment group members actually received the allowance. Within each state and age group, consumers were not more susceptible to adverse health outcomes or injuries under Cash and Counseling. Conclusions Cash and Counseling substantially improves the lives of Medicaid beneficiaries of all ages if consumers actually receive the allowance that the program offers. PMID:17244293
Fast multipole method applied to Lagrangian simulations of vortical flows
NASA Astrophysics Data System (ADS)
Ricciardi, Túlio R.; Wolf, William R.; Bimbato, Alex M.
2017-10-01
Lagrangian simulations of unsteady vortical flows are accelerated by the multi-level fast multipole method, FMM. The combination of the FMM algorithm with a discrete vortex method, DVM, is discussed for free domain and periodic problems with focus on implementation details to reduce numerical dissipation and avoid spurious solutions in unsteady inviscid flows. An assessment of the FMM-DVM accuracy is presented through a comparison with the direct calculation of the Biot-Savart law for the simulation of the temporal evolution of an aircraft wake in the Trefftz plane. The role of several parameters such as time step restriction, truncation of the FMM series expansion, number of particles in the wake discretization and machine precision is investigated and we show how to avoid spurious instabilities. The FMM-DVM is also applied to compute the evolution of a temporal shear layer with periodic boundary conditions. A novel approach is proposed to achieve accurate solutions in the periodic FMM. This approach avoids a spurious precession of the periodic shear layer and solutions are shown to converge to the direct Biot-Savart calculation using a cotangent function.
Multi-scale simulation method for electroosmotic flows
NASA Astrophysics Data System (ADS)
Guo, Lin; Chen, Shiyi; Robbins, Mark O.
2016-10-01
Electroosmotic transport in micro-and nano- channels has important applications in biological and engineering systems but is difficult to model because nanoscale structure near surfaces impacts flow throughout the channel. We develop an efficient multi-scale simulation method that treats near-wall and bulk subdomains with different physical descriptions and couples them through a finite overlap region. Molecular dynamics is used in the near-wall subdomain where the ion density is inconsistent with continuum models and the discrete structure of solvent molecules is important. In the bulk region the solvent is treated as a continuum fluid described by the incompressible Navier-Stokes equations with thermal fluctuations. A discrete description of ions is retained because of the low density of ions and the long range of electrostatic interactions. A stochastic Euler-Lagrangian method is used to simulate the dynamics of these ions in the implicit continuum solvent. The overlap region allows free exchange of solvent and ions between the two subdomains. The hybrid approach is validated against full molecular dynamics simulations for different geometries and types of flows.
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.
Traffic flow equations coming from the Grad's method.
NASA Astrophysics Data System (ADS)
Velasco, Rosa M.; Méndez, Alma R.
2006-11-01
The usual Grad's method in kinetic theory of gases is developed to construct a new model in traffic flow problems. This is applied to the kinetic equation called as the Paveri-Fontana equation which tells us how the distribution function evolves in time [1]. We assume a special model for the desired velocity of drivers [2] and the Grad's method provides us with a closure relation in the macroscopic equations. The simulation results for this model allow us to find the behavior of density, mean velocity and the velocity variance in the system. All the results are consistent with the validity region of the kinetic equation and with the qualitative behavior proper to traffic models. We show some comparisons with other models in the literature [3]. [1] S.L Paveri-Fontana; Transp. Res. 9 (1975), 225. [2] R.M. Velasco, W. Marques Jr.; Phys. Rev. E72 (2005), 046102. [3] D. Helbing; Phys. Rev. E51 (1995), 3164.
Preconditioning Newton-Krylor Methods for Variably Saturated Flow
Woodward, C.; Jones, J
2000-01-07
In this paper, we compare the effectiveness of three preconditioning strategies in simulations of variably saturated flow. Using Richards' equation as our model, we solve the nonlinear system using a Newton-Krylov method. Since Krylov solvers can stagnate, resulting in slow convergence, we investigate different strategies of preconditioning the Jacobian system. Our work uses a multigrid method to solve the preconditioning systems, with three different approximations to the Jacobian matrix. One approximation lags the nonlinearities, the second results from discarding selected off-diagonal contributions, and the third matrix considered is the full Jacobian. Results indicate that although the Jacobian is more accurate, its usage as a preconditioning matrix should be limited, as it requires much more storage than the simpler approximations. Also, simply lagging the nonlinearities gives a preconditioning matrix that is almost as effective as the full Jacobian but much easier to compute.
Finite area method for nonlinear supersonic conical flows
NASA Technical Reports Server (NTRS)
Sritharan, S. S.; Seebass, A. R.
