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Laboratory investigations  

International Nuclear Information System (INIS)

Our task is to design mined-repository systems that will adequately secure high-level nuclear waste for at least 10,000 yr and that will be mechanically stable for 50 to 100-yr periods of retrievability during which mistakes could be corrected and a valuable source of energy could be reclaimed, should national policy on the reprocessing of spent fuel ever change. The only credible path for the escape of radionuclides from the repository to the biosphere is through ground-water, and in hard rock, bulk permeability is largely governed by natural and artificial fracture systems. Catastrophic failure of an excavation in hard rock is likely to occur at the weakest links - the discontinuities in the rock mass that is perturbed first by mining and then by radiogenic heating. The laboratory can contribute precise measurements of the pertinent thermomechanical, hydrological and chemical properties and improve our understanding of the fundamental processes through careful experiments under well controlled conditions that simulate the prototype environment. Thus laboratory investigations are necessary, but they are not sufficient, for conventional sample sizes are small relative to natural defects like joints - i.e., the rock mass is not a continuum - and test durations are short compared to those that predictive modeling must take into account. Laboratory investigators can contribute substantially more useful data if they are provided facilities for testing large specimens(say one cubic meter) and for creep testing of all candidate host rocks. Even so, extrapolations of laboratory data to the field in neither space nor time are valid without the firm theoretical foundations yet to be built. Meanwhile in-situ measurements of structure-sensitive physical properties and access to direct observations of rock-mass character will be absolutely necessary

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The research-based laboratory versus the traditional laboratory: An investigation of students' understanding of nature of experiments and experimental design  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study investigated similarities and differences between students’ experience in the research-based and traditional laboratory. The goal was to determine if the students’ laboratory experience influenced their understanding of the nature of experiments and experimental design. The data suggest that the students’ experiences differed between the laboratories, which resulted in students reporting different learning gains. The data support the idea that the research-based laboratory is...

Green, Kellie Flonesha Marie

2010-01-01

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Experimental investigation of laboratory-scale rocket engine fed on solid polyethylene rod as fuel  

Science.gov (United States)

Fire testing of the laboratory-scale rocket engine with the consumable solid polyethylene rod as fuel is described. The experimental data on heat flows, gasification rate and heat transfer coefficient are presented. Results of the testing may be useful for designing launch vehicles with combustible polyethylene tank shells.

Yemets, V. V.; Sanin, F. P. Dzhur, Ye. O.; Masliany, M. V.; Kostritsyn, O. Yu.; Minteev, G. V.; Ushkanov, V. M.

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Experimental Investigation of Multibunch, Multipass Beam Breakup in the Jefferson Laboratory Free Electron Laser Upgrade Driver  

Energy Technology Data Exchange (ETDEWEB)

In recirculating accelerators, and in particular energy recovery linacs (ERLs), the maximum current can be limited by multipass, multibunch beam breakup (BBU), which occurs when the electron beam interacts with the higher-order modes (HOMs) of an accelerating cavity on the accelerating pass and again on the energy recovering pass. This effect is of particular concern in the design of modern high average current energy recovery accelerators utilizing superconducting RF technology. Experimental characterization and observations of the instability at the Jefferson Laboratory 10 kW Free Electron Laser (FEL) are presented. Measurements of the threshold current for the instability are made under a variety of beam conditions and compared to the predictions of several BBU simulation codes. This represents the first time in which the codes have been experimentally benchmarked. With BBU posing a threat to high current beam operation in the FEL Driver, several suppression schemes were developed.

Christopher Tennant; David Douglas; Kevin Jordan; Nikolitsa Merminga; Eduard Pozdeyev; Haipeng Wang; Todd I. Smith; Stefan Simrock; Ivan Bazarov; Georg Hoffstaetter

2006-03-24

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Experimental Investigation of Beam Breakup in the Jefferson Laboratory 10 kW FEL Upgrade Driver  

CERN Document Server

In recirculating accelerators, and in particular energy recovery linacs (ERLs), the maximum current has been limited by multipass, multibunch beam breakup (BBU), which occurs when the electron beam interacts with the higher-order modes (HOMs) of an accelerating cavity on the accelerating pass and again on the energy recovered pass. This effect is of particular concern in the design of modern high average current energy recovery accelerators utilizing superconducting technology. Experimental observations of the instability at the Jefferson Laboratory 10 kW Free-Electron Laser (FEL) are presented. Measurements of the threshold current for the instability are presented and compared to the predictions of several BBU simulation codes. To further characterize the instability, beam based measurements were made to determine the orientation of the dangerous HOMs. With BBU posing a threat to high current beam operation in the FEL, several suppression schemes were developed. These include direct damping of the dangerous...

Tennant, Chris; Douglas, David; Hoffstaetter, Georg Heinz; Jordan, Kevin; Merminga, Lia; Pozdeyev, Eduard; Simrock, Stefan; Smith, Todd I; Wang, Haipeng

2005-01-01

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Experimental investigation of Hover flowfields in water at the McDonnell Douglas Research Laboratories  

Science.gov (United States)

A new experimental facility, the Hover Research Facility (HRF), is designed to study the flowfields generated by hovering vertical takeoff and landing (VTOL) aircraft and helicopters. Water is used as the working medium because of its inherent advantages in flow visualization and laser Doppler velocimeter (LDV) measurements. The applications of the Hover Research Facility include: (1) experimental investigation of twin-jet impingement flow with application to VTOL aircraft; (2) visualization of the flowfield around a fully contoured, model supersonic fighter/attack short takeoff and vertical landing (STOVL) aircraft; and (3) performance testing of a No Tail Rotor (NOTAR) helicopter in hover mode by use of a scale model. Flow visualization and quantitative LDV data on these experiments are presented.

Saripalli, K. R.; Kroutil, J. C.; Vanhorn, J. R.

1987-06-01

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Laboratory Experimentation in Economics  

Directory of Open Access Journals (Sweden)

Full Text Available Experimental economics is the application of experimental methods to study economic questions. Data collected in experiments are used to estimate effect size, test the validity of economic theories, and illuminate market mechanisms. Economic experiments usually use cash to motivate subjects, in order to mimic real-world incentives. Experiments are used to help understand how and why markets and other exchange systems function as they do. A fundamental aspect of the subject is design of experiments. Experiments may be conducted in the field or in laboratory settings, whether of individual or group behavior. Variants of the subject outside such formal confines include natural and quasi-natural experiments.

Dimitrios Koumparoulis

2013-02-01

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A Laboratory Investigation of Supersonic Clumpy Flows: Experimental Design and Theoretical Analysis  

CERN Document Server

We present a design for high energy density laboratory experiments studying the interaction of hypersonic shocks with a large number of inhomogeneities. These ``clumpy'' flows are relevant to a wide variety of astrophysical environments including the evolution of molecular clouds, outflows from young stars, Planetary Nebulae and Active Galactic Nuclei. The experiment consists of a strong shock (driven by a pulsed power machine or a high intensity laser) impinging on a region of randomly placed plastic rods. We discuss the goals of the specific design and how they are met by specific choices of target components. An adaptive mesh refinement hydrodynamic code is used to analyze the design and establish a predictive baseline for the experiments. The simulations confirm the effectiveness of the design in terms of articulating the differences between shocks propagating through smooth and clumpy environments. In particular, we find significant differences between the shock propagation speeds in a clumpy medium comp...

Poludnenko, A Y; Drake, R P; Frank, A; Knauer, J P; Meyerhofer, D D; Furnish, M; Asay, J R

2004-01-01

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An experimental investigation of reacting and nonreacting coaxial jet mixing in a laboratory rocket engine  

Science.gov (United States)

Coaxial jets are commonly used as injectors in propulsion and combustion devices due to both the simplicity of their geometry and the rapid mixing they provide. In liquid rocket engines it is common to use coaxial jets in the context of airblast atomization. However, interest exists in developing rocket engines using a full flow staged combustion cycle. In such a configuration both propellants are injected in the gaseous phase. In addition, gaseous coaxial jets have been identified as an ideal test case for the validation of the next generation of injector modeling tools. For these reasons an understanding of the fundamental phenomena which govern mixing in gaseous coaxial jets and the effect of combustion on these phenomena in coaxial jet diffusion flames is needed. A study was performed to better understand the scaling of the stoichiometric mixing length in reacting and nonreacting coaxial jets with velocity ratios greater than one and density ratios less than one. A facility was developed that incorporates a single shear coaxial injector in a laboratory rocket engine capable of ten atmospheres. Optical access allows the use of flame luminosity and laser diagnostic techniques such as Planar Laser Induced Fluorescence (PLIF). Stoichiometric mixing lengths (LS), which are defined as the distance along the centerline where the stoichiometric condition occurs, were measured using PLIF. Acetone was seeded into the center jet to provide direct PLIF measurement of the average and instantaneous mixture fraction fields for a range of momentum flux ratios for the nonreacting cases. For the coaxial jet diffusion flames, LS was measured from OH radical contours. For nonreacting cases the use of a nondimensional momentum flux ratio was found to collapse the mixing length data. The flame lengths of coaxial jet diffusion flames were also found to scale with the momentum flux ratio but different scaling constants are required which depended on the chemistry of the reaction. The effective density ratio was measured which allowed the flame lengths to be collapsed to the nonreacting scaling relation. The equivalence principle of Tacina and Dahm was utilized to compare the theoretical and measured effective density ratios.

Schumaker, Stephen Alexander

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Experimental investigation of the interaction of clays with high pH solutions: A case study from the Callovo-Oxfordian formation, Meuse - Haute Marne underground laboratory (France)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The impact of alkaline solutions (pH = 13.2) on the clay mineralogy of the CallovoOxfordian formation hosting the French underground laboratory for nuclear waste disposal investigation (Meuse-Haute Marne site) has been studied experimentally. Initially, each of the four samples selected as representative of the mineralogical transition in this CallovoOxfordian formation consist of a mixture of three main clay phases: discrete illite, discrete smectite and a randomly interstratified mixed laye...

Claret, Francis; Bauer, Andreas; Scha?fer, Thorsten; Griffault, Lise; Lanson, Bruno

2002-01-01

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3D PiC code simulations for a laboratory experimental investigation of Auroral Kilometric Radiation mechanisms  

International Nuclear Information System (INIS)

Auroral Kilometric Radiation (AKR), occurs naturally in the polar regions of the Earth's magnetosphere where electrons are accelerated by electric fields into the increasing planetary magnetic dipole. Here conservation of the magnetic moment converts axial to rotational momentum forming a horseshoe distribution in velocity phase space. This distribution is unstable to cyclotron emission with radiation emitted in the X-mode. In a scaled laboratory reproduction of this process, a 75-85 keV electron beam of 5-40 A was magnetically compressed by a system of solenoids and emissions were observed for cyclotron frequencies of 4.42 GHz and 11.7 GHz resonating with near cut-off TE0,1 and TE0,3 modes, respectively. Here we compare these measurements with numerical predictions from the 3D PiC code KARAT. The 3D simulations accurately predicted the radiation modes and frequencies produced by the experiment. The predicted conversion efficiency between electron kinetic and wave field energy of around 1% is close to the experimental measurements and broadly consistent with quasi-linear theoretical analysis and geophysical observations.

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Experimental investigation of the formation and propagation of plasma jets created by a power laser: application to laboratory astrophysics  

International Nuclear Information System (INIS)

Plasma jets are often observed in the polar regions of Young Stellar Objects (YSO). For a better understanding of the whole processes at the origin of their formation and evolution, this research thesis aims at demonstrating the feasibility of a plasma jet generation by a power laser, and at investigating its characteristics. After a detailed description of Young Stellar Objects jets and an overview of theoretical models, the author describes some experiments performed with gas guns, pulsed machines and power lasers. He describes means of generation of a jet by laser interaction via strong shock propagation. He reports experimental work, describing the target, laser operating conditions and the determination of jet parameters: speed, temperature, density. Then, he introduces results obtained for plasma jet propagation in vacuum, describes their evolution with respect to initial conditions (target type, laser operating conditions), and identifies optimal conditions for generating a jet similar to that in astrophysical conditions. He considers their propagation in ambient medium like for YSO jets in interstellar medium. Two distinct cases are investigated: collision of two successive shocks in a gaseous medium, and propagation of a plasma jet in a gas jet

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An Experimental Investigation of the Role of Radiation in Laboratory Bench-Top Experiments in Thermal Physics  

Science.gov (United States)

A simple undergraduate experiment designed to study cooling purely by radiation and cooling by a combination of convection and radiation is described. Results indicate that the contribution from radiative cooling in normal laboratory experiments is more significant than students often realize, even in the case of forced cooling. (Contains 1…

Twomey, Patrick; O'Sullivan, Colm; O'Riordan, John

2009-01-01

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Experimental Investigations of the Existence of a Local-Time Effect on the Laboratory Scale and the Heterogeneity of Space-Time  

Directory of Open Access Journals (Sweden)

Full Text Available The main subject of this work is an experimental investigation of the existence of a local-time effect on the laboratory scale, i.e. longitudinal distances between locations of measurements from one metre to tens of metres. A short review of our investigations of the existence of a local-time effect for longitudinal distances from 500 m to 15 km is also presented. Besides investigations of the minimal spatial scale for a local-time effect, the paper presents investigations of the effect in the time domain. In this relation the structure of intervals distribution in the neighbourhood of local-time peaks was studied and splitting of the peaks was revealed. Further investigations revealed second order splitting of local-time peaks. From this result it is concluded that space-time heterogeneity, which follows from the local-time effect, probably has fractal character. The results lead to the conclusion of sharp anisotropy of space-time.

Shnoll S.E.

2007-01-01

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Lindhurst Laboratory of Experimental Geophysics  

Science.gov (United States)

This Web site illustrates the California Institute of Technology's Lindhurst Laboratory of Experimental Geophysics research in dynamic compressions of minerals. The site describes how seismologists became interested in the physical properties of minerals within the high pressure and high temperature environment of the Earth's interior. With a series of images and figures of the shock wave equipment and the schematic of the VISAR setup, students and educators can learn about their current research in shock loading and impact. The site also provides links to the staff's research where scientists can find out about studies in thermodynamical models of impact-induced vaporization, laser ablation-ionization, Time-of-Flight Mass Spectrometry (TOFMS), and more.

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Experimental investigations on desiccant wheels  

International Nuclear Information System (INIS)

Experimental investigations on several commercially available and newly fabricated rotors are conducted in two different laboratories to evaluate performance trends. Experimental uncertainties are analysed and the parameters determining the rotor performance are investigated. It is found that the optimal rotation speed is lower for lithium chloride or compound rotors than for silica gel rotors. Higher regeneration air temperatures lead to higher dehumidification potentials at almost equal dehumidification efficiencies, but with increasing regeneration specific heat input and enthalpy changes of the process air. The influence of the regeneration air humidity was also notable and low relative humidities increase the dehumidification potential. Finally, the measurements show that rising water content in the ambient air causes the dehumidification capacity to rise, while the dehumidification efficiency is not much affected and both specific regeneration heat input and latent heat change of the process air decrease. For desiccant cooling applications in humid climates this is a positive trend. - Highlights: ? New experimental results on a range of desiccant wheels. ? High dehumidification capacities and low enthalpy changes for process air high water content. ? Higher regeneration temperature increases capacity, but lowers energy efficiency.

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Experimental Simulation in the Modern Physics Laboratory.  

Science.gov (United States)

Described are graphic computer simulations of laboratory experiments in modern physics developed for student use prior to each laboratory and which replace pre-lab briefing. Experimental simulation is intended to familiarize the students with the experiment, and to allow the students to try a larger number of "experimental" combinations of…

Wilson, Jack M.

1980-01-01

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Investigations of Polymorphic Germylene Structures, Experimental Calculations of a New Boron-Sulfur Heterocycle and Assessment of a Safety Curriculum in an Undergraduate Laboratory  

Science.gov (United States)

The dynamic interaction between chemistry and humankind is explored via investigations with benign substrates and the incorporation of proper laboratory technique instruction to a general audience. This intersection will be discussed in further detail in the introductory chapter of this thesis. The second chapter of this thesis describes the determination of two polymorphic structures from relatively non-toxic Cp*GeCl. The investigation of the polymorphic stability led to discovery of a solution equilibrium between monomeric and dimeric or higher oligomeric species. These experiments revealed the conversion of polymorphic structures in solid state and solution, allowing a thorough exploration of the thermodynamic and kinetic stability of each of the polymorphic structures. The third chapter of this dissertation describes computational analysis of the aromaticity of the recently prepared boron heterocycle, 2-diiosopropylamino-2 H-1,2-thiaborin. The importance and potential utility of aromatic boron-containing heterocycles in electronic devices and hydrogen storage is discussed. The theory behind computational chemistry and the analysis of the aromaticity, HOMO/LUMO, and nuclear magnetic resonance shifts of 2-diiosopropylamino-2 H-1,2-thiaborin are also reported. NICS (1) calculations determined that external pi-interactions of the external amino substituent greatly decrease the aromaticity of the parent ring. The fourth chapter describes the development and analysis of the effectiveness of a chemical hygiene-based laboratory curriculum incorporated in the University of Michigan undergraduate organic chemistry laboratory course, Chemistry 211. There is a great need to educate the general population of undergraduates enrolled in lower-division organic chemistry courses at the University of Michigan and in other universities in chemical hygiene. Previous laboratory curricula lacked in-depth discussions on proper laboratory practices. Through weekly reading assignments, quizzes, colorful posters and other educational materials, the students were exposed to information about chemical safety. Surveys and in-class observations were used to analyze the effectiveness of the newly instituted curriculum. The results from this study indicate that teaching the students and the graduate student instructors chemical hygiene can decrease the overall number of laboratory accidents and increase awareness of chemical safety.

Rohr Daniel, Ahleah

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Experimental investigation of soil filtration using geotextiles  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The doctoral research is a study of soil filtration by geotextile fabrics, with the ultimate objective of improving design and long-term performance of underdrain systems in highways.^ The experimental investigation was conducted in the laboratory using the best available techniques, the Flexible Wall Gradient Ratio Test and the Rapid Retention Test, in order to assess soil-filter compatibility and monitor geotextile clogging, for a range of materials and testing conditions. Field informati...

Lee, Sang-ho

2006-01-01

20

[Hemorheological investigations in experimental surgery].  

Science.gov (United States)

The hemorheological parameters, such as whole blood viscosity, plasma viscosity, hematocrit, fibrinogen concentration as well as the micro-rheological properties of red blood cells (red blood cell deformability and aggregation) play an important role in tissue perfusion. The alternating hemorheological parameters, which are also inter-related, have important effects in determining hemodynamical properties, as well. The altered hemorheological status has a direct effect on endothelial function by changing shear force profile on the endothelial wall, and impairment of red blood cell deformability and aggregation (presence of rigid red blood cell, and enhanced red blood cell aggregation) slows down microcirculation with disturbing capillary perfusion. In experimental surgery vascular clamping and release cause ischemia-reperfusion, which affect red blood cells in many ways: changes pH level, leads to free-radical release, changes osmolarity and lactate and NO concentrations as well as it causes mechanical trauma. Understanding of these pathophysiological processes and determining the extent of reversible-irreversible changes may help to delineate underlying causes in tissue perfusion and microcirculation better, and develop prophylactic and therapeutic possibilities. The challenges of experimental surgery also include the questions of comparability in different measurement methods, and understanding of interspecies-differences of experimental/laboratory animal models in order to increase the relevance of results in terms of applicability for the original, clinical question. PMID:23782604

Németh, Norbert; Kiss, Ferenc; Furka, István; Mikó, Irén

2013-06-01

 
 
 
 
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Laboratory investigation of Acanthamoeba keratitis.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Following the diagnosis of Acanthamoeba keratitis in a contact lens wearer, the antimicrobial susceptibility of the clinical isolate and the environmental source of the infection were investigated. Contrary to previous reports, in vitro antimicrobial testing showed that the infecting strain was inherently resistant to propamidine isethionate. Restriction endonuclease digestion analysis of Acanthamoeba whole-cell DNA of strains isolated from the patient's cornea, contact lens storage container...

Kilvington, S.; Larkin, D. F.; White, D. G.; Beeching, J. R.

1990-01-01

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Laboratory investigation of primary aldosteronism.  

Science.gov (United States)

Availability and wider application of the plasma aldosterone/renin ratio (ARR) as a screening test for primary aldosteronism (PA) has led to the recognition that PA is the most common potentially curable and specifically treatable form of hypertension, possibly accounting for as many as 5-13% of patients. Aldosterone excess also has adverse cardiovascular consequences that go above and beyond hypertension development. These findings support the concept that PA plays an important role in cardiovascular disease states and should be systematically sought and specifically treated, and have led to the development of a US Endocrine Society clinical guideline for the detection, diagnosis and management of this condition. Reliable detection requires that interfering factors (including medications known to alter the ratio) are controlled before ARR measurement (or their effects taken into account), and reliable methods such as fludrocortisone suppression testing are used to confirm PA. Because computed tomography frequently misses aldosterone-producing adenomas yet demonstrates non-functioning nodules, adrenal venous sampling is the only dependable way to differentiate unilateral (surgically correctable) from bilateral (usually treated with aldosterone antagonist medications) forms of PA. For the glucocorticoid-remediable form of PA (familial hyperaldosteronism type I), genetic testing for the causative 'hybrid' 11beta-hydroxylase/aldosterone synthase gene has greatly facilitated detection. Laboratory assessment (including suppression testing post-operatively, and renin measurement during treatment with aldosterone antagonist medications) can assist in assessing therapeutic responses and in guiding ongoing management. Development of new, highly reliable high-throughput mass spectrometric methods for measuring aldosterone and renin should further enhance detection and reliability of diagnostic workup for PA. PMID:20498828

Stowasser, Michael; Taylor, Paul J; Pimenta, Eduardo; Ahmed, Ashraf H Al-Asaly; Gordon, Richard D

2010-05-01

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Experimental investigation of cavity flows  

Energy Technology Data Exchange (ETDEWEB)

This thesis uses LDV (Laser Doppler Velocimetry), PIV (Particle Image Velocimetry) and Laser Sheet flow Visualisation to study flow inside three different cavity configurations. For sloping cavities, the vortex structure inside the cavities is found to depend upon the flow direction past the cavity. The shape of the downstream corner is a key factor in destroying the boundary layer flow entering the cavity. The experimental results agree well with numerical simulations of the same geometrical configurations. The results of the investigations are used to find the influence of the cavity flow on the accuracy of the ultrasonic flowmeter. A method to compensate for the cavity velocities is suggested. It is found that the relative deviation caused by the cavity velocities depend linearly on the pipe flow. It appears that the flow inside the cavities should not be neglected as done in the draft for the ISO technical report on ultrasonic flowmeters. 58 refs., 147 figs., 2 tabs.

Loeland, Tore

1998-12-31

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Emissions from waste combustion. An application of statistical experimental design in a laboratory-scale boiler and an investigation from large-scale incineration plants  

Energy Technology Data Exchange (ETDEWEB)

The aim of this thesis is a study of the emissions from the combustion of household refuse. The experiments were both on a laboratory-scale boiler and on full-scale incineration plants. In the laboratory, an artificial household refuse with known composition was fed into a pilot boiler with a stationary grate. Combustion was under non-optimum conditions. Direct sampling with a Tenax adsorbent was used to measure a range of VOCs. Measurements were also made of incompletely burnt hydrocarbons, carbon monoxide, carbon dioxide, oxygen and flue gas temperature. Combustion and emission parameters were recorded continuously by a multi-point data logger. VOCs were analysed by gas chromatography and mass spectrometry (GC/MS). The full-scale tests were on seven Swedish incineration plants. The data were used to evaluate the emissions from large-scale incineration plants with various type of fuels and incinerators, and were also compared with the laboratory results. The response surface model developed from the laboratory experiments was also validated. This thesis also includes studies on the gasification of household refuse pellets, estimations of particulate and soot emissions, and a thermodynamic analysis of PAHs from combustion flue gas. For pellet gasification, experiments were performed on single, well characterised refuse pellets under carefully controlled conditions. The aim was to see if the effects of pellets were different from those of untreated household refuse. The results from both laboratory and full-scale tests showed that the main contributions to emissions from household refuse are plastics and moisture. 142 refs, 82 figs, 51 tabs

Zhang Xiaojing

1997-05-01

25

A Discovery Laboratory Investigating Bacterial Gene Regulation  

Science.gov (United States)

This laboratory exercise introduces students to experimental design and gene regulation using different sugar ("food" sources) and an enzyme assay for beta-glalctosidase to identify different E. coli stains with respect to lac operon mutations, then designing their own experiments to study the various aspects of the lac operon.

Robert Moss (Wofford College;)

1999-01-01

26

Investigations for a Mobile Environmental Education Laboratory.  

Science.gov (United States)

Envirpnmental investigations in this compilation were developed in conjunction with the establishment of a mobile environmental education laboratory, a demonstration project of the Kingsport (Tennessee) City School System. The 50 activities are divided into five categories: basic resources, environmental problems, living organisms, community…

Childress, Ronald B.

27

Experimental investigation of wave boundary layer  

DEFF Research Database (Denmark)

A review is presented of experimental investigation of wave boundary layer. The review is organized in six main sections. The first section describes the wave boundary layer in a real-life environment and its simulation in the laboratory in an oscillating water tunnel and in a water tank with an oscillating seabed. A brief account is given of measured quantities, measurement techniques (LDA, PIV, flow visualization) and limitations/constraints in the experimental investigation of the wave boundary layer in the laboratory. The second section concentrates on uniform oscillating boundary layers with a smooth bed. The boundary layer process is described over the entire range of the Reynolds number (Re from practically nil to Re = O(107)), from the laminar regime to the transitional regime and to the fully developed turbulent regime. The third section focuses on the effect of the boundary roughness. Results of recent research on wave boundary layers over a bed with large roughness (such as a/ks = O(1)) are also included in the review. The fourth section describes the effect of superimposed current on the wave boundary layer. The entire ¿spectrum¿, namely from the wave-dominated regime to the current-dominated regime, is covered. Processes such as turbulence reduction/re-laminarization, and increase/decrease in the bed shear stress are presented. The fifth section considers various effects on the wave boundary layer such as the non-uniformity (that due to change in the boundary roughness and that due to change in the flow geometry, i.e., the divergent/convergent environment); irregular waves, the angle of attack of waves; the effect of an externally generated field of turbulence; the suction and injection at the boundary (the ventilated boundary layers); and the vegetation. Also a brief account is given of the steady streaming (in a progressive wave and in a standing wave). The final section summarizes the results of recent research on coherent structures in wave boundary layers.

Sumer, B. Mutlu

2003-01-01

28

Vortex meter designing: Simulation or laboratory investigations?  

Science.gov (United States)

Considerations concerned the problem pointed out in the title of the article are presented. Results of laboratory investigations of the vortex shedding phenomenon, with application of various research methods are described. During the tests the specific discoveries of the phenomenon properties were made. In the article the problems and threats related to the numerical simulation of von Karman vortex street phenomenon are discussed. Conditions of successful numerical simulation are specified.

Pankanin, Grzegorz L.

