Holomorphic Embedded Load Flow for Autonomous Spacecraft Power Systems, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — The proposed innovation advances the ability to apply the Holomorphic Embedding Load Flow Technology (HELM™) method to provide deterministic load flow modeling for...

The flow field investigations of no load conditions in axial flow fixed-blade turbine

Science.gov (United States)

Yang, J.; Gao, L.; Wang, Z. W.; Zhou, X. Z.; Xu, H. X.

2014-03-01

During the start-up process, the strong instabilities happened at no load operation in a low head axial flow fixed-blade turbine, with strong pressure pulsation and vibration. The rated speed can not reach until guide vane opening to some extent, and stable operation could not be maintained under the rated speed at some head, which had a negative impact on the grid-connected operation of the unit. In order to find the reason of this phenomenon, the unsteady flow field of the whole flow passage at no load conditions was carried out to analyze the detailed fluid field characteristics including the pressure pulsation and force imposed on the runner under three typical heads. The main hydraulic cause of no load conditions instability was described. It is recommended that the power station should try to reduce the no-load running time and go into the high load operation as soon as possible when connected to grid at the rated head. Following the recommendations, the plant operation practice proved the unstable degree of the unit was reduced greatly during start up and connect to the power grid.

Blade design loads on the flow exciting force in centrifugal pump

International Nuclear Information System (INIS)

Xu, Y; Yang, A L; Langand, D P; Dai, R

2012-01-01

The three-dimensional viscous flow field of two centrifugal pumps, which have the same volute, design head, design flow rate and rotational speed but the blade design load, are analyzed based on large eddy simulation. The comparisons are implemented including the hydraulic efficiencies, flow field characteristics, pressure pulsations and unsteady forces applied on the impellers to investigate the effect of the design blade load on hydraulic performance and flow exciting force. The numerical results show that the efficiency of the pump, the impeller blade of which has larger design load, is improved by 1.1%∼2.9% compared to the centrifugal pump with lower blade design load. The pressure fluctuation of the pump with high design load is more remarkable. Its maximum amplitude of coefficient of static pressure is higher by 43% than the latter. At the same time the amplitude of unsteady radial force is increased by 11.6% in the time domain. The results also imply that the blade design load is an important factor on the excitation force in centrifugal pumps.

Topology optimization considering design-dependent Stokes flow loads

NARCIS (Netherlands)

Picelli, R.; Vicente, W.M.; Pavanello, R.; van Keulen, A.; Li, Qing; Steven, Grant P.; Zhang, Zhongpu

2015-01-01

This article presents an evolutionary topology optimization method for mean compliance minimization of structures under design-dependent viscous fluid flow loads. The structural domain is governed by the elasticity equation and the fluid by the incompressible Stokes flow equations. When the

AC-DC integrated load flow calculation for variable speed offshore wind farms

DEFF Research Database (Denmark)

Zhao, Menghua; Chen, Zhe; Blaabjerg, Frede

2005-01-01

This paper proposes a sequential AC-DC integrated load flow algorithm for variable speed offshore wind farms. In this algorithm, the variable frequency and the control strategy of variable speed wind turbine systems are considered. In addition, the losses of wind turbine systems and the losses...... of converters are also integrated into the load flow algorithm. As a general algorithm, it can be applied to different types of wind farm configurations, and the load flow is related to the wind speed....

Thermally determining flow and/or heat load distribution in parallel paths

Science.gov (United States)

Chainer, Timothy J.; Iyengar, Madhusudan K.; Parida, Pritish R.

2016-12-13

A method including obtaining calibration data for at least one sub-component in a heat transfer assembly, wherein the calibration data comprises at least one indication of coolant flow rate through the sub-component for a given surface temperature delta of the sub-component and a given heat load into said sub-component, determining a measured heat load into the sub-component, determining a measured surface temperature delta of the sub-component, and determining a coolant flow distribution in a first flow path comprising the sub-component from the calibration data according to the measured heat load and the measured surface temperature delta of the sub-component.

Suppression of secondary flows in a double suction centrifugal pump with different loading distributions

International Nuclear Information System (INIS)

Leng, H F; Wang, F J; Zhang, Z C; Yao, Z F; Zhou, P J

2013-01-01

Secondary flow is one of the main reasons for low efficiency in double suction centrifugal pump. In a 3-D inverse design method, the pump blade could be designed by a specified loading distribution to control the flow field in pump. In order to study the influence of loading distribution on secondary flow of a double suction centrifugal pump, the external characteristics and the internal flow field of the pump with three kinds of loading distributions are analysed by using CFD approach. According to the simulation results, it is found that the form of fore-loading distribution at shroud and aft-loading distribution at hub could improve the optimal efficiency and broaden the high efficiency area of the pump. Furthermore, the secondary flow in impeller exit region and volute could be significantly suppressed if the slope of loading distribution curve of shroud is set to be −0.7

A network flow model for load balancing in circuit-switched multicomputers

Science.gov (United States)

Bokhari, Shahid H.

1990-01-01

In multicomputers that utilize circuit switching or wormhole routing, communication overhead depends largely on link contention - the variation due to distance between nodes is negligible. This has a major impact on the load balancing problem. In this case, there are some nodes with excess load (sources) and others with deficit load (sinks) and it is required to find a matching of sources to sinks that avoids contention. The problem is made complex by the hardwired routing on currently available machines: the user can control only which nodes communicate but not how the messages are routed. Network flow models of message flow in the mesh and the hypercube were developed to solve this problem. The crucial property of these models is the correspondence between minimum cost flows and correctly routed messages. To solve a given load balancing problem, a minimum cost flow algorithm is applied to the network. This permits one to determine efficiently a maximum contention free matching of sources to sinks which, in turn, tells one how much of the given imbalance can be eliminated without contention.

Load Flow and Short Circuit Analysis of the Class III Power System of HANARO

Energy Technology Data Exchange (ETDEWEB)

Kim, H. K.; Jung, H. S

2005-12-15

The planning, design, and operation of electric power system require engineering studies to assist in the evaluation of the system performance, reliability, safety and economics. The Class III power of HANARO supplies power for not only HANARO but also RIPF and IMEF. The starting current of most ac motors is five to ten times normal full load current. The loads of the Class III power are connected in consecutive orders at an interval for 10 seconds to avoid excessive voltage drop. This technical report deals with the load flow study and motor starting study for the Class III power of HANARO using ETAP(Electrical Transient Analyzer Program) to verify the capacity of the diesel generator. Short-circuit studies are done to determine the magnitude of the prospective currents flowing throughout the power system at various time intervals after a fault occurs. Short-circuit studies can be performed at the planning stage in order to help finalize the system layout, determine voltage levels, and size cables, transformers, and conductors. From this study, we verify the short circuit current capacity of air circuit breaker(ACB) and automatic transfer switch(ATS) of the Class III power.

System incremental cost calculations using the participation factor load-flow formulation

International Nuclear Information System (INIS)

Meisel, J.

1993-01-01

The load-flow problem is reformulated such that the use of a slack-bus generator is included only as a special case. This reformulation, known as the participation factor load-flow, includes a total mismatch variable and a defined participation vector, which, in general, distributes this mismatch to all system buses. The slack-bus constraint can still be obtained by defining a particular participation vector. In using the participation factor load-flow in the transpose Jacobian approach to the economic optimal dispatch problem, the paper shows that the value of the system-λ can be controlled such that this value represents the minimal incremental change in generation costs per unit change in system total demand with this demand distributed according to the specified participation vector. Methods using the conventional B-coefficient loss formulas or slack-bus load-flows give system-λ values whereby the unit change in demand must be placed on a fictitious single load-bus or on the slack-bus, respectively. Having a system-λ value which more accurately represents a proposed energy interchange between interconnected systems is very important in developing valid costs for each system. An extensive 28-bus, 8-generator system is included to illustrate these results

Application of the load flow and random flow models for the analysis of power transmission networks

International Nuclear Information System (INIS)

Zio, Enrico; Piccinelli, Roberta; Delfanti, Maurizio; Olivieri, Valeria; Pozzi, Mauro

2012-01-01

In this paper, the classical load flow model and the random flow model are considered for analyzing the performance of power transmission networks. The analysis concerns both the system performance and the importance of the different system elements; this latter is computed by power flow and random walk betweenness centrality measures. A network system from the literature is analyzed, representing a simple electrical power transmission network. The results obtained highlight the differences between the LF “global approach” to flow dispatch and the RF local approach of randomized node-to-node load transfer. Furthermore, computationally the LF model is less consuming than the RF model but problems of convergence may arise in the LF calculation.

Wide Area Protection Scheme Preventing Cascading Events Caused by Load Flow Transferring

DEFF Research Database (Denmark)

Liu, Zhou; Chen, Zhe; Sun, Haishun

2013-01-01

Load flow transferring after an initial contingency is regarded as one of the main reasons of causing unexpected cascading trips. A multi agent system (MAS) based wide area protection strategy is proposed in this paper to predict the load flow transferring from the point of view of impedance relays...

On load flow control in electric power systems

Energy Technology Data Exchange (ETDEWEB)

Herbig, Arnim

2000-01-01

This dissertation deals with the control of active power flow, or load flow in electric power systems. During the last few years, interest in the possibilities to control the active power flows in transmission systems has increased significantly. There is a number of reasons for this, coming both from the application side - that is, from power system operations - and from the technological side. where advances in power electronics and related technologies have made new system components available. Load flow control is by nature a multi-input multi-output problem, since any change of load flow in one line will be complemented by changes in other lines. Strong cross-coupling between controllable components is to be expected, and the possibility of adverse interactions between these components cannot be rejected straightaway. Interactions with dynamic phenomena in the power system are also a source of concern. Three controllable components are investigated in this thesis, namely the controlled series capacitor (CSC), the phase angle regulator (PAR), and the unified power flow controller (UPFC). Properties and characteristics of these devices axe investigated and discussed. A simple control strategy is proposed. This strategy is then analyzed extensively. Mathematical methods and physical knowledge about the pertinent phenomena are combined, and it is shown that this control strategy can be used for a fairly general class of devices. Computer simulations of the controlled system provide insight into the system behavior in a system of reasonable size. The robustness and stability of the control system are discussed as are its limits. Further, the behavior of the control strategy in a system where the modeling allows for dynamic phenomena are investigated with computer simulations. It is discussed under which circumstances the control action has beneficial or detrimental effect on the system dynamics. Finally, a graphical approach for analyzing the effect of controllers

River water quality management considering agricultural return flows: application of a nonlinear two-stage stochastic fuzzy programming.

Science.gov (United States)

Tavakoli, Ali; Nikoo, Mohammad Reza; Kerachian, Reza; Soltani, Maryam

2015-04-01

In this paper, a new fuzzy methodology is developed to optimize water and waste load allocation (WWLA) in rivers under uncertainty. An interactive two-stage stochastic fuzzy programming (ITSFP) method is utilized to handle parameter uncertainties, which are expressed as fuzzy boundary intervals. An iterative linear programming (ILP) is also used for solving the nonlinear optimization model. To accurately consider the impacts of the water and waste load allocation strategies on the river water quality, a calibrated QUAL2Kw model is linked with the WWLA optimization model. The soil, water, atmosphere, and plant (SWAP) simulation model is utilized to determine the quantity and quality of each agricultural return flow. To control pollution loads of agricultural networks, it is assumed that a part of each agricultural return flow can be diverted to an evaporation pond and also another part of it can be stored in a detention pond. In detention ponds, contaminated water is exposed to solar radiation for disinfecting pathogens. Results of applying the proposed methodology to the Dez River system in the southwestern region of Iran illustrate its effectiveness and applicability for water and waste load allocation in rivers. In the planning phase, this methodology can be used for estimating the capacities of return flow diversion system and evaporation and detention ponds.

Commercial equipment loads: End-Use Load and Consumer Assessment Program (ELCAP)

Energy Technology Data Exchange (ETDEWEB)

Pratt, R.G.; Williamson, M.A.; Richman, E.E.; Miller, N.E.

1990-07-01

The Office of Energy Resources of the Bonneville Power Administration is generally responsible for the agency's power and conservation resource planning. As associated responsibility which supports a variety of office functions is the analysis of historical trends in and determinants of energy consumption. The Office of Energy Resources' End-Use Research Section operates a comprehensive data collection program to provide pertinent information to support demand-side planning, load forecasting, and demand-side program development and delivery. Part of this on-going program is known as the End-Use Load and Consumer Assessment Program (ELCAP), an effort designed to collect electricity usage data through direct monitoring of end-use loads in buildings. This program is conducted for Bonneville by the Pacific Northwest Laboratory. This report provides detailed information on electricity consumption of miscellaneous equipment from the commercial portion of ELCAP. Miscellaneous equipment includes all commercial end-uses except heating, ventilating, air conditioning, and central lighting systems. Some examples of end-uses covered in this report are office equipment, computers, task lighting, refrigeration, and food preparation. Electricity consumption estimates, in kilowatt-hours per square food per year, are provided for each end-use by building type. The following types of buildings are covered: office, retail, restaurant, grocery, warehouse, school, university, and hotel/motel. 6 refs., 35 figs., 12 tabs.

Three phase load flow; Fluxo de carga trifasico

Energy Technology Data Exchange (ETDEWEB)

Zago, Maria Goretti

1992-12-01

The phase model which is used in the analysis and planning of electric power system is based on the hypothesis that both the transmission system and load are equilibrated. Such a system, which presents the advantage of being simple,presents satisfactory results in several cases, however, for certain applications this system is inadequate. this work presents an alternative method based on three-phase load flow which an be applied to electric power distribution networks 19 refs., 25 figs., 24 tabs.

Node Load Balance Multi-flow Opportunistic Routing in Wireless Mesh Networks

Directory of Open Access Journals (Sweden)

Wang Tao

2014-04-01

Full Text Available Opportunistic routing (OR has been proposed to improve the performance of wireless networks by exploiting the multi-user diversity and broadcast nature of the wireless medium. It involves multiple candidate forwarders to relay packets every hop. The existing OR doesn’t take account of the traffic load and load balance, therefore some nodes may be overloaded while the others may not, leading to network performance decline. In this paper, we focus on opportunities routing selection with node load balance which is described as a convex optimization problem. To solve the problem, by combining primal-dual and sub-gradient methods, a fully distributed Node load balance Multi-flow Opportunistic Routing algorithm (NMOR is proposed. With node load balance constraint, NMOR allocates the flow rate iteratively and the rate allocation decides the candidate forwarder selection of opportunities routing. The simulation results show that NMOR algorithm improves 100 %, 62 % of the aggregative throughput than ETX and EAX, respectively.

SEASONAL CHANGES IN PHOSPHORUS LOAD FLOWING OUT OF SMALL AGRICULTURAL CATCHMENTS

OpenAIRE

Krzysztof Pulikowski; Katarzyna Pawęska; Aleksandra Bawiec

2014-01-01

In this article distribution of monthly phosphorus loads flowing out of two agricultural catchments which are located in different physiographic conditions of Lower Silesia was analysed. Loads of phosphorus runoff from the catchment located in the piedmont part of Lower Silesia in each month rarely exceed 0.10 kg P ∙ ha-1. The size of annual load is determined by loads obtained in two months of early spring. Much lower loads obtained for lowland catchment, located near Wroclaw. Values ​​calcu...

Do 'enabling technologies' affect customer performance in price-responsive load programs?

International Nuclear Information System (INIS)

Goldman, Charles A.; Kintner-Meyer, Michael; Heffner, Grayson

2002-01-01

Price-responsive load (PRL) programs vary significantly in overall design, the complexity of relationships between program administrators, load aggregators, and customers, and the availability of ''enabling technologies''. Enabling technologies include such features as web-based power system and price monitoring, control and dispatch of curtailable loads, communications and information systems links to program participants, availability of interval metering data to customers in near real time, and building/facility/end-use automation and management capabilities. Two state agencies - NYSERDA in New York and the CEC in California - have been conspicuous leaders in the demonstration of demand response (DR) programs utilizing enabling technologies. In partnership with key stakeholders in these two states (e.g., grid operator, state energy agencies, and program administrators), Lawrence Berkeley National Laboratory (LBNL) and Pacific Northwest National Laboratory (PNNL) surveyed 56 customers who worked with five contractors participating in CEC or NYSERDA-sponsored DR programs. We combined market research and actual load curtailment data when available (i.e., New York) or customer load reduction targets in order to explore the relative importance of contractor's program design features, sophistication of control strategies, and reliance on enabling technologies in predicting customer's ability to deliver load reductions in DR programs targeted to large commercial/industrial customers. We found preliminary evidence that DR enabling technology has a positive effect on load curtailment potential. Many customers indicated that web-based energy information tools were useful for facilitating demand response (e.g., assessing actual performance compared to load reduction contract commitments), that multiple notification channels facilitated timely response, and that support for and use of backup generation allowed customers to achieve significant and predictable load

Three-phase Power Flow Calculation of Low Voltage Distribution Network Considering Characteristics of Residents Load

Science.gov (United States)

Wang, Yaping; Lin, Shunjiang; Yang, Zhibin

2017-05-01

In the traditional three-phase power flow calculation of the low voltage distribution network, the load model is described as constant power. Since this model cannot reflect the characteristics of actual loads, the result of the traditional calculation is always different from the actual situation. In this paper, the load model in which dynamic load represented by air conditioners parallel with static load represented by lighting loads is used to describe characteristics of residents load, and the three-phase power flow calculation model is proposed. The power flow calculation model includes the power balance equations of three-phase (A,B,C), the current balance equations of phase 0, and the torque balancing equations of induction motors in air conditioners. And then an alternating iterative algorithm of induction motor torque balance equations with each node balance equations is proposed to solve the three-phase power flow model. This method is applied to an actual low voltage distribution network of residents load, and by the calculation of three different operating states of air conditioners, the result demonstrates the effectiveness of the proposed model and the algorithm.

Evaluation of dynamic loads induced by transient regimes of fluid flows in the pipe systems and devices of reducing the loads and their effects

International Nuclear Information System (INIS)

Serban, Viorel; Chirita, Alexandru Mihai; Androne, Marian; Alexandru, Constantin; Ciuca, Camelia; Badara, Janina; Alexandru, Carmen

1995-01-01

The paper presents the analytic methods for estimating the dynamic effects induced in pipe systems in transient regimes. They are based on computation programs developed in order to check the behaviour of ECCS and EWS under 'water hammer effect' and the behaviour of the primary circuit system under stresses caused by pipe cracks. Computation examples are presented in order to emphasize the capabilities of the programs to model transient phenomena in complex pipe networks. The overpressure induced by the water hammer effect, as revealed by comparing several transient regimes, depends on the fluid viscosity, the initial speed, the duration of starting the transient regime, the system rigidity, etc. Values several ten times higher that the initial one could be thus reached. An overview of new types of devices designed for damping the effect of water hammer phenomenon, as well as of sustaining supports for pipe systems and equipment able to damp the vibrations produced by the transient regimes of fluid flows and seismic movements is presented. These devices have also to cope with the high shocks produced by pipe breakage as well as high static loads. The paper contains the following sections: 1. Introduction; 2. Evaluating dynamic loads associated to the water hammer phenomenon; 3. Determining loads associated to the water hammer phenomenon for the ECC system of the Cernavoda NPP Unit 1; 4. Device for reducing the water hammer effects; 5. Evaluating dynamic loads associated to pipe cracks; 6. Determining loads associated to pipe cracks in the Cernavoda NPP primary circuit; 7. Devices for absorbing and damping the dynamic loads in pipe systems and equipment; 8. Conclusions. (authors)

Comparison of Building Energy Modeling Programs: Building Loads

Energy Technology Data Exchange (ETDEWEB)

Zhu, Dandan [Tsinghua Univ., Beijing (China); Hong, Tianzhen [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Yan, Da [Tsinghua Univ., Beijing (China); Wang, Chuang [Tsinghua Univ., Beijing (China)

2012-06-01

This technical report presented the methodologies, processes, and results of comparing three Building Energy Modeling Programs (BEMPs) for load calculations: EnergyPlus, DeST and DOE-2.1E. This joint effort, between Lawrence Berkeley National Laboratory, USA and Tsinghua University, China, was part of research projects under the US-China Clean Energy Research Center on Building Energy Efficiency (CERC-BEE). Energy Foundation, an industrial partner of CERC-BEE, was the co-sponsor of this study work. It is widely known that large discrepancies in simulation results can exist between different BEMPs. The result is a lack of confidence in building simulation amongst many users and stakeholders. In the fields of building energy code development and energy labeling programs where building simulation plays a key role, there are also confusing and misleading claims that some BEMPs are better than others. In order to address these problems, it is essential to identify and understand differences between widely-used BEMPs, and the impact of these differences on load simulation results, by detailed comparisons of these BEMPs from source code to results. The primary goal of this work was to research methods and processes that would allow a thorough scientific comparison of the BEMPs. The secondary goal was to provide a list of strengths and weaknesses for each BEMP, based on in-depth understandings of their modeling capabilities, mathematical algorithms, advantages and limitations. This is to guide the use of BEMPs in the design and retrofit of buildings, especially to support China’s building energy standard development and energy labeling program. The research findings could also serve as a good reference to improve the modeling capabilities and applications of the three BEMPs. The methodologies, processes, and analyses employed in the comparison work could also be used to compare other programs. The load calculation method of each program was analyzed and compared to

Load monitoring program: Status and results report. Volume 1: Summary

International Nuclear Information System (INIS)

1994-06-01

British Columbia Hydro conducts a monitoring program to provide information on customer needs and values for planning; to measure customer response, energy savings impacts, and load shape impacts due to changes in rate level, rate restructuring, and Power Smart programs; to estimate end-use consumption and load shapes by customer class; and to provide load information for distribution and system load studies. To achieve these objectives, the monitoring program tracks the characteristics and energy use patterns of a sample of BC Hydro residential, commercial, and industrial customers over a period of several years. The entire sample will be surveyed periodically to obtain information on changes in building characteristics, equipment stocks, and energy-use behavior and attitudes. A report is provided on the status of monitoring program activities and some results obtained in 1993/94. For the residential sector, the results include typical load profiles, end-user demographics, and extent of electric space heating and water heating. In the commercial sector, customers were divided into two main groups. The large-building group was relatively well organized in terms of energy needs and participated in Power Smart programs. The small-building group was relatively energy-inefficient and relatively unaware of Power Smart programs. 43 figs., 15 tabs

A program for calculating load coefficient matrices utilizing the force summation method, L218 (LOADS). Volume 1: Engineering and usage

Science.gov (United States)

Miller, R. D.; Anderson, L. R.

1979-01-01

The LOADS program L218, a digital computer program that calculates dynamic load coefficient matrices utilizing the force summation method, is described. The load equations are derived for a flight vehicle in straight and level flight and excited by gusts and/or control motions. In addition, sensor equations are calculated for use with an active control system. The load coefficient matrices are calculated for the following types of loads: translational and rotational accelerations, velocities, and displacements; panel aerodynamic forces; net panel forces; shears and moments. Program usage and a brief description of the analysis used are presented. A description of the design and structure of the program to aid those who will maintain and/or modify the program in the future is included.

Space station electrical power distribution analysis using a load flow approach

Science.gov (United States)

Emanuel, Ervin M.

1987-01-01

The space station's electrical power system will evolve and grow in a manner much similar to the present terrestrial electrical power system utilities. The initial baseline reference configuration will contain more than 50 nodes or busses, inverters, transformers, overcurrent protection devices, distribution lines, solar arrays, and/or solar dynamic power generating sources. The system is designed to manage and distribute 75 KW of power single phase or three phase at 20 KHz, and grow to a level of 300 KW steady state, and must be capable of operating at a peak of 450 KW for 5 to 10 min. In order to plan far into the future and keep pace with load growth, a load flow power system analysis approach must be developed and utilized. This method is a well known energy assessment and management tool that is widely used throughout the Electrical Power Utility Industry. The results of a comprehensive evaluation and assessment of an Electrical Distribution System Analysis Program (EDSA) is discussed. Its potential use as an analysis and design tool for the 20 KHz space station electrical power system is addressed.

Heel blood flow during loading and off-loading in bedridden older adults with low and normal ankle-brachial pressure index: a quasi-experimental study.

Science.gov (United States)

Masaki, Nami; Sugama, Junko; Okuwa, Mayumi; Inagaki, Misako; Matsuo, Junko; Nakatani, Tosio; Sanada, Hiromi

2013-07-01

The purpose of this study was to evaluate the differences in heel blood flow during loading and off-loading in bedridden adults older than 65 years. The patients were divided into three groups based on ankle-brachial pressure index (ABI) and transcutaneous oxygen tension (tcPO₂): (1) patients with an ABI ≥ 0.8 (Group A); (2) patients with an ABI < 0.8 and heel tcPO₂ ≥ 10 mmHg (Group B); and (3) patients with an ABI < 0.8 and heel tcPO₂ < 10 mmHg (Group C). Heel blood flow was monitored using tcPO₂ sensors. Data were collected with the heel (1) suspended above the bed surface (preload), (2) on the bed surface for 30 min (loading), and (3) again suspended above the bed surface for 60 min (off-loading). Heel blood flow during off-loading was assessed using three parameters: oxygen recovery index (ORI), total tcPO₂ for the first 10 min, and change in tcPO₂ after 60 min of off-loading. ORI in Group C (n = 8) was significantly shorter than in Groups A (n = 22) and B (n = 15). Total tcPO₂ for the first 10 min of off-loading in Group C was significantly less than that in Groups A and B. Change in tcPO₂ after 60 min of off-loading in Group C was less than in Group A. Based on these findings, additional preventive care against heel blood flow decrease in older adults with an ABI < 0.8 and heel tcPO₂ < 10 mmHg might be necessary after loading.

Demand response modeling considering Interruptible/Curtailable loads and capacity market programs

International Nuclear Information System (INIS)

Aalami, H.A.; Moghaddam, M. Parsa; Yousefi, G.R.

2010-01-01

Recently, a massive focus has been made on demand response (DR) programs, aimed to electricity price reduction, transmission lines congestion resolving, security enhancement and improvement of market liquidity. Basically, demand response programs are divided into two main categories namely, incentive-based programs and time-based programs. The focus of this paper is on Interruptible/Curtailable service (I/C) and capacity market programs (CAP), which are incentive-based demand response programs including penalties for customers in case of no responding to load reduction. First, by using the concept of price elasticity of demand and customer benefit function, economic model of above mentioned programs is developed. The proposed model helps the independent system operator (ISO) to identify and employ relevant DR program which both improves the characteristics of the load curve and also be welcome by customers. To evaluate the performance of the model, simulation study has been conducted using the load curve of the peak day of the Iranian power system grid in 2007. In the numerical study section, the impact of these programs on load shape and load level, and benefit of customers as well as reduction of energy consumption are shown. In addition, by using strategy success indices the results of simulation studies for different scenarios are analyzed and investigated for determination of the scenarios priority. (author)

Linear Programming and Network Flows

CERN Document Server

Bazaraa, Mokhtar S; Sherali, Hanif D

2011-01-01

The authoritative guide to modeling and solving complex problems with linear programming-extensively revised, expanded, and updated The only book to treat both linear programming techniques and network flows under one cover, Linear Programming and Network Flows, Fourth Edition has been completely updated with the latest developments on the topic. This new edition continues to successfully emphasize modeling concepts, the design and analysis of algorithms, and implementation strategies for problems in a variety of fields, including industrial engineering, management science, operations research

Computer program for compressible flow network analysis

Science.gov (United States)

Wilton, M. E.; Murtaugh, J. P.

1973-01-01

Program solves problem of an arbitrarily connected one dimensional compressible flow network with pumping in the channels and momentum balancing at flow junctions. Program includes pressure drop calculations for impingement flow and flow through pin fin arrangements, as currently found in many air cooled turbine bucket and vane cooling configurations.

Calculation methods for steadily loaded, off-set pivot, tilting pad thrust bearings. (Guide to use of computer program A9235.)

Science.gov (United States)

1992-12-01

ESDU 92035 provides details of a FORTRAN program that implements the calculation method of ESDU 83004. It allows performance analysis of an existing design, or the design of a bearing dimensions, subject to any space constraint, are recommended. The predicted performance includes the lubricant film thickness under load, its temperature and flow rate, the power loss, and the bearing temperature. Recommendations are also made on surface finish. Warning messages are output in the following cases, for each of which possible remedial actions are suggested: drain or pad temperature too high, churning losses too great, film thickness too small, pad number too high, ratio or inner to outer pad radius too large, flow rate too great, lubricant or pad temperature outside usable range. A lubricant database is provided that may be extended or edited. The program applies to Newtonian lubricants in laminar flow. Worked examples illustrate the use of the program.

Active load reduction using individual pitch, based on local blade flow measurements

DEFF Research Database (Denmark)

Larsen, Torben J.; Aagaard Madsen, H.; Thomsen, K.

2005-01-01

-of-the-art load-reducing concepts. Since the new flow-based concept deviates significantly from previous published load-reducing strategies, a comparison of the performance based on aeroelastic simulations is included. Advantages and drawbacks of the systems are discussed. Copyright (C) 2004 John Wiley Sons, Ltd.......A new load-reducing control strategy for individual blade control of large pitch-controlled wind turbines is presented This control concept is based on local blade inflow measurements and offers the possibility of larger load reductions, without loss of power production, than seen in other state...

Voltage stability analysis using a modified continuation load flow ...

African Journals Online (AJOL)

This paper addresses the rising problem of identifying the voltage stability limits of load buses in a power system and how to optimally place capacitor banks for voltage stability improvement. This paper uses the concept of the continuation power flow analysis used in voltage stability analysis. It uses the modified ...

Comparison of Steady-State SVC Models in Load Flow Calculations

DEFF Research Database (Denmark)

Chen, Peiyuan; Chen, Zhe; Bak-Jensen, Birgitte

2008-01-01

This paper compares in a load flow calculation three existing steady-state models of static var compensator (SVC), i.e. the generator-fixed susceptance model, the total susceptance model and the firing angle model. The comparison is made in terms of the voltage at the SVC regulated bus, equivalent...... SVC susceptance at the fundamental frequency and the load flow convergence rate both when SVC is operating within and on the limits. The latter two models give inaccurate results of the equivalent SVC susceptance as compared to the generator model due to the assumption of constant voltage when the SVC...... is operating within the limits. This may underestimate or overestimate the SVC regulating capability. Two modified models are proposed to improve the SVC regulated voltage according to its steady-state characteristic. The simulation results of the two modified models show the improved accuracy...

The DECADE performance assessment program

International Nuclear Information System (INIS)

Weber, B.V.; Ottinger, P.F.; Commisso, R.J.; Thompson, J.; Rowley, J.E.; Filios, P.; Babineau, M.A.

1996-01-01

Previous analyses of DECADE Module 1 experiments indicated significant current loss between the plasma opening switch (POS) and an electron-beam load. A program was initiated to diagnose and improve the power flow to assess the performance of a multi-module DECADE system. Power flow measurements between the POS and load indicate high vacuum flow, distributed current loss and azimuthal asymmetries. A decreased load impedance reduces the fraction of the load current flowing in vacuum. Improved plasma source symmetry reduces losses near the load for long conduction times. Increased POS impedance is required to significantly improve the power coupling to the load. (author). 6 figs., 9 refs

The DECADE performance assessment program

Energy Technology Data Exchange (ETDEWEB)

Weber, B V; Ottinger, P F; Commisso, R J [Naval Research Lab., Washington, DC (United States). Plasma Physics Div.; Goyer, J R; Kortbawi, D [Physics International Co., Berkeley, CA (United States); Thompson, J [Maxwell Labs., San Diego, CA (United States); Rowley, J E; Filios, P [Defense Nuclear Agency, Alexandria, VA (United States); Babineau, M A [Sverdlup Technology, Tullahoma, TN (United States)

1997-12-31

Previous analyses of DECADE Module 1 experiments indicated significant current loss between the plasma opening switch (POS) and an electron-beam load. A program was initiated to diagnose and improve the power flow to assess the performance of a multi-module DECADE system. Power flow measurements between the POS and load indicate high vacuum flow, distributed current loss and azimuthal asymmetries. A decreased load impedance reduces the fraction of the load current flowing in vacuum. Improved plasma source symmetry reduces losses near the load for long conduction times. Increased POS impedance is required to significantly improve the power coupling to the load. (author). 6 figs., 9 refs.

Power flow control strategy in distribution network for dc type distributed energy resource at load bus

International Nuclear Information System (INIS)

Hanif, A.; Choudhry, M.A.

2013-01-01

This research work presents a feed forward power flow control strategy in the secondary distribution network working in parallel with a DC type distributed energy resource (DER) unit with SPWM-IGBT Voltage Source Converter (VSC). The developed control strategy enables the VSC to be used as power flow controller at the load bus in the presence of utility supply. Due to the investigated control strategy, power flow control from distributed energy resource (DER) to common load bus is such that power flows to the load without facing any power quality problem. The technique has an added advantage of controlling power flow without having a dedicated power flow controller. The SPWM-IGBT VSC is serving the purpose of dc-ac converter as well as power flow controller. Simulations for a test system using proposed power flow control strategy are carried out using SimPower Systems toolbox of MATLAB at the rate and Simulink at the rate. The results show that a reliable, effective and efficient operation of DC type DER unit in coordination with main utility network can be achieved. (author)

Cargo flows distribution over the loading sites of enterprises by using methods of artificial intelligence

Directory of Open Access Journals (Sweden)

Олександр Павлович Кіркін

2017-06-01

Full Text Available Development of information technologies and market requirements in effective control over cargo flows, forces enterprises to look for new ways and methods of automated control over the technological operations. For rail transportation one of the most complicated tasks of automation is the cargo flows distribution over the sites of loading and unloading. In this article the solution with the use of one of the methods of artificial intelligence – a fuzzy inference has been proposed. The analysis of the last publications showed that the fuzzy inference method is effective for the solution of similar tasks, it makes it possible to accumulate experience, it is stable to temporary impacts of the environmental conditions. The existing methods of the cargo flows distribution over the sites of loading and unloading are too simplified and can lead to incorrect decisions. The purpose of the article is to create a distribution model of cargo flows of the enterprises over the sites of loading and unloading, basing on the fuzzy inference method and to automate the control. To achieve the objective a mathematical model of the cargo flows distribution over the sites of loading and unloading has been made using fuzzy logic. The key input parameters of the model are: «number of loading sites», «arrival of the next set of cars», «availability of additional operations». The output parameter is «a variety of set of cars». Application of the fuzzy inference method made it possible to reduce loading time by 15% and to reduce costs for preparatory operations before loading by 20%. Thus this method is an effective means and holds the greatest promise for railway competitiveness increase. Interaction between different types of transportation and their influence on the cargo flows distribution over the sites of loading and unloading hasn’t been considered. These sites may be busy transshipping at that very time which is characteristic of large enterprises

Constant Jacobian Matrix-Based Stochastic Galerkin Method for Probabilistic Load Flow

Directory of Open Access Journals (Sweden)

Yingyun Sun

2016-03-01

Full Text Available An intrusive spectral method of probabilistic load flow (PLF is proposed in the paper, which can handle the uncertainties arising from renewable energy integration. Generalized polynomial chaos (gPC expansions of dependent random variables are utilized to build a spectral stochastic representation of PLF model. Instead of solving the coupled PLF model with a traditional, cumbersome method, a modified stochastic Galerkin (SG method is proposed based on the P-Q decoupling properties of load flow in power system. By introducing two pre-calculated constant sparse Jacobian matrices, the computational burden of the SG method is significantly reduced. Two cases, IEEE 14-bus and IEEE 118-bus systems, are used to verify the computation speed and efficiency of the proposed method.

Developed generalised unified power flow controller model in the Newton–Raphson power-flow analysis using combined mismatches method

DEFF Research Database (Denmark)

Kamel, Salah; Jurado, Francisco; Chen, Zhe

2016-01-01

values are calculated during the iterative process based on the desired controlled values and buses voltage at the terminals of GUPFC. The parameters of GUPFC can be calculated during the iterative process and the final values are updated after load flow convergence. Using the developed GUPFC model......, the original structure and symmetry of the admittance and Jacobian matrices can still be kept, the changing of Jacobian matrix is eliminated. Consequently, the complexities of the computer load flow program codes with GUPFC are reduced. The HPCIM load flow code with the proposed model is written in C......++ programming language. Where, the SuperLU library is utilised to handle the sparse Jacobian matrix. The proposed model has been validated using the standard IEEE test systems....

Review of current Southern California edison load management programs and proposal for a new market-driven, mass-market, demand-response program

Energy Technology Data Exchange (ETDEWEB)

Weller, G.H.

2002-01-01

Utility load management programs, including direct load control and interruptible load programs, constitute a large installed base of controllable loads that are employed by utilities as system reliability resources. In response to energy supply shortfalls expected during the summer of 2001, the California Public Utilities Commission in spring 2001 authorized new utility load management programs as well as revisions to existing programs. This report provides an independent review of the designs of these new programs for a large utility (Southern California Edison) and suggests possible improvements to enhance the price responsiveness of the customer actions influenced by these programs. The report also proposes a new program to elicit a mass-market demand response to utility price signals.

Probabilistic Constrained Load Flow Considering Integration of Wind Power Generation and Electric Vehicles

DEFF Research Database (Denmark)

Vlachogiannis, Ioannis (John)

2009-01-01

A new formulation and solution of probabilistic constrained load flow (PCLF) problem suitable for modern power systems with wind power generation and electric vehicles (EV) demand or supply is represented. The developed stochastic model of EV demand/supply and the wind power generation model...... are incorporated into load flow studies. In the resulted PCLF formulation, discrete and continuous control parameters are engaged. Therefore, a hybrid learning automata system (HLAS) is developed to find the optimal offline control settings over a whole planning period of power system. The process of HLAS...

Load Flow Analysis of Hybrid AC-DC Power System with Offshore Wind Power

DEFF Research Database (Denmark)

Dhua, Debasish; Huang, Shaojun; Wu, Qiuwei

2017-01-01

The offshore wind power has received immense attention because of higher wind speed and lower opposition for construction. A wide range of combinations of high-voltage ACDC transmission have been proposed for integrating offshore wind farms and long-distance power transmission. This paper...... is to model such hybrid AC-DC systems including the interfacing converters, which have several control parameters that can change the load flow of the hybrid systems. Then, the paper proposes a Load Flow algorithm based on the Newton-Raphson method, which covers three different section types...

Flow field and load characteristics of the whole MEXICO wind turbine

DEFF Research Database (Denmark)

Xu, Haoran; Yang, Hua; Liu, Chao

2017-01-01

CFD(Computational Fluid Dynamics) method was used to perform steady numerical simulation investigation on the flow field and load characteristics of MEXICO(Model EXperiment In Controlled cOnditions) wind turbine under non-yawed condition. Circumferentially-Averaged method was used to extract...... characteristics around the blade was analyzed and the points of flow separation were found along the blade, the results show that the points of flow separation move towards trailing edge with the increase of radius. The distribution of vorticity in the wake of MEXICO rotor was also analyzed. The distribution...

Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and prevention programs

Directory of Open Access Journals (Sweden)

Boyi Dai

2014-12-01

Full Text Available Anterior cruciate ligament (ACL injuries are common in soccer. Understanding ACL loading mechanisms and risk factors for ACL injury is critical for designing effective prevention programs. The purpose of this review is to summarize the relevant literature on ACL loading mechanisms, ACL injury risk factors, and current ACL injury prevention programs for soccer players. Literature has shown that tibial anterior translation due to shear force at the proximal end of tibia is the primary ACL loading mechanism. No evidence has been found showing that knee valgus moment is the primary ACL loading mechanism. ACL loading mechanisms are largely ignored in previous studies on risk factors for ACL injury. Identified risk factors have little connections to ACL loading mechanisms. The results of studies on ACL injury prevention programs for soccer players are inconsistent. Current ACL injury prevention programs for soccer players are clinically ineffective due to low compliance. Future studies are urgently needed to identify risk factors for ACL injury in soccer that are connected to ACL loading mechanisms and have cause-and-effect relationships with injury rate, and to develop new prevention programs to improve compliance.

Performance assessment of mass flow rate measurement capability in a large scale transient two-phase flow test system

International Nuclear Information System (INIS)

Nalezny, C.L.; Chapman, R.L.; Martinell, J.S.; Riordon, R.P.; Solbrig, C.W.

1979-01-01

Mass flow is an important measured variable in the Loss-of-Fluid Test (LOFT) Program. Large uncertainties in mass flow measurements in the LOFT piping during LOFT coolant experiments requires instrument testing in a transient two-phase flow loop that simulates the geometry of the LOFT piping. To satisfy this need, a transient two-phase flow loop has been designed and built. The load cell weighing system, which provides reference mass flow measurements, has been analyzed to assess its capability to provide the measurements. The analysis consisted of first performing a thermal-hydraulic analysis using RELAP4 to compute mass inventory and pressure fluctuations in the system and mass flow rate at the instrument location. RELAP4 output was used as input to a structural analysis code SAPIV which is used to determine load cell response. The computed load cell response was then smoothed and differentiated to compute mass flow rate from the system. Comparison between computed mass flow rate at the instrument location and mass flow rate from the system computed from the load cell output was used to evaluate mass flow measurement capability of the load cell weighing system. Results of the analysis indicate that the load cell weighing system will provide reference mass flows more accurately than the instruments now in LOFT

Alternative approach to automated management of load flow in engineering networks considering functional reliability

Directory of Open Access Journals (Sweden)

Ирина Александровна Гавриленко

2016-02-01

Full Text Available The approach to automated management of load flow in engineering networks considering functional reliability was proposed in the article. The improvement of the concept of operational and strategic management of load flow in engineering networks was considered. The verbal statement of the problem for thesis research is defined, namely, the problem of development of information technology for exact calculation of the functional reliability of the network, or the risk of short delivery of purpose-oriented product for consumers

The effects of shoulder load and pinch force on electromyographic activity and blood flow in the forearm during a pinch task

DEFF Research Database (Denmark)

Visser, Bart; Kofoed Nielsen, Pernille; de Kraker, Heleen

2006-01-01

loaded with 4.95 kg each) were combined with intermittent pinch forces at 0, 10 and 25% of the maximum voluntary contraction (MVC). Blood flow to the forearm was measured with Doppler ultrasound. Myoelectric activity of the forearm and neck-shoulder muscles was recorded to check for the workload levels....... Across all levels of shoulder load, blood flow increased significantly with increasing pinch force (21% at 10% MVC and by 44% at 25% MVC). Blood flow was significantly affected by shoulder load, with the lowest blood flow at the highest shoulder load. Interactions of pinch force and shoulder load were....... The results of this study indicate that shoulder load might influence blood flow to the forearm....

Load estimation from planar PIV measurement in vortex dominated flows

Science.gov (United States)

McClure, Jeffrey; Yarusevych, Serhiy

2017-11-01

Control volume-based loading estimates are employed on experimental and synthetic numerical planar Particle Image Velocimetry (PIV) data of a stationary cylinder and a cylinder undergoing one degree-of-freedom (1DOF) Vortex Induced Vibration (VIV). The results reveal the necessity of including out of plane terms, identified from a general formulation of the control volume momentum balance, when evaluating loads from planar measurements in three-dimensional flows. Reynolds stresses from out of plane fluctuations are shown to be significant for both instantaneous and mean force estimates when the control volume encompasses vortex dominated regions. For planar measurement, invoking a divergence-free assumption allows accurate estimation of half the identified terms. Towards evaluating the fidelity of PIV-based loading estimates for obtaining the forcing function unobtrusively in VIV experiments, the accuracy of the control volume-based loading methodology is evaluated using the numerical data with synthetically generated experimental PIV error, and a comparison is made between experimental PIV-based estimates and simultaneous force balance measurements.

EFFECTS OF SLOTTED BLADING ON SECONDARY FLOW IN HIGHLY LOADED COMPRESSOR CASCADE

Directory of Open Access Journals (Sweden)

RAMZI MDOUKI

2013-10-01

Full Text Available With the aim to increase allowable blade loadings and enlarge stable operating range in highly loaded compressor, this work is carried out in order to explore the potential of passive control via slotted bladings in linear cascade configurations under both design and stall conditions. Through an extensive 2D-numerical study, the effects of location, width and slope of slots were analysed and the best configuration was identified. Based on the optimal slot, the 3D aerodynamic performances of cascade were studied and the influence of slotted blading to control endwall flow was investigated. Both 2D and 3D calculations are performed on steady RANS solver with standard k-epsilon turbulence model and low Mach number regime. The total loss coefficient, turning angle and flow visualizations on the blade and end-wall surfaces are adopted to describe the different configurations. The obtained results show, for 2D situation, that a maximum of 28.3% reduction in loss coefficient had been reached and the flow turning was increased with approximately 5°. Concerning 3D flow fields the slots marked their benefit at large incoming flow angles which delays the separation on both end wall and blade suction surface at mid span. However, at design conditions, the slotted blades are not able to control secondary flows near the wall and so, lose their potential.

Mark II containment lead plant program load evaluation and acceptance criteria

International Nuclear Information System (INIS)

1978-10-01

The report, prepared by the Office of Nuclear Reactor Regulation, addresses the portion of the Mark II owner's program that provides a generic methodology for establishing design basis LOCA and safety relief valve loads for the lead Mark II facilities (Zimmer, Shoreham, and LaSalle), i.e., the lead plant program. The report includes an evaluation of the Mark II owner's load methodology, a description of load methodologies that we find acceptable for use in the individual plant unique assessments, and the basis for the stated conclusions

Optimization programs for reactor core fuel loading exhibiting reduced neutron leakage

International Nuclear Information System (INIS)

Darilek, P.

1991-01-01

The program MAXIM was developed for the optimization of the fuel loading of WWER-440 reactors. It enables the reactor core reactivity to be maximized by modifying the arrangement of the fuel assemblies. The procedure is divided into three steps. The first step includes the passage from the three-dimensional model of the reactor core to the two-dimensional model. In the second step, the solution to the problem is sought assuming that the multiplying properties, or the reactivity in the zones of the core, vary continuously. In the third step, parameters of actual fuel assemblies are inserted in the ''continuous'' solution obtained. Combined with the program PROPAL for a detailed refinement of the loading, the program MAXIM forms a basis for the development of programs for the optimization of fuel loading with burnable poisons. (Z.M.). 16 refs

PROBABILISTIC FLOW DISTRIBUTION AS A REACTION TO THE STOCHASTICITY OF THE LOAD IN THE POWER SYSTEM

Directory of Open Access Journals (Sweden)

A. M. Hashimov

2016-01-01

Full Text Available For the analysis and control of power systems deterministic approaches that are implemented in the form of well-known methods and models of calculation of steady-state and transient modes are mostly use in current practice. With the use of these methods it is possible to obtain solutions only for fixed circuit parameters of the system scheme and assuming that active and reactive powers as well as generation in nodal points of the network remain the same. In reality the stochastic character of power consumption cause the casual fluctuations of voltages at the nodes and power flows in electric power lines of the power system. Such casual fluctuations of operation can be estimated with the use of probabilistic simulation of the power flows. In the article the results of research of the influence of depth of casual fluctuations of the load power of the system on the probability distribution of voltage at nodes as well as on the flows of active and reactive power in the lines are presented. Probabilistic modeling of flow under stochastic load change is performed for different levels of fluctuations and under loading of the mode of the system up to peak load power. Test study to quantify the effect of stochastic variability of loads on the probabilistic distribution parameters of the modes was carried out on behalf of the electrical network of the real power system. The results of the simulation of the probability flow distribution for these fluctuations of the load, represented in the form of discrete sample values of the active power obtained with the use of the analytical Monte-Carlo method, and real data measurements of their values in the network under examination were compared.

Software defined networks reactive flow programming and load balance switching

OpenAIRE

Καλλιανιώτης, Νικόλαος; Kallianiotis, Nikolaos

2017-01-01

This project serves as a Master Thesis as the requirements of the master’s programme Master of Digital Communications and Networks. It proposes load balancing algorithms applied to Software-Defined Networks to achieve the best possible resource utilisation of each of the links present in a network. The open-sources Opendaylight project and Floodlight project are used as SDN controllers, and the network is emulated using Mininet software

Construction of estimated flow- and load-duration curves for Kentucky using the Water Availability Tool for Environmental Resources (WATER)

Science.gov (United States)

Unthank, Michael D.; Newson, Jeremy K.; Williamson, Tanja N.; Nelson, Hugh L.

2012-01-01

Flow- and load-duration curves were constructed from the model outputs of the U.S. Geological Survey's Water Availability Tool for Environmental Resources (WATER) application for streams in Kentucky. The WATER application was designed to access multiple geospatial datasets to generate more than 60 years of statistically based streamflow data for Kentucky. The WATER application enables a user to graphically select a site on a stream and generate an estimated hydrograph and flow-duration curve for the watershed upstream of that point. The flow-duration curves are constructed by calculating the exceedance probability of the modeled daily streamflows. User-defined water-quality criteria and (or) sampling results can be loaded into the WATER application to construct load-duration curves that are based on the modeled streamflow results. Estimates of flow and streamflow statistics were derived from TOPographically Based Hydrological MODEL (TOPMODEL) simulations in the WATER application. A modified TOPMODEL code, SDP-TOPMODEL (Sinkhole Drainage Process-TOPMODEL) was used to simulate daily mean discharges over the period of record for 5 karst and 5 non-karst watersheds in Kentucky in order to verify the calibrated model. A statistical evaluation of the model's verification simulations show that calibration criteria, established by previous WATER application reports, were met thus insuring the model's ability to provide acceptably accurate estimates of discharge at gaged and ungaged sites throughout Kentucky. Flow-duration curves are constructed in the WATER application by calculating the exceedence probability of the modeled daily flow values. The flow-duration intervals are expressed as a percentage, with zero corresponding to the highest stream discharge in the streamflow record. Load-duration curves are constructed by applying the loading equation (Load = Flow*Water-quality criterion) at each flow interval.

Flow performance of highly loaded axial fan with bowed rotor blades

Science.gov (United States)

Chen, L.; Liu, X. J.; Yang, A. L.; Dai, R.

2013-12-01

In this paper, a partial bowed rotor blade was proposed for a newly designed high loaded axial fan. The blade was positively bowed 30 degrees from hub to 30 percent spanwise position. Flows of radial blade and bowed blade fans were numerically compared for various operation conditions. Results show that the fan's performance is improved. At the designed condition with flow coefficient of 0.52, the efficiency of the bowed blade fan is increased 1.44% and the static pressure rise is increased 11%. Comparing the flow structures, it can be found that the separated flow in the bowed fan is reduced and confined within 20 percent span, which is less than the 35 percent in the radial fan. It means that the bowed blade generates negative blade force and counteracts partial centrifugal force. It is alleviates the radial movements of boundary layers in fan's hub region. Flow losses due to 3D mixing are reduced in the rotor. Inlet flow to downstream stator is also improved.

Investigation of the Flow Field and Performances of a Centrifugal Pump at Part Load

Science.gov (United States)

Prunières, R.; Inoue, Y.; Nagahara, T.