1983-01-01
A fully conservative numerical method for the computation of steady inviscid supersonic flow about general conical bodies at incidence is described. The procedure utilizes the potential approximation and implements a body conforming mesh generator. The conical potential is assumed to have its best linear variation inside each mesh cell; a secondary interlocking cell system is used to establish the flux balance required to conserve mass. In the supersonic regions the scheme is symmetrized by adding artificial viscosity in conservation form. The algorithm is nearly an order of a magnitude faster than present Euler methods and predicts known results accurately and qualitative features such as nodal point lift off correctly. Results are compared with those of other investigators.
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.
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 COMMISSION, DEPARTMENT OF THE INTERIOR HUMAN SERVICES MINIMUM INTERNAL CONTROL STANDARDS FOR CLASS II GAMING... individual accountability. All variances must be documented and investigated. (4) The gaming operation...
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 COMMISSION, DEPARTMENT OF THE INTERIOR HUMAN SERVICES MINIMUM INTERNAL CONTROL STANDARDS FOR CLASS II GAMING... individual accountability. All variances must be documented and investigated. (4) The gaming operation...
Approximate hard-sphere method for densely packed granular flows
NASA Astrophysics Data System (ADS)
Guttenberg, Nicholas
2011-05-01
The simulation of granular media is usually done either with event-driven codes that treat collisions as instantaneous but have difficulty with very dense packings, or with molecular dynamics (MD) methods that approximate rigid grains using a stiff viscoelastic spring. There is a little-known method that combines several collision events into a single timestep to retain the instantaneous collisions of event-driven dynamics, but also be able to handle dense packings. However, it is poorly characterized as to its regime of validity and failure modes. We present a modification of this method to reduce the introduction of overlap error, and test it using the problem of two-dimensional (2D) granular Couette flow, a densely packed system that has been well characterized by previous work. We find that this method can successfully replicate the results of previous work up to the point of jamming, and that it can do so a factor of 10 faster than comparable MD methods.
Approximate hard-sphere method for densely packed granular flows.
Guttenberg, Nicholas
2011-05-01
The simulation of granular media is usually done either with event-driven codes that treat collisions as instantaneous but have difficulty with very dense packings, or with molecular dynamics (MD) methods that approximate rigid grains using a stiff viscoelastic spring. There is a little-known method that combines several collision events into a single timestep to retain the instantaneous collisions of event-driven dynamics, but also be able to handle dense packings. However, it is poorly characterized as to its regime of validity and failure modes. We present a modification of this method to reduce the introduction of overlap error, and test it using the problem of two-dimensional (2D) granular Couette flow, a densely packed system that has been well characterized by previous work. We find that this method can successfully replicate the results of previous work up to the point of jamming, and that it can do so a factor of 10 faster than comparable MD methods.
Discontinuous Galerkin method for multicomponent chemically reacting flows and combustion
NASA Astrophysics Data System (ADS)
Lv, Yu; Ihme, Matthias
2014-08-01
This paper presents the development of a discontinuous Galerkin (DG) method for application to chemically reacting flows in subsonic and supersonic regimes under the consideration of variable thermo-viscous-diffusive transport properties, detailed and stiff reaction chemistry, and shock capturing. A hybrid-flux formulation is developed for treatment of the convective fluxes, combining a conservative Riemann-solver and an extended double-flux scheme. A computationally efficient splitting scheme is proposed, in which advection and diffusion operators are solved in the weak form, and the chemically stiff substep is advanced in the strong form using a time-implicit scheme. The discretization of the viscous-diffusive transport terms follows the second form of Bassi and Rebay, and the WENO-based limiter due to Zhong and Shu is extended to multicomponent systems. Boundary conditions are developed for subsonic and supersonic flow conditions, and the algorithm is coupled to thermochemical libraries to account for detailed reaction chemistry and complex transport. The resulting DG method is applied to a series of test cases of increasing physico-chemical complexity. Beginning with one- and two-dimensional multispecies advection and shock-fluid interaction problems, computational efficiency, convergence, and conservation properties are demonstrated. This study is followed by considering a series of detonation and supersonic combustion problems to investigate the convergence-rate and the shock-capturing capability in the presence of one- and multistep reaction chemistry. The DG algorithm is then applied to diffusion-controlled deflagration problems. By examining convergence properties for polynomial order and spatial resolution, and comparing these with second-order finite-volume solutions, it is shown that optimal convergence is achieved and that polynomial refinement provides advantages in better resolving the localized flame structure and complex flow-field features
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
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.
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.
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.
Acosta, Sebastian; Puelz, Charles; Riviére, 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.
Numerical Method of Characteristics for One–Dimensional Blood Flow
Puelz, Charles; Riviére, Béatrice; Penny, Daniel J.; Rusin, Craig G.
2015-01-01
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. PMID:25931614