2013-10-01

29

Experimental investigation of piloted flameholders  

Science.gov (United States)

Four configurations of piloted flameholders were tested. The range of flame stabilization, flame propagation, pressure oscillation during ignition, and pressure drop of the configurations were determined. Some tests showed a very strong effect of inlet flow velocity profile and flameholder geometry on flame stabilization. These tests led to the following conclusions. (1) The use of a piloted flameholder in the turbofan augmentor may minimize the peak pressure rise during ignition. At the present experimental conditions, delta P/P asterisk over 2 is less than 10 percent; therefore, the use of a piloted flameholder is a good method to realize soft ignition. (2) The geometry of the piloted flameholder and the amount of fuel injected into the flameholder have a strong effect on the pressure oscillation during ignition of the fuel-air mixture in the secondary zone. (3) Compared with the V-gutter flameholder with holes in its wall, the V-gutter flameholder without holes not only has advantages such as simple structure and good rigidity but offers a wide combustion stability limit and a high capability of igniting the fuel-air mixture of the secondary zone.

Guo, C. F.; Zhang, Y. H.; Xie, Q. M.

1986-01-01

30

Analytical and experimental investigation of soil reinforcing  

Science.gov (United States)

Significant improvements in the capacity and service life of reinforced earth structures require an improved understanding of the fundamental behavior of these systems. Both experimental and analytical investigations were carried out to develop models for the interaction of geotextile-type reinforcement and granular soils. Reinforcement configurations and systems investigated were thought to be applicable to alternate launch and recovery surfaces (ALRS). Model ALRS systems using geotextiles and geogrids as reinforcement were tested in the laboratory in a variety of configurations. These were loaded to failure, quasi-statically, by both plane strain and axisymmetric rigid plates. Load-deformation characteristics as well as the shape of the deflected basin are reported. Significant increases in bearing capacity and modulus of subgrade reaction as a function of depth and number of layers of reinforcement were observed. However, there was a decrease in improvement as the depth to the first layer increased. Edge fixity conditions were found to be relatively unimportant, and the benefit of multiple-reinforcement layers was greater if the depth and spacing were small compared to the diameter of the loaded area. Surprisingly, little difference was observed in the response of the geogrids and geotextiles, probably because sand was used in the experiments. Geometric scaling of bearing capacity, based on the diameters of the loaded areas, was not possible.

Holtz, R. D.; Harr, M. E.

1983-10-01

31

Laboratory Investigations of Stratospheric Halogen Chemistry  

Science.gov (United States)

A final report for the NASA-supported project on laboratory investigations of stratospheric halogen chemistry is presented. In recent years, this project has focused on three areas of research: (1) kinetic, mechanistic, and thermochemical studies of reactions which produce weakly bound chemical species of atmospheric interest; (2) development of flash photolysis schemes for studying radical-radical reactions of stratospheric interest; and (3) photochemistry studies of interest for understanding stratospheric chemistry. The first section of this paper contains a discussion of work which has not yet been published. All subsequent chapters contain reprints of published papers that acknowledge support from this grant.

Wine, Paul H.; Nicovich, J. Michael; Stickel, Robert E.; Hynes, Anthony J.

1997-01-01

32

Laboratory investigations of impact-generated plasma  

Science.gov (United States)

The characteristics of plasma that was produced in laboratory by hypervelocity impacts were investigated to demonstrate the feasibility of generation of magnetic fields by meteoritic impacts and to explain the presence of paleomagnetic fields on the lunar surface. The impact-generated magnetic fields were found to exhibit spatial and temporal complexity that depended on the impact angle, the velocity, and the projectile/target composition. The results suggest that crater-related paleomagnetism associated with this mechanism should exhibit similar complexity with spatial wavelengths on the order of a fraction of the crater radius.

Crawford, David A.; Schultz, Peter H.

1991-01-01

33

Experimental investigation of hydrogen cryogenic distillation process  

International Nuclear Information System (INIS)

Full text: Research conducted in the last fifty years has shown that one of the most efficient techniques of removing tritium from the heavy water used as moderator and coolant in CANDU reactors (as that operated at Cernavoda, Romania) is the hydrogen cryogenic distillation. Designing and implementing the concept of cryogenic distillation column require experiments to be conducted as well as computer simulations. Particularly, computer simulations are of great importance in designing and evaluating the performances of a column or a series of columns. Experimental data obtained from laboratory work will be used as input for computer simulations run at larger scale (namely for the and Deuterium Separation Pilot Plant). Studies carried out were focused on the following items: - optimizing important parameters such as the number of theoretical plates, inlet area, reflux flow, flow-rates extraction, working pressure, etc; - the way of connecting the columns in series to fulfil the separation requirements. Experiments were performed on a bench-scale installation to investigate the performances of contact elements with continuous packages. The packages were manufactured in our institute. (authors)

34

Experimental investigation of new neutron moderator materials  

Energy Technology Data Exchange (ETDEWEB)

In this study we present experimental investigation of thermal neutron energy spectra produced by lead and bismuth hydroxides (Pb(OH){sub 2}, and Bi(OH){sub 3}). The experimental energy spectra are compared with a thermal neutron energy spectrum of water measured in the same geometry. We present an MCNPX geometry model used to help with the experimental data interpretation. We demonstrate a very good reproduction of the experimental thermal neutron energy spectrum produced by the water moderator. We show a sensitivity study with the Pb(OH){sub 2}, and Bi(OH){sub 3} materials on different combinations of thermal neutron scattering kernels.

Mocko, Michal [Los Alamos National Laboratory; Daemen, Luke L [Los Alamos National Laboratory; Hartl, Monika [Los Alamos National Laboratory; Huegle, Thomas [Los Alamos National Laboratory; Muhrer, Guenter [Los Alamos National Laboratory

2010-01-01

35

EXPERIMENTAL RESPIRATORY CARCINOGENESIS IN SMALL LABORATORY ANIMALS  

Science.gov (United States)

Studies designed to test the ability of environmental pollutants to induce lung cancer in experimental animals by chronic inhalation exposure are summarized in this review. The studies are limited to those published in peer-reviewed journals and may not include all experiments co...

36

Preliminary rock mechanics laboratory: Investigation plan  

International Nuclear Information System (INIS)

This document presents the rationale for rock mechanics laboratory testing (including the supporting analysis and numerical modeling) planned for the site characterization of a nuclear waste repository in salt. This plan first identifies what information is required for regulatory and design purposes, and then presents the rationale for the testing that satisfies the required information needs. A preliminary estimate of the minimum sampling requirements for rock laboratory testing during site characterization is also presented. Periodic revision of this document is planned

37

Preliminary rock mechanics laboratory: Investigation plan  

Energy Technology Data Exchange (ETDEWEB)

This document presents the rationale for rock mechanics laboratory testing (including the supporting analysis and numerical modeling) planned for the site characterization of a nuclear waste repository in salt. This plan first identifies what information is required for regulatory and design purposes, and then presents the rationale for the testing that satisfies the required information needs. A preliminary estimate of the minimum sampling requirements for rock laboratory testing during site characterization is also presented. Periodic revision of this document is planned.

Oschman, K.P.; Hummeldorf, R.G.; Hume, H.R.; Karakouzian, M.; Vakili, J.E.

1987-01-01

38

Fusion of Laboratory and Textual Data for Investigative Bioforensics  

Energy Technology Data Exchange (ETDEWEB)

Chemical and biological forensic programs focus on the identification of a threat and acquisition of laboratory measurements to determine how a threat agent may have been produced. However, to generate investigative leads, it might also be useful to identify institutions where the same agent has been produced by the same or a very similar process, since the producer of the agent may have learned methods at a university or similar institution. We have developed a Bayesian network framework that fuses hard and soft data sources to assign probability to production practices. It combines the results of laboratory measurements with an automatic text reader to scan scientific literature and rank institutions that had published papers on the agent of interest in order of the probability that the institution has the capability to generate the sample of interest based on laboratory data. We demonstrate the Bayesian network on an example case from microbial forensics, predicting the methods used to produce Bacillus anthracis spores based on mass spectrometric measurements and identifying institutions that have a history of growing Bacillus spores using the same or highly similar methods. We illustrate that the network model can assign a higher posterior probability than expected by random chance to appropriate institutions when trained using only a small set of manually analyzed documents. This is the first example of an automated methodology to integrate experimental and textual data for the purpose of investigative forensics.

Webb-Robertson, Bobbie-Jo M.; Corley, Courtney D.; McCue, Lee Ann; Wahl, Karen L.; Kreuzer, Helen W.

2013-03-10

39

Protocol and material for the introduction to the laboratory experimentation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Introducing students in the world of the experimentation has always been a complicated task, since the students are not familiar with the new work place. They have to handle different measuring devices, interiorize the philosophy of the experimentation, measure and estimate uncertainty, graph data, and finally write a report about the results of the experimentation. Students do not know this whole process, and although they delight to do practical work in the laboratory, they do not ...

Ferreres Soler, Enriqueta; Conangla Trivin?o, Laura; Mercade? Capellades, Juan Mari?a; Jorge Sa?nchez, Juan

2009-01-01

40

Experimental investigation of fuel-coolant interaction  

International Nuclear Information System (INIS)

An experimental investigation of thermal interaction of molten metals with cold liquids was made using measurements of transient temperature, pressure, and reactive force; postexperiment microscopic, metallographic, and chemical investigations completed the results. Thermal explosion, film boiling, and inverse Leidenfrost phenomena were considered. The origin of ''jets'' of small particles from the main particle was found to be a triggering mechanism of thermal explosion. Thermal explosion can be a phenomenon of coupled fragmentation and vapor explosion. Fast solidification was recognized as the main process that influenced fragmentation of the hot metal

 
 
 
 
41

Vibrations of twisted cantilevered plates - Experimental investigation  

Science.gov (United States)

The experimental portion of a joint government/industry/university research study on the vibrational characteristics of twisted cantilevered plates is presented. The overall purpose of the research study was to assess the capabilities and limitations of existing analytical methods in predicting the vibratory characteristics of twisted plates. Thirty cantilevered plates were precision machined at the Air Force's Aero Propulsion Laboratory. These plates, having five different degrees of twist, two thicknesses, and three aspect ratios representative of turbine engine blade geometries, were tested for their vibration mode shapes and frequencies. The resulting nondimensional frequencies and selected mode shapes are presented as a function of plate tip twist. The trends of the natural frequencies as a function of the governing geometric parameters are discussed. The effect of support compliance on the plate natural frequency and its impact on numerically modeling twisted plates is also presented.

Macbain, J. C.; Kielb, R. E.; Leissa, A. W.

1984-01-01

42

A LABORATORY SYSTEM FOR INVESTIGATING SUBSYNCHRONOUS RESONANCE  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The problem of subsynchronous resonance (SSR) instability in power systems containing long capacitively compensated transmission lines has recently attracted much attention. The laboratory system was designed to model as closely as possible the new nuclear powered turbo-generators to be installed at Koeberg power station in South Africa. The theory describing the system dynamics is presented briefly. The designs of the distributed mass system and of a novel type of shaft twist transducer are ...

Limebeer, D.; Harley, R.; Lahoud, M.

1980-01-01

43

Laboratory Investigation of Asteroid Regolith Properties  

Science.gov (United States)

We are beginning a three-year effort to study regolith properties and processes on low - gravity, small asteroids by conducting analog experiments with cohesive powders in a 1-g laboratory environment. Our goal is to develop an improved understanding of the role of cohesion in affecting regolith processes and surface morphology of small Solar System bodies, some the targets of ongoing and proposed missions, and to quantify the range of expected mechanical properties of such regoliths.

Durda, D.; Devaud, G.; Scheeres, D.; Sánchez, P.; Roark, S.; Kaptchen, P.; Dissly, R.; Campo Bagatin, A.

2013-09-01

44

The European Network of Analytical and Experimental Laboratories for Geosciences  

Science.gov (United States)

Integrating Earth Sciences infrastructures in Europe is the mission of the European Plate Observing System (EPOS).The integration of European analytical, experimental, and analogue laboratories plays a key role in this context and is the task of the EPOS Working Group 6 (WG6). Despite the presence in Europe of high performance infrastructures dedicated to geosciences, there is still limited collaboration in sharing facilities and best practices. The EPOS WG6 aims to overcome this limitation by pushing towards national and trans-national coordination, efficient use of current laboratory infrastructures, and future aggregation of facilities not yet included. This will be attained through the creation of common access and interoperability policies to foster and simplify personnel mobility. The EPOS ambition is to orchestrate European laboratory infrastructures with diverse, complementary tasks and competences into a single, but geographically distributed, infrastructure for rock physics, palaeomagnetism, analytical and experimental petrology and volcanology, and tectonic modeling. The WG6 is presently organizing its thematic core services within the EPOS distributed research infrastructure with the goal of joining the other EPOS communities (geologists, seismologists, volcanologists, etc...) and stakeholders (engineers, risk managers and other geosciences investigators) to: 1) develop tools and services to enhance visitor programs that will mutually benefit visitors and hosts (transnational access); 2) improve support and training activities to make facilities equally accessible to students, young researchers, and experienced users (training and dissemination); 3) collaborate in sharing technological and scientific know-how (transfer of knowledge); 4) optimize interoperability of distributed instrumentation by standardizing data collection, archive, and quality control standards (data preservation and interoperability); 5) implement a unified e-Infrastructure for data analysis, numerical modelling, and joint development and standardization of numerical tools (e-science implementation); 6) collect and store data in a flexible inventory database accessible within and beyond the Earth Sciences community(open access and outreach); 7) connect to environmental and hazard protection agencies, stakeholders, and public to raise consciousness of geo-hazards and geo-resources (innovation for society). We will inform scientists and industrial stakeholders on the most recent WG6 achievements in EPOS and we will show how our community is proceeding to design the thematic core services.

Freda, Carmela; Funiciello, Francesca; Meredith, Phil; Sagnotti, Leonardo; Scarlato, Piergiorgio; Troll, Valentin R.; Willingshofer, Ernst

2013-04-01

45

Experimental investigation on the rheology of foams  

Energy Technology Data Exchange (ETDEWEB)

The rheology of foams was investigated using aqueous and gelled foams and employing a pipe-type viscometer. Surfactant at 0.5 per cent concentration was used as the foaming agent. Results indicated that foam fluid rheology can be adequately characterized by the Herschel-Bulkley model. The experimental data served as the starting point for the development of new empirical correlations to predict foam fluid apparent viscosity. The use of these new correlations is expected to provide more accurate estimates of foam fluid rheological properties. 14 refs., 5 tabs., 14 figs.

Bonilla, L. F. [Univ. Surcolombiana, Neiva, Huila (Colombia); Shah, S. N. [Oklahoma Univ., Norman, OK (United States)

2000-07-01

46

Experimental and numerical investigations of plasma turbulence  

International Nuclear Information System (INIS)

Turbulence in plasmas has been investigated experimentally and numerically. The work described here is divided into four parts: - experiments on edge turbulence in a single-ended Q-machine. Convective cells are investigated in detail together with the anomalous transport caused by them. - Numerical simulation of the edge turbulence in the Q-machine. This simulation uses spectral methods to solve Euler's equation in a cylindrical geometry. - Measurements on wave propagation and the ion beam instability in an unmagnetized plasma with an ion beam with a finite diameter. - Development of software for the automated acquisition of data. This program can control an experiment as well as make measurements. It also include a graphics part. (author) 66 ills., 47 refs

47

Experimental Investigation of Shock Wave Surfing  

CERN Document Server

Shock wave surfing is investigated experimentally in GALCIT's Mach 4.0 Ludwieg Tube. Shock wave surfing occurs when a secondary free-body follows the bow shock formed by a primary free-body; an example of shock wave surfing occurs during meteorite breakup. The free-bodies in the current investigation are nylon spheres. During each run in the Ludwieg tube a high speed camera is used to capture a series of schlieren images; edge tracking software is used to measure the position of each sphere. Velocity and acceleration are had from processing the position data. The radius ratio and initial orientation of the two spheres are varied in the test matrix. The variation of sphere radius ratio and initial angle between the centers of gravity are shown to have a significant effect on the dynamics of the system.

Parziale, N J; Hornung, H G; Shepherd, J E

2010-01-01

48

Preparation of bentonites for laboratory investigations  

International Nuclear Information System (INIS)

A project study on behalf of Nagra for high radioactive waste disposal in deep geological formations as well as literature studies have shown that bentonite could be a suitable filling and sealing material. The Institute for Foundation and Soil Mechanics of the Swiss Institute of Technology has been given a contract by Nagra to investigate different bentonites. The investigations concentrate on the Na-bentonite MX-80 from Wyoming, which is foreseen by the Swedes, and on the geographically more favorable Ca-bentonite Montigel from Bavaria. Montigel powder and granulate, which show certain manufacturing advantages, were investigated. The quality of the bentonites was examined especially to ascertain whether the bentonites were homogeneous with respect to composition and properties. Montmorillonite, carbonate, oxidizing substances and exchangeable ions were quality content criteria for bentonite. The investigations showed that these bentonites are typical Na- and Ca-bentonites. A representative sample of 500 kg weight (250 kg for Montigel K) was largely homogeneous. The samples were analysed by x-rays and thermoanalysis. Additionally grain size, carbonate content, methylene blue value, yield point, exchange capacity and exchangeable ions were determined. 5 refs., 2 figs., 2 tabs

49

Experimental investigation of hydrogen cryogenic distillation  

International Nuclear Information System (INIS)

Research conducted in the last fifty years has shown that one of the most efficient techniques of tritium removing from the heavy water used as moderator and coolant in CANDU reactors (as those operated at Cernavoda NPP in Romania) is the hydrogen cryogenic distillation. Designing and implementing the concept of cryogenic distillation columns require experiments to be conducted as well as computer simulations. Particularly, computer simulations are of great importance in designing and evaluating the performances of a column or a series of columns. Experimental data obtained from laboratory work will be used as input for computer simulations run at larger scale (within the Pilot Plant for tritium and deuterium separations) in order to increase the confidence in the simulated results. The studies carried out so far were focused on the following: - Quantitative analyses of important parameters such as the number of theoretical plates, inlet areas, reflux flow, flow-rates extraction, working pressure, etc; - Column in-series connecting to fulfil the separation requirements. Bench-scale experiments were carried out to assess the performances of contact elements with continuous packing prepared in our institute. (authors)

50

Experimental investigations of MFCI in Russia  

International Nuclear Information System (INIS)

This report contains a review of the experimental investigations of MFCI which are carried out as applied to the safety problems of LMFBR, mainly in IPPE. Until the present time these investigations have been performed in out of pile conditions, using different substances for molten fuel simulation. A brief description of the experimental installations and results obtained in the course of experimental program realization is given. In particular the results are presented on the study of MFCI phenomenology with regards to the influence on the interaction energy release of such factors as: type of molten fuel-coolant contact, temperature conditions, ratio of interacted masses, scale factor. Simulation experiments have been effectuated using the following pairs of interaction media: low-melting metals (Lead, Tin, Bismuth, Aluminium)/water; molten Titan and Stainless steel/water; molten Titan and Stainless steel/sodium, eutectic alloy potassium-sodium; alumina/sodium; thermite mixture (Zr + Fe2O3)/water, sodium. The experiments were carried out mainly with the melts masses below 1 kg, except for some series of the experiments on molten Lead-water interaction, where the melt masses as big as 40 kg were used. Initial temperatures of low-melting metals have not exceeded 800 deg. C, while for the Stainless steel, Titan melts and alumina they were equal to 2200 deg. and 2500 deg. C respectively. The temperature of the melt, obtained by combustion of the thermite mixture Zr + Fe2O3, was about 3000 deg. C. The first part of the MFCI investigation program has been completed for the present time. A set of the data on the dynamical characteristics of interactions (time delays, amplitudes and shape of interaction pressure pulses, duration of interaction stage) and conversion coefficients of melt thermal energy into mechanical one was obtained. Analysis of these results has shown an essentially milder interaction energetics in the case of alkali metals coolants as compared with water. Some review is given on the further program of the MFCI study. (author)

51

Experimental investigation of Reykjavik city footbridge  

DEFF Research Database (Denmark)

This study describes experimental investigation of a 160 m long footbridge in Reykjavik. The bridge is a continuous post tensioned concrete beam spanning eight spans, the longest being 27.1 m. In plan, the structure has eye-catching spiral shape. Modal testing of the structure was conducted to identify its dynamic properties. As many as seven modes of vibration were identified in the low-frequency region up to 5 Hz. After this a series of controlled tests involving up to 38 test subjects were performed. These were designed to test vibration performance of the footbridge under various loading scenarios such as: single person either walking or jumping, group of people walking, jogging or jumping and stream of pedestrians. The severity of vibration responses of the bridge for different scenarios was then evaluated against vibration serviceability criteria defined in a guideline. It was found that the vibration performance of the bridge is quite satisfactory for wide range of loading conditions. ©2010 Society forExperimental Mechanics Inc.

Ingólfsson, Einar Thór

2011-01-01

52

Experimental investigation of passive pool mixing  

International Nuclear Information System (INIS)

After the initial blow-down phase of a hypothetical design basis accident or severe accident in the General Electric Simplified Boiling Water Reactor (SBWR), heat is added to the suppression pool by gas-vapor flow through the isolation condenser (IC) and passive containment cooler (PCC) vent lines. The exit of the vent lines is fairly shallow (on the order of 0.75 meters) in order to enhance IC/PCC operation. The surface temperature of a pool increases when heat is injected. The magnitude of increase depends on the amount of the pool involved in heat absorption and thermal gradients in the absorbing region. Thermal stratification occurs because a rising plume carries the energy of the vented gas-vapor to the pool surface and, as a result, only the region of the pool above the injection point is involved in heat absorption. This experimental investigation demonstrated the feasibility of using the IC/PCC vent flow to drive pool mixing. A passive mixer was designed and constructed on the basis of buoyancy and momentum utilization. The mixer was sized to represent one in a system of several mixers which could be implemented in the SBWR. The experimental results show that the potential exists to involve a significant amount of the suppression pool in heat absorption using a passive mixer

53

Experimental and computational investigations of binary solidification  

Science.gov (United States)

The topic of this dissertation is the solidification of a binary melt. The investigation is separated into three portions: An experimental investigation on the NHsb4Cl-Hsb2O system; the development of a Cellular Automata code; and the development of a pair of coupled partial differential equations governing the evolution of an array of dendrites. Any necessary concepts are reviewed in the introduction. The experimental investigation focuses on the morphological transition from "slow" dendrites to "fast" dendrites. It is shown how the very complicated structures occurring during the transition actually have a simple explanation. The "slow-to-fast" transition has been previously investigated in the literature, and the relationships obtained in those studies can not account for the data collected in the present study. When "slow" dendrites are cooled into the "fast" regime, a curious stagnation of growth has also been observed. Additionally, two mechanisms are proposed as possible contributions to the order-of-magnitude jump in speed at the slow-to-fast transition. One mechanism is that of a "herringbone structure", and the other is that of a vortical fluid flow occurring at the tip of the dendrite. A relationship is also found which further indicates the importance of fluid flow. The cellular automata model developed in this dissertation has proven to be a valuable tool in gaining insight into the solidification process. The simulated growth is governed predominantly by the diffusion of solute and the Gibbs-Thomson effect. Solutal diffusion, is accurately treated, diffusing differently through liquid than through solid. The interface curvature is approximated using a template method, into which crystalline anisotropy has also been introduced. Several features were added to explore interface kinetics, solute partitioning, and fluid flow due to shrinkage. Simulations on a 100 × 100 system typically required less than a minute on a workstation, and only qualitative agreement with the experiments was sought. The partial differential equations for the evolution of a growing array of dendrites are derived taking into account only diffusion. It is explicitly shown how the non-conservative equations conserve all of the material in the solidifying system.

Kremeyer, Kevin P.

54

Mars Science Laboratory Mission and Science Investigation  

Science.gov (United States)

Scheduled to land in August of 2012, the Mars Science Laboratory (MSL) Mission was initiated to explore the habitability of Mars. This includes both modern environments as well as ancient environments recorded by the stratigraphic rock record preserved at the Gale crater landing site. The Curiosity rover has a designed lifetime of at least one Mars year (˜23 months), and drive capability of at least 20 km. Curiosity's science payload was specifically assembled to assess habitability and includes a gas chromatograph-mass spectrometer and gas analyzer that will search for organic carbon in rocks, regolith fines, and the atmosphere (SAM instrument); an x-ray diffractometer that will determine mineralogical diversity (CheMin instrument); focusable cameras that can image landscapes and rock/regolith textures in natural color (MAHLI, MARDI, and Mastcam instruments); an alpha-particle x-ray spectrometer for in situ determination of rock and soil chemistry (APXS instrument); a laser-induced breakdown spectrometer to remotely sense the chemical composition of rocks and minerals (ChemCam instrument); an active neutron spectrometer designed to search for water in rocks/regolith (DAN instrument); a weather station to measure modern-day environmental variables (REMS instrument); and a sensor designed for continuous monitoring of background solar and cosmic radiation (RAD instrument). The various payload elements will work together to detect and study potential sampling targets with remote and in situ measurements; to acquire samples of rock, soil, and atmosphere and analyze them in onboard analytical instruments; and to observe the environment around the rover. The 155-km diameter Gale crater was chosen as Curiosity's field site based on several attributes: an interior mountain of ancient flat-lying strata extending almost 5 km above the elevation of the landing site; the lower few hundred meters of the mountain show a progression with relative age from clay-bearing to sulfate-bearing strata, separated by an unconformity from overlying likely anhydrous strata; the landing ellipse is characterized by a mixture of alluvial fan and high thermal inertia/high albedo stratified deposits; and a number of stratigraphically/geomorphically distinct fluvial features. Samples of the crater wall and rim rock, and more recent to currently active surface materials also may be studied. Gale has a well-defined regional context and strong evidence for a progression through multiple potentially habitable environments. These environments are represented by a stratigraphic record of extraordinary extent, and insure preservation of a rich record of the environmental history of early Mars. The interior mountain of Gale Crater has been informally designated at Mount Sharp, in honor of the pioneering planetary scientist Robert Sharp. The major subsystems of the MSL Project consist of a single rover (with science payload), a Multi-Mission Radioisotope Thermoelectric Generator, an Earth-Mars cruise stage, an entry, descent, and landing system, a launch vehicle, and the mission operations and ground data systems. The primary communication path for downlink is relay through the Mars Reconnaissance Orbiter. The primary path for uplink to the rover is Direct-from-Earth. The secondary paths for downlink are Direct-to-Earth and relay through the Mars Odyssey orbiter. Curiosity is a scaled version of the 6-wheel drive, 4-wheel steering, rocker bogie system from the Mars Exploration Rovers (MER) Spirit and Opportunity and the Mars Pathfinder Sojourner. Like Spirit and Opportunity, Curiosity offers three primary modes of navigation: blind-drive, visual odometry, and visual odometry with hazard avoidance. Creation of terrain maps based on HiRISE (High Resolution Imaging Science Experiment) and other remote sensing data were used to conduct simulated driving with Curiosity in these various modes, and allowed selection of the Gale crater landing site which requires climbing the base of a mountain to achieve its primary science goals. The Sample Acquisition, Processing, a

Grotzinger, John P.; Crisp, Joy; Vasavada, Ashwin R.; Anderson, Robert C.; Baker, Charles J.; Barry, Robert; Blake, David F.; Conrad, Pamela; Edgett, Kenneth S.; Ferdowski, Bobak; Gellert, Ralf; Gilbert, John B.; Golombek, Matt; Gómez-Elvira, Javier; Hassler, Donald M.; Jandura, Louise; Litvak, Maxim; Mahaffy, Paul; Maki, Justin; Meyer, Michael; Malin, Michael C.; Mitrofanov, Igor; Simmonds, John J.; Vaniman, David; Welch, Richard V.; Wiens, Roger C.