2016-11-01

Centrifugal pump performance curve instability, characterized by a local dent at part load, can be the consequence of flow instabilities in rotating or stationary parts. Such flow instabilities often result in abnormal operating conditions which can damage both the pump and the system. In order for the pump to have reliable operation over a wide flow rate range, it is necessary to achieve a design free of instability. The present paper focuses on performance curve instability of a centrifugal pump of mid specific speed (ωs = 0.65) for which instability was observed at part load during tests. The geometry used for this research consist of the first stage of a multi-stage centrifugal pump and is composed of a suction bend, a closed-type impeller, a vaned diffuser and return guide vanes. In order to analyse the instability phenomenon, PIV and CFD analysis were performed. Both methods qualitatively agree relatively well. It appears that the main difference before and after head drop is an increase of reverse flow rate at the diffuser passage inlet on the hub side. This reverse flow decreases the flow passing area at the diffuser passage inlet, disallowing effective flow deceleration and impairing static pressure recovery.

Numerical 3D flow simulation of attached cavitation structures at ultrasonic horn tips and statistical evaluation of flow aggressiveness via load collectives

Science.gov (United States)

Mottyll, S.; Skoda, R.

2015-12-01

A compressible inviscid flow solver with barotropic cavitation model is applied to two different ultrasonic horn set-ups and compared to hydrophone, shadowgraphy as well as erosion test data. The statistical analysis of single collapse events in wall-adjacent flow regions allows the determination of the flow aggressiveness via load collectives (cumulative event rate vs collapse pressure), which show an exponential decrease in agreement to studies on hydrodynamic cavitation [1]. A post-processing projection of event rate and collapse pressure on a reference grid reduces the grid dependency significantly. In order to evaluate the erosion-sensitive areas a statistical analysis of transient wall loads is utilised. Predicted erosion sensitive areas as well as temporal pressure and vapour volume evolution are in good agreement to the experimental data.

Estimating the Impacts of Direct Load Control Programs Using GridPIQ, a Web-Based Screening Tool

Energy Technology Data Exchange (ETDEWEB)

Pal, Seemita; Thayer, Brandon L.; Barrett, Emily L.; Studarus, Karen E.

2017-11-13

In direct load control (DLC) programs, utilities can curtail the demand of participating loads to contractually agreed-upon levels during periods of critical peak load, thereby reducing stress on the system, generation cost, and required transmission and generation capacity. Participating customers receive financial incentives. The impacts of implementing DLC programs extend well beyond peak shaving. There may be a shift of load proportional to the interrupted load to the times before or after a DLC event, and different load shifts have different consequences. Tools that can quantify the impacts of such programs on load curves, peak demand, emissions, and fossil fuel costs are currently lacking. The Grid Project Impact Quantification (GridPIQ) screening tool includes a Direct Load Control module, which takes into account project-specific inputs as well as the larger system context in order to quantify the impacts of a given DLC program. This allows users (utilities, researchers, etc.) to test and compare different program specifications and their impacts.

Effective flow-accelerated corrosion programs in nuclear facilities

International Nuclear Information System (INIS)

Esselman, Thomas C.; McBrine, William J.

2004-01-01

Piping Flow-Accelerated Corrosion Programs in nuclear power generation facilities are classically comprised of the selection of inspection locations with the assistance of a predictive methodology such as the Electric Power Research Institute computer codes CHECMATE or CHECWORKS, performing inspections, conducting structural evaluations on the inspected components, and implementing the appropriate sample expansion and corrective actions. Performing such a sequence of steps can be effective in identifying thinned components and implementing appropriate short term and long term actions necessary to resolve flow-accelerated corrosion related problems. A maximally effective flow-accelerated corrosion (FAC) program requires an understanding of many programmatic details. These include the procedural control of the program, effective use of historical information, managing the activities performed during a limited duration outage, allocating resources based on risk allocation, having an acute awareness of how the plant is operated, investigating components removed from the plant, and several others. This paper will describe such details and methods that will lead to a flow-accelerated corrosion program that effectively minimizes the risk of failure due to flow-accelerated corrosion and provide full and complete documentation of the program. (author)

Effects of external pressure loading on human skin blood flow measured by 133Xe clearance

International Nuclear Information System (INIS)

Holloway, G.A. Jr.; Daly, C.H.; Kennedy, D.; Chimoskey, J.

1976-01-01

Forearm skin blood flow was measured during external pressure loading in normal human subjects using 133 Xe washout from intracutaneous injection sites. Pressures ranging between 5 and 150 mmHg were applied through a 3-cm-diameter disc placed over the site of flow determination. The pressure was maintained constant by a servo-controlled loading mechanism. Flow decreased with pressures from 5 to 10 and 30 to 150 mmHg, but remained constant with pressures from 10 to 30 mmHg. Reactive hyperemia occurred following removal of pressures of 90 mmHg or greater, but did not occur following removal of lower pressures. The pressure-flow curve for parasacral skin of paraplegic subjects closely paralleled the pressure-flow curve of normal skin at pressures tested: 5 to 15 mmHg. These data are interpreted to demonstrate autoregulation of skin blood flow. Autoregulation in parasacral skin of paraplegic subjects suggests a peripheral mechanism. The occurrence of hyperemia at pressures which exceed the ability of skin to autoregulate suggests that both autoregulation and post occlusion hyperemia may have the same mechanism

Estimating Bus Loads and OD Flows Using Location-Stamped Farebox and Wi-Fi Signal Data

Directory of Open Access Journals (Sweden)

Yuxiong Ji

2017-01-01

Full Text Available Electronic fareboxes integrated with Automatic Vehicle Location (AVL systems can provide location-stamped records to infer passenger boarding at individual stops. However, bus loads and Origin-Destination (OD flows, which are useful for route planning, design, and real-time controls, cannot be derived directly from farebox data. Recently, Wi-Fi sensors have been used to collect passenger OD flow information. But the data are insufficient to capture the variation of passenger demand across bus trips. In this study, we propose a hierarchical Bayesian model to estimate trip-level OD flow matrices and a period-level OD flow matrix using sampled OD flow data collected by Wi-Fi sensors and boarding data provided by fareboxes. Bus loads on each bus trip are derived directly from the estimated trip-level OD flow matrices. The proposed method is evaluated empirically on an operational bus route and the results demonstrate that it provides good and detailed transit route-level passenger demand information by combining farebox and Wi-Fi signal data.

Calculation of loading on pipes during filling processes

International Nuclear Information System (INIS)

Thiele, Thomas; Swidersky, Harald

2013-01-01

Filling processes in pipe systems do normally not belong to load design cases for which the integrity of pipelines and their mountings are verified with fluid- and structure-dynamic analysis. However, their frequency of occurrence is several times higher than those of the postulated incident-induced transients. That is why they have to be taken into consideration within fatigue analysis. The loading on pipes or rather on their mountings during filling processes originates from differences in the density of the transported fluids, e.g. at transport of gas slugs within water flow. The exposure time of the flow momentum force is fixed by the height of the flow velocity and by the length of discontinuities in the pipeline sections. Filling procedures frequently end with a pressure surge which was caused by the impingement and decelaration of the water plug at orifices in pipe systems. The calculation of such processes with 1D fluid-dynamic or rather thermal-hydraulic programs requires an idealization of the real form of the two phase flow or respectively of the two phase interface. In the past, several two phase flow regime maps were developed and implemented in codes for this. In this paper, the applicability of the thermo-hydraulic program RELAP5/MOD3.3 which is established in nuclear engineering is examined in order to calculate realistic loads from plug flows during the filling processes. For this, post-test calculations of experiments have been performed and the results have been compared with the experimental results as well as with the classical analytical approach according to Joukowsky. The comparison shows that, dependent on the discretization, the calculated loads are indeed partly underestimated, though the calculation results according to the Joukowsky-approach lie above the measurements. (orig.)

Flow performance of highly loaded axial fan with bowed rotor blades

International Nuclear Information System (INIS)

Chen, L; Liu, X J; Yang, A L; Dai, R

2013-01-01

In this paper, a partial bowed rotor blade was proposed for a newly designed high loaded axial fan. The blade was positively bowed 30 degrees from hub to 30 percent spanwise position. Flows of radial blade and bowed blade fans were numerically compared for various operation conditions. Results show that the fan's performance is improved. At the designed condition with flow coefficient of 0.52, the efficiency of the bowed blade fan is increased 1.44% and the static pressure rise is increased 11%. Comparing the flow structures, it can be found that the separated flow in the bowed fan is reduced and confined within 20 percent span, which is less than the 35 percent in the radial fan. It means that the bowed blade generates negative blade force and counteracts partial centrifugal force. It is alleviates the radial movements of boundary layers in fan's hub region. Flow losses due to 3D mixing are reduced in the rotor. Inlet flow to downstream stator is also improved

Modeling of unified power quality conditioner (UPQC) in distribution systems load flow

International Nuclear Information System (INIS)

Hosseini, M.; Shayanfar, H.A.; Fotuhi-Firuzabad, M.

2009-01-01

This paper presents modeling of unified power quality conditioner (UPQC) in load flow calculations for steady-state voltage compensation. An accurate model for this device is derived to use in load flow calculations. The rating of this device as well as direction of reactive power injection required to compensate voltage to the desired value (1 p.u.) is derived and discussed analytically and mathematically using phasor diagram method. Since performance of the compensator varies when it reaches to its maximum capacity, modeling of UPQC in its maximum rating of reactive power injection is derived. The validity of the proposed model is examined using two standard distribution systems consisting of 33 and 69 nodes, respectively. The best location of UPQC for under voltage problem mitigation in the distribution network is determined. The results show the validity of the proposed model for UPQC in large distribution systems.

Modeling of unified power quality conditioner (UPQC) in distribution systems load flow

Energy Technology Data Exchange (ETDEWEB)

Hosseini, M.; Shayanfar, H.A. [Center of Excellence for Power System Automation and Operation, Department of Electrical Engineering, Iran University of Science and Technology, Tehran (Iran); Fotuhi-Firuzabad, M. [Department of Electrical Engineering, Sharif University of Technology, Tehran (Iran)

2009-06-15

This paper presents modeling of unified power quality conditioner (UPQC) in load flow calculations for steady-state voltage compensation. An accurate model for this device is derived to use in load flow calculations. The rating of this device as well as direction of reactive power injection required to compensate voltage to the desired value (1 p.u.) is derived and discussed analytically and mathematically using phasor diagram method. Since performance of the compensator varies when it reaches to its maximum capacity, modeling of UPQC in its maximum rating of reactive power injection is derived. The validity of the proposed model is examined using two standard distribution systems consisting of 33 and 69 nodes, respectively. The best location of UPQC for under voltage problem mitigation in the distribution network is determined. The results show the validity of the proposed model for UPQC in large distribution systems. (author)

An Examination of Game-Based Learning from Theories of Flow Experience and Cognitive Load

Science.gov (United States)

Lai, Chih-Hung; Chu, Chih-Ming; Liu, Hsiang-Hsuan; Yang, Shun-Bo; Chen, Wei-Hsuan

2013-01-01

This study aims to discuss whether game-based learning with the integration of games and digital learning could enhance not only the flow experience in learning but achieve the same flow experience in pure games. In addition, the authors discovered that whether the game-based learning could make learners to reveal higher cognitive load. The…

Effects of bed-load movement on flow resistance over bed forms

Indian Academy of Sciences (India)

Abstract. The effect of bed-load transport on flow resistance of alluvial channels with undulated bed was experimentally investigated. The experiments were carried out in a tilting flume 250mm wide and 12·5m long with glass-sides of rectan- gular cross-section and artificial dune shaped floor that was made from Plexi-glass.

The NASA Low-Pressure Turbine Flow Physics Program: A Review

Science.gov (United States)

Ashpis, David E.

2002-01-01

An overview of the NASA Glenn Low-Pressure Turbine (LPT) Flow Physics Program will be presented. The flow in the LPT is unique for the gas turbine. It is characterized by low Reynolds number and high freestream turbulence intensity and is dominated by interplay of three basic mechanisms: transition, separation and wake interaction. The flow of most interest is on the suction surface, where large losses are generated due to separation. The LPT is a large, multistage, heavy, jet engine component that suffers efficiency degradation between takeoff and cruise conditions due to decrease in Reynolds number with altitude. The performance penalty is around 2 points for large commercial bypass engines and as much as 7 points for small, high cruise altitude, military engines. The gas-turbine industry is very interested in improving the performance of the LPT and in reducing its weight, part count and cost. Many improvements can be accomplished by improved airfoil design, mainly by increasing the airfoil loading that can yield reduction of airfoils and improved performance. In addition, there is a strong interest in reducing the design cycle time and cost. Key enablers of the needed improvements are computational tools that can accurately predict LPT flows. Current CFD tools in use cannot yet satisfactorily predict the unsteady, transitional and separated flow in the LPT. The main reasons are inadequate transition & turbulence models and incomplete understanding of the LPT flow physics. NASA Glenn has established its LPT program to answer these needs. The main goal of the program is to develop and assess models for unsteady CFD of LPT flows. An approach that consists of complementing and augmenting experimental and computational work elements has been adopted. The work is performed in-house and by several academic institutions, in cooperation and interaction with industry. The program was reviewed at the Minnowbrook II meeting in 1997. This review will summarize the progress

Experimentally determined distribution of granular-flow characteristics in collisional bed load transport

Directory of Open Access Journals (Sweden)

Matoušek Václav

2018-01-01

Full Text Available A series of laboratory experiments on turbulent open-channel two-phase flow in a form of intense bed load transport is reported. Measurements in a laboratory tilting flume included camera based imaging techniques to identify the structure of the flow at the local level. Obtained experimental distributions of two-phase flow related parameters - granular velocity, concentration, and temperature - across a collisional transport layer are discussed. The results are analysed together with additional measured quantities (discharges of mixture and grains, flow depth, bed slope etc. Our major goal is to evaluate the distribution of granular stresses across the transport layer with a special attention paid to the interface between the transport layer and the bed. Furthermore, comparisons are discussed between the experimental results and predictions produced by suitable kinetic-theory based models.

Using wind speed from a blade-mounted flow sensor for power and load assessment on modern wind turbines

DEFF Research Database (Denmark)

Pedersen, Mads M.; Larsen, Torben J.; Madsen, Helge Aa

2017-01-01

In this paper an alternative method to evaluate power performance and loads on wind turbines using a blade-mounted flow sensor is investigated. The hypothesis is that the wind speed measured at the blades has a high correlation with the power and loads such that a power or load assessment can...... be performed from a few hours or days of measurements. In the present study a blade-mounted five-hole pitot tube is used as the flow sensor as an alternative to the conventional approach, where the reference wind speed is either measured at a nearby met mast or on the nacelle using lidar technology or cup...... anemometers. From the flow sensor measurements, an accurate estimate of the wind speed at the rotor plane can be obtained. This wind speed is disturbed by the presence of the wind turbine, and it is therefore different from the free-flow wind speed. However, the recorded wind speed has a high correlation...

Unsteady flow damping force prediction of MR dampers subjected to sinusoidal loading

Science.gov (United States)

Yu, M.; Wang, S. Q.; Fu, J.; Peng, Y. X.

2013-02-01

So far quasi-steady models are usually used to design magnetorheological (MR) dampers, but these models are not sufficient to describe the MR damper behavior under unsteady dynamic loading, for fluid inertia is neglected in quasi-steady models, which will bring more error between computer simulation and experimental results. Under unsteady flow model, the fluid inertia terms will bring error calculated upto 10%, so it is necessary to be considered in the governing equation. In this paper, force-stroke behavior of MR damper with flow mode due to sinusoidal loading excitation is mainly investigated, to simplify the analysis, the one-dimensional axisymmetric annular duct geometry of MR dampers is approximated as a rectangular duct. The rectangular duct can be divided into 3 regions for the velocity profile of the incompressible MR fluid flow, in each region, a partial differential equation is composed of by Navier-Stokes equations, boundary conditions and initial conditions to determine the velocity solution. In addition, in this work, not only Bingham plastic model but the Herschel—Bulkley model is adopted to analyze the MR damper performance. The damping force resulting from the pressure drop of unsteady MR dampers can be obtained and used to design or size MR dampers. Compared with the quasi-steady flow damping force, the damping force of unsteady MR dampers is more close to practice, particularly for the high-speed unsteady movement of MR dampers.

Unsteady flow damping force prediction of MR dampers subjected to sinusoidal loading

International Nuclear Information System (INIS)

Yu, M; Fu, J; Wang, S Q; Peng, Y X

2013-01-01

So far quasi-steady models are usually used to design magnetorheological (MR) dampers, but these models are not sufficient to describe the MR damper behavior under unsteady dynamic loading, for fluid inertia is neglected in quasi-steady models, which will bring more error between computer simulation and experimental results. Under unsteady flow model, the fluid inertia terms will bring error calculated upto 10%, so it is necessary to be considered in the governing equation. In this paper, force-stroke behavior of MR damper with flow mode due to sinusoidal loading excitation is mainly investigated, to simplify the analysis, the one-dimensional axisymmetric annular duct geometry of MR dampers is approximated as a rectangular duct. The rectangular duct can be divided into 3 regions for the velocity profile of the incompressible MR fluid flow, in each region, a partial differential equation is composed of by Navier-Stokes equations, boundary conditions and initial conditions to determine the velocity solution. In addition, in this work, not only Bingham plastic model but the Herschel—Bulkley model is adopted to analyze the MR damper performance. The damping force resulting from the pressure drop of unsteady MR dampers can be obtained and used to design or size MR dampers. Compared with the quasi-steady flow damping force, the damping force of unsteady MR dampers is more close to practice, particularly for the high-speed unsteady movement of MR dampers.

The Effects of Supplementary Low-Load Blood Flow Restriction Training on Morphological and Performance-Based Adaptations in Team Sport Athletes.

Science.gov (United States)

Scott, Brendan R; Peiffer, Jeremiah J; Goods, Paul S R

2017-08-01

Scott, BR, Peiffer, JJ, and Goods, PSR. The effects of supplementary low-load blood flow restriction training on morphological and performance-based adaptations in team sport athletes. J Strength Cond Res 31(8): 2147-2154, 2017-Low-load resistance training with blood flow restriction (BFR) may be a method to enhance muscular development even in trained athletes. This study aimed to assess whether supplemental low-load BFR training can improve muscle size, strength, and physical performance characteristics in team sport athletes. Twenty-one semiprofessional Australian football athletes were assessed for 3-repetition maximum (3RM) and muscular endurance in the back squat, vastus lateralis muscle architecture, and performance in sprint and vertical jump tasks. Participants then undertook a 5-week training program, consisting of normal high-load resistance training supplemented by low-load squats with (LLBFR) or without (LL) BFR. Participants also performed regular conditioning and football training during this period. After the training intervention, participants again completed the pretraining testing battery. Squat 3RM and endurance increased from pretraining levels in both LL (3RM = 12.5% increase; endurance = 24.1% increase; p ≤ 0.007) and LLBFR (3RM = 12.3% increase; endurance = 21.2% increase; p = 0.007) groups, though there were no between-group differences. No post-training changes were observed for muscle architecture, or performance in sprinting and jumping tasks. Although squat 3RM and endurance performance increased in both groups, adding BFR during supplemental exercise did not enhance these responses. Similarly, there were no large differences in the assessments of sprint, acceleration, and jumping performance between the groups after training. These findings suggest that although LLBFR did not negatively affect adaptive responses to resistance training, this training strategy may not provide added benefit for healthy Australian football athletes

A New Wind Turbine Generating System Model for Balanced and Unbalanced Distribution Systems Load Flow Analysis

Directory of Open Access Journals (Sweden)

Ahmet Koksoy

2018-03-01

Full Text Available Wind turbine generating systems (WTGSs, which are conventionally connected to high voltage transmission networks, have frequently been employed as distributed generation units in today’s distribution networks. In practice, the distribution networks always have unbalanced bus voltages and line currents due to uneven distribution of single or double phase loads over three phases and asymmetry of the lines, etc. Accordingly, in this study, for the load flow analysis of the distribution networks, Conventional Fixed speed Induction Generator (CFIG based WTGS, one of the most widely used WTGS types, is modelled under unbalanced voltage conditions. The Developed model has active and reactive power expressions in terms of induction machine impedance parameters, terminal voltages and input power. The validity of the Developed model is confirmed with the experimental results obtained in a test system. The results of the slip calculation based phase-domain model (SCP Model, which was previously proposed in the literature for CFIG based WTGSs under unbalanced voltages, are also given for the comparison. Finally, the Developed model and the SCP model are implemented in the load flow analysis of the IEEE 34 bus test system with the CFIG based WTGSs and unbalanced loads. Thus, it is clearly pointed out that the results of the load flow analysis implemented with both models are very close to each other, and the Developed model is computationally more efficient than the SCP model.

Ground-water discharge and base-flow nitrate loads of nontidal streams, and their relation to a hydrogeomorphic classification of the Chesapeake Bay Watershed, middle Atlantic Coast

Science.gov (United States)

Bachman, L. Joseph; Lindsey, Bruce D.; Brakebill, John W.; Powars, David S.

1998-01-01

Existing data on base-flow and groundwater nitrate loads were compiled and analyzed to assess the significance of groundwater discharge as a source of the nitrate load to nontidal streams of the Chesapeake Bay watershed. These estimates were then related to hydrogeomorphic settings based on lithology and physiographic province to provide insight on the areal distribution of ground-water discharge. Base-flow nitrate load accounted for 26 to about 100 percent of total-flow nitrate load, with a median value of 56 percent, and it accounted for 17 to 80 percent of total-flow total-nitrogen load, with a median value of 48 percent. Hydrograph separations were conducted on continuous streamflow records from 276 gaging stations within the watershed. The values for base flow thus calculated were considered an estimate of ground-water discharge. The ratio of base flow to total flow provided an estimate of the relative importance of ground-water discharge within a basin. Base-flow nitrate loads, total-flow nitrate loads, and total-flow total-nitrogen loads were previously computed from water-quality and discharge measurements by use of a regression model. Base-flow nitrate loads were available from 78 stations, total-flow nitrate loads were available from 86 stations, and total-flow total-nitrogen loads were available for 48 stations. The percentage of base-flow nitrate load to total-flow nitrate load could be computed for 57 stations, whereas the percentage of base-flow nitrate load to totalflow total-nitrogen load could be computed for 36 stations. These loads were divided by the basin area to obtain yields, which were used to compare the nitrate discharge from basins of different sizes. The results indicate that ground-water discharge is a significant source of water and nitrate to the total streamflow and nitrate load. Base flow accounted for 16 to 92 percent of total streamflow at the 276 sampling sites, with a median value of 54 percent. It is estimated that of the 50

Bed Load Variability and Morphology of Gravel Bed Rivers Subject to Unsteady Flow: A Laboratory Investigation

Science.gov (United States)

Redolfi, M.; Bertoldi, W.; Tubino, M.; Welber, M.

2018-02-01

Measurement and estimation of bed load transport in gravel bed rivers are highly affected by its temporal fluctuations. Such variability is primarily driven by the flow regime but is also associated with a variety of inherent channel processes, such as flow turbulence, grain entrainment, and bed forms migration. These internal and external controls often act at comparable time scales, and are therefore difficult to disentangle, thus hindering the study of bed load variability under unsteady flow regime. In this paper, we report on laboratory experiments performed in a large, mobile bed flume where typical hydromorphological conditions of gravel bed rivers were reproduced. Data from a large number of replicated runs, including triangular and square-wave hydrographs, were used to build a statistically sound description of sediment transport processes. We found that the inherent variability of bed load flux strongly depends on the sampling interval, and it is significantly higher in complex, wandering or braided channels. This variability can be filtered out by computing the mean response over the experimental replicates, which allows us to highlight two distinctive phenomena: (i) an overshooting (undershooting) response of the mean bed load flux to a sudden increase (decrease) of discharge, and (ii) a clockwise hysteresis in the sediment rating curve. We then provide an interpretation of these findings through a conceptual mathematical model, showing how both phenomena are associated with a lagging morphological adaptation to unsteady flow. Overall, this work provides basic information for evaluating, monitoring, and managing gravel transport in morphologically active rivers.

Adapting high-level language programs for parallel processing using data flow

Science.gov (United States)

Standley, Hilda M.

1988-01-01

EASY-FLOW, a very high-level data flow language, is introduced for the purpose of adapting programs written in a conventional high-level language to a parallel environment. The level of parallelism provided is of the large-grained variety in which parallel activities take place between subprograms or processes. A program written in EASY-FLOW is a set of subprogram calls as units, structured by iteration, branching, and distribution constructs. A data flow graph may be deduced from an EASY-FLOW program.

Axial-Flow Turbine Rotor Discharge-Flow Overexpansion and Limit-Loading Condition, Part I: Computational Fluid Dynamics (CFD) Investigation

Science.gov (United States)

Chen, Shu-Cheng S.

2017-01-01

A Computational Fluid Dynamic (CFD) investigation is conducted over a two-dimensional axial-flow turbine rotor blade row to study the phenomena of turbine rotor discharge flow overexpansion at subcritical, critical, and supercritical conditions. Quantitative data of the mean-flow Mach numbers, mean-flow angles, the tangential blade pressure forces, the mean-flow mass flux, and the flow-path total pressure loss coefficients, averaged or integrated across the two-dimensional computational domain encompassing two blade-passages, are obtained over a series of 14 inlet-total to exit-static pressure ratios, from 1.5 (un-choked; subcritical condition) to 10.0 (supercritical with excessively high pressure ratio.) Detailed flow features over the full domain-of-computation, such as the streamline patterns, Mach contours, pressure contours, blade surface pressure distributions, etc. are collected and displayed in this paper. A formal, quantitative definition of the limit loading condition based on the channel flow theory is proposed and explained. Contrary to the comments made in the historical works performed on this subject, about the deficiency of the theoretical methods applied in analyzing this phenomena, using modern CFD method for the study of this subject appears to be quite adequate and successful. This paper describes the CFD work and its findings.

Calculation of piping loads due to filling procedures

International Nuclear Information System (INIS)

Swidersky, Harald; Thiele, Thomas

2012-01-01

Filling procedures in piping systems are usually not load cases that are studied by fluid dynamic and structure dynamic analyses with respect to the integrity of pipes and supports. Although, their frequency is higher than that of postulated accidental transients, therefore they have to be considered for fatigue analyses. The piping and support loads due to filling procedures are caused by the density differences if the transported fluids, for instance in flows with the transport of gas bubbles. The impact duration of the momentum forces is defined by the flow velocity and the length of discontinuities in the piping segments. Filling procedures end very often with a shock pressure, caused by the impact and decelerating of the fluid front at smaller cross sections. The suitability of the thermally hydraulics program RELAP/MOD3.3 for the calculation of realistic loads from filling procedures was studied, the results compared with experimental data. It is shown that dependent on the discretization level the loads are partial significantly underestimated.

Silicon microfluidic flow focusing devices for the production of size-controlled PLGA based drug loaded microparticles.

Science.gov (United States)

Keohane, Kieran; Brennan, Des; Galvin, Paul; Griffin, Brendan T

2014-06-05

The increasing realisation of the impact of size and surface properties on the bio-distribution of drug loaded colloidal particles has driven the application of micro fabrication technologies for the precise engineering of drug loaded microparticles. This paper demonstrates an alternative approach for producing size controlled drug loaded PLGA based microparticles using silicon Microfluidic Flow Focusing Devices (MFFDs). Based on the precise geometry and dimensions of the flow focusing channel, microparticle size was successfully optimised by modifying the polymer type, disperse phase (Qd) flow rate, and continuous phase (Qc) flow rate. The microparticles produced ranged in sizes from 5 to 50 μm and were highly monodisperse (coefficient of variation <5%). A comparison of Ciclosporin (CsA) loaded PLGA microparticles produced by MFFDs vs conventional production techniques was also performed. MFFDs produced microparticles with a narrower size distribution profile, relative to the conventional approaches. In-vitro release kinetics of CsA was found to be influenced by the production technique, with the MFFD approach demonstrating the slowest rate of release over 7 days (4.99 ± 0.26%). Finally, MFFDs were utilised to produce pegylated microparticles using the block co-polymer, PEG-PLGA. In contrast to the smooth microparticles produced using PLGA, PEG-PLGA microparticles displayed a highly porous surface morphology and rapid CsA release, with 85 ± 6.68% CsA released after 24h. The findings from this study demonstrate the utility of silicon MFFDs for the precise control of size and surface morphology of PLGA based microparticles with potential drug delivery applications. Copyright © 2014 Elsevier B.V. All rights reserved.

Influence of upstream disturbance on the draft-tube flow of Francis turbine under part-load conditions

Science.gov (United States)

Chen, Ting; Zheng, Xianghao; Zhang, Yu-ning; Li, Shengcai

2018-02-01

Owing to the part-load operations for the enhancement of grid flexibility, the Francis turbine often suffers from severe low-frequency and large-amplitude hydraulic instability, which is mostly pertinent to the highly unsteady swirling vortex rope in the draft tube. The influence of disturbances in the upstream (e.g., large-scale vortex structures in the spiral casing) on the draft-tube vortex flow is not well understood yet. In the present paper, the influence of the upstream disturbances on the vortical flow in the draft tube is studied based on the vortex identification method and the analysis of several important parameters (e.g., the swirl number and the velocity profile). For a small guide vane opening (representing the part-load condition), the vortices triggered in the spiral casing propagate downstream and significantly affect the swirling vortex-rope precession in the draft tube, leading to the changes of the intensity and the processional frequency of the swirling vortex rope. When the guide vane opening approaches the optimum one (representing the full-load condition), the upstream disturbance becomes weaker and thus its influences on the downstream flow are very limited.

Nutrition Coupled with High-Load Traditional or Low-Load Blood Flow Restricted Exercise During Human Limb Suspension

Science.gov (United States)

Hackney, K. J.; Everett, M.; Ploutz-Snyder, L. L.

2011-01-01

High-load resistance exercise (HRE) and low-load blood flow restricted (BFR) exercise have demonstrated efficacy for attenuating unloading related muscle atrophy and dysfunction. In recreational exercisers, protein consumption immediately before and/or after exercise has been shown to increase the skeletal muscle anabolic response to resistance training. PURPOSE: To compare the skeletal muscle adaptations when chocolate milk intake was coupled with HRE or low-load BFR exercise [3 d/wk] during simulated lower limb weightlessness. METHODS: Eleven subjects were counterbalanced [based on age and gender] to HRE (31 +/- 14 yr, 170 +/- 13 cm, 71 +/- 18 kg, 2M/3W) or low-load BFR exercise (31 +/- 12 yr, 169 +/- 13 cm, 66 +/- 14 kg, 2M/4W) during 30 days of unilateral lower limb suspension (ULLS). Both HRE and BFR completed 3 sets of single leg press and calf raise exercise during ULLS. BFR exercise intensity was 20% of repetition maximum (1RM) with a cuff inflation pressure of 1.3 systolic blood pressure (143 4 mmHg). Cuff pressure was maintained during all 3 sets including rest intervals (90s). HRE intensity was 75% 1RM and was performed without cuff inflation. Immediately (HRE vs. BFR, respectively. Leg press training loads were 44 +/- 7 kg in HRE compared to 11 +/- 1 kg in BFR. Similarly, calf raise training loads were 81 +/- 11 kg in HRE and 16 +/- 1 kg in BFR. Pre to post-ULLS training adaptations in the unloaded leg are shown in the table. CONCLUSION: The preliminary results of this investigation suggest when HRE is optimized for muscle anabolism during unloading muscle size and strength are preserved (or enhanced) at the expense of muscle endurance. In contrast, when BFR exercise is optimized for muscle anabolism during unloading muscle endurance is preserved (or enhanced) at the expense of muscle size and strength

The cryogenic cooling program in high-heat-load optics at the Advanced Photon Source

International Nuclear Information System (INIS)

Rogers, C.S.

1993-07-01

This paper describes some of the aspects of the cryogenic optics program at the Advanced Photon Source (APS). A liquid-nitrogen-cooled, high-vacuum, double crystal monochromator is being fabricated at Argonne National Laboratory (ANL). A pumping system capable of delivering a variable flow rate of up to 10 gallons per minute of pressurized liquid nitrogen and removing 5 kilowatts of x-ray power is also being constructed. This specialized pumping system and monochromator will be used to test the viability of cryogenically cooled, high-heat-load synchrotron optics. It has been determined that heat transfer enhancement will be required for optics used with APS insertion devices. An analysis of a porous-matrix-enhanced monochromator crystal is presented. For the particular case investigated, a heat transfer enhancement factor of 5 to 6 was calculated

COMPARATIVE STUDY OF THREE LINEAR SYSTEM SOLVER APPLIED TO FAST DECOUPLED LOAD FLOW METHOD FOR CONTINGENCY ANALYSIS

Directory of Open Access Journals (Sweden)

Syafii

2017-03-01

Full Text Available This paper presents the assessment of fast decoupled load flow computation using three linear system solver scheme. The full matrix version of the fast decoupled load flow based on XB methods used in this study. The numerical investigations are carried out on the small and large test systems. The execution time of small system such as IEEE 14, 30, and 57 are very fast, therefore the computation time can not be compared for these cases. Another cases IEEE 118, 300 and TNB 664 produced significant execution speedup. The superLU factorization sparse matrix solver has best performance and speedup of load flow solution as well as in contigency analysis. The invers full matrix solver can solved only for IEEE 118 bus test system in 3.715 second and for another cases take too long time. However for superLU factorization linear solver can solved all of test system in 7.832 second for a largest of test system. Therefore the superLU factorization linear solver can be a viable alternative applied in contingency analysis.

Deemed Savings Estimates for Legacy Air Conditioning and WaterHeating Direct Load Control Programs in PJM Region

Energy Technology Data Exchange (ETDEWEB)

Goldman, Charles

2007-03-01

During 2005 and 2006, the PJM Interconnection (PJM) Load Analysis Subcommittee (LAS) examined ways to reduce the costs and improve the effectiveness of its existing measurement and verification (M&V) protocols for Direct Load Control (DLC) programs. The current M&V protocol requires that a PURPA-compliant Load Research study be conducted every five years for each Load-Serving Entity (LSE). The current M&V protocol is expensive to implement and administer particularly for mature load control programs, some of which are marginally cost-effective. There was growing evidence that some LSEs were mothballing or dropping their DLC programs in lieu of incurring the expense associated with the M&V. This project had several objectives: (1) examine the potential for developing deemed savings estimates acceptable to PJM for legacy air conditioning and water heating DLC programs, and (2) explore the development of a collaborative, regional, consensus-based approach for conducting monitoring and verification of load reductions for emerging load management technologies for customers that do not have interval metering capability.

Loading capacity of various filters for lithium fire generated aerosols

International Nuclear Information System (INIS)

Jeppson, D.W.; Barreca, J.R.

1980-01-01

The lithium aerosol loading capacity of a prefilter, HEPA filters and a sand and gravel bed filter was determined. The test aerosol was characterized and was generated by burning lithium in an unlimited air atmosphere. Correlation to sodium aerosol loading capacities were made to relate existing data to lithium aerosol loadings under varying conditions. This work is being conducted in support of the fusion reactor safety program. The lithium aerosol was generated by burning lithium pools, up to 45 kgs, in a 340 m 3 low humidity air atmosphere to supply aerosol to recirculating filter test loops. The aerosol was sampled to determine particle size, mass concentrations and chemical species. The dew point and gas concentrations were monitored throughout the tests. Loop inlet aerosol mass concentrations ranged up to 5 gr/m 3 . Chemical compounds analyzed to be present in the aerosol include Li 2 O, LiOH, and Li 2 CO 3 . HEPA filters with and without separators and a prefilter and HEPA filter in series were loaded with 7.8 to 11.1 kg/m 2 of aerosol at a flow rate of 1.31 m/sec and 5 kPa pressure drop. The HEPA filter loading capacity was determined to be greater at a lower flow rate. The loading capacity increased from 0.4 to 2.8 kg by decreasing the flow rate from 1.31 to 0.26 m/sec for a pressure drop of 0.11 kPa due to aerosol buildup. The prefilter tested in series with a HEPA did not increase the total loading capacity significantly for the same total pressure drop. Separators in the HEPA had only minor effect on loading capacity. The sand and gravel bed filter loaded to 0.50 kg/m 2 at an aerosol flow rate of 0.069 m/sec and final pressure drop of 6.2 kPa. These loading capacities and their dependence on test variables are similar to those reported for sodium aerosols except for the lithium aerosol HEPA loading capacity dependence upon flow rate

Interaction of mass-loaded solar wind flow with blunt body

International Nuclear Information System (INIS)

Breus, T.K.; Krymskii, A.M.; Mitnitskii, V.Ya.

1987-01-01

The aim of this paper is the numerical modeling of the solar wind interaction with Venus taking into account the mass loading effect due to the photoionization of the Venus neutral oxygen corona. The analysis has shown that this effect unambiguously explains the number of peculiarities of the SW-Venus interaction pattern that could not be quantitatively explained before, namely the shock front position, and the characteristics of the SW flow and magnetic field in the Venus ionosheath observed from experiments onboard of Venera-9 and -10 and Pioneer-Venus spacecraft. (author)

Characterization of the wind loads and flow fields around a gable-roof building model in tornado-like winds

Energy Technology Data Exchange (ETDEWEB)

Hu, Hui; Yang, Zifeng; Sarkar, Partha [Iowa State University, Department of Aerospace Engineering, Ames, IA (United States); Haan, Fred [Iowa State University, Department of Aerospace Engineering, Ames, IA (United States); Rose-Hulman Institute of Technology, Department of Mechanical Engineering, Terre Haute, IN (United States)

2011-09-15

An experimental study was conducted to quantify the characteristics of a tornado-like vortex and to reveal the dynamics of the flow-structure interactions between a low-rise, gable-roof building model and swirling, turbulent tornado-like winds. The experimental work was conducted by using a large-scale tornado simulator located in the Aerospace Engineering Department of Iowa State University. In addition to measuring the pressure distributions and resultant wind loads acting on the building model, a digital Particle Image Velocimetry system was used to conduct detailed flow field measurements to quantify the evolution of the unsteady vortices and turbulent flow structures around the gable-roof building model in tornado-like winds. The effects of important parameters, such as the distance between the centers of the tornado-like vortex and the test model and the orientation angles of the building model related to the tornado-like vortex, on the evolutions of the wake vortices and turbulent flow structures around the gable-roof building model as well as the wind loads induced by the tornado-like vortex were assessed quantitatively. The detailed flow field measurements were correlated with the surface pressure and wind load measurements to elucidate the underlying physics to gain further insight into flow-structure interactions between the gable-roof building model and tornado-like winds in order to provide more accurate prediction of wind damage potential to built structures. (orig.)

Letter to the Editor: Electric Vehicle Demand Model for Load Flow Studies

DEFF Research Database (Denmark)

Garcia-Valle, Rodrigo; Vlachogiannis, Ioannis (John)

2009-01-01

This paper introduces specific and simple model for electric vehicles suitable for load flow studies. The electric vehicles demand system is modelled as PQ bus with stochastic characteristics based on the concept of queuing theory. All appropriate variables of stochastic PQ buses are given...... with closed formulae as a function of charging time. Specific manufacturer model of electric vehicles is used as study case....

Experimental evaluation of ability of Relap5, Drako, Flowmaster2TM and program using unsteady wall friction model to calculate water hammer loadings on pipelines

International Nuclear Information System (INIS)

Marcinkiewicz, Jerzy; Adamowski, Adam; Lewandowski, Mariusz

2008-01-01

Mechanical loadings on pipe systems caused by water hammer (hydraulic transients) belong to the most important and most difficult to calculate design loadings in nuclear power plants. The most common procedure in Sweden is to calculate the water hammer loadings on pipe segments, according to the classical one-dimensional (1D) theory of liquid transient flow in a pipeline, and then transfer the results to strength analyses of pipeline structure. This procedure assumes that there is quasi-steady respond of the pipeline structure to pressure surges-no dynamic interaction between the fluid and the pipeline construction. The hydraulic loadings are calculated with 1D so-called 'network' programs. Commonly used in Sweden are Relap5, Drako and Flowmaster2-all using quasi-steady wall friction model. As a third party accredited inspection body Inspecta Nuclear AB reviews calculations of water hammer loadings. The presented work shall be seen as an attempt to illustrate ability of Relap5, Flowmaster2 and Drako programs to calculate the water hammer loadings. A special attention was paid to using of Relap5 for calculation of water hammer pressure surges and forces (including some aspects of influence of Courant number on the calculation results) and also the importance of considering the dynamic (or unsteady) friction models. The calculations are compared with experimental results. The experiments have been conducted at a test rig designed and constructed at the Szewalski Institute of Fluid Flow Machinery of the Polish Academy of Sciences (IMP PAN) in Gdansk, Poland. The analyses show quite small differences between pressures and forces calculated with Relap5, Flowmaster2 and Drako (the differences regard mainly damping of pressure waves). The comparison of calculated and measured pressures and also a force acting on a pre-defined pipe segment shows significant differences. It is shown that the differences can be reduced by using unsteady friction models in calculations

PACTOLUS, Nuclear Power Plant Cost and Economics by Discounted Cash Flow Method. CLOTHO, Mass Flow Data Calculation for Program PACTOLUS

International Nuclear Information System (INIS)

Haffner, D.R.

1976-01-01

1 - Description of problem or function: PACTOLUS is a code for computing nuclear power costs using the discounted cash flow method. The cash flows are generated from input unit costs, time schedules and burnup data. CLOTHO calculates and communicates to PACTOLUS mass flow data to match a specified load factor history. 2 - Method of solution: Plant lifetime power costs are calculated using the discounted cash flow method. 3 - Restrictions on the complexity of the problem - Maxima of: 40 annual time periods into which all costs and mass flows are accumulated, 20 isotopic mass flows charged into and discharged from the reactor model

Load leveling total system. Part 2. Development of load leveling logic for residential customer; Fuka heijunka total system. 2. Kateiyo juyoka wo taisho to shita heijunka ronri no kaihatsu

Energy Technology Data Exchange (ETDEWEB)

Asari, M.; Nanahara, T. [Central Research Institute of Electric Power Industry, Tokyo (Japan)

1995-05-01

It is essential, in order to meet steadily increasing demands for electrical power, to develop techniques for effective utilization of energy and load leveling. Described herein is development, by the aid of linear programming, of logic for daily management of charge/discharge of load conditioners and reverse power flow, for predicted loads and patterns of power generated by photovoltaic cells installed at individual customers. It is aimed at minimizing power rate and leveling of load at distribution systems. Predicted loads, outputs by photovoltaic cell units and different power rates by time zone for the next day are inputted, to determine the charge/discharge schedules and power supply/reverse flow patterns for that day, in order to minimize power rates and level loads at higher hierarchical levels. The logic-aided daily simulation for various districts confirms the operational patterns that realize improved utilization of pole-mounted transformers while reducing costs at customers, and effects of prediction errors. 4 refs., 14 figs.

Flow time analysis of load management late arrival discrete time queueing system with dual service rate using hypo geometrical distribution

International Nuclear Information System (INIS)

Shah, S.A.; Shah, W.; Shaikh, F.K.

2012-01-01

Flow time analysis is a powerful concept to analyze the flow time of any arriving customer in any system at any instant. A load management mechanism can be employed very effectively in any queueing system by utilizing a system which provides probability of dual service rate. In this paper, we develop and demonstrate the flow and service processes transition diagram to determine the flow time of a customer in a load management late arrival state dependent finite discrete time queueing system with dual service rate where customers are hypo geometrically distributed. We compute the probability mass function of each starting state and total probability mass function. The obtained analytical results are validated with simulation results for varying values of arrival and service probabilities. (author)

Towards Separation of Concerns in Flow-Based Programming

DEFF Research Database (Denmark)

Zarrin, Bahram; Baumeister, Hubert

2015-01-01

Flow-Based Programming (FBP) is a programming paradigm that models software systems as a directed graph of predefined processes which run asynchronously and exchange data through input and output ports. FBP decomposes software systems into a network of processes. However there are concerns...

Nested-scale discharge and groundwater level monitoring to improve predictions of flow route discharges and nitrate loads

Science.gov (United States)

van der Velde, Y.; Rozemeijer, J. C.; de Rooij, G. H.; van Geer, F. C.; Torfs, P. J. J. F.; de Louw, P. G. B.

2010-10-01

Identifying effective measures to reduce nutrient loads of headwaters in lowland catchments requires a thorough understanding of flow routes of water and nutrients. In this paper we assess the value of nested-scale discharge and groundwater level measurements for predictions of catchment-scale discharge and nitrate loads. In order to relate field-site measurements to the catchment-scale an upscaling approach is introduced that assumes that scale differences in flow route fluxes originate from differences in the relationship between groundwater storage and the spatial structure of the groundwater table. This relationship is characterized by the Groundwater Depth Distribution (GDD) curve that relates spatial variation in groundwater depths to the average groundwater depth. The GDD-curve was measured for a single field site (0.009 km2) and simple process descriptions were applied to relate the groundwater levels to flow route discharges. This parsimonious model could accurately describe observed storage, tube drain discharge, overland flow and groundwater flow simultaneously with Nash-Sutcliff coefficients exceeding 0.8. A probabilistic Monte Carlo approach was applied to upscale field-site measurements to catchment scales by inferring scale-specific GDD-curves from hydrographs of two nested catchments (0.4 and 6.5 km2). The estimated contribution of tube drain effluent (a dominant source for nitrates) decreased with increasing scale from 76-79% at the field-site to 34-61% and 25-50% for both catchment scales. These results were validated by demonstrating that a model conditioned on nested-scale measurements simulates better nitrate loads and better predictions of extreme discharges during validation periods compared to a model that was conditioned on catchment discharge only.

Planning Student Flow with Linear Programming: A Tunisian Case Study.

Science.gov (United States)

Bezeau, Lawrence

A student flow model in linear programming format, designed to plan the movement of students into secondary and university programs in Tunisia, is described. The purpose of the plan is to determine a sufficient number of graduating students that would flow back into the system as teachers or move into the labor market to meet fixed manpower…

Automated system for load flow prediction in power substations using artificial neural networks

Directory of Open Access Journals (Sweden)

Arlys Michel Lastre Aleaga

2015-09-01

Full Text Available The load flow is of great importance in assisting the process of decision making and planning of generation, distribution and transmission of electricity. Ignorance of the values in this indicator, as well as their inappropriate prediction, difficult decision making and efficiency of the electricity service, and can cause undesirable situations such as; the on demand, overheating of the components that make up a substation, and incorrect planning processes electricity generation and distribution. Given the need for prediction of flow of electric charge of the substations in Ecuador this research proposes the concept for the development of an automated prediction system employing the use of Artificial Neural Networks.

Modeling the Design Flow Coefficient of a Centrifugal Compressor Impeller

Directory of Open Access Journals (Sweden)

A. A. Drozdov

2017-01-01

Full Text Available In calculating gas-dynamic characteristics by the universal modeling method it is necessary to determine a non-incidence flow rate through the blades of an impeller because of its relationship with the magnitude of incidence losses. The flow area decreased by the blades of finite thickness and the blades load have impact on the critical streamline direction. The universal modeling method in primary designing uses for this a scheme of replacing the influence of the blade load by the vortex effect with identical circulation. Finally, calculating the inviscid flow around the blades allows selecting a value of the inlet blade angle. For impellers with small design flow coefficients, the condition of the non-incidence inlet for the primary design and for the calculation of the inviscid flow is significantly different. The calculating correctness of the non-incidence regime for the non-viscous flow was checked earlier by measurements of the flow in the impellers. The paper presents CFD calculations of twenty impellers in a tenfold range of design flow coefficients. To provide correct comparison, it takes into account the differences in the value of the loading factor calculated by the programs of inviscid quasi-three-dimensional calculation and CFD programs. Shows the identity of inlet conditions for both methods. To increase primary design accuracy, the calculation model was refined. The formula for calculating vortex-induced velocity involves an empirical coefficient. The analysis of data for 32 impellers with different blade profiling allowed working out formulas for calculating empirical coefficient, depending on the type of an impeller, the blade load and the width of the throat at an impeller inlet. The new scheme-based calculation with the empirical coefficient is accurate enough for the primary design.

Voltage profile program for the Kennedy Space Center electric power distribution system

Science.gov (United States)

1976-01-01

The Kennedy Space Center voltage profile program computes voltages at all busses greater than 1 Kv in the network under various conditions of load. The computation is based upon power flow principles and utilizes a Newton-Raphson iterative load flow algorithm. Power flow conditions throughout the network are also provided. The computer program is designed for both steady state and transient operation. In the steady state mode, automatic tap changing of primary distribution transformers is incorporated. Under transient conditions, such as motor starts etc., it is assumed that tap changing is not accomplished so that transformer secondary voltage is allowed to sag.

Market-oriented programming and its application to power load management

Energy Technology Data Exchange (ETDEWEB)

Ygge, F

1998-04-01

Market-oriented programming is a new approach to design and implementation of resource allocation mechanisms in computer systems. It has its roots in different disciplines, such as economics and computer science (in particular the area of multi-agent systems). This is divided into two different parts, focusing on: (1) central foundations and mechanisms of market-oriented programming, and (2) the use of market-oriented programming in practical applications. Market-oriented programming is seen as a programming paradigm based on abstractions such as prices and demands. Concepts, terminology and theory from micro-economics form the foundations of the paradigm. Central aspects of these foundations are investigated and some new insights are presented. Furthermore, some relations between standard optimization/resource allocation approaches and markets are described, and novel theorems are introduced. A published, and generally recognized, market oriented approach to the application building climate control is analyzed in detail. A new approach to this application, based on market-oriented programming, is introduced and shown to be superior to the analyzed approach in many ways. The case study pinpoints a number of potential pitfalls as well as advantages of market-oriented approaches to this and other applications. A second investigated application is power load management, i.e. the management of loads at the customer`s side for obtaining more efficient energy systems management. The basis of the application is described and a new market oriented approach is introduced and analyzed. The approach is shown to have a number of advantages compared to existing approaches to this problem. The main conclusion of the thesis is that there are some potential pitfalls of market-oriented programming, but when used with care it provides a highly natural and efficient means for resource allocation in computer systems

Flow Induced Vibration Program at Argonne National Laboratory

International Nuclear Information System (INIS)

1984-01-01

Argonne National Laboratory has had a Flow Induced Vibration Program since 1967; the Program currently resides in the Laboratory's Components Technology Division. Throughout its existence, the overall objective of the program has been to develop and apply new and/or improved methods of analysis and testing for the design evaluation of nuclear reactor plant components and heat exchange equipment from the standpoint of flow induced vibration. Historically, the majority of the program activities have been funded by the US Atomic Energy Commission (AEC), Energy Research and Development Administration (ERDA), and Department of Energy (DOE). Current DOE funding is from the Breeder Mechanical Component Development Division, Office of Breeder Technology Projects; Energy Conversion and Utilization Technology (ECUT) Program, Office of Energy Systems Research; and Division of Engineering, Mathematical and Geosciences, Office of Basic Energy Sciences. Testing of Clinch River Breeder Reactor upper plenum components has been funded by the Clinch River Breeder Reactor Plant (CRBRP) Project Office. Work has also been performed under contract with Foster Wheeler, General Electric, Duke Power Company, US Nuclear Regulatory Commission, and Westinghouse

Different elution modes and field programming in gravitational field-flow fractionation. III. Field programming by flow-rate gradient generated by a programmable pump.