2012-09-01

55

Experimental investigation on lithium borohydride hydrolysis  

Energy Technology Data Exchange (ETDEWEB)

Lithium borohydride, one of the highest energy density chemical energy carriers, is considered as an attractive potential hydrogen storage material due to its high gravimetric hydrogen density (19.6%). Belonging to borohydride compounds, it presents a real issue to overcome aims fixed by the U.S. Department of Energy in the field of energy, and so crystallizes currently attention and effort to use this material for large scale civil and military applications. However, due to its important hygroscopicity, lithium borohydride is a hazardous material which requires specific handling conditions for industrial aspects. In order to understand much more the reaction mechanism involved between LiBH{sub 4} and the water vapor which leads to the native material dehydrogenation, several experimental techniques such as X-ray Photoelectrons Spectroscopy (XPS), Raman spectroscopy, X-Ray Diffraction (XRD) or thermal analysis (TGA/DTA) were investigated. Indeed, depending on water stoichiometric coefficient, several reactions are suggested in literature but the lithium borohydride hydrolysis way reaction scheme is still uncertain. Investigations exhibited interesting results and, highlighted the formation of lithium metaborate dihydrate LiBO{sub 2},2H{sub 2}O as hydrolysis product via such a solid-gas reaction. (author)

Goudon, J.P. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 5209 CNRS, Universite de Bourgogne, 9 avenue Alain Savary, BP 47870, 21078 Dijon Cedex (France); SNPE Materiaux Energetiques, Centre de Recherches du Bouchet, Laboratoire BCFB, 9 rue Lavoisier, 91710 Vert-le-Petit (France); Bernard, F. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 5209 CNRS, Universite de Bourgogne, 9 avenue Alain Savary, BP 47870, 21078 Dijon Cedex (France); Renouard, J.; Yvart, P. [SNPE Materiaux Energetiques, Centre de Recherches du Bouchet, Laboratoire BCFB, 9 rue Lavoisier, 91710 Vert-le-Petit (France)

2010-10-15

56

Investigation of an Experimental Supersonic Axial-Flow Compressor  

Science.gov (United States)

An investigation is in progress at the Langley Laboratory of the NACA to explore the possibilities of axial-flow compressors operating with supersonic velocities relative to the blade rows. The first phase of this investigation, a study of supersonic diffusers, has been reported. The second phase, an analysis of supersonic compressors, has also been reported. Preliminary calculations have shown that very high pressure ratios across a stage, together with somewhat increased mass flows, are possible with compressors which decelerate air through the speed of sound in their rotor blading. These performance characteristics are desirable in compressors for aircraft jet propulsion units, gas turbines, or superchargers. The third phase, presented here, is a preliminary experimental investigation of a supersonic compressor designed to produce a high pressure ratio in a single stage.

Erwin, John R.; Wright, Linwood C.; Kantrowitz, Arthur

1947-01-01

57

Experimental investigation of creep behavior of reactor vessel lower head  

Energy Technology Data Exchange (ETDEWEB)

The objective of the USNRC supported Lower Head Failure (LHF) Experiment Program at Sandia National Laboratories is to experimentally investigate and characterize the failure of the reactor pressure vessel (RPV) lower head due to the thermal and pressure loads of a severe accident. The experimental program is complemented by a modeling program focused on the development of a constitutive formulation for use in standard finite element structure mechanics codes. The problem is of importance because: lower head failure defines the initial conditions of all ex-vessel events; the inability of state-of-the-art models to simulate the result of the TMI-II accident (Stickler, et al. 1993); and TMI-II results suggest the possibility of in-vessel cooling, and creep deformation may be a precursor to water ingression leading to in-vessel cooling.

Chu, T.Y.; Pilch, M.; Bentz, J.H. [Sandia National Labs., Albuquerque, NM (United States); Behbahani, A. [NRC, Washington, DC (United States)

1998-03-01

58

Experimental investigation of wingtip aerodynamic loading  

Science.gov (United States)

An experimental investigation was performed to obtain the aerodynamic loading of a series of wingtips. The wingtips varied in taper ratio (1.0, 0.6, and 0.3) and in sweep angle (0, 20, 30, 35, and 45 deg). The wingtips were tested separately (wingtip only configuration) and while mounted on a semi-span wing. The quarter-chord sweep angle of the wing was varied from 30 deg forward sweep, to unswept, to 30 deg. aft sweep. Wingtip loading was obtained from a six component strainguage balance mounted in the wingtip. The effect of wing sweep and wingtip taper and wingtip sweep on the wingtip lift curve slope, drag polar, and pitching moment behavior is discussed. The obtained wingtip data was used to define blade tip platforms, suitable for use in the Free-Tip Rotor configuration. The Free-Tip Rotor has blade tips, which are allowed to weathervane into the blade tip's relative wind. A passive control moment is applied to the blade tip's pitch axis so as to cause blade tip motion around a prescribed null point providing a finite blade tip lift.

Van Aken, Johannes M.

1990-01-01

59

Propane hydrate nucleation: Experimental investigation and correlation  

DEFF Research Database (Denmark)

In this work the nucleation kinetics of propane gas hydrate has been investigated experimentally using a stirred batch reactor. The experiments have been performed isothermally recording the pressure as a function of time. Experiments were conducted at different stirring rates, but in the same supersaturation region. The experiments showed that the gas dissolution rate rather than the induction time of propane hydrate is influenced by a change in agitation. This was especially valid at high stirring rates when the water surface was severely disturbed.Addition of polyvinylpyrrolidone (PVP) to the aqueous phase was found to reduce the gas dissolution rate slightly. However the induction times were prolonged quite substantially upon addition of PVP.The induction time data were correlated using a newly developed induction time model based on crystallization theory also capable of taking into account the presence of additives. In most cases reasonable agreement between the data and the model could be obtained. Theresults revealed that especially the effective surface energy between propane hydrate and water is likely to change when the stirring rate varies from very high to low. The prolongation of induction times according to the model is likely to be due to a change in the nuclei-substrate contact angle.

Jensen, Lars; Thomsen, Kaj

2008-01-01

60

Laboratory Investigations into Micromechanical Mechanisms Controlling Earthquake Nucleation  

Science.gov (United States)

Improving our understanding of factors controlling spontaneous shear rupture nucleation on a frictional fault would help better define the important physical processes contributing to earthquake rupture and faulting. Our current laboratory investigations quantify the local stress states on a laboratory fault, which control the transition of sliding from stable (quasi-static) to unstable (dynamic), commonly referred to as earthquake nucleation. A fault is experimentally modeled using two Poly(methyl methacrylate) samples in a direct shear configuration. During nucleation, we observed sudden, elastodynamic stress changes using an array of 16 acoustic emission (AE) sensors. Measurements of absolute displacement from these sensors allowed us to characterize general source mechanics using moment tensor inversion. This technique is widely used in seismology and we observe double-couple (DC) focal mechanisms; a source commonly used to characterize in situ earthquakes. During nucleation, we sometimes observe swarms of smaller, ';foreshock' earthquakes (Mw ~ -7), localized in time and space, prior to the incipient mainshock (Mw ~ -3.25). In general, the local perturbations in the stress field induced by the stress drop (??) from a single foreshock was insufficient to cause the subsequent foreshock at the spatial distances recorded experimentally. This implied that the underlying process driving the foreshock sequence (and eventual mainshock) was aseismic slip over the nucleation zone recorded using non-contact sensors. Spatio-temporal distributions of the foreshocks and the near-fault aseismic motions were shown to be directly related to: i) the rate at which the average bulk stress accumulates across the fault (d?f /dt) and ii) the heterogeneity of normal stress caused by the irregular distribution of asperities, respectively. (A) Locations of the foreshocks (FS1-FS9) determined using p-wave travel times from multiple AE sensors. The locations were superimposed on interfacial pressure measurements obtained using pressure sensitive film (high normal stresses appear as red). (B) Enhanced view of the location of FS6 on the pressure sensitive film. (C) Results of moment tensor inversion (red) fitting the experimental data (black) measured by five AE sensors (PZ7-PZ12) for FS6. The double-couple source was representative of a Mw = -7.0 earthquake.

Selvadurai, P. A.; Glaser, S. D.; Kiwan, R. H.

2013-12-01

 
 
 
 
61

Numerical and Experimental Investigation on Root Anchorage  

Science.gov (United States)

In more recent times, the roles played by vegetation in some specific geotechnical processes have been recognized. Vegetation may affect slope stability in many ways. The stability of slopes is governed by the load, which is the driving force that causes failure, and the resistance, which is the strength of the soil-root system. The weight of trees growing on a slope adds to the load but the roots of trees serve as a soil reinforcement and increase the resistance. In order to ensure that the weight of the trees on the slope help to enhance its stability it is required that they are planted down-slope of the neutral point. Maximum contribution is produced if the trees are located at the slope toe. Considering a typical slip circle, at this location the direction of shear force acting on the trees may be considered as close-to-vertical for the purpose of analysis. In this study, 3D numerical simulations of root anchorage have been performed to study the mechanism and the factors influencing the pull out capacity of tree roots. The investigation was performed using ABACUS finite element program. Field pull-out tests were also carried out on Melastoma malabathricum which been shown to be very suitable to be grown on slope, and the results are compared with numerical simulations. Parametric studies were also done to study the effects of factors such as root pattern, angle of inclination as well as soil properties. The results show that the 3D finite element analyses are able to approximately simulate the experimental tests. The results of the field tests, simulations and the parametric studies will be presented and discussed in more details in this paper.

Ali, F.; Osman, N.; Hashim, R.; Khalilnejad, A.

2012-04-01

62

An Investigative, Cooperative Learning Approach to the General Microbiology Laboratory  

Science.gov (United States)

Investigative- and cooperative-based learning strategies have been used effectively in a variety of classrooms to enhance student learning and engagement. In the General Microbiology laboratory for juniors and seniors at James Madison University, these strategies were combined to make a semester-long, investigative, cooperative learning experience…

Seifert, Kyle; Fenster, Amy; Dilts, Judith A.; Temple, Louise

2009-01-01

63

Experimental and Numerical investigations into AKR generation processes  

Science.gov (United States)

Energetic electron streams descending through the auroral magnetosphere are subject to magnetic compression, increasing their gyrational energy which in turn relaxes through cyclotron maser emission in the kilometer band, the Auroral Kilometric Radiation (AKR). A scaled experimental and numerical program has been undertaken to demonstrate the mechanism of this process at microwave frequencies in the laboratory. Recent progress has included the introduction of a low temperature, low density background plasma into the experiment to replicate the residual low energy particles in the auroral magnetosphere and the investigation of the response of the instability to the cyclotron detuning in 3D PiC codes. These tests are important to determine the potential absorption of the radiation at the upper hybrid resonance.

Ronald, Kevin; Speirs, David; Gillespie, Karen; McConville, Sandra; Phelps, Alan; Bingham, Robert; Cross, Adrian; Robertson, Craig; Whyte, Colin; He, Wenlong; Cairns, Alan; Vorgul, Irena; Kellett, Barry

2010-11-01

64

Role of vegetation on erosion processes: experimental investigation  

Science.gov (United States)

Investigations on soil-system ecology are ever more oriented toward quantitative information based on the study of the linkages between physical processes and ecological response in rivers. As it is known, in presence of vegetation, the hydrodynamics characteristics of flow are principally determined by the mutual interrelation between the flow velocity field and the hydraulic behavior (completely submerged or emergent) of the vegetation elements. Much effort has been made toward identifying the theoretical law to interpret the vertical profile of flow longitudinal velocity in vegetated channels. Many theoretical and experimental studies in laboratory channels have been carried out and especially the case of submerged flexible vegetation has been examined (Termini, 2012). The effects of vegetation on flow velocity are significant and of crucial importance for stabilizing sediments and reducing erosion. Vegetation has a complex effect on walls roughness and the study of the hydrodynamic conditions of flow is difficult. Although most studies based on the "boundary layer" scheme so that the hydrodynamic conditions inside and above the vegetated layer are considered separately, some authors (Ghisalberti and Nepft, 2002; Carollo et al., 2008) claim that the "mixing layer" scheme is more appropriate to define the velocity profile both inside and outside the vegetated layer. Experimental program has been recently carried out in two laboratory flumes constructed at the laboratory of Dipartimento di Ingegneria Civile, Ambientale, Aerospaziale, dei Materiali - University of Palermo (Italy) with real and flexible vegetation on the bed. In this paper, attention is paid to the influence of vegetation on the erosion processes both on the bed and on the channel banks. The structure of the detailed flow velocity field is analyzed and compared with that obtained in absence of vegetation. Attention is then devoted to the analysis of soil erosion mechanism. Carollo F.G., Ferro V., Termini D. (2008). Flow velocity profile and turbulence characteristics in a vegetated straight flume. International Congress Riverflow 2008- Cesnme - Izmir (Turkey) 3-5 September Ghisalberti, M. & Nepf, H. M. 2002. Mixing layer and coherent structures in vegetated acquatic flows. Journal of Geophysical Reseach 107(2). Termini D. (2012). Experimental investigation on the role of vegetation on sediment transport mechanism: review of recent results - 9th ISE - International Symposium on Ecohydraulics - 2012, ISSN 0945-358X Vienna - CD proceedings-

Termini, Donatella

2014-05-01

65

The seeker experimental system at MIT Lincoln Laboratory  

Science.gov (United States)

The Seeker Experimental System (SES) is the passive range within MIT Lincoln Laboratory's Optical System Test Facility (OSTF). The SES laboratory focuses on the characterization of passive infrared sensors. Capable of projecting static and dynamic scenes in both cryogenic and room temperature environments, SES supports sensors that range from tactical ground based systems through strategic space-based architectures. Optical infrared sensors are a major component of military systems, having been used to acquire, track, and discriminate between potential targets and improve our understanding of the physics and phenomenology of objects. This paper delineates the capabilities of the SES laboratory and describes how they are used to characterize infrared sensors and develop new algorithms and hardware in the support of future sensor technology. The SES Cryogenic Scene Projection System vacuum chamber has recently been upgraded to allow dynamic projection of radiometrically accurate two-color infrared imagery. Additional capabilities include the ability to combine imagery from multiple sources, NIST traceable radiometric calibration, and dynamic scene projection in an ambient environment using a combination of high speed mirrors, point source blackbodies, and resistive array based dynamic infrared scene projectors.

Hayes, Alexander G.; Downs, George; Gabrielson, Anthony; Harrison, David C.; Hines, Eric L.; Jiang, Leaf A.; Richardson, Jonathan M.; Swenson, Jonathan

2006-05-01

66

Experimental Explosive Characterization for Counterterrorist Investigation  

Science.gov (United States)

A THz spectral characterization of different explosives of special interest for the Spanish National Security Forces "Guardia Civil" is presented in this paper. This forensic analysis has been done in the frequency range from 0.060 THz to 3.5 THz using the Teraview TPS Spectra 3000 system in laboratory conditions. With this equipment the refractive index, absorbance and complex permittivity of the explosive samples have been obtained. In this study, some of the most common used explosives (Bullet gunpowder, mine gunpowder, PETN, TNT, RDX) are analysed paying special attention to differences related to the manufacturing process used to elaborate some of them and to the purity of the samples. The different fabrication processes of the explosives lead to the same spectral behaviour and characteristics. At the same time, the inclusion of some additives in the explosive samples does not alter their main electromagnetic properties. The sensitivity limit of the measurement system has been found to be to 10 mg of explosives. These results will be used to design future THz imaging systems that allow to detect and identify them in security and defence applications and/or to complete laboratory studies after a terrorist action.

Etayo, D.; Maestrojuan, I.; Teniente, J.; Ederra, I.; Gonzalo, R.

2013-08-01

67

Experimental investigation of bifurcation induced bandgap reconfiguration  

Science.gov (United States)

By applying an asymmetric on-site restoring force in a 1D chain of oscillators, we demonstrate experimentally that a morphing in the bandgap structure or passive bandgap reconfiguration can be triggered by an increase in environmental excitation amplitude. Recent studies on wave propagation have focused on new capabilities and behaviors resulting from intrinsic nonlinearities. This paper details a bistable experimental design that achieves amplitude dependent filtering through passive bandgap reconfiguration, which is triggered by a bifurcation. The system studied comprises a 1D chain of axially aligned pendulums in dimer unit cells with geometrically nonlinear nearest neighbor coupling where bistability is induced through repulsive magnets. When the bistability is asymmetric, each potential well has a different linear spectra. Though this paper uses mechanically coupled oscillators as an example, the phenomenon itself could be used in any wave propagation media where asymmetric bistability can be implemented.

Bernard, Brian P.; Mazzoleni, Michael J.; Garraud, Nicolas; Arnold, David P.; Mann, Brian P.

2014-08-01

68

Numerical and experimental investigations on cavitation erosion  

International Nuclear Information System (INIS)

A method is proposed to predict cavitation damage from cavitating flow simulations. For this purpose, a numerical process coupling cavitating flow simulations and erosion models was developed and applied to a two-dimensional (2D) hydrofoil tested at TUD (Darmstadt University of Technology, Germany) [1] and to a NACA 65012 tested at LMH-EPFL (Lausanne Polytechnic School) [2]. Cavitation erosion tests (pitting tests) were carried out and a 3D laser profilometry was used to analyze surfaces damaged by cavitation [3]. The method allows evaluating the pit characteristics, and mainly the volume damage rates. The paper describes the developed erosion model, the technique of cavitation damage measurement and presents some comparisons between experimental results and numerical damage predictions. The extent of cavitation erosion was correctly estimated in both hydrofoil geometries. The simulated qualitative influence of flow velocity, sigma value and gas content on cavitation damage agreed well with experimental observations.

69

Numerical and experimental investigations on cavitation erosion  

Science.gov (United States)

A method is proposed to predict cavitation damage from cavitating flow simulations. For this purpose, a numerical process coupling cavitating flow simulations and erosion models was developed and applied to a two-dimensional (2D) hydrofoil tested at TUD (Darmstadt University of Technology, Germany) [1] and to a NACA 65012 tested at LMH-EPFL (Lausanne Polytechnic School) [2]. Cavitation erosion tests (pitting tests) were carried out and a 3D laser profilometry was used to analyze surfaces damaged by cavitation [3]. The method allows evaluating the pit characteristics, and mainly the volume damage rates. The paper describes the developed erosion model, the technique of cavitation damage measurement and presents some comparisons between experimental results and numerical damage predictions. The extent of cavitation erosion was correctly estimated in both hydrofoil geometries. The simulated qualitative influence of flow velocity, sigma value and gas content on cavitation damage agreed well with experimental observations.

Fortes Patella, R.; Archer, A.; Flageul, C.

2012-11-01

70

Experimental hyperfine structure investigation of atomic La  

Energy Technology Data Exchange (ETDEWEB)

Optogalvanic laser spectroscopy has been applied to measure the hyperfine structure of 19 spectral lines of La I in the wavelength regions from 570 to 590 nm and 700 to 825 nm. Experimental hyperfine structure constants A and B of the isotope {sup 139}La have been measured for 16 levels of odd parity. From those values six magnetic dipole and ten electric quadrupole constants have been determined for the first time. Some disagreements with previously obtained values are discussed.

Basar, Guenay [Physics Engineering Department, Faculty of Science and Letters, Technical University of Istanbul, 80626 Maslak, Istanbul (Turkey); Basar, Goenuel [Physics Department, Faculty of Science, Istanbul University, 34459 Vezneciler, Istanbul (Turkey); Er, Alev [Physics Department, Faculty of Science, Istanbul University, 34459 Vezneciler, Istanbul (Turkey); Kroeger, Sophie [Institut fuer Atomare und Analytische Physik, Technische Universitaet Berlin, Hardenbergstr. 36, 10623 Berlin (Germany)

2007-04-15

71

A Vodcasted, Cross-Disciplinary, Behavioral Neuroscience Laboratory Exercise Investigating the Effects of Methamphetamine on Aggression  

Science.gov (United States)

This article describes a laboratory experience utilizing videos to engage students in hypothesis-driven experimentation in behavioral neuroscience. It provides students with an opportunity to investigate the effects of chronic methamphetamine exposure on aggression in adult mice using a resident-intruder paradigm. Instructors and students only…

Shanks, Ryan A.; Southard, E. Megan; Tarnowski, Laura; Bruster, Matthew; Wingate, Stacia W.; Dalman, Nancy; Lloyd, Steven A.

2011-01-01

72

Laboratory Investigation of Space and Planetary Dust Grains  

Science.gov (United States)

Dust in space is ubiquitous and impacts diverse observed phenomena in various ways. Understanding the dominant mechanisms that control dust grain properties and its impact on surrounding environments is basic to improving our understanding observed processes at work in space. There is a substantial body of work on the theory and modeling of dust in space and dusty plasmas. To substantiate and validate theory and models, laboratory investigations and space borne observations have been conducted. Laboratory investigations are largely confined to an assembly of dust grains immersed in a plasma environment. Frequently the behaviors of these complex dusty plasmas in the laboratory have raised more questions than verified theories. Space borne observations have helped us characterize planetary environments. The complex behavior of dust grains in space indicates the need to understand the microphysics of individual grains immersed in a plasma or space environment.

Spann, James

2005-01-01

73

Experimental and theoretical investigations in muon chemistry  

Energy Technology Data Exchange (ETDEWEB)

This thesis deals with theoretical and experimental aspects of muon chemistry. Section 1 deals with the consequences of the light mass of the muon and includes chapters on molecular structure, angular momentum, form of adiabatic wave functions and their analysis in terms of electronic and nuclear natural orbitals. In section 2 the theory involved in muon spin resonance is presented in detail and the theory of internal rotation of an asymmetric top and frame developed. Results of muon spin resonance studies are presented and analysed. (U.K.).

McKenna, D.

1983-01-01

74

Laboratory investigation of dust impacts on antennas in space  

Science.gov (United States)

We are performing calibration measurements in our laboratory using a dust accelerator to understand the mechanisms how dust impact generated plasma clouds couple into electric field antennas on spacecraft. The S/WAVES electric field instruments on board the twin STEREO spacecraft observed short duration (milliseconds), large amplitude (> 15 mV) voltage spikes associated with the impact of high velocity dust particles on the spacecraft [St. Cyr et al., 2009, MeyerVernet et al, 2009a, Zaslavsky et al., 2012]. These sharp spikes have been attributed to plasma clouds generated by the impact ionization of high velocity dust particles. The high count rate has lead to the interpretation that S/WAVES is detecting nanometer sized dust particles (nano-dust) generated in the inner solar system and accelerated to close to solar wind velocities before impacting the spacecraft at 1 AU. The S/WAVES nano-dust interpretation is currently based on an incomplete understanding of the charge generated from relevant materials and the coupling mechanism between the plasma cloud and the electric field instrument. Calibration measurements are performed at the dust accelerator facility at the University of Colorado to investigate the effect of various impact parameters on the signals measured by the electric field instrument. The dust accelerator facility allows experimental control over target materials, size (micron to sub-micron), and velocity (1-60 km/s) of impacting dust particles, geometry of the impact, the ';spacecraft' potential, and the presence or absence of photoelectrons, allowing each coupling factor to be isolated and quantified. As the first step in this effort, we measure the impact charge generation for materials relevant for the STEREO spacecraft.

Drake, K.; Gruen, E.; Malaspina, D.; Sternovsky, Z.

2013-12-01

75

Experimental and theoretical investigation of optogalvanic effects  

Science.gov (United States)

Research on the 594.5 nm optogalvanic effect in the Neon positive column discharge was performed. Absolute measurements of the effect per unit of absorbed laser power were performed for discharge radius-pressure products of 9.1 cm-Torr to 1.0 cm-Torr and for substaining direct currents of 1 to 16 mA. The effect was modeled in this regime by applying perturbation theory to key rate equations. The model predictions are in agreement with the experimental measurements. Associated measurements of absolute metastable densities indicate that the studied regime covers the transition from a discharge sustained primarily by single-step electron impact ionization to a discharge sustained primarily by two-step ionization via the 2p53s metastable levels.

Lawler, J. E.

1982-11-01

76

Biomass granular screw feeding: An experimental investigation  

Energy Technology Data Exchange (ETDEWEB)

Successful feeding is critical to biomass utilization processes, but difficult due to the heterogeneity, physical properties and moisture content of the particles. The objectives of the present study were to find the mechanisms of blockage in screw feeding and to determine the effects of particle mean size (0.5-15 mm), size distribution, shape, moisture content (10-60%), density and compressibility on biomass particle feeding at room temperature. Wood pellets, sawdust, hog fuel and wood shavings were tested in a screw feeder/lock hopper system previously employed to feed sawdust into a pilot-scale circulating fluidized-bed gasifier. Experimental results showed that large particles, wide size distributions, large bulk densities and high moisture contents generally led to larger torque requirements for screw feeding. The ''choke section'' and seal plug play important roles in determining the torque requirements. (author)

Dai, Jianjun; Grace, John R. [Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, BC, V6 T 1Z3 (Canada)

2011-02-15

77

Experimental investigation of a cylindrical implosion geometry  

International Nuclear Information System (INIS)

Preliminary experiments without a magnetic field of a new cylindrical implosion megagauss generator were performed. The main purposes of the investigation were to obtain both the liner velocity and the symmetry of implosion. Using the pin contactor method 4.5 mm/?s liner velocity was measured. Satisfactory symmetry of implosion was observed with an IMACON 790 image converter camera in a special optical arrangement. (Author)

78

Experimental Investigation of Centrifugal Compressor Stabilization Techniques  

Science.gov (United States)

Results from a series of experiments to investigate techniques for extending the stable flow range of a centrifugal compressor are reported. The research was conducted in a high-speed centrifugal compressor at the NASA Glenn Research Center. The stabilizing effect of steadily flowing air-streams injected into the vaneless region of a vane-island diffuser through the shroud surface is described. Parametric variations of injection angle, injection flow rate, number of injectors, injector spacing, and injection versus bleed were investigated for a range of impeller speeds and tip clearances. Both the compressor discharge and an external source were used for the injection air supply. The stabilizing effect of flow obstructions created by tubes that were inserted into the diffuser vaneless space through the shroud was also investigated. Tube immersion into the vaneless space was varied in the flow obstruction experiments. Results from testing done at impeller design speed and tip clearance are presented. Surge margin improved by 1.7 points using injection air that was supplied from within the compressor. Externally supplied injection air was used to return the compressor to stable operation after being throttled into surge. The tubes, which were capped to prevent mass flux, provided 9.3 points of additional surge margin over the baseline surge margin of 11.7 points.

Skoch, Gary J.

2003-01-01

79

Experimental Concepts for Generating Negative Energy in the Laboratory  

Science.gov (United States)

Implementation of faster-than-light (FTL) interstellar travel via traversable wormholes, warp drives, or other spacetime modification schemes generally requires the engineering of spacetime into very specialized local geometries. The analysis of these via Einstein's General Theory of Relativity (GTR) field equations plus the resultant equations of state demonstrate that such geometries require the use of ``exotic'' matter in order to induce the requisite FTL spacetime modification. Exotic matter is generally defined by GTR physics to be matter that possesses (renormalized) negative energy density, and this is a very misunderstood and misapplied term by the non-GTR community. We clear up this misconception by defining what negative energy is, where it can be found in nature, and we also review the experimental concepts that have been proposed to generate negative energy in the laboratory.

Davis, E. W.; Puthoff, H. E.

2006-01-01

80

Simulation and Experimentation in an Astronomy Laboratory, Part II  

Science.gov (United States)

The availability of low-cost, high-performance computing hardware and software has transformed the manner by which astronomical concepts can be re-discovered and explored in a laboratory that accompanies an astronomy course for non-scientist students. We report on a strategy for allowing each student to understand fundamental scientific principles by interactively confronting astronomical and physical phenomena, through direct observation and by computer simulation. Direct observation of physical phenomena, such as Hooke's Law, begins by using a computer and hardware interface as a data-collection and presentation tool. In this way, the student is encouraged to explore the physical conditions of the experiment and re-discover the fundamentals involved. The hardware frees the student from the tedium of manual data collection and presentation, and permits experimental design which utilizes data that would otherwise be too fleeting, too imprecise, or too voluminous. Computer simulation of astronomical phenomena allows the student to travel in time and space, freed from the vagaries of weather, to re-discover such phenomena as the daily and yearly cycles, the reason for the seasons, the saros, and Kepler's Laws. By integrating the knowledge gained by experimentation and simulation, the student can understand both the scientific concepts and the methods by which they are discovered and explored. Further, students are encouraged to place these discoveries in an historical context, by discovering, for example, the night sky as seen by the survivors of the sinking Titanic, or Halley's comet as depicted on the Bayeux tapestry. We report on the continuing development of these laboratory experiments. Futher details and the text for the experiments are available at the following site: http://astro4.ast.vill.edu/ This work is supported by a grant from The Pew Charitable Trusts.

Maloney, F. P.; Maurone, P. A.; Hones, M.

1995-12-01

 
 
 
 
81

Experimental investigations of active air bearings  

DEFF Research Database (Denmark)

Along with traditional oil lubrication, increasing demand for high-speed applications has renewed attention to gas bearings technology. Traditional aerostatic and aerodynamic gas lubrication has been widely used in a variety of applications, ranging from high-speed spindles to micro and meso-scale turbomachinery. The present paper deals with experimental rotordynamic testing of a flexible rotor supported by hybrid aerostaticaerodynamic gas journal bearing equipped with an electronic radial air injection system. From a rotordynamic point of view there are two phenomena that limit the widespread of traditional gas lubrication: 1) Low damping makes operation across critical speed dangerous, as even low level of unbalance can generate large vibration responses. This is especially problematic for gas bearing applications, which often operate in the supercritical region. Moreover, 2) An upper bound to supercritical operation is determined by the appearance of subsynchronous whirl instability. Due to the sudden increase in amplitude with respect to speed, this most often corresponds to the maximal attainable rotational speed of the system. Postponing the onset speed of instability poses therefore one of the greatest challenges in a high-speed gas bearing design. A great deal of research is devoted to attack such issues, where most propose passive designs such as compliant foil bearings, tilting pad and flexure pivot gas bearings. These solutions proved to be effective in improving static and dynamic properties of the bearings, however issues related to the manufacturing and accuracy of predictions has so far limited their applications. Another drawback is that passive bearings offer a low degree of flexibility, meaning that an accurate optimization is necessary for each application. The developed prototype active bearing offers several promising performance enhancements. Synchronous vibrations can be effectively addressed ensuring safe operation across the critical speeds; whirling instability is suppressed; interveningon the software, rather than the hardware can modify the response of the system. Implementing active lubrication adds however a considerable number of parameters and variables. The performance of a good control system lays most importantly on a good choice of control gains, which in general are different depending on the goal of the controller. Optimum tuning of the control loop is addressed experimentally, showing dependency on the supply pressure and, less prominently, the rotational velocity. Copyright © 2012 by ASME.

Santos, Ilmar; Morosi, Stefano

2012-01-01

82

Experimental investigation of offshore wave buoy performance  

DEFF Research Database (Denmark)

The important characteristic of sea waves is their high energy density, which is the highest among renewable energy sources. Having up to 2700 km. of shoreline, Iran has a great potential in construction of offshore wave buoys (hereafter called OWB). In this article a OWB model with the possibility of assembling different buoy configurations is introduced. The system is exposed to regular and irregular waves which are generated using wave maker in a 2D wave tank. Wave energy can be extracted from vertical oscillation of its floating buoy. The device is so designed as to operate in rotational (pitch) mode in addition to vertical (heave) motion. Some experiments are also conducted to demonstrate system performance. Experimental results in different conditions are presented and the effect of different buoy configurations on the system efficiency is studied. Numerical simulations that obtain the hydrodynamic coefficients and dynamic response (the Response Amplitude Operator or simply RAO) of each buoy in waves validate test results that the buoy with highest transfer function obtained in simulations has highest efficiency in power extraction. It is finally shown that the horizontal buoy is the most efficient configuration among other constructed buoys for extracting wave energy. The non-dimensional groups are studied and the output power of a full scale OWB is obtained based on similarity laws.

Chivaee, Hamid Sarlak; Seif, M.S.

2013-01-01

83

Experimental Investigation of Orthoenstatite Single Crystal Rheology  

Science.gov (United States)

The plasticity of enstatite, upper mantle second most abundant mineral, is still poorly constrained, mostly because of its high-temperature (T) transformation into proto- and clino-enstatite at low pressure (P). Mackwell (1991, GRL, 18, 2027) reports a pioneer study of protoenstatite (Pbcn) single-crystal rheology, but the results do not directly apply to the orthorhombic (Pbca) mantle phase. Ohuchi et al. (2011, Contri. Mineral. Petrol , 161, 961) carried out deformation experiments at P=1.3 GPa on oriented orthoenstatite crystals, investigating the activity of [001](100) and [001](010) dislocation slip systems; they report the first rheological laws for orthoenstatite crystals. However, strain and stress were indirectly constrained in their experiments, which questioned whether steady state conditions of deformation were achieved. Also, data reported for [001](100) slip system were obtained after specimens had transformed by twinning into clinoenstatite. We report here new data from deformation experiments carried out at high T and P ranging from 3.5 to 6.2 GPa on natural Fe-bearing enstatite single crystals, using the Deformation-DIA apparatus (D-DIA) that equipped the X17B2 beamline of the NSLS (NY, USA). The applied stress and specimen strain rates were measured in situ by X-ray diffraction and imaging techniques (e.g., Raterron & Merkel, 2009, J. Sync. Rad., 16, 748; Raterron et al., 2013, Rev. Sci. Instr., 84, 043906). Three specimen orientations were tested: i) with the compression direction along [101]c crystallographic direction, which forms a 45° angle with both [100] and [001] axes, to investigate [001](100) slip-system activity; ii) along [011]c direction to investigate [001](010) system activity; iii) and along enstatite [125] axis, to activate both slip systems together. Crystals were deformed two by two, to compare slip system activities, or against enstatite aggregates or orientated olivine crystals of known rheology for comparison. Run products microstructures were investigated by transmission electron microscopy. Despite a significant hardening with P, enstatite [001](100) slip system is found to be the easiest system at mantle P and T. Furthermore, orthoenstatite crystals exhibit a higher sensitivity to stress than olivine crystals, i.e. a higher n exponent in classical power laws. At the low stress level prevailing in the Earth mantle, enstatite crystals are thus harder than olivine crystals.

fraysse, G.; Girard, J.; Holyoke, C. W.; Raterron, P.

2013-12-01

84

Experimental investigations of drilling on CFRP composites  

Science.gov (United States)

This paper outlines the various problems associated with the drilling of CFRP composites. The technique of dimensional analysis is used to investigate the complex correlation between thrust force, cutting speed, feed, hole diameter, point geometry, and material thickness during the drilling of holes in CFRP composites. A new non-dimensional number (t/D), thickness of layered composites to drill diameter, is found to influence the thrust force. Four drill point geometries specifically found effective in drilling of FRPs were tried and among them the eight facet drill point geometry was found to give the best results.

Bhatnagar, Naresh; Naik, N. K.; Ramakrishnan, N.

85

Rhodium carbonyl hydride species. A theoretical and experimental investigation  

Energy Technology Data Exchange (ETDEWEB)

A theoretical investigation (ab initio) and experimental data have been combined in an attempt to characterize the rhodium carbonyl hydride species which has been shown previously in these laboratories and in those of Solymosi to be a long-lived surface species for supported rhodium in the catalytic hydrogenation reactions for CO and CO/sub 2/. The calculations have predicted that a bent rhodium carbonyl hydride species is much more stable than a rhodium formyl species. They have also predicted that the Rh-H stretching frequency should be more than 300 cm/sup -1/ lower than the C-O stretching frequency for the rhodium carbonyl hydride species. This prediction is at odds with assigned Rh-H stretching frequencies for Rh organometallic complexes which place Rh-H and C-O stretching frequencies in the same region of the spectrum (2000-2200 cm/sup -1/). The experimental data are not conclusive on this point. The calculations do satisfactorily rationalize the enhanced dissociation of the C-O bond for the rhodium carbonyl hydride species caused by the presence of the hydride moiety.

McKee, M.L.; Dai, C.H.; Worley, S.D.

1988-03-10

86

Experimental Investigation of the Loss Coefficients in a Linear Cascade  

Science.gov (United States)

This paper reports results of experimental investigations on a linear cascade of axial compressor blades. Experiments were conducted in an open circuit subsonic wind tunnel of Aerodynamics Research Laboratory of the Iran University of Science and Technology. Different Reynolds numbers based on the blade chord length were examined, ranging from 80,000 to 500,000. Flow incidences were changed between -8 to +8 degrees with 2 degrees intervals. Freestream turbulence intensity was changed between 1.25 to 4 percent corresponding to different mesh screens mounted upstream of the test model. All the above flow conditions provided to establish various flow regimes, in terms of fully laminar and transitional flows, around the blades. At a specified range of Reynolds numbers laminar separation bubble/bubbles occurred over the blade solid walls. Surface pressure distributions were measured utilizing a computerized data acquisition system. Fluctuating velocities were also measured at various positions around the separation bubble zone, using hot film anemometry. Surface oil flow visualization was carried out for some selected flow conditions. Experimental results were used to study boundary layer characteristics and to determine variations of loss coefficient with each of Reynolds number, flow incidence and turbulence intensity parameters for the test model.

Taghavi-Zenouz, Reza; Etemadi, Majed; Nabati, Mehdi

2014-06-01

87

Experimental Investigation of Natural Fiber Reinforced Polymers  

Directory of Open Access Journals (Sweden)

Full Text Available The potential usage of virgin Low density polyethelyne (LDPE reinforced with different concentrations (2%, 5% and 6% by weight of treated rice straw with different lengths (2 mm, 4 mm and 6 mm is investigated to produce high value products that have technical and environmental demand. The two treatment methods used for rice straw are alkali and acidic treatments of rice straw. The removal of impurities and waxy substances from fiber surface avoid creation of rougher topography after treatment and improves the quality of fiber, also content of hemi cellulose and lignin decrease so increase effectiveness of fiber due to dispersing of fiber in matrix. The reinforcing material is embedded in the matrix material to enhance tensile and flexural behaviors of the synthesized composite. The result of investigating these two mechanical properties, using statistical analysis & design of experiments, showed an enhancement in the mechaniccal properties of the virgin polymer composite compared to the virgin polymer. The flexural stress of the composite increased three times the virgin flexural stress, while the tensile stress increased eight times the original tensile stress.

Salah M. Elhaggar

2012-02-01

88

Experimental and Theoretical Investigations of Wet Flue Gas Desulphurisation  

DEFF Research Database (Denmark)

This thesis describes experimental and theoretical investigations of wet flue gas desulphurisa-tion (FGD). A review of the current knowledge of the various rate determining steps in wet FGD plants is presented. The experimental work covers laboratory studies as well as pilot- and full-scale experiments. In the theoretical part of the work, the laboratory and pilot plant observations are investigated using mathematical modelling.The mechanism underlying the rate of dissolution of finely grinded limestone particles was examined in a laboratory batch apparatus using acid titration. Three Danish limestones of dif-ferent origin were tested. A transient, mass transport controlled, mathematical model was de-veloped to describe the dissolution process. Model predictions were found to be qualitatively in good agreement with experimental data. Deviations between measurements and simulations were attributed primarily to the particle size distribution (PSD) measurements of the limestone particles, which were used as model inputs. The measured PSD was probably not representa-tive of a given limestone sample because of agglomeration phenomena taking place in the dis-perser, preventing a stable and accurate measurement. Other factors, such as convective mass transfer, porosity and porosity changes, and perhaps surface reaction, may also influence the rate of dissolution. However, those effects could not, due to the uncertainty of the PSD, be confirmed. Empirical correlations for the dimensionless mass transfer coefficients in a pilot plant (falling- film column) were determined. The correlations are valid at gas phase Reynolds numbers from 7500 to 18,300 and liquid phase Reynolds numbers from 4000 to 12,000, conditions of industrial relevance. The presence of inert particles in the liquid phase was found to decrease the rate of gas phase mass transport with up to 15 %, though the effect could not be correlated.A detailed model for a wet FGD pilot plant, based on the falling film principle, was devel-oped. All important rate determining steps, absorption of SO2, oxidation of HSO3-, dissolution of limestone, and crystallisation of gypsum were included. Model predictions were compared to experimental data such as gas phase concentration profiles of SO2, slurry pH-profiles, sol-ids contents of the slurry, liquid phase concentrations, and residual limestone in the gypsum. Simulations were found to match experimental data for the two Danish limestone types (Faxe Bryozo and a chalk, Mikrovit) investigated. Gas phase mass transport was found to be the dominating rate determining step, though the liquid phase mass transport resistance could not be neglected. Simulations and experimental data both showed the same degree of desulphuri-sation and absorber pH profile for the two limestone types using a holding tank pH of 5.5, but the residual limestone in the gypsum was significantly lower for the chalk. Furthermore, simulations showed that between 10 and 30 % of the limestone dissolves in the absorber de-pending on the process conditions. A typical holding tank pH of 5-5.5 (also used in full-scale wet FGD packed towers) was found to be a reasonable compromise between residual lime-stone in the gypsum and the degree of desulphurisation. Simulations were only slightly sensi-tive to the temperature in the interval 313 - 333 K, pertinent for full-scale wet FGD packed towers. The possibility of co-firing straw and coal was investigated in a full-scale power plant. No ef-fects on the overall performance of the wet FGD plant were observed, though laboratory ex-periments with fine dust and fly ash from the full-scale experiments showed a decrease in limestone reactivity. However, the test period was only about one week, probably not allowing the FGD plant to reach steady state operation. Pilot-scale experiments were initiated to investigate the possibility of oxidising spray dry scrubber by-products (TASP) to gypsum in wet FGD plants. The investigations showed that it was possible to oxidise the TASP at concentrations of up to 300 g/litre (feed tank basis

Kiil, SØren

1998-01-01

89

Investigation of Appropriate Refractory Material for Laboratory Electritic Resistrance Furnance  

Directory of Open Access Journals (Sweden)

Full Text Available There have been numerous efforts to increase the local content of furnaces; hence the choice of appropriate refractory material for lining of locally manufactured furnaces has remained a major concern. This research work investigates the choice of appropriate local refractory material for the lining of laboratory electric resistance furnace.Electric resistance furnaces are extensively used in the laboratory for heat treatment of metals and alloys. Refractory binders such as silicon carbide were experimented upon for strength and resistance to high temperature.The results obtained showed that Kankara fireclay containing 15% SiC ( 5.70 % linear shrinkage , 46.2% apparent porosity, 1.77gkm³ Bulk density, 18 cycles of spalling tests at 1300°C, 5.253KN/m² of cold strength has appropriate properties for producing grooved bricks for lining of laboratory electric resistance Furnace.

J.B Agboola

2009-07-01

90

Experimental Investigation and Fabrication of Pneumatic Punch  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents the investigation, design and fabrication of blanking of thin sheet (0.1-2 mm of different sheet material. The blank diameter is considered as 10 mm. The study helped to evaluate the influence of tool clearance, burr formation, sheet thickness, punch/die size and blanking layout on the sheet deformation. The punch load variation with tool travel and stress distribution in the sheet has been obtained. The results indicate that a reduction in the tool clearance increases the blanking load and formation of burr increasing or decreasing at different pressure. The objective of this paper is to study the behaviour of punch and formation of burr.

A.K.GUPTA

2013-06-01

91

Experimental investigation of spark discharge energy  

Science.gov (United States)

Minimum ignition energy is one of the important characteristics for electrostatic sensitivity of explosives and determination of the spark discharge energy is necessary for decision making of explosion prevention. In this paper, the real spark discharge energy was determined by the integration of the measured voltage and discharge current in a needle-to-plate configuration. The influence of the charging voltage and polarity, the charging capacitance and the electrode gap on the spark discharge energy was investigated. It is shown that the energy deposited into the discharge system is always smaller than that stored in the charging capacitor, especially at lower voltages that the discharge shows one current pulse and the energy efficiency is less than 30%. The discharge becomes complete at higher voltages when the discharge shows double pulses and the energy efficiency is close to 100%. For given charging capacitance and voltage, the real discharge energy is determined by the discharge mode rather than the electrode gap or the voltage polarity.

Peng, Zulin; Zhang, Yu; Chen, Dongjie; Miao, Jinsong; Ouyang, Jiting

2013-03-01

92

Experimental investigation of corrosion of structural materials  

International Nuclear Information System (INIS)

Conducted was the corrosion test of a recuperative metal-metal heat exchanger made of the stainless austenite 1Kh18M10T steel in a contact with the 1Kh2M steel, with a sodium coolant. A testing unit has operated at maximum temperatures of 600 and 700 deg C for about 3x104 hours. Oxygen content in liquid sodium has been maintained at about (2-5)x103 mas.%. A comparative testing has also been performed of some ferrite-perlite steels (1Kh2MBF, 1Kh2MB, 1KhMT and others) promising for being used in steam generators with a sodium coolant. An effect of chemical composition of austenite steels on dissolution and mass transfer in sodium was studied. The corrosion process of austenite and chromium steels has been investigated in a flow of the sodium-potassium alloy. The specific features of dissolving pure nickel in lithium have been considered as well as kinetics of ?-phase formation in austenite steels upon their corrosion in lithium

93

Experimental investigation of spark discharge energy  

International Nuclear Information System (INIS)

Minimum ignition energy is one of the important characteristics for electrostatic sensitivity of explosives and determination of the spark discharge energy is necessary for decision making of explosion prevention. In this paper, the real spark discharge energy was determined by the integration of the measured voltage and discharge current in a needle-to-plate configuration. The influence of the charging voltage and polarity, the charging capacitance and the electrode gap on the spark discharge energy was investigated. It is shown that the energy deposited into the discharge system is always smaller than that stored in the charging capacitor, especially at lower voltages that the discharge shows one current pulse and the energy efficiency is less than 30%. The discharge becomes complete at higher voltages when the discharge shows double pulses and the energy efficiency is close to 100%. For given charging capacitance and voltage, the real discharge energy is determined by the discharge mode rather than the electrode gap or the voltage polarity.

94

Experimental investigation of the role of ions in aerosol nucleation  

DEFF Research Database (Denmark)

The role of ions in producing aerosols in Earth’s atmosphere is an area of very active research. Atmospheric (Clarke et al. 1998) and experimental (Berndt et al. 2005) observations have shown that the nucleation of aerosol particles can occur under conditions that cannot be explained by classical nucleation theory. Several ideas have been put forward to solve this nucleation problem, e.g. Ion-Induced Nucleation (Raes & Janssens 1985) and Ternary Nucleation (Kulmala et al. 2000). Experimental investigations exploring the role of ions in particle production are scarce, and often at conditions far removed from those relevant for the lower part of the atmosphere (Bricard et al. 1968). Recent experimental work (Svensmark et al. 2007) demonstrated that ions, produced by cosmic rays in the atmosphere, are likely to play an important role in the production of new aerosol particles. The mechanism whereby energetic cosmic rays can promote the production of cloud condensation nuclei at low altitudes constitutes a linkbetween cosmic rays and Earth's climate and there is thus a need to corroborate the results in a different experiment The present results are obtained in the same laboratory, but using a new setup The experiments were conducted in a 50 L cylindrical reaction chamber made of electropolished stainless steel. Aerosols were grown using photochemically produced sulphuric acid and ionization levels were controlled with a Cs-137 gamma-source. An increase in nucleation was observed when the chamber was exposed to the radioactive source. The results were analyzed using a model based on the General Dynamic Equation and the analysis revealed that Ion Induced Nucleation is the most likely mechanism for the observed nucleation increases and thus confirm the previous results.

Enghoff, Martin Andreas BØdker

95

Flood Water Crossing: Laboratory Model Investigations for Water Velocity Reductions  

Directory of Open Access Journals (Sweden)

Full Text Available The occurrence of floods may give a negative impact towards road traffic in terms of difficulties in mobilizing traffic as well as causing damage to the vehicles, which later cause them to be stuck in the traffic and trigger traffic problems. The high velocity of water flows occur when there is no existence of objects capable of diffusing the water velocity on the road surface. The shape, orientation and size of the object to be placed beside the road as a diffuser are important for the effective flow attenuation of water. In order to investigate the water flow, a laboratory experiment was set up and models were constructed to study the flow velocity reduction. The velocity of water before and after passing through the diffuser objects was investigated. This paper focuses on laboratory experiments to determine the flow velocity of the water using sensors before and after passing through two best diffuser objects chosen from a previous flow pattern experiment.

Kasnon N.

2014-01-01

96

Experimental and numerical investigation of the stability of overhanging riverbanks  

Science.gov (United States)

Although different types of riverbank mass failure have been studied by many researchers, many uncertainties remain in predicting cantilever failures, in part because of a lack of detailed observations of this type of bank collapse. In this study, a laboratory study of cantilever failure was carried out using two types of materials to form overhanging banks with three different densities. The laboratory results show that the occurrence of toppling failures is more probable than the simple shear-type mechanism that has been analyzed most frequently by prior researchers. We go on to model these toppling failures numerically. Specifically, a Mohr-Coulomb model, within the framework of SIGMA/W software (ver. 7.17), was used to simulate the stress-strain behavior of the experimental banks. The numerical results for loess materials are in good agreement with the laboratory observations, but the simulations do not replicate experimental failures observed in higher density, more cohesive soils.

Samadi, A.; Amiri-Tokaldany, E.; Davoudi, M. H.; Darby, S. E.

2013-02-01

97

Hydrochemical investigations in Mizunami Underground Research Laboratory project (Phase 1)  

International Nuclear Information System (INIS)

This report discusses about hydrochemical properties before the construction of the underground research laboratory, hydrochemical model about groundwater evolution, and hydrochemical changes during construction based on the results of investigations in Mizunami Underground Research Laboratory Project (Phase I). Chemical compositions of groundwater are Si-Na-Ca-SO4-HCO3 type and Na-Cl type in Akeyo Formation and in Toki Lignite-bearing Formation, and Toki granite, respectively. Groundwater evolves by water-rock interaction in Akeyo Formation and the mixing process in Toki Lignite-bearing Formation and Toki granite. This hydrochemical model enables prediction of groundwater chemistry in the MIU construction site. In Phase II (Construction Phase), changes of Eh and pH, concentration of sulphate ion and inorganic carbon will take place according to the degassing of dissolved gas. (author)

98

Reduction of friction in fluid transport: experimental investigation  

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: English Abstract in spanish La reducción de fricción o de arrastre (DR) mediante el uso de soluciones poliméricas o surfactantes es sin duda alguna la técnica de reducción de fricción para flujos turbulentos en tuberías mas efectiva (es posible obtener reducciones de hasta un factor de 8 en los coeficientes de fricción en segm [...] entos de tuberías rectas). Desde el punto de vista fundamental, el estudio del fenómeno de DR ofrece la oportunidad de comprender mejor flujos turbulentos; desde el punto de vista práctico, la DR puede ser usada con propositos de ahorro en potencia de bombeo. La implementación comercial de estos aditivos se ha llevado a cabo con éxito en el transporte de petróleo, y la investigación necesaria para la implementación de estas soluciones en muchas otras aplicaciones sigue en proceso, p.ej., en sistemas centrales de calefacción y aire acondicionado, sistemas hidrónicos en edificios, desagües, irrigación, procesos industriales, etc. Nuestros esfuerzos se han enfocado en dos áreas principales: (A) investigación experimental sobre la transferencia de momentum y calor para soluciones reductoras de fricción, y (B) la implementación de estas soluciones en sistemas hidrónicos de enfriamiento en edificios con el propósito de ahorrar energía. Este documento pretende dar una noción general de la investigación experimental que llevamos a cabo en nuestro laboratorio de dinámica de fluidos no-Newtonianos, reología, y transferencia de calor en la UCSB. Abstract in english Drag reduction (DR) by the use of polymer and surfactant solutions is by far the most effective drag-reducing technique for turbulent flows (up to 8-fold reduction in friction coefficients is possible on straight pipes). From a fundamental point of view, the study of the DR phenomenon offers an oppo [...] rtunity for a better understanding of turbulence in general; from a practical point of view, DR can be used to save pumping power. Commercial implementation of drag-reducing fluids has proved successful for oil pipeline transportation, and looks promising for many other applications that are still under investigation, e.g. district heating or cooling systems, hydronic systems in buildings, sewers, irrigation, industrial processes, etc. Our efforts have focused on two main areas: (A) experimental research on momentum and heat transfer of turbulent flows of drag-reducing solutions, and (B) implementation of these solutions in hydronic cooling systems in buildings for energy conservation purposes. This paper describes an overview of the typical experimental research that we conduct in our non-Newtonian fluid mechanics, rheology, and heat transfer laboratory at UCSB.

G., Aguilar; K., Gasljevic; E.F., Matthys.