Science.gov (United States)

Plocková, J; Chmelík, J

2001-05-25

Gravitational field-flow fractionation (GFFF) utilizes the Earth's gravitational field as an external force that causes the settlement of particles towards the channel accumulation wall. Hydrodynamic lift forces oppose this action by elevating particles away from the channel accumulation wall. These two counteracting forces enable modulation of the resulting force field acting on particles in GFFF. In this work, force-field programming based on modulating the magnitude of hydrodynamic lift forces was implemented via changes of flow-rate, which was accomplished by a programmable pump. Several flow-rate gradients (step gradients, linear gradients, parabolic, and combined gradients) were tested and evaluated as tools for optimization of the separation of a silica gel particle mixture. The influence of increasing amount of sample injected on the peak resolution under flow-rate gradient conditions was also investigated. This is the first time that flow-rate gradients have been implemented for programming of the resulting force field acting on particles in GFFF.

Flow Induced Vibration Program at Argonne National Laboratory

Science.gov (United States)

1984-01-01

The Argonne National Laboratory's Flow Induced Vibration Program, currently residing in the Laboratory's Components Technology Division is discussed. Throughout its existence, the overall objective of the program was to develop and apply new and/or improved methods of analysis and testing for the design evaluation of nuclear reactor plant components and heat exchange equipment from the standpoint of flow induced vibration. Historically, the majority of the program activities were funded by the US Atomic Energy Commission, the Energy Research and Development Administration, and the Department of Energy. Current DOE funding is from the Breeder Mechanical Component Development Division, Office of Breeder Technology Projects; Energy Conversion and Utilization Technology Program, Office of Energy Systems Research; and Division of Engineering, Mathematical and Geosciences, office of Basic Energy Sciences. Testing of Clinch River Breeder Reactor upper plenum components was funded by the Clinch River Breeder Reactor Plant Project Office. Work was also performed under contract with Foster Wheeler, General Electric, Duke Power Company, US Nuclear Regulatory Commission, and Westinghouse.

Interfacing a General Purpose Fluid Network Flow Program with the SINDA/G Thermal Analysis Program

Science.gov (United States)

Schallhorn, Paul; Popok, Daniel

1999-01-01

A general purpose, one dimensional fluid flow code is currently being interfaced with the thermal analysis program Systems Improved Numerical Differencing Analyzer/Gaski (SINDA/G). The flow code, Generalized Fluid System Simulation Program (GFSSP), is capable of analyzing steady state and transient flow in a complex network. The flow code is capable of modeling several physical phenomena including compressibility effects, phase changes, body forces (such as gravity and centrifugal) and mixture thermodynamics for multiple species. The addition of GFSSP to SINDA/G provides a significant improvement in convective heat transfer modeling for SINDA/G. The interface development is conducted in multiple phases. This paper describes the first phase of the interface which allows for steady and quasi-steady (unsteady solid, steady fluid) conjugate heat transfer modeling.

FLOWNET: A Computer Program for Calculating Secondary Flow Conditions in a Network of Turbomachinery

Science.gov (United States)

Rose, J. R.

1978-01-01

The program requires the network parameters, the flow component parameters, the reservoir conditions, and the gas properties as input. It will then calculate all unknown pressures and the mass flow rate in each flow component in the network. The program can treat networks containing up to fifty flow components and twenty-five unknown network pressures. The types of flow components that can be treated are face seals, narrow slots, and pipes. The program is written in both structured FORTRAN (SFTRAN) and FORTRAN 4. The program must be run in an interactive (conversational) mode.

Phloem loading in two Scrophulariaceae species. What can drive symplastic flow via plasmodesmata?

Science.gov (United States)

Voitsekhovskaja, Olga V; Koroleva, Olga A; Batashev, Denis R; Knop, Christian; Tomos, A Deri; Gamalei, Yuri V; Heldt, Hans-Walter; Lohaus, Gertrud

2006-01-01

To determine the driving forces for symplastic sugar flux between mesophyll and phloem, gradients of sugar concentrations and osmotic pressure were studied in leaf tissues of two Scrophulariaceae species, Alonsoa meridionalis and Asarina barclaiana. A. meridionalis has a typical symplastic configuration of minor-vein phloem, i.e. intermediary companion cells with highly developed plasmodesmal connections to bundle-sheath cells. In A. barclaiana, two types of companion cells, modified intermediary cells and transfer cells, were found in minor-vein phloem, giving this species the potential to have a complex phloem-loading mode. We identified all phloem-transported carbohydrates in both species and analyzed the levels of carbohydrates in chloroplasts, vacuoles, and cytoplasm of mesophyll cells by nonaqueous fractionation. Osmotic pressure was measured in single epidermal and mesophyll cells and in whole leaves and compared with calculated values for phloem sap. In A. meridionalis, a 2-fold concentration gradient for sucrose between mesophyll and phloem was found. In A. barclaiana, the major transported carbohydrates, sucrose and antirrhinoside, were present in the phloem in 22- and 6-fold higher concentrations, respectively, than in the cytoplasm of mesophyll cells. The data show that diffusion of sugars along their concentration gradients is unlikely to be the major mechanism for symplastic phloem loading if this were to occur in these species. We conclude that in both A. meridionalis and A. barclaiana, apoplastic phloem loading is an indispensable mechanism and that symplastic entrance of solutes into the phloem may occur by mass flow. The conditions favoring symplastic mass flow into the phloem are discussed.

Effects of an intensive weight loss program on knee joint loading in obese adults with knee osteoarthritis

DEFF Research Database (Denmark)

Aaboe, J; Bliddal, H; Messier, S P

2011-01-01

To determine the effect of an intensive weight loss program on knee joint loads during walking in obese patients with knee osteoarthritis (OA).......To determine the effect of an intensive weight loss program on knee joint loads during walking in obese patients with knee osteoarthritis (OA)....

Foundations of Total Functional Data-Flow Programming

Directory of Open Access Journals (Sweden)

Baltasar Trancón y Widemann

2014-06-01

Full Text Available The field of declarative stream programming (discrete time, clocked synchronous, modular, data-centric is divided between the data-flow graph paradigm favored by domain experts, and the functional reactive paradigm favored by academics. In this paper, we describe the foundations of a framework for unifying functional and data-flow styles that differs from FRP proper in significant ways: It is based on set theory to match the expectations of domain experts, and the two paradigms are reduced symmetrically to a low-level middle ground, with strongly compositional semantics. The design of the framework is derived from mathematical first principles, in particular coalgebraic coinduction and a standard relational model of stateful computation. The abstract syntax and semantics introduced here constitute the full core of a novel stream programming language.

The FAA/NASA flight loads monitoring program - The prototype system and its benefits for the aviation community

Science.gov (United States)

Whitehead, Julia H.; Thomas, Mitchel E.; Carrelli, David J.; Crabill, Norman L.

1992-01-01

The FAA established the flight load monitoring program to collect a data base of typical flight operational loads experienced by commercial transports. This system will provide a comprehensive monitoring of aircraft loading conditions with over 20 flight parameters being recorded simultaneously. NASA is designing and testing a prototype data collection and analysis system which will be implemented into an FAA operational program. This paper presents the program's objectives and the proposed development testing on a commercial Boeing 737-400. The prototype system, its data processing schemes, and reports are described. The searching criteria or flight attributes generated for each flight are listed. The data processing system will provide the aviation community with a powerful tool for the study of transport flight loading conditions and the system's flexibility will accommodate individual studies and specialized concerns.

Technical Potential for Peak Load Management Programs in New Jersey

Energy Technology Data Exchange (ETDEWEB)

Kirby, B.J.

2002-12-13

producers and consumers. Fortunately too, only a percentage of loads need to respond elastically for all customers to benefit. This report explores mechanisms to reduce, when necessary, the peak load in New Jersey's electricity market. It examines load pricing and technical load reduction programs used in recent years in New Jersey and discuss how they can be made more effective in controlling summer peaks and attendant high prices of electricity. Particular attention is given to load curtailment programs now in place and utility opinions relating to them.

Approximate solution of oil film load-carrying capacity of turbulent journal bearing with couple stress flow

Science.gov (United States)

Zhang, Yongfang; Wu, Peng; Guo, Bo; Lü, Yanjun; Liu, Fuxi; Yu, Yingtian

2015-01-01

The instability of the rotor dynamic system supported by oil journal bearing is encountered frequently, such as the half-speed whirl of the rotor, which is caused by oil film lubricant with nonlinearity. Currently, more attention is paid to the physical characteristics of oil film due to an oil-lubricated journal bearing being the important supporting component of the bearing-rotor systems and its nonlinear nature. In order to analyze the lubrication characteristics of journal bearings efficiently and save computational efforts, an approximate solution of nonlinear oil film forces of a finite length turbulent journal bearing with couple stress flow is proposed based on Sommerfeld and Ocvirk numbers. Reynolds equation in lubrication of a finite length turbulent journal bearing is solved based on multi-parametric principle. Load-carrying capacity of nonlinear oil film is obtained, and the results obtained by different methods are compared. The validation of the proposed method is verified, meanwhile, the relationships of load-carrying capacity versus eccentricity ratio and width-to-diameter ratio under turbulent and couple stress working conditions are analyzed. The numerical results show that both couple stress flow and eccentricity ratio have obvious influence on oil film pressure distribution, and the proposed method approximates the load-carrying capacity of turbulent journal bearings efficiently with various width-to-diameter ratios. This research proposes an approximate solution of oil film load-carrying capacity of turbulent journal bearings with different width-to-diameter ratios, which are suitable for high eccentricity ratios and heavy loads.

Blood flow in skin, subcutaneous adipose tissue and skeletal muscle in the forearm of normal man during an oral glucose load

DEFF Research Database (Denmark)

Bülow, J; Astrup, A; Christensen, N J

1987-01-01

Blood flow to the forearm, and the subcutaneous tissue and skin in the forearm were measured by strain gauge plethysmography, 133Xe-elimination and Laser Doppler flowmetry during an oral glucose load (I g glucose kg-1 lean body mass) and during control conditions. The forearm blood flow remained...... constant during both experiments. Glucose induced a two-fold vasodilatation in subcutaneous tissue. In skin, glucose induced a relative vasodilatation and later a relative vasoconstriction compared with control experiments. When estimated from forearm blood flow and subcutaneous and skin blood flows......, muscle blood flow decreased about 20-30% during both experiments. Proximal nervous blockade did not abolish the glucose-induced vasodilatation in subcutaneous tissue. In the glucose experiment, arterial glucose concentration increased to 7.8 +/- 1.17 mmol l-1 30 min after the load was given...

Provably Correct Control-Flow Graphs from Java Programs with Exceptions

NARCIS (Netherlands)

Amighi, A.; de Carvalho Gomes, Pedro; Huisman, Marieke

2011-01-01

We present an algorithm to extract flow graphs from Java bytecode, focusing on exceptional control flows. We prove its correctness, meaning that the behaviour of the extracted control-flow graph is an over-approximation of the behaviour of the original program. Thus any safety property that holds

Load research manual. Volume 1. Load research procedures

Energy Technology Data Exchange (ETDEWEB)

Brandenburg, L.; Clarkson, G.; Grund, Jr., C.; Leo, J.; Asbury, J.; Brandon-Brown, F.; Derderian, H.; Mueller, R.; Swaroop, R.

1980-11-01

This three-volume manual presents technical guidelines for electric utility load research. Special attention is given to issues raised by the load data reporting requirements of the Public Utility Regulatory Policies Act of 1978 and to problems faced by smaller utilities that are initiating load research programs. In Volumes 1 and 2, procedures are suggested for determining data requirements for load research, establishing the size and customer composition of a load survey sample, selecting and using equipment to record customer electricity usage, processing data tapes from the recording equipment, and analyzing the data. Statistical techniques used in customer sampling are discussed in detail. The costs of load research also are estimated, and ongoing load research programs at three utilities are described. The manual includes guides to load research literature and glossaries of load research and statistical terms.

Computing Programs for Determining Traffic Flows from Roundabouts

Science.gov (United States)

Boroiu, A. A.; Tabacu, I.; Ene, A.; Neagu, E.; Boroiu, A.

2017-10-01

For modelling road traffic at the level of a road network it is necessary to specify the flows of all traffic currents at each intersection. These data can be obtained by direct measurements at the traffic light intersections, but in the case of a roundabout this is not possible directly and the literature as well as the traffic modelling software doesn’t offer ways to solve this issue. Two sets of formulas are proposed by which all traffic flows from the roundabouts with 3 or 4 arms are calculated based on the streams that can be measured. The objective of this paper is to develop computational programs to operate with these formulas. For each of the two sets of analytical relations, a computational program was developed in the Java operating language. The obtained results fully confirm the applicability of the calculation programs. The final stage for capitalizing these programs will be to make them web pages in HTML format, so that they can be accessed and used on the Internet. The achievements presented in this paper are an important step to provide a necessary tool for traffic modelling because these computational programs can be easily integrated into specialized software.

Programming heterogeneous MPSoCs tool flows to close the software productivity gap

CERN Document Server

Castrillón Mazo, Jerónimo

2014-01-01

This book provides embedded software developers with techniques for programmingheterogeneous Multi-Processor Systems-on-Chip (MPSoCs), capable of executing multiple applications simultaneously. It describes a set of algorithms and methodologies to narrow the software productivity gap, as well as an in-depth description of the underlying problems and challenges of today’s programming practices. The authors present four different tool flows: A parallelism extraction flow for applications writtenusing the C programming language, a mapping and scheduling flow for parallel applications, a special mapping flow for baseband applications in the context of Software Defined Radio (SDR) and a final flow for analyzing multiple applications at design time. The tool flows are evaluated on Virtual Platforms (VPs), which mimic different characteristics of state-of-the-art heterogeneous MPSoCs.   • Provides a novel set of algorithms and methodologies for programming heterogeneous Multi-Processor Systems-on-Chip (MPSoCs)...

Program Computes Flows Of Fluids And Heat

Science.gov (United States)

Cullimore, Brent; Ring, Steven; Welch, Mark

1993-01-01

SINDA'85/FLUINT incorporates lumped-parameter-network and one-dimensional-flow mathematical models. System enables analysis of mutual influences of thermal and flow phenomena. Offers two finite-difference numerical solution techniques: forward-difference explicit approximation and Crank-Nicholson approximation. Enables simulation of nonuniform heating and facilitates mathematical modeling of thin-walled heat exchangers. Ability to model nonequilibrium behavior within two-phase volumes included. Recent changes in program improve modeling of real evaporator pumps and other capillary-assist evaporators. Written in FORTRAN 77.

Probability-based load combinations for design of category I structures - overview of research program and recent results

International Nuclear Information System (INIS)

Reich, M.; Hwang, H.

1984-01-01

This paper discusses the probability-based load combinations for the program dealing with the design of Category I structures, currently being worked on at Brookhaven National Laboratory (BNL) for the Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission (NRC). The objective of this program is to develop a probabilistic approach for the safety evaluations of reactor containments and other seismic Category I structures subjected to multiple static and dynamic loadings. Furthermore, on the basis of the developed probabilistic approach, a load combination methodology for the design of seismic Category I structures will also be established. The major tasks of this program are: (1) establish probabilistic representations for various loads and structural resistance, (2) select appropriate structural analysis methods and identify limit states of structures, (3) develop a reliability analysis method applicable to nuclear structures, (4) apply the developed methodology to existing Category I structures in order to evaluate the reliability levels implied in the current design criteria, and (5) recommend load combination design criteria for Category I structures. When the program is completed, it will be possible to (1) provide a method that can evaluate the safety margins of existing containment and other Category I structures and (2) recommended probability-based load combinations and load factors for the design of Category I structures. At the present time, a reliability analysis method for seismic Category I concrete structures has been completed. By utilizing this method, it is possible to evaluate the safety of structures under various static and dynamic loads. In this paper, results of a reliability analysis of a realistic reinforced concrete containment structure under dead load, accidental pressure, and earthquake ground acceleration are presented to demonstrate the feasibility of the methodology. (orig.)

Patterns of deformation and volcanic flows associated with lithospheric loading by large volcanoes on Venus

Science.gov (United States)

Mcgovern, Patrick J.; Solomon, Sean C.

1993-01-01

Magellan radar imaging and topography data are now available for a number of volcanoes on Venus greater than 100 km in radius. These data can be examined to reveal evidence of the flexural response of the lithosphere to the volcanic load. On Venus, erosion and sediment deposition are negligible, so tectonic evidence of deformation around large volcanoes should be evident except where buried by very young flows. Radar images reveal that most tectonic features and flow units on the flanks of these volcanoes have predominantly radial orientations. However, both Tepev Mons in Bell Regio and Sapas Mons in Atla Regio exhibit circumferential graben on their flanks. In addition, images reveal several flow units with an annular character around the north and west flanks of Tepev Mons. This pattern most likely results from ponding of flows in an annular flexural moat. Maat Mons in Atla Regio and Sif Mons in Eistla Regio are examples of volcanoes that lack circumferential graben and annular flows; discernible flow units and fractures on these constructs appear to be predominantly radial. Altimetry data can also provide evidence of flexural response. Tepev Mons is partially encircled by depressions that may be sections of a flexural moat that has not been completely filled. The locations of these depressions generally coincide with the annular flows described above. There is weaker evidence for such depressions around Maat Mons as well. The lack of circumferential tectonic features around most volcanoes on Venus might be explained by gradual moat filling and coverage by radial flows. The depressions around Tepev (and possible Maat) may indicate that this process is currently continuing. We use analytic models of plate flexure in an axisymmetric geometry to constrain the elastic plate thickness supporting Tepev Mons. If we consider the outer radius of the ponded flows to be the edge of a moat, we find that models with elastic plate thickness of 10-20 km fit best. Finite element

Energy consumption program: A computer model simulating energy loads in buildings

Science.gov (United States)

Stoller, F. W.; Lansing, F. L.; Chai, V. W.; Higgins, S.

1978-01-01

The JPL energy consumption computer program developed as a useful tool in the on-going building modification studies in the DSN energy conservation project is described. The program simulates building heating and cooling loads and computes thermal and electric energy consumption and cost. The accuracy of computations are not sacrificed, however, since the results lie within + or - 10 percent margin compared to those read from energy meters. The program is carefully structured to reduce both user's time and running cost by asking minimum information from the user and reducing many internal time-consuming computational loops. Many unique features were added to handle two-level electronics control rooms not found in any other program.

Field research program for unsaturated flow and transport experimentation

International Nuclear Information System (INIS)

Tidwell, V.C.; Rautman, C.A.; Glass, R.J.

1992-01-01

As part of the Yucca Mountain Site Characterization Project, a field research program has been developed to refine and validate models for flow and transport through unsaturated fractured rock. Validation of these models within the range of their application for performance assessment requires a more sophisticated understanding of the processes that govern flow and transport within fractured porous media than currently exists. In particular, our research is prioritized according to understanding and modeling processes that, if not accurately incorporated into performance assessment models, would adversely impact the project's ability to evaluate repository performance. For this reason, we have oriented our field program toward enhancing our understanding of scaling processes as they relate to effective media property modeling, as well as to the conceptual modeling of complex flow and transport phenomena

Control of the flow rate in decreasing of the water load of peat production

International Nuclear Information System (INIS)

Anon.

1995-01-01

The retention capacity and control of the flow rate was studied in the Aqua-Peat research. The sedimentation ability of solid matter (peat particles), erosion, migration of the solid matter, and the functioning of the retention pipes located in the strip ditches and the sedimentation basins were measured in the research. Detection was also supplemented by laboratory scale models and by measurements made using them. A model, describing the solid matter erosion and migration on the mire, was compiled on the basis of the results. Migration of the solid matter is possible to reduce by pounding the water into the ditching. So there is more time for particles to settle before migration into watercources. By this method it is possible to reduce the solid matter loads caused by heavy rains and power-flows even by 88 %. If the flow control system is equipped with retainers and settling basins, the solid matter retention capacity can rise up to 93-97 %. The results have shown that the retention pipe retainers play more important role in reduction of solid matter load than sedimentation basins. A follow-up study was made using several types of retainers. A 5 cm thick siphon pipe appeared to be the best. The final selection of the retention pipes has, however, to be made as a compromise between the functioning of the drying process, production possibilities and solid matter retention. (1 ref., 2 figs.)

Reusing balanced power flow object components for developing harmonic power flow

Energy Technology Data Exchange (ETDEWEB)

Nadarajah, S. [Peninsular Malaysia Electric Utility Co., Kuala Lumpur (Malaysia). Tenaga Nasional Berhad; Nor, K.M.; Abdel-Akher, M. [Malaysia Univ., Kuala Lumpur (Malaysia). Dept. of Electrical Engineering

2005-07-01

Harmonic power flows are used to examine the effects of nonlinear loads on power systems. In this paper, component technology was re-used for the development of a harmonic power flow. The object-oriented power system model (OO-PSM) was developed separately from a solution algorithm. Nodes, lines, and transformers were modelled as entity objects by classes. Power flow solution algorithms were modelled as control objects and encapsulated inside independent software components within the power system component software architecture (PS-COM). Both the OO-PSM and the PS-COM of the balanced power flow were re-used for developing the proposed harmonic power flow. A no-interaction hypothesis was used to consider both fundamental voltages and nonlinear device data dependence. A direct solution voltage node method was also used. The accuracy of the method was demonstrated using IEEE 14 bus and 30 bus test systems. It was concluded that component technology can be used to develop harmonic power flow programs. 7 refs., 2 tabs., 9 figs.

Analyzing the effect of dynamic loads on economic dispatch in the presence of interline power flow controller using modified BAT algorithm

Directory of Open Access Journals (Sweden)

Y.N. Vijay Kumar

2016-05-01

Full Text Available Now a day, non-uniform increase of demand on a power system turns the research toward the dynamic analysis. In this paper, to perform dynamic analysis and to solve economic load dispatch problem using optimal power flow (OPF, four realistic load levels are considered. Further, the effectiveness of the objective has been enhanced in the presence of interline power flow controller (IPFC. An optimal location identification methodology for IPFC based on line stability index (LSI is also presented. The effect of ramp-rate limits on generations and the effect of dynamic loads on generation fuel cost and transmission losses are also analyzed on standard IEEE-30 bus and real time 23 bus test systems with supporting validations, numerical and graphical results.

Different elution modes and field programming in gravitational field-flow fractionation. III. Field programming by flow-rate gradient generated by a programmable pump

Czech Academy of Sciences Publication Activity Database

Plocková, Jana; Chmelík, Josef

2001-01-01

Roč. 918, č. 2 (2001), s. 361-370 ISSN 0021-9673 R&D Projects: GA AV ČR IAA4031805 Institutional research plan: CEZ:AV0Z4031919 Keywords : field-flow fractionation * field programming * flow-rate gradients Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 2.793, year: 2001

An iterative method for controlling reactive power flow in boundary transformers

Energy Technology Data Exchange (ETDEWEB)

Trigo, Angel L.; Martinez, Jose L.; Riquelme, Jesus; Romero, Esther [Department of Electrical Engineering, University of Seville (Spain)

2011-02-15

This paper presents an operational tool designed to help the system operator to control the reactive power flow in transmission-subtransmission boundary transformers. The main objective is to determine the minimum number of control actions necessary to ensure that reactive power flows in transmission/subtransmission transformers remain within limits. The proposed iterative procedure combines the use of a linear programming problem and a load flow tool. The linear programming assumes a linear behaviour between dependent and control variables around an operating point, modelled with sensitivities. Experimental results regarding IEEE systems are provided comparing the performance of the proposed approach with that of a conventional optimal power flow. (author)

Phloem Loading in Two Scrophulariaceae Species. What Can Drive Symplastic Flow via Plasmodesmata?1

Science.gov (United States)

Voitsekhovskaja, Olga V.; Koroleva, Olga A.; Batashev, Denis R.; Knop, Christian; Tomos, A. Deri; Gamalei, Yuri V.; Heldt, Hans-Walter; Lohaus, Gertrud

2006-01-01

To determine the driving forces for symplastic sugar flux between mesophyll and phloem, gradients of sugar concentrations and osmotic pressure were studied in leaf tissues of two Scrophulariaceae species, Alonsoa meridionalis and Asarina barclaiana. A. meridionalis has a typical symplastic configuration of minor-vein phloem, i.e. intermediary companion cells with highly developed plasmodesmal connections to bundle-sheath cells. In A. barclaiana, two types of companion cells, modified intermediary cells and transfer cells, were found in minor-vein phloem, giving this species the potential to have a complex phloem-loading mode. We identified all phloem-transported carbohydrates in both species and analyzed the levels of carbohydrates in chloroplasts, vacuoles, and cytoplasm of mesophyll cells by nonaqueous fractionation. Osmotic pressure was measured in single epidermal and mesophyll cells and in whole leaves and compared with calculated values for phloem sap. In A. meridionalis, a 2-fold concentration gradient for sucrose between mesophyll and phloem was found. In A. barclaiana, the major transported carbohydrates, sucrose and antirrhinoside, were present in the phloem in 22- and 6-fold higher concentrations, respectively, than in the cytoplasm of mesophyll cells. The data show that diffusion of sugars along their concentration gradients is unlikely to be the major mechanism for symplastic phloem loading if this were to occur in these species. We conclude that in both A. meridionalis and A. barclaiana, apoplastic phloem loading is an indispensable mechanism and that symplastic entrance of solutes into the phloem may occur by mass flow. The conditions favoring symplastic mass flow into the phloem are discussed. PMID:16377750

Hybrid Information Flow Analysis for Programs with Arrays

Directory of Open Access Journals (Sweden)

Gergö Barany

2016-07-01

Full Text Available Information flow analysis checks whether certain pieces of (confidential data may affect the results of computations in unwanted ways and thus leak information. Dynamic information flow analysis adds instrumentation code to the target software to track flows at run time and raise alarms if a flow policy is violated; hybrid analyses combine this with preliminary static analysis. Using a subset of C as the target language, we extend previous work on hybrid information flow analysis that handled pointers to scalars. Our extended formulation handles arrays, pointers to array elements, and pointer arithmetic. Information flow through arrays of pointers is tracked precisely while arrays of non-pointer types are summarized efficiently. A prototype of our approach is implemented using the Frama-C program analysis and transformation framework. Work on a full machine-checked proof of the correctness of our approach using Isabelle/HOL is well underway; we present the existing parts and sketch the rest of the correctness argument.

CAL--ERDA program manual. [Building Design Language; LOADS, SYSTEMS, PLANT, ECONOMICS, REPORT, EXECUTIVE, CAL-ERDA

Energy Technology Data Exchange (ETDEWEB)

Hunn, B. D.; Diamond, S. C.; Bennett, G. A.; Tucker, E. F.; Roschke, M. A.

1977-10-01

A set of computer programs, called Cal-ERDA, is described that is capable of rapid and detailed analysis of energy consumption in buildings. A new user-oriented input language, named the Building Design Language (BDL), has been written to allow simplified manipulation of the many variables used to describe a building and its operation. This manual provides the user with information necessary to understand in detail the Cal-ERDA set of computer programs. The new computer programs described include: an EXECUTIVE Processor to create computer system control commands; a BDL Processor to analyze input instructions, execute computer system control commands, perform assignments and data retrieval, and control the operation of the LOADS, SYSTEMS, PLANT, ECONOMICS, and REPORT programs; a LOADS analysis program that calculates peak (design) zone and hourly loads and the effect of the ambient weather conditions, the internal occupancy, lighting, and equipment within the building, as well as variations in the size, location, orientation, construction, walls, roofs, floors, fenestrations, attachments (awnings, balconies), and shape of a building; a Heating, Ventilating, and Air-Conditioning (HVAC) SYSTEMS analysis program capable of modeling the operation of HVAC components including fans, coils, economizers, humidifiers, etc.; 16 standard configurations and operated according to various temperature and humidity control schedules. A plant equipment program models the operation of boilers, chillers, electrical generation equipment (diesel or turbines), heat storage apparatus (chilled or heated water), and solar heating and/or cooling systems. An ECONOMIC analysis program calculates life-cycle costs. A REPORT program produces tables of user-selected variables and arranges them according to user-specified formats. A set of WEATHER ANALYSIS programs manipulates, summarizes and plots weather data. Libraries of weather data, schedule data, and building data were prepared.

A Power Load Distribution Algorithm to Optimize Data Center Electrical Flow

Directory of Open Access Journals (Sweden)

Paulo Maciel

2013-07-01

Full Text Available Energy consumption is a matter of common concern in the world today. Research demonstrates that as a consequence of the constantly evolving and expanding field of information technology, data centers are now major consumers of electrical energy. Such high electrical energy consumption emphasizes the issues of sustainability and cost. Against this background, the present paper proposes a power load distribution algorithm (PLDA to optimize energy distribution of data center power infrastructures. The PLDA, which is based on the Ford-Fulkerson algorithm, is supported by an environment called ASTRO, capable of performing the integrated evaluation of dependability, cost and sustainability. More specifically, the PLDA optimizes the flow distribution of the energy flow model (EFM. EFMs are responsible for estimating sustainability and cost issues of data center infrastructures without crossing the restrictions of the power capacity that each device can provide (power system or extract (cooling system. Additionally, a case study is presented that analyzed seven data center power architectures. Significant results were observed, achieving a reduction in power consumption of up to 15.5%.

Calculation of piping loads due to filling procedures; Berechnung von Rohrleitungsbelastungen durch Fuellvorgaenge

Energy Technology Data Exchange (ETDEWEB)

Swidersky, Harald; Thiele, Thomas [TUeV Sued Industrie Service GmbH, Muenchen (Germany)

2012-11-01

Filling procedures in piping systems are usually not load cases that are studied by fluid dynamic and structure dynamic analyses with respect to the integrity of pipes and supports. Although, their frequency is higher than that of postulated accidental transients, therefore they have to be considered for fatigue analyses. The piping and support loads due to filling procedures are caused by the density differences if the transported fluids, for instance in flows with the transport of gas bubbles. The impact duration of the momentum forces is defined by the flow velocity and the length of discontinuities in the piping segments. Filling procedures end very often with a shock pressure, caused by the impact and decelerating of the fluid front at smaller cross sections. The suitability of the thermally hydraulics program RELAP/MOD3.3 for the calculation of realistic loads from filling procedures was studied, the results compared with experimental data. It is shown that dependent on the discretization level the loads are partial significantly underestimated.

Effect of load transients on SOFC operation—current reversal on loss of load

Science.gov (United States)

Gemmen, Randall S.; Johnson, Christopher D.

The dynamics of solid oxide fuel cell (SOFC) operation have been considered previously, but mainly through the use of one-dimensional codes applied to co-flow fuel cell systems. In this paper several geometries are considered, including cross-flow, co-flow, and counter-flow. The details of the model are provided, and the model is compared with some initial experimental data. For parameters typical of SOFC operation, a variety of transient cases are investigated, including representative load increase and decrease and system shutdown. Of particular note for large load decrease conditions (e.g., shutdown) is the occurrence of reverse current over significant portions of the cell, starting from the moment of load loss up to the point where equilibrated conditions again provide positive current. Consideration is given as to when such reverse current conditions might most significantly impact the reliability of the cell.

Nested-scale discharge and groundwater level monitoring to improve predictions of flow route discharges and nitrate loads

NARCIS (Netherlands)

Velde, Y. van der; Rozemeijer, J.C.; Rooij, G.H.de; Geer, F.C. van; Torfs, P.J.J.F.; Louw, P.G.B. de

2010-01-01

Identifying effective measures to reduce nutrient loads of headwaters in lowland catchments requires a thorough understanding of flow routes of water and nutrients. In this paper we assess the value of nested-scale discharge and groundwater level measurements for predictions of catchment-scale

BUCLASP 2: A computer program for instability analysis of biaxially loaded composite stiffened panels and other structures

Science.gov (United States)

Tripp, L. L.; Tamekuni, M.; Viswanathan, A. V.

1973-01-01

The use of the computer program BUCLASP2 is described. The program is intended for linear instability analyses of structures such as unidirectionally stiffened panels. Any structure that has a constant cross section in one direction, that may be idealized as an assemblage of beam elements and laminated flat and curved plant strip elements can be analyzed. The loadings considered are combinations of axial compressive loads and in-plane transverse loads. The two parallel ends of the panel must be simply supported and arbitrary elastic boundary conditions may be imposed along any one or both external longitudinal side. This manual consists of instructions for use of the program with sample problems, including input and output information. The theoretical basis of BUCLASP2 and correlations of calculated results with known solutions, are presented.

PIC simulations of conical magnetically insulated transmission line with LTD generator: Transition from self-limited to load-limited flow

Science.gov (United States)

Liu, Laqun; Wang, Huihui; Guo, Fan; Zou, Wenkang; Liu, Dagang

2017-04-01

Based on the 3-dimensional Particle-In-Cell (PIC) code CHIPIC3D, with a new circuit boundary algorithm we developed, a conical magnetically insulated transmission line (MITL) with a 1.0-MV linear transformer driver (LTD) is explored numerically. The values of switch jitter time of LTD are critical parameters for the system, which are difficult to be measured experimentally. In this paper, these values are obtained by comparing the PIC results with experimental data of large diode-gap MITL. By decreasing the diode gap, we find that all PIC results agree well with experimental data only if MITL works on self-limited flow no matter how large the diode gap is. However, when the diode gap decreases to a threshold, the self-limited flow would transfer to a load-limited flow. In this situation, PIC results no longer agree with experimental data anymore due to the anode plasma expansion in the diode load. This disagreement is used to estimate the plasma expansion speed.

Sound Control-Flow Graph Extraction for Java Programs with Exceptions

NARCIS (Netherlands)

Amighi, A.; de Carvalho Gomes, Pedro; Gurov, Dilian; Huisman, Marieke; Eleftherakis, George; Hinchey, Mike; Holcombe, Mike

2012-01-01

We present an algorithm to extract control-flow graphs from Java bytecode, considering exceptional flows. We then establish its correctness: the behavior of the extracted graphs is shown to be a sound over-approximation of the behavior of the original programs. Thus, any temporal safety property

Dimensions of flow during an experiential wilderness science program

Science.gov (United States)

Wang, Robert

Over the past twenty-five years, there has been an alarming decline in academic performance among American students. This trend is seen in failing test scores, poor attendance, and low first-year retention rates at post-secondary institutions. There have been numerous studies that have examined this issue but few to offer solutions. Mihalyi Csikszentmihalyi, the originator of flow theory, suggests that poor academic performance might be best explained in terms of lack of student motivation and engagement (flow) rather than a lack of cognitive abilities. This study was designed to examine a series of activities conducted during an Experiential Wilderness Science Program at a college located in the Rocky Mountain region. Specifically, this study measured student engagement for each activity and described the dimensions (phenomenological, instructional, etc.) that were present when there was a high frequency of engagement among program participants. A combined quantitative and qualitative research methodology was utilized. The Experience Sampling Form (ESF) was administered to 41 freshman students participating in a 3-day wilderness science program to measure the frequency of engagement (flow) for nine different activities. A qualitative investigation using journals, participant interviews, and focus groups was used to describe the dimensions that were present when a high frequency of engagement among program participants was observed. Results revealed that engagement (flow) was highest during two challenge education activities and during a river sampling activity. Dimensions common among these activities included: an environment dimension, a motivation dimension, and an instruction dimension. The environment dimension included: incorporating novel learning activities, creating student interests, and introducing an element of perceived risk. The motivation dimension included: developing internal loci of control, facilitating high levels of self-efficacy, and

Numerical Investigation of the Flow Structure in a Kaplan Draft Tube at Part Load

Science.gov (United States)

Maddahian, R.; Cervantes, M. J.; Sotoudeh, N.

2016-11-01

This research presents numerical simulation of the unsteady flow field inside the draft tube of a Kaplan turbine at part load condition. Due to curvature of streamlines, the ordinary two-equations turbulence models fail to predict the flow features. Therefore, a modification of the Shear Stress Transport (SST-SAS) model is utilized to approximate the turbulent stresses. A guide vane, complete runner and draft tube are considered to insure the real boundary conditions at the draft tube inlet. The outlet boundary is assumed to discharge into the atmosphere. The obtained pressure fluctuations inside the draft tube are in good agreement with available experimental data. In order to further investigate the RVR formation and its movement, the λ2 criterion, relating the position of the vortex core and strength to the second largest Eigen value of the velocity gradient tensor, is employed. The method used for vortex identification shows the flow structure and vortex motion inside the draft tube accurately.

Conceptual plan: Two-Phase Flow Laboratory Program for the Waste Isolation Pilot Plant

International Nuclear Information System (INIS)

Howarth, S.M.

1993-07-01

The Salado Two-Phase Flow Laboratory Program was established to address concerns regarding two-phase flow properties and to provide WIPP-specific, geologically consistent experimental data to develop more appropriate correlations for Salado rock to replace those currently used in Performance Assessment models. Researchers in Sandia's Fluid Flow and Transport Department originally identified and emphasized the need for laboratory measurements of Salado threshold pressure and relative permeability. The program expanded to include the measurement of capillary pressure, rock compressibility, porosity, and intrinsic permeability and the assessment of core damage. Sensitivity analyses identified the anhydrite interbed layers as the most likely path for the dissipation of waste-generated gas from waste-storage rooms because of their relatively high permeability. Due to this the program will initially focus on the anhydrite interbed material. The program may expand to include similar rock and flow measurements on other WIPP materials including impure halite, pure halite, and backfill and seal materials. This conceptual plan presents the scope, objectives, and historical documentation of the development of the Salado Two-Phase Flow Program through January 1993. Potential laboratory techniques for assessing core damage and measuring porosity, rock compressibility, capillary and threshold pressure, permeability as a function of stress, and relative permeability are discussed. Details of actual test designs, test procedures, and data analysis are not included in this report, but will be included in the Salado Two-Phase Flow Laboratory Program Test Plan pending the results of experimental and other scoping activities in FY93

Data-flow Analysis of Programs with Associative Arrays

Directory of Open Access Journals (Sweden)

David Hauzar

2014-05-01

Full Text Available Dynamic programming languages, such as PHP, JavaScript, and Python, provide built-in data structures including associative arrays and objects with similar semantics—object properties can be created at run-time and accessed via arbitrary expressions. While a high level of security and safety of applications written in these languages can be of a particular importance (consider a web application storing sensitive data and providing its functionality worldwide, dynamic data structures pose significant challenges for data-flow analysis making traditional static verification methods both unsound and imprecise. In this paper, we propose a sound and precise approach for value and points-to analysis of programs with associative arrays-like data structures, upon which data-flow analyses can be built. We implemented our approach in a web-application domain—in an analyzer of PHP code.

A stochastic programming approach to manufacturing flow control

OpenAIRE

Haurie, Alain; Moresino, Francesco

2012-01-01

This paper proposes and tests an approximation of the solution of a class of piecewise deterministic control problems, typically used in the modeling of manufacturing flow processes. This approximation uses a stochastic programming approach on a suitably discretized and sampled system. The method proceeds through two stages: (i) the Hamilton-Jacobi-Bellman (HJB) dynamic programming equations for the finite horizon continuous time stochastic control problem are discretized over a set of sample...

An approach to quantify sources, seasonal change, and biogeochemical processes affecting metal loading in streams: Facilitating decisions for remediation of mine drainage

Science.gov (United States)

Kimball, B.A.; Runkel, R.L.; Walton-Day, K.

2010-01-01

Historical mining has left complex problems in catchments throughout the world. Land managers are faced with making cost-effective plans to remediate mine influences. Remediation plans are facilitated by spatial mass-loading profiles that indicate the locations of metal mass-loading, seasonal changes, and the extent of biogeochemical processes. Field-scale experiments during both low- and high-flow conditions and time-series data over diel cycles illustrate how this can be accomplished. A low-flow experiment provided spatially detailed loading profiles to indicate where loading occurred. For example, SO42 - was principally derived from sources upstream from the study reach, but three principal locations also were important for SO42 - loading within the reach. During high-flow conditions, Lagrangian sampling provided data to interpret seasonal changes and indicated locations where snowmelt runoff flushed metals to the stream. Comparison of metal concentrations between the low- and high-flow experiments indicated substantial increases in metal loading at high flow, but little change in metal concentrations, showing that toxicity at the most downstream sampling site was not substantially greater during snowmelt runoff. During high-flow conditions, a detailed temporal sampling at fixed sites indicated that Zn concentration more than doubled during the diel cycle. Monitoring programs must account for diel variation to provide meaningful results. Mass-loading studies during different flow conditions and detailed time-series over diel cycles provide useful scientific support for stream management decisions.

Using wind speed from a blade-mounted flow sensor for power and load assessment on modern wind turbines

Directory of Open Access Journals (Sweden)

M. M. Pedersen

2017-11-01

Full Text Available In this paper an alternative method to evaluate power performance and loads on wind turbines using a blade-mounted flow sensor is investigated. The hypothesis is that the wind speed measured at the blades has a high correlation with the power and loads such that a power or load assessment can be performed from a few hours or days of measurements.In the present study a blade-mounted five-hole pitot tube is used as the flow sensor as an alternative to the conventional approach, where the reference wind speed is either measured at a nearby met mast or on the nacelle using lidar technology or cup anemometers. From the flow sensor measurements, an accurate estimate of the wind speed at the rotor plane can be obtained. This wind speed is disturbed by the presence of the wind turbine, and it is therefore different from the free-flow wind speed. However, the recorded wind speed has a high correlation with the actual power production as well as the flap-wise loads as it is measured close to the blade where the aerodynamic forces are acting.Conventional power curves are based on at least 180 h of 10 min mean values, but using the blade-mounted flow sensor both the observation average time and the overall assessment time can potentially be shortened. The basis for this hypothesis is that the sensor is able to provide more observations with higher accuracy, as the sensor follows the rotation of the rotor and because of the high correlation between the flow at the blades and the power production. This is the research question addressed in this paper.The method is first tested using aeroelastic simulations where the dependence of the radial position and effect of multiple blade-mounted flow sensors are also investigated. Next the method is evaluated on the basis of full-scale measurements on a pitch-regulated, variable-speed 3.6 MW wind turbine.It is concluded that the wind speed derived from the blade-mounted flow sensor is highly correlated with the

A probabilistic calculation of load flow as a method for the evaluation of the impact of stochastic generators and consumers on the network flow; Probabilistische Leistungsflussberechnung als Methode zur Bewertung der Einfluesse stochastischer Erzeuger und Verbraucher auf die Netzbelastung

Energy Technology Data Exchange (ETDEWEB)

Huehnerbein, Benjamin Rudolf

2011-07-01

The load flow situation has significantly changed in electric power systems throughout the deregulation of European electricity market and the development of renewable energy sources. In the past load profiles of transmission lines and transformers were only dependent on the customers power demand. Today it is a mixture of load curves, power feed in by renewables and power transits which affect the usage of the transmission system. This leads to a fluctuating utilisation with a certain probability for each state with respect to the stochastic character of the above influences. Knowledge of the utilisation is the precondition for an efficient dimensioning of the power system. For these specific requirements the probabilistic power flow calculation is introduced and further developed. The state variables of the power system are defined as random variables and the probability of each grid state is determined. Different types of network equations and calculation techniques, resulting from various assumptions and simplifications of the well-known power flow equations are compared. The solution is found by either convolution techniques or Monte-Carlo-Simulation. The mathematic models is completed by implementation of a balanced power generation as well as by the integration of a correlation approach. This allows more or less realistic behavior for the interaction of load and generation on the one hand and the concurrence of similar nodal powers on the other hand. The result is proven by a boundary load flow on the base of the exact load flow equations. This allows a comparison of the minimum and the maximum values between the linearised and the exact solution. As long as this deviation is known, the results of the probabilistic power flow can be used in power system evaluation. At least an approach for the combination of probabilistic power flow and reliability evaluation is outlined to determine the probability for overloading components for the reason of network

Load research manual. Volume 2. Fundamentals of implementing load research procedures

Energy Technology Data Exchange (ETDEWEB)

Brandenburg, L.; Clarkson, G.; Grund, Jr., C.; Leo, J.; Asbury, J.; Brandon-Brown, F.; Derderian, H.; Mueller, R.; Swaroop, R.

1980-11-01

This three-volume manual presents technical guidelines for electric utility load research. Special attention is given to issues raised by the load data reporting requirements of the Public Utility Regulatory Policies Act of 1978 and to problems faced by smaller utilities that are initiating load research programs. In Volumes 1 and 2, procedures are suggested for determining data requirements for load research, establishing the size and customer composition of a load survey sample, selecting and using equipment to record customer electricity usage, processing data tapes from the recording equipment, and analyzing the data. Statistical techniques used in customer sampling are discussed in detail. The costs of load research also are estimated, and ongoing load research programs at three utilities are described. The manual includes guides to load research literature and glossaries of load research and statistical terms.

Non-linear hydrotectonic phenomena: Part I - fluid flow in open fractures under dynamical stress loading

International Nuclear Information System (INIS)

Archambeau, C.B.

1994-01-01

A fractured solid under stress loading (or unloading) can be viewed as behaving macroscopically as a medium with internal, hidden, degrees of freedom, wherein changes in fracture geometry (i.e. opening, closing and extension) and flow of fluid and gas within fractures will produce major changes in stresses and strains within the solid. Likewise, the flow process within fractures will be strongly coupled to deformation within the solid through boundary conditions on the fracture surfaces. The effects in the solid can, in part, be phenomenologically represented as inelastic or plastic processes in the macroscopic view. However, there are clearly phenomena associated with fracture growth and open fracture fluid flows that produce effects that can not be described using ordinary inelastic phenomenology. This is evident from the fact that a variety of energy release phenomena can occur, including seismic emissions of previously stored strain energy due to fracture growth, release of disolved gas from fluids in the fractures resulting in enhanced buoyancy and subsequent energetic flows of gas and fluids through the fracture system which can produce raid extension of old fractures and the creation of new ones. Additionally, the flows will be modulated by the opening and closing of fractures due to deformation in the solid, so that the flow process is strongly coupled to dynamical processes in the surrounding solid matrix, some of which are induced by the flow itself

The influence of modifications of a fatigue loading history program on fatigue lifetime

Science.gov (United States)

Branger, J.

1972-01-01

Rectangular specimens of 7075 and 2014 aluminum alloys with two holes (stress concentration factor of 3.24) have been tested under axial fatigue loading on a six-rod test bed with modifications of the loading program, the surface particulars, and the frequency. The length of the precrack stage was investigated by use of a new crack detector. In most cases the two alloys behaved similarly, with similar life to crack start under the same loading. Some overloads lengthened the life. Truncation by omission of the lowest peak loads should be limited to about 20 percent of the ultimate load. Simplifying counting methods gave misleading results. Very thin surface layers of anodizing, protection by vinyl, dry nitrogen atmosphere, as well as stepwise reaming or grinding the surface of the holes, lengthened the life; thick anodized layers shortened the life. Compressing the hole surface by rolling had no influence. Frequencies at about 210 to 240 cpm produced shorter lives than those at 40 cpm. At 5.4 cpm the life was considerably longer. A model to better understand the precrack-stage fatigue mechanism is discussed.

A case study review of technical and technology issues for transition of a utility load management program to provide system reliability resources in restructured electricity markets

Energy Technology Data Exchange (ETDEWEB)

Weller, G.H.

2001-07-15

Utility load management programs--including direct load control and interruptible load programs--were employed by utilities in the past as system reliability resources. With electricity industry restructuring, the context for these programs has changed; the market that was once controlled by vertically integrated utilities has become competitive, raising the question: can existing load management programs be modified so that they can effectively participate in competitive energy markets? In the short run, modified and/or improved operation of load management programs may be the most effective form of demand-side response available to the electricity system today. However, in light of recent technological advances in metering, communication, and load control, utility load management programs must be carefully reviewed in order to determine appropriate investments to support this transition. This report investigates the feasibility of and options for modifying an existing utility load management system so that it might provide reliability services (i.e. ancillary services) in the competitive markets that have resulted from electricity industry restructuring. The report is a case study of Southern California Edison's (SCE) load management programs. SCE was chosen because it operates one of the largest load management programs in the country and it operates them within a competitive wholesale electricity market. The report describes a wide range of existing and soon-to-be-available communication, control, and metering technologies that could be used to facilitate the evolution of SCE's load management programs and systems to provision of reliability services. The fundamental finding of this report is that, with modifications, SCE's load management infrastructure could be transitioned to provide critical ancillary services in competitive electricity markets, employing currently or soon-to-be available load control technologies.

Comparison of depth-averaged concentration and bed load flux sediment transport models of dam-break flow

Directory of Open Access Journals (Sweden)

Jia-heng Zhao

2017-10-01

Full Text Available This paper presents numerical simulations of dam-break flow over a movable bed. Two different mathematical models were compared: a fully coupled formulation of shallow water equations with erosion and deposition terms (a depth-averaged concentration flux model, and shallow water equations with a fully coupled Exner equation (a bed load flux model. Both models were discretized using the cell-centered finite volume method, and a second-order Godunov-type scheme was used to solve the equations. The numerical flux was calculated using a Harten, Lax, and van Leer approximate Riemann solver with the contact wave restored (HLLC. A novel slope source term treatment that considers the density change was introduced to the depth-averaged concentration flux model to obtain higher-order accuracy. A source term that accounts for the sediment flux was added to the bed load flux model to reflect the influence of sediment movement on the momentum of the water. In a one-dimensional test case, a sensitivity study on different model parameters was carried out. For the depth-averaged concentration flux model, Manning's coefficient and sediment porosity values showed an almost linear relationship with the bottom change, and for the bed load flux model, the sediment porosity was identified as the most sensitive parameter. The capabilities and limitations of both model concepts are demonstrated in a benchmark experimental test case dealing with dam-break flow over variable bed topography.

Microbial activities in a vertical-flow wetland system treating sewage sludge with high organic loads

Energy Technology Data Exchange (ETDEWEB)

Wang, R. Y.; Perissol, C.; Baldy, V.; Bonin, G.; Korboulewsky, N.