99

Reduction of friction in fluid transport: experimental investigation  

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: English Abstract in spanish La reducción de fricción o de arrastre (DR) mediante el uso de soluciones poliméricas o surfactantes es sin duda alguna la técnica de reducción de fricción para flujos turbulentos en tuberías mas efectiva (es posible obtener reducciones de hasta un factor de 8 en los coeficientes de fricción en segm [...] entos de tuberías rectas). Desde el punto de vista fundamental, el estudio del fenómeno de DR ofrece la oportunidad de comprender mejor flujos turbulentos; desde el punto de vista práctico, la DR puede ser usada con propositos de ahorro en potencia de bombeo. La implementación comercial de estos aditivos se ha llevado a cabo con éxito en el transporte de petróleo, y la investigación necesaria para la implementación de estas soluciones en muchas otras aplicaciones sigue en proceso, p.ej., en sistemas centrales de calefacción y aire acondicionado, sistemas hidrónicos en edificios, desagües, irrigación, procesos industriales, etc. Nuestros esfuerzos se han enfocado en dos áreas principales: (A) investigación experimental sobre la transferencia de momentum y calor para soluciones reductoras de fricción, y (B) la implementación de estas soluciones en sistemas hidrónicos de enfriamiento en edificios con el propósito de ahorrar energía. Este documento pretende dar una noción general de la investigación experimental que llevamos a cabo en nuestro laboratorio de dinámica de fluidos no-Newtonianos, reología, y transferencia de calor en la UCSB. Abstract in english Drag reduction (DR) by the use of polymer and surfactant solutions is by far the most effective drag-reducing technique for turbulent flows (up to 8-fold reduction in friction coefficients is possible on straight pipes). From a fundamental point of view, the study of the DR phenomenon offers an oppo [...] rtunity for a better understanding of turbulence in general; from a practical point of view, DR can be used to save pumping power. Commercial implementation of drag-reducing fluids has proved successful for oil pipeline transportation, and looks promising for many other applications that are still under investigation, e.g. district heating or cooling systems, hydronic systems in buildings, sewers, irrigation, industrial processes, etc. Our efforts have focused on two main areas: (A) experimental research on momentum and heat transfer of turbulent flows of drag-reducing solutions, and (B) implementation of these solutions in hydronic cooling systems in buildings for energy conservation purposes. This paper describes an overview of the typical experimental research that we conduct in our non-Newtonian fluid mechanics, rheology, and heat transfer laboratory at UCSB.

G., Aguilar; K., Gasljevic; E.F., Matthys.

2006-10-01

100

Seismic and geologic investigations of the Sandia Livermore Laboratory site  

International Nuclear Information System (INIS)

This report describes results of a seismic and geologic investigation in the vicinity of Sandia Laboratories property and Sandia's Tritium Building at Livermore, California. The investigation was done to define any seismically capable faults in the immediate area and to obtain necessary information to support estimates of future possible or probable ground motions. The work included a variety of geophysical measurements, trenching, seismologic studies, geologic examination, and evaluation of possible ground surface rupture at the site. Ground motions due to the maximum potential earthquake are estimated, and probability of exceedance for various levels of peak ground acceleration is calculated. Descriptions of the various calculations and investigative techniques used and the data obtained are presented. Information obtained from other sources relevant to subsurface geology and faulting is also given. Correlation and evaluation of the various lines of evidence and conclusions regarding the seismic hazard to the Tritium Building are included

 
 
 
 
101

Experimental study of driven magnetic relaxation in a laboratory plasma  

Science.gov (United States)

The Driven Relaxation Experiment (DRX) has been built at LANL to investigate the possibility of exploiting resonances in the nonlinear force-free equation [1] to optimize magnetic flux amplification and current multiplication for driven-relaxed spheromak-like plasmas, and to explore the application of these ideas to plasma astrophysics problems [2]. It is also our goal to see whether relaxed states with ?> ?1 can be formed and sustained. The experiment uses a planar magnetized coaxial gun (100--180 kA, 1--7 mWb) to generate driven- relaxed plasmas within a cylindrical flux-conserving boundary (0.9 m diameter). Unique features of DRX include high ?gun up to 3?1, and a continuously adjustable boundary elongation. The gun is powered by a 3- stage capacitor bank to form (10 kV, 500 ?F) and sustain (5 kV, 8 mF) the plasma for up to 500 ?s, corresponding to >10 Sweet-Parker times which allows the plasma to reach a quasi-steady-state. The primary diagnostic is a 48- channel 2D magnetic probe array that will map out a poloidal cross-section of the magnetic field configuration at one toroidal position. The full equilibrium magnetic field will be constructed using a combination of the experimental data and a nonlinear force-free equilibrium solver. We will present details of the experimental setup and the first experimental data. Supported by LANL LDRD. [1] Tang & Boozer, PRL 94, 225004 (2005); PRL 98, 175001 (2007) [2] Tang, ApJ 679, 1000 (2008).

Hsu, S. C.; Tang, X. Z.

2008-11-01

102

Diagnostic Protocol Used in Central Disease Investigation Laboratory Dhaka, Bangladesh  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The present study was carried out during a period of four months at Central Disease Investigation Laboratory, Dhaka with the primary aim to measure the frequency of Gumboro in poultry based on sample submission and diagnostic protocol they have been using for poultry disease surveillance. The birds >30 days had a more frequency of Gumboro and the mortality was also comparatively higher in these group (15.66 risk ratio and 4.65 rate ratio). BV 300 strain was affected at a relatively higher rat...

Rashid, M. H.; Atikuzzaman, M.; Rahman, M. A.; Hoque, M. A.; Chowdhury, M. Y. E.

2003-01-01

103

a Laboratory Investigation of Two-Celled Vortex Flows  

Science.gov (United States)

An experimental study of the steady-state kinematics, dynamics, and morphology of two-celled vortex flows has been conducted in the Ward-type tornado vortex chamber (TVC) at Purdue University, with emphasis on exploring the vertical momentum balance in the vortex core and better defining the flow near the external boundaries of the TVC. The TVC was modified for these experiments to more closely compare with numerical models and to allow the implementation of new measurement techniques. Observations of the visualized flow in two-celled vortices and time -averaged static pressure measurements on the axis and at the boundaries of the TVC are reported. Laboratory observations and measurements are compared with results of a numerical model of the TVC flow authored by Rotunno (1984). Laboratory and numerical results are analyzed in terms of the vertical momentum equation. Results show that in the Purdue TVC the flow downstream of the vortex breakdown is everywhere two-celled, with the strongest axial downflow occurring at middle levels. The pressure on the axis in the two-celled vortices increases with height immediately downstream of the breakdown, with the axial pressure gradient tending toward zero farther downstream. The flow-straightening baffle at the downstream terminus of the vortex in the TVC does not critically affect the flow provided the vortex breakdown is well upstream. Analysis of the laboratory findings within the context of the vertical momentum equation shows that the vertical shear stress can play an important role in the axial momentum balance of two-celled vortices by opposing the filling of the vortex core from aloft and so helping to maintain low pressure and high velocities near the surface. The numerical model of Rotunno (1984) is successful in qualitatively replicating several of the flow characteristics in the TVC, including two-celled flow, multiple subsidiary vortices, strongest downflow at middle levels, axial pressure increasing with height, and the role of the vertical shear stress in the axial momentum balance.

Pauley, Randal Lee

104

Experimental and Numerical Investigations into Polymeric Coatings for Blast Protection.  

Science.gov (United States)

Experimental and numerical investigations were conducted to assess the effectiveness of polymeric coatings to enhance the blast protection of steel structures. During the experiments test plates were allowed to deform under close-in blast loading and the ...

K. Ackland, N. St John

2011-01-01

105

Laboratory Investigation of Relaxation Pathways for Vibrationally Excited OH  

Science.gov (United States)

The hydroxyl radical is a key species in the energy budget of the terrestrial atmospheres. In the Earth's upper atmosphere, vibrationally excited OH radicals (v ? 9) are formed by the H + O3 reaction. The non-thermal vibrational energy is either emitted as an infrared (IR) or visible photon, or converted into translational and internal energy via collisions with ambient gases. OH emission was recently reported for the first time in the nightglow of Venus [1]. Model calculations of the Mars airglow have also shown that the predicted intensity of the OH emission is extremely sensitive to the pathway of vibrational relaxation [2]. Accurate rate constant and mechanistic pathway information for the deactivation of the OH(v) states is essential in the modeling of both the atmospheric OH emission and the heating efficiency of the H + O3 reaction, as exemplified in our studies of vibrational relaxation for OH(v = 7, 9) by O, O2, N2, and CO2 [3,4]. We have initiated a research program to investigate the key pathways involved in OH(v) vibrational relaxation and their dependence on the collider species and temperature. In the laboratory experiments, we probe the fraction of collisions that lead to single-quantum relaxation of OH(v = 8) to OH(v = 7) for different atmospheric colliders. We developed a three-laser approach using the following steps: (1) generation of OH(v ? 4) by the O(1D) + H2 reaction following ozone photolysis at 248 nm by an KrF excimer laser in a mixture containing nitrogen and hydrogen; (2) infrared overtone excitation of the OH(v = 4) radicals to v = 7 at 938 nm using a pulsed optical parametric oscillator system triggered when the v = 4 population is near maximum and; (3) detection of the OH(v = 7) population by laser-induced fluorescence using the B - X (0,7) band at 213 nm with a pulsed tunable dye laser timed in order to scan the delay with respect to the IR pump laser. We will present the experimental methodology and measurements on the relaxation of OH(v = 8) to OH(v = 7) by O atoms and CO2. Our measurements to date indicate that different collider gases favor distinct relaxation pathways: the single-quantum cascade branching ratio for collisions with CO2 is approximately 3 times larger than that for collisions with O atoms. We will also discuss the atmospheric implications of our results based on the most current modeling calculations. Research supported by NASA Geospace Science grants NNX08AM47G and NNX12AD09G. [1] Piccioni, G. et al., Astron. Astrophys. 483, L29-L33 (2008). [2] García Muñoz, A. et al., Icarus 176, 75-95 (2005). [3] Thiebaud, J., Kalogerakis, K.S., and Copeland, R.A., Fall AGU Meeting, Abstract SA43A-1752 (2010). [4] Kalogerakis, K.S., G.P. Smith, and R.A. Copeland, J. Geophys. Res. 116, D20307, 2011JD015734 (2011).

Kalogerakis, K. S.; Thiebaud, J.; Matsiev, D.; Copeland, R. A.

2012-04-01

106

Experimental and theoretical investigation of pipe riser clamps  

International Nuclear Information System (INIS)

The experimental investigations--photoelastic as well as strain gage--of two types of pipe riser clamps to be used in nuclear and fossil power plants reveal the presence of large normal and shear stresses in the vicinity of the bend in type A. A rigorous finite element analysis is compared with the experimental result. A set of design recommendations is presented based on the investigation. (Author)

107

Experimental Investigation and Modeling of Integrated Tri-generation Systems  

Science.gov (United States)

Energy demand in the world is increasing with population growth and higher living standards. Today, the need for energy requires a focus on renewable sources without abandoning fossil fuels. Efficient use of energy is one of the most important tasks in modern energy systems to achieve. In addition to the energy need, growing environmental concerns are linked with energy is emerged. Multi-purpose energy generation allows a higher efficiency by generating more outputs with the same input in the same system. Tri-generation systems are expected to provide at least three commodities, such as heating, cooling, desalination, storable fuel production and some other useful outputs, in addition to power generation. In this study, an experimental investigation of gasification is presented and two integrated tri-generation systems are proposed. The first integrated tri-generation system (System 1) utilizes solar energy as input and the outputs are power, fresh water and hot water. It consists of four sub-systems, namely solar power tower system, desalination system, Rankine cycle and organic Rankine cycle (ORC). The second integrated tri-generation system (System 2) utilizes coal and biomass as input and the outputs are power, fuel and hot water. It consists of five sub-systems: gasification plant, Brayton cycle, Rankine cycle, Fischer-Tropsch synthesis plant and an organic Rankine cycle (ORC). Experimental investigation includes coal and biomass gasification, where the experimental results of synthesis gas compositions are utilized in the analysis of the second systems. To maximize efficiency, heat losses from the system should be minimized through a recovery system to make the heat a useful commodity for other systems, such as ORCs which can utilize the low-grade heat. In this respect, ORCs are first analyzed for three different configurations in terms of energy and exergy efficiencies altering working fluids to increase the power output. Among two types of coal and one type biomass tried in the laboratory scale experimental set-up, Tuncbilek-Omerler is found to be superior to Konya-Ilgin coal in terms of the highest amount of hydrogen in the synthesis gas composition. As biomass, wheat straw is gasified, which shows higher exergetic efficiency in comparison to Konya-Ilgin coal. Based on theoretical analysis conducted for the integrated systems, System 2 is found to be more efficient in terms of energy and exergy in comparison with System 1. However, when local needs are taken into account, fresh water can be a desirable useful output where solar irradiation is high. Both systems are compared to conventional and co-generation systems having the same inputs to quantify the improvement in efficiency. System 1 has an energy efficiency of 69% and an exergy efficiency of 58%, whereas System 2 has an energy efficiency of 71% and an exergy efficiency of 73%. When single generation is obtained from the same inputs, it is observed that the energy and exergy efficiencies drop drastically down to 34% and 42% for System 1; 33% and 42% for System 2, respectively.

Cetinkaya, Eda

108

Laboratory investigation of dispensing systems for swormlure-4  

International Nuclear Information System (INIS)

Laboratory investigations of the release of the components of swormlure-4 from open bottles showed that release of dimethyldisulphide was unexpectedly rapid, whereas relative release rates of the other components were in line with their boiling points. Examination of release from sealed polythene sachet dispensers showed relatively rapid release of dimethyldisulphide, release of the carboxylic acids at medium rates and slow release of the other components, including the volatile butyl alcohols. Release rates from the sachets are known to depend upon thickness of the polythene and their surface area, and a system giving release rates for all the components suitable for attraction of screwworm in the field could be designed. This would comprise a thin-walled sachet for all the components except the dimethyldisulphide, and the latter in a commercially-available, thick-walled sachet. 10 figs, 1 tab

109

An adaptable investigative graduate laboratory course for teaching protein purification.  

Science.gov (United States)

This adaptable graduate laboratory course on protein purification offers students the opportunity to explore a wide range of techniques while allowing the instructor the freedom to incorporate their own personal research interests. The course design involves two sequential purification schemes performed in a single semester. The first part comprises the expression and purification of a recombinant GFP-binding protein from E. coli. The student-purified GFP-binding protein is then used in the second part of the course to immunoprecipitate GFP-tagged proteins, and their potential interacting partners, from cell or tissue extracts. As an example, we describe the immunoprecipitation of GFP-tagged proteins from Drosophila melanogaster larval extracts that are homologous to proteins implicated in human diseases, followed by western blotting to examine student experimental outcomes. However, the widespread availability of GFP-fusion proteins in diverse organisms enables researchers to tailor the second part of the course to their specific research programs while maintaining the flexibility to engage students in active learning. Student evaluations indicate a genuine excitement for research and in depth knowledge of both the techniques performed and the theory behind them. © 2014 by The International Union of Biochemistry and Molecular Biology, 42(6):486-494, 2014. PMID:25331587

Carroll, Christopher W; Keller, Lani C

2014-11-12

110

Experimental investigations of thermal interaction between corium and coolants  

Science.gov (United States)

We present a generalized analysis of the experimental results from investigations of thermal interaction in corium simulators (melts of thermite mixtures U + Mo3 and Zr + Fe2O3)-coolant (Na and H2O) systems. We also present the results from experimental assessments of the kinematic characteristics pertinent to the displacement of materials during the thermal interaction process and the coefficients for conversion of the corium thermal energy into mechanical work.

Zagorul'ko, Yu. I.; Zhmurin, V. G.; Volov, A. N.; Kovalev, Yu. P.

2008-03-01

111

Experimental Investigation into Electrical Discharge Machining of Stainless Steel 304  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study presents the experimental investigation of the machining characteristics of austenitic stainless steel 304 through electric discharge machining. The effectiveness of the EDM process with stainless steel is evaluated in terms of the removal rate (MRR), the Tool Wear Rate (TWR) and the surface roughness of the work-piece produced. The experimental work is conducted utilizing Die Sinking electrical discharge machine of AQ55L model. Cylindrical copper electrode having a size of Ø19x37...

Rahman, M. M.; Khan, M. A. R.; Kadirgama, K.; Noor, M. M.; Bakar, R. A.

2011-01-01

112

Investigation into stutter ratio variability between different laboratories.  

Science.gov (United States)

The determination of parameters such as stutter ratio is important to inform a laboratory's forensic DNA profile interpretation strategy. As part of a large data analysis project to implement a continuous model of DNA profile interpretation we analysed stutter ratio data from eight different forensic laboratories for the Promega PowerPlex(®) 21 multiplex. This allowed a comparison of inter laboratory variation. The maximum difference for any one laboratory from the average of the best fit determined by the model was 0.31%. These results indicate that stutter ratios calculated from samples analysed using the same profiling kit are not expected to differ between laboratories, even those using different capillary electrophoresis platforms. A common set of laboratory parameters are able to be generated and used for profile interpretation at all laboratories using the same multiplex and cycle number, potentially reducing the need for individual laboratories to determine stutter ratios. PMID:25082139

Bright, Jo-Anne; Curran, James M

2014-11-01

113

Experimental method for investigating helium effects in irradiated vanadium  

International Nuclear Information System (INIS)

Analyses have been performed which indicate that an effective method for experimentally investigating helium effects in neutron irradiated vanadium base alloys can be developed. The experimental procedure involves only modest modifications to existing procedures currently used for irradiation testing of vanadium-base alloys in the FFTF reactor. Helium is generated in the vanadium alloy by decay of tritium which is either preinjected or generated within the test capsule. Calculations indicate that nearly constant He/dpa ratios of desired magnitude can be attained by proper selection of experimental parameters. The proposed method could have a major impact on the development of vanadium base alloys for fusion reactor applications. 8 refs., 4 figs

114

Experimental method for investigating helium effects in irradiated vanadium  

International Nuclear Information System (INIS)

Analyses have been performed which indicate that an effective method for experimentally investigating helium effects in neutron irradiated vanadium base alloys can be developed. The experimental procedure involves only modest modifications to existing procedures currently used for irradiation testing of vanadium-based alloys in the FFTF reactor. Helium is generated in the vanadium alloy by decay of tritium which is either preinjected or generated within the test capsule. Calculations indicate that nearly constant He/dpa ratios of desired magnitude can be attained by proper selection of experimental parameters. The proposed method could have a major impact on the development of vanadium base alloys for fusion reactor applications. (orig.)

115

An Inquiry-Based Density Laboratory for Teaching Experimental Error  

Science.gov (United States)

An inquiry-based laboratory exercise is described in which introductory chemistry students measure the density of water five times using either a beaker, a graduated cylinder, or a volumetric pipet. Students are also assigned to use one of two analytical balances, one of which is purposefully miscalibrated by 5%. Each group collects data using…

Prilliman, Stephen G.

2012-01-01

116

The experimental platform of magnetic reconnection in laboratory plasma  

International Nuclear Information System (INIS)

A laboratory experiment on the reconnection of magnetic field lines in plasmas has been performed. The plasma is produced by RF discharge, a time-varying magnetic field is applied to two copper plates and the magnetic field exhibits an X-type neutral point in vacuum. The profile of magnetic field is measured by magnetic probe built in 2D moving platform. (author)

117

Numerical and experimental investigations on smart structures with piezoelectric devices  

Energy Technology Data Exchange (ETDEWEB)

The dynamic behavior of a rectangular pin supported plate with piezoelectric patches bonded to the center of the upper and lower surfaces is investigated experimentally and numerically. Frequency response functions are generated by hammer impact as well as by stimulation of the piezoelectric patches, the mode shapes are investigated, and confirmed by holographic interferometry. For the numerical analysis of smart structures with piezoelectric devices a method is proposed that makes only use of conventional finite elements. Eigenfrequencies and mode shapes are determined. Experimental and numerical results are in good agreement. (orig.)

Lammering, R.; Wiesemann, S. [Univ. of the Federal Armed Forces, Hamburg (Germany). Inst. of Mechanics

1998-10-01

118

Investigating the dynamics of Vulcanian explosions using scaled laboratory experiments  

Science.gov (United States)

Laboratory experiments were conducted to investigate the dynamics of Vulcanian eruptions. A reservoir containing a mixture of water and methanol plus solid particles was pressurized and suddenly released via a rapid-release valve into a 2 ft by 2 ft by 4 ft plexiglass tank containing fresh water. Water and methanol created a light interstitial fluid to simulate buoyant volcanic gases in erupted mixtures. The duration of the subsequent experiments was not pre-determined, but instead was limited by the potential energy associated with the pressurized fluid, rather than by the volume of available fluid. Suspending liquid density was varied between 960 and 1000 kg m-3 by changing methanol concentrations from 5 to 20%. Particle size (4 & 45 microns) and concentration (1 to 5 vol%) were varied in order to change particle settling characteristics and control bulk mixture density. Variations in reservoir pressure and vent size allowed exploration of the controlling source parameters, buoyancy flux (Bo) and momentum flux (Mo). The velocity-height relationship of each experiment was documented by high-speed video, permitting classification of the laboratory flows, which ranged from long continuously accelerating jets, to starting plumes, to low-energy thermals, to collapsing fountains generating density currents. Field-documented Vulcanian explosions exhibit this same wide range of behavior (Self et al. 1979, Nature 277; Sparks & Wilson 1982, Geophys. J. R. astr. Soc. 69; Druitt et al. 2002, Geol. Soc. London, 21), demonstrating that flows obtained in the laboratory are relevant to natural systems. A generalized framework of results was defined as follows. Increasing Mo/Bo for small particles (4 microns; settling time > experiment duration) pushes the system from low-energy thermals toward high-energy, continuously accelerating jets; increasing Mo/Bo for large particles (>45 microns; settling time < experiment duration) pushes the system from a low collapsing fountain to a high collapsing fountain; and increasing particle size for collapsing fountains decreases runout distance of gravity currents and increases production of current-generated rising plumes.

Clarke, A. B.; Phillips, J. C.; Chojnicki, K. N.

2005-12-01

119

Experimental econophysics properties and mechanisms of laboratory markets  

CERN Document Server

Experimental Econophysics describes the method of controlled human experiments, which is developed by physicists to study some problems in economics or finance, namely, stylized facts, fluctuation phenomena, herd behavior, contrarian behavior, hedge behavior, cooperation, business cycles, partial information, risk management, and stock prediction. Experimental econophysics together with empirical econophysics are two branches of the field of econophysics. The latter one has been extensively discussed in the existing books, while the former one has been seldom touched. In this book, the author will focus on the branch of experimental econophysics. Empirical econophysics is based on the analysis of data in real markets by using some statistical tools borrowed from traditional statistical physics. Differently, inspired by the role of controlled experiments and system modelling (for computer simulations and/or analytical theory) in developing modern physics, experimental econophysics specially relies on controlle...

Huang, Ji-Ping

2015-01-01

120

Testing Experimental Compounds against Leishmaniasis in Laboratory Animal Model Systems.  

Science.gov (United States)

Pentostam and parasite dose responses have been determined for, and three WRAIR experimental compounds have been tested against visceral and mucocutaneous leishmaniasis. In addition, the conditions for screening compounds against mucocutaneous leishmanias...

J. S. Keithly

1983-01-01

 
 
 
 
121

Experimental investigations of overvoltages in neutral isolated networks  

Energy Technology Data Exchange (ETDEWEB)

For more than a decade, the Nikola Tesla Institute has worked intensively on experimental investigations of transient voltages and currents in neutral isolated networks, usually at 6 kV. The paper presents the results of investigations of overvoltages at the instant of appearance of an earth fault and during its interruption, the earth-fault currents and overvoltages during ferroresonance. Investigations were performed on cable station service networks in hydro- and thermal-power plants, industrial and similar installations in Yugoslavia. On the basis of these investigations, some measures are suggested for improving the reliability of operation of neutral isolated networks. (author)

Vukelja, P.I.; Naumov, R.M.; Vucinic, M.M.; Budisin, P.B. (Electrotechnicki Inst. ' Nikola Tesla' , Belgrade (Yugoslavia))

1993-09-01

122

Investigating Systematic Uncertainty and Experimental Design with Projectile Launchers  

CERN Document Server

The proper choice of a measurement technique that minimizes systematic and random uncertainty is an essential part of experimental physics. These issues are difficult to teach in the introductory laboratory, though: because most experiments involve only a single measurement technique, students are often unable to make a clear distinction between random and systematic uncertainties, or to compare the uncertainties associated with different techniques. In this paper, we describe an experiment suitable for an introductory college level (or advanced high school) course that uses velocity measurements to clearly show students the effects of both random and systematic uncertainties.

Orzel, Chad; Marr, Jonathan

2011-01-01

123

Experimental Investigation of the Integral Constant in Steady Flow Conditions  

Directory of Open Access Journals (Sweden)

Full Text Available An elaborate experimental system was designed and built in the Hydraulics Laboratory of Civil Engineering Department of Dokuz Eylul University, in order to study the velocity distribution by means of an Ultrasonic Velocity Profiler (UVP over rough bed at different flow rates. The UVP which has the advantage of providing instantaneous velocity distribution was also used to measure the bed elevations. The shear velocity, u* and the integral constant, Br were calculated from the mean velocity profiles by applying the Clauser Method and compared with those given in the relevant literature.

?ükrü Mehmet Güney

2010-02-01

124

Software to Enhance Hands-On Laboratory Experimentation  

Science.gov (United States)

This presentation from MATEC explains the transition from using software to getting hands-on experience in a lab. The laboratory setting in technology related courses is an integral part of the learning experience for the student. It takes the theory that is being learned in the lecture and applies that theory. The text books that are used in the lecture include a copy of either Multi Sim or Electronic Workbench. The software gives the student the ability to "build" the circuits that are under study without the hardware that is found in the lab. The students at Grambling State University are not utilizing the software in the beginning level classes. The students must start utilizing the software earlier in the educational career. To accomplish this, the students are starting to complete the lab assignments with software before going to the lab. By doing this, the students will know what to expect before starting lab. This can and hopefully will remove some confusion that the beginner level circuit student has when constructing a circuit. The next step to improving and enhancing the laboratory experience for the student is to add a computer system to each laboratory station. Each system will contain software and hardware that will connect the test instruments to the computer and perform a multitude of analysis functions. The software that has stimulated some interest is MatLab. MatLab includes curriculum for some of the following: digital signal processing, digital image processing, digital filters, signals and systems, speech processing, computer-controlled systems, applied digital signal processing, dynamic modeling of engineering systems, and continuous-time linear systems. In conclusion, the learning invention for this laboratory is to bring together the lecture and lab through the implementation of software and hardware. This was part of the Learning Invention Labs that MATEC held. Visit the MATEC.org homepage for more information.

Flinders, Shirley

2013-01-01

125

Experimental Investigation in Fluid Mechanics – Its Role, Problems and Tasks  

Directory of Open Access Journals (Sweden)

Full Text Available In this contribution, some problems and tasks of experimental fluid mechanics are presented. Paradoxes, basic laws and contemporary investigation approaches are discussed. Experimental results, together with theoretical knowledge and numerical simulations gradually form basis for solution of topical problems. The author of this contribution focuses his investigations into field of compressible fluid flow. Due to this, some results of high-speed aerodynamic research contributing to design and operation of machines, where flow velocities exceed speed of sound, are shown. Moreover, the author intends to show, that fluid mechanics is open field ready to describe complex interactions at fluid flows. Experimental fluid mechanics takes part in formulation and solution of tasks at flow field modelling, at explanation of phenomena taking place in nature and in technical works.