2009-07-01

The rhizosphere is the most active zone in treatment wetlands where take place physicochemical and biological processes between the substrate, plants, microorganisms, and contaminants. Microorganisms play the key role in the mineralisation of organic matter. substrate respiration and phosphatase activities (acid and alkaline) were chosen as indicators of microbial activities, and studied in a vertical-flow wetland system receiving sewage sludge with high organic loads under the Mediterranean climate. (Author)

Load flow analysis for determining the location of NPP power distribution in West Kalimantan

International Nuclear Information System (INIS)

Citra Candranurani; Rizki Finnansyah Setya Budi; Sahala M Lumbanraja

2015-01-01

Electricity crisis condition happened in West Kalimantan (Kalbar) as a result of power plant capacity almost equal to the peak load. The system will experience a shortfall if there are plants that not operating and do not have reserve. The policy of electricity planning until 2022 is replacing diesel power plant with steam power plant. For long-term planning is required the role of new and renewable energy in order to reduce dependency on fossil fuel consumption, such as NPP utilization. The purpose of this study was to determine the optimum location of the NPP power distribution in order to prepare electricity infrastructure. Load flow calculation in this study using ETAP 12.5 software. NPP is planned to supply base load, so the optimum capacity factor is above 80 %. The result show that there are three location where NPP can generate over 80 % of its capacity, namely: Mempawah Substation, Singkawang Substation, and Sambas Substation. The most optimum located in Mempawah Substation with capacity factor 83.5 %. The location of the three Substation are onshore and in line with one requirement for NPP construction, namely: the availability of cooling water. (author)

Bulk-Flow Analysis of Hybrid Thrust Bearings for Advanced Cryogenic Turbopumps

Science.gov (United States)

SanAndres, Luis

1998-01-01

A bulk-flow analysis and computer program for prediction of the static load performance and dynamic force coefficients of angled injection, orifice-compensated hydrostatic/hydrodynamic thrust bearings have been completed. The product of the research is an efficient computational tool for the design of high-speed thrust bearings for cryogenic fluid turbopumps. The study addresses the needs of a growing technology that requires of reliable fluid film bearings to provide the maximum operating life with optimum controllable rotordynamic characteristics at the lowest cost. The motion of a cryogenic fluid on the thin film lands of a thrust bearing is governed by a set of bulk-flow mass and momentum conservation and energy transport equations. Mass flow conservation and a simple model for momentum transport within the hydrostatic bearing recesses are also accounted for. The bulk-flow model includes flow turbulence with fluid inertia advection, Coriolis and centrifugal acceleration effects on the bearing recesses and film lands. The cryogenic fluid properties are obtained from realistic thermophysical equations of state. Turbulent bulk-flow shear parameters are based on Hirs' model with Moody's friction factor equations allowing a simple simulation for machined bearing surface roughness. A perturbation analysis leads to zeroth-order nonlinear equations governing the fluid flow for the thrust bearing operating at a static equilibrium position, and first-order linear equations describing the perturbed fluid flow for small amplitude shaft motions in the axial direction. Numerical solution to the zeroth-order flow field equations renders the bearing flow rate, thrust load, drag torque and power dissipation. Solution to the first-order equations determines the axial stiffness, damping and inertia force coefficients. The computational method uses well established algorithms and generic subprograms available from prior developments. The Fortran9O computer program hydrothrust runs

Characterizing Flow and Suspended Sediment Trends in the Sacramento River Basin, CA Using Hydrologic Simulation Program - FORTRAN (HSPF)

Science.gov (United States)

Stern, M. A.; Flint, L. E.; Flint, A. L.; Wright, S. A.; Minear, J. T.

2014-12-01

A watershed model of the Sacramento River Basin, CA was developed to simulate streamflow and suspended sediment transport to the San Francisco Bay Delta (SFBD) for fifty years (1958-2008) using the Hydrological Simulation Program - FORTRAN (HSPF). To compensate for the large model domain and sparse data, rigorous meteorological development and characterization of hydraulic geometry were employed to spatially distribute climate and hydrologic processes in unmeasured locations. Parameterization techniques sought to include known spatial information for tributaries such as soil information and slope, and then parameters were scaled up or down during calibration to retain the spatial characteristics of the land surface in un-gaged areas. Accuracy was assessed by comparing model calibration to measured streamflow. Calibration and validation of the Sacramento River ranged from "good" to "very good" performance based upon a "goodness-of-fit" statistical guideline. Model calibration to measured sediment loads were underestimated on average by 39% for the Sacramento River, and model calibration to suspended sediment concentrations were underestimated on average by 22% for the Sacramento River. Sediment loads showed a slight decreasing trend from 1958-2008 and was significant (p < 0.0025) in the lower 50% of stream flows. Hypothetical climate change scenarios were developed using the Climate Assessment Tool (CAT). Several wet and dry scenarios coupled with temperature increases were imposed on the historical base conditions to evaluate sensitivity of streamflow and sediment on potential changes in climate. Wet scenarios showed an increase of 9.7 - 17.5% in streamflow, a 7.6 - 17.5% increase in runoff, and a 30 - 93% increase in sediment loads. The dry scenarios showed a roughly 5% decrease in flow and runoff, and a 16 - 18% decrease in sediment loads. The base hydrology was most sensitive to a temperature increase of 1.5 degrees Celsius and an increase in storm intensity and

Monitoring Training Loads in Professional Basketball Players Engaged in a Periodized Training Program.

Science.gov (United States)

Aoki, Marcelo S; Ronda, Lorena T; Marcelino, Pablo R; Drago, Gustavo; Carling, Chris; Bradley, Paul S; Moreira, Alexandre

2017-02-01

Aoki, MS, Ronda, LT, Marcelino, PR, Drago, G, Carling, C, Bradley, PS, and Moreira, A. Monitoring training loads in professional basketball players engaged in a periodized training program. J Strength Cond Res 31(2): 348-358, 2017-The aim of this study was to investigate the dynamics of external training load (eTL) and internal training load (iTL) during seasonal periods, and examine the effect of a periodized training program on physical performance in professional basketball players. Repeated measures for 9 players (28 ± 6 years; 199 ± 8 cm; 101 ± 12 kg) were collected from 45 training sessions, over a 6-week preseason phase and a 5-week in-season phase. Physical tests were conducted at baseline (T1), week 4 (T2), and week 9 (T3). Differences in means are presented as % ± confident limits. A very likely difference was observed during in-season compared with preseason for the eTL variables (measured by multivariable monitoring device), mechanical load (13.5 ± 8.8) and peak acceleration (11.0 ± 11.2), respectively. Regarding iTL responses, a very large decrement in TRIMP (most likely difference, -20.6 ± 3.8) and in session rating of perceived exertion training load (very likely difference, -14.2 ± 9.0) was detected from preseason to in-season. Physical performance improved from T1 to T3 for Yo-Yo intermittent recovery test 1 (62.2 ± 34.3, effect size [ES] > 1.2); countermovement jump (8.8 ± 6.1, ES > 0.6); and squat jump (14.8 ± 10.2, ES > 0.8). Heart rate (HR; %HRpeak) exercise responses during a submaximal running test decreased from T1 to T3 (3.2 ± 4.3, ES 1.2). These results provide valuable information to coaches about training loads and physical performance across different seasonal periods. The data demonstrate that both eTL and iTL measures should be monitored in association with physical tests, to provide a comprehensive understanding of the training process.

Numerical analysis of reactor internals under hydrodynamic loads

Energy Technology Data Exchange (ETDEWEB)

Kim, Da Hye; Chang, Yoon Suk [Kyung Hee Univ., Yongin (Korea, Republic of); Jhung, Myung Jo [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

2013-10-15

In the present study, six kinds of major equipment of a typical reactor internals were identified by incorporating recent research trend. Based on this, detailed numerical models were developed and used for establishment of optimum analysis methodology subjected to hydrodynamic loads. As a result, stress values of the major equipment were calculated through the acoustic-structure analysis under periodic hydrodynamic load and the turbulence-structure analysis under random hydrodynamic load. The numerical analysis scheme can be used for development of preventive action plan and management procedures of the reactor internals. Reactor internals installed in a pressure vessel have been exposed to harsh environment such as high neutron irradiation and temperature with complex fluid flow. As the increase of operational years of NPPs(Nuclear Power Plants), possibility of functional loss of the reactor internals is increased due to degradation caused by radiation embrittlement, thermal aging, fatigue, corrosion and FIV(Flow-Induced Vibration) etc. In practice, defects were detected at core support structure as well as upper and lower parts of structural assembly in European and United States NPPs. Recently, in a GALL(Generic Aging Lessons Learned) report, US NRC(Nuclear Regulatory Commission) identified reactor internals as a high priority component and addressed relevant management programs. In Korea, similar activities have been conducted for long-term operation beyond design lifetime but most of them were limited to qualitative evaluation based on examination and maintenance programs. Therefore, not only to reduce repair and replacement efforts but also to secure the stability of NPPs, necessity for development of quantitative evaluation technique as well as establishment of preventive action plan and management procedures is on the rise. The FIV represents the structural vibration phenomenon induced by liquid flow and generally occurs at contact surfaces. In the present

Compilation of functional languages using flow graph analysis

NARCIS (Netherlands)

Hartel, Pieter H.; Glaser, Hugh; Wild, John M.

A system based on the notion of a flow graph is used to specify formally and to implement a compiler for a lazy functional language. The compiler takes a simple functional language as input and generates C. The generated C program can then be compiled, and loaded with an extensive run-time system to

Effect of sludge retention time on continuous-flow system with enhanced biological phosphorus removal granules at different COD loading.

Science.gov (United States)

Li, Dong; Lv, Yufeng; Zeng, Huiping; Zhang, Jie

2016-11-01

The effect of sludge retention time (SRT) on the continuous-flow system with enhanced biological phosphorus removal (EBPR) granules at different COD loading was investigated during the operation of more than 220days. And the results showed that when the system operated at long SRT (30days) and low COD loading (200mg·L(-1)), it could maintain excellent performance. However, long SRT and high COD loading (300mg·L(-1)) deteriorated the settling ability of granules and the performance of system and resulted in the overgrowth of filamentous bacteria. Meanwhile, the transformation of poly-β-hydroxyalkanoates (PHAs) and glycogen in metabolism process was inhibited. Moreover, the results of pyrosequencing indicated that filamentous bacteria had a competitive advantage over polyphosphate-accumulating organisms (PAOs) at high COD loading and long SRT. The PAOs specious of Candidatus_Accumlibater and system performance increased obviously when the SRT was reduced to 20days at high COD loading. Copyright © 2016 Elsevier Ltd. All rights reserved.

Modeling of a pitching and plunging airfoil using experimental flow field and load measurements

Science.gov (United States)

Troshin, Victor; Seifert, Avraham

2018-01-01

The main goal of the current paper is to outline a low-order modeling procedure of a heaving airfoil in a still fluid using experimental measurements. Due to its relative simplicity, the proposed procedure is applicable for the analysis of flow fields within complex and unsteady geometries and it is suitable for analyzing the data obtained by experimentation. Currently, this procedure is used to model and predict the flow field evolution using a small number of low profile load sensors and flow field measurements. A time delay neural network is used to estimate the flow field. The neural network estimates the amplitudes of the most energetic modes using four sensory inputs. The modes are calculated using proper orthogonal decomposition of the flow field data obtained experimentally by time-resolved, phase-locked particle imaging velocimetry. To permit the use of proper orthogonal decomposition, the measured flow field is mapped onto a stationary domain using volume preserving transformation. The analysis performed by the model showed good estimation quality within the parameter range used in the training procedure. However, the performance deteriorates for cases out of this range. This situation indicates that, to improve the robustness of the model, both the decomposition and the training data sets must be diverse in terms of input parameter space. In addition, the results suggest that the property of volume preservation of the mapping does not affect the model quality as long as the model is not based on the Galerkin approximation. Thus, it may be relaxed for cases with more complex geometry and kinematics.

Program for Analyzing Flows in a Complex Network

Science.gov (United States)

Majumdar, Alok Kumar

2006-01-01

Generalized Fluid System Simulation Program (GFSSP) version 4 is a general-purpose computer program for analyzing steady-state and transient flows in a complex fluid network. The program is capable of modeling compressibility, fluid transients (e.g., water hammers), phase changes, mixtures of chemical species, and such externally applied body forces as gravitational and centrifugal ones. A graphical user interface enables the user to interactively develop a simulation of a fluid network consisting of nodes and branches. The user can also run the simulation and view the results in the interface. The system of equations for conservation of mass, energy, chemical species, and momentum is solved numerically by a combination of the Newton-Raphson and successive-substitution methods.

A hybrid load flow and event driven simulation approach to multi-state system reliability evaluation

International Nuclear Information System (INIS)

George-Williams, Hindolo; Patelli, Edoardo

2016-01-01

Structural complexity of systems, coupled with their multi-state characteristics, renders their reliability and availability evaluation difficult. Notwithstanding the emergence of various techniques dedicated to complex multi-state system analysis, simulation remains the only approach applicable to realistic systems. However, most simulation algorithms are either system specific or limited to simple systems since they require enumerating all possible system states, defining the cut-sets associated with each state and monitoring their occurrence. In addition to being extremely tedious for large complex systems, state enumeration and cut-set definition require a detailed understanding of the system's failure mechanism. In this paper, a simple and generally applicable simulation approach, enhanced for multi-state systems of any topology is presented. Here, each component is defined as a Semi-Markov stochastic process and via discrete-event simulation, the operation of the system is mimicked. The principles of flow conservation are invoked to determine flow across the system for every performance level change of its components using the interior-point algorithm. This eliminates the need for cut-set definition and overcomes the limitations of existing techniques. The methodology can also be exploited to account for effects of transmission efficiency and loading restrictions of components on system reliability and performance. The principles and algorithms developed are applied to two numerical examples to demonstrate their applicability. - Highlights: • A discrete event simulation model based on load flow principles. • Model does not require system path or cut sets. • Applicable to binary and multi-state systems of any topology. • Supports multiple output systems with competing demand. • Model is intuitive and generally applicable.

Preliminary Study on the Damping Effect of a Lateral Damping Buffer under a Debris Flow Load

Directory of Open Access Journals (Sweden)

Zheng Lu

2017-02-01

Full Text Available Simulating the impact of debris flows on structures and exploring the feasibility of applying energy dissipation devices or shock isolators to reduce the damage caused by debris flows can make great contribution to the design of disaster prevention structures. In this paper, we propose a new type of device, a lateral damping buffer, to reduce the vulnerability of building structures to debris flows. This lateral damping buffer has two mechanisms of damage mitigation: when debris flows impact on a building, it acts as a buffer, and when the structure vibrates due to the impact, it acts as a shock absorber, which can reduce the maximum acceleration response and subsequent vibration respectively. To study the effectiveness of such a lateral damping buffer, an impact test is conducted, which mainly involves a lateral damping buffer attached to a two-degree-of-freedom structure under a simulated debris flow load. To enable the numerical study, the equation of motion of the structure along with the lateral damping buffer is derived. A subsequent parametric study is performed to optimize the lateral damping buffer. Finally, a practical design procedure is also provided.

Climate-scale modelling of suspended sediment load in an Alpine catchment debris flow (Rio Cordon-northeastern Italy)

Science.gov (United States)

Diodato, Nazzareno; Mao, Luca; Borrelli, Pasquale; Panagos, Panos; Fiorillo, Francesco; Bellocchi, Gianni

2018-05-01

Pulsing storms and prolonged rainfall can drive hydrological damaging events in mountain regions with soil erosion and debris flow in river catchments. The paper presents a parsimonious model for estimating climate forcing on sediment loads in an Alpine catchment (Rio Cordon, northeastern Italian Alps). Hydroclimatic forcing was interpreted by the novel CliSMSSL (Climate-Scale Modelling of Suspended Sediment Load) model to estimate annual sediment loads. We used annual data on suspended-solid loads monitored at an experimental station from 1987 to 2001 and on monthly precipitation data. The quality of sediment load data was critically examined, and one outlying year was identified and removed from further analyses. This outlier revealed that our model underestimates exceptionally high sediment loads in years characterized by a severe flood event. For all other years, the CliSMSSL performed well, with a determination coefficient (R2) equal to 0.67 and a mean absolute error (MAE) of 129 Mg y-1. The calibrated model for the period 1986-2010 was used to reconstruct sediment loads in the river catchment for historical times when detailed precipitation records are not available. For the period 1810-2010, the model results indicate that the past centuries have been characterized by large interannual to interdecadal fluctuations in the conditions affecting sediment loads. This paper argues that climate-induced erosion processes in Alpine areas and their impact on environment should be given more attention in discussions about climate-driven strategies. Future work should focus on delineating the extents of these findings (e.g., at other catchments of the European Alpine belt) as well as investigating the dynamics for the formation of sediment loads.

Unstable well behaviour in gas well liquid loading

NARCIS (Netherlands)

Belfroid, S.P.C.; Wijhe, A. van

2017-01-01

Liquid loading is the mechanism that is associated with increased liquid hold-up and liquid back flow at lower gas flow rates in gas production wells. In laboratory, most liquid loading experiments are performed at fixed gas and liquid rates (mass flow controlled). In the field, the well behavior is

Contribution of Fuzzy Minimal Cost Flow Problem by Possibility Programming

OpenAIRE

S. Fanati Rashidi; A. A. Noora

2010-01-01

Using the concept of possibility proposed by zadeh, luhandjula ([4,8]) and buckley ([1]) have proposed the possibility programming. The formulation of buckley results in nonlinear programming problems. Negi [6]re-formulated the approach of Buckley by the use of trapezoidal fuzzy numbers and reduced the problem into fuzzy linear programming problem. Shih and Lee ([7]) used the Negi approach to solve a minimum cost flow problem, whit fuzzy costs and the upper and lower bound. ...

Flow analysis of HANARO flow simulated test facility

International Nuclear Information System (INIS)

Park, Yong-Chul; Cho, Yeong-Garp; Wu, Jong-Sub; Jun, Byung-Jin

2002-01-01

The HANARO, a multi-purpose research reactor of 30 MWth open-tank-in-pool type, has been under normal operation since its initial critical in February, 1995. Many experiments should be safely performed to activate the utilization of the NANARO. A flow simulated test facility is being developed for the endurance test of reactivity control units for extended life times and the verification of structural integrity of those experimental facilities prior to loading in the HANARO. This test facility is composed of three major parts; a half-core structure assembly, flow circulation system and support system. The half-core structure assembly is composed of plenum, grid plate, core channel with flow tubes, chimney and dummy pool. The flow channels are to be filled with flow orifices to simulate core channels. This test facility must simulate similar flow characteristics to the HANARO. This paper, therefore, describes an analytical analysis to study the flow behavior of the test facility. The computational flow analysis has been performed for the verification of flow structure and similarity of this test facility assuming that flow rates and pressure differences of the core channel are constant. The shapes of flow orifices were determined by the trial and error method based on the design requirements of core channel. The computer analysis program with standard k - ε turbulence model was applied to three-dimensional analysis. The results of flow simulation showed a similar flow characteristic with that of the HANARO and satisfied the design requirements of this test facility. The shape of flow orifices used in this numerical simulation can be adapted for manufacturing requirements. The flow rate and the pressure difference through core channel proved by this simulation can be used as the design requirements of the flow system. The analysis results will be verified with the results of the flow test after construction of the flow system. (author)

A comparison of four methods to evaluate the effect of a utility residential air-conditioner load control program on peak electricity use

Energy Technology Data Exchange (ETDEWEB)

Newsham, Guy R., E-mail: guy.newsham@nrc-cnrc.gc.ca [National Research Council Canada-Institute for Research in Construction, Building M24, 1200 Montreal Road, Ottawa, Ontario, K1A 0R6 (Canada); Birt, Benjamin J. [National Research Council Canada-Institute for Research in Construction, Building M24, 1200 Montreal Road, Ottawa, Ontario, K1A 0R6 (Canada); Rowlands, Ian H. [University of Waterloo, Ontario (Canada)

2011-10-15

We analyzed the peak load reductions due to a residential direct load control program for air-conditioners in southern Ontario in 2008. In this program, participant thermostats were increased by 2 deg. C for four hours on five event days. We used hourly, whole-house data for 195 participant households and 268 non-participant households, and four different methods of analysis ranging from simple spreadsheet-based comparisons of average loads on event days, to complex time-series regression. Average peak load reductions were 0.2-0.9 kWh/h per household, or 10-35%. However, there were large differences between event days and across event hours, and in results for the same event day/hour, with different analysis methods. There was also a wide range of load reductions between individual households, and only a minority of households contributed to any given event. Policy makers should be aware of how the choice of an analysis method may affect decisions regarding which demand-side management programs to support, and how they might be incentivized. We recommend greater use of time-series methods, although it might take time to become comfortable with their complexity. Further investigation of what type of households contribute most to aggregate load reductions would also help policy makers better target programs. - Highlights: > We analyzed peak load reductions due to residential a/c load control. > We used four methods, ranging from simple comparisons to time-series regression. > Average peak load reductions were 0.2-0.9 kW per household, varying by method. > We recommend a move towards time-series regression for future studies. > A minority of participant households contributed to a given load control event.

Distribution load estimation (DLE)

Energy Technology Data Exchange (ETDEWEB)

Seppaelae, A; Lehtonen, M [VTT Energy, Espoo (Finland)

1998-08-01

The load research has produced customer class load models to convert the customers` annual energy consumption to hourly load values. The reliability of load models applied from a nation-wide sample is limited in any specific network because many local circumstances are different from utility to utility and time to time. Therefore there is a need to find improvements to the load models or, in general, improvements to the load estimates. In Distribution Load Estimation (DLE) the measurements from the network are utilized to improve the customer class load models. The results of DLE will be new load models that better correspond to the loading of the distribution network but are still close to the original load models obtained by load research. The principal data flow of DLE is presented

Long term operation of continuous-flow system with enhanced biological phosphorus removal granules at different COD loading.

Science.gov (United States)

Li, Dong; Lv, Yufeng; Zeng, Huiping; Zhang, Jie

2016-09-01

In this study, a continuous-flow system with enhanced biological phosphorus removal (EBPR) granules was operated at different COD concentrations (200, 300 and 400mgL(-)(1)) to investigate the effect of COD loading on this system. The results showed that when the COD concentration in influent was increased to 400mgL(-)(1), the anaerobic COD removal efficiency and total phosphorus removal efficiency reduced obviously and the settling ability of granules deteriorated due to the proliferation of filamentous bacteria. Moreover, high COD loading inhibited the EPS secretion and destroyed the stability of granules. Results of high-through pyrosequencing indicated that filamentous bacteria had a competitive advantage over polyphosphate-accumulating organisms (PAOs) at high COD loading. The performance of system, settling ability of granules and proportion of PAOs gradually recovered to the initial level after the COD concentration was reduced to 200mgL(-)(1) on day 81. Copyright © 2016 Elsevier Ltd. All rights reserved.

On the calculation of dynamic and heat loads on a three-dimensional body in a hypersonic flow

Science.gov (United States)

Bocharov, A. N.; Bityurin, V. A.; Evstigneev, N. M.; Fortov, V. E.; Golovin, N. N.; Petrovskiy, V. P.; Ryabkov, O. I.; Teplyakov, I. O.; Shustov, A. A.; Solomonov, Yu S.

2018-01-01

We consider a three-dimensional body in a hypersonic flow at zero angle of attack. Our aim is to estimate heat and aerodynamic loads on specific body elements. We are considering a previously developed code to solve coupled heat- and mass-transfer problem. The change of the surface shape is taken into account by formation of the iterative process for the wall material ablation. The solution is conducted on the multi-graphics-processing-unit (multi-GPU) cluster. Five Mach number points are considered, namely for M = 20-28. For each point we estimate body shape after surface ablation, heat loads on the surface and aerodynamic loads on the whole body and its elements. The latter is done using Gauss-type quadrature on the surface of the body. The comparison of the results for different Mach numbers is performed. We also estimate the efficiency of the Navier-Stokes code on multi-GPU and central processing unit architecture for the coupled heat and mass transfer problem.

Effects of interruptible load program on equilibrium outcomes of electricity markets with wind power

Energy Technology Data Exchange (ETDEWEB)

An, Xuena; Zhang, Shaohua; Li, Xue [Shanghai Univ. (China). Key Lab. of Power Station Automation Technology

2013-07-01

High wind power penetration presents a lot of challenges to the flexibility and reliability of power system operation. In this environment, various demand response (DR) programs have got much attention. As an effective measure of demand response programs, interruptible load (IL) programs have been widely used in electricity markets. This paper addresses the problem of impacts of the IL programs on the equilibrium outcomes of electricity wholesale markets with wind power. A Cournot equilibrium model of wholesale markets with wind power is presented, in which IL programs is included by a market demand model. The introduction of the IL programs leads to a non-smooth equilibrium problem. To solve this equilibrium problem, a novel solution method is proposed. Numerical examples show that IL programs can lower market price and its volatility significantly, facilitate the integration of wind power.

EPRI flow-loop/in situ test program for motor-operated valves

International Nuclear Information System (INIS)

Hosler, J.F.; Dorfman, L.S.

1994-01-01

The Electric Power Research Institute is undertaking a comprehensive research program to develop and validate methods for predicting the performance of common motor-operated gate, global, and butterfly valves. To assess motor-operated valve (MOV) performance characteristics and provide a basis for methods validation, full-scale testing was conducted on 62 MOVs. Tests were performed in four flow-loop facilities and in nine nuclear units. Forty-seven gate, five globe, and 10 butterfly valves were tested under a wide range of flow and differential pressure conditions. The paper describes the test program scope, test configurations, instrumentation and data acquisition, testing approach, and data analysis methods. Key results are summarized

High-uranium-loaded U3O8--Al fuel element development program

International Nuclear Information System (INIS)

Martin, M.M.

1978-01-01

The High-Uranium-Loaded U 3 O 8 --Al Fuel Development Program supports Argonne National Laboratory efforts to develop high-uranium-density research and test reactor fuel to accommodate use of low-uranium enrichment. The goal is to fuel most research and test reactors with uranium of less than 20% enrichment for the purpose of lowering the potential for diversion of highly-enriched material for nonpeaceful usages

Using linear programming to analyze and optimize stochastic flow lines

DEFF Research Database (Denmark)

Helber, Stefan; Schimmelpfeng, Katja; Stolletz, Raik

2011-01-01

This paper presents a linear programming approach to analyze and optimize flow lines with limited buffer capacities and stochastic processing times. The basic idea is to solve a huge but simple linear program that models an entire simulation run of a multi-stage production process in discrete time...... programming and hence allows us to solve buffer allocation problems. We show under which conditions our method works well by comparing its results to exact values for two-machine models and approximate simulation results for longer lines....

Experimental and Model Studies on Loading Path-Dependent and Nonlinear Gas Flow Behavior in Shale Fractures

Science.gov (United States)

Li, Honglian; Lu, Yiyu; Zhou, Lei; Tang, Jiren; Han, Shuaibin; Ao, Xiang

2018-01-01

Interest in shale gas as an energy source is growing worldwide. Because the rock's natural fracture system can contribute to gas production, it is important to understand the flow behavior of natural fractures in shale. Previous studies on the flow characteristics in shale fractures were limited and did not consider the effect of nonlinearity. To understand the basic mechanics of the gas flow behavior in shale fractures, laboratory investigations with consideration of the fluid pressure gradient, the confining stress, the loading history and the fracture geometry were conducted in this paper. Izbash's equation was used to analyze the nonlinearity of the flow. The results show that the behavior of the friction factors is similar to that shown in flow tests in smooth and rough pipes. The increase of the confining stress and the irreversible damage to the shale decreased the hydraulic aperture and increased the relative roughness. Thus, turbulent flow could appear at a low Reynolds number, resulting in a significant pressure loss. The limits of the cubic law and the existing correction factor for transmissivity are discussed. It is found that the previous friction models overestimate the friction factor in the laminar regime and underestimate the friction factor in the turbulent regime. For this reason, a new friction model based on a linear combination of the Reynolds number and the relative roughness was developed.

An improved risk-explicit interval linear programming model for pollution load allocation for watershed management.

Science.gov (United States)

Xia, Bisheng; Qian, Xin; Yao, Hong

2017-11-01

Although the risk-explicit interval linear programming (REILP) model has solved the problem of having interval solutions, it has an equity problem, which can lead to unbalanced allocation between different decision variables. Therefore, an improved REILP model is proposed. This model adds an equity objective function and three constraint conditions to overcome this equity problem. In this case, pollution reduction is in proportion to pollutant load, which supports balanced development between different regional economies. The model is used to solve the problem of pollution load allocation in a small transboundary watershed. Compared with the REILP original model result, our model achieves equity between the upstream and downstream pollutant loads; it also overcomes the problem of greatest pollution reduction, where sources are nearest to the control section. The model provides a better solution to the problem of pollution load allocation than previous versions.

Motion of a cylinder adjacent to a free-surface: flow patterns and loading

Energy Technology Data Exchange (ETDEWEB)

Zhu, Q.; Lin, J.C. [Lehigh Univ., Bethlehem, PA (United States). Dept. of Mechanical Engineering and Mechanics; Unal, M.F.; Rockwell, D.

2000-06-01

The flow structure and loading due to combined translatory and sinusoidal motion of a cylinder adjacent to a free-surface are characterized using a cinema technique of high-image-density particle image velocimetry and simultaneous force measurements. The instantaneous patterns of vorticity and streamline topology are interpreted as a function of degree of submergence beneath the free-surface. The relative magnitudes of the peak vorticity and the circulation of vortices formed from the upper and lower surfaces of the cylinder, as well as vortex formation from the free-surface, are remarkably affected by the nominal submergence. The corresponding streamline topology, interpreted in terms of foci, saddle points, and multiple separation and reattachment points also exhibit substantial changes with submergence. All of these features affect the instantaneous loading of the cylinder. Calculation of instantaneous moments of vorticity and the incremental changes in these moments during the cylinder motion allow identification of those vortices that contribute most substantially to the instantaneous lift and drag. Furthermore, the calculated moments are in general accord with the time integrals of the measured lift and drag acting on the cylinder for sufficiently large submergence. (orig.)

A Computer Program for Flow-Log Analysis of Single Holes (FLASH)

Science.gov (United States)

Day-Lewis, F. D.; Johnson, C.D.; Paillet, Frederick L.; Halford, K.J.

2011-01-01

A new computer program, FLASH (Flow-Log Analysis of Single Holes), is presented for the analysis of borehole vertical flow logs. The code is based on an analytical solution for steady-state multilayer radial flow to a borehole. The code includes options for (1) discrete fractures and (2) multilayer aquifers. Given vertical flow profiles collected under both ambient and stressed (pumping or injection) conditions, the user can estimate fracture (or layer) transmissivities and far-field hydraulic heads. FLASH is coded in Microsoft Excel with Visual Basic for Applications routines. The code supports manual and automated model calibration. ?? 2011, The Author(s). Ground Water ?? 2011, National Ground Water Association.

Performance characteristics of axisymmetric venturi-like reverse-flow diverters. Consolidated Fuel Reprocessing Program

International Nuclear Information System (INIS)

Smith, G.V.; Counce, R.M.

1984-01-01

This paper presents experimental and model-predicted pressure-flow characteristics of axisymmetric venturi-like reverse-flow diverters (RFDs), the key component of fluid pumping systems utilized for the transport of hazardous fluids. The effects of several key geometric parameters, operating conditions, and fluid properties on the performance of the RFD are presented and compared to model predictions. The results indicate good agreement between data and theory over a large portion of the range of variables studied. Cavitation is observed to be the primary factor in limiting the performance of the RFD at small values of load impedances

Design And Modeling An Automated Digsilent Power System For Optimal New Load Locations

Directory of Open Access Journals (Sweden)

Mohamed Saad

2015-08-01

Full Text Available Abstract The electric power utilities seek to take advantage of novel approaches to meet growing energy demand. Utilities are under pressure to evolve their classical topologies to increase the usage of distributed generation. Currently the electrical power engineers in many regions of the world are implementing manual methods to measure power consumption for farther assessment of voltage violation. Such process proved to be time consuming costly and inaccurate. Also demand response is a grid management technique where retail or wholesale customers are requested either electronically or manually to reduce their load. Therefore this paper aims to design and model an automated power system for optimal new load locations using DPL DIgSILENT Programming Language. This study is a diagnostic approach that assists system operator about any voltage violation cases that would happen during adding new load to the grid. The process of identifying the optimal bus bar location involves a complicated calculation of the power consumptions at each load bus As a result the DPL program would consider all the IEEE 30 bus internal networks data then a load flow simulation will be executed. To add the new load to the first bus in the network. Therefore the developed model will simulate the new load at each available bus bar in the network and generate three analytical reports for each case that captures the overunder voltage and the loading elements among the grid.

Adaptation of perceptual responses to low-load blood flow restriction training

DEFF Research Database (Denmark)

Martín-Hernández, Juan; Ruiz-Aguado, Jorge; Herrero, Azael Juan

2017-01-01

The purpose of this study was to determine the adaptive response of ratings of perceived exertion (RPE) and pain over six consecutive training sessions. Thirty subjects were assigned to either a blood flow restricted training group (BFRT) or a high intensity group (HIT). BFRT group performed four...... sets (30+15+15+15, respectively) of unilateral leg extension at an intensity of 20% one repetition maximum (1RM) while a restrictive cuff was applied to the most proximal part of the leg. HIT group performed 3 sets of eight repetitions with 85%1RM. RPE and pain were assessed following every exercise.......01). No between-group differences were found at any time point. In summary, BFRT induces a high perceptual response to training. However, this perceptual response is rapidly attenuated, leading to values similar to those experienced during HIT. Low load BFRT should not be limited to highly motivated individuals...

Ballast Load Control of Turbine-Generator Sets in the Micro-Hydro Range with a Turbine that has no Flow Regulating Value

Directory of Open Access Journals (Sweden)

Valentin Nedelea

2011-09-01

Full Text Available This paper presents the effects of voltage and frequency variation on users load supplies from electrical supply system generated from small micro-hydro plants. Induction generators operate as stand-alone self excited by capacitors and turbine has no flow regulating valve. Many conventional and non conventional approaches are described to govern turbine-generator set to ensure a steady frequency and voltage level. A load controller increases or decreases a ballast load connected across the generator as the user load varies, to keep frequency and voltage variation in standard limits. To design a controller for self excited induction generator, researches were performed on asynchronous generator with double winding stator to analyse steady state open loop behaviour. The results on the behaviour of the unregulated turbine (DC motor – generator system was presented.

Mindstorms robots and the application of cognitive load theory in introductory programming

Science.gov (United States)

Mason, Raina; Cooper, Graham

2013-12-01

This paper reports on a series of introductory programming workshops, initially targeting female high school students, which utilised Lego Mindstorms robots. Cognitive load theory (CLT) was applied to the instructional design of the workshops, and a controlled experiment was also conducted investigating aspects of the interface. Results indicated that a truncated interface led to better learning by novice programmers as measured by test performance by participants, as well as enhanced shifts in self-efficacy and lowered perception of difficulty. There was also a transfer effect to another programming environment (Alice). It is argued that the results indicate that for novice programmers, the mere presence on-screen of additional (redundant) entities acts as a form of tacit distraction, thus impeding learning. The utility of CLT to analyse, design and deliver aspects of computer programming environments and instructional materials is discussed.

Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE) Version 5.0: Data loading manual. Volume 10

International Nuclear Information System (INIS)

VanHorn, R.L.; Wolfram, L.M.; Fowler, R.D.; Beck, S.T.; Smith, C.L.

1995-04-01

The Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE) suite of programs can be used to organize and standardize in an electronic format information from probabilistic risk assessments or individual plant examinations. The Models and Results Database (MAR-D) program of the SAPHIRE suite serves as the repository for probabilistic risk assessment and individual plant examination data and information. This report demonstrates by examples the common electronic and manual methods used to load these types of data. It is not a stand alone document but references documents that contribute information relative to the data loading process. This document provides a more detailed discussion and instructions for using SAPHIRE 5.0 only when enough information on a specific topic is not provided by another available source

Impact of heat load location and strength on air flow pattern with a passive chilled beam system

Energy Technology Data Exchange (ETDEWEB)

Kosonen, Risto [Halton Oy, Niittyvillankuja 4, 01510 Vantaa (Finland); Saarinen, Pekka; Koskela, Hannu [Finnish Institute of Occupational Health, Lemminkaisenkatu 14-18 B, 20520 Turku (Finland); Hole, Alex [Arup, Rob Leslie-Carter, Level 10, 201 Kent Street, Sydney, NSW 2000 (Australia)

2010-01-15

A passive chilled beam is a source of natural convection, creating a flow of cold air directly into the occupied zone. Experiments were conducted in a mock-up of an office room to study the air velocities in the occupied spaces. In addition, velocity profiles are registered when underneath heat loads exist and the cool and warm air flows interact. Experimental laboratory study revealed that in the case of the underneath heat gains, even no upward plume was generated and the dummy only acted as a flow obstacle, having a significant effect on the velocity profile. Furthermore, in an actual occupied office environment, the thermal plumes and the supply air diffuser mixed effectively the whole air volume. The maximum air velocity measured was still below 0.25 m/s with the extremely high heat gain of 164 W/m{sup 2}. The results demonstrate that analysis methods were the interaction of convection flow and jet are not taken into account could not accurately describe air movement and draught risk in the occupied room space. (author)

EPRI MOV performance prediction program

International Nuclear Information System (INIS)

Hosler, J.F.; Damerell, P.S.; Eidson, M.G.; Estep, N.E.

1994-01-01

An overview of the EPRI Motor-Operated Valve (MOV) Performance Prediction Program is presented. The objectives of this Program are to better understand the factors affecting the performance of MOVs and to develop and validate methodologies to predict MOV performance. The Program involves valve analytical modeling, separate-effects testing to refine the models, and flow-loop and in-plant MOV testing to provide a basis for model validation. The ultimate product of the Program is an MOV Performance Prediction Methodology applicable to common gate, globe, and butterfly valves. The methodology predicts thrust and torque requirements at design-basis flow and differential pressure conditions, assesses the potential for gate valve internal damage, and provides test methods to quantify potential for gate valve internal damage, and provides test methods to quantify potential variations in actuator output thrust with loading condition. Key findings and their potential impact on MOV design and engineering application are summarized

Constituent concentrations, loads, and yields to Beaver Lake, Arkansas, water years 1999-2008

Science.gov (United States)

Bolyard, Susan E.; De Lanois, Jeanne L.; Green, W. Reed

2010-01-01

Beaver Lake is a large, deep-storage reservoir used as a drinking-water supply and considered a primary watershed of concern in the State of Arkansas. As such, information is needed to assess water quality, especially nutrient enrichment, nutrient-algal relations, turbidity, and sediment issues within the reservoir system. Water-quality samples were collected at three main inflows to Beaver Lake: the White River near Fayetteville, Richland Creek at Goshen, and War Eagle Creek near Hindsville. Water-quality samples collected over the period represented different flow conditions (from low to high). Constituent concentrations, flow-weighted concentrations, loads, and yields from White River, Richland Creek, and War Eagle Creek to Beaver Lake for water years 1999-2008 were documented for this report. Constituents include total ammonia plus organic nitrogen, dissolved nitrite plus nitrate nitrogen, dissolved orthophosphorus (soluble reactive phosphorus), total phosphorus, total nitrogen, dissolved organic carbon, total organic carbon, and suspended sediment. Linear regression models developed by computer program S-LOADEST were used to estimate loads for each constituent for the 10-year period at each station. Constituent yields and flow-weighted concentrations for each of the three stations were calculated for the study. Constituent concentrations and loads and yields varied with time and varied among the three tributaries contributing to Beaver Lake. These differences can result from differences in precipitation, land use, contributions of nutrients from point sources, and variations in basin size. Load and yield estimates varied yearly during the study period, water years 1999-2008, with the least nutrient and sediment load and yields generally occurring in water year 2006, and the greatest occurring in water year 2008, during a year with record amounts of precipitation. Flow-weighted concentrations of most constituents were greatest at War Eagle Creek near Hindsville

OL1/OL2 License renewal for extended life-time: Class 1 piping load and strength analyses

International Nuclear Information System (INIS)

Lemettinen, P.

2015-01-01

Teollisuuden Voima Oyj (TVO) operates two NPP units Olkiluoto 1 (OL1) and Olkiluoto 2 (OL2), that are identical 880 MWe BWRs. The units were originally designed for 40 years life-time. TVO is applying license renewal for extended life-time for 60 years plant life. Part of the license renewal project is to evaluate and update all Class 1 piping load and strength analyses. These analyses are done with the help of TVO's in-house Piping and Component Analysis and Monitoring System (PAMS). PAMS is basically a database system, consisting of separate geometry, material, loading, result and document databases. The thermo hydraulic analysis program RELAP5 is used to obtain temperature, pressure and mass flow for the piping loading areas. The piping strength analysis are carried out mainly with the Finnish FPIPE FEA program for all related thermal transient and dynamic load cases. The slides of the presentation have been added to the paper

An alternative method for centrifugal compressor loading factor modelling

Science.gov (United States)

Galerkin, Y.; Drozdov, A.; Rekstin, A.; Soldatova, K.

2017-08-01

The loading factor at design point is calculated by one or other empirical formula in classical design methods. Performance modelling as a whole is out of consideration. Test data of compressor stages demonstrates that loading factor versus flow coefficient at the impeller exit has a linear character independent of compressibility. Known Universal Modelling Method exploits this fact. Two points define the function - loading factor at design point and at zero flow rate. The proper formulae include empirical coefficients. A good modelling result is possible if the choice of coefficients is based on experience and close analogs. Earlier Y. Galerkin and K. Soldatova had proposed to define loading factor performance by the angle of its inclination to the ordinate axis and by the loading factor at zero flow rate. Simple and definite equations with four geometry parameters were proposed for loading factor performance calculated for inviscid flow. The authors of this publication have studied the test performance of thirteen stages of different types. The equations are proposed with universal empirical coefficients. The calculation error lies in the range of plus to minus 1,5%. The alternative model of a loading factor performance modelling is included in new versions of the Universal Modelling Method.

SAP3PR: a FORTRAN program for calculating equivalent nodal loads resulting from pressure on the faces of 8- to 20-node isoparametric elements

International Nuclear Information System (INIS)

Fanning, D.N.

1978-04-01

A computer program is described for calculating the equivalent nodal loads resulting from distributed loads on a three-dimensional finite-element model. Included is a listing of the computer program, a description of the input data, and an example of the output

Computer programs for the numerical modelling of water flow in rock masses

International Nuclear Information System (INIS)

Croney, P.; Richards, L.R.

1985-08-01

Water flow in rock joints provides a very important possible route for the migration of radio-nuclides from radio-active waste within a repository back to the biosphere. Two computer programs DAPHNE and FPM have been developed to model two dimensional fluid flow in jointed rock masses. They have been developed to run on microcomputer systems suitable for field locations. The fluid flows in a number of jointed rock systems have been examined and certain controlling functions identified. A methodology has been developed for assessing the anisotropic permeability of jointed rock. A number of examples of unconfined flow into surface and underground openings have been analysed and ground water lowering, pore water pressures and flow quantities predicted. (author)

Dry fermentation of manure with straw in continuous plug flow reactor: Reactor development and process stability at different loading rates.

Science.gov (United States)

Patinvoh, Regina J; Kalantar Mehrjerdi, Adib; Sárvári Horváth, Ilona; Taherzadeh, Mohammad J

2017-01-01

In this work, a plug flow reactor was developed for continuous dry digestion processes and its efficiency was investigated using untreated manure bedded with straw at 22% total solids content. This newly developed reactor worked successfully for 230days at increasing organic loading rates of 2.8, 4.2 and 6gVS/L/d and retention times of 60, 40 and 28days, respectively. Organic loading rates up to 4.2gVS/L/d gave a better process stability, with methane yields up to 0.163LCH 4 /gVS added /d which is 56% of the theoretical yield. Further increase of organic loading rate to 6gVS/L/d caused process instability with lower volatile solid removal efficiency and cellulose degradation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Mathematical Model and Program for the Sizing of Counter-flow Natural Draft Wet Cooling Towers

Directory of Open Access Journals (Sweden)

Victor-Eduard Cenușă

2017-08-01

Full Text Available Assuring the necessary temperature and mass flow rate of the cooling water to the condenser represents an essential condition for the efficient operation of a steam power plant. The paper presents equations which describe the physical phenomena and the mathematical model for the design of counter-flow natural draft wet cooling towers. Following is given the flow-chart of the associated computer program. A case study is made to show the results of the computer program and emphasize the interdependence between the main design parameters.

Modeling pesticide loadings from the San Joaquin watershed into the Sacramento-San Joaquin Delta using SWAT

Science.gov (United States)

Chen, H.; Zhang, M.

2016-12-01

The Sacramento-San Joaquin Delta is an ecologically rich, hydrologically complex area that serves as the hub of California's water supply. However, pesticides have been routinely detected in the Delta waterways, with concentrations exceeding the benchmark for the protection of aquatic life. Pesticide loadings into the Delta are partially attributed to the San Joaquin watershed, a highly productive agricultural watershed located upstream. Therefore, this study aims to simulate pesticide loadings to the Delta by applying the Soil and Water Assessment Tool (SWAT) model to the San Joaquin watershed, under the support of the USDA-ARS Delta Area-Wide Pest Management Program. Pesticide use patterns in the San Joaquin watershed were characterized by combining the California Pesticide Use Reporting (PUR) database and GIS analysis. Sensitivity/uncertainty analyses and multi-site calibration were performed in the simulation of stream flow, sediment, and pesticide loads along the San Joaquin River. Model performance was evaluated using a combination of graphic and quantitative measures. Preliminary results indicated that stream flow was satisfactorily simulated along the San Joaquin River and the major eastern tributaries, whereas stream flow was less accurately simulated in the western tributaries, which are ephemeral small streams that peak during winter storm events and are mainly fed by irrigation return flow during the growing season. The most sensitive parameters to stream flow were CN2, SOL_AWC, HRU_SLP, SLSUBBSN, SLSOIL, GWQMN and GW_REVAP. Regionalization of parameters is important as the sensitivity of parameters vary significantly spatially. In terms of evaluation metric, NSE tended to overrate model performance when compared to PBIAS. Anticipated results will include (1) pesticide use pattern analysis, (2) calibration and validation of stream flow, sediment, and pesticide loads, and (3) characterization of spatial patterns and temporal trends of pesticide yield.

Forecasting Shaharchay River Flow in Lake Urmia Basin using Genetic Programming and M5 Model Tree

Directory of Open Access Journals (Sweden)

S. Samadianfard

2017-01-01

Full Text Available Introduction: Precise prediction of river flows is the key factor for proper planning and management of water resources. Thus, obtaining the reliable methods for predicting river flows has great importance in water resource engineering. In the recent years, applications of intelligent methods such as artificial neural networks, fuzzy systems and genetic programming in water science and engineering have been grown extensively. These mentioned methods are able to model nonlinear process of river flows without any need to geometric properties. A huge number of studies have been reported in the field of using intelligent methods in water resource engineering. For example, Noorani and Salehi (23 presented a model for predicting runoff in Lighvan basin using adaptive neuro-fuzzy network and compared the performance of it with neural network and fuzzy inference methods in east Azerbaijan, Iran. Nabizadeh et al. (21 used fuzzy inference system and adaptive neuro-fuzzy inference system in order to predict river flow in Lighvan river. Khalili et al. (13 proposed a BL-ARCH method for prediction of flows in Shaharchay River in Urmia. Khu et al. (16 used genetic programming for runoff prediction in Orgeval catchment in France. Firat and Gungor (11 evaluated the fuzzy-neural model for predicting Mendes river flow in Turkey. The goal of present study is comparing the performance of genetic programming and M5 model trees for prediction of Shaharchay river flow in the basin of Lake Urmia and obtaining a comprehensive insight of their abilities. Materials and Methods: Shaharchay river as a main source of providing drinking water of Urmia city and agricultural needs of surrounding lands and finally one of the main input sources of Lake Urmia is quite important in the region. For obtaining the predetermined goals of present study, average monthly flows of Shaharchay River in Band hydrometric station has been gathered from 1951 to 2011. Then, two third of mentioned

High-Uranium-Loaded U3O8-Al fuel element development program. Part 1

International Nuclear Information System (INIS)

Martin, M.M.

1993-01-01

The High-Uranium-Loaded U 3 O 8 -Al Fuel Element Development Program supports Argonne National Laboratory efforts to develop high-uranium-density research and test reactor fuel to accommodate use of low-uranium enrichment. The goal is to fuel most research and test reactors with uranium of less than 20% enrichment for the purpose of lowering the potential for diversion of highly-enriched material for nonpeaceful usages. The specific objective of the program is to develop the technological and engineering data base for U 3 O 8 -Al plate-type fuel elements of maximal uranium content to the point of vendor qualification for full scale fabrication on a production basis. A program and management plan that details the organization, supporting objectives, schedule, and budget is in place and preparation for fuel and irradiation studies is under way. The current programming envisions a program of about four years duration for an estimated cost of about two million dollars. During the decades of the fifties and sixties, developments at Oak Ridge National Laboratory led to the use of U 3 O 8 -Al plate-type fuel elements in the High Flux Isotope Reactor, Oak Ridge Research Reactor, Puerto Rico Nuclear Center Reactor, and the High Flux Beam Reactor. Most of the developmental information however applies only up to a uranium concentration of about 55 wt % (about 35 vol % U 3 O 8 ). The technical issues that must be addressed to further increase the uranium loading beyond 55 wt % U involve plate fabrication phenomena of voids and dogboning, fuel behavior under long irradiation, and potential for the thermite reaction between U 3 O 8 and aluminum

Evaluation of load flow and grid expansion in a unit-commitment and expansion optimization model SciGRID International Conference on Power Grid Modelling

Science.gov (United States)

Senkpiel, Charlotte; Biener, Wolfgang; Shammugam, Shivenes; Längle, Sven

2018-02-01

Energy system models serve as a basis for long term system planning. Joint optimization of electricity generating technologies, storage systems and the electricity grid leads to lower total system cost compared to an approach in which the grid expansion follows a given technology portfolio and their distribution. Modelers often face the problem of finding a good tradeoff between computational time and the level of detail that can be modeled. This paper analyses the differences between a transport model and a DC load flow model to evaluate the validity of using a simple but faster transport model within the system optimization model in terms of system reliability. The main findings in this paper are that a higher regional resolution of a system leads to better results compared to an approach in which regions are clustered as more overloads can be detected. An aggregation of lines between two model regions compared to a line sharp representation has little influence on grid expansion within a system optimizer. In a DC load flow model overloads can be detected in a line sharp case, which is therefore preferred. Overall the regions that need to reinforce the grid are identified within the system optimizer. Finally the paper recommends the usage of a load-flow model to test the validity of the model results.

Contribution of Fuzzy Minimal Cost Flow Problem by Possibility Programming

Directory of Open Access Journals (Sweden)

S. Fanati Rashidi

2010-06-01

Full Text Available Using the concept of possibility proposed by zadeh, luhandjula ([4,8] and buckley ([1] have proposed the possibility programming. The formulation of buckley results in nonlinear programming problems. Negi [6]re-formulated the approach of Buckley by the use of trapezoidal fuzzy numbers and reduced the problem into fuzzy linear programming problem. Shih and Lee ([7] used the Negi approach to solve a minimum cost flow problem, whit fuzzy costs and the upper and lower bound. In this paper we shall consider the general form of this problem where all of the parameters and variables are fuzzy and also a model for solving is proposed

Temporal trends in water-quality constituent concentrations and annual loads of chemical constituents in Michigan watersheds, 1998–2013

Science.gov (United States)

Hoard, Christopher J.; Fogarty, Lisa R.; Duris, Joseph W.

2018-02-21

In 1998, the Michigan Department of Environmental Quality and the U.S. Geological Survey began the Water Chemistry Monitoring Program for select streams in the State of Michigan. Objectives of this program were to provide assistance with (1) statewide water-quality assessments, (2) the National Pollutant Discharge Elimination System permitting process, and (3) water-resource management decisions. As part of this program, water-quality data collected from 1998 to 2013 were analyzed to identify potential trends for select constituents that were sampled. Sixteen water-quality constituents were analyzed at 32 stations throughout Michigan. Trend analysis on the various water-quality data was done using either the uncensored Seasonal Kendall test or through Tobit regression. In total, 79 trends were detected in the constituents analyzed for 32 river stations sampled for the study period—53 downward trends and 26 upward trends were detected. The most prevalent trend detected throughout the State was for ammonia, with 11 downward trends and 1 upward trend estimated.In addition to trends, constituent loads were estimated for 31 stations from 2002 to 2013 for stations that were sampled 12 times per year. Loads were computed using the Autobeale load computation program, which used the Beale ratio estimator approach to estimate an annual load. Constituent loads were the largest in large watershed streams with the highest annual flows such as the Saginaw and Grand Rivers. Likewise, constituent loads were the smallest in smaller tributaries that were sampled as part of this program such as the Boardman and Thunder Bay Rivers.

Advanced non-linear flow-induced vibration and fretting-wear analysis capabilities

Energy Technology Data Exchange (ETDEWEB)

Toorani, M.; Pan, L.; Li, R.; Idvorian, N. [Babcock and Wilcox Canada Ltd., Cambridge, Ontario (Canada); Vincent, B.

2009-07-01

Fretting wear is a potentially significant degradation mechanism in nuclear steam generators and other shell and tube heat transfer equipment as well. This paper presents an overview of the recently developed code FIVDYNA which is used for the non-linear flow-induced vibration and fretting wear analysis for operating steam generators (OTSG and RSG) and shell-and-tube heat exchangers. FIVDYNA is a non-linear time-history Flow-Induced Vibration (FIV) analysis computer program that has been developed by Babcock and Wilcox Canada to advance the understanding of tube vibration and tube to tube-support interaction. In addition to the dynamic fluid induced forces the program takes into account other tube static forces due to axial and lateral tube preload and thermal interaction loads. The program is capable of predicting the location where the fretting wear is most likely to occur and its magnitude taking into account the support geometry including gaps. FIVDYNA uses the general purpose finite element computer code ABAQUS as its solver. Using ABAQUS gives the user the flexibility to add additional forces to the tube ranging from tube preloads and the support offsets to thermal loads. The forces currently being modeled in FIVDYNA are the random turbulence, steady drag force, fluid-elastic forces, support offset and pre-strain force (axial loads). This program models the vibration of tubes and calculates the structural dynamic characteristics, and interaction forces between the tube and the tube supports. These interaction forces are then used to calculate the work rate at the support and eventually the predicted depth of wear scar on the tube. A very good agreement is found with experiments and also other computer codes. (author)

The effect of gas and fluid flows on nonlinear lateral vibrations of rotating drill strings

Science.gov (United States)

Khajiyeva, Lelya; Kudaibergenov, Askar; Kudaibergenov, Askat

2018-06-01

In this work we develop nonlinear mathematical models describing coupled lateral vibrations of a rotating drill string under the effect of external supersonic gas and internal fluid flows. An axial compressive load and a torque also affect the drill string. The mathematical models are derived by the use of Novozhilov's nonlinear theory of elasticity with implementation of Hamilton's variation principle. Expressions for the gas flow pressure are determined according to the piston theory. The fluid flow is considered as added mass inside the curved tube of the drill string. Using an algorithm developed in the Mathematica computation program on the basis of the Galerkin approach and the stiffness switching method the numerical solution of the obtained approximate differential equations is found. Influences of the external loads, drill string angular speed of rotation, parameters of the gas and fluid flows on the drill string vibrations are shown.

Static and dynamic load-balancing strategies for parallel reservoir simulation

International Nuclear Information System (INIS)

Anguille, L.; Killough, J.E.; Li, T.M.C.; Toepfer, J.L.

1995-01-01

Accurate simulation of the complex phenomena that occur in flow in porous media can tax even the most powerful serial computers. Emergence of new parallel computer architectures as a future efficient tool in reservoir simulation may overcome this difficulty. Unfortunately, major problems remain to be solved before using parallel computers commercially: production serial programs must be rewritten to be efficient in parallel environments and load balancing methods must be explored to evenly distribute the workload on each processor during the simulation. This study implements both a static load-balancing algorithm and a receiver-initiated dynamic load-sharing algorithm to achieve high parallel efficiencies on both the IBM SP2 and Intel IPSC/860 parallel computers. Significant speedup improvement was recorded for both methods. Further optimization of these algorithms yielded a technique with efficiencies as high as 90% and 70% on 8 and 32 nodes, respectively. The increased performance was the result of the minimization of message-passing overhead

Calculation of pressure drop and flow redistribution in the LMFBR core

International Nuclear Information System (INIS)

Morgado, O.J.

1984-01-01

The flow redistribution through fuel assemblies of LMFBRs: for the correct calculation of mass flow rates and pressure drop, are studied. Using a quasi-static formulation of conservation equations of mass and energy, a computer program was developed to simulate any arbitrary number of flow channels, operating at different linear power levels. Therefore f flow channels, operating at different linear power levels. Therefore, it was possible to perform thermal transient calculations for the Clinch River reactor core. The results of the calculations agree with the data found in the literature and supply accurate information about flow redistribution, average temperature, and pressure drop in the core, when the reactor is operated at conditions from the designed flow conditions, as is always the case in a load changing operation, or during transients. (Autor) [pt

Influence of sampling frequency and load calculation methods on quantification of annual river nutrient and suspended solids loads.

Science.gov (United States)

Elwan, Ahmed; Singh, Ranvir; Patterson, Maree; Roygard, Jon; Horne, Dave; Clothier, Brent; Jones, Geoffrey

2018-01-11

Better management of water quality in streams, rivers and lakes requires precise and accurate estimates of different contaminant loads. We assessed four sampling frequencies (2 days, weekly, fortnightly and monthly) and five load calculation methods (global mean (GM), rating curve (RC), ratio estimator (RE), flow-stratified (FS) and flow-weighted (FW)) to quantify loads of nitrate-nitrogen (NO 3 - -N), soluble inorganic nitrogen (SIN), total nitrogen (TN), dissolved reactive phosphorus (DRP), total phosphorus (TP) and total suspended solids (TSS), in the Manawatu River, New Zealand. The estimated annual river loads were compared to the reference 'true' loads, calculated using daily measurements of flow and water quality from May 2010 to April 2011, to quantify bias (i.e. accuracy) and root mean square error 'RMSE' (i.e. accuracy and precision). The GM method resulted into relatively higher RMSE values and a consistent negative bias (i.e. underestimation) in estimates of annual river loads across all sampling frequencies. The RC method resulted in the lowest RMSE for TN, TP and TSS at monthly sampling frequency. Yet, RC highly overestimated the loads for parameters that showed dilution effect such as NO 3 - -N and SIN. The FW and RE methods gave similar results, and there was no essential improvement in using RE over FW. In general, FW and RE performed better than FS in terms of bias, but FS performed slightly better than FW and RE in terms of RMSE for most of the water quality parameters (DRP, TP, TN and TSS) using a monthly sampling frequency. We found no significant decrease in RMSE values for estimates of NO 3 - N, SIN, TN and DRP loads when the sampling frequency was increased from monthly to fortnightly. The bias and RMSE values in estimates of TP and TSS loads (estimated by FW, RE and FS), however, showed a significant decrease in the case of weekly or 2-day sampling. This suggests potential for a higher sampling frequency during flow peaks for more precise

VNAP2: a computer program for computation of two-dimensional, time-dependent, compressible, turbulent flow

Energy Technology Data Exchange (ETDEWEB)

Cline, M.C.

1981-08-01

VNAP2 is a computer program for calculating turbulent (as well as laminar and inviscid), steady, and unsteady flow. VNAP2 solves the two-dimensional, time-dependent, compressible Navier-Stokes equations. The turbulence is modeled with either an algebraic mixing-length model, a one-equation model, or the Jones-Launder two-equation model. The geometry may be a single- or a dual-flowing stream. The interior grid points are computed using the unsplit MacCormack scheme. Two options to speed up the calculations for high Reynolds number flows are included. The boundary grid points are computed using a reference-plane-characteristic scheme with the viscous terms treated as source functions. An explicit artificial viscosity is included for shock computations. The fluid is assumed to be a perfect gas. The flow boundaries may be arbitrary curved solid walls, inflow/outflow boundaries, or free-jet envelopes. Typical problems that can be solved concern nozzles, inlets, jet-powered afterbodies, airfoils, and free-jet expansions. The accuracy and efficiency of the program are shown by calculations of several inviscid and turbulent flows. The program and its use are described completely, and six sample cases and a code listing are included.

Numerical Simulation of Pulsation Flow in the Vapour Channel of Short Low Temperature Heat Pipes at High Heat Loads

Science.gov (United States)

Seryakov, A. V.; Konkin, A. V.

2017-11-01

The results of the numerical simulation of pulsations in the Laval-liked vapour channel of short low-temperature range heat pipes (HPs) are presented. The numerical results confirmed the experimentally obtained increase of the frequency of pulsations in the vapour channel of short HPs with increasing overheat of the porous evaporator relative to the boiling point of the working fluid. The occurrence of pressure pulsations inside the vapour channel in a short HPs is a complex phenomenon associated with the boiling beginning in the capillary-porous evaporator at high heat loads, and appearance the excess amount of vapour above it, leading to the increase in pressure P to a value at which the boiling point TB of the working fluid becomes higher than the evaporator temperature Tev. Vapour clot spreads through the vapour channel and condense, and then a rarefaction wave return from condenser in the evaporator, the boiling in which is resumed and the next cycle of the pulsations is repeated. Numerical simulation was performed using finite element method implemented in the commercial program ANSYS Multiphisics 14.5 in the two-dimensional setting of axis symmetric moist vapour flow with third kind boundary conditions.

Probabilistic Meteorological Characterization for Turbine Loads

DEFF Research Database (Denmark)

Kelly, Mark C.; Larsen, Gunner Chr.; Dimitrov, Nikolay Krasimirov

2014-01-01

Beyond the existing, limited IEC prescription to describe fatigue loads on wind turbines, we look towards probabilistic characterization of the loads via analogous characterization of the atmospheric flow, particularly for today's "taller" turbines with rotors well above the atmospheric surface...

Unscheduled load flow effect due to large variation in the distributed generation in a subtransmission network

Science.gov (United States)

Islam, Mujahidul

A sustainable energy delivery infrastructure implies the safe and reliable accommodation of large scale penetration of renewable sources in the power grid. In this dissertation it is assumed there will be no significant change in the power transmission and distribution structure currently in place; except in the operating strategy and regulatory policy. That is to say, with the same old structure, the path towards unveiling a high penetration of switching power converters in the power system will be challenging. Some of the dimensions of this challenge are power quality degradation, frequent false trips due to power system imbalance, and losses due to a large neutral current. The ultimate result is the reduced life of many power distribution components - transformers, switches and sophisticated loads. Numerous ancillary services are being developed and offered by the utility operators to mitigate these problems. These services will likely raise the system's operational cost, not only from the utility operators' end, but also reflected on the Independent System Operators and by the Regional Transmission Operators (RTO) due to an unforeseen backlash of frequent variation in the load-side generation or distributed generation. The North American transmission grid is an interconnected system similar to a large electrical circuit. This circuit was not planned but designed over 100 years. The natural laws of physics govern the power flow among loads and generators except where control mechanisms are installed. The control mechanism has not matured enough to withstand the high penetration of variable generators at uncontrolled distribution ends. Unlike a radial distribution system, mesh or loop networks can alleviate complex channels for real and reactive power flow. Significant variation in real power injection and absorption on the distribution side can emerge as a bias signal on the routing reactive power in some physical links or channels that are not distinguishable

CFD Analysis of Random Turbulent Flow Load in Steam Generator of APR1400 Under Normal Operation Condition

International Nuclear Information System (INIS)

Lim, Sang Gyu; You, Sung Chang; Kim, Han Gon

2011-01-01

Regulatory guide 1.20 revision 3 of the Nuclear Regulatory Committee (NRC) modifies guidance for vibration assessments of reactor internals and steam generator internals. The new guidance requires applicants to provide a preliminary analysis and evaluation of the design and performance of a facility, including the safety margins of during normal operation and transient conditions anticipated during the life of the facility. Especially, revision 3 require rigorous assessments of adverse flow effects in the steam dryer cased by flow-excited acoustic and structural resonances such as the abnormality from power-uprated BWR cases. For two nearly identical nuclear power plants, the steam system of one BWR plant experienced failure of steam dryers and the main steam system components when steam flow was increased by 16 percent for extended power uprate (EPU). The mechanisms of those failures have revealed that a small adverse flow changing from the prototype condition induced severe flow-excited acoustic and structural resonances, leading to structural failures. In accordance with the historical background, therefore, potential adverse flow effects should be evaluated rigorously for steam generator internals in both BWR and Pressurized Water Reactor (PWR). The Advanced Power Reactor 1400 (APR1400), an evolutionary light water reactor, increased the power by 7.7 percent from the design of the 'Valid Prototype', System80+. Thus, reliable evaluations of potential adverse flow effects on the steam generator of APR1400 are necessary according to the regulatory guide. This paper is part of the computational fluid dynamics (CFD) analysis results for evaluation of the adverse flow effect for the steam generator internals of APR1400, including a series of sensitivity analyses to enhance the reliability of CFD analysis and an estimation the effect of flow loads on the internals of the steam generator under normal operation conditions

Magnetic particle movement program to calculate particle paths in flow and magnetic fields

International Nuclear Information System (INIS)

Inaba, Toru; Sakazume, Taku; Yamashita, Yoshihiro; Matsuoka, Shinya

2014-01-01

We developed an analysis program for predicting the movement of magnetic particles in flow and magnetic fields. This magnetic particle movement simulation was applied to a capturing process in a flow cell and a magnetic separation process in a small vessel of an in-vitro diagnostic system. The distributions of captured magnetic particles on a wall were calculated and compared with experimentally obtained distributions. The calculations involved evaluating not only the drag, pressure gradient, gravity, and magnetic force in a flow field but also the friction force between the particle and the wall, and the calculated particle distributions were in good agreement with the experimental distributions. Friction force was simply modeled as static and kinetic friction forces. The coefficients of friction were determined by comparing the calculated and measured results. This simulation method for solving multiphysics problems is very effective at predicting the movements of magnetic particles and is an excellent tool for studying the design and application of devices. - Highlights: ●We developed magnetic particles movement program in flow and magnetic fields. ●Friction force on wall is simply modeled as static and kinetic friction force. ●This program was applied for capturing and separation of an in-vitro diagnostic system. ●Predicted particle distributions on wall were agreed with experimental ones. ●This method is very effective at predicting movements of magnetic particles

Cost-optimal power system extension under flow-based market coupling

Energy Technology Data Exchange (ETDEWEB)

Hagspiel, Simeon; Jaegemann, Cosima; Lindenberger, Dietmar [Koeln Univ. (Germany). Energiewirtschaftliches Inst.; Brown, Tom; Cherevatskiy, Stanislav; Troester, Eckehard [Energynautics GmbH, Langen (Germany)

2013-05-15

Electricity market models, implemented as dynamic programming problems, have been applied widely to identify possible pathways towards a cost-optimal and low carbon electricity system. However, the joint optimization of generation and transmission remains challenging, mainly due to the fact that different characteristics and rules apply to commercial and physical exchanges of electricity in meshed networks. This paper presents a methodology that allows to optimize power generation and transmission infrastructures jointly through an iterative approach based on power transfer distribution factors (PTDFs). As PTDFs are linear representations of the physical load flow equations, they can be implemented in a linear programming environment suitable for large scale problems. The algorithm iteratively updates PTDFs when grid infrastructures are modified due to cost-optimal extension and thus yields an optimal solution with a consistent representation of physical load flows. The method is first demonstrated on a simplified three-node model where it is found to be robust and convergent. It is then applied to the European power system in order to find its cost-optimal development under the prescription of strongly decreasing CO{sub 2} emissions until 2050.

Electrical load modeling

Energy Technology Data Exchange (ETDEWEB)

Valgas, Helio Moreira; Pinto, Roberto del Giudice R.; Franca, Carlos [Companhia Energetica de Minas Gerais (CEMIG), Belo Horizonte, MG (Brazil); Lambert-Torres, Germano; Silva, Alexandre P. Alves da; Pires, Robson Celso; Costa, Junior, Roberto Affonso [Escola Federal de Engenharia de Itajuba, MG (Brazil)

1994-12-31

Accurate dynamic load models allow more precise calculations of power system controls and stability limits, which are critical mainly in the operation planning of power systems. This paper describes the development of a computer program (software) for static and dynamic load model studies using the measurement approach for the CEMIG system. Two dynamic load model structures are developed and tested. A procedure for applying a set of measured data from an on-line transient recording system to develop load models is described. (author) 6 refs., 17 figs.

Ocean Tide Loading Computation

Science.gov (United States)

Agnew, Duncan Carr

2005-01-01

September 15,2003 through May 15,2005 This grant funds the maintenance, updating, and distribution of programs for computing ocean tide loading, to enable the corrections for such loading to be more widely applied in space- geodetic and gravity measurements. These programs, developed under funding from the CDP and DOSE programs, incorporate the most recent global tidal models developed from Topex/Poscidon data, and also local tide models for regions around North America; the design of the algorithm and software makes it straightforward to combine local and global models.

Application of Newton's optimal power flow in voltage/reactive power control

Energy Technology Data Exchange (ETDEWEB)

Bjelogrlic, M.; Babic, B.S. (Electric Power Board of Serbia, Belgrade (YU)); Calovic, M.S. (Dept. of Electrical Engineering, University of Belgrade, Belgrade (YU)); Ristanovic, P. (Institute Nikola Tesla, Belgrade (YU))

1990-11-01

This paper considers an application of Newton's optimal power flow to the solution of the secondary voltage/reactive power control in transmission networks. An efficient computer program based on the latest achievements in the sparse matrix/vector techniques has been developed for this purpose. It is characterized by good robustness, accuracy and speed. A combined objective function appropriate for various system load levels with suitable constraints, for treatment of the power system security and economy is also proposed. For the real-time voltage/reactive power control, a suboptimal power flow procedure has been derived by using the reduced set of control variables. This procedure is based on the sensitivity theory applied to the determination of zones for the secondary voltage/reactive power control and corresponding reduced set of regulating sources, whose reactive outputs represent control variables in the optimal power flow program. As a result, the optimal power flow program output becomes a schedule to be used by operators in the process of the real-time voltage/reactive power control in both normal and emergency operating states.

CFD-based design load analysis of 5MW offshore wind turbine

Science.gov (United States)

Tran, T. T.; Ryu, G. J.; Kim, Y. H.; Kim, D. H.

2012-11-01

The structure and aerodynamic loads acting on NREL 5MW reference wind turbine blade are calculated and analyzed based on advanced Computational Fluid Dynamics (CFD) and unsteady Blade Element Momentum (BEM). A detailed examination of the six force components has been carried out (three force components and three moment components). Structure load (gravity and inertia load) and aerodynamic load have been obtained by additional structural calculations (CFD or BEM, respectively,). In CFD method, the Reynolds Average Navier-Stokes approach was applied to solve the continuity equation of mass conservation and momentum balance so that the complex flow around wind turbines was modeled. Written in C programming language, a User Defined Function (UDF) code which defines transient velocity profile according to the Extreme Operating Gust condition was compiled into commercial FLUENT package. Furthermore, the unsteady BEM with 3D stall model has also adopted to investigate load components on wind turbine rotor. The present study introduces a comparison between advanced CFD and unsteady BEM for determining load on wind turbine rotor. Results indicate that there are good agreements between both present methods. It is importantly shown that six load components on wind turbine rotor is significant effect under Extreme Operating Gust (EOG) condition. Using advanced CFD and additional structural calculations, this study has succeeded to construct accuracy numerical methodology to estimate total load of wind turbine that compose of aerodynamic load and structure load.

Numerical investigation of the influence of particle-particle and particle-wall collisions in turbulent wall-bounded flows at high mass loadings

International Nuclear Information System (INIS)

Alletto, Michael

2014-01-01

The present work deals with the simulation of turbulent particle-laden flows at high mass loadings. In order to achieve this goal, the fluid flow is described by means of the eddy-resolving concept known as Large-Eddy Simulation (LES) and the particles are described in a Lagrangian frame of reference. Special emphasis is placed on the interparticle collisions and the impact of solid particles on rough walls. Both mechanisms are shown to be crucial for the correct description of the particle dynamics in wall-bounded flows. In order to distinguish the present methodology from the variety of methods available in the literature to treat turbulent flows laden with solid particles, the thesis starts with an overview of different simulation techniques to calculate this class of flows. In this overview special care is taken to underline the parameter space, where the different simulation methods are valid. After that, the governing equations and the boundary conditions applied for the continuous phase of the Euler-Lagrange approach used in the present thesis are given. In the subsequent section the governing equations for the solid particles and their interaction with smooth and rough walls are discussed. Here a new wall roughness model for the particles which incorporates an amplitude parameter used in technical applications such as the mean roughness height or the root-mean-squared roughness is presented. After that, the coupling mechanisms between the phases and the algorithmic realization are discussed. Furthermore, a new agglomeration model capable to treat interparticle collisions with friction is presented. However, the agglomeration model is not evaluated in such a detail as the interparticle collisions and the particle-wall collisions. The reason is that it does not represent a central aspect of this thesis. The numerical methods for the continuous and the disperse phase are presented in the subsequent section. The efficient algorithm to detect the interparticle

Numerical investigation of the influence of particle-particle and particle-wall collisions in turbulent wall-bounded flows at high mass loadings

Energy Technology Data Exchange (ETDEWEB)

Alletto, Michael

2014-05-16

The present work deals with the simulation of turbulent particle-laden flows at high mass loadings. In order to achieve this goal, the fluid flow is described by means of the eddy-resolving concept known as Large-Eddy Simulation (LES) and the particles are described in a Lagrangian frame of reference. Special emphasis is placed on the interparticle collisions and the impact of solid particles on rough walls. Both mechanisms are shown to be crucial for the correct description of the particle dynamics in wall-bounded flows. In order to distinguish the present methodology from the variety of methods available in the literature to treat turbulent flows laden with solid particles, the thesis starts with an overview of different simulation techniques to calculate this class of flows. In this overview special care is taken to underline the parameter space, where the different simulation methods are valid. After that, the governing equations and the boundary conditions applied for the continuous phase of the Euler-Lagrange approach used in the present thesis are given. In the subsequent section the governing equations for the solid particles and their interaction with smooth and rough walls are discussed. Here a new wall roughness model for the particles which incorporates an amplitude parameter used in technical applications such as the mean roughness height or the root-mean-squared roughness is presented. After that, the coupling mechanisms between the phases and the algorithmic realization are discussed. Furthermore, a new agglomeration model capable to treat interparticle collisions with friction is presented. However, the agglomeration model is not evaluated in such a detail as the interparticle collisions and the particle-wall collisions. The reason is that it does not represent a central aspect of this thesis. The numerical methods for the continuous and the disperse phase are presented in the subsequent section. The efficient algorithm to detect the interparticle

Plutonium Immobilization Can Loading Equipment Review

International Nuclear Information System (INIS)

Kriikku, E.; Ward, C.; Stokes, M.; Randall, B.; Steed, J.; Jones, R.; Hamilton, L.

1998-05-01

This report lists the operations required to complete the Can Loading steps on the Pu Immobilization Plant Flow Sheets and evaluates the equipment options to complete each operation. This report recommends the most appropriate equipment to support Plutonium Immobilization Can Loading operations

Limit loads in nozzles

International Nuclear Information System (INIS)

Zouain, N.

1983-01-01

The static method for the evaluation of the limit loads of a perfectly elasto-plastic structure is presented. Using the static theorem of Limit Analysis and the Finite Element Method, a lower bound for the colapso load can be obtained through a linear programming problem. This formulation if then applied to symmetrically loaded shells of revolution and some numerical results of limit loads in nozzles are also presented. (Author) [pt

Comprehensive Forced Response Analysis of J2X Turbine Bladed-Discs with 36- Degree Variation in CFD Loading

Science.gov (United States)

Elrod, David; Christensen, Eric; Brown, Andrew

2011-01-01

At NASA/MSFC, Structural Dynamics personnel continue to perform advanced analysis for the turbomachinery in the J2X Rocket Engine, which is under consideration for the new Space Launch System. One of the most challenging analyses in the program is predicting turbine blade structural capability. Resonance was predicted by modal analysis, so comprehensive forced response analyses using high fidelity cyclic symmetric finite element models were initiated as required. Analysis methodologies up to this point have assumed the flow field could be fully described by a sector, so the loading on every blade would be identical as it travelled through it. However, in the J2X the CFD flow field varied over the 360 deg of a revolution because of the flow speeds and tortuous axial path. MSFC therefore developed a complex procedure using Nastran Dmap's and Matlab scripts to apply this circumferentially varying loading onto the cyclically symmetric structural models to produce accurate dynamic stresses for every blade on the disk. This procedure is coupled with static, spin, and thermal loading to produce high cycle fatigue safety factors resulting in much more accurate analytical assessments of the blades.

1.5 MW RF Load for ITER

International Nuclear Information System (INIS)

Ives, Robert Lawrence; Marsden, David; Collins, George; Karimov, Rasul; Mizuhara, Max; Neilson, Jeffrey

2016-01-01

Calabazas Creek Research, Inc. developed a 1.5 MW RF load for the ITER fusion research facility currently under construction in France. This program leveraged technology developed in two previous SBIR programs that successfully developed high power RF loads for fusion research applications. This program specifically focused on modifications required by revised technical performance, materials, and assembly specification for ITER. This program implemented an innovative approach to actively distribute the RF power inside the load to avoid excessive heating or arcing associated with constructive interference. The new design implemented materials and assembly changes required to meet specifications. Critical components were built and successfully tested during the program.

1.5 MW RF Load for ITER

Energy Technology Data Exchange (ETDEWEB)

Ives, Robert Lawrence [Calabazas Creek Research, Inc., San Mateo, CA (United States); Marsden, David [Calabazas Creek Research, Inc., San Mateo, CA (United States); Collins, George [Calabazas Creek Research, Inc., San Mateo, CA (United States); Karimov, Rasul [Calabazas Creek Research, Inc., San Mateo, CA (United States); Mizuhara, Max [Calabazas Creek Research, Inc., San Mateo, CA (United States); Neilson, Jeffrey [Lexam Research, Redwood City, CA (United States)

2016-09-01

Calabazas Creek Research, Inc. developed a 1.5 MW RF load for the ITER fusion research facility currently under construction in France. This program leveraged technology developed in two previous SBIR programs that successfully developed high power RF loads for fusion research applications. This program specifically focused on modifications required by revised technical performance, materials, and assembly specification for ITER. This program implemented an innovative approach to actively distribute the RF power inside the load to avoid excessive heating or arcing associated with constructive interference. The new design implemented materials and assembly changes required to meet specifications. Critical components were built and successfully tested during the program.

Proppant backflow: Mechanical and flow considerations

Energy Technology Data Exchange (ETDEWEB)

McLennan, John [Univ. of Utah, Salt Lake City, UT (United States); Walton, Ian [Univ. of Utah, Salt Lake City, UT (United States); Moore, Joseph [Univ. of Utah, Salt Lake City, UT (United States); Brinton, Dan [Univ. of Utah, Salt Lake City, UT (United States); Lund, Jeff [TerraTek Inc., Salt Lake City, UT (United States)

2015-09-01

One of the concerns of using proppant in geothermal wells, and particularly in enhanced geothermal systems, is proppant flowback. Particulate proppant maintain post-closure conductivity in hydraulically opened fractures. If that proppant is displaced from the near-wellbore region, either due to overflushing during stimulation or flowback to the wellbore at any time, the reduced fracture width chokes the injection or production. Two intermediate-scale laboratory analogs of a propped hydraulic fracture were prepared, and fluid was flowed through a normally stressed, propped fracture into a central wellbore. The tests were conducted in a polyaxial load frame. Acoustic/microseismic activity was measured during the injection programs. In one scenario—radial flow through a transverse fracture to a wellbore—the results suggest the creation of flow channels and nominally intact propped zones around the channels, maintaining fracture aperture. In the other—linear flow through a longitudinal fracture into a wellbore—there was substantially more proppant removal. The measurements have shown a greater tendency for proppant flowback in a linear flow situation (proppant movement is kinematically more restricted for radial convergent flow). The pressure gradients causing flow are exceedingly small and restraining flowback will be difficult. Convergent flow relationships could be an issue for injector wells, which will experience fluid flowback during hard shutdowns.

Liquid loading experiments with tube wall modifications

NARCIS (Netherlands)

Belfroid, S.P.C.; Schiferli, W.; Veltin, J.; Veeken, K.

2011-01-01

This paper discusses the multiphase flow mechanism responsible for gas-well liquid loading. It demonstrates that the conventional idea of droplet flow reversal (Turner et al. (1)) does not capture reality and that actual observations are better described by film flow reversal phenomenon. The

Modelling the work flow of a nuclear waste management program

Energy Technology Data Exchange (ETDEWEB)

Hoeyer Mortensen, K. [Aarhus Univ., Computer Science Dept. (Denmark); Pinci, V. [Meta Software Corporation, Cambridge, MA (United States)

1997-03-01

In this paper we describe a modelling project to improve a nuclear waste management program in charge of the creation of a new system for the permanent disposal of nuclear waste. SADT (Structural Analysis and Design Technique) is used in order to provide a work-flow description of the functions to be performed by the waste management program. This description is then translated into a number of Coloured Petri Nets (CPN or CP-nets) corresponding to different program functions where additional behavioural inscriptions provide basis for simulation. Each of these CP-nets is simulated to produce timed event charts that are useful for understanding the behaviour of the program functions under different scenarios. Then all the CPN models are linked together to form a single stand-alone application that is useful for validating the interaction and cooperation between the different program functions. A technique for linking executable CPN models is developed for supporting large modelling projects and parallel development of independent CPN models. (au) 11 refs.

Modelling the work flow of a nuclear waste management program

International Nuclear Information System (INIS)

Hoeyer Mortensen, K.; Pinci, V.

1997-03-01

In this paper we describe a modelling project to improve a nuclear waste management program in charge of the creation of a new system for the permanent disposal of nuclear waste. SADT (Structural Analysis and Design Technique) is used in order to provide a work-flow description of the functions to be performed by the waste management program. This description is then translated into a number of Coloured Petri Nets (CPN or CP-nets) corresponding to different program functions where additional behavioural inscriptions provide basis for simulation. Each of these CP-nets is simulated to produce timed event charts that are useful for understanding the behaviour of the program functions under different scenarios. Then all the CPN models are linked together to form a single stand-alone application that is useful for validating the interaction and cooperation between the different program functions. A technique for linking executable CPN models is developed for supporting large modelling projects and parallel development of independent CPN models. (au) 11 refs

A Bayesian changepoint-threshold model to examine the effect of TMDL implementation on the flow-nitrogen concentration relationship in the Neuse River basin.

Science.gov (United States)

Alameddine, Ibrahim; Qian, Song S; Reckhow, Kenneth H

2011-01-01

In-stream nutrient concentrations are well known to exhibit a strong relationship with river flow. The use of flow measurements to predict nutrient concentrations and subsequently nutrient loads is common in water quality modeling. Nevertheless, most adopted models assume that the relationship between flow and concentration is fixed across time as well as across different flow regimes. In this study, we developed a Bayesian changepoint-threshold model that relaxes these constraints and allows for the identification and quantification of any changes in the underlying flow-concentration relationship across time. The results from our study support the occurrence of a changepoint in time around the year 1999, which coincided with the period of implementing nitrogen control measures as part of the TMDL program developed for the Neuse Estuary in North Carolina. The occurrence of the changepoint challenges the underlying assumption of temporal invariance in the flow-concentrations relationship. The model results also point towards a transition in the river nitrogen delivery system from a point source dominated loading system towards a more complicated nonlinear system, where non-point source nutrient delivery plays a major role. Moreover, we use the developed model to assess the effectiveness of the nitrogen reduction measures in achieving a 30% drop in loading. The results indicate that while there is a strong evidence of a load reduction, there still remains a high level of uncertainty associated with the mean nitrogen load reduction. We show that the level of uncertainty around the estimated load reduction is not random but is flow related. Copyright © 2010 Elsevier Ltd. All rights reserved.

Light Water Breeder Reactor (LWBR) flow coefficient of reactivity: (LWBR Development Program)

International Nuclear Information System (INIS)

Sarber, W.K.; Stout, J.W.; Atherton, R.

1987-06-01

This report discusses the results of an experimental program to measure and categorize the causes for increases in the magnitude of the LWBR flow coefficient of reactivity at 10,932 EFPH from previously measured near zero values to a value of about 6 x 10 -4 Δ rho for a flow decrease from 100 to 80% of full flow. Reactor protection analyses confirmed that existing protection systems were adequate for continued operation. Subsequently, the flow coefficient decreased in magnitude to approximately 2.25 x 10 -4 Δ rho at 20,000 EFPH and remained about constant through the remainder of core life, 29,047 EFPH. The increase in flow coefficient of reactivity is attributed to a flow-force dependent change in the effective core diameter such that an increase in core flow decreased the core diameter, resulting in an increase in fuel-to-water ratio and a consequent decrease in the reactivity of this relatively undermoderated core. This report discusses why the increased flow coefficient did not occur until after 10,932 EFPH and why the magnitude of flow coefficient reduced with continued core operation

Subchannel analysis program for boiling water reactor fuel bundles based on five conservation equations of two-phase flow

International Nuclear Information System (INIS)

Bessho, Y.; Uchikawa, S.

1985-01-01

A subchannel analysis program, MENUETT, is developed for evaluation of thermal-hydraulic characteristics in boiling water reactor fuel bundles. This program is based on five conservation equations of two-phase flow with the drift-flux correlation. The cross flows are calculated separately for liquid and vapor phases from the lateral momentum conservation equation. The effects of turbulent mixing and void drift are accounted for in the program. The conservation equations are implicitly differentiated with the convective terms by the donor-cell method, and are solved iteratively in the axial and lateral directions. Data of the 3 X 3 rod bundle experiments are used for program verification. The lateral distributions of equilibrium quality and mass flow rate at the bundle exit calculated by the program compare satisfactorily with the experimental results

Renewable Distributed Generation Models in Three-Phase Load Flow Analysis for Smart Grid

Directory of Open Access Journals (Sweden)

K. M. Nor

2013-11-01

Full Text Available The paper presents renewable distributed generation  (RDG models as three-phase resource in load flow computation and analyzes their effect when they are connected in composite networks. The RDG models that have been considered comprise of photovoltaic (PV and wind turbine generation (WTG. The voltage-controlled node and complex power injection node are used in the models. These improvement models are suitable for smart grid power system analysis. The combination of IEEE transmission and distribution data used to test and analyze the algorithm in solving balanced/unbalanced active systems. The combination of IEEE transmission data and IEEE test feeder are used to test the the algorithm for balanced and unbalanced multi-phase distribution system problem. The simulation results show that by increased number and size of RDG units have improved voltage profile and reduced system losses.

Sample intake position and loading rates from nonpoint source pollution

Science.gov (United States)

McGuire, P. E.; Daniel, T. C.; Stoffel, D.; Andraski, B.

1980-01-01

Paired water samples were simultaneously activated from two different vertical positions within the approach section of a flow-control structure to determine the effect of sample intake position on nonpoint runoff parameter concentrations and subsequent event loads. Suspended solids (SS), total phosphorus (TP) and organic plus exchangeable nitrogen [(Or+Ex)-N] were consistently higher throughout each runoff event when sampled from the floor of the approach section as opposed to those samples taken at midstage. Dissolved molybdate reactive phosphorus (DMRP) and ammonium (NH4-N) concentrations did not appear to be significantly affected by the vertical difference in intake position. However, the nitrate plus nitrite nitrogen [(NO3+NO2)-N] concentrations were much higher when sampled from the midstage position. Although the concentration differences between the two methods were not appreciable, when evaluated in terms of event loads, discrepancies were evident for all parameters. Midstage sampling produced event loads for SS, TP, (Or + Ex)-N, DMRP, NH4-N, and (NO3+NO2)-N that were 44,39,35,80,71, and 181%, respectively, of floor sampling loads. Differences in loads between the two methods are attributed to the midstage position, sampling less of the bed load. The correct position will depend on the objective; however, such differences should be recognized during the design phase of the monitoring program.

Dynamic load balance scheme for the DSMC algorithm

International Nuclear Information System (INIS)

Li, Jin; Geng, Xiangren; Jiang, Dingwu; Chen, Jianqiang

2014-01-01

The direct simulation Monte Carlo (DSMC) algorithm, devised by Bird, has been used over a wide range of various rarified flow problems in the past 40 years. While the DSMC is suitable for the parallel implementation on powerful multi-processor architecture, it also introduces a large load imbalance across the processor array, even for small examples. The load imposed on a processor by a DSMC calculation is determined to a large extent by the total of simulator particles upon it. Since most flows are impulsively started with initial distribution of particles which is surely quite different from the steady state, the total of simulator particles will change dramatically. The load balance based upon an initial distribution of particles will break down as the steady state of flow is reached. The load imbalance and huge computational cost of DSMC has limited its application to rarefied or simple transitional flows. In this paper, by taking advantage of METIS, a software for partitioning unstructured graphs, and taking the total of simulator particles in each cell as a weight information, the repartitioning based upon the principle that each processor handles approximately the equal total of simulator particles has been achieved. The computation must pause several times to renew the total of simulator particles in each processor and repartition the whole domain again. Thus the load balance across the processors array holds in the duration of computation. The parallel efficiency can be improved effectively. The benchmark solution of a cylinder submerged in hypersonic flow has been simulated numerically. Besides, hypersonic flow past around a complex wing-body configuration has also been simulated. The results have displayed that, for both of cases, the computational time can be reduced by about 50%

Design and implementation of an external quality assessment program for HIV viral load measurements using dried blood spots.

Science.gov (United States)

Prach, Lisa M; Puren, Adrian; Lippman, Sheri A; Carmona, Sergio; Stephenson, Sophie; Cutler, Ewalde; Barnhart, Scott; Liegler, Teri

2015-03-01

An external quality assurance program was developed for HIV-1 RNA viral load measurements taken from dried blood spots using a reference panel and field-collected specimens. The program demonstrated that accurate and reproducible quantitation can be obtained from field-collected specimens. Residual proviral DNA may confound interpretation in virologically suppressed subjects. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Airfoil flow instabilities induced by background flow oscillations

Energy Technology Data Exchange (ETDEWEB)

Selerowicz, W.C.; Szumowski, A.P. [Technical Univ. Warsaw (Poland)

2002-04-01

The effect of background flow oscillations on transonic airfoil (NACA 0012) flow was investigated experimentally. The oscillations were generated by means of a rotating plate placed downstream of the airfoil. Owing to oscillating chocking of the flow caused by the plate, the airfoil flow periodically accelerated and decelerated. This led to strong variations in the surface pressure and the airfoil loading. The results are presented for two angles of attack, {alpha}=4 and {alpha}=8.5 , which correspond to the attached and separated steady airfoil flows, respectively. (orig.)

Effect of cyclic loading on the viscoplastic behaviour of Zircaloy 4 cladding tubes

International Nuclear Information System (INIS)

Bouffioux, P.; Gabriel, B.; Soniak, A.; Mardon, J.P.

1995-06-01

Most of the electricity being generated by nuclear energy load follow and remote control have become normal operating modes in the French PWR. In addition, EDF is developing a strategy of fuel sub-assembly burnup extension. Those operating conditions will lead to cyclic straining of the Zircaloy cladding tube which could induce damages. Therefore, EDF, CEA, and FRAMATOME has started a joint R and D cooperative program in order to investigate the mechanical behaviour of Zircaloy cladding tubes under cyclic loading. This paper is dealing with the effect of a pre-cyclic loading on the plasticity properties of Zircaloy 4 cladding tubes. Load controlled cyclic tests were carried out at 350 deg. C and 0.5 Hz in both axial and hoop directions. The Woehler curves were determined. Sequential tests combining pre-cyclic loading to 50 and 75 % fraction life with tension were then performed. It has ben noticed that the pre-cycling loading does not change the plastic flow curve of the Zircaloy 4 cladding tubes and therefore does not induce observable macroscopic damage. It has been concluded that a linear cumulative damage rule like ΣΔN(σ)/N r(σ) is very conservative. (author)

Analysis of the interaction between a submerged jet and a receiver-diffuser in a reverse-flow diverter. Consolidated Fuel Reprocessing Program

International Nuclear Information System (INIS)

Smith, G.V.; Counce, R.M.

1983-01-01

Two mathematical models of the interaction between a submerged jet emanating from the nozzle of a reverse flow diverter (RFD) and a receiver-diffuser of a venturi-like reverse flow diverter are presented and compared with experimental data. Both models predict the output characteristics fairly accurately, although the experimentally measured flow is observed to saturate at higher values of jet dynamic pressure and at lower values of output load impedances. An analysis based on the inviscid flow model indicates cavitation as the likely cause of the flow saturation

Scheduling of radio-controlled heating load

International Nuclear Information System (INIS)

Fox, B.; McCartney, A.I.; McCann, B.M.

1998-01-01

An economic loading program has been adapted to enable it to obtain an optimum heat-load profile to meet the forecast heat requirement. The heat load is represented by a 'generator' whose load is constrained to be negative. The incremental cost of this unit is a heat energy price. This is adjusted to obtain a heat profile containing the requisite energy. The profile is then used by a dynamic programming algorithm to derive a commitment pattern for each block. A case study is presented which shows that the procedure can minimise heat energy cost. It is also shown that use of the proposed method results in less generator load cycling. This reduced regulation duty should improve reliability. (author)

Diffusion and bulk flow in phloem loading

DEFF Research Database (Denmark)

Dölger, Julia; Rademaker, Hanna; Liesche, Johannes

2014-01-01

Plants create sugar in the mesophyll cells of their leaves by photosynthesis. This sugar, mostly sucrose, has to be loaded via the bundle sheath into the phloem vascular system (the sieve elements), where it is distributed to growing parts of the plant. We analyze the feasibility of a particular...

Program determines two-phase flow

International Nuclear Information System (INIS)

Yamashiro, C.E.; Espiell, L.G.S.; Farina, I.H.

1986-01-01

When a mixture of a gas and a liquid flows along a horizontal pipe, it is possible to have up to seven different flow patterns. These flow patterns are: 1. Dispersed. When nearly all the liquid is entrained as spray by the gas; 2. Annular. The liquid forms a film around the inside wall of the pipe, and the gas flows at a high velocity as a central core; 3. Bubble. Bubbles of gas move along at about the same velocity as the liquid; 4. Stratified. The liquid flows along the bottom of the pipe and the gas flows above over a smooth gas-liquid interface; 5. Wave. Is similar to stratified except the interface is disturbed by waves moving in the direction of flow; 6. Slug. Waves are picked up periodically in the form of frothy slugs that move at a much greater velocity than the average liquid velocity; 7. Plug. Alternate plugs of liquid and gas move along the pipe

Nonstationary heat flow in the piston of the turbocharged engine

Directory of Open Access Journals (Sweden)

Piotr GUSTOF

2010-01-01

Full Text Available In this study the numeric computations of nonstationary heat flow in form of temperature distribution on characteristic surfaces of the piston of the turbocharged engine at the beginning phase its work was presented. The computations were performed for fragmentary load engine by means of the two-zone combustion model, the boundary conditions of III kind and the finite elements method (FEM by using of COSMOS/M program.

Development of a VVER-1000 core loading pattern optimization program based on perturbation theory

International Nuclear Information System (INIS)

Hosseini, Mohammad; Vosoughi, Naser

2012-01-01

Highlights: ► We use perturbation theory to find an optimum fuel loading pattern in a VVER-1000. ► We provide a software for in-core fuel management optimization. ► We consider two objectives for our method (perturbation theory). ► We show that perturbation theory method is very fast and accurate for optimization. - Abstract: In-core nuclear fuel management is one of the most important concerns in the design of nuclear reactors. Two main goals in core fuel loading pattern design optimization are maximizing the core effective multiplication factor in order to extract the maximum energy, and keeping the local power peaking factor lower than a predetermined value to maintain the fuel integrity. Because of the numerous possible patterns of fuel assemblies in the reactor core, finding the best configuration is so important and challenging. Different techniques for optimization of fuel loading pattern in the reactor core have been introduced by now. In this study, a software is programmed in C language to find an order of the fuel loading pattern of a VVER-1000 reactor core using the perturbation theory. Our optimization method is based on minimizing the radial power peaking factor. The optimization process launches by considering an initial loading pattern and the specifications of the fuel assemblies which are given as the input of the software. The results on a typical VVER-1000 reactor reveal that the method could reach to a pattern with an allowed radial power peaking factor and increases the cycle length 1.1 days, as well.

Identifying the Correlation between Water Quality Data and LOADEST Model Behavior in Annual Sediment Load Estimations

Directory of Open Access Journals (Sweden)

Youn Shik Park

2016-08-01

Full Text Available Water quality samples are typically collected less frequently than flow since water quality sampling is costly. Load Estimator (LOADEST, provided by the United States Geological Survey, is used to predict water quality concentration (or load on days when flow data are measured so that the water quality data are sufficient for annual pollutant load estimation. However, there is a need to identify water quality data requirements for accurate pollutant load estimation. Measured daily sediment data were collected from 211 streams. Estimated annual sediment loads from LOADEST and subsampled data were compared to the measured annual sediment loads (true load. The means of flow for calibration data were correlated to model behavior. A regression equation was developed to compute the required mean of flow in calibration data to best calibrate the LOADEST regression model coefficients. LOADEST runs were performed to investigate the correlation between the mean flow in calibration data and model behaviors as daily water quality data were subsampled. LOADEST calibration data used sediment concentration data for flows suggested by the regression equation. Using the mean flow calibrated by the regression equation reduced errors in annual sediment load estimation from −39.7% to −10.8% compared to using all available data.

Inductive-energy power flow for X-ray sources

Energy Technology Data Exchange (ETDEWEB)

Ware, K D; Filios, P G; Gullickson, R L; Hebert, M P; Rowley, J E; Schneider, R F; Summa, W J [Defense Nuclear Agency, Alexandria, VA (United States); Vitkovski, I M [Logicon RDA, Arlington, VA (United States)

1997-12-31

The Defense Nuclear Agency (DNA) has been developing inductive energy storage (IES) technology for generating intense x-rays from electron beam-target interactions and from plasma radiating sources (PRS). Because of the complex interaction between the commutation of the current from the plasma and the stable dissipation of the energy in the load, DNA has supported several variations of power flow technology. Major variations include: (1) current interruption using a plasma opening switch (POS); (2) continuous current commutation through current-plasma motion against neutral, ionized, or magnetized medium [i.e., dense plasma focus-like (DPF) and plasma flow switch (PFS) technologies]; and, in addition, possible benefits of (3) directly driven complex PRS loads are being investigated. DNA programs include experimental and theoretical modeling and analysis with investigations (1) on Hawk and a Decade module in conjunction with the development of the bremsstrahlung sources (BRS), and (2) on Hawk, ACE-4 and Shiva-Star, as well as cooperative research on GIT-4 and GIT-8, in conjunction with PRS. (author). 1 tab., 12 figs., 17 refs.

Inductive-energy power flow for X-ray sources

International Nuclear Information System (INIS)

Ware, K.D.; Filios, P.G.; Gullickson, R.L.; Hebert, M.P.; Rowley, J.E.; Schneider, R.F.; Summa, W.J.; Vitkovski, I.M.

1996-01-01

The Defense Nuclear Agency (DNA) has been developing inductive energy storage (IES) technology for generating intense x-rays from electron beam-target interactions and from plasma radiating sources (PRS). Because of the complex interaction between the commutation of the current from the plasma and the stable dissipation of the energy in the load, DNA has supported several variations of power flow technology. Major variations include: (1) current interruption using a plasma opening switch (POS); (2) continuous current commutation through current-plasma motion against neutral, ionized, or magnetized medium [i.e., dense plasma focus-like (DPF) and plasma flow switch (PFS) technologies]; and, in addition, possible benefits of (3) directly driven complex PRS loads are being investigated. DNA programs include experimental and theoretical modeling and analysis with investigations (1) on Hawk and a Decade module in conjunction with the development of the bremsstrahlung sources (BRS), and (2) on Hawk, ACE-4 and Shiva-Star, as well as cooperative research on GIT-4 and GIT-8, in conjunction with PRS. (author). 1 tab., 12 figs., 17 refs

Sediment and Fecal Indicator Bacteria Loading in a Mixed Land Use Watershed: Contributions from Suspended and Bed Load Transport

Science.gov (United States)

Water quality studies that quantify sediment and fecal bacteria loading commonly focus on suspended contaminants transported during high flows. Fecal contaminants in bed sediments are typically ignored and need to be considered because of their potential to increase pathogen load...

Spatial Variation of Phosphorous Retention Capacity in Subsurface Flow Constructed Wetlands: Effect of Wetland Type and Inflow Loading.

Directory of Open Access Journals (Sweden)

Guangwei Yu

Full Text Available For verification of spatial distribution of phosphorous retention capacity in constructed wetlands systems(CWs, two horizontal subsurface flow(HSSF CWs and two vertical subsurface flow(VSSF CWs, using sand as substrate and Typha latifolia as wetland plants, were constructed and put into use for synthetic wastewater treatment. Five months later, significant spatial variations of TP and inorganic phosphorus(Ca-P, Fe-P and Al-P were observed, which were found to be greatly affected by CWs type and hydraulic loading. The results revealed that though spatial distribution of Fe-P and Al-P displayed a similar order of substrate content as "rhizosphere" > "near-rhizosphere" > "non-rhizosphere" and "inflow section" > "outflow section" regardless of types and loading, the distribution of Ca-P was positively correlated to that of Fe-P and Al-P in HSSF CWs, while negative correlation was shown in VSSF CWs. As a result, TP spatial distribution in HSSF CWs demonstrated a greater dissimilarity than that in VSSF CWs. For HSSF CWs with low hydraulic loading, the lowest TP content was found in non-rhizosphere substrate of outflow section, while the highest one was discovered in rhizonsphere substrate of inflow section. The values in 6 parts of areas ranged from 0.138 g·kg-1 to 2.710 g·kg-1, which also were from -33.5% to 1209% compared to the control value. On contrast, spatial difference of TP content in substrates of VSSF CWs was insignificant, with a variation ranging from 0.776 g·kg-1 to 1.080 g·kg-1, that was 275% to 421% higher than the control value. In addition, when hydraulic loading was increased, TP content in VSSF CWs sharply decreased, ranging from 0.210 g·kg-1 to 0.634 g·kg-1. Meanwhile, dissimilarity of TP spatial distribution in HSSF CWs was reduced, with TP content ranging from 0.258 g·kg-1 to 2.237 g·kg-1. The results suggested that P spatial distribution should be taken into account for CWs design and operation.

Greywater pollution variability and loadings

DEFF Research Database (Denmark)

Eriksson, Eva; Andersen, Henrik Rasmus; Madsen, Toke S.

2009-01-01

Small on-site greywater treatment and reuse plants are susceptible to high short-term variation in flow and pollutant concentrations. As demonstrated in this study of a bathroom greywater plant in Copenhagen, Denmark, the flow ranges from no-flow periods to high-flow periods reaching 34 l min−1...... per day, whereas the paraben loadings were below 1 mg per person per day. These data are highly relevant for comparing decentralised treatment options with existing end-of-pipe treatments, for feeding into risk assessments and for design purposes....

Calculations of slurry pump jet impingement loads

International Nuclear Information System (INIS)

Wu, T.T.

1996-01-01

This paper presents a methodology to calculate the impingement load in the region of a submerged turbulent jet where a potential core exits and the jet is not fully developed. The profile of the jet flow velocities is represented by a piece-wise linear function which satisfies the conservation of momentum flux of the jet flow. The adequacy of the of the predicted jet expansion is further verified by considering the continuity of the jet flow from the region of potential core to the fully developed region. The jet impingement load can be calculated either as a direct impingement force or a drag force using the jet velocity field determined by the methodology presented

A Mechanism for Stratifying Lava Flows

Science.gov (United States)

Rice, A.