Šafa?ík P.

2013-04-01

126

Experimental investigation of high-current REB interaction with plasma  

International Nuclear Information System (INIS)

Experimental investigation is performed of the interaction of high-current relativistic electron beams with plasma at the Institute of Nuclear Physics in Novosibirsk within the long solenoid thermonuclear reactor program. Physical problems of the beam transport and beam energy deposition in a plasma with electron density up to 1015cm-3 are studied on the INAR and GOL-1 experimental facilities. The collected experimental material together with the present theoretical notions clearly indicate the physical processes accompanying the injection of a high-power electron beam into a plasma. The beam relaxation and plasma heating is governed by collective processes. During the interaction most of the energy is transferred into a small group of high-energy plasma electrons. Relatively high energy transfer efficiency exceeding 30% has been achieved. The interaction can effectively be suppressed by plasma inhomogeneity. All experimental results coincide with the strong Langmuir turbulence concept. (J.U.)

127

Experimental Investigation of Forecasting Methods Based on Universal Measures  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We describe and experimentally investigate a method to construct forecasting algorithms for stationary and ergodic processes based on universal measures (or so-called universal data compressors). Using some geophysical and economical time series as examples, we show that the precision of thus obtained predictions is higher than that of known methods.

Ryabko, Boris; Pristavka, Pavel

2011-01-01

128

Light backscattering in turbid freshwater: a laboratory investigation  

Science.gov (United States)

The relationship between backscattering and inorganic sediment concentration was examined in a controlled laboratory setting. Different concentrations of two sediment sizes (clay/silt and medium sand) of marine clay deposition were added separately in an opaque black tank containing 500 l of distilled water. The experiment used two optical Environmental Characterization Optics-Backscattering sensors to quantify backscattering in m-1 and NTU. Increasing backscatter coefficients (maximum 5.3 m-1) were observed with increasing suspended particulate concentrations up to 272 and 412 mg l-1 for clay/silt and medium sand, respectively. This demonstrates that a greater range of backscattering values can be measured for highly turbid waters than previously measured in situ. Mass-specific backscattering values for clay/silt (0.02 m2 g-1) are on average higher than for medium sand (0.014 m2 g-1). Although the backscattering ratio [b(?)] and refractive index calculated are in accordance with the literature, it is worth noting that the difference in particle size does not exclude differences in matter composition, shape, and other physical factors that contribute to b variation. The results suggest that further investigation of inorganic optical properties affecting particle size as well as matter composition is required in a controlled environment.

Lobo, Felipe L.; Costa, Maycira; Phillips, Stephen; Young, Erika; McGregor, Cory

2014-01-01

129

Laboratory investigations of arcing on W-coated graphite components  

Energy Technology Data Exchange (ETDEWEB)

Results of laboratory experiments of arcing on graphite tiles coated by a W-layer are reported. The samples have been taken from coated tiles manufactured for ASDEX Upgrade (AUG). The motion of the arcs was observed by high-speed cameras. Additionally, sample plates have been exposed to collect macro-particles emitted by the arc. The eroded surfaces of the cathodes were investigated after experiment to characterize surface changes, tracks, and re-deposited particles. On the cathode strongly radiating immobile spots are observed by the cameras acting as sources of numerous macro-particles. At the surface large holes (diameter 17 ?m) are found that perforate the W-layer and extend into the graphite bulk. Subsequent arcs tend to locate at the pre-existing holes. Hence, locally the W-coating is quickly and effectively broken, the W erosion is enhanced as compared to bulk W, and carbon is locally liberated despite the existence of an undamaged W-coating outside the arcing region.

Laux, M., E-mail: michael.laux@ipp.mpg.de [Teilinstitut Greifswald, Wendelsteinstr. 1, D-17491 Greifswald (Germany); Siemroth, P.; Marx, M. [Arc Precision Sources, Coatings and Analysis GmbH, Bahnhofstr. 1, D-15745 Wildau (Germany); Neu, R.; Rohde, V.; Balden, M.; Endstrasser, N. [Max-Planck-Institut für Plasmaphysik, EURATOM Association, Boltzmannstr. 2, D-85748 Garching (Germany)

2013-07-15

130

Laboratory investigations of arcing on W-coated graphite components  

International Nuclear Information System (INIS)

Results of laboratory experiments of arcing on graphite tiles coated by a W-layer are reported. The samples have been taken from coated tiles manufactured for ASDEX Upgrade (AUG). The motion of the arcs was observed by high-speed cameras. Additionally, sample plates have been exposed to collect macro-particles emitted by the arc. The eroded surfaces of the cathodes were investigated after experiment to characterize surface changes, tracks, and re-deposited particles. On the cathode strongly radiating immobile spots are observed by the cameras acting as sources of numerous macro-particles. At the surface large holes (diameter 17 ?m) are found that perforate the W-layer and extend into the graphite bulk. Subsequent arcs tend to locate at the pre-existing holes. Hence, locally the W-coating is quickly and effectively broken, the W erosion is enhanced as compared to bulk W, and carbon is locally liberated despite the existence of an undamaged W-coating outside the arcing region

131

Experimental and numerical investigation on two-phase flow instabilities  

Energy Technology Data Exchange (ETDEWEB)

Two-phase flow instabilities are experimentally and numerically studied within this thesis. In particular, the phenomena called Ledinegg instability, density wave oscillations and pressure drop oscillations are investigated. The most important investigations regarding the occurrence of two-phase flow instabilities are reviewed. An extensive description of the main contributions in the experimental and analytical research is presented. In addition, a critical discussion and recommendations for future investigations are presented. A numerical framework using a hp-adaptive method is developed in order to solve the conservation equations modelling general thermo-hydraulic systems. A natural convection problem is analysed numerically in order to test the numerical solver. Moreover, the description of an adaptive strategy to solve thermo-hydraulic problems is presented. In the second part of this dissertation, a homogeneous model is used to study Ledinegg, density wave and pressure drop oscillations phenomena numerically. The dynamic characteristics of the Ledinegg (flow excursion) phenomenon are analysed through the simulation of several transient examples. In addition, density wave instabilities in boiling and condensing systems are investigated. The effects of several parameters, such as the fluid inertia and compressibility volumes, on the stability limits of Ledinegg and density wave instabilities are studied, showing a strong influence of these parameters. Moreover, the phenomenon called pressure drop oscillations is numerically investigated. A discussion of the physical representation of several models is presented with reference to the obtained numerical results. Finally, the influence of different parameters on these phenomena is analysed. In the last part, an experimental investigation of these phenomena is presented. The designing methodology used for the construction of the experimental facility is described. Several simulations and a non-dimensional similitude analysis are used to support the design, regarding the occurrence of two-phase flow instabilities. Some experimental results are presented in order to validate the current design. A full characterisation of the pressure drop losses in the facility is presented. Both, distributed and local pressure drop losses are investigated and the experimental results are compared with the main correlations used in the literature for the analysis of pressure drop in two-phase flow systems. Finally, pressure drop and density wave oscillations are studied experimentally, with main focus on the interaction of these two oscillation modes. In addition, the influence of compressibility volumes on the stability limits for the density wave phenomenon is analysed.(Author)

Ruspini, Leonardo Carlos

2013-03-01

132

Requirements for Real-Time Laboratory Experimentation over the Internet.  

Science.gov (United States)

A prototype system based on an inverted pendulum is used to study the Quality of Service and discuss requirements of remote-experimentation systems utilized for carrying out control engineering experiments over the Internet. This class of applications involves the transmission over the network of a variety of data types with their own peculiar…

Salzmann, C.; Latchman, H. A.; Gillet, D.; Crisalle, O. D.

133

- El rol de la enfermera en un departamento de Cirugía Experimental (The nurse role in an experimental surgery laboratory  

Directory of Open Access Journals (Sweden)

Full Text Available Los esfuerzos de enfermería en estos últimos años se han centrado en buscar la autonomía y conseguir la independencia de la profesión, tanto en el ejercicio profesional como en el desarrollo científico, lo que ha facilitado su apertura a otros campos del conocimiento, como es la investigativa. La Cirugía experimental constituye una disciplina muy importante de las ciencias biomédicas por las amplias posibilidades que ofrece en el campo de la investigación así como en el adiestramiento de los futuros cirujanos y la enseñanza de pre y postgrado y la dotación de personal en este es vital si se desea mantener esa actividad investigativa que permita resolver problemas de la clínica o susceptibles de la propia investigación, no dejando a un lado la docencia, así como la prestación de servicios a otros departamentos, instituciones, etc., por lo que es imprescindible contar con la presencia de una enfermera, o varias, en dependencia de la cantidad de quirófanos con que cuenta el Dpto. o Laboratorio en cuestión. Tal como en el área clínica, la enfermera en el departamento o laboratorio de cirugía experimental ejerce las tres etapas del perioperatorio, con la ayuda del equipo de trabajo. Estas son: preoperatorio, transoperatorio y postoperatorio. El objetivo de este trabajo es dar a conocer la importancia de la enfermera en el trabajo de un departamento o laboratorio de cirugía experimental. Un centro, departamento o laboratorio de Cirugía experimental que no cuente con una enfermera dentro de su dotación de personal, no podrá realizar un buen trabajo, pues en la atención quirúrgica la enfermera es tan imprescindible como el cirujano, con funciones independientes y a la vez complementarias The nursing efforts during the last few years have been directed specifically in finding autonomy and independence in the profession, not only professionally, but also in the scientific development. It has facilitated its spreading to many fields of knowledge, as it is the case of investigation. Experimental surgery is a very important discipline within the biomedical sciences due to the possibilities it offers in the field of research in training future surgeons and in teaching graduates and non graduates . Personnel working here are quite important to keep the research projects, so as to solve problems related to clinics or associated with investigation. All these aspects should be kept in mind but without letting aside teaching and assistance to other departments, institutions, etc. Having this in mind it is necessary to have a nurse or more than one, if possible, depending on the number of surgeons there exist in the department or laboratory. The aim of this research is to give information on the importance of nurses as collaborators in a department or laboratory of experimental surgery. A department of experimental surgery without a nurse, as part of the staff, will never be able to carry out a good job, because they are as indispensable as surgeons, with independent and complementary functions typical of their profession.

Lic. Ileana Macías Hernández

2006-07-01

134

Experimental Error and Data Analysis in the Laboratory  

Science.gov (United States)

Laboratory experiments involve taking measurements of physical quantities. No measurement of any physical quantity is ever perfectly accurate, except possibly the counting of objects. The discrepancy between the measured value and the true value of the quantity may arise from different sources. No matter how-much effort is put into refinement of technique or into improvement of the instruments, the error can only be decreased in magnitude but never eliminated entirely. This article describes common types of errors, the ways to reduce the errors, and how to treat the data properly.

Harold Climers (University of Tennessee)

2003-01-31

135

Oak Ridge National Laboratory Research Reactor Experimenters' Guide  

International Nuclear Information System (INIS)

The Oak Ridge National Laboratory (ORNL) operates six research reactors dedicated to research and development work as well as radioisotope production. These reactors are used by ORNL and qualified non-ORNL research and development groups. The purpose of this report is to provide information to research personnel concerning the facilities and the ORNL research and services groups available to assist in the design, fabrication, operation, and post-operation examination of irradiation assemblies. Safety and operability reviews and quality assurance requirements are also described

136

Oak Ridge National Laboratory Research Reactor Experimenters' Guide  

International Nuclear Information System (INIS)

The Oak Ridge National Laboratory has three multipurpose research reactors which accommodate testing loops, target irradiations, and beam-type experiments. Since the experiments must share common or similar facilities and utilities, be designed and fabricated by the same groups, and meet the same safety criteria, certain standards for these have been developed. These standards deal only with those properties from which safety and economy of time and money can be maximized and do not relate to the intent of the experiment or quality of the data obtained. The necessity for, and the limitations of, the standards are discussed; and a compilation of general standards is included

137

Experimental investigation of failure time prediction in landslides  

Science.gov (United States)

Many new landslides often originate in old landslide areas, on pre-existing slip surfaces at residual shear strength condition. Previous laboratory investigations of drained displacement rates with time for pre-sheared surfaces have been very limited. A detailed survey of the literature reveals that all of the laboratory constant load compression tests, and a significant number of slope movement records that have been interpreted, correspond to ground conditions in the range of fully softened to intact shear strength. In fact, a few researchers mentioned stress-controlled direct shear and ring shear devices; however, they didn't present detailed test results and interpretation. A new laboratory normal- and shear-load-controlled direct shear device was designed for observing the deformation-time behaviour of pre-sheared surfaces, under constant normal and shear load. Estimating time to failure of a landslide based on measured creep movements have been suggested by various researchers. Some of the failure forecasting tools suggested in the literature are: relationship between minimum displacement rate before acceleration and time to failure; plot of inverse of velocity with time; and plot of acceleration with time. Based on the laboratory creep deformation tests on pre-existing shear surfaces, it is observed that at any shear stress level, the logarithm of the displacement rate decreases linearly with increase in the logarithm of time (until it reaches a minimum rate and starts increasing). The slope of this relationship is more or less independent of the shear stress level. A plot of minimum displacement rate immediately before acceleration, and time to failure is presented together with Saito and Uezawa (1961) data. It is confirmed that the time to failure is inversely proportional to the minimum displacement rate preceding the acceleration to failure. Inverse of velocity, and acceleration are also used as prediction tools, as was also used by other researchers. In the laboratory tests carried out in this study, a peak is observed in the inverse velocity-time plots (corresponding to the minimum displacement rate before acceleration), and then the inverse velocity values decrease toward zero (linearly or asymptotically) indicating the failure time. Acceleration and time to failure values are presented together with previous researchers' data from landslide case histories. Although the laboratory values of time to failure are very small (in the range of 1 to 100 minutes) and may seem to have limited use for real-life prediction, the lab test results confirm a linear trendline between acceleration and time to failure. This study is an attempt to investigate possible use of such forecasting tools. Although there are limitations in this laboratory study, the results show potential for forecasting tools to be useful with more data.

Huvaj-Sarihan, Nejan

2010-05-01

138

Numerical and experimental investigation of vortical flow-flame interaction  

Energy Technology Data Exchange (ETDEWEB)

A massively parallel coupled Eulerian-Lagrangian low Mach number reacting flow code is developed and used to study the structure and dynamics of a forced planar buoyant jet flame in two dimensions. The numerical construction uses a finite difference scheme with adaptive mesh refinement for solving the scalar conservation equations, and the vortex method for the momentum equations, with the necessary coupling terms. The numerical model construction is presented, along with computational issues regarding the parallel implementation. An experimental acoustically forced planar jet burner apparatus is also developed and used to study the velocity and scalar fields in this flow, and to provide useful data for validation of the computed jet. Burner design and laser diagnostic details are discussed, along with the measured laboratory jet flame dynamics. The computed reacting jet flow is also presented, with focus on both large-scale outer buoyant structures and the lifted flame stabilization dynamics. A triple flame structure is observed at the flame base in the computed flow, as is theoretically expected, but was not observable with present diagnostic techniques in the laboratory flame. Computed and experimental results are compared, along with implications for model improvements.

Najm, H.N.; Schefer, R.W.; Milne, R.B.; Mueller, C.J. [Sandia National Labs., Livermore, CA (United States); Devine, K.D.; Kempka, S.N. [Sandia National Labs., Albuquerque, NM (United States)

1998-02-01

139

Significance of different animal species in experimental models for in vivo investigations of hematopoiesis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Numerous discoveries in medicine are results of experiments on different animal species. The most frequently used animals in hematopoiesis investigations are laboratory mice and rats, but so-called big animals, such as pigs, sheep, cats, dogs, and monkeys, evolution-wise closer to humans have a place in experimental hematology as well. The specific problematics of a certain animal specie can lead to fundamental knowledge on certain aspects of the process of hematopoiesis end the biology of st...

Kova?evi?-Filipovi? Milica; Boži? Tatjana P.; Z?, Stevanovic? Jelka

2004-01-01

140

Experimental investigation of deformation mechanisms during shear-enhanced compaction in poorly lithified sandstone and sand  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Shear-enhanced compaction in shallow sandstone reservoirs has been investigated in laboratory experiments using high-pressure triaxial testing of poorly lithified sandstone and sand. We have studied the deformation mechanism involved during shear-enhanced compaction and controlling parameters for yield stress at varying confining pressures for sandstone/sand with different grain sizes, porosities, and packing. Experimental testing provides insights into the deformation mechanism during h...

Skurtveit, Elin; Torabi, Anita; Gabrielsen, Roy H.; Zoback, Mark D.

2013-01-01

 
 
 
 
141

Acute lung injury and acute respiratory distress syndrome: experimental and clinical investigations  

Directory of Open Access Journals (Sweden)

Full Text Available Acute lung injury (ALI or acute respiratory distress syndrome (ARDS can be associated with various disorders. Recent investigation has involved clinical studies in collaboration with clinical investigators and pathologists on the pathogenetic mechanisms of ALI or ARDS caused by various disorders. This literature review includes a brief historical retrospective of ALI/ARDS, the neurogenic pulmonary edema due to head injury, the long-term experimental studies and clinical investigations from our laboratory, the detrimental role of NO, the risk factors, and the possible pathogenetic mechanisms as well as therapeutic regimen for ALI/ARDS.

Hsing I Chen

2011-03-01

142

Experimental apparatus for tritium permeation studies in tritium process laboratory  

International Nuclear Information System (INIS)

An experimental apparatus has been developed to carry out tritium permeation experiments for candidate first-wall materials subjected to a high flux of low energy tritium ions, and installed in a glovebox. The experimental apparatus consists of five main systems; (1) a tritium ion source with energies variable from 20 to 1400 eV, (2) a main chamber system for direction an ion beam onto a heated target and for measuring various implantation-related experimental parameters by means of SIMS and AES, (3) a downstream system for measuring the permeated tritium through the target specimen by means of QMS, (4) a tritium supply and recovery system and (5) evacuation system. Operational tests with the system have yielded deuterium ion-beam with more than 90% deuterons and intensities from 2 x 1015 D+/cm2s at 200 eV to greater than 3 x 1015 D+/cm2s at 1000 eV. The energy width of the ion beam was about 10% of the beam energy ranging from 100 to 1400 eV. Baseline pressure as low as 9 x 0-9 Torr and 1 x 10-9 Torr have been achieved in the main chamber and downstream system, respectively

143

Experimental investigation on thermoelectric air conditioner driven by solar cells  

Energy Technology Data Exchange (ETDEWEB)

The thermoelectric devices can convert solar energy into a temperature difference to act as coolers or heater with the help of PV arrays, especially in the remote area without power network. The experiment device is composed of thermoelectric refrigeration modules, fan, air channel, cooling cabinet and temperature measurement system. The thermoelectric air conditioner (TEAC) system is tested with different working electric voltage of thermopile; its operational parameters are obtained for different operational conditions. The Coefficient of Performance (COP) is analyzed in experimental ways. The factors that affect the efficiency of TEAC are discussed on the basis of experimental investigation by air-cooled thermoelectric module and water-cooled thermoelectric module. (orig.)

Xu Lizhen; Li Yan; Qin Feng; Chen Changhe [Key Lab. for Thermal Science and Power Engineering, Ministry of Education of China, Dept. of Thermal Engineering, Tsinghua Univ., BJ (China)

2008-07-01

144

An experimental investigation of the occupied volume in polymers  

International Nuclear Information System (INIS)

In spite of a great deal of measurements concerning the relative free volume in polymers, the 'occupied volume' remained, up to the present, a concept not subjected to experimental investigations. However, the various theories on the free volume more or less explicitly refer to different, possible definitions of the occupied volume, in particular to its thermal behaviour. In the present work it is shown that it is possible to get information on the occupied volume by coupling positron annihilation lifetime spectroscopy and specific volume measurements; furthermore, some experimental data are discussed and compared to theoretical predictions. (orig.)

145

Experimental investigations on dynamic effects in impact notch bending tests  

International Nuclear Information System (INIS)

The dynamic behaviour of three point bending samples under impact stresses is examined experimentally. Various measuring processes, above all the shadow optics etching process are used. A quasi-static analysis is made by a simple spring/mass model to describe the stress behaviour quantitatively. Based on this, the dynamic effects in model experiments are measured quantitatively with dynamic correction functions and are discussed with reference to the wave processes in the sample. A systematic view of the effect of the many system parameters on the dynamic stress behaviour is obtained. Finally, examples show that the results of this model investigation can be transferred to other experimental conditions. (orig./HP)

146

Laboratory investigation of crushed salt consolidation and fracture healing  

Energy Technology Data Exchange (ETDEWEB)

A laboratory test program was conducted to investigate the consolidation behavior of crushed salt and fracture healing in natural and artificial salt. Crushed salt is proposed for use as backfill in a nuclear waste repository in salt. Artificial block salt is proposed for use in sealing a repository. Four consolidation tests were conducted in a hydrostatic pressure vessel at a maximum pressure of 2500 psi (17.2 MPa) and at room temperature. Three 1-month tests were conducted on salt obtained from the Waste Isolation Pilot Plant and one 2-month test was conducted on salt from Avery Island. Permeability was obtained using argon and either a steady-state or transient method. Initial porosities ranged from 0.26 to 0.36 and initial permeabilities from 2000 to 50,000 md. Final porosities and permeabilities ranged from 0.05 to 0.19 and from <10/sup -5/ md to 110 md, respectively. The lowest final porosity (0.05) and permeability (<10/sup -5/ md) were obtained in a 1-month test in which 2.3% moisture was added to the salt at the beginning of the test. The consolidation rate was much more rapid than in any of the dry salt tests. The fracture healing program included 20 permeability tests conducted on fractured and unfractured samples. The tests were conducted in a Hoek cell at hydrostatic pressures up to 3000 psi (20.6 MPa) with durations up to 8 days. For the natural rock salt tested, permeability was strongly dependent on confining pressure and time. The effect of confining pressure was much weaker in the artificial salt. In most cases the combined effects of time and pressure were to reduce the permeability of fractured samples to the same order of magnitude (or less) as the permeability measured prior to fracturing.

1987-01-01

147

Laboratory investigation of crushed salt consolidation and fracture healing  

International Nuclear Information System (INIS)

A laboratory test program was conducted to investigate the consolidation behavior of crushed salt and fracture healing in natural and artificial salt. Crushed salt is proposed for use as backfill in a nuclear waste repository in salt. Artificial block salt is proposed for use in sealing a repository. Four consolidation tests were conducted in a hydrostatic pressure vessel at a maximum pressure of 2500 psi (17.2 MPa) and at room temperature. Three 1-month tests were conducted on salt obtained from the Waste Isolation Pilot Plant and one 2-month test was conducted on salt from Avery Island. Permeability was obtained using argon and either a steady-state or transient method. Initial porosities ranged from 0.26 to 0.36 and initial permeabilities from 2000 to 50,000 md. Final porosities and permeabilities ranged from 0.05 to 0.19 and from -5 md to 110 md, respectively. The lowest final porosity (0.05) and permeability (-5 md) were obtained in a 1-month test in which 2.3% moisture was added to the salt at the beginning of the test. The consolidation rate was much more rapid than in any of the dry salt tests. The fracture healing program included 20 permeability tests conducted on fractured and unfractured samples. The tests were conducted in a Hoek cell at hydrostatic pressures up to 3000 psi (20.6 MPa) with durations up to 8 days. For the natural rock salt tested, permeability was strongly dependent on confining pressure and time. The effect of confining pressure was much weaker in the artificial salt. In most cases the combined effects of time and pressure were to reduce the permeability of fractured samples to the same order of magnitude (or less) as the permeability measured prior to fracturing

148

Experimental Methods in Neuroscience: An Undergraduate Neuroscience Laboratory Course for Teaching Ethical Issues, Laboratory Techniques, Experimental Design, and Analysis  

Science.gov (United States)

This article describes the development of a course which introduces students to issues of animal ethics, experimentation, and an Animal Care Facility. The experiments enable the students to gain confidence in collecting data, compiling large data sets, handling spreadsheets and graphing, applying appropriate statistics, and writing accurate and concise scientific reports in journal article format.

Adam C. Hall (Smith College;); Mary E. Harrington (Smith College;)

2003-11-01

149

Experimental investigation into dryout in deep debris beds  

International Nuclear Information System (INIS)

An experimental investigation of dryout in inductively-heated beds of steel spheres has been conducted. Bed depths ranged from 5 to 40 cm with particle sizes of 589-787, 1588, 3175, and 4783 microns, with a wide variation of overlying coolant depth. Water and acetone were used as the coolants. A surging phenomena was identified for some conditions, and a more definitive method of determining the experimental dryout was employed by extrapolating the time required for bed rewet. The ratio of dryout heat flux to the critical heat flux is found to be in good agreement with other experimental work, and is over-predicted for the larger particle-sizes by all of the current theoretical models. 14 refs

150

Experimental and analytical investigation of molten carbonate fuel cell stack  

International Nuclear Information System (INIS)

A high temperature molten carbonate fuel fell (MCFC) stack has been studied experimentally and computationally. A kW scale MCFC stack test station was designed and installed, and experimental investigations of the stack performance were conducted. A three-dimensional, variational parameter numerical model was developed and used to simulate the central fuel cell in the stack. Heat generation, mass transfer between anode and cathode and electrochemical characteristics of the fuel cell were considered in developing the model. The distributions of temperature on the cathode/current collector interface, current density, power density, water vapor concentration in the anode flow channel and and velocity for the fuel cell were simulated by solving the model using the computational fluid dynamics (CFD) technique. Simulation results show that the temperature, current and power densities reach their maximal values at the channel outlet. The comparison of the modeling results and experimental data shows good agreement

151

Experimental and analytical investigation of molten carbonate fuel cell stack  

Energy Technology Data Exchange (ETDEWEB)

A high temperature molten carbonate fuel fell (MCFC) stack has been studied experimentally and computationally. A kW scale MCFC stack test station was designed and installed, and experimental investigations of the stack performance were conducted. A three-dimensional, variational parameter numerical model was developed and used to simulate the central fuel cell in the stack. Heat generation, mass transfer between anode and cathode and electrochemical characteristics of the fuel cell were considered in developing the model. The distributions of temperature on the cathode/current collector interface, current density, power density, water vapor concentration in the anode flow channel and and velocity for the fuel cell were simulated by solving the model using the computational fluid dynamics (CFD) technique. Simulation results show that the temperature, current and power densities reach their maximal values at the channel outlet. The comparison of the modeling results and experimental data shows good agreement.