2005-12-01

Relict lava flows (e.g., komatiites) are often reported to be zoned in the vertical, each zone separated by a sharp contact. Such stratifications in igneous flows, both intrusive and extrusive, can be treated as analogues of suspended loads of sediments in rivers and streams, and hence amenable to quantitative treatment derived for the hydraulic environment as long as dynamic similitude is assured. Situations typically encountered in the hydraulic environment are streams carrying a bed load at the bottom of the stream, the bed load separated by a sharp horizon from a sediment load carried above it. This sediment load may be topped by others of decreasing density as one moves to the surface of the flow, with perhaps the uppermost layer clear of any suspended matter. Rules exist for estimating the thickness D of these loads: one of them is given by D ~ 4.4V3/rgcvs where V is the shear velocity or average velocity of the flow, r = (ρs - ρl)/ρl where ρs is the density of the suspended solid matter, ρl the density of the fluid, g the acceleration of gravity, c the concentration of the particulate content and vs the settling velocity. The settling velocity is secured through Stoke's Law and the velocity of the flow is given by V = R2/3S1/2/n where R is the hydraulic radius, S the gradient along which the fluid flows and n is the Manning Coefficient. In the igneous case, the bed load would be composed of primocrysts, i.e., of the first crystals to come out of solution as the flow cools along its run. This would leave the upper portions of the flow more evolved except perhaps for a quenched crust riding atop the flow. As the viscosity of the flow is dependent not only on temperature but on composition and crystal content, the mean velocity of each layer will be different from the layer above and below it. This requires shear at the interface of adjoining stratifications, which brings into play another mechanism: dispersive pressure (the Bagnold effect). Dispersive

Scalable control program for multiprecursor flow-type atomic layer deposition system

Energy Technology Data Exchange (ETDEWEB)

Selvaraj, Sathees Kannan [Department of Chemical Engineering, University of Illinois at Chicago, Chicago, Illinois 60607 (United States); Takoudis, Christos G., E-mail: takoudis@uic.edu [Department of Chemical Engineering, University of Illinois at Chicago, Chicago, Illinois 60607 and Department of Bioengineering, University of Illinois at Chicago, Chicago, Illinois 60607 (United States)

2015-01-01

The authors report the development and implementation of a scalable control program to control flow type atomic layer deposition (ALD) reactor with multiple precursor delivery lines. The program logic is written and tested in LABVIEW environment to control ALD reactor with four precursor delivery lines to deposit up to four layers of different materials in cyclic manner. The programming logic is conceived such that to facilitate scale up for depositing more layers with multiple precursors and scale down for using single layer with any one precursor in the ALD reactor. The program takes precursor and oxidizer exposure and purging times as input and controls the sequential opening and closing of the valves to facilitate the complex ALD process in cyclic manner. The program could be used to deposit materials from any single line or in tandem with other lines in any combination and in any sequence.

Computer program for the analysis of the cross flow in a radial inflow turbine scroll

Science.gov (United States)

Hamed, A.; Abdallah, S.; Tabakoff, W.

1977-01-01

A computer program was used to solve the governing of the potential flow in the cross sectional planes of a radial inflow turbine scroll. A list of the main program, the subroutines, and typical output example are included.

Software defined network architecture based research on load balancing strategy

Science.gov (United States)

You, Xiaoqian; Wu, Yang

2018-05-01

As a new type network architecture, software defined network has the key idea of separating the control place of the network from the transmission plane, to manage and control the network in a concentrated way; in addition, the network interface is opened on the control layer and the data layer, so as to achieve programmable control of the network. Considering that only the single shortest route is taken into the calculation of traditional network data flow transmission, and congestion and resource consumption caused by excessive load of link circuits are ignored, a link circuit load based flow media business QoS gurantee system is proposed in this article to divide the flow in the network into ordinary data flow and QoS flow. In this way, it supervises the link circuit load with the controller so as to calculate reasonable route rapidly and issue the flow table to the exchanger, to finish rapid data transmission. In addition, it establishes a simulation platform to acquire optimized result through simulation experiment.

Significant ELCAP analysis results: Summary report. [End-use Load and Consumer Assessment Program

Energy Technology Data Exchange (ETDEWEB)

Pratt, R.G.; Conner, C.C.; Drost, M.K.; Miller, N.E.; Cooke, B.A.; Halverson, M.A.; Lebaron, B.A.; Lucas, R.G.; Jo, J.; Richman, E.E.; Sandusky, W.F. (Pacific Northwest Lab., Richland, WA (USA)); Ritland, K.G. (Ritland Associates, Seattle, WA (USA)); Taylor, M.E. (USDOE Bonneville Power Administration, Portland, OR (USA)); Hauser, S.G. (Solar Energy Research Inst., Golden, CO (USA))

1991-02-01

The evolution of the End-Use Load and Consumer Assessment Program (ELCAP) since 1983 at Bonneville Power Administration (Bonneville) has been eventful and somewhat tortuous. The birth pangs of a data set so large and encompassing as this have been overwhelming at times. The early adolescent stage of data set development and use has now been reached and preliminary results of early analyses of the data are becoming well known. However, the full maturity of the data set and the corresponding wealth of analytic insights are not fully realized. This document is in some sense a milestone in the brief history of the program. It is a summary of the results of the first five years of the program, principally containing excerpts from a number of previous reports. It is meant to highlight significant accomplishments and analytical results, with a focus on the principal results. Many of the results have a broad application in the utility load research community in general, although the real breadth of the data set remains largely unexplored. The first section of the document introduces the data set: how the buildings were selected, how the metering equipment was installed, and how the data set has been prepared for analysis. Each of the sections that follow the introduction summarize a particular analytic result. A large majority of the analyses to date involve the residential samples, as these were installed first and had highest priority on the analytic agenda. Two exploratory analyses using commercial data are included as an introduction to the commercial analyses that are currently underway. Most of the sections reference more complete technical reports which the reader should refer to for details of the methodology and for more complete discussion of the results. Sections have been processed separately for inclusion on the data base.

The established mega watt linear programming-based optimal power flow model applied to the real power 56-bus system in eastern province of Saudi Arabia

International Nuclear Information System (INIS)

Al-Muhawesh, Tareq A.; Qamber, Isa S.

2008-01-01

A current trend in electric power industries is the deregulation around the world. One of the questions arise during any deregulation process is: where will be the future generation expansion? In the present paper, the study is concentrated on the wheeling computational method as a part of mega watt (MW) linear programming-based optimal power flow (LP-based OPF) method. To observe the effects of power wheeling on the power system operations, the paper uses linear interactive and discrete optimizer (LINDO) optimizer software as a powerful tool for solving linear programming problems to evaluate the influence of the power wheeling. As well, the paper uses the optimization tool to solve the economic generation dispatch and transmission management problems. The transmission line flow was taken in consideration with some constraints discussed in this paper. The complete linear model of the MW LP-based OPF, which is used to know the future generation potential areas in any utility is proposed. The paper also explains the available economic load dispatch (ELD) as the basic optimization tool to dispatch the power system. It can be concluded in the present study that accuracy is expensive in terms of money and time and in the competitive market enough accuracy is needed without paying much

Study of turbulent flows loaded with particles. Application to the particulate fouling of corrugated plate heat exchangers

International Nuclear Information System (INIS)

Kouidri, Frederic

1997-01-01

This work is a numerical and experimental study of the behaviour of a turbulent flow loaded with solid particles. It involves the particulate fouling of plate heat exchangers used in industrial field. Visual observation and LDA measurements inside a mock-up show the presence of large coherent vortices and confirm the tight link between particulate deposition and flow field. The vortices participate to the creation of preferential areas where the particles are in contact with the wall, and they shape the deposit according to a precise mechanism. Two processes of deposit removal have also been shown. Hydraulic phenomena and particles behaviours pointed out in the experiment are compared to different typical samples in a bibliographic survey. The use of the a software for computational fluid dynamics (TRIO developed at the Commissariat a l'Energie Atomique) completed the experimental results by predicting the particles behaviour into the turbulent flow. The approach is based on a connection between a pseudo-direct simulation of the turbulent flow and a Lagrangian model for particles paths. The results show good agreements, qualitatively speaking, between numerical predictions and experimental measurement. The arrangement of the deposit onto the corrugated surface is globally well described by numerical simulation. The influence of some parameters on deposition process such as the flow (corresponding to Re=5000 or Re=10000), the horizontal or vertical position of the channel or the particles diameter (d p =100 μm or d p =25 μm) has been studied. (author) [fr

Analysis of the Mannshan Unit 2 full load rejection transient

International Nuclear Information System (INIS)

Kang, J.C.; Pei, B.S.; Yu, G.P.; Yuann, R.Y.

1987-01-01

Mannshan Unit 2 is a Westinghouse three-loop pressurized water reactor with a rated core power of 2775 MW(thermal) and a rated core flow of 4702 kg/s. Before full power operation, a planned net load rejection was performed during the startup test by opening the main transformer highside breakers. The generator power rapidly reduced to station load. All 16 steam dump valves immediately popped open, and control bank-D rods automatically stepped in as the temperature difference T/sub avg/ - T/sub ref/ reached a programmed 2.8 0 C. Nuclear power decreased smoothly as control rods were inserted into the core. The pressurizer pressure and liquid levels also dropped. Neither safety injection nor reactor trip occurred during this transient. The test was done to verify that the whole system would function properly under a transient to keep the reactor from scramming and that the vessel integrity would also be protected. In this study, which is the preliminary stage of RELAP5/MOD2 transient simulation of the Mannshan PWR plants, system thermal-hydraulic response is tested first and isolated from the neutronic effects. The variation of core power versus time curve was extracted from the power test data to serve as a time varying boundary condition. The comparison of the analytical results of four major parameters (pressurizer pressure, average temperature of the core, steam dump flow rate, and feedwater flow rate) from RELAP5/MOD2 and the power test data is illustrated

Effect of engine load and biogas flow rate to the performance of a compression ignition engine run in dual-fuel (dieselbiogas) mode

Science.gov (United States)

Ambarita, H.

2018-02-01

The Government of Indonesia (GoI) has released a target on reduction Green Houses Gases emissions (GHG) by 26% from level business-as-usual by 2020, and the target can be up to 41% by international supports. In the energy sector, this target can be reached effectively by promoting fossil fuel replacement or blending with biofuel. One of the potential solutions is operating compression ignition (CI) engine in dual-fuel (diesel-biogas) mode. In this study effects of engine load and biogas flow rate on the performance and exhaust gas emissions of a compression ignition engine run in dual-fuel mode are investigated. In the present study, the used biogas is refined with methane content 70% of volume. The objectives are to explore the optimum operating condition of the CI engine run in dual-fuel mode. The experiments are performed on a four-strokes CI engine with rated output power of 4.41 kW. The engine is tested at constant speed 1500 rpm. The engine load varied from 600W to 1500W and biogas flow rate varied from 0 L/min to 6 L/min. The results show brake thermal efficiency of the engine run in dual-fuel mode is better than pure diesel mode if the biogas flow rates are 2 L/min and 4 L/min. It is recommended to operate the present engine in a dual-fuel mode with biogas flow rate of 4 L/min. The consumption of diesel fuel can be replaced up to 50%.

Load Balancing Scientific Applications

Energy Technology Data Exchange (ETDEWEB)

Pearce, Olga Tkachyshyn [Texas A & M Univ., College Station, TX (United States)

2014-12-01

The largest supercomputers have millions of independent processors, and concurrency levels are rapidly increasing. For ideal efficiency, developers of the simulations that run on these machines must ensure that computational work is evenly balanced among processors. Assigning work evenly is challenging because many large modern parallel codes simulate behavior of physical systems that evolve over time, and their workloads change over time. Furthermore, the cost of imbalanced load increases with scale because most large-scale scientific simulations today use a Single Program Multiple Data (SPMD) parallel programming model, and an increasing number of processors will wait for the slowest one at the synchronization points. To address load imbalance, many large-scale parallel applications use dynamic load balance algorithms to redistribute work evenly. The research objective of this dissertation is to develop methods to decide when and how to load balance the application, and to balance it effectively and affordably. We measure and evaluate the computational load of the application, and develop strategies to decide when and how to correct the imbalance. Depending on the simulation, a fast, local load balance algorithm may be suitable, or a more sophisticated and expensive algorithm may be required. We developed a model for comparison of load balance algorithms for a specific state of the simulation that enables the selection of a balancing algorithm that will minimize overall runtime.

Effects of a plyometric training program with and without added load on jumping ability in basketball players.

Science.gov (United States)

Khlifa, Riadh; Aouadi, Ridha; Hermassi, Souhail; Chelly, Mohamed Souhaiel; Jlid, Mohamed Chedly; Hbacha, Hamdi; Castagna, Carlo

2010-11-01

The purpose of this investigation was to examine the effect of a standard plyometric training protocol with or without added load in improving vertical jumping ability in male basketball players. Twenty-seven players were randomly assigned to 3 groups: a control group (no plyometric training), plyometric training group (PG), and loaded plyometric group (LPG, weighted vests 10-11% body mass). Before and after the 10-week training program, all the players were tested for the 5-jump test (5JT), the squat jump (SJ), and the countermovement jump (CMJ). The PG and LPG groups performed 2 and 3 training sessions per week, during the first 3 and the last 7 weeks, respectively. The results showed that SJ, CMJ, and 5JT were significantly improved only in the PG and LPG groups. The best effects for jumps were observed in LPG (p training program may result in greater vertical and horizontal-jump performances in basketball players.

Exploring the role of flood transience in coarse bed load sediment transport

Science.gov (United States)

Phillips, C. B.; Singer, M. B.; Hill, K. M.; Paola, C.

2015-12-01

The rate of bed load transport under steady flow is known to vary both spatially and temporally due to various hydrologic and granular phenomena. Grain size distributions and riverbed properties (packing, imbrication, etc.) are known to affect flux for a particular value of applied flow stress, while hydrology is mainly assumed to control the magnitude of the applied bed stress above the threshold for bed material entrainment. The prediction of bed load sediment transport in field settings is further complicated by the inherent transience in flood hydrology, but little is known about how such flood transience influences bed load flux over a range of applied bed stress. Here we investigate the role of flood transience for gravel bed load transport through controlled laboratory experiments in a 28 m long 0.5 meter wide flume. We explore transient flow as the combination of unsteady and intermittent flow, where unsteady flow varies in magnitude over a given duration, and intermittent flow is characterized by turning the flow on and off. We systematically vary these details of flood hydrographs from one experiment to the next, and monitor the bed load as it varies with water discharge in real time by measuring sediment flux and tracking particles. We find that even with a narrow unimodal grain size distribution and constant sediment supply we observe hysteresis in bed load flux, different thresholds for entrainment and distrainment for the rising and falling limbs of a flood, and a threshold of entrainment that can vary one flood hydrograph to the next. Despite these complex phenomena we find that the total bed load transported for each flood plots along a linear trend with the integrated excess stress, consistent with prior field results. These results suggest that while the effects of transient flow and the shape of the hydrograph are measurable, they are second-order compared to the integrated excess stress.

Annual trace-metal load estimates and flow-weighted concentrations of cadmium, lead, and zinc in the Spokane River basin, Idaho and Washington, 1999-2004

Science.gov (United States)

Donato, Mary M.

2006-01-01

Streamflow and trace-metal concentration data collected at 10 locations in the Spokane River basin of northern Idaho and eastern Washington during 1999-2004 were used as input for the U.S. Geological Survey software, LOADEST, to estimate annual loads and mean flow-weighted concentrations of total and dissolved cadmium, lead, and zinc. Cadmium composed less than 1 percent of the total metal load at all stations; lead constituted from 6 to 42 percent of the total load at stations upstream from Coeur d'Alene Lake and from 2 to 4 percent at stations downstream of the lake. Zinc composed more than 90 percent of the total metal load at 6 of the 10 stations examined in this study. Trace-metal loads were lowest at the station on Pine Creek below Amy Gulch, where the mean annual total cadmium load for 1999-2004 was 39 kilograms per year (kg/yr), the mean estimated total lead load was about 1,700 kg/yr, and the mean annual total zinc load was 14,000 kg/yr. The trace-metal loads at stations on North Fork Coeur d'Alene River at Enaville, Ninemile Creek, and Canyon Creek also were relatively low. Trace-metal loads were highest at the station at Coeur d'Alene River near Harrison. The mean annual total cadmium load was 3,400 kg/yr, the mean total lead load was 240,000 kg/yr, and the mean total zinc load was 510,000 kg/yr for 1999-2004. Trace-metal loads at the station at South Fork Coeur d'Alene River near Pinehurst and the three stations on the Spokane River downstream of Coeur d'Alene Lake also were relatively high. Differences in metal loads, particularly lead, between stations upstream and downstream of Coeur d'Alene Lake likely are due to trapping and retention of metals in lakebed sediments. LOADEST software was used to estimate loads for water years 1999-2001 for many of the same sites discussed in this report. Overall, results from this study and those from a previous study are in good agreement. Observed differences between the two studies are attributable to streamflow

MP Salsa: a finite element computer program for reacting flow problems. Part 1--theoretical development

Energy Technology Data Exchange (ETDEWEB)

Shadid, J.N.; Moffat, H.K.; Hutchinson, S.A.; Hennigan, G.L.; Devine, K.D.; Salinger, A.G.

1996-05-01

The theoretical background for the finite element computer program, MPSalsa, is presented in detail. MPSalsa is designed to solve laminar, low Mach number, two- or three-dimensional incompressible and variable density reacting fluid flows on massively parallel computers, using a Petrov-Galerkin finite element formulation. The code has the capability to solve coupled fluid flow, heat transport, multicomponent species transport, and finite-rate chemical reactions, and to solver coupled multiple Poisson or advection-diffusion- reaction equations. The program employs the CHEMKIN library to provide a rigorous treatment of multicomponent ideal gas kinetics and transport. Chemical reactions occurring in the gas phase and on surfaces are treated by calls to CHEMKIN and SURFACE CHEMKIN, respectively. The code employs unstructured meshes, using the EXODUS II finite element data base suite of programs for its input and output files. MPSalsa solves both transient and steady flows by using fully implicit time integration, an inexact Newton method and iterative solvers based on preconditioned Krylov methods as implemented in the Aztec solver library.

Reactor pressure elevation preventing device upon interruption of load

International Nuclear Information System (INIS)

Ota, Yasuo; Okukawa, Ryutaro.

1996-01-01

In a power load imbalance circuit of a steam turbine control device, a power load imbalance occurrence signal is outputted for a predetermined period of time upon occurrence of load interruption. A function for suppressing increase of number of rotation of a turbine due to load interruption is not disturbed, and the power load imbalance circuit is not operated at least after a primary peak where the number of rotation of the turbine is increased. Since a steam control valve flow rate demand signal and a turbine bypass valve flow rate demand signals are corporated subsequently to control the opening degree of the steam control valve and the turbine bypass valve, elevation of reactor pressure is always suppressed and maintained constant, as well as abrupt opening of the steam control valve due to cancel of the power load imbalance circuit when steam control valve opening demand is outputted can be prevented. (N.H.)

Probabilistic Load-Flow Analysis of Biomass-Fuelled Gas Engines with Electrical Vehicles in Distribution Systems

Directory of Open Access Journals (Sweden)

Francisco J. Ruiz-Rodríguez

2017-10-01

Full Text Available Feeding biomass-fueled gas engines (BFGEs with olive tree pruning residues offers new opportunities to decrease fossil fuel use in road vehicles and electricity generation. BFGEs, coupled to radial distribution systems (RDSs, provide renewable energy and power that can feed electric vehicle (EV charging stations. However, the combined impact of BFGEs and EVs on RDSs must be assessed to assure the technical constraint fulfilment. Because of the stochastic nature of source/load, it was decided that a probabilistic approach was the most viable option for this assessment. Consequently, this research developed an analytical technique to evaluate the technical constraint fulfilment in RDSs with this combined interaction. The proposed analytical technique (PAT involved the calculation of cumulants and the linearization of load-flow equations, along with the application of the cumulant method, and Cornish-Fisher expansion. The uncertainties related to biomass stock and its heating value (HV were important factors that were assessed for the first time. Application of the PAT in a Spanish RDS with BFGEs and EVs confirmed the feasibility of the proposal and its additional benefits. Specifically, BFGEs were found to clearly contribute to the voltage constraint fulfilment. The computational cost of the PAT was lower than that associated with Monte-Carlo simulations (MCSs.

PHAST--a program for simulating ground-water flow, solute transport, and multicomponent geochemical reactions

Science.gov (United States)

Parkhurst, David L.; Kipp, Kenneth L.; Engesgaard, Peter; Charlton, Scott R.

2004-01-01

The computer program PHAST simulates multi-component, reactive solute transport in three-dimensional saturated ground-water flow systems. PHAST is a versatile ground-water flow and solute-transport simulator with capabilities to model a wide range of equilibrium and kinetic geochemical reactions. The flow and transport calculations are based on a modified version of HST3D that is restricted to constant fluid density and constant temperature. The geochemical reactions are simulated with the geochemical model PHREEQC, which is embedded in PHAST. PHAST is applicable to the study of natural and contaminated ground-water systems at a variety of scales ranging from laboratory experiments to local and regional field scales. PHAST can be used in studies of migration of nutrients, inorganic and organic contaminants, and radionuclides; in projects such as aquifer storage and recovery or engineered remediation; and in investigations of the natural rock-water interactions in aquifers. PHAST is not appropriate for unsaturated-zone flow, multiphase flow, density-dependent flow, or waters with high ionic strengths. A variety of boundary conditions are available in PHAST to simulate flow and transport, including specified-head, flux, and leaky conditions, as well as the special cases of rivers and wells. Chemical reactions in PHAST include (1) homogeneous equilibria using an ion-association thermodynamic model; (2) heterogeneous equilibria between the aqueous solution and minerals, gases, surface complexation sites, ion exchange sites, and solid solutions; and (3) kinetic reactions with rates that are a function of solution composition. The aqueous model (elements, chemical reactions, and equilibrium constants), minerals, gases, exchangers, surfaces, and rate expressions may be defined or modified by the user. A number of options are available to save results of simulations to output files. The data may be saved in three formats: a format suitable for viewing with a text editor; a

Development of free-flowing peppermint essential oil-loaded hollow solid lipid micro- and nanoparticles via atomization with carbon dioxide.

Science.gov (United States)

Yang, Junsi; Ciftci, Ozan Nazim

2016-09-01

The main objective of this study was to overcome the issues related to the volatility and strong smell that limit the efficient utilization of essential oils as "natural" antimicrobials in the food industry. Peppermint essential oil-loaded hollow solid lipid micro- and nanoparticles were successfully formed using a novel "green" method based on atomization of CO 2 -expanded lipid mixture. The highest essential oil loading efficiency (47.5%) was achieved at 50% initial essential oil concentration at 200bar expansion pressure and 50μm nozzle diameter, whereas there was no significant difference between the loading efficiencies (35%-39%) at 5%, 7%, 10%, and 20% initial essential oil concentrations (p>0.05). Particles generated at all initial essential oil concentrations were spherical but increasing the initial essential oil concentration to 20% and 50% generated a less smooth particle surface. After 4weeks of storage, 61.2%, 42.5%, 0.2%, and 2.0% of the loaded essential oil was released from the particles formed at 5%, 10%, 20%, and 50% initial essential oil concentrations, respectively. This innovative simple and clean process is able to form spherical hollow micro- and nanoparticles loaded with essential oil that can be used as food grade antimicrobials. These novel hollow solid lipid micro- and nanoparticles are alternatives to the solid lipid nanoparticles, and overcome the issues associated with the solid lipid nanoparticles. The dry free-flowing products make the handling and storage more convenient, and the simple and clean process makes the scaling up more feasible. Copyright © 2016 Elsevier Ltd. All rights reserved.

Large LOCA-earthquake combination probability assessment - Load combination program. Project 1 summary report

Energy Technology Data Exchange (ETDEWEB)

Lu, S; Streit, R D; Chou, C K

1980-01-01

This report summarizes work performed for the U.S. Nuclear Regulatory Commission (NRC) by the Load Combination Program at the Lawrence Livermore National Laboratory to establish a technical basis for the NRC to use in reassessing its requirement that earthquake and large loss-of-coolant accident (LOCA) loads be combined in the design of nuclear power plants. A systematic probabilistic approach is used to treat the random nature of earthquake and transient loading to estimate the probability of large LOCAs that are directly and indirectly induced by earthquakes. A large LOCA is defined in this report as a double-ended guillotine break of the primary reactor coolant loop piping (the hot leg, cold leg, and crossover) of a pressurized water reactor (PWR). Unit 1 of the Zion Nuclear Power Plant, a four-loop PWR-1, is used for this study. To estimate the probability of a large LOCA directly induced by earthquakes, only fatigue crack growth resulting from the combined effects of thermal, pressure, seismic, and other cyclic loads is considered. Fatigue crack growth is simulated with a deterministic fracture mechanics model that incorporates stochastic inputs of initial crack size distribution, material properties, stress histories, and leak detection probability. Results of the simulation indicate that the probability of a double-ended guillotine break, either with or without an earthquake, is very small (on the order of 10{sup -12}). The probability of a leak was found to be several orders of magnitude greater than that of a complete pipe rupture. A limited investigation involving engineering judgment of a double-ended guillotine break indirectly induced by an earthquake is also reported. (author)

Large LOCA-earthquake combination probability assessment - Load combination program. Project 1 summary report

International Nuclear Information System (INIS)

Lu, S.; Streit, R.D.; Chou, C.K.

1980-01-01

This report summarizes work performed for the U.S. Nuclear Regulatory Commission (NRC) by the Load Combination Program at the Lawrence Livermore National Laboratory to establish a technical basis for the NRC to use in reassessing its requirement that earthquake and large loss-of-coolant accident (LOCA) loads be combined in the design of nuclear power plants. A systematic probabilistic approach is used to treat the random nature of earthquake and transient loading to estimate the probability of large LOCAs that are directly and indirectly induced by earthquakes. A large LOCA is defined in this report as a double-ended guillotine break of the primary reactor coolant loop piping (the hot leg, cold leg, and crossover) of a pressurized water reactor (PWR). Unit 1 of the Zion Nuclear Power Plant, a four-loop PWR-1, is used for this study. To estimate the probability of a large LOCA directly induced by earthquakes, only fatigue crack growth resulting from the combined effects of thermal, pressure, seismic, and other cyclic loads is considered. Fatigue crack growth is simulated with a deterministic fracture mechanics model that incorporates stochastic inputs of initial crack size distribution, material properties, stress histories, and leak detection probability. Results of the simulation indicate that the probability of a double-ended guillotine break, either with or without an earthquake, is very small (on the order of 10 -12 ). The probability of a leak was found to be several orders of magnitude greater than that of a complete pipe rupture. A limited investigation involving engineering judgment of a double-ended guillotine break indirectly induced by an earthquake is also reported. (author)

Simulation of load traffic and steeped speed control of conveyor

Science.gov (United States)

Reutov, A. A.

2017-10-01

The article examines the possibilities of the step control simulation of conveyor speed within Mathcad, Simulink, Stateflow software. To check the efficiency of the control algorithms and to more accurately determine the characteristics of the control system, it is necessary to simulate the process of speed control with real values of traffic for a work shift or for a day. For evaluating the belt workload and absence of spillage it is necessary to use empirical values of load flow in a shorter period of time. The analytical formulas for optimal speed step values were received using empirical values of load. The simulation checks acceptability of an algorithm, determines optimal parameters of regulation corresponding to load flow characteristics. The average speed and the number of speed switching during simulation are admitted as criteria of regulation efficiency. The simulation example within Mathcad software is implemented. The average conveyor speed decreases essentially by two-step and three-step control. A further increase in the number of regulatory steps decreases average speed insignificantly but considerably increases the intensity of the speed switching. Incremental algorithm of speed regulation uses different number of stages for growing and reducing load traffic. This algorithm allows smooth control of the conveyor speed changes with monotonic variation of the load flow. The load flow oscillation leads to an unjustified increase or decrease of speed. Work results can be applied at the design of belt conveyors with adjustable drives.

Structural load combinations

International Nuclear Information System (INIS)

Hwang, H.; Reich, M.; Ellingwood, B.; Shinozuka, M.

1985-01-01

This paper presents the latest results of the program entitled, ''Probability Based Load Combinations For Design of Category I Structures''. In FY 85, a probability-based reliability analysis method has been developed to evaluate safety of shear wall structures. The shear walls are analyzed using stick models with beam elements and may be subjected to dead load, live load and in-plane eqrthquake. Both shear and flexure limit states are defined analytically. The limit state probabilities can be evaluated on the basis of these limit states. Utilizing the reliability analysis method mentioned above, load combinations for the design of shear wall structures have been established. The proposed design criteria are in the load and resistance factor design (LRFD) format. In this study, the resistance factors for shear and flexure and load factors for dead and live loads are preassigned, while the load factor for SSE is determined for a specified target limit state probability of 1.0 x 10 -6 or 1.0 x 10 -5 during a lifetime of 40 years. 23 refs., 9 tabs

Structural load combinations

International Nuclear Information System (INIS)

Hwang, H.; Reich, M.; Ellingwood, B.; Shinozuka, M.

1986-01-01

This paper presents the latest results of the program entitled, ''Probability Based Load Combinations For Design of Category I Structures''. In FY 85, a probability-based reliability analysis method has been developed to evaluate safety of shear wall structures. The shear walls are analyzed using stick models with beam elements and may be subjected to dead load, live load and in-plane earthquake. Both shear and flexure limit states are defined analytically. The limit state probabilities can be evaluated on the basis of these limit states. Utilizing the reliability analysis method mentioned above, load combinations for the design of shear wall structures have been established. The proposed design criteria are in the load and resistance factor design (LRFD) format. In this study, the resistance factors for shear and flexure and load factors for dead and live loads are preassigned, while the load factor for SSE is determined for a specified target limit state probability of 1.0 x 10 -6 or 1.0 x 10 -5 during a lifetime of 40 years

STAFAN, Fluid Flow, Mechanical Stress in Fractured Rock of Nuclear Waste Repository

International Nuclear Information System (INIS)

Huyakorn, P.; Golis, M.J.

1989-01-01

1 - Description of program or function: STAFAN (Stress And Flow Analysis) is a two-dimensional, finite-element code designed to model fluid flow and the interaction of fluid pressure and mechanical stresses in a fractured rock surrounding a nuclear waste repository. STAFAN considers flow behavior of a deformable fractured system with fracture-porous matrix interactions, the coupling effects of fluid pressure and mechanical stresses in a medium containing discrete joints, and the inelastic response of the individual joints of the rock mass subject to the combined fluid pressure and mechanical loading. 2 - Restrictions on the complexity of the problem: STAFAN does not presently contain thermal coupling, and it is unable to simulate inelastic deformation of the rock mass and variably saturated or two-phase flow in the fractured porous medium system

Algorithms for parallel flow solvers on message passing architectures

Science.gov (United States)

Vanderwijngaart, Rob F.

1995-01-01

The purpose of this project has been to identify and test suitable technologies for implementation of fluid flow solvers -- possibly coupled with structures and heat equation solvers -- on MIMD parallel computers. In the course of this investigation much attention has been paid to efficient domain decomposition strategies for ADI-type algorithms. Multi-partitioning derives its efficiency from the assignment of several blocks of grid points to each processor in the parallel computer. A coarse-grain parallelism is obtained, and a near-perfect load balance results. In uni-partitioning every processor receives responsibility for exactly one block of grid points instead of several. This necessitates fine-grain pipelined program execution in order to obtain a reasonable load balance. Although fine-grain parallelism is less desirable on many systems, especially high-latency networks of workstations, uni-partition methods are still in wide use in production codes for flow problems. Consequently, it remains important to achieve good efficiency with this technique that has essentially been superseded by multi-partitioning for parallel ADI-type algorithms. Another reason for the concentration on improving the performance of pipeline methods is their applicability in other types of flow solver kernels with stronger implied data dependence. Analytical expressions can be derived for the size of the dynamic load imbalance incurred in traditional pipelines. From these it can be determined what is the optimal first-processor retardation that leads to the shortest total completion time for the pipeline process. Theoretical predictions of pipeline performance with and without optimization match experimental observations on the iPSC/860 very well. Analysis of pipeline performance also highlights the effect of uncareful grid partitioning in flow solvers that employ pipeline algorithms. If grid blocks at boundaries are not at least as large in the wall-normal direction as those

Thermal models of buildings. Determination of temperatures, heating and cooling loads. Theories, models and computer programs

Energy Technology Data Exchange (ETDEWEB)

Kaellblad, K

1998-05-01

The need to estimate indoor temperatures, heating or cooling load and energy requirements for buildings arises in many stages of a buildings life cycle, e.g. at the early layout stage, during the design of a building and for energy retrofitting planning. Other purposes are to meet the authorities requirements given in building codes. All these situations require good calculation methods. The main purpose of this report is to present the authors work with problems related to thermal models and calculation methods for determination of temperatures and heating or cooling loads in buildings. Thus the major part of the report deals with treatment of solar radiation in glazing systems, shading of solar and sky radiation and the computer program JULOTTA used to simulate the thermal behavior of rooms and buildings. Other parts of thermal models of buildings are more briefly discussed and included in order to give an overview of existing problems and available solutions. A brief presentation of how thermal models can be built up is also given and it is a hope that the report can be useful as an introduction to this part of building physics as well as during development of calculation methods and computer programs. The report may also serve as a help for the users of energy related programs. Independent of which method or program a user choose to work with it is his or her own responsibility to understand the limits of the tool, else wrong conclusions may be drawn from the results 52 refs, 22 figs, 4 tabs

Blade bowing effects on radial equilibrium of inlet flow in axial compressor cascades

Directory of Open Access Journals (Sweden)

Han XU

2017-10-01

Full Text Available The circumferentially averaged equation of the inlet flow radial equilibrium in axial compressor was deduced. It indicates that the blade inlet radial pressure gradient is closely related to the radial component of the circumferential fluctuation (CF source item. Several simplified cascades with/without aerodynamic loading were numerically studied to investigate the effects of blade bowing on the inlet flow radial equilibrium. A data reduction program was conducted to obtain the CF source from three-dimensional (3D simulation results. Flow parameters at the passage inlet were focused on and each term in the radial equilibrium equation was discussed quantitatively. Results indicate that the inviscid blade force is the inducement of the inlet CF due to geometrical asymmetry. Blade bowing induces variation of the inlet CF, thus changes the radial pressure gradient and leads to flow migration before leading edge (LE in the cascades. Positive bowing drives the inlet flow to migrate from end walls to mid-span and negative bowing turns it to the reverse direction to build a new equilibrium. In addition, comparative studies indicate that the inlet Mach number and blade loading can efficiently impact the effectiveness of blade bowing on radial equilibrium in compressor design.

Diffuse Ceiling Ventilation and the Influence of Room Height and Heat Load Distribution

DEFF Research Database (Denmark)

Nielsen, Peter Vilhelm; Vilsbøll, Rasmus W; Liu, Li

2015-01-01

Diffuse ceiling (inlet) ventilation is an air distribution system that supplies air from the entire ceiling surface, giving a low supply velocity. The flow pattern in the room is controlled by the heat sources. The system generates high mixing flow and the air velocities in the room are expected...... to be not much influenced by the flow rate to the room but dependent on the heat load. Previous studies have shown that diffuse ceiling ventilation has an ability to remove large heat loads without compromising the indoor climate. However, recent experiments indicate that the maximum accepted heat load decreases...... with a large room height and it decreases in connection with certain heat load distributions. Room geometries and heat load distributions that are optimal for diffuse ceiling ventilation are discussed. A simplified design procedure is introduced....

PHAST Version 2-A Program for Simulating Groundwater Flow, Solute Transport, and Multicomponent Geochemical Reactions

Science.gov (United States)

Parkhurst, David L.; Kipp, Kenneth L.; Charlton, Scott R.

2010-01-01

The computer program PHAST (PHREEQC And HST3D) simulates multicomponent, reactive solute transport in three-dimensional saturated groundwater flow systems. PHAST is a versatile groundwater flow and solute-transport simulator with capabilities to model a wide range of equilibrium and kinetic geochemical reactions. The flow and transport calculations are based on a modified version of HST3D that is restricted to constant fluid density and constant temperature. The geochemical reactions are simulated with the geochemical model PHREEQC, which is embedded in PHAST. Major enhancements in PHAST Version 2 allow spatial data to be defined in a combination of map and grid coordinate systems, independent of a specific model grid (without node-by-node input). At run time, aquifer properties are interpolated from the spatial data to the model grid; regridding requires only redefinition of the grid without modification of the spatial data. PHAST is applicable to the study of natural and contaminated groundwater systems at a variety of scales ranging from laboratory experiments to local and regional field scales. PHAST can be used in studies of migration of nutrients, inorganic and organic contaminants, and radionuclides; in projects such as aquifer storage and recovery or engineered remediation; and in investigations of the natural rock/water interactions in aquifers. PHAST is not appropriate for unsaturated-zone flow, multiphase flow, or density-dependent flow. A variety of boundary conditions are available in PHAST to simulate flow and transport, including specified-head, flux (specified-flux), and leaky (head-dependent) conditions, as well as the special cases of rivers, drains, and wells. Chemical reactions in PHAST include (1) homogeneous equilibria using an ion-association or Pitzer specific interaction thermodynamic model; (2) heterogeneous equilibria between the aqueous solution and minerals, ion exchange sites, surface complexation sites, solid solutions, and gases; and

Flow discharge prediction in compound channels using linear genetic programming

Science.gov (United States)

Azamathulla, H. Md.; Zahiri, A.

2012-08-01

SummaryFlow discharge determination in rivers is one of the key elements in mathematical modelling in the design of river engineering projects. Because of the inundation of floodplains and sudden changes in river geometry, flow resistance equations are not applicable for compound channels. Therefore, many approaches have been developed for modification of flow discharge computations. Most of these methods have satisfactory results only in laboratory flumes. Due to the ability to model complex phenomena, the artificial intelligence methods have recently been employed for wide applications in various fields of water engineering. Linear genetic programming (LGP), a branch of artificial intelligence methods, is able to optimise the model structure and its components and to derive an explicit equation based on the variables of the phenomena. In this paper, a precise dimensionless equation has been derived for prediction of flood discharge using LGP. The proposed model was developed using published data compiled for stage-discharge data sets for 394 laboratories, and field of 30 compound channels. The results indicate that the LGP model has a better performance than the existing models.

Concentrations and Loads of Organic Compounds and Trace Elements in Tributaries to Newark and Raritan Bays, New Jersey

Science.gov (United States)

Wilson, Timothy P.; Bonin, Jennifer L.

2007-01-01

A study was undertaken to determine the concentrations and loads of sediment and chemicals delivered to Newark and Raritan Bays by five major tributaries: the Raritan, Passaic, Rahway, Elizabeth, and Hackensack Rivers. This study was initiated by the State of New Jersey as Study I-C of the New Jersey Toxics Reduction Workplan for the New York-New Jersey Harbor, working under the NY-NJ Harbor Estuary Program (HEP) Contaminant Assessment and Reduction Program (CARP). The CARP is a comprehensive effort to evaluate the levels and sources of toxic contaminants to the tributaries and estuarine areas of the NY-NJ Harbor, including Newark and Raritan Bays. The Raritan and Passaic Rivers are large rivers (mean daily discharges of 1,189 and 1,132 cubic feet per second (ft3/s), respectively), that drain large, mixed rural/urban basins. The Elizabeth and Rahway Rivers are small rivers (mean daily discharges of 25.9 and 49.1 ft3/s, respectively) that drain small, highly urbanized and industrialized basins. The Hackensack River drains a small, mixed rural/urban basin, and its flow is highly controlled by an upstream reservoir (mean daily discharge of 90.4 ft3/s). These rivers flow into urbanized estuaries and ultimately, to the Atlantic Ocean. Each of these tributaries were sampled during two to four storm events, and twice each during low-flow discharge conditions. Samples were collected using automated equipment installed at stations adjacent to U.S. Geological Survey streamflow-gaging stations near the heads-of-tide of these rivers. Large-volume (greater than 50 liters of water and a target of 1 gram of sediment), flow-weighted composite samples were collected for chemical analysis using filtration to collect suspended particulates and exchange resin (XAD-2) to sequester dissolved contaminants. Composite whole-water samples were collected for dissolved polycyclic aromatic hydrocarbons (PAH) and for trace element analysis. Additional discrete grab samples were collected

Aging and low-flow degradation of auxilary feedwater pumps

International Nuclear Information System (INIS)

Adams, M.L.

1992-01-01

This paper documents the results of research done under the auspices of the Nuclear Regulatory Commission Nuclear Plant Aging Research Program. It examines the degradation imparted to safety related Auxiliary Feedwater System pumps at nuclear plants due to the low flow operation. The Auxiliary Feedwater (AFW) System is normally a stand-by system. As such it is operated most often in the test mode. Since few plants are equipped with full flow test loops, most testing is accomplished at minimum flow conditions in pump by-pass lines. It is the vibration and hydraulic forces generated at low flow conditions that have been shown to be the major causes of AFW pump aging and degradation. The wear can be manifested in a number of ways, such as impeller or diffuser breakage, thrust bearing and/or balance device failure due to excessive loading, cavitation damage on such stage impellers, increase seal leakage or failure, sear injection piping failure, shaft or coupling breakage, and rotating element seizure

Aging and low-flow degradation of auxiliary feedwater pumps

International Nuclear Information System (INIS)

Adams, M.L.

1991-01-01

This paper documents the results of research done under the auspices of the Nuclear Regulatory Commission Nuclear Plant Aging Research Program. It examines the degradation imparted to safety Auxiliary Feedwater System pumps at nuclear plants due to the low flow operation. The Auxiliary Feedwater (AFW) System is normally a stand-by system. As such it is operated most often in the test mode. Since few plants are equipped with full flow test loops, most testing is accomplished at minimum flow conditions in pump by-pass lines. It is the vibration and hydraulic forces generated at low flow conditions that have been shown to be the major causes of AFW pump aging and degradation. The wear can be manifested in a number of ways, such as impeller or diffuser breakage, thrust bearing and/or balance device failure due to excessive loading, cavitation damage on such stage impellers, increase seal leakage or failure, sear injection piping failure, shaft or coupling breakage, and rotating element seizure

Generalized Analytical Program of Thyristor Phase Control Circuit with Series and Parallel Resonance Load

OpenAIRE

Nakanishi, Sen-ichiro; Ishida, Hideaki; Himei, Toyoji

1981-01-01

The systematic analytical method is reqUired for the ac phase control circuit by means of an inverse parallel thyristor pair which has a series and parallel L-C resonant load, because the phase control action causes abnormal and interesting phenomena, such as an extreme increase of voltage and current, an unique increase and decrease of contained higher harmonics, and a wide variation of power factor, etc. In this paper, the program for the analysis of the thyristor phase control circuit with...

Convolute laminations and load structures in turbidites as indicators of flow reflections and decelerations against bounding slopes. Examples from the Marnoso-arenacea Formation (northern Italy) and Annot Sandstones (south eastern France)

Science.gov (United States)

Tinterri, R.; Muzzi Magalhaes, P.; Tagliaferri, A.; Cunha, R. S.

2016-10-01

This work discusses the significance of particular types of soft-sediment deformations very common within turbidite deposits, namely convolute laminations and load structures. Detailed facies analyses of the foredeep turbidites in the Marnoso-arenacea Formation (northern Italy) and Annot Sandstones (south eastern France) show that these deformational structures tend to increase near morphological obstacles, concomitantly with contained-reflected beds. The lateral and vertical distribution of convolute laminae and load structures, as well as their geometry, has a well-defined depositional logic related to flow decelerations and reflections against bounding slopes. This evidence suggests an interaction between fine-grained sediment and the presence of morphologic relief, and impulsive and cyclic-wave loadings, which are produced by flow impacts or reflected bores and internal waves related to impinging bipartite turbidity currents.

New perspective on gas-well liquid loading and unloading

NARCIS (Netherlands)

Veeken, C.A.M.; Belfroid, S.P.C.

2010-01-01

This paper discusses the multiphase flow mechanism responsible for gas-well liquid loading. It shows that the conventional idea of droplet flow reversal (Turner et al. (1969)) does not capture reality and that actual observations are better described by film flow reversal. This paper subsequently

Diffusion or bulk flow

DEFF Research Database (Denmark)

Schulz, Alexander

2015-01-01

is currently matter of discussion, called passive symplasmic loading. Based on the limited material available, this review compares the different loading modes and suggests that diffusion is the driving force in apoplasmic loaders, while bulk flow plays an increasing role in plants having a continuous...

NACHOS: a finite element computer program for incompressible flow problems. Part I. Theoretical background

International Nuclear Information System (INIS)

Gartling, D.K.

1978-04-01

The theoretical background for the finite element computer program, NACHOS, is presented in detail. The NACHOS code is designed for the two-dimensional analysis of viscous incompressible fluid flows, including the effects of heat transfer. A general description of the fluid/thermal boundary value problems treated by the program is described. The finite element method and the associated numerical methods used in the NACHOS code are also presented. Instructions for use of the program are documented in SAND77-1334

Technical Evaluation Report, Part A - Vortex Flow and High Angle of Attack

Science.gov (United States)

Luckring, James M.

2003-01-01

A symposium entitled Vortex Flow and High Angle of Attack was held in Loen, Norway, from May 7 through May 11, 2001. The Applied Vehicle Technology (AVT) panel, under the auspices of the Research and Technology Organization (RTO), sponsored this symposium. Forty-eight papers, organized into nine sessions, addressed computational and experimental studies of vortex flows pertinent to both aircraft and maritime applications. The studies also ranged from fundamental fluids investigations to flight test results, and significant results were contributed from a broad range of countries. The principal emphasis of this symposium was on "the understanding and prediction of separation-induced vortex flows and their effects on military vehicle performance, stability, control, and structural design loads." It was further observed by the program committee that "separation- induced vortex flows are an important part of the design and off-design performance of conventional fighter aircraft and new conventional or unconventional manned or unmanned advanced vehicle designs (UAVs, manned aircraft, missiles, space planes, ground-based vehicles, and ships)." The nine sessions addressed the following topics: vortical flows on wings and bodies, experimental techniques for vortical flows, numerical simulations of vortical flows, vortex stability and breakdown, vortex flows in maritime applications, vortex interactions and control, vortex dynamics, flight testing, and vehicle design. The purpose of this paper is to provide brief reviews of these papers along with some synthesizing perspectives toward future vortex flow research opportunities. The paper includes the symposium program. (15 refs.)

The Atlas load protection switch

CERN Document Server

Davis, H A; Dorr, G; Martínez, M; Gribble, R F; Nielsen, K E; Pierce, D; Parsons, W M

1999-01-01

Atlas is a high-energy pulsed-power facility under development to study materials properties and hydrodynamics experiments under extreme conditions. Atlas will implode heavy liner loads (m~45 gm) with a peak current of 27-32 MA delivered in 4 mu s, and is energized by 96, 240 kV Marx generators storing a total of 23 MJ. A key design requirement for Atlas is obtaining useful data for 95601130f all loads installed on the machine. Materials response calculations show current from a prefire can damage the load requiring expensive and time consuming replacement. Therefore, we have incorporated a set of fast-acting mechanical switches in the Atlas design to reduce the probability of a prefire damaging the load. These switches, referred to as the load protection switches, short the load through a very low inductance path during system charge. Once the capacitors have reached full charge, the switches open on a time scale short compared to the bank charge time, allowing current to flow to the load when the trigger pu...

KUEBEL. A Fortran program for computation of cooling-agent-distribution within reactor fuel-elements

International Nuclear Information System (INIS)

Inhoven, H.