Yu Lijun [Institute of Thermal Energy Engineering, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Ren Gengpo [Institute of Thermal Energy Engineering, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)], E-mail: gengporen@126.com; Jiang Xiumin [Institute of Thermal Energy Engineering, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

2008-04-15

152

Experimental and analytical investigation of molten carbonate fuel cell stack  

Energy Technology Data Exchange (ETDEWEB)

A high temperature molten carbonate fuel fell (MCFC) stack has been studied experimentally and computationally. A kW scale MCFC stack test station was designed and installed, and experimental investigations of the stack performance were conducted. A three-dimensional, variational parameter numerical model was developed and used to simulate the central fuel cell in the stack. Heat generation, mass transfer between anode and cathode and electrochemical characteristics of the fuel cell were considered in developing the model. The distributions of temperature on the cathode/current collector interface, current density, power density, water vapor concentration in the anode flow channel and and velocity for the fuel cell were simulated by solving the model using the computational fluid dynamics (CFD) technique. Simulation results show that the temperature, current and power densities reach their maximal values at the channel outlet. The comparison of the modeling results and experimental data shows good agreement. (author)

Yu, Li-jun; Ren, Geng-po; Jiang, Xiu-min [Institute of Thermal Energy Engineering, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

2008-04-15

153

FOSS Variables FOSS Lifeboat Investigation: Developing Investigable Question, Investigation (Experimentation), and Communicating Results  

Science.gov (United States)

This activity is an extension of the FOSS Variables Lifeboat investigation. Students choose a lifeboats variable to investigate, write up an experiment based on the variable to be tested, test the variable, and create a lifeboats investigation poster to share their results.

Walvatne, Amy

154

Investigating Electromagnetic Induction through a Microcomputer-Based Laboratory.  

Science.gov (United States)

Describes a microcomputer-based laboratory experiment designed for high school students that very accurately analyzes Faraday's law of electromagnetic induction, addressing each variable separately while the others are kept constant. (Author/CCM)

Trumper, Ricardo; Gelbman, Moshe

2000-01-01

155

33 CFR 209.340 - Laboratory investigations and materials testing.  

Science.gov (United States)

...Corps of Engineers Divisions and Districts operating soils, concrete, water quality and hydraulic laboratories, and to the Inter-Agency...facility. (5) Performance of the work will not require expansion of normal facilities. (6) The work is within the...

2010-07-01

156

The hot cell laboratories for material investigations of the Institute for Safety Research  

Energy Technology Data Exchange (ETDEWEB)

Special facilities for handling and testing of irradiated specimens are necessary, to perform the investigation of activated material. The Institute for Safety Research has two hot cell laboratories: - the preparation laboratory and - the materials testing laboratory. This report is intended to give an overview of the available facilities and developed techniques in the laboratories. (orig.)

Viehrig, H.W.

1998-10-01

157

The hot cell laboratories for material investigations of the Institute for Safety Research  

International Nuclear Information System (INIS)

Special facilities for handling and testing of irradiated specimens are necessary, to perform the investigation of activated material. The Institute for Safety Research has two hot cell laboratories: - the preparation laboratory and - the materials testing laboratory. This report is intended to give an overview of the available facilities and developed techniques in the laboratories. (orig.)

158

Experimental investigation of contact resistance across pressed lead and aluminum  

Energy Technology Data Exchange (ETDEWEB)

In the proposed production of Accelerator Production of Tritium (APT) blanket module, lead will be encased in aluminum cladding. Energy transfer rate from the lead to the cooling water will be a function of the contact resistance between lead and aluminum. No data for contact resistance for this application exists in the literature. An experimental investigation has been conducted to determine thermal contact resistance between lead and aluminum in vacuum environment and also investigate the effect of pressure, surface roughness, and interface temperature on the contact resistance. The contact resistance decreases with the increase in contact pressure. Interface temperature and surface roughness do not affect the contact resistance significantly. There is slight increase in contact conductance with increasing temperature. The experimental results are generally well within acceptable accuracy and the data should be a good reference for the APT model.

Smith, A.C.

2000-03-22

159

Experimental investigation of contact resistance across pressed lead and aluminum  

International Nuclear Information System (INIS)

In the proposed production of Accelerator Production of Tritium (APT) blanket module, lead will be encased in aluminum cladding. Energy transfer rate from the lead to the cooling water will be a function of the contact resistance between lead and aluminum. No data for contact resistance for this application exists in the literature. An experimental investigation has been conducted to determine thermal contact resistance between lead and aluminum in vacuum environment and also investigate the effect of pressure, surface roughness, and interface temperature on the contact resistance. The contact resistance decreases with the increase in contact pressure. Interface temperature and surface roughness do not affect the contact resistance significantly. There is slight increase in contact conductance with increasing temperature. The experimental results are generally well within acceptable accuracy and the data should be a good reference for the APT model

160

Experimental and numerical investigation of orbital atherectomy: absence of cavitation  

Directory of Open Access Journals (Sweden)

Full Text Available A definitive, quantitative investigation has been performed to determine whether orbital atherectomy gives rise to cavitation. The investigation encompassed a synergistic interaction between in vitro experimentation and numerical simulation. The experimentation was performed in two independent fluid environments: 1 a transparent tube having a diameter similar to that of the superficial femoral artery and 2 a large, fluid-filled, open-topped container. All of the experimental and simulation work was based on the geometric model of the Diamondback 360 atherectomy device (Cardiovascular Systems, Inc., St. Paul, MN. Rotational speeds ranged from 80,000 to 214,000 rpm. The presence or absence of cavitation in the experiments was assessed by means of high-speed photography. The photographic images clearly display the fact that there was no cavitation. Flow visualization revealed the presence of fluid flows driven by pressure gradients created by the geometry of the rotating crown. The numerical simulations encompassed the fluid environments and the operating conditions of the experiments. The key result of the numerical simulation is that the minimum fluid pressure due to the rotational motion was approximately 50 times greater than the saturation vapor pressure of the fluid. Since the onset of cavitation requires that the fluid pressure falls below the saturation vapor pressure, the computational outcome strongly supports the experimental findings.

Ephraim M. Sparrow

2010-11-01

 
 
 
 
161

Experimental investigation of the serum albumin fascia microstructure  

Science.gov (United States)

The results of theoretical and experimental investigation of biological liquids are reported. Structural effects observed in fascias are considered with account of the molecular features of albumin and the concept of supramolecular organization of polymers. It is revealed that the morphology of human serum albumin fascias depends on the concentration and quality of the solvent. It is shown that the water-salt fascias of albumin are more structured than water solutions with the same concentration.

Buzoverya, M. E.; Shcherbak, Yu. P.; Shishpor, I. V.

2012-09-01

162

Experimental and theoretical investigation of anaerobic fluidized bed biofilm reactors  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This work presents an experimental and theoretical investigation of anaerobic fluidized bed reactors (AFBRs). The bioreactors are modeled as dynamic three-phase systems. Biochemical transformations are assumed to occur only in the fluidized bed zone. The biofilm process model is coupled to the system hydrodynamic model through the biofilm detachment rate; which is assumed to be a first-order function of the energy dissipation parameter and a second order function of biofilm thickness. Non-act...

Fuentes, M.; Mussati, M. C.; Aguirre, P. A.; Scenna, N. J.

2009-01-01

163

An Experimental Investigation of Risk Sharing and Adverse Selection  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Does adverse selection hamper the effectiveness of voluntary risk sharing? How do differences in risk profiles affect adverse selection? We experimentally investigate individuals’ willingness to share risks with others. Across treatments we vary how risk profiles differ between individuals. We find strong evidence for adverse selection if individuals risk profiles can be ranked according to first-order stochastic dominance and only little evidence for adverse selection if risk profiles can ...

Tausch, Franziska; Potters, Jan; Riedl, Arno

2013-01-01

164

Experimental investigations of turbulence in magnetized, partially ionized plasmas  

International Nuclear Information System (INIS)

An experimental investigation of turbulent fluctuations associated with gradient cross-field and Farley-Buneman instabilities is described. The experiments are carried out in magnetized plasma columns with an imposed radial electric field. Microwave scattering and probe measurements provide the plasma diagnostics. Particular attention is given to the varying characteristics of the turbulent spectra for both potential and density as a function of neutral gas pressure

165

Experimental Investigation on Selective Laser Melting of Glass  

Science.gov (United States)

Although laser-based Additive Manufacturing (AM) processes have been investigated extensively for use with different materials, fabrication of 3D glass objects using Selective Laser Melting (SLM) technology is not well developed even though it has many applications. As such an experimental investigation on the process parameters of glass powder using SLM process was conducted and the results are summarized in this paper. Multiple 3D objects were fabricated and analyzed. Lastly Scanning Electron Microcopy (SEM) of the manufactured objects as well as effect of process parameters on dimensional accuracy, surface quality, and the density of the fabricated parts are presented in this paper.

Fateri, Miranda; Gebhardt, Andreas; Thuemmler, Stefan; Thurn, Laura

166

Experimental and computational investigation into race car mechanics  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this study, experimental tests and Computational Fluid Dynamics are used to investigate the aerodynamic performance of two types of track-based racing cars. After the literature study, where automotive aerodynamics is discussed in very general terms, the air flow beneath a Formula One Grand Prix Racing Car is investigated. This is achieved by fitting the under-tray of a 30% scale model of the Parmalat Forti Ford FGO 1-95 with surface-static pressure ports and testing the model in a rolling...

Penning, Pieter Paulus

1999-01-01

167

Experimental and computational investigation into race car mechanics  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this study, experimental tests and Computational Fluid Dynamics are used to investigate the aerodynamic performance of two types of track-based racing cars. After the literature study, where automotive aerodynamics is discussed in very general terms, the air flow beneath a Formula One Grand Prix Racing Car is investigated. This is achieved by fitting the under-tray of a 30% scale model of the Parmalat Forti Ford FGO 1-95 with surface-static pressure ports and testing the model in a rolling...

Penning, Pieter Paulus

2006-01-01

168

Experimental investigation on an inherently actuated passive injection and depressurization system  

International Nuclear Information System (INIS)

ANSALDO has conceived an inherently actuated Passive Injection and Depressurization System (PIDS) to be used in Nuclear Power Plants (NPP). The adoption of the PIDS would allow to enhance the reliability of the Safety Systems, with the additional advantage of a simplification of the NPP current designs. Due to the innovative concept of this system, an experimental investigation has been performed at SIET Laboratory aimed at exploring the physical phenomena governing the behaviour of the system, with the basic goal to demonstrate the concept viability. After a brief description of the PIDS concept, the paper presents the experimental tests matrix and some results. The obtained experimental data confirm the validity of the concept, justifying and encouraging the continuation of the activities and calling for a further development and the execution of related experimental activities. (author). 10 figs, 2 tabs

169

A Computational and Experimental Investigation of Shear Coaxial Jet Atomization  

Science.gov (United States)

The instability and subsequent atomization of a viscous liquid jet emanated into a high-pressure gaseous surrounding is studied both computationally and experimentally. Liquid water issued into nitrogen gas at elevated pressures is used to simulate the flow conditions in a coaxial shear injector element relevant to liquid propellant rocket engines. The theoretical analysis is based on a simplified mathematical formulation of the continuity and momentum equations in their conservative form. Numerical solutions of the governing equations subject to appropriate initial and boundary conditions are obtained via a robust finite difference scheme. The computations yield real-time evolution and subsequent breakup characteristics of the liquid jet. The experimental investigation utilizes a digital imaging technique to measure resultant drop sizes. Data were collected for liquid Reynolds number between 2,500 and 25,000, aerodynamic Weber number range of 50-500 and ambient gas pressures from 150 to 1200 psia. Comparison of the model predictions and experimental data for drop sizes at gas pressures of 150 and 300 psia reveal satisfactory agreement particularly for lower values of investigated Weber number. The present model is intended as a component of a practical tool to facilitate design and optimization of coaxial shear atomizers.

Ibrahim, Essam A.; Kenny, R. Jeremy; Walker, Nathan B.

2006-01-01

170

Experimental Investigation into Electrical Discharge Machining of Stainless Steel 304  

Directory of Open Access Journals (Sweden)

Full Text Available This study presents the experimental investigation of the machining characteristics of austenitic stainless steel 304 through electric discharge machining. The effectiveness of the EDM process with stainless steel is evaluated in terms of the removal rate (MRR, the Tool Wear Rate (TWR and the surface roughness of the work-piece produced. The experimental work is conducted utilizing Die Sinking electrical discharge machine of AQ55L model. Cylindrical copper electrode having a size of Ø19x37 mm and positive polarity for electrode (reverse polarity is used to machine austenitic stainless steel 304 materials. The work material holds tensile strength of 580 and 290 MPa as yield strength. The size of the work-piece was Ø22x30 mm. Investigations indicate that increasing the peak current increases the MRR and the surface roughness. The TWR increases with peak ampere until 150 ? sec pulse-on time. From the experimental results no tool wear condition is noted for copper electrode at long pulse-on time with reverse polarity. The optimal pulse-on time is changed with high ampere.

M.M. Rahman

2011-01-01

171

Experimental investigation of transient thermoelastic effects in dynamic fracture  

International Nuclear Information System (INIS)

Thermoelastic effects in fracture are generally considered to be negligible at the benefit of the conversion of plastic work into heat. For the case of dynamic crack initiation, the experimental and theoretical emphasis has been put on the temperature rise associated with crack-tip plasticity. Nevertheless, earlier experimental work with polymers has shown that thermoelastic cooling precedes the temperature rise at the tip of a propagating crack (Fuller et al., 1975). Transient thermoelastic effects at the tip of a dynamically loaded crack have been theoretically assessed and shown to be significant when thermal conductivity is initially neglected. However, the fundamental question of the relation between crack initiation and thermal fields, both of transient nature, is still open. In this paper, we present an experimental investigation of the thermoelastic effect at the tip of fatigue cracks subjected to mixed-mode (dominant mode 1) dynamic loading. The material is commercial polymethylmethacrylate as an example of 'brittle' material. The applied loads, crack-tip temperatures and fracture time are simultaneously monitored to provide a more complete image of dynamic crack initiation. The corresponding evolution of the stress intensity factors is calculated by a hybrid-experimental numerical model. The results show that substantial crack-tip cooling develops initially to an extent which corroborates theoretical estimates. This effect is followed by a temperature rise. Fracture is shown to initiate during the early cooling phase, thus emphasizing the relevance of the phenomenon to dynamic crack initiation in this material as probably in other materials. (author)

172

Ribose 5-Phosphate Isomerase Investigations for the Undergraduate Biochemistry Laboratory  

Science.gov (United States)

The enzyme ribose 5-phosphate isomerase (RpiA) has many features that make it attractive as a focal point of a semester-long, advanced biochemistry laboratory for undergraduate students. The protein can easily and inexpensively be isolated from spinach using traditional purification techniques. Characterization of RpiA enzyme activity can be…

Jewett, Kathy; Sandwick, Roger K.

2011-01-01

173

A Collaborative, Investigative Recombinant DNA Technology Course with Laboratory  

Science.gov (United States)

A recombinant DNA technology course was designed to promote contextual, collaborative, inquiry-based learning of science where students learn from one another and have a sense of ownership of their education. The class stressed group presentations and critical reading and discussion of scientific articles. The laboratory consisted of two research…

Pezzementi, Leo; Johnson, Joy F.

2002-01-01

174

LABORATORY INVESTIGATION AND ANALYSIS OF A GROUND-WATER FLOWMETER  

Science.gov (United States)

The ground-water flowmeter system, model 30L, manufactured by K-V Associates, Inc., Falmouth, Massachusetts was tested under controlled laboratory conditions. The influence of slotted pipe schedule, slot orientation, backfill materials, endcap bags, isolated regions of high hydra...

175

Laboratory Investigation of Aerosol Formation in Combustion of Biomass  

International Nuclear Information System (INIS)

In this project the formation of aerosol particles and deposits in power plants during combustion of CO2-neutral fuels are investigated. For the experimental work a 173 cm long tubular furnace (diam=25 mm) with laminar flow is used. It is possible to control the temperature up to ? 1200 deg C in nine separate axial sections along the flue gas flow direction. In the first part of the reactor an inner tube is placed. In this inner tube a flow of inert nitrogen passes pellets of inert alumina impregnated with the salt to be volatilized (e.g. NaCl or KCl). The nitrogen gets saturated and by changing the temperature of the pellets it is possible to adjust the salt concentration in the gas. Other reactive gases (SO2, H2O, NO and O2/air) enter the reactor on the outside of the salt-containing alumina pipe. The temperature is kept constant in the first part of the reactor and is then decreased in the flow direction after a given length. The results obtained so far have shown that the homogeneous nucleation rate of pure salts depends on cooling rate, salt concentration and on the vapor pressure of the salt. Examples of results are shown at figure 1a. Here, two identical experiments are performed with two different salts. Since the vapor pressure of KCl is higher than for NaCl at the same temperature, a higher mass concentration of particles is obtained for this salt. Due to a lower salt concentration the number concentration of NaCl particles is higher, but the pa of NaCl particles is higher, but the particles are smaller. The particles are analyzed with a number of instruments, including scanning mobility particle sizer, low pressure cascade impactor and transition electron microscopy. Experiments with introduction of nucleation seeds in the inlet gas have been performed, and it has been found that a suppression of homogeneous nucleation can be observed at rather low number concentrations of seeds. Homogeneous nucleation is favored by rapid cooling and the critical seed concentration for suppression of nucleation is highly dependent on the rate of cooling. Experiments with sulfation of potassium chloride have been performed. By high-temperature filtering it has been found that potassium sulfate is the nucleating agent in aerosol formation during biomass combustion. In the future, the more advanced alkali-sulfur-chloride chemistry will be studied and the mechanisms leading to aerosol formation under biomass combustion conditions in power plants will be studied. The results will be analyzed by model studies including Computational Fluid Dynamics

176

Experimental investigation of blob physics in the TORPEX toroidal plasma  

Science.gov (United States)

Extensive experimental data from tokamaks, stellarators, reversed field pinches and basic linear devices reveal that particle and energy transport in the Scrape-Off-Layer is mostly non-diffusive and associated with the intermittent propagation of blobs. These are poloidally-localized regions extending along the field lines where the plasma pressure is enhanced compared to the surrounding plasma. Significant advances in understanding the mechanism for blob generation and the associated turbulent transport are achieved in the TORPEX toroidal device (R=1m, a=0.2m) using an experimental setup in which blobs are produced and diagnosed under controlled laboratory conditions. Full spatio-temporal imaging of blobs and associated energy and particle transport are obtained using conditional sampling of data from movable electrostatic probes with high spatial and temporal resolution. For the first time, the mechanism for plasma blob generation is experimentally identified on the basis of two-dimensional profiles of electron density and temperature, plasma potential and velocity fields. We show that blobs form from a radially elongated structure that is sheared off by the ExB flow. The structure originates from an interchange wave that increases in amplitude and extends radially in response to a decrease of the local radial pressure scale length. The dependence of the blob size upon the radial density gradient is also discussed. Two mechanisms for the transport across the magnetic field can be clearly quantified: the flux driven by the fluctuating density and potential associated with interchange modes, and the radially propagating blobs. Preliminary simulations of blob generation using a non-linear two-fluid numerical code are also presented.

Furno, Ivo

2007-11-01

177

Making controlled experimentation more informative in inquiry investigations  

Science.gov (United States)

This dissertation incorporates three studies that examine how the design of inquiry based science instruction, dynamic visualizations, and guidance for experimentation contribute to physics students' understanding of science. I designed a week-long, technology-enhanced inquiry module on car collisions that logs students' interactions with a visualization. Students studied the module and responded to pretests, posttests, and embedded prompts that assessed students' understanding of motion graphs and collisions. In Study 1, students (N=148) made large, significant overall pretest to posttest gains. Regression models showed that the propensity for students to conduct controlled trials was the strongest predictor of learning when controlling for prior knowledge and other experimentation measures. Successful learners employed a goal-directed experimentation approach that connected their experimentation strategy to content knowledge. Study 2 investigated the effect of limiting students' experimentation on their planning, strategies, and learning outcomes. Students (N=58) made large, significant overall pretest to posttest gains. Students constrained to twelve trials isolated variables in their experiments better than the unconstrained students. However, the constrained students significantly underperformed the unconstrained students on the module assessments, indicating that isolating variables during experimentation did not lead to improved learning outcomes. In Study 3, students (N=166) were assigned to conditions that prompted them either to isolate or compare variables. Both groups made moderate, significant pretest to posttest gains. Students in the compare treatment used more diverse experimentation strategies than students in the isolate treatment. Compare students made nuanced interpretations of collision events based on threshold values. Case studies illustrate how comparing rather than isolating variables helped students use wide-ranging strategies to reach complex insights. The findings illustrate how students can benefit from experimentation strategies that do not isolate variables. Spontaneous exploration can help students test new questions that arise from unexpected results, informing the design of controlled tests that better reveal subtle characteristics of the variables. Guidance that encourages students to compare rather than isolate variables may have important benefits, such as prompting students to search for distinctions among the variables. The findings have important implications for the design of inquiry-based science instruction.

McElhaney, Kevin Wei Hong

178

Numerical and experimental investigations of laser forming processes  

Science.gov (United States)

Laser forming is a recently developed and highly flexible metal forming process. It uses laser-induced thermal distortion to shape a metal workpiece without hard tooling or external forces. A number of issues concerning laser forming are not yet fully understood. Understanding these aspects of laser forming is a challenging problem of considerable academic interest and practical applications. Efforts are made to advance knowledge in these areas. Numerical simulation models using finite element analysis are developed. The simulation results are compared to, and are consistent with, the experimental observations under a wide range of conditions. The laser forming process is investigated under the condition of constant line energy. Under this condition, the effects of velocity on temperature, net energy input, strain rate and internal flow stress are studied. Their collective effects on deformation and microstructure are presented. The influence of the strain rate in laser forming is investigated. To isolate and effectively study the strain rate effects, which are temperature dependent, a "constant peak temperature" method is developed with the aid of the numerical modeling and solution. Under the constant peak temperature condition, the effects of strain rate on forming efficiency, residual stress and hardness of the formed parts are studied. A new laser-scanning scheme is postulated to obtain convex forming insensitive to the initial state. This postulate is validated by experimental and numerical results. Effects of the scanning scheme parameters on the certainty of the convex forming, and dependence of the bending angle on the Fourier number, laser power, and velocity are further investigated. Mechanisms of the process of laser bending of tubes are examined to better understand the deformation characteristics such as wall thickness variation, cross-section ovalization, bending radius, and asymmetry. Factors important to these characteristics are experimentally and numerically investigated. Temporal and spatial distributions of temperature and stress/strain obtained from experimentally validated simulation models are also used to better understand additional phenomena accompanying the process, and to help devise ways to improve the process. The process effects on hardness and microstructure variations are also investigated.

Li, Wenchuan

2000-10-01

179

Experimental Investigation of Creep Behavior of Reactor Vessel Lower Head  

International Nuclear Information System (INIS)

The authors report a study which aimed at experimentally and numerically investigating and characterizing the failure of a reactor pressure vessel (RPV) lower head due to thermal and pressure loads generated by a severe accident. They present the experimental apparatus which is based on a scaled version of the lower part of a TMI-like reactor pressure vessel without vessel skirt. They report and comment the results obtained during the first five experiments: uniform heating and non penetrations, centre-peaked heat flux and no penetrations, edge-peaked heat flux and no penetrations, uniform heating with penetrations, edge-peaked heat flux with penetrations. They compare the third and fifth experience (those with edge-peaked heat flux)

180

Theoretical and Experimental Investigations of DNA Open States  

CERN Document Server

This research is a review and assay of literature data on the properties of DNA open states. The states result from large fluctuations of a duplex and have a great influence on a wide range of biochemical processes, including electric charge transfer in DNA. A comparative analysis of kinetic and thermodynamic experimental data on DNA open states has been performed for a wide temperature range. Apparent contradictions between the data of different experiments have been explained. Based on differences in thermodynamic properties and other characteristics three different types of DNA open states have been identified; a modern definition of the term "open state" has been given. A brief review of simple mathematical models of DNA has been presented; in most of the models the state of every base pair is defined by one or two variables. The central problems of investigation of heterogeneous DNA within the approaches of the level considered are examined. The roles of every model group in experimental data interpretat...

Shigaev, A S; Lakhno, V D

2014-01-01

 
 
 
 
181

Experimental investigation of a strongly shocked gas bubble.  

Science.gov (United States)

A free-falling, spherical, soap-film bubble filled with argon is subjected to a planar M=2.88 shock in atmospheric nitrogen; vorticity is deposited on the surface of the bubble during shock interaction, and the Richtmyer-Meshkov instability ensues. The geometrical development of the shocked bubble is diagnosed with laser sheet imaging and a planar slice showing two cross sections of both the major vortex ring and a secondary vortex ring is revealed experimentally for the first time. Quantitative measurements of the experimental data include the vortex velocity defect, and subsequent circulation calculations, along with a new set of relevant length scales. The shock wave strength, leading to a post-shock compressible regime, allows the study of the instability development in a regime between low Mach number shock tube experiments and high Mach number laser driven experiments that has not been investigated previously. PMID:15904378

Ranjan, Devesh; Anderson, Mark; Oakley, Jason; Bonazza, Riccardo

2005-05-13

182

Computational and Experimental Investigations of Turbulent Flow Past Projectiles  

Science.gov (United States)

Experimental and computational investigations of turbulent flow past projectiles is modeled as axial flow past a cylinder with a free-spinning base. A subsonic wind tunnel with a forward-sting mounted spinning cylinder is used for experiments. In addition, a free-jet facility is used for benchmarking the experimental set up. Experiments are performed for a range of spin rates and free stream flow conditions. An anisotropic two-equation Reynolds-stress model that incorporates the effect of rotation-modified energy spectrum and swirl is used to perform computations for the flow past axially rotating cylinders. Both rigid cylinders as well as that of cylinders with free-spinning base are considered from a computational point of view. Applications involving the design of projectiles are discussed.

Mehmedagic, Igbal; Carlucci, Pasquale; Carlucci, Donald; Thangam, Siva

2008-11-01

183

Analytical and experimental investigation of mistuning in propfan flutter  

Science.gov (United States)

An analytical and experimental investigation of the effects of mistuning on propfan subsonic flutter was performed. The analytical model is based on the normal modes of a rotating composite blade and a three-dimensinal subsonic unsteady lifting surface aerodynamic theory. Theoretical and experimental results are compared for selected cases at different blade pitch angles, rotational speeds, and free-stream Mach numbers. The comparison shows a reasonably good agreement between theory and experiment. Both theory and experiment showed that combined mode shape, frequency, and aerodynamic mistuning can have a beneficial or adverse effect on blade damping depending on Mach number. Additional parametric results showed that alternative blade frequency mistuning does not have enough potential for it to be used as a passive flutter control in propfans similar to the one studied. It can be inferred from the results that a laminated composite propfan blade can be tailored to optimize its flutter speed by selecting the proper ply angles.

Kaza, Krishna Rao V.; Mehmed, Oral; Williams, Marc; Moss, Larry A.

1987-01-01

184

Experimental investigation of slope flows via image analysis techniques  

Science.gov (United States)

A vessel filled with distilled water is used to simulate the local circulation in the surroundings of an urban area that is situated in a mountain valley. The purpose of this study is to establish if the experimental setup is suitable for the investigation of katabatic and anabatic flows and their interaction with an urban heat island. Flow fields are derived by means of Feature Tracking and temperature fields are directly measured with thermocouples. The technique employed allows obtaining a high spatio-temporal resolution, providing robust statistics for the characterization of the fluid-dynamic field. General qualitative comparisons are made with expectations from analytical models. It appeared that the experimental setup as used in this study can be used for reproducing the phenomena occurring in the atmospheric boundary layer.