1984-12-01

KUEBEL is a Fortran-program for computation of cooling-agent-distribution within reactor fuel-elements or -zones of theirs. They may be assembled of max. 40 cooling-channels with laminar up to turbulent type of flow (respecting Reynolds' coefficients up to 2.0E+06) at equal pressure loss. Flow-velocity, dynamic flow-, contraction- and friction-losses will be calculated for each channel and for the total zone. Other computations will present mean heat-up of cooling-agent, mean outlet-temperature of the core, boiling-temperature and absolute pressure at flow-outlet. All characteristic coolant-values, including the factor of safety for flow-instability of the most-loaded cooling gap are computed by 'KUEBEL' too. Absolute pressure at flow-outlet or is-factor may be defined as dependent or independent variables of the program alternatively. In latter case 3 variations of solution will be available: Adapted flow of cooling-agent, inlet-temperature of the core and thermal power. All calculations can be done alternatively with variation of parameters: flow of cooling-agent, inlet-temperature of the core and thermal power, which are managed by the program itself. 'KUEBEL' is able to distinguish light- and heavy-water coolant, flow-direction of coolant and fuel elements with parallel, rectangular, respectively concentric, cylindrical shape of their gaps. Required material specifics are generated by the program. Segments of fuel elements or constructively unconnected gaps can also be computed by means of interposition of S.C. 'phantom channels'. (orig.) [de

Improving the steady-state loading margin to voltage collapse in the North-West Control Area of the Mexican Power System

Energy Technology Data Exchange (ETDEWEB)

Calderon-Guizar, J.G.; Inda-Ruiz, G.A.; Tovar, G.E. [Gerencia de Analisis de Redes, Temixco, Morelos (Mexico). Inst. de Investigaciones Eleectricas

2003-10-01

This paper reports the application of a static approach for assessing the steady-state loading margin to voltage collapse of the North-West Control Area (NWCA) of the Mexican Power System. The approach uses both optimal load flow (OLF) and conventional load flow (LF) solutions, and singular value decomposition of the load flow Jacobian matrix (J). Additionally, the approach allows to determine suitable locations for corrective actions such as, the addition of new equipment or load shedding. The results shows that the combination of OLF and LF resulted in a steady-state loading margin to voltage collapse of the NWCA 7.2% higher than the case when only conventional load flow solutions were considered. (author)

Diffusion and bulk flow in phloem loading: A theoretical analysis of the polymer trap mechanism for sugar transport in plants

Science.gov (United States)

Dölger, Julia; Rademaker, Hanna; Liesche, Johannes; Schulz, Alexander; Bohr, Tomas

2014-10-01

Plants create sugar in the mesophyll cells of their leaves by photosynthesis. This sugar, mostly sucrose, has to be loaded via the bundle sheath into the phloem vascular system (the sieve elements), where it is distributed to growing parts of the plant. We analyze the feasibility of a particular loading mechanism, active symplasmic loading, also called the polymer trap mechanism, where sucrose is transformed into heavier sugars, such as raffinose and stachyose, in the intermediary-type companion cells bordering the sieve elements in the minor veins of the phloem. Keeping the heavier sugars from diffusing back requires that the plasmodesmata connecting the bundle sheath with the intermediary cell act as extremely precise filters, which are able to distinguish between molecules that differ by less than 20% in size. In our modeling, we take into account the coupled water and sugar movement across the relevant interfaces, without explicitly considering the chemical reactions transforming the sucrose into the heavier sugars. Based on the available data for plasmodesmata geometry, sugar concentrations, and flux rates, we conclude that this mechanism can in principle function, but that it requires pores of molecular sizes. Comparing with the somewhat uncertain experimental values for sugar export rates, we expect the pores to be only 5%-10% larger than the hydraulic radius of the sucrose molecules. We find that the water flow through the plasmodesmata, which has not been quantified before, contributes only 10%-20% to the sucrose flux into the intermediary cells, while the main part is transported by diffusion. On the other hand, the subsequent sugar translocation into the sieve elements would very likely be carried predominantly by bulk water flow through the plasmodesmata. Thus, in contrast to apoplasmic loaders, all the necessary water for phloem translocation would be supplied in this way with no need for additional water uptake across the plasma membranes of the

State-of-the-art review of liquid loading in gas wells

Energy Technology Data Exchange (ETDEWEB)

Falcone, G. [Technische Univ. Clausthal, Clausthal-Zellerfeld (Germany). ITE; Barbosa, J.R. Jr. [Universidade Federal de Santa Catarina, Florianopolis, SC (Brazil). Dept. of Mechanical Engineering

2013-08-01

Gas wells suffering from liquid loading are incapable of removing the liquid associated with produced gas from the wellbore. This phenomenon is initiated when the upward gas velocity in the well falls below a critical value at which point the liquid that was initially flowing upwards, begins to fall back. This liquid accumulates downhole, where it increases the hydrostatic back-pressure on the reservoir, destabilises the multiphase flow in the well (following flow regime changes), decreases production rate and, in severe cases, kills the well. The typical liquid loading sequence begins with a gas flow rate that is high enough to transport all liquids to surface and there is no liquid fall-back in the well. However, as the gas velocity slows or the liquid content in the well rises, there is insufficient energy in the well to carry all liquids to surface and some begins to flow backwards. As the hydrostatic head downhole increases, the liquid column that has accumulated in the well can re-enter the near-wellbore region of the reservoir. This results in the well becoming 'unloaded' so that it can flow once more, with the gas carrying all liquids to surface. However, the reinjection of liquids into the reservoir may cause formation damage, which will impair the well productivity. This cycle continues, providing the typical intermittent response of liquid-loaded gas wells, until the reservoir potential starts to fall or the liquid yield rises. Diagnosing liquid loading is often difficult as the affected well(s) may continue production without any substantial performance impairment for a long period of time. Typical symptoms of liquid loading include sharp drops in the cumulative production decline curve, the onset of liquid slugs in the surface facilities, abrupt changes in the flowing pressure gradient, low temperature spikes at the wellhead and declining water production or condensate-gas-ratio. Many remedial lifting options have been developed for use in

Estudio del efecto del Compensador Estático de Reactivos en el problema de Flujo de Carga; Study of the effect of the Static Var Compensator on the Load Flow problem

Directory of Open Access Journals (Sweden)

Walter Ruiz Porras

2012-04-01

Full Text Available Este trabajo consiste en estudiar, modelar y simular un Compensador Estático de Reactivos (SVC, para analizar el efecto del mismo en el problema de Flujo de Carga de un Sistema Eléctrico de Potencia (SEP. Se emplea un programa, de la literatura revisada, escrito en Matlab. Se presenta el modelo matemático del SVC que se emplea en el programa y que utiliza el concepto de susceptancia en derivación variable e incorpora el modelo del ángulo de disparo de los tiristores como variable de estado en la fórmula de Newton Raphson. Se comparan los resultados obtenidos en el flujo de carga, sin SVC, en los ensayos que se realizan con el sistema de 9 barras de la IEEE con los resultados alcanzado utilizando la versión académica del Simulador Power World. El SVC se emplea para controlar el valor de la tensión en una de las barras del caso estudio.  This work consists on studying, to model and to simulate a Static Vars Compensator (SVC, to analyze the effect of the same one in the Load Flow problem of an Electric Power System (SEP. A program is used, of the revised literature, written in Matlab. The mathematical model of the SVC is presented that is used in the program and that it uses the concept of susceptance variable shunt and it incorporates the model of the fire angle of the tiristores like state variable in Newton Raphson methods. The results obtained are compared in the load flow, without SVC, in the rehearsals that are carried out with the system of 9 bars of the IEEE with the reached results using the academic version of the Power World Simulator. The SVC is used to control the value of the voltage in one of the bars of the case study.

Bed-load transportmeter for find sand "Sphinx"

NARCIS (Netherlands)

Vinckers, J.B.; Bijker, E.W.; Schijf, J.B.

1953-01-01

A new bed-load transportmeter has been designed particularly for very fine bed material (below 400 micron). The basic conception is the same as for the so-called Delft-bottle used for measuring transport by turbulent suspension. The instrument is of the flow-through type. The flow enters through a

THE INFLUENCE OF REPOSITORY THERMAL LOAD ON MULTIPHASE FLOW AND HEAT TRANSFER IN THE UNSATURATED ZONE OF YUCCA MOUNTAIN

International Nuclear Information System (INIS)

Yu-Shu Wu; Sumit Mukhopadhyay; Keni Zhang; G.S. Bodvarsson

2006-01-01

This paper investigates the impact of proposed repository thermal-loading on mountain-scale flow and heat transfer in the unsaturated fractured rock of Yucca Mountain, Nevada. In this context, a model has been developed to study the coupled thermal-hydrological (TH) processes at the scale of the entire Yucca Mountain. This mountain-scale TH model implements the current geological framework and hydrogeological conceptual models, and incorporates the latest rock thermal and hydrological properties. The TH model consists of a two-dimensional north-south vertical cross section across the entire unsaturated zone model domain and uses refined meshes near and around the proposed repository block, based on the current repository design, drift layout, thermal loading scenario, and estimated current and future climatic conditions. The model simulations provide insights into thermally affected liquid saturation, gas- and liquid-phase fluxes, and elevated water and rock temperature, which in turn allow modelers to predict the changes in water flux driven by evaporation/condensation processes, and drainage between drifts

Influence of Hydraulic Design on Stability and on Pressure Pulsations in Francis Turbines at Overload, Part Load and Deep Part Load based on Numerical Simulations and Experimental Model Test Results

International Nuclear Information System (INIS)

Magnoli, M V; Maiwald, M

2014-01-01

Francis turbines have been running more and more frequently in part load conditions, in order to satisfy the new market requirements for more dynamic and flexible energy generation, ancillary services and grid regulation. The turbines should be able to be operated for longer durations with flows below the optimum point, going from part load to deep part load and even speed-no-load. These operating conditions are characterised by important unsteady flow phenomena taking place at the draft tube cone and in the runner channels, in the respective cases of part load and deep part load. The current expectations are that new Francis turbines present appropriate hydraulic stability and moderate pressure pulsations at overload, part load, deep part load and speed-no-load with high efficiency levels at normal operating range. This study presents series of investigations performed by Voith Hydro with the objective to improve the hydraulic stability of Francis turbines at overload, part load and deep part load, reduce pressure pulsations and enlarge the know-how about the transient fluid flow through the turbine at these challenging conditions. Model test measurements showed that distinct runner designs were able to influence the pressure pulsation level in the machine. Extensive experimental investigations focused on the runner deflector geometry, on runner features and how they could reduce the pressure oscillation level. The impact of design variants and machine configurations on the vortex rope at the draft tube cone at overload and part load and on the runner channel vortex at deep part load were experimentally observed and evaluated based on the measured pressure pulsation amplitudes. Numerical investigations were employed for improving the understanding of such dynamic fluid flow effects. As example for the design and experimental investigations, model test observations and pressure pulsation curves for Francis machines in mid specific speed range, around n qopt = 50

Comparison of CFD-calculations of centrifugal compressor stages by NUMECA Fine Turbo and ANSYS CFX programs

Science.gov (United States)

Galerkin, Y. B.; Voinov, I. B.; Drozdov, A. A.

2017-08-01

Computational Fluid Dynamics (CFD) methods are widely used for centrifugal compressors design and flow analysis. The calculation results are dependent on the chosen software, turbulence models and solver settings. Two of the most widely applicable programs are NUMECA Fine Turbo and ANSYS CFX. The objects of the study were two different stages. CFD-calculations were made for a single blade channel and for full 360-degree flow paths. Stage 1 with 3D impeller and vaneless diffuser was tested experimentally. Its flow coefficient is 0.08 and loading factor is 0.74. For stage 1 calculations were performed with different grid quality, a different number of cells and different models of turbulence. The best results have demonstrated the Spalart-Allmaras model and mesh with 1.854 million cells. Stage 2 with return channel, vaneless diffuser and 3D impeller with flow coefficient 0.15 and loading factor 0.5 was designed by the known Universal Modeling Method. Its performances were calculated by the well identified Math model. Stage 2 performances by CFD calculations shift to higher flow rate in comparison with design performances. The same result was obtained for stage 1 in comparison with measured performances. Calculated loading factor is higher in both cases for a single blade channel. Loading factor performance calculated for full flow path (“360 degrees”) by ANSYS CFX is in satisfactory agreement with the stage 2 design performance. Maximum efficiency is predicted accurately by the ANSYS CFX “360 degrees” calculation. “Sector” calculation is less accurate. Further research is needed to solve the problem of performances mismatch.

The Analysis of Nonlinear Vibrations of Top-Tensioned Cantilever Pipes Conveying Pressurized Steady Two-Phase Flow under Thermal Loading

Directory of Open Access Journals (Sweden)

Adeshina S. Adegoke

2017-11-01

Full Text Available This paper studied the nonlinear vibrations of top-tensioned cantilevered pipes conveying pressurized steady two-phase flow under thermal loading. The coupled axial and transverse governing partial differential equations of motion of the system were derived based on Hamilton’s mechanics, with the centerline assumed to be extensible. Using the multiple-scale perturbation technique, natural frequencies, mode shapes, and first order approximate solutions of the steady-state response of the pipes were obtained. The multiple-scale assessment reveals that at some frequencies the system is uncoupled, while at some frequencies a 1:2 coupling exists between the axial and the transverse frequencies of the pipe. Nonlinear frequencies versus the amplitude displacement of the cantilever pipe, conveying two-phase flow at super-critical mixture velocity for the uncoupled scenario, exhibit a nonlinear hardening behavior; an increment in the void fractions of the two-phase flow results in a reduction in the pipe’s transverse vibration frequencies and the coupled amplitude of the system. However, increases in the temperature difference, pressure, and the presence of top tension were observed to increase the pipe’s transverse vibration frequencies without a significant change in the coupled amplitude of the system.

High thermal load receiving heat plate

International Nuclear Information System (INIS)

Shibutani, Jun-ichi; Shibayama, Kazuhito; Yamamoto, Keiichi; Uchida, Takaho.

1993-01-01

The present invention concerns a high thermal load heat receiving plate such as a divertor plate of a thermonuclear device. The high thermal load heat receiving plate of the present invention has a cooling performance capable of suppressing the temperature of an armour tile to less than a threshold value of the material against high thermal loads applied from plasmas. Spiral polygonal pipes are inserted in cooling pipes at a portion receiving high thermal loads in the high temperature load heat receiving plate of the present invention. Both ends of the polygonal pipes are sealed by lids. An area of the flow channel in the cooling pipes is thus reduced. Heat conductivity on the cooling surface of the cooling pipes is increased in the high thermal load heat receiving plate having such a structure. Accordingly, temperature elevation of the armour tile can be suppressed. (I.S.)

Data to support statistical modeling of instream nutrient load based on watershed attributes, southeastern United States, 2002

Science.gov (United States)

Hoos, Anne B.; Terziotti, Silvia; McMahon, Gerard; Savvas, Katerina; Tighe, Kirsten C.; Alkons-Wolinsky, Ruth

2008-01-01

This report presents and describes the digital datasets that characterize nutrient source inputs, environmental characteristics, and instream nutrient loads for the purpose of calibrating and applying a nutrient water-quality model for the southeastern United States for 2002. The model area includes all of the river basins draining to the south Atlantic and the eastern Gulf of Mexico, as well as the Tennessee River basin (referred to collectively as the SAGT area). The water-quality model SPARROW (SPAtially-Referenced Regression On Watershed attributes), developed by the U.S. Geological Survey, uses a regression equation to describe the relation between watershed attributes (predictors) and measured instream loads (response). Watershed attributes that are considered to describe nutrient input conditions and are tested in the SPARROW model for the SAGT area as source variables include atmospheric deposition, fertilizer application to farmland, manure from livestock production, permitted wastewater discharge, and land cover. Watershed and channel attributes that are considered to affect rates of nutrient transport from land to water and are tested in the SAGT SPARROW model as nutrient-transport variables include characteristics of soil, landform, climate, reach time of travel, and reservoir hydraulic loading. Datasets with estimates of each of these attributes for each individual reach or catchment in the reach-catchment network are presented in this report, along with descriptions of methods used to produce them. Measurements of nutrient water quality at stream monitoring sites from a combination of monitoring programs were used to develop observations of the response variable - mean annual nitrogen or phosphorus load - in the SPARROW regression equation. Instream load of nitrogen and phosphorus was estimated using bias-corrected log-linear regression models using the program Fluxmaster, which provides temporally detrended estimates of long-term mean load well

Three-phase power load flow with uncertainty modeling via sinusoidal membership function; Fluxo de carga trifasico com modelagem de incertezas via funcao de pertinencia sinusoidal

Energy Technology Data Exchange (ETDEWEB)

Cavalcante, Patricia L.; Murari, Carlos Alberto F.; Salas, Silvio S. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Fac. de Engenharia Eletrica e de Computacao], Emails: plc@dsee.fee.unicamp.br, murari@dsee.fee.unicamp.br, ssegura@dsee.fee.unicamp.br

2009-07-01

During the development of models for power systems, the researchers aim always to get results compatible with reality, and in this research it was our objective consider that some electric system variables are not deterministic, i e there is imprecision or variations, for example, on the loads. In this study, imprecise variables are represented as fuzzy numbers (the bell shape) and is presented a methodology for analysis of electrical networks of distribution through a specialist three-phase load flow that incorporates fuzzy sets and mathematical operations based on fuzzy logic. The results confirm the good performance of this new method.

Transient Side Load Analysis of Out-of-Round Film-Cooled Nozzle Extensions

Science.gov (United States)

Wang, Ten-See; Lin, Jeff; Ruf, Joe; Guidos, Mike

2012-01-01

There was interest in understanding the impact of out-of-round nozzle extension on the nozzle side load during transient startup operations. The out-of-round nozzle extension could be the result of asymmetric internal stresses, deformation induced by previous tests, and asymmetric loads induced by hardware attached to the nozzle. The objective of this study was therefore to computationally investigate the effect of out-of-round nozzle extension on the nozzle side loads during an engine startup transient. The rocket engine studied encompasses a regeneratively cooled chamber and nozzle, along with a film cooled nozzle extension. The computational methodology is based on an unstructured-grid, pressure-based computational fluid dynamics formulation, and transient inlet boundary flow properties derived from an engine system simulation. Six three-dimensional cases were performed with the out-of-roundness achieved by three different degrees of ovalization, elongated on lateral y and z axes: one slightly out-of-round, one more out-of-round, and one significantly out-of-round. The results show that the separation line jump was the primary source of the peak side loads. Comparing to the peak side load of the perfectly round nozzle, the peak side loads increased for the slightly and more ovalized nozzle extensions, and either increased or decreased for the two significantly ovalized nozzle extensions. A theory based on the counteraction of the flow destabilizing effect of an exacerbated asymmetrical flow caused by a lower degree of ovalization, and the flow stabilizing effect of a more symmetrical flow, created also by ovalization, is presented to explain the observations obtained in this effort.

Turbulence and turbulence-generated structural loading in wind turbine clusters

DEFF Research Database (Denmark)

Frandsen, Sten Tronæs

2007-01-01

of the model is that it became part of the Danish standard for wind turbine design DS 472 (2001) in August 2001 and it is part of the corresponding international standard, IEC61400-1 (2005). Also, extreme loading under normal operation for wake conditions and the efficiency of very large wind farms......Turbulence - in terms of standard deviation of wind speed fluctuations - and other flow characteristics are different in the interior of wind farms relative to the free flow and action must be taken to ensure sufficient structural sustainability of the wind turbines exposed to “wind farm flow......”. The standard deviation of wind speed fluctuations is a known key parameter for both extreme- and fatigue loading, and it is argued and found to be justified that a model for change in turbulence intensity alone may account for increased fatigue loading in wind farms. Changes in scale of turbulence...

Cold Flow Determination of the Internal Flow Environment Around the Submerged TVC Nozzle for the Space Shuttle SRM

Science.gov (United States)

Whitesides, R. H.; Ghosh, A.; Jenkins, S. L.; Bacchus, D. L.

1989-01-01

A series of subscale cold flow tests was performed to quantify the gas flow characteristics at the aft end of the Space Shuttle Solid Rocket Motor. This information was used to support the analyses of the redesigned nozzle/case joint. A portion of the thermal loads at the joint are due to the circumferential velocities and pressure gradients caused primarily by the gimbaling of the submerged nose TVC nozzle. When the nozzle centerline is vectored with respect to the motor centerline, asymmetries are set up in the flow field under the submerged nozzle and immediately adjacent to the nozzle/case joint. Specific program objectives included: determination of the effects of nozzle gimbal angle and propellant geometry on the circumferential flow field; measurement of the static pressure and gas velocities in the vicinity of the nozzle/case joint; use of scaling laws to apply the subscale cold flow data to the full scale SRM; and generation of data for use in validation of 3-D computational fluid dynamic, CFD, models of the SRM flow field. These tests were conducted in the NASA Marshall Space Flight Center Airflow Facility with a 7.5 percent scale model of the aft segment of the SRM. Static and dynamic pressures were measured in the model to quantify the flow field. Oil flow data was also acquired to obtain qualitative visual descriptions of the flow field. Nozzle gimbal angles of 0, 3.5, and 7 deg were used with propellant grain configurations corresponding to motor burn times of 0, 9, 19, and 114 seconds. This experimental program was successful in generating velocity and pressure gradient data for the flow field around the submerged nose nozzle of the Space Shuttle SRM at various burn times and gimbal angles. The nature of the flow field adjacent to the nozzle/case joint was determined with oil droplet streaks, and the velocity and pressure gradients were quantified with pitot probes and wall static pressure measurements. The data was applied to the full scale SRM thru

SAFSIM theory manual: A computer program for the engineering simulation of flow systems

Energy Technology Data Exchange (ETDEWEB)

Dobranich, D.

1993-12-01

SAFSIM (System Analysis Flow SIMulator) is a FORTRAN computer program for simulating the integrated performance of complex flow systems. SAFSIM provides sufficient versatility to allow the engineering simulation of almost any system, from a backyard sprinkler system to a clustered nuclear reactor propulsion system. In addition to versatility, speed and robustness are primary SAFSIM development goals. SAFSIM contains three basic physics modules: (1) a fluid mechanics module with flow network capability; (2) a structure heat transfer module with multiple convection and radiation exchange surface capability; and (3) a point reactor dynamics module with reactivity feedback and decay heat capability. Any or all of the physics modules can be implemented, as the problem dictates. SAFSIM can be used for compressible and incompressible, single-phase, multicomponent flow systems. Both the fluid mechanics and structure heat transfer modules employ a one-dimensional finite element modeling approach. This document contains a description of the theory incorporated in SAFSIM, including the governing equations, the numerical methods, and the overall system solution strategies.

Second Order Cone Programming (SOCP) Relaxation Based Optimal Power Flow with Hybrid VSC-HVDC Transmission and Active Distribution Networks

DEFF Research Database (Denmark)

Ding, Tao; Li, Cheng; Yang, Yongheng

2017-01-01

The detailed topology of renewable resource bases may have the impact on the optimal power flow of the VSC-HVDC transmission network. To address this issue, this paper develops an optimal power flow with the hybrid VSC-HVDC transmission and active distribution networks to optimally schedule...... the generation output and voltage regulation of both networks, which leads to a non-convex programming model. Furthermore, the non-convex power flow equations are based on the Second Order Cone Programming (SOCP) relaxation approach. Thus, the proposed model can be relaxed to a SOCP that can be tractably solved...

Stone Stability in Non-uniform Flow

NARCIS (Netherlands)

Hoan, N.T.; Stive, M.J.F.; Booij, R.; Hofland, B.; Verhagen, H.J.

2011-01-01

This paper presents the results of an experimental study on stone stability under nonuniform turbulent flow, in particular expanding flow. Detailed measurements of both flow and turbulence and the bed stability are described. Than various manners of quantifying the hydraulic loads exerted on the

High-uranium-loaded U3O8-Al fuel element development program [contributed by N.M. Martin, ORNL

International Nuclear Information System (INIS)

Martin, M.M.

1993-01-01

The High-Uranium-Loaded U 3 O 8 -Al Fuel Element Development Program supports Argonne National Laboratory efforts to develop high-uranium-density research and test reactor fuel to accommodate use of low-uranium enrichment. The goal is to fuel most research and test reactors with uranium of less than 20% enrichment for the purpose of lowering the potential for diversion of highly-enriched material for nonpeaceful usages. The specific objective of the program is to develop the technological and engineering data base for U 3 O 8 -Al plate-type fuel elements of maximal uranium content to the point of vendor qualification for full scale fabrication on a production basis. A program and management plan that details the organization, supporting objectives, schedule, and budget is in place and preparation for fuel and irradiation studies is under way. The current programming envisions a program of about four years duration for an estimated cost of about two million dollars. During the decades of the fifties and sixties, developments at Oak Ridge National Laboratory led to the use of U 3 O 8 -Al plate-type fuel elements in the High Flux Isotope Reactor, Oak Ridge Research Reactor, Puerto Rico Nuclear Center Reactor, and the High Flux Beam Reactor. Most of the developmental information however applies only up to a uranium concentration of about 55 wt % (about 35 vol % U 3 O 8 ). The technical issues that must be addressed to further increase the uranium loading beyond 55 wt % involve plate fabrication phenomena of voids and dogboning, fuel behavior under long irradiation, and potential for the thermite reaction between U 3 O 8 and aluminum. (author)

MININR: a geochemical computer program for inclusion in water flow models - an application study

Energy Technology Data Exchange (ETDEWEB)

Felmy, A.R.; Reisenauer, A.E.; Zachara, J.M.; Gee, G.W.

1984-02-01

MININR is a reduced form of the computer program MINTEQ which calculates equilibrium precipitation/dissolution of solid phases, aqueous speciation, adsorption, and gas phase equilibrium. The user-oriented features in MINTEQ were removed to reduce the size and increase the computational speed. MININR closely resembles the MINEQL computer program developed by Westall (1976). The main differences between MININR and MINEQL involve modifications to accept an initial starting mass of solid and necessary changes for linking with a water flow model. MININR in combination with a simple water flow model which considers only dilution was applied to a laboratory column packed with retorted oil shale and percolated with distilled water. Experimental and preliminary model simulation results are presented for the constituents K/sup +/, Na/sup +/, SO/sub 4//sup 2 -/, Mg/sup 2 +/, Ca/sup 2 +/, CO/sub 3//sup 2 -/ and pH.

Turbulence and turbulence-generated structural loading in wind turbine clusters

Energy Technology Data Exchange (ETDEWEB)

Frandsen, Sten

2007-01-15

Turbulence, in terms of standard deviation of wind speed fluctuations, and other flow characteristics are different in the interior of wind farms relative to the free flow and action must be taken to ensure sufficient structural sustainability of the wind turbines exposed to 'wind farm flow'. The standard deviation of wind speed fluctuations is a known key parameter for both extreme- and fatigue loading, and it is argued and found to be justified that a model for change in turbulence intensity alone may account for increased fatigue loading in wind farms. Changes in scale of turbulence and horizontal flow-shear also influence the dynamic response and thus fatigue loading. However, these parameters are typically negatively or positively correlated with the standard deviation of wind speed fluctuations, which therefore can, if need be, represent these other variables. Thus, models for spatially averaged turbulence intensity inside the wind farm and direct-wake turbulence intensity are being devised and a method to combine the different load situations is proposed. The combination of the load cases implies a weighting method involving the slope of the considered material's Woehler curve. In the context, this is novel and necessary to avoid excessive safety for fatigue estimation of the structure's steel components, and non-conservatism for fibreglass components. The proposed model offers significant reductions in computational efforts in the design process. The status for the implementation of the model is that it became part of the Danish standard for wind turbine design DS 472 (2001) in August 2001 and it is part of the corresponding international standard, IEC61400-1 (2005). Also, extreme loading under normal operation for wake conditions and the efficiency of very large wind farms are discussed. (au)

LabVIEW Serial Driver Software for an Electronic Load

Science.gov (United States)

Scullin, Vincent; Garcia, Christopher

2003-01-01

A LabVIEW-language computer program enables monitoring and control of a Transistor Devices, Inc., Dynaload WCL232 (or equivalent) electronic load via an RS-232 serial communication link between the electronic load and a remote personal computer. (The electronic load can operate at constant voltage, current, power consumption, or resistance.) The program generates a graphical user interface (GUI) at the computer that looks and acts like the front panel of the electronic load. Once the electronic load has been placed in remote-control mode, this program first queries the electronic load for the present values of all its operational and limit settings, and then drops into a cycle in which it reports the instantaneous voltage, current, and power values in displays that resemble those on the electronic load while monitoring the GUI images of pushbuttons for control actions by the user. By means of the pushbutton images and associated prompts, the user can perform such operations as changing limit values, the operating mode, or the set point. The benefit of this software is that it relieves the user of the need to learn one method for operating the electronic load locally and another method for operating it remotely via a personal computer.

Improvement of daily load-following operation for boiling water reactors

International Nuclear Information System (INIS)

Kiguchi, Takashi; Kurihara, Kunitoshi; Sakurai, Mikio; Joge, Toshio; Asami, Kazuo.

1980-01-01

Recently, with the increase of the proportion of nuclear power generation to the total amount of power generation of electric power systems, the needs of daily load-following operation of nuclear power stations have heightened, accordingly the study on the method of daily load-following operation has been carried out for BWRs. In this study, by the combined use of the flow rate control of core coolnat being operated easily and the operation of control rods, the BWR system with the daily load-following performance of 100% power output in daytime and 50% power output at night was the target of development. For the purpose, the change of core characteristics during load-following was grasped analytically, and the range of load change was investigated. At the same time, as the first stage of developing operation control and monitoring system, the reactor output-adjusting device which makes generator output automatically follow the target load change pattern by the flow rate control of core coolnat, and the equipment for monitoring core performance on line were developed. The analysis of the method of daily load-following operation in present-day BWRs, the study on the improvement of load-following operation performance, the reactor output-adjusting device are described. (Kako, I.)

Experimental studies of interaction mechanisms and phase transport processes in two-phase flow (NOVA program)

International Nuclear Information System (INIS)

Sauter, H.; Meyder, R.; Philipp, P.; Samstag, M.

1995-01-01

The NOVA program was continued with turbulent, vertical, upward two-phase flow experiments. The development of a local gas distribution along the test section was visualized by X-ray tomography. (orig.)

Learning Based Approach for Optimal Clustering of Distributed Program's Call Flow Graph

Science.gov (United States)

Abofathi, Yousef; Zarei, Bager; Parsa, Saeed

Optimal clustering of call flow graph for reaching maximum concurrency in execution of distributable components is one of the NP-Complete problems. Learning automatas (LAs) are search tools which are used for solving many NP-Complete problems. In this paper a learning based algorithm is proposed to optimal clustering of call flow graph and appropriate distributing of programs in network level. The algorithm uses learning feature of LAs to search in state space. It has been shown that the speed of reaching to solution increases remarkably using LA in search process, and it also prevents algorithm from being trapped in local minimums. Experimental results show the superiority of proposed algorithm over others.

Enhancement of glomerular filtration rate and renal plasma flow by oral glucose load in well controlled insulin-dependent diabetics

DEFF Research Database (Denmark)

Sandahl Christiansen, J; Christensen, C K; Hermansen, K

1986-01-01

Glomerular filtration rate (GFR) and renal plasma flow (RPF) were measured in 27 patients with uncomplicated insulin-dependent diabetes (IDDM) before and after an oral glucose load of 1.1 g glucose/kg body wt. In the 18 patients showing near-normoglycaemia (blood glucose less than or equal to 8....... No changes in blood pressure or urinary albumin excretion rates took place in either group. The reduction in plasma protein and in plasma growth hormone concentration were similar in the two groups. No change was seen in plasma arginine vasopressin concentration. There was no difference in the qualitative...

Part-load pumping operation, control and behaviour

International Nuclear Information System (INIS)

1988-01-01

Twenty one papers are printed. Their main concern is with pump performance under abnormal operating conditions or when operating at part-load. The effect of part-load operation on pump performance, pump internal flow and pump cavitation and noise were considered. The pumps considered are used in a variety of situations and some case studies were discussed. One paper about part-load operation of the boiler pumps for French pressurized water reactors and one paper on pressure pulsations of centrifugal pumps at very low flowrate, are indexed separately. (U.K.)

Acoustic programming in step-split-flow lateral-transport thin fractionation.

Science.gov (United States)

Ratier, Claire; Hoyos, Mauricio

2010-02-15

We propose a new separation scheme for micrometer-sized particles combining acoustic forces and gravitational field in split-flow lateral-transport thin (SPLITT)-like fractionation channels. Acoustic forces are generated by ultrasonic standing waves set up in the channel thickness. We report on the separation of latex particles of two different sizes in a preliminary experiment using this proposed hydrodynamic acoustic sorter, HAS. Total binary separation of 5 and 10 microm diameter particles has been achieved. Numerical simulations of trajectories of particles flowing through a step-SPLITT under the conditions which combine acoustic standing waves and gravity show a very good agreement with the experiment. Calculations in order to compare separations obtained by the acoustic programming s-SPLITT fractionation and the conventional SPLITT fractionation show that the improvement in separation time is around 1 order of magnitude and could still be improved; this is the major finding of this work. This separation technique can be extended to biomimetic particles and blood cells.

The Influence of Proposed Repository Thermal Load on Multiphase Flow and Heat Transfer in the Unsaturated Zone of Yucca Mountain

International Nuclear Information System (INIS)

Wu, Y.-S.; Mukhopadhyay, Sumit; Zhang, Keni; Bodvarsson, G.S.

2006-01-01

This paper investigates the impact of proposed repository thermal-loading on mountain-scale flow and heat transfer in the unsaturated fractured rock of Yucca Mountain, Nevada. In this context, a model has been developed to study the coupled thermal-hydrological (TH)processes at the scale of the entire Yucca Mountain. This mountain-scale TH model implements the current geological framework and hydrogeological conceptual models, and incorporates the latest rock thermal and hydrological properties. The TH model consists of a two-dimensional north-south vertical cross section across the entire unsaturated zone model domain and uses refined meshes near and around the proposed repository block, based on the current repository design, drift layout, thermal loading scenario, and estimated current and future climatic conditions. The model simulations provide insights into thermally affected liquid saturation, gas- and liquid-phase fluxes, and elevated water and rock temperature, which in turn allow modelers to predict the changes in water flux driven by evaporation/condensation processes, and drainage between drifts

Continuous 'Passive' Registration of Non-Point Contaminant Loads Via Agricultural Subsurface Drain Tubes

Science.gov (United States)

Rozemeijer, J.; Jansen, S.; de Jonge, H.; Lindblad Vendelboe, A.

2014-12-01

Considering their crucial role in water and solute transport, enhanced monitoring and modeling of agricultural subsurface tube drain systems is important for adequate water quality management. For example, previous work in lowland agricultural catchments has shown that subsurface tube drain effluent contributed up to 80% of the annual discharge and 90-92% of the annual NO3 loads from agricultural fields towards the surface water. However, existing monitoring techniques for flow and contaminant loads from tube drains are expensive and labor-intensive. Therefore, despite the unambiguous relevance of this transport route, tube drain monitoring data are scarce. The presented study aimed developing a cheap, simple, and robust method to monitor loads from tube drains. We are now ready to introduce the Flowcap that can be attached to the outlet of tube drains and is capable of registering total flow, contaminant loads, and flow-averaged concentrations. The Flowcap builds on the existing SorbiCells, a modern passive sampling technique that measures average concentrations over longer periods of time (days to months) for various substances. By mounting SorbiCells in our Flowcap, a flow-proportional part of the drain effluent is sampled from the main stream. Laboratory testing yielded good linear relations (R-squared of 0.98) between drainage flow rates and sampling rates. The Flowcap was tested in practice for measuring NO3 loads from two agricultural fields and one glasshouse in the Netherlands. The Flowcap registers contaminant loads from tube drains without any need for housing, electricity, or maintenance. This enables large-scale monitoring of non-point contaminant loads via tube drains, which would facilitate the improvement of contaminant transport models and would yield valuable information for the selection and evaluation of mitigation options to improve water quality.

Response to severe changes of load on the reactor system of nuclear ship Mutsu

International Nuclear Information System (INIS)

Ishida, Toshihisa; Kusunoki, Tsuyoshi; Ochiai, Masa-aki; Tanaka, Yoshimi; Yao, Toshiaki; Inoue, Kimio.

1993-01-01

The response of the nuclear power system of N.S. Mutsu to severe changes of load have been studied from records taken during the power-raising tests performed on the ship in 1990. The records examined were those involving the most severe load changes foreseen for marine reactors: (a) sharp load increase with total steam flow raised from 25 to 70 % rated full flow in 13s, (b) crash astern maneuver with the position of propulsion turbine command handle changed-taking several seconds-from cruising ahead to STOP, and after about 50s, further changed-taking 30s-to bring the astern propulsion turbine to full speed-to consume approximately 60 % rated total steam flow and (c) turbine trip with the ahead turbine intentionally tripped when operating at roughly 100 % rated total steam flow. The foregoing records from load changes-of severity beyond what is foreseen for land-based reactors-proved that the Mutsu reactor is capable of responding smoothly and securely to such severe load changes. These load changes occasioned relatively large mismatches between reactor power supply and steam flow demand, but with notable freedom from any conspicuous overshooting or hunting of the reactor power. This performance can be attributed to (a) correct functioning of the automatic power control system, (b) effective contribution of the self-regulating reactor control property deriving from the large negative feedback between moderator temperature and reactivity, and (c) the ample inventories of coolant in the primary and secondary loops. The responses to load change are discussed covering those relevant to (a) reactor power, (b) primary loop pressure, and (c) steam generator pressure, with particular reference to the differences seen in response to mild and to severe load changes. (author)

Electric utility load management: rational use of energy program pilot study

Energy Technology Data Exchange (ETDEWEB)

1977-08-01

In recognition of the role that load management can play in ensuring that the growing demand for electricity is met in a cost- and energy-efficient manner, in mid-1974, the NATO Committee on the Challenges of Modern Society sponsored all three meetings to provide a forum for representatives of U.S. and European utilities to exchange views and experiences on the various aspects of load management. It was the consensus of representatives at the meetings that three overall approaches offer significant opportunities for achieving improved load management: development of marginal-cost rate structures; power pooling and energy storage by utilities; and efforts by consumers. Industrial consumers can assist electric utilities in their efforts to level system loads through three important methods: interruptible power and deferred load control; peak self-generation; and shifts in operating schedules. Residential/commercial consumers also have an important role to play by managing both their electric heating load (through the interruption of direct-resistance heating and the storage of heat) and their air conditioning load. In response to the interest expressed by the participants in the CCMS conferences, the U.S. and several European governments, national electric utility industry organizations, state public utility commissions, and many individual utilities have undertaken R and D projects to investigate and test various aspects of these three approaches to load management. This report describes the projects that were presented by the utility representatives.

Metals transport in the Sacramento River, California, 1996-1997; Volume 2: Interpretation of metal loads

Science.gov (United States)

Alpers, Charles N.; Antweiler, Ronald C.; Taylor, Howard E.; Dileanis, Peter D.; Domagalski, Joseph L.

2000-01-01

percent. During irrigation drainage season from rice fields (May-June 1997) loads were cadmium, 53 percent; copper, 42 percent; lead, 20 percent; and zinc, 75 percent. These estimates must be qualified by the following factors: (1) metal loads at Colusa in December 1996 and at Verona in May-June 1997 generally exceeded those determined at Freeport during those sampling periods. Therefore, the above percentages represent maximum estimates of the apparent total proportion of metals from mineralized areas upstream of Keswick Dam; and (2) for logistics reasons, the Sacramento River was sampled at Tower Bridge instead of at Freeport during January 1997.Available data suggest that trace metal loads from agricultural drainage may be significant during certain flow conditions in areas where metals such as copper and zinc are added as agricultural amendments. Copper loads for sampling periods in July and September 1996 and in May-June 1997 show increases of dissolved and colloidal copper and in colloidal zinc between Colusa and Verona, the reach of the Sacramento River along which the Colusa Basin Drain, the Sacramento Slough, and other agricultural return flows are tributaries. Monthly sampling of these two agricultural drains by the USGS National Water-Quality Assessment Program shows seasonal variations in metal concentrations, reaching maximum concentrations of 4 to 6 micrograms per liter in "dissolved" (0.45-micrometer filtrate) copper concentrations in May 1996, December 1996, and June 1997. The total (dissolved plus colloidal) load of copper from the Colusa Basin Drain in June 1997 was 18 kilograms per day, whereas the copper load in Spring Creek, which drains the inactive mines on Iron Mountain, was 20 kilograms per day during the same sampling period. For comparison, during the January 1997 flood, the copper load in Spring Creek was about 1,100 kilograms per day and the copper load in the Yolo Bypass was about 7,300 kilograms per day. The data clearly indicate that most

Optimal Power Flow in Multiphase Radial Networks with Delta Connections: Preprint

Energy Technology Data Exchange (ETDEWEB)

Zhao, Changhong [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Dall-Anese, Emiliano [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Low, Steven H. [California Institute of Technology

2017-11-27

This paper focuses on multiphase radial distribution networks with mixed wye and delta connections, and proposes a semidefinite relaxation of the AC optimal power flow (OPF) problem. Two multiphase power-flow models are developed to facilitate the integration of delta-connected generation units/loads in the OPF problem. The first model extends traditional branch flow models - and it is referred to as extended branch flow model (EBFM). The second model leverages a linear relationship between per-phase power injections and delta connections, which holds under a balanced voltage approximation (BVA). Based on these models, pertinent OPF problems are formulated and relaxed to semidefinite programs (SDPs). Numerical studies on IEEE test feeders show that SDP relaxations can be solved efficiently by a generic optimization solver. Numerical evidences indicate that solving the resultant SDP under BVA is faster than under EBFM. Moreover, both SDP solutions are numerically exact with respect to voltages and branch flows. It is also shown that the SDP solution under BVA has a small optimality gap, while the BVA model is accurate in the sense that it reflects actual system voltages.

Enhancement of glomerular filtration rate and renal plasma flow by oral glucose load in well controlled insulin-dependent diabetics

DEFF Research Database (Denmark)

Sandahl Christiansen, J; Christensen, C K; Hermansen, K

1986-01-01

Glomerular filtration rate (GFR) and renal plasma flow (RPF) were measured in 27 patients with uncomplicated insulin-dependent diabetes (IDDM) before and after an oral glucose load of 1.1 g glucose/kg body wt. In the 18 patients showing near-normoglycaemia (blood glucose less than or equal to 8...... mmol/l) before the glucose challenge the increase in blood glucose from 4.2 +/- 1.7 to 15.2 +/- 2.3 mmol/l was accompanied by an enhancement of GFR from 128 +/- 15 to 132 +/- 14 ml/min X 1.73 m2 (2p = 0.030) and of RPF from 534 +/- 116 to 562 +/- 105 ml/min X 1.73 m2 (2p = 0.023). By contrast oral...... glucose load to the nine patients with hyperglycaemia (greater than 8 mmol/l) during baseline conditions raising blood glucose from 11.9 +/- 2.0 to 19.6 +/- 1.5 mmol/l was accompanied by a reduction in GFR from 149 +/- 15 to 139 +/- 9 ml/min X 1.73 m2 (2p less than 0.001) while RPF was unchanged...

Petri Nets Based Modelling of Control Flow for Memory-Aid Interactive Programs in Telemedicine

CERN Document Server

Khoromskaia, V K

2004-01-01

Petri Nets (PN) based modelling of the control flow for the interactive memory assistance programs designed for personal pocket computers and having special requirements for robustness is considered. The proposed concept allows one to elaborate the programs which can give users a variety of possibilities for a day-time planning in the presence of environmental and time restrictions. First, a PN model for a known simple algorithm is constructed and analyzed using the corresponding state equations and incidence matrix. Then a PN graph for a complicated algorithm with overlapping actions and choice possibilities is designed, supplemented by an example of its analysis. Dynamic behaviour of this graph is tested by tracing of all possible paths of the flow of control using the PN simulator. It is shown that PN based modelling provides reliably predictable performance of interactive algorithms with branched structures and concurrency requirements.

Postexercise blood flow restriction does not enhance muscle hypertrophy induced by multiple-set high-load resistance exercise.

Science.gov (United States)

Madarame, Haruhiko; Nakada, Satoshi; Ohta, Takahisa; Ishii, Naokata

2018-05-01

To test the applicability of postexercise blood flow restriction (PEBFR) in practical training programmes, we investigated whether PEBFR enhances muscle hypertrophy induced by multiple-set high-load resistance exercise (RE). Seven men completed an eight-week RE programme for knee extensor muscles. Employing a within-subject design, one leg was subjected to RE + PEBFR, whereas contralateral leg to RE only. On each exercise session, participants performed three sets of unilateral knee extension exercise at approximately 70% of their one-repetition maximum for RE leg first, and then performed three sets for RE + PEBFR leg. Immediately after completion of the third set, the proximal portion of the RE + PEBFR leg was compressed with an air-pressure cuff for 5 min at a pressure ranging from 100 to 150 mmHg. If participants could perform 10 repetitions for three sets in two consecutive exercise sessions, the work load was increased by 5% at the next exercise session. Muscle thickness and strength of knee extensor muscles were measured before and after the eight-week training period and after the subsequent eight-week detraining period. There was a main effect of time but no condition × time interaction or main effect of condition for muscle thickness and strength. Both muscle thickness and strength increased after the training period independent of the condition. This result suggests that PEBFR would not be an effective training method at least in an early phase of adaptation to high-load resistance exercise. © 2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

Load Asymmetry Observed During Orion Main Parachute Inflation

Science.gov (United States)

Morris, Aaron L.; Taylor, Thomas; Olson, Leah

2011-01-01

The Crew Exploration Vehicle Parachute Assembly System (CPAS) has flight tested the first two generations of the Orion parachute program. Three of the second generation tests instrumented the dispersion bridles of the Main parachute with a Tension Measuring System. The goal of this load measurement was to better understand load asymmetry during the inflation process of a cluster of Main parachutes. The CPAS Main parachutes exhibit inflations that are much less symmetric than current parachute literature and design guides would indicate. This paper will examine loads data gathered on three cluster tests, quantify the degree of asymmetry observed, and contrast the results with published design guides. Additionally, the measured loads data will be correlated with videos of the parachute inflation to make inferences about the shape of the parachute and the relative load asymmetry. The goal of this inquiry and test program is to open a dialogue regarding asymmetrical parachute inflation load factors.

Load Estimation from Natural input Modal Analysis

DEFF Research Database (Denmark)

Aenlle, Manuel López; Brincker, Rune; Canteli, Alfonso Fernández

2005-01-01

One application of Natural Input Modal Analysis consists in estimating the unknown load acting on structures such as wind loads, wave loads, traffic loads, etc. In this paper, a procedure to determine loading from a truncated modal model, as well as the results of an experimental testing programme...... estimation. In the experimental program a small structure subjected to vibration was used to estimate the loading from the measurements and the experimental modal space. The modal parameters were estimated by Natural Input Modal Analysis and the scaling factors of the mode shapes obtained by the mass change...

Modeling of Compressible Flow with Friction and Heat Transfer Using the Generalized Fluid System Simulation Program (GFSSP)

Science.gov (United States)

Bandyopadhyay, Alak; Majumdar, Alok

2007-01-01

The present paper describes the verification and validation of a quasi one-dimensional pressure based finite volume algorithm, implemented in Generalized Fluid System Simulation Program (GFSSP), for predicting compressible flow with friction, heat transfer and area change. The numerical predictions were compared with two classical solutions of compressible flow, i.e. Fanno and Rayleigh flow. Fanno flow provides an analytical solution of compressible flow in a long slender pipe where incoming subsonic flow can be choked due to friction. On the other hand, Raleigh flow provides analytical solution of frictionless compressible flow with heat transfer where incoming subsonic flow can be choked at the outlet boundary with heat addition to the control volume. Nonuniform grid distribution improves the accuracy of numerical prediction. A benchmark numerical solution of compressible flow in a converging-diverging nozzle with friction and heat transfer has been developed to verify GFSSP's numerical predictions. The numerical predictions compare favorably in all cases.

Simulation model for wind energy storage systems. Volume III. Program descriptions. [SIMWEST CODE

Energy Technology Data Exchange (ETDEWEB)

Warren, A.W.; Edsinger, R.W.; Burroughs, J.D.

1977-08-01

The effort developed a comprehensive computer program for the modeling of wind energy/storage systems utilizing any combination of five types of storage (pumped hydro, battery, thermal, flywheel and pneumatic). An acronym for the program is SIMWEST (Simulation Model for Wind Energy Storage). The level of detail of SIMWEST is consistent with a role of evaluating the economic feasibility as well as the general performance of wind energy systems. The software package consists of two basic programs and a library of system, environmental, and load components. Volume III, the SIMWEST program description contains program descriptions, flow charts and program listings for the SIMWEST Model Generation Program, the Simulation program, the File Maintenance program and the Printer Plotter program. Volume III generally would not be required by SIMWEST user.

Phloem loading--not metaphysical, only complex: towards a unified model of phloem loading.

Science.gov (United States)

Komor, E; Orlich, G; Weig, A; Köckenberger, W

1996-08-01

level in most organs of the seedling and throughout the germination period. Leaves of adult Ricinus have significantly lower levels of this transcript. Recirculation of excess, phloem-delivered solutes from the sink back to the source is shown not only to be a common feature of long-distance transport, but the only way that an imbalance between supply to and consumption of nutrients in the sink can be adjusted in the source. It is a pathway by which sink activity regulates phloem loading. Non-invasive NMR imaging revealed the flow rates and flow speeds in phloem and xylem in the intact seedling and proved directly the existence of an internal circulating solution flow. A unified model of phloem loading is proposed, based on a pump-and-leak model, where active sucrose carriers (and other carriers) accumulate solutes in the sieve tubes with a concomitant build-up of pressure resulting in mass flow. Plasmodesmata are leaks (as are the transport carriers, too), slowing down the transport rate, but they also serve as diffusion channels for substances which are produced in the neighbouring cell. Therefore, compounds, which are not made in the sieve tubes themselves are translocated together with the bulk solution of sieve tube sap.

Inflow measurements from blade-mounted flow sensors: Flow analysis, application and aeroelastic response

DEFF Research Database (Denmark)

Pedersen, Mads Mølgaard

-mounted flow sensor, BMFS, e.g. a five-hole pitot tube, which has been used in several research experiments over the last 30 years. The BMFS measured flow velocity is, however, located inside the induction zone and thereby influenced by the aerodynamic properties, the control strategy and the operational......The power and load performance of wind turbines are both crucial for the development and expansion of wind energy. The power and loads are highly dependent on the inflow conditions, which can be measured using different types of sensors mounted on nearby met masts, on the nacelle, at the spinner...... or at the blade. Each combination of sensor type and mounting position has advantages and shortcomings. To characterise the inflow that results in high and low fatigue loads, information about the temporal and spatial variations within the rotor area is required. This information can be obtained from a blade...

pygrametl: A Powerful Programming Framework for Extract-Transform-Load Programmers

DEFF Research Database (Denmark)

Thomsen, Christian; Pedersen, Torben Bach

2009-01-01

Extract–Transform–Load (ETL) processes are used for extracting data, transforming it and loading it into data warehouses (DWs). Many tools for creating ETL processes exist. The dominating tools all use graphical user interfaces (GUIs) where the developer visu- ally defines the data flow...

Optimisation of load control

International Nuclear Information System (INIS)

Koponen, P.

1998-01-01

Electricity cannot be stored in large quantities. That is why the electricity supply and consumption are always almost equal in large power supply systems. If this balance were disturbed beyond stability, the system or a part of it would collapse until a new stable equilibrium is reached. The balance between supply and consumption is mainly maintained by controlling the power production, but also the electricity consumption or, in other words, the load is controlled. Controlling the load of the power supply system is important, if easily controllable power production capacity is limited. Temporary shortage of capacity causes high peaks in the energy price in the electricity market. Load control either reduces the electricity consumption during peak consumption and peak price or moves electricity consumption to some other time. The project Optimisation of Load Control is a part of the EDISON research program for distribution automation. The following areas were studied: Optimization of space heating and ventilation, when electricity price is time variable, load control model in power purchase optimization, optimization of direct load control sequences, interaction between load control optimization and power purchase optimization, literature on load control, optimization methods and field tests and response models of direct load control and the effects of the electricity market deregulation on load control. An overview of the main results is given in this chapter

Optimisation of load control

Energy Technology Data Exchange (ETDEWEB)

Koponen, P [VTT Energy, Espoo (Finland)

1998-08-01

Electricity cannot be stored in large quantities. That is why the electricity supply and consumption are always almost equal in large power supply systems. If this balance were disturbed beyond stability, the system or a part of it would collapse until a new stable equilibrium is reached. The balance between supply and consumption is mainly maintained by controlling the power production, but also the electricity consumption or, in other words, the load is controlled. Controlling the load of the power supply system is important, if easily controllable power production capacity is limited. Temporary shortage of capacity causes high peaks in the energy price in the electricity market. Load control either reduces the electricity consumption during peak consumption and peak price or moves electricity consumption to some other time. The project Optimisation of Load Control is a part of the EDISON research program for distribution automation. The following areas were studied: Optimization of space heating and ventilation, when electricity price is time variable, load control model in power purchase optimization, optimization of direct load control sequences, interaction between load control optimization and power purchase optimization, literature on load control, optimization methods and field tests and response models of direct load control and the effects of the electricity market deregulation on load control. An overview of the main results is given in this chapter

Estimation of metal pollutant loads from Nuclear and Energy Research Institute (Brazil)

Energy Technology Data Exchange (ETDEWEB)

Marques, Joyce R.; Monteiro, Lucilena R.; Soares, Sabrina M.V.; Stellato, Thamiris B.; Silva, Tatiane B.S.C.; Silva, Douglas B. da; Faustino, Mainara G.; Pires, Maria A.F.; Cotrim, Marycel E.B., E-mail: joyce.marques@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2015-07-01

According to National Environmental Council's (CONAMA) Resolution 357/05, pollutant load can be defined as the amount of a particular pollutant released in receiving water body; it is commonly expressed in a mass-time ratio. As specified in CONAMA's Resolution 430/11, the responsible for the pollutant source must present the Pollutant Load Declaration to environmental authorities. However, pollutant load knowledge is also important to the water quality maintenance and its environmental rating that must be kept to meet the requirements of the most restrictive use. In the control of metals releases is also important due public health matters, since they can cause harmful environmental contamination and major public health issues. Therefore this work aims to present the estimated metal pollutant load released by Nuclear and Energy Research Institute (IPEN/CNEN - Brazil), between 2013 and 2014. Results of cadmium, lead, copper, chromium, zinc, nickel, manganese, iron, barium, silver, boron and tin in composite samples (weekly) via Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) and bromide (Br-) released as a tracer, to measure the wastewater flow were used to estimate IPEN's Metal Pollutant load. This study is part of the environmental assessment Program at IPEN, instituted since 2006 to the attendance of the current environmental legislation (CONAMA's Resolution 430/11, Article 19-A of State Decree 8.468/76 and State Decree 15.425/80). (author)

On the way to reliable aeroelastic load simulation on VAWT's

DEFF Research Database (Denmark)

Larsen, Torben J.; Aagaard Madsen, Helge

2013-01-01

In this paper a method for an implementation of a 2D actuator cylinder flow model of an Vertical Axis Wind Turbine (VAWT) is presented. The model is implemented in a full aeroelastic code including consideration of structural dynamics, dynamic inflow, tower shadow and dynamic stall, which is needed...... for a full load analysis relating to eg. certification of a VAWT turbine. Further on, principal load cases according to the IEC61400-1 are simulated for a fictitious 5MW VAWT turbine in it’s simplest 2 bladed Darrieus configuration. The IEC61400-1 load cases, originally developed for Horizontal Axis Wind...... Turbines (HAWT’s), are discussed regarding the application to VAWT’s. Further on a small section regarding aerodynamic flow in curved motion is included....

Coherent Lidar Turbulence Measurement for Gust Load Alleviation

Science.gov (United States)

Bogue, Rodney K.; Ehernberger, L. J.; Soreide, David; Bagley, Hal

1996-01-01

Atmospheric turbulence adversely affects operation of commercial and military aircraft and is a design constraint. The airplane structure must be designed to survive the loads imposed by turbulence. Reducing these loads allows the airplane structure to be lighter, a substantial advantage for a commercial airplane. Gust alleviation systems based on accelerometers mounted in the airplane can reduce the maximum gust loads by a small fraction. These systems still represent an economic advantage. The ability to reduce the gust load increases tremendously if the turbulent gust can be measured before the airplane encounters it. A lidar system can make measurements of turbulent gusts ahead of the airplane, and the NASA Airborne Coherent Lidar for Advanced In-Flight Measurements (ACLAIM) program is developing such a lidar. The ACLAIM program is intended to develop a prototype lidar system for use in feasibility testing of gust load alleviation systems and other airborne lidar applications, to define applications of lidar with the potential for improving airplane performance, and to determine the feasibility and benefits of these applications. This paper gives an overview of the ACLAIM program, describes the lidar architecture for a gust alleviation system, and describes the prototype ACLAIM lidar system.

pygrametl: A Powerful Programming Framework for Extract–Transform–Load Programmers

DEFF Research Database (Denmark)

Thomsen, Christian; Pedersen, Torben Bach

    Extract-Transform-Load (ETL) processes are used for extracting data, transforming it and loading it into data warehouses (DWs). Many tools for creating ETL processes exist. The dominating tools all use graphical user interfaces (GUIs) where the developer visually defines the data flow...

Analysis of Mesh Distribution Systems Considering Load Models and Load Growth Impact with Loops on System Performance

Science.gov (United States)

Kumar Sharma, A.; Murty, V. V. S. N.

2014-12-01

The distribution system is the final link between bulk power system and consumer end. A distinctive load flow solution method is used for analysis of the load flow of radial and weakly meshed network based on Kirchhoff's Current Law (KCL) and KVL. This method has excellent convergence characteristics for both radial as well as weakly meshed structure and is based on bus injection to branch current and branch-current to bus-voltage matrix. The main contribution of the paper is: (i) an analysis has been carried out for a weekly mesh network considering number of loops addition and its impact on the losses, kW and kVAr requirements from a system, and voltage profile, (ii) different load models, realistic ZIP load model and load growth impact on losses, voltage profile, kVA and kVAr requirements, (iii) impact of addition of loops on losses, voltage profile, kVA and kVAr requirements from substation, and (iv) comparison of system performance with radial distribution system. Voltage stability is a major concern in planning and operation of power systems. This paper also includes identifying the closeness critical bus which is the most sensitive to the voltage collapse in radial distribution networks. Node having minimum value of voltage stability index is the most sensitive node. Voltage stability index values are computed for meshed network with number of loops added in the system. The results have been obtained for IEEE 33 and 69 bus test system. The results have also been obtained for radial distribution system for comparison.

User`s Guide for the NREL Force and Loads Analysis Program. Version 2.2

Energy Technology Data Exchange (ETDEWEB)

Wright, A D

1992-08-01

The following report gives the reader an overview of and instructions on the proper use of the National Renewable Energy Laboratory Force and Loads Analysis Program (FLAP, version 2.2). It is intended as a tool for prediction of rotor and blade loads and response for two- or three-bladed rigid hub wind turbines. The effects of turbulence are accounted for. The objectives of the report are to give an overview of the code and also show the methods of data input and correct code execution steps in order to model an example two-bladed rigid hub turbine. A large portion of the discussion (Sections 6.0, 7.0, and 8.0) is devoted to the subject of inputting and running the code for wind turbulence effects. The ability to include turbulent wind effects is perhaps the biggest change in the code since the release of FLAP version 2.01 in 1988. This report is intended to be a user`s guide. It does not contain a theoretical discussion on equations of motion, assumptions, underlying theory, etc. It is intended to be used in conjunction with Wright, Buhl, and Thresher (1988).

Advection and dispersion of bed load tracers

Science.gov (United States)

Lajeunesse, Eric; Devauchelle, Olivier; James, François

2018-05-01

We use the erosion-deposition model introduced by Charru et al. (2004) to numerically simulate the evolution of a plume of bed load tracers entrained by a steady flow. In this model, the propagation of the plume results from the stochastic exchange of particles between the bed and the bed load layer. We find a transition between two asymptotic regimes. The tracers, initially at rest, are gradually set into motion by the flow. During this entrainment regime, the plume is strongly skewed in the direction of propagation and continuously accelerates while spreading nonlinearly. With time, the skewness of the plume eventually reaches a maximum value before decreasing. This marks the transition to an advection-diffusion regime in which the plume becomes increasingly symmetrical, spreads linearly, and advances at constant velocity. We analytically derive the expressions of the position, the variance, and the skewness of the plume and investigate their asymptotic regimes. Our model assumes steady state. In the field, however, bed load transport is intermittent. We show that the asymptotic regimes become insensitive to this intermittency when expressed in terms of the distance traveled by the plume. If this finding applies to the field, it might provide an estimate for the average bed load transport rate.

Numerical analysis of flow instability in the water wall of a supercritical CFB boiler with annular furnace

Science.gov (United States)

Xie, Beibei; Yang, Dong; Xie, Haiyan; Nie, Xin; Liu, Wanyu

2016-08-01

In order to expand the study on flow instability of supercritical circulating fluidized bed (CFB) boiler, a new numerical computational model considering the heat storage of the tube wall metal was presented in this paper. The lumped parameter method was proposed for wall temperature calculation and the single channel model was adopted for the analysis of flow instability. Based on the time-domain method, a new numerical computational program suitable for the analysis of flow instability in the water wall of supercritical CFB boiler with annular furnace was established. To verify the code, calculation results were respectively compared with data of commercial software. According to the comparisons, the new code was proved to be reasonable and accurate for practical engineering application in analysis of flow instability. Based on the new program, the flow instability of supercritical CFB boiler with annular furnace was simulated by time-domain method. When 1.2 times heat load disturbance was applied on the loop, results showed that the inlet flow rate, outlet flow rate and wall temperature fluctuated with time eventually remained at constant values, suggesting that the hydrodynamic flow was stable. The results also showed that in the case of considering the heat storage, the flow in the water wall is easier to return to stable state than without considering heat storage.

Cost-optimal power system extension under flow-based market coupling and high shares of photovoltaics

Energy Technology Data Exchange (ETDEWEB)

Hagspiel, Simeon; Jaegemann, Cosima; Lindenberger, Dietmar [Koeln Univ. (Germany). Inst. of Energy Economics; Cherevatskiy, Stanislav; Troester, Eckehard; Brown, Tom [Energynautics GmbH, Langen (Germany)

2012-07-01

Electricity market models, implemented as dynamic programming problems, have been applied widely to identify possible pathways towards a cost-optimal and low carbon electricity system. However, the joint optimization of generation and transmission remains challenging, mainly due to the fact that different characteristics and rules apply to commercial and physical exchanges of electricity in meshed networks. This paper presents a methodology that allows to optimize power generation and transmission infrastructures jointly through an iterative approach based on power transfer distribution factors (PTDFs). As PTDFs are linear representations of the physical load flow equations, they can be implemented in a linear programming environment suitable for large scale problems such as the European power system. The algorithm iteratively updates PTDFs when grid infrastructures are modified due to cost-optimal extension and thus yields an optimal solution with a consistent representation of physical load flows. The method is demonstrated on a simplified three-node model where it is found to be stable and convergent. It is then scaled to the European level in order to find the optimal power system infrastructure development under the prescription of strongly decreasing CO{sub 2} emissions in Europe until 2050 with a specific focus on photovoltaic (PV) power. (orig.)

K-TIF: a two-fluid computer program for downcomer flow dynamics. [PWR

Energy Technology Data Exchange (ETDEWEB)

Amsden, A.A.; Harlow, F.H.

1977-10-01

The K-TIF computer program has been developed for numerical solution of the time-varying dynamics of steam and water in a pressurized water reactor downcomer. The current status of physical and mathematical modeling is presented in detail. The report also contains a complete description of the numerical solution technique, a full description and listing of the computer program, instructions for its use, with a sample printout for a specific test problem. A series of calculations, performed with no change in the modeling parameters, shows consistent agreement with the experimental trends over a wide range of conditions, which gives confidence to the calculations as a basis for investigating the complicated physics of steam-water flows in the downcomer.

PPOOLEX experiments on dynamic loading with pressure feedback

International Nuclear Information System (INIS)

Puustinen, M.; Laine, J.; Raesaenen, A.

2011-01-01

This report summarizes the results of the dynamic loading experiments (DYN series) carried out with the scaled down, two compartment PPOOLEX test facility designed and constructed at LUT. Steam was blown into the dry well compartment and from there through the DN200 vertical blowdown pipe to the condensation pool filled with sub-cooled water. The main purpose of the experiments was to study dynamic loads caused by different condensation modes. Particularly, the effect of counterpressure on loads due to pressure oscillations induced by chugging was of interest. Before the experiments the condensation pool was filled with isothermal water so that the blowdown pipe outlet was submerged by 1.03-1.11 m. The initial temperature of the pool water varied from 11 deg. C to 63 deg. C, the steam flow rate from 290 g/s to 1220 g/s and the temperature of incoming steam from 132 deg. C to 182 deg. C. Non-condensables were pushed from the dry well into the gas space of the wet well with a short discharge of steam before the recorded period of the experiments. As a result of this procedure, the system pressure was at an elevated level in the beginning of the actual experiments. An increased counterpressure was used in the last experiment of the series. The diminishing effect of increased system pressure on chugging intensity and on measured loads is evident from the results of the last experiment. The highest pressure pulses both inside the blowdown pipe and in the condensation pool were about half of those measured with a lower system pressure but otherwise with similar test parameters. The experiments on dynamic loading gave expected results. The loads experienced by pool structures depended strongly on the steam mass flow rate, pool water temperature and system pressure. The DYN experiments indicated that chugging and condensation within the blowdown pipe cause significant dynamic loads in case of strongly sub-cooled pool water. The level of pool water temperature is decisive

PPOOLEX experiments on dynamic loading with pressure feedback

Energy Technology Data Exchange (ETDEWEB)

Puustinen, M.; Laine, J.; Raesaenen, A. (Lappeenranta Univ. of Technology, Nuclear Safety Research Unit (Finland))

2011-01-15

This report summarizes the results of the dynamic loading experiments (DYN series) carried out with the scaled down, two compartment PPOOLEX test facility designed and constructed at LUT. Steam was blown into the dry well compartment and from there through the DN200 vertical blowdown pipe to the condensation pool filled with sub-cooled water. The main purpose of the experiments was to study dynamic loads caused by different condensation modes. Particularly, the effect of counterpressure on loads due to pressure oscillations induced by chugging was of interest. Before the experiments the condensation pool was filled with isothermal water so that the blowdown pipe outlet was submerged by 1.03-1.11 m. The initial temperature of the pool water varied from 11 deg. C to 63 deg. C, the steam flow rate from 290 g/s to 1220 g/s and the temperature of incoming steam from 132 deg. C to 182 deg. C. Non-condensables were pushed from the dry well into the gas space of the wet well with a short discharge of steam before the recorded period of the experiments. As a result of this procedure, the system pressure was at an elevated level in the beginning of the actual experiments. An increased counterpressure was used in the last experiment of the series. The diminishing effect of increased system pressure on chugging intensity and on measured loads is evident from the results of the last experiment. The highest pressure pulses both inside the blowdown pipe and in the condensation pool were about half of those measured with a lower system pressure but otherwise with similar test parameters. The experiments on dynamic loading gave expected results. The loads experienced by pool structures depended strongly on the steam mass flow rate, pool water temperature and system pressure. The DYN experiments indicated that chugging and condensation within the blowdown pipe cause significant dynamic loads in case of strongly sub-cooled pool water. The level of pool water temperature is decisive

Phosphorus and suspended sediment load estimates for the Lower Boise River, Idaho, 1994-2002

Science.gov (United States)

Donato, Mary M.; MacCoy, Dorene E.

2004-01-01

The U.S. Geological Survey used LOADEST, newly developed load estimation software, to develop regression equations and estimate loads of total phosphorus (TP), dissolved orthophosphorus (OP), and suspended sediment (SS) from January 1994 through September 2002 at four sites on the lower Boise River: Boise River below Diversion Dam near Boise, Boise River at Glenwood Bridge at Boise, Boise River near Middleton, and Boise River near Parma. The objective was to help the Idaho Department of Environmental Quality develop and implement total maximum daily loads (TMDLs) by providing spatial and temporal resolution for phosphorus and sediment loads and enabling load estimates made by mass balance calculations to be refined and validated. Regression models for TP and OP generally were well fit on the basis of regression coefficients of determination (R2), but results varied in quality from site to site. The TP and OP results for Glenwood probably were affected by the upstream wastewater-treatment plant outlet, which provides a variable phosphorus input that is unrelated to river discharge. Regression models for SS generally were statistically well fit. Regression models for Middleton for all constituents, although statistically acceptable, were of limited usefulness because sparse and intermittent discharge data at that site caused many gaps in the resulting estimates. Although the models successfully simulated measured loads under predominant flow conditions, errors in TP and SS estimates at Middleton and in TP estimates at Parma were larger during high- and low-flow conditions. This shortcoming might be improved if additional concentration data for a wider range of flow conditions were available for calibrating the model. The average estimated daily TP load ranged from less than 250 pounds per day (lb/d) at Diversion to nearly 2,200 lb/d at Parma. Estimated TP loads at all four sites displayed cyclical variations coinciding with seasonal fluctuations in discharge

Seasonal Variations and Yearly Trend Evaluations of Sedimentation Loads: A Case Study at Chalok River, Terengganu, Malaysia

Directory of Open Access Journals (Sweden)

Aida Soraya Shamsuddin

2014-01-01

Full Text Available The aims of this study were to determine the relationship between seasonal variations (wet and dry periods on sedimentation loads and to identify the yearly trend of sedimentation loads at Chalok River, Terengganu, Malaysia from 2003 to 2008. It was found that wet and dry periods influenced the transportation of suspended sediment into the river significantly. The highest suspended sediment loads at Chalok River occurred during the wet period when the intensity of rainfall is high. Besides, the rainfall, water level, stream flow and suspended sediment loads also were analysed using Spearman correlation to identify their relationships. The results showed significant positive relationship between suspended sediment loads with rainfall (r = 0.664, p< 0.05, water level (r = 0.923, p< 0.05 and stream flow (r = 0.919, p< 0.05. Multiple linear regressions revealed 63% of high suspended sediment loads at Chalok River can be explained by rainfall, water level and stream flow. The trends of rainfall, water level, stream flow and suspended sediment loads were analysed by using Mann-Kendall trend test where the results showed that there is a significant increasing trend for suspended sediment loads but no significant increase trend for rainfall, water level and stream flow over the studied periods. It is evident that the evaluations conducted in this study are useful in providing better understanding and reliable conclusion on the basis of seasonal variations and other environmental variables that affect the sedimentations loads in the river. Such effort provides holistic information for effective and wise management policy of river basin management in the future.

MVA power flow and loss analysis for electricity market

International Nuclear Information System (INIS)

Wu, Z.Q.; Chen, G.Z.

2001-01-01

MVA power-flow and loss analysis is the basis for allocating the fixed costs and power losses under electricity-market deregulation. It is pointed out that the decomposition allocation of active and reactive power losses is not reasonable. The theory of active and reactive loss allocation and branch-power-flow decomposition has been proposed. Various contributory factors have been deduced. These contributory factors include the contribution factors of the active and reactive generation power, load-power-to-branch flows, the contribution factors of active and reactive generation power to active and reactive load power, the contribution factors of active and reactive load power to generation power, and the contribution factors of active and reactive load power and active and reactive generation power to line power losses. The detailed calculation results are presented and analysed, demonstrating that the theory presented provides a good charging algorithm for all the market participants. (Author)

PIV-based load determination in aircraft propellers

OpenAIRE

Ragni, D.

2012-01-01

The thesis describes the application of particle image velocimetry (PIV) to study the aerodynamic loads of airfoils and aircraft propellers. The experimental work focuses on the development of a measurement procedure to infer the pressure of the flow field from the velocity distribution obtained by PIV velocimetry. The technique offers important advantages in aircraft propellers, since the loads can be locally inspected without the need to install pressure sensors and momentum balances in rot...

Heat load of a GaAs photocathode in an SRF electron gun

International Nuclear Information System (INIS)

Wang Erdong; Zhao Kui; Jorg Kewisch; Ilan Ben-Zvi; Andrew Burrill; Trivini Rao; Wu Qiong; Animesh Jain; Ramesh Gupta; Doug Holmes

2011-01-01

A great deal of effort has been made over the last decades to develop a better polarized electron source for high energy physics. Several laboratories operate DC guns with a gallium arsenide photocathode, which yield a highly polarized electron beam. However, the beam's emittance might well be improved by using a superconducting radio frequency (SRF) electron gun, which delivers beams of a higher brightness than that from DC guns because the field gradient at the cathode is higher. SRF guns with metal and CsTe cathodes have been tested successfully. To produce polarized electrons, a Gallium-Arsenide photo-cathode must be used: an experiment to do so in a superconducting RF gun is under way at BNL. Since a bulk gallium arsenide (GaAs) photocathode is normal conducting, a problem arises from the heat load stemming from the cathode. We present our measurements of the electrical resistance of GaAs at cryogenic temperatures, a prediction of the heat load and verification by measuring the quality factor of the gun with and without the cathode at 2 K. We simulate heat generation and flow from the GaAs cathode using the ANSYS program. By following the findings with the heat load model, we designed and fabricated a new cathode holder (plug) to decrease the heat load from GaAs. (authors)

Phase change based cooling for high burst mode heat loads with temperature regulation above the phase change temperature

Science.gov (United States)

The United States of America as represented by the United States Department of Energy

2009-12-15

An apparatus and method for transferring thermal energy from a heat load is disclosed. In particular, use of a phase change material and specific flow designs enables cooling with temperature regulation well above the fusion temperature of the phase change material for medium and high heat loads from devices operated intermittently (in burst mode). Exemplary heat loads include burst mode lasers and laser diodes, flight avionics, and high power space instruments. Thermal energy is transferred from the heat load to liquid phase change material from a phase change material reservoir. The liquid phase change material is split into two flows. Thermal energy is transferred from the first flow via a phase change material heat sink. The second flow bypasses the phase change material heat sink and joins with liquid phase change material exiting from the phase change material heat sink. The combined liquid phase change material is returned to the liquid phase change material reservoir. The ratio of bypass flow to flow into the phase change material heat sink can be varied to adjust the temperature of the liquid phase change material returned to the liquid phase change material reservoir. Varying the flowrate and temperature of the liquid phase change material presented to the heat load determines the magnitude of thermal energy transferred from the heat load.

Estimation of the Diesel Particulate Filter Soot Load Based on an Equivalent Circuit Model

Directory of Open Access Journals (Sweden)

Yanting Du

2018-02-01

Full Text Available In order to estimate the diesel particulate filter (DPF soot load and improve the accuracy of regeneration timing, a novel method based on an equivalent circuit model is proposed based on the electric-fluid analogy. This proposed method can reduce the impact of the engine transient operation on the soot load, accurately calculate the flow resistance, and improve the estimation accuracy of the soot load. Firstly, the least square method is used to identify the flow resistance based on the World Harmonized Transient Cycle (WHTC test data, and the relationship between flow resistance, exhaust temperature and soot load is established. Secondly, the online estimation of the soot load is achieved by using the dual extended Kalman filter (DEKF. The results show that this method has good convergence and robustness with the maximal absolute error of 0.2 g/L at regeneration timing, which can meet engineering requirements. Additionally, this method can estimate the soot load under engine transient operating conditions and avoids a large number of experimental tests, extensive calibration and the analysis of complex chemical reactions required in traditional methods.

Preliminary analysis of effects of thermal loading on gas and heat flow within the framework of the LBNL/USGS site-scale model

International Nuclear Information System (INIS)

Wu, Y.S.; Chen, G.; Bodvarsson, G.

1995-12-01

The US Department of Energy is performing detailed site characterization studies at Yucca Mountain to determine its suitability as a geological repository site for high level nuclear wastes. As part of these research efforts, a three-dimensional, site-scale unsaturated-zone model has been developed at Lawrence Berkeley National Laboratory (LBNL) in collaboration with the US Geological Survey (USGS). The primary objectives of developing the 3-D site-scale model are to predict the ambient hydrogeological conditions and the movement of moisture and gas within the unsaturated zone of the mountain. In addition, the model has the capability of modeling non-isothermal flow and transport phenomena at the mountain. Applications of such a site-scale model should include evaluation of effects of thermal loading on heated gas and heat flow through the mountain for long-term performance assessment of the repository. Emplacement of heat-generating, high-level nuclear wastes at Yucca Mountain would create complex multiphase fluid flow and heat transfer processes. The physical mechanisms include conductive and convective heat transfer, phase change phenomena (vaporization and condensation), flow of liquid and gas phases under variably-saturated condition, diffusion and dispersion of vapor and gas, vapor sorption, and vapor-pressure lowering effects. The heterogeneity of complicated geological setting at Yucca Mountain, such as alternating, layers of porous-fractured rocks, will significantly affect the processes of fluid and heat flow

Lessons Learned: A review of utility experience with conservation and load management programs for commercial and industrial customers

Energy Technology Data Exchange (ETDEWEB)

Nadel, S.

1990-10-01

This report examines utility experience with conservation and load management (C LM) programs of commercial and industrial (C I) customers in order to summarize the lessons learned from program experiences to date and what these teach us about how to operate successful programs in the future. This analysis was motivated by a desire to learn about programs which achieve high participation rates and high electricity savings while remaining cost effective. Also, we wanted to review the very latest experiences with innovative program approaches -- approaches that might prove useful to utilities as they scale up their C LM activities. Specific objectives of this phase of the study are threefold: (1) To disseminate information on utility C LM experience to a nationwide audience. (2) To review current New York State utility programs and make suggestions on how these programs can be improved. (3) To collect data for the final phase of the American Council for an Energy-Efficient Economy/New York State Energy Research and Development Authority project, which will examine the savings that are achievable if C LM programs are pushed to the limit'' of current knowledge on how to structure and run cost-effective C LM programs. 19 tabs.

Magnetogasdynamic Flow Acceleration in a Scramjet Nozzle

National Research Council Canada - National Science Library

Harrington, Brian

2004-01-01

.... The parameters of conductivity pattern and load factor are varied in both inviscid and viscous flow regimes with the intent of increasing axial force exerted on the flow through a scramjet accelerator...

Research on the fundamental process of thermal-hydraulic behaviors in severe accident. Behavior of fine droplet flow. JAERI's nuclear research promotion program, H10-027-7. Contract research

International Nuclear Information System (INIS)

Kataoka, Isao; Yoshida, Kenji; Matsuura, Keizo

2002-03-01

Analytical and experimental researches were carried out on the behavior of fine droplet flow in relation to the fundamental phenomena of thermohydraulics in severe accident. Simulation program of fine droplet behavior in turbulent gas flow was developed based on the eddy interaction model with improvement of Graham's stochastic model on eddy lifetime and eddy size. Furthermore, the developed program are capable of simulating the droplet behavior in annular dispersed flow based on the models of droplet entrainment from liquid film and turbulence modification of gas phase by liquid film. This program was confirmed by the various experimental data on droplet diffusion, deposition. Furthermore, this program was applied to the three dimensional droplet flow with the satisfactory agreement of experimental data. This means the developed program can be used as a simulation program for analysis of severe accident. Experimental research was carried out on the effect of liquid film on the turbulence field of gas flow in annular and annular dispersed flow. Averaged and turbulent velocity of gas phase were measured under various gas and liquid film flow rates. Turbulent velocity of gas phase in annular flow increased compared with single phase gas flow. This is due to turbulence generation by waves in liquid film. Corresponding to the turbulence modification by liquid film, distribution of averaged velocity of gas phase became flattened compared with single phase gas flow. (author)

LLUVIA-II: A program for two-dimensional, transient flow through partially saturated porous media

International Nuclear Information System (INIS)

Eaton, R.R.; Hopkins, P.L.

1992-08-01

LLUVIA-II is a program designed for the efficient solution of two- dimensional transient flow of liquid water through partially saturated, porous media. The code solves Richards equation using the method-of-lines procedure. This document describes the solution procedure employed, input data structure, output, and code verification

Lower bounds of collapse loads in axisymmetrical vessels

International Nuclear Information System (INIS)

Fonseca Neto, J. de D.; Ebecken, N.F.F.

1981-01-01

The rigid-plastic limit analysis of shells of revolution subject to rotationally symmetric loadings, is presented. After assembling the finite elements, the limit analysis program is reduced to a simple application of the non-linear programming technique, where the sequential unconstrained minimization technique (SUMT) is utilized for the statically admissible approach. Lower bounds of the collapse loads are presented and compared with the results described in the literature. (Author) [pt

Tailoring of electron flow current in magnetically insulated transmission lines

Directory of Open Access Journals (Sweden)

J. P. Martin

2009-03-01

Full Text Available It is desirable to optimize (minimizing both the inductance and electron flow the magnetically insulated vacuum sections of low impedance pulsed-power drivers. The goal of low inductance is understandable from basic efficiency arguments. The goal of low electron flow results from two observations: (1 flowing electrons generally do not deliver energy to (or even reach most loads, and thus constitute a loss mechanism; (2 energetic electrons deposited in a small area can cause anode damage and anode plasma formation. Low inductance and low electron flow are competing goals; an optimized system requires a balance of the two. While magnetically insulated systems are generally forgiving, there are times when optimization is crucial. For example, in large pulsed-power drivers used to energize high energy density physics loads, the electron flow as a fraction of total current is small, but that flow often reaches the anode in relatively small regions. If the anode temperature becomes high enough to desorb gas, the resulting plasma initiates a gap closure process that can impact system performance. Magnetic-pressure driven (z pinches and material equation of state loads behave like a fixed inductor for much of the drive pulse. It is clear that neither fixed gap nor constant-impedance transmission lines are optimal for driving inductive loads. This work shows a technique for developing the optimal impedance profile for the magnetically insulated section of a high-current driver. Particle-in-cell calculations are used to validate the impedance profiles developed in a radial disk magnetically insulated transmission line geometry. The input parameters are the spacing and location of the minimum gap, the effective load inductance, and the desired electron flow profile. The radial electron flow profiles from these simulations are in good agreement with theoretical predictions when driven at relatively high voltage (i.e., V≥2  MV.

Comparison of particle swarm optimization and dynamic programming for large scale hydro unit load dispatch

International Nuclear Information System (INIS)

Cheng Chuntian; Liao Shengli; Tang Zitian; Zhao Mingyan

2009-01-01

Dynamic programming (DP) is one of classic and sophisticated optimization methods that have successfully been applied to solve the problem of hydro unit load dispatch (HULD). However, DP will be faced with the curse of dimensionality with the increase of unit number and installed generating capacity of hydropower station. With the appearance of the huge hydropower station similar to the Three George with 26 generators of 700 MW, it is hard to apply the DP to large scale HULD problem. It is crucial to seek for other optimization techniques in order to improve the operation quality and efficiency. Different with the most of literature about power generation scheduling that focused on the comparisons of novel PSO algorithms with other techniques, the paper will pay emphasis on comparison study of PSO with DP based on a case hydropower station. The objective of study is to seek for an effective and feasible method for the large scale of hydropower station of the current and future in China. This paper first compares the performance of PSO and DP using a sample load curve of the Wujiangdu hydropower plant located in the upper stream of the Yangtze River in China and contained five units with the installed capacity of 1250 MW. Next, the effect of different load interval and unit number on the optimal results and efficiency of two methods has also been implemented. The comparison results show that the PSO is feasible for HULD. Furthermore, we simulated the effect of the magnitude of unit number and load capacity on the optimal results and cost time. The simulation comparisons show that PSO has a great advantage over DP in the efficiency and will be one of effective methods for HULD problem of huge hydropower stations.

Comparison of particle swarm optimization and dynamic programming for large scale hydro unit load dispatch

Energy Technology Data Exchange (ETDEWEB)

Cheng Chuntian, E-mail: ctcheng@dlut.edu.c [Department of Civil and Hydraulic Engineering, Dalian University of Technology, 116024 Dalian (China); Liao Shengli; Tang Zitian [Department of Civil and Hydraulic Engineering, Dalian University of Technology, 116024 Dalian (China); Zhao Mingyan [Department of Environmental Science and Engineering, Tsinghua University, 100084 Beijing (China)

2009-12-15

Dynamic programming (DP) is one of classic and sophisticated optimization methods that have successfully been applied to solve the problem of hydro unit load dispatch (HULD). However, DP will be faced with the curse of dimensionality with the increase of unit number and installed generating capacity of hydropower station. With the appearance of the huge hydropower station similar to the Three George with 26 generators of 700 MW, it is hard to apply the DP to large scale HULD problem. It is crucial to seek for other optimization techniques in order to improve the operation quality and efficiency. Different with the most of literature about power generation scheduling that focused on the comparisons of novel PSO algorithms with other techniques, the paper will pay emphasis on comparison study of PSO with DP based on a case hydropower station. The objective of study is to seek for an effective and feasible method for the large scale of hydropower station of the current and future in China. This paper first compares the performance of PSO and DP using a sample load curve of the Wujiangdu hydropower plant located in the upper stream of the Yangtze River in China and contained five units with the installed capacity of 1250 MW. Next, the effect of different load interval and unit number on the optimal results and efficiency of two methods has also been implemented. The comparison results show that the PSO is feasible for HULD. Furthermore, we simulated the effect of the magnitude of unit number and load capacity on the optimal results and cost time. The simulation comparisons show that PSO has a great advantage over DP in the efficiency and will be one of effective methods for HULD problem of huge hydropower stations.

Comparison of particle swarm optimization and dynamic programming for large scale hydro unit load dispatch

Energy Technology Data Exchange (ETDEWEB)

Chun-tian Cheng; Sheng-li Liao; Zi-Tian Tang [Dept. of Civil and Hydraulic Engineering, Dalian Univ. of Technology, 116024 Dalian (China); Ming-yan Zhao [Dept. of Environmental Science and Engineering, Tsinghua Univ., 100084 Beijing (China)

2009-12-15

Dynamic programming (DP) is one of classic and sophisticated optimization methods that have successfully been applied to solve the problem of hydro unit load dispatch (HULD). However, DP will be faced with the curse of dimensionality with the increase of unit number and installed generating capacity of hydropower station. With the appearance of the huge hydropower station similar to the Three George with 26 generators of 700 MW, it is hard to apply the DP to large scale HULD problem. It is crucial to seek for other optimization techniques in order to improve the operation quality and efficiency. Different with the most of literature about power generation scheduling that focused on the comparisons of novel PSO algorithms with other techniques, the paper will pay emphasis on comparison study of PSO with DP based on a case hydropower station. The objective of study is to seek for an effective and feasible method for the large scale of hydropower station of the current and future in China. This paper first compares the performance of PSO and DP using a sample load curve of the Wujiangdu hydropower plant located in the upper stream of the Yangtze River in China and contained five units with the installed capacity of 1250 MW. Next, the effect of different load interval and unit number on the optimal results and efficiency of two methods has also been implemented. The comparison results show that the PSO is feasible for HULD. Furthermore, we simulated the effect of the magnitude of unit number and load capacity on the optimal results and cost time. The simulation comparisons show that PSO has a great advantage over DP in the efficiency and will be one of effective methods for HULD problem of huge hydropower stations. (author)

Processes Affecting Agricultural Drainwater Quality and Organic Carbon Loads in California's Sacramento–San Joaquin Delta

Directory of Open Access Journals (Sweden)

Steven J. Deverel

2007-05-01

Full Text Available From 2000 to 2003 we quantified drain flow, drain-and ground-water chemistry and hydrogeologic conditions on Twitchell Island in the Sacramento-San Joaquin Delta. The primary objective was to quantify processes affecting organic carbon concentrations and loads in agricultural drainage water. We collected physical and chemical data in southern and northern areas: TN and TS, respectively. Corn grew in both areas during the spring and summer. The peat soils in the TN area are more decomposed than those in the TS area. Results elucidate processes affecting drain flow and concentrations under varying hydrologic conditions. During May through November, groundwater flows from the permanently saturated zone to drainage ditches, and the resulting average drainage-water quality and dissolved organic carbon (DOC concentration was similar to the groundwater; the median DOC loads in the TN and TS study areas ranged from 9 to 27 g C/ha-day. The major ion chemistry and stable isotope data confirmed that groundwater was the primary source of drainflow. In contrast, during December through April the drainwater is supplied from the shallow, variably saturated soil-zone. The DOC concentrations, major-ion chemistry, and stable isotope data indicate that the shallow-zone water is partially evaporated and oxidized. Higher flows and DOC concentrations during these months result in higher median DOC loads, which ranged from 84 to 280 g C/ha-day. During December through April, increasing groundwater levels in the shallow peat layers and mobilization of organic carbon result in high drain flow and increased trihalomethane precursor concentrations and loads. On a per mass DOC basis, drain water collected during high flow periods is less likely to form THMs than during low flow periods. However, the high flows and subsequent high concentrations contribute to substantially higher trihalomethane precursor and DOC loads.

Appropriate heat load ratio of generator for different types of air cooled lithium bromide–water double effect absorption chiller

International Nuclear Information System (INIS)

Li, Zeyu; Liu, Jinping

2015-01-01

Highlights: • Effect of heat load ratio of generator on the performance was analyzed. • The performance is sensitive to heat load ratio of generator. • The appropriate heat load ratio of generator for four systems was obtained. • The change of appropriate heat load ratio of generator for four systems was studied. - Abstract: The lower coefficient of performance and higher risk of crystallization in the higher surrounding temperature is the primary disadvantage of air cooled lithium bromide–water double effect absorption chiller. Since the coefficient of performance and risk of crystallization strongly depend on the heat load ratio of generator, the appropriate heat load ratio of generator can improve the performance as the surrounding temperature is higher. The paper mainly deals with the appropriate heat load ratio of generator of air cooled lithium bromide–water double effect absorption chiller. Four type systems named series, pre-parallel, rear parallel and reverse parallel flow configuration were considered. The corresponding parametric model was developed to analyze the comprehensive effect of heat load ratio of generator on the coefficient of performance and risk of crystallization. It was found that the coefficient of performance goes up linearly with the decrease of heat load ratio of generator. Simultaneously, the risk of crystallization also rises slowly at first but increases fast finally. Consequently, the appropriate heat load ratio of generator for the series and pre-parallel flow type systems is suggested to be 0.02 greater than the minimum heat load ratio of generator and that for the rear parallel and reverse parallel flow chillers should be 0.01 higher than the minimum heat load ratio of generator. Besides, the changes of minimum heat load ratio of generator for different type systems with the working condition were analyzed and compared. It was found that the minimum heat load ratio of generator goes up with the increase of

K-FIX: a computer program for transient, two-dimensional, two-fluid flow

International Nuclear Information System (INIS)

Rivard, W.C.; Torrey, M.D.

1976-11-01

The transient dynamics of two-dimensional, two-phase flow with interfacial exchange are calculated at all flow speeds using the K-FIX program. Each phase is described in terms of its own density, velocity, and temperature. The six field equations for the two phases couple through mass, momentum, and energy exchange. The equations are solved using an Eulerian finite difference technique that implicitly couples the rates of phase transitions, momentum, and energy exchange to determination of the pressure, density, and velocity fields. The implicit solution is accomplished iteratively without linearizing the equations, thus eliminating the need for numerous derivative terms. K-FIX is written in a highly modular form to be easily adaptable to a variety of problems. It is applied to growth of an isolated steam bubble in a superheated water pool

Parameter estimation of an ARMA model for river flow forecasting using goal programming

Science.gov (United States)

Mohammadi, Kourosh; Eslami, H. R.; Kahawita, Rene

2006-11-01

SummaryRiver flow forecasting constitutes one of the most important applications in hydrology. Several methods have been developed for this purpose and one of the most famous techniques is the Auto regressive moving average (ARMA) model. In the research reported here, the goal was to minimize the error for a specific season of the year as well as for the complete series. Goal programming (GP) was used to estimate the ARMA model parameters. Shaloo Bridge station on the Karun River with 68 years of observed stream flow data was selected to evaluate the performance of the proposed method. The results when compared with the usual method of maximum likelihood estimation were favorable with respect to the new proposed algorithm.

Implementation of a Small Type DC Microgrid Based on Fuzzy Control and Dynamic Programming

Directory of Open Access Journals (Sweden)

Chin-Hsing Cheng

2016-09-01

Full Text Available A DC microgrid (DC-MG is a novel power system that uses DC distribution in order to provide high quality power. The study system is made by a photovoltaic array (PV, a wind generator (WG, a fuel cell (FC, and an energy storage system (ESS to establish a small type DC microgrid, with the bus being established by DC/DC converters with fuzzy controllers. An overall power dispatch was designed for the proposed system to distribute the power flows among the different energy sources and the storage unit in the system in order to satisfy the load requirements throughout an entire 24-h period. The structure of a power supervisor based on an optimal power dispatch algorithm is here proposed. Optimization was performed using dynamic programming (DP. In this paper, a system configuration of a DC microgrid is analyzed in different scenarios to show the efficacy of the control for all devices for the variable weather conditions with different DC loads. Thus, the voltage level and the power flow of the system are shown for different load conditions.

Wind Structure and Wind Loading

DEFF Research Database (Denmark)

Brorsen, Michael

The purpose of this note is to provide a short description of wind, i.e. of the flow in the atmosphere of the Earth and the loading caused by wind on structures. The description comprises: causes to the generation of windhe interaction between wind and the surface of the Earthhe stochastic nature...

Calculation of quantities of interest in high energy physics using visual basic 3.0. The Flow Tensor Program

International Nuclear Information System (INIS)

Besliu, C.; Jipa, A.; Zaharia, R.

1995-01-01

The Flow Tensor is an important physical quantity in High Energy Physics. The program used for the calculation of the Flow Tensor has been a complex menu-driven application, to allow the selection of various triggers for the studied reaction, of the number of traces in each studied event, of the momentum cut values for the resulting particles of fragments in each event, etc. We realised all that requests using a very modern and powerful tool: Visual Basic 3.0. This programming system allows the realisation of Windows-like programs and has numerous facilities: OLE (Object Linking and Embedding), the possibility to create professional graphics, to work with databases, to create and compile Windows-like help files. All these advantages make the effort to learn Visual Basic 3.0 worthwhile. (author)

Analysis and characterization of security regions in power systems. Part I. Load flow feasibility conditions in power networks

Energy Technology Data Exchange (ETDEWEB)

Jarjis, J; Galiana, F D

1980-03-01

A set theoretic analysis of loadflow feasibility of a general power network with arbitrary PQ, PV and slack buses is presented. Load-flow feasibility is that property of a power network defining the theoretical limitations on the bus injections under which a steady state equilibrium exists. The set theoretic analysis is based on the study of the conical loadflow feasibility region. This region is characterised by a set of supporting hyperplanes each of which defines an explicit necessary condition for loadflow feasibility on the bus injections. A quantitative measure of loadflow feasibility for an arbitrary given operating injection vector is defined through a computable scalar stability margin. This stability margin permits the loadflow feasibility of different injections and network structures to be quantitatively compared and analysed.

Fifth Baltic Sea pollution load compilation (PLC-5)

Energy Technology Data Exchange (ETDEWEB)

Knuuttila, S.; Svendsen, L. M.; Staaf, H.; Kotilainen, P.; Boutrup, S.; Pyhala, M.; Durkin, M.

2011-07-01

This report includes the main results from the Fifth Pollution Load Compilation abbreviated PLC-5. It includes quantified annual waterborne total loads (from rivers, unmonitored and coastal areas as well as direct point and diffuse sources discharging directly to the Baltic Sea) from 1994 to 2008 to provide a basis for evaluating any decreasing (or increasing) trends in the total waterborne inputs to the Baltic Sea. Chapter 1 contains the objectives of PLC and the framework on classification of inputs and sources. Chapter 2 includes a short description of the Baltic Sea catchment area, while the methods for quantification and analysis together with quality assurance topics are briefly introduced in Chapter 3. More detailed information on methodologies is presented in the PLC-5 guidelines (HELCOM 2006). Chapter 4 reports the total inputs to the Baltic Sea of nutrients and selected heavy metals. Furthermore, the results of the quatification of discharges and losses of nitrogen and phosphorus from point and diffuse sources into inland surface waters within the Baltic Sea catchment area (source-oriented approach or gross loads) as well as the total load to the maritime area (load-oriented approarch or net loads) in 2006 are shown. Typically, results are presented by country and by main Baltic Sea sub-region. In Chapter 5, flow normalization is introduced and the results of trend analyses on 1994-2008 time series data on total waterborne loads of nitrogen and phosphorus are given together with a first evaluation of progress in obtaining the provisional reduction targets by country and by main Baltic Sea sub-region. Chapter 6 includes discussion of some of the main conclusions and advice for future PLCs. The annexes contain the flow-normalized annual load data and figures and tables with results from the PLC-5.

Piping hydrodynamic loads for a PWR power up-rate with steam generator replacement

International Nuclear Information System (INIS)

Julie M Jarvis; Allen T Vieira; James M Gilmer

2005-01-01

Full text of publication follows: Pipe break hydrodynamic loads are calculated for various systems in a PWR for a Power Up-rate (PUR) with a Steam Generator Replacement (SGR). PUR with SGR can change the system pressures, mass flowrates and pipe routing/configuration. These changes can alter the steam generator piping steam/water hammer loads. This paper discusses the need to benchmark against the original design basis, the use of different modeling techniques, and lessons learned. Benchmarking for licensing in the United States is vital in consideration of 10CFR50.59 and other licensing and safety issues. RELAP5 and its force post-processor R5FORCE are used to model the transient loads for various piping systems such as main feedwater and blowdown systems. Other modeling applications, including the Bechtel GAFT program, are used to evaluate loadings in the main steam piping. Forces are calculated for main steam turbine stop valve closure, feedwater pipe breaks and subsequent check valve slam, and blowdown isolation valve closure. These PUR/SGR forces are compared with the original design basis forces. Modeling techniques discussed include proper valve closure modeling, sonic velocity changes due to pipe material changes, and two phase flow effects. Lessons learned based on analyses done for several PWR PUR with SGR are presented. Lessons learned from these analyses include choosing the optimal replacement piping size and routing to improve system performance without resulting in excessive piping loads. (authors)

Design and performance of a 2-megawatt high voltage dc test load

International Nuclear Information System (INIS)

Horan, D.; Kustom, R.; Ferguson, M.

1994-01-01

A high-power water-cooled resistive load which simulates the electrical load characteristics of a high-power klystron, capable of a 2 MW dissipation at 95 kV DC, is designed and installed. The load utilizes wirewound resistor elements suspended inside G-11 insulated tubing contained within a single-wall 316 stainless steel pressure vessel with flanged elliptical heads. The vessel supplies a continuous flow of deionized water. Baffles fabricated from G-10 sheets support the tubing and promote water turbulence to maximize heat removal. A companion oil tank houses resistive filament and mod-anode power supply test loads, plus an electrical interlock system which provides protection from inadequate water flow, excessive oil temperature, and arcing in either the pressure vessel or oil tank. A secondary safety system consists of both hydrostatic and steam pressure relief valves on the pressure vessel. Power supply tests indicate the load simulates the electrical load characteristics of a high-power klystron to a degree sufficient to accurately performance-test the rf high voltage power supplies used at the Advanced Photon Source

Use of Gene Expression Programming in regionalization of flow duration curve

Science.gov (United States)

Hashmi, Muhammad Z.; Shamseldin, Asaad Y.

2014-06-01

In this paper, a recently introduced artificial intelligence technique known as Gene Expression Programming (GEP) has been employed to perform symbolic regression for developing a parametric scheme of flow duration curve (FDC) regionalization, to relate selected FDC characteristics to catchment characteristics. Stream flow records of selected catchments located in the Auckland Region of New Zealand were used. FDCs of the selected catchments were normalised by dividing the ordinates by their median value. Input for the symbolic regression analysis using GEP was (a) selected characteristics of normalised FDCs; and (b) 26 catchment characteristics related to climate, morphology, soil properties and land cover properties obtained using the observed data and GIS analysis. Our study showed that application of this artificial intelligence technique expedites the selection of a set of the most relevant independent variables out of a large set, because these are automatically selected through the GEP process. Values of the FDC characteristics obtained from the developed relationships have high correlations with the observed values.

Reducibility of ceria-lanthana mixed oxides under temperature programmed hydrogen and inert gas flow conditions

International Nuclear Information System (INIS)

Bernal, S.; Blanco, G.; Cifredo, G.; Perez-Omil, J.A.; Pintado, J.M.; Rodriguez-Izquierdo, J.M.

1997-01-01

The present paper deals with the preparation and characterization of La/Ce mixed oxides, with La molar contents of 20, 36 and 57%. We carry out the study of the structural, textural and redox properties of the mixed oxides, comparing our results with those for pure ceria. For this aim we use temperature programmed reduction (TPR), temperature programmed desorption (TPD), nitrogen physisorption at 77 K, X-ray diffraction and high resolution electron microscopy. The mixed oxides are more easy to reduce in a flow of hydrogen than ceria. Moreover, in an inert gas flow they release oxygen in higher amounts and at lower temperatures than pure CeO 2 . The textural stability of the mixed oxides is also improved by incorporation of lanthana. All these properties make the ceria-lanthana mixed oxides interesting alternative candidates to substitute ceria in three-way catalyst formulations. (orig.)

Toward Understanding Tip Leakage Flows in Small Compressor Cores Including Stator Leakage Flow

Science.gov (United States)

Berdanier, Reid A.; Key, Nicole L.

2017-01-01

The focus of this work was to provide additional data to supplement the work reported in NASA/CR-2015-218868 (Berdanier and Key, 2015b). The aim of that project was to characterize the fundamental flow physics and the overall performance effects due to increased rotor tip clearance heights in axial compressors. Data have been collected in the three-stage axial research compressor at Purdue University with a specific focus on analyzing the multistage effects resulting from the tip leakage flow. Three separate rotor tip clearances were studied with nominal tip clearance gaps of 1.5 percent, 3.0 percent, and 4.0 percent based on a constant annulus height. Overall compressor performance was previously investigated at four corrected speedlines (100 percent, 90 percent, 80 percent, and 68 percent) for each of the three tip clearance configurations. This study extends the previously published results to include detailed steady and time-resolved pressure data at two loading conditions, nominal loading (NL) and high loading (HL), on the 100 percent corrected speedline for the intermediate clearance level (3.0 percent). Steady detailed radial traverses of total pressure at the exit of each stator row are supported by flow visualization techniques to identify regions of flow recirculation and separation. Furthermore, detailed radial traverses of time-resolved total pressures at the exit of each rotor row have been measured with a fast-response pressure probe. These data were combined with existing three-component velocity measurements to identify a novel technique for calculating blockage in a multistage compressor. Time-resolved static pressure measurements have been collected over the rotor tips for all rotors with each of the three tip clearance configurations for up to five loading conditions along the 100 percent corrected speedline using fast-response piezoresistive pressure sensors. These time-resolved static pressure measurements reveal new knowledge about the

Transient Three-Dimensional Analysis of Side Load in Liquid Rocket Engine Nozzles

Science.gov (United States)

Wang, Ten-See

2004-01-01

Three-dimensional numerical investigations on the nozzle start-up side load physics were performed. The objective of this study is to identify the three-dimensional side load physics and to compute the associated aerodynamic side load using an anchored computational methodology. The computational methodology is based on an unstructured-grid, and pressure-based computational fluid dynamics formulation, and a simulated inlet condition based on a system calculation. Finite-rate chemistry was used throughout the study so that combustion effect is always included, and the effect of wall cooling on side load physics is studied. The side load physics captured include the afterburning wave, transition from free- shock to restricted-shock separation, and lip Lambda shock oscillation. With the adiabatic nozzle, free-shock separation reappears after the transition from free-shock separation to restricted-shock separation, and the subsequent flow pattern of the simultaneous free-shock and restricted-shock separations creates a very asymmetric Mach disk flow. With the cooled nozzle, the more symmetric restricted-shock separation persisted throughout the start-up transient after the transition, leading to an overall lower side load than that of the adiabatic nozzle. The tepee structures corresponding to the maximum side load were addressed.

Loads and loads and loads: The influence of prospective load, retrospective load, and ongoing task load in prospective memory

Directory of Open Access Journals (Sweden)

Beat eMeier

2015-06-01

Full Text Available In prospective memory tasks different kinds of load can occur. Adding a prospective memory task can impose a load on ongoing task performance. Adding ongoing task load can affect prospective memory performance. The existence of multiple target events increases prospective load and adding complexity to the to-be-remembered action increases retrospective load. In two experiments, we systematically examined the effects of these different types of load on prospective memory performance. Results showed an effect of prospective load on costs in the ongoing task for categorical targets (Experiment 2, but not for specific targets (Experiment 1. Retrospective load and ongoing task load both affected remembering the retrospective component of the prospective memory task. We suggest that prospective load can enhance costs in the ongoing task due to additional monitoring requirements. Retrospective load and ongoing task load seem to impact the division of resources between the ongoing task and retrieval of the retrospective component, which may affect disengagement from the ongoing task. In general, the results demonstrate that the different types of load affect prospective memory differentially.

Research program to develop and validate conceptual models for flow and transport through unsaturated, fractured rock

International Nuclear Information System (INIS)

Glass, R.J.; Tidwell, V.C.

1991-01-01

As part of the Yucca Mountain Project, our research program to develop and validate conceptual models for flow and transport through unsaturated fractured rock integrates fundamental physical experimentation with conceptual model formulation and mathematical modeling. Our research is directed toward developing and validating macroscopic, continuum-based models and supporting effective property models because of their widespread utility within the context of this project. Success relative to the development and validation of effective property models is predicated on a firm understanding of the basic physics governing flow through fractured media, specifically in the areas of unsaturated flow and transport in a single fracture and fracture-matrix interaction. 43 refs

Research program to develop and validate conceptual models for flow and transport through unsaturated, fractured rock