Moroni, Monica; Giorgilli, Marco; Cenedese, Antonio

2014-02-01

185

Numerical and laboratory investigations of transient and steady-state flow in a fractured core  

International Nuclear Information System (INIS)

An improved understanding of the ability of fractures to transmit water at matric potentials less than zero is essential for evaluating the ability of the rocks of Yucca Mountain, Nevada, to safely isolate nuclear waste. Numerical and experimental investigations of this subnuclear waste. Numerical and experimental investigations of this subject will help substantiate flux estimates of both liquid water and water vapor at Yucca Mountain, aid in assessing the effectiveness of capillary barriers at the contact between nonwelded and fractured welded units, and may provide insight as to the manner in which flow may become concentrated along specific pathways through a network of fractures under conditions of partial saturation. This paper summarizes some of the numerical and laboratory investigations that have been conducted at the US Geological Survey in Denver on a core of welded tuff containing a single fracture parallel to the core axis. The objectives of these investigations were to (1) explore the possibility that the unsaturated hydrologic properties of a fracture could be estimated by applying inverse techniques to the results of transient imbibition experiments, and (2) evaluate the accuracy of estimates of unsaturated fracture hydrologic properties derived from transient tests or numerical modeling through direct steady-state measurements. The core examined in these experiments is 0.0699 m long and has a radius of 0.0208 m. It was obtained from the open-quotes columnar zoneclose quotes of the Tiva Canyon member of the Paintbrush Tuff near Wren Wash on Yucca Mountain. 10 refs., 12 figs

186

Sprite discharges on Venus and Jupiter-like planets: a laboratory investigation  

CERN Document Server

Large sprite discharges at high atmospheric altitudes have been found to be physically similar to small streamer discharges in air at sea level density. Based on this understanding, we investigate possible sprite discharges on Venus or Jupiter-like planets through laboratory experiments on streamers in appropriate CO2-N2 and H2-He mixtures. First, the scaling laws are experimentally confirmed by varying the density of the planetary gasses. Then streamer diameters, velocities and overall morphology are investigated for sprites on Venus and Jupiter; they are quite similar to those on earth, but light emissions in the visible range are fainter by two orders of magnitude. The discharge spectra are measured; they are dominated by the minority species N2 on Venus, while signatures of both species are found on Jupiter-like planets. The spectrum of a fully developed spark on Venus is measured. We show that this spectrum is significantly different from the expected sprite spectrum.

Dubrovin, Daria; van Veldhuizen, Eddie; Ebert, Ute; Yair, Yoav; Price, Colin; 10.1029/2009JA014851

2010-01-01

187

21 CFR 312.160 - Drugs for investigational use in laboratory research animals or in vitro tests.  

Science.gov (United States)

...investigational use in laboratory research animals or in vitro tests. 312...Investigational Use in Laboratory Research Animals or In Vitro Tests § 312...investigational use in laboratory research animals or in vitro tests....

2010-04-01

188

21 CFR 312.160 - Drugs for investigational use in laboratory research animals or in vitro tests.  

Science.gov (United States)

...for investigational use in laboratory research animals or in vitro tests...for Investigational Use in Laboratory Research Animals or In Vitro Tests...for investigational use in laboratory research animals or in vitro...

2010-04-01

189

Investigation of impact crater processes using experimental and numerical techniques  

Science.gov (United States)

Impact events throughout the history of the Solar System have occurred at all scales, from craters produced by the hypervelocity impact of cosmic dust observed on lunar return samples, to the giant planet-sculpting impacts that have shaped the solid bodies of the Solar System. Investigating the impact process in the laboratory allows us to understand crater formation at a small scale where strength effects dominate however, it is difficult to scale directly to planetary sized impacts because gravity governs the cratering process at this large scale. Through computer modeling, it is possible to bridge the gap from small to large scale impact events. The influence of target porosity, saturation and an overlying water layer on crater morphology is investigated in the laboratory using a two-stage light gas gun to fire 1 mm diameter stainless steel projectiles at 5 km s"1 into sandstone targets. Larger craters were formed in the higher porosity targets and saturated targets. A critical water depth of 11.6 0.5 times the projectile diameter was required to prevent cratering in an unsaturated target, compared with 12.7 0.6 for saturated targets. The sensitivity of this critical water depth to impact velocity, projectile diameter and density is examined through use of the AUTODYN numerical code, for both laboratory and planetary scale impact events. Projectile survivability into water and sand targets is investigated in the lab for stainless steel and shale projectiles impacting at 2-5 km s"1 up to 30% of the projectile is found to survive. AUTODYN simulations show that basalt or sandstone meteorites impacting a simulated lunar surface survive the impact at velocities < 5 km s"1 and at a range of angles, which has positive implications for detecting terrestrial meteorites on the Moon. Groundwork has also been laid for the modelling of the deliberate collision of the SMART-1 spacecraft into the Moon. Finally, lunar and terrestrial impact events are simulated in order to quantify the depth' of excavation as a function of transient crater diameter for a range of crater and basin sizes. The output is found to lie in the range 0.08-0.15, with the South Pole Aitken basin excavating material to a depth comparable to the thickness of the farside crust.

Baldwin, Emily Clare

2008-12-01

190

Experimental Investigation of the Momentum Method for Determining Profile Drag  

Science.gov (United States)

Report presents the results of an experimental investigation conducted in the full-scale tunnel to determine the accuracy of the Jones and the Betz equations for computing profile drag from total and static pressure surveys in the wake of wings. Surveys were made behind 6 by 8-foot airfoils of the NACA 0009, and 0018 sections at zero lift and behind the NACA 0012 at positive lifts. The surveys were made at various spanwise positions and at distances behind the airfoil ranging from 0.05c to 3.00c.

Goett, Harry J

1939-01-01

191

Experimental investigation of non-planar sheared outboard wing planforms  

Science.gov (United States)

The outboard planforms of wings have been found to be of prime importance in studies of induced drag reduction. This conclusion is based on an experimental and theoretical study of the aerodynamic characteristics of planar and nonplanar outboard wing forms. Six different configurations; baseline rectangular, planar sheared, sheared with dihedral, sheared with anhedral, rising arc, and drooping arc were investigated for two different spans. Span efficiencies as much as 20 percent greater than baseline can be realized with nonplanar wing forms. Optimization studies show that this advantage can be achieved along with a bending moment benefit. Parasite drag and lateral stability estimations were not included in the analysis.

Naik, D. A.; Ostowari, C.

1988-01-01

192

Experimental investigation of system effects in stressed-skin elements  

DEFF Research Database (Denmark)

What kind of behaviour can be expected from stressed-skin elements at failure? To answer this question was a primary objective of the experimental investigation presented in this report. Systems of 3 roof units, each made of 5 parallel beams, have been tested for load-carrying capacity and behaviour at failure. Test results are compared with analytical calculations estimating the load-bearing capacity from predicted bending strength of each beam used in the system. The test results show that failure of one beam does not necessarily lead to failure of the whole system. This is an important issue in studies of system effects.

Dela Stang, B.; Isaksson, T.

2002-01-01

193

Experimental Investigation of Continuous-Wave Laser Ionization of Krypton  

Energy Technology Data Exchange (ETDEWEB)

This report describes experimental investigations of a method that uses continuous-wave (CW) lasers to ionize selected isotopes of krypton with high isotopic selectivity. The experiments show that the ionization rate is at least a factor of 100 lower than calculated with our model that has been described in a previous report. This discrepancy may be due to a much smaller excitation cross section that expected based on previous work and/or the aberrations in the ultraviolet beam used for the first step in the excitation. Additional problems with damage to mirrors, alignment instabilities, and manufacturers halting production of key products make this approach not worth further development at this time

Cannon, Bret D.; Shannon, Robert F.

2001-10-30

194

A review of experimental investigations on thermal phenomena in nanofluids  

Science.gov (United States)

Nanoparticle suspensions (nanofluids) have been recommended as a promising option for various engineering applications, due to the observed enhancement of thermophysical properties and improvement in the effectiveness of thermal phenomena. A number of investigations have been reported in the recent past, in order to quantify the thermo-fluidic behavior of nanofluids. This review is focused on examining and comparing the measurements of convective heat transfer and phase change in nanofluids, with an emphasis on the experimental techniques employed to measure the effective thermal conductivity, as well as to characterize the thermal performance of systems involving nanofluids.

Thomas, Shijo; Balakrishna Panicker Sobhan, Choondal

2011-05-01

195

Experimental investigation of stator flow in diagonal flow fan  

Science.gov (United States)

Experimental investigations were conducted for the internal flow of the stator of the diagonal flow fan. Corner separation near the hub surface and the suction surface of the stator blade are focused on. At the design flow rate, the values of the axial velocity and the total pressure at stator outlet decrease near the suction surface at around the hub surface by the influence of the corner wall. At low flow rate of 80-90 % of the design flow rate, the corner separation between the suction surface and the hub surface can be found, which become widely spread at 80 % of the design flow rate.

Wang, Jie; Kinoue, Yoichi; Shiomi, Norimasa; Setoguchi, Toshiaki; Kaneko, Kenji; Jin, Yingzi

2008-12-01

196

Experimental investigation of edge localised modes in JET  

International Nuclear Information System (INIS)

Edge Localised Modes (ELMs) in the JET tokamak have been studied experimentally, using density profile and fluctuation data from a multichannel reflectometer and temperature profile data from an ECE heterodyne radiometer. The following topics have been investigated: The radial extent and localisation of the density and temperature profile perturbations caused by the ELMs. Fluctuations in the density and magnetic field in connection with the ELMs. The correlation between the repetition frequency of the L-H transition ELMs, and the plasma edge temperature and density. Trajectories in n-T space prior to ELMs later in the H-mode. (au) (39 refs.)

197

Experimental investigation of effects of external loads on erosive wear  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Purpose: The purpose of the paper is to investigate effects of external loads on erosive wear.Design/methodology/approach: In this experimental study, specimens were placed on specially designed a specimen holder and then, external tensile loads corresponding to 0%, 20%, 40% and 60% of the specimen’s yield strength were applied on the specimens. For every load step, the specimens were subjected to 15º, 30º, 45º, 60º, 75º and 90º of erodent impact angles. At the end of the tests, effec...

Imrek, H.; Bagci, M.; Khalfan, O. M.

2009-01-01

198

Physical properties of alpine rocks : a laboratory investigation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this study, basic physical properties of rocks from the Swiss Alp have been determined and analyzed in an integrated manner. Laboratory measurements have carried out on bulk density, matrix density, thermal conductivity, magnetic susceptibility and P-wave velocity. Thermal conductivity has been measured using a QTM (Quick thermal meter) apparatus. By analyzing the difference in thermal conductivity and its anisotropy under dry and saturated states, the pore configuration of most of the mea...

Gong, Gangyan

2005-01-01

199

Physical properties of alpine rocks: a laboratory investigation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this study, basic physical properties of rocks from the Swiss Alp have been determined and analyzed in an integrated manner. Laboratory measurements have carried out on bulk density, matrix density, thermal conductivity, magnetic susceptibility and P-wave velocity. Thermal conductivity has been measured using a QTM (Quick thermal meter) apparatus. By analyzing the difference in thermal conductivity and its anisotropy under dry and saturated states, the pore configuration of most of the mea...

Gong, Gangyan; Wagner, Jean-jacques; Gorin, Georges

2006-01-01

200

Integral Test Facility PKL: Experimental PWR Accident Investigation  

International Nuclear Information System (INIS)

Investigations of the thermal-hydraulic behavior of pressurized water reactors under accident conditions have been carried out in the PKL test facility at AREVA NP in Erlangen, Germany for many years. The PKL facility models the entire primary side and significant parts of the secondary side of a pressurized water reactor (PWR) at a height scale of 1:1. Volumes, power ratings and mass flows are scaled with a ratio of 1:145. The experimental facility consists of 4 primary loops with circulation pumps and steam generators (SGs) arranged symmetrically around the reactor pressure vessel (RPV). The investigations carried out encompass a very broad spectrum from accident scenario simulations with large, medium, and small breaks, over the investigation of shutdown procedures after a wide variety of accidents, to the systematic investigation of complex thermal-hydraulic phenomena. This paper presents a survey of test objectives and programs carried out to date. It also describes the test facility in its present state. Some important results obtained over the years with focus on investigations carried out since the beginning of the international cooperation are exemplarily discussed.

 
 
 
 
201

Laboratory prototype for experimental validation of MR-guided radiofrequency head and neck hyperthermia.  

Science.gov (United States)

Clinical studies have established a strong benefit from adjuvant mild hyperthermia (HT) to radio- and chemotherapy for many tumor sites, including the head and neck (H&N). The recently developed HYPERcollar allows the application of local radiofrequency HT to tumors in the entire H&N. Treatment quality is optimized using electromagnetic and thermal simulators and, whenever placement risk is tolerable, assessed using invasively placed thermometers. To replace the current invasive procedure, we are investigating whether magnetic resonance (MR) thermometry can be exploited for continuous and 3D thermal dose assessment. In this work, we used our simulation tools to design an MR compatible laboratory prototype applicator. By simulations and measurements, we showed that the redesigned patch antennas are well matched to 50 ? (S11temperature increase of 4.5 °C in 6 min is feasible at the center of a cylindrical fat/muscle phantom. Temperature measurements using the MR scanner confirmed the focused heating capabilities and MR compatibility of the setup. We conclude that the laboratory applicator provides the possibility for experimental assessment of the feasibility of hybrid MR-HT in the H&N region. This versatile design allows rigorous analysis of MR thermometry accuracy in increasingly complex phantoms that mimic patients' anatomies and thermodynamic characteristics. PMID:24699230

Paulides, M M; Bakker, J F; Hofstetter, L W; Numan, W C M; Pellicer, R; Fiveland, E W; Tarasek, M; Houston, G C; van Rhoon, G C; Yeo, D T B; Kotek, G

2014-05-01

202

Experimental study of hard-X ray emission from laboratory sparks  

Science.gov (United States)

We present the characterization of hard-X rays produced by meter-long laboratory sparks carried out at the high-voltage laboratory of RSE, Milano, Italy. Sparks are known to emit X-rays when positive and negative streamers connect, before breakdown. Numerical simulations suggest that X-rays are produced by Bremsstrahlung in air by electrons accelerated to the runaway regime in the high electric field at the streamers tip. Positive meter-long discharges are produced by a Marx generator loaded by a meter-long air gap formed by a spherical anode and a conical-shaped cathode. Maximum voltage at breakdown is about 1 MV. We investigate the production of X-rays by means of an array of scintillation detectors deployed around the cathode. Each detector is a 2'' NaI(Tl) scintillating crystal coupled to a photomultiplier tube (PMT). Each detector is battery-powered and enclosed in a metallic housing for EM shielding. Analog signal output is trasmitted to a shielded control room by means of optical fibre tranceivers, and then collected by a fast digitizer. We present the experimental setup and first results concerning detection efficiency, energy spectra, and geometrical distribution of the emission.

Marisaldi, Martino; Rizzi, Rolando; Levi, Giuseppe; Malgesini, Roberto; Villa, Andrea; Mazza, Paolo; Labanti, Claudio; Fuschino, Fabio; Campana, Riccardo; Bianchini, David; Brancaccio, Rossella; Montanari, Alessandro; Patrizii, Laura

2014-05-01

203

Promising lines of investigations in the realms of laboratory astrophysics with the aid of powerful lasers  

International Nuclear Information System (INIS)

The results of work on choosing and substantiating promising lines of research in the realms of laboratory astrophysics with the aid of powerful lasers are presented. These lines of research are determined by the possibility of simulating, under laboratory conditions, problematic processes of presentday astrophysics, such as (i) the generation and evolution of electromagnetic fields in cosmic space and the role of magnetic fields there at various spatial scales; (ii) the mechanisms of formation and evolution of cosmic gamma-ray bursts and relativistic jets; (iii) plasma instabilities in cosmic space and astrophysical objects, plasma jets, and shock waves; (iv) supernova explosions and mechanisms of the explosion of supernovae featuring a collapsing core; (v) nuclear processes in astrophysical objects; (vi) cosmic rays and mechanisms of their production and acceleration to high energies; and (vii) astrophysical sources of x-ray radiation. It is shown that the use of existing powerful lasers characterized by an intensity in the range of 1018–1022 W/cm2 and a pulse duration of 0.1 to 1 ps and high-energy lasers characterized by an energy in excess of 1 kJ and a pulse duration of 1 to 10 ns makes it possible to perform investigations in laboratory astrophysics along all of the chosen promising lines. The results obtained by experimentally investigating laser plasma with the aid of the laser facility created at Central Research Institute y created at Central Research Institute of Machine Building (TsNIIMash) and characterized by a power level of 10 TW demonstrate the potential of such facilities for performing a number of experiments in the realms of laboratory astrophysics.

204

Experimental investigation and model development for a harmonic drive transmission  

Science.gov (United States)

Harmonic drive transmissions (HDTs) are compact, low-backlash, high-ratio, high-resolution rotary motion transmissions. One application to benefit from these attributes is the revolute joint robot. Engineers at the Advanced Photon Source (APS) are investigating the use of this type of robot for the positioning of an x-ray detector; understanding the properties of the robot components is crucial to modeling positioner behavior. The robot bearing elements had been investigated previously, leaving the transmission as the missing component. While the benefits of HDTs are well known, the disadvantages, including fluctuating dissipation characteristics and nonlinear stiffness, are not understood as well. These characteristics can contribute uncontrolled dynamics to the overall robot performance. A dynamometer has been constructed at the APS to experimentally measure the HDT's response. Empirical torque and position data were recorded for multiple transmission load cases and input conditions. In turn, a computer model of the dynamometer HDT system was constructed to approximate the observed response.

Preissner, Curt; Shu, Deming; Royston, Thomas J.

2007-09-01

205

Experimental investigation and performance test of heavy duty torque converter  

International Nuclear Information System (INIS)

The present study is an investigation on the characteristics of heavy load toque converter by experimental process. To get the dynamic performance, the dynamometer was used with a parameters of speed, torque, oil pressure and oil flux, etc. The torque converter was tested for various input speed, output oil pressure and input oil flow rate. All experiments were investigated in case that the speed ratio is increased. The torque ratio and capacity factor was in inverse proportion to speed. Engine revolution had a more effects at region of low speed ratio. But, the opposite phenomena were represented increase of efficiency. In result of this experiments, the characteristics of torque converter were not influenced by oil pressure and oil flux

206

Experimental investigation and model development for a harmonic drive transmission  

International Nuclear Information System (INIS)

Harmonic drive transmissions (HDTs) are compact, low-backlash, high-ratio, high-resolution rotary motion transmissions. One application to benefit from these attributes is the revolute joint robot. Engineers at the Advanced Photon Source (APS) are investigating the use of this type of robot for the positioning of an x-ray detector; understanding the properties of the robot components is crucial to modeling positioner behavior. The robot bearing elements had been investigated previously, leaving the transmission as the missing component. While the benefits of HDTs are well known, the disadvantages, including fluctuating dissipation characteristics and nonlinear stiffness, are not understood as well. These characteristics can contribute uncontrolled dynamics to the overall robot performance. A dynamometer has been constructed at the APS to experimentally measure the HDT's response. Empirical torque and position data were recorded for multiple transmission load cases and input conditions. In turn, a computer model of the dynamometer HDT system was constructed to approximate the observed response.

207

Experimentally investigate ionospheric depletion chemicals in artificially created ionosphere  

International Nuclear Information System (INIS)

A new approach for investigating ionosphere chemical depletion in the laboratory is introduced. Air glow discharge plasma closely resembling the ionosphere in both composition and chemical reactions is used as the artificially created ionosphere. The ionospheric depletion experiment is accomplished by releasing chemicals such as SF6, CCl2F2, and CO2 into the model discharge. The evolution of the electron density is investigated by varying the plasma pressure and input power. It is found that the negative ion (SF6?, CCl2F2?) intermediary species provide larger reduction of the electron density than the positive ion (CO2+) intermediary species. The negative ion intermediary species are also more efficient in producing ionospheric holes because of their fast reaction rates. Airglow enhancement attributed to SF6 and CO2 releases agrees well with the published data. Compared to the traditional methods, the new scheme is simpler to use, both in the release of chemicals and in the electron density measurements. It is therefore more efficient for investigating the release of chemicals in the ionosphere.

208

Experimentally investigate ionospheric depletion chemicals in artificially created ionosphere  

Energy Technology Data Exchange (ETDEWEB)

A new approach for investigating ionosphere chemical depletion in the laboratory is introduced. Air glow discharge plasma closely resembling the ionosphere in both composition and chemical reactions is used as the artificially created ionosphere. The ionospheric depletion experiment is accomplished by releasing chemicals such as SF{sub 6}, CCl{sub 2}F{sub 2}, and CO{sub 2} into the model discharge. The evolution of the electron density is investigated by varying the plasma pressure and input power. It is found that the negative ion (SF{sub 6}{sup -}, CCl{sub 2}F{sub 2}{sup -}) intermediary species provide larger reduction of the electron density than the positive ion (CO{sub 2}{sup +}) intermediary species. The negative ion intermediary species are also more efficient in producing ionospheric holes because of their fast reaction rates. Airglow enhancement attributed to SF{sub 6} and CO{sub 2} releases agrees well with the published data. Compared to the traditional methods, the new scheme is simpler to use, both in the release of chemicals and in the electron density measurements. It is therefore more efficient for investigating the release of chemicals in the ionosphere.

Liu Yu; Cao Jinxiang; Wang Jian; Zheng Zhe; Xu Liang; Du Yinchang [CAS Key Laboratory of Basic Plasma Physics, Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

2012-09-15

209

Experimentally investigate ionospheric depletion chemicals in artificially created ionosphere  

Science.gov (United States)

A new approach for investigating ionosphere chemical depletion in the laboratory is introduced. Air glow discharge plasma closely resembling the ionosphere in both composition and chemical reactions is used as the artificially created ionosphere. The ionospheric depletion experiment is accomplished by releasing chemicals such as SF6, CCl2F2, and CO2 into the model discharge. The evolution of the electron density is investigated by varying the plasma pressure and input power. It is found that the negative ion (SF6-, CCl2F2-) intermediary species provide larger reduction of the electron density than the positive ion (CO2+) intermediary species. The negative ion intermediary species are also more efficient in producing ionospheric holes because of their fast reaction rates. Airglow enhancement attributed to SF6 and CO2 releases agrees well with the published data. Compared to the traditional methods, the new scheme is simpler to use, both in the release of chemicals and in the electron density measurements. It is therefore more efficient for investigating the release of chemicals in the ionosphere.

Liu, Yu; Cao, Jinxiang; Wang, Jian; Zheng, Zhe; Xu, Liang; Du, Yinchang

2012-09-01

210

Experimental investigation of a twice-shocked spherical density inhomogeneity  

International Nuclear Information System (INIS)

Results are presented from a series of experiments investigating the behavior of a twice-shocked spherical density inhomogeneity. The experiments are performed at the Wisconsin Shock Tube Laboratory's (WiSTL) 9 m long vertical shock tube with a square internal cross section, 0.254 m on a side, equipped with a pneumatically retracting bubble injector. Baroclinic vorticity deposition occurs during the interaction of the shock wave with the spherical density inhomogeneity, leading to the formation of a vortex ring. The incident shock wave reflects from the tube end wall and interacts with the translating vortex ring (reshock), resulting in additional vorticity deposition. After reshock, the ambient particle velocity is zero and the subsequent translational motion of the vortex ring is due entirely to the net circulation present. Circulation models are investigated for the reshock scenario and a new model is developed and applied to both once-shocked and reshocked scenarios. Two Atwood numbers (A=0.17, 0.68) and three initial Mach numbers (M=1.35, 2.00, 2.33) are investigated. High-speed cameras at 10 000 fps are used to observe the development of the vortex ring after reshock. An understanding of the shock-induced compression and vortex generation is vital to the future study of turbulent combustion initiated by the shock focusing phenomenon.

211

Experimental investigation of effects of external loads on erosive wear  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: The purpose of the paper is to investigate effects of external loads on erosive wear.Design/methodology/approach: In this experimental study, specimens were placed on specially designed a specimen holder and then, external tensile loads corresponding to 0%, 20%, 40% and 60% of the specimen’s yield strength were applied on the specimens. For every load step, the specimens were subjected to 15º, 30º, 45º, 60º, 75º and 90º of erodent impact angles. At the end of the tests, effects of external loads and impingement angles on erosive wear were studied. In the experimental set, dry and compressed air was used to impinge erodents onto the test specimens and subsequent wear was investigated. During the tests, the impingement angles were adjusted by turning the specimen holder around its axis. Erodent particles used were SAE G40 having internal uniform martensitic structure and angular geometry. Determination of erodents speed was achieved with the help of the Rotating Double Disc Method. The speed used in the tests was 30 m/s.Findings: At the end of the tests, erosive wear rates were obtained as functions of stresses and impingement angles. Graphs showing variations of erosive wear rates for load values obtained against every impingement angle and yield stress were drawn. Critical impingement angle and load values at which maximum erosion rate was obtained were determined.Research limitations/implications: In researches made on erosive wears so far; there are only few studies dealing with the effects of external loads on the specimens subjected to erosive wear. By considering that stresses may affect the erosive wear, the stress state around contact area as well as material properties, this experimental study has thus, investigated likely effects of stresses on the erosive wear. With the help of the designed special specimen holder, the specimens were subjected to tensile stresses that are lower than the yield strength of the material and then the erosive wear was investigated.Originality/value: The investigations of effects of external loads on erosive wear.

H. Imrek

2009-01-01

212

An Experimental Investigation of the Scaling of Columnar Joints  

CERN Document Server

Columnar jointing is a fracture pattern common in igneous rocks in which cracks self-organize into a roughly hexagonal arrangement, leaving behind an ordered colonnade. We report observations of columnar jointing in a laboratory analog system, desiccated corn starch slurries. Using measurements of moisture density, evaporation rates, and fracture advance rates as evidence, we suggest an advective-diffusive system is responsible for the rough scaling behavior of columnar joints. This theory explains the order of magnitude difference in scales between jointing in lavas and in starches. We investigated the scaling of average columnar cross-sectional areas due to the evaporation rate, the analog of the cooling rate of igneous columnar joints. We measured column areas in experiments where the evaporation rate depended on lamp height and time, in experiments where the evaporation rate was fixed using feedback methods, and in experiments where gelatin was added to vary the rheology of the starch. Our results suggest...

Goehring, L; Morris, S; Goehring, Lucas; Lin, Zhenqun; Morris, Stephen

2006-01-01

213

The Monotonicity Puzzle: An Experimental Investigation of Incentive Structures  

Directory of Open Access Journals (Sweden)

Full Text Available Non-monotone incentive structures, which - according to theory - are able to induce optimal behavior, are often regarded as empirically less relevant for labor relationships. We compare the performance of a theoretically optimal non-monotone contract with a monotone one under controlled laboratory conditions. Implementing some features relevant to real-world employment relationships, our paper demonstrates that, in fact, the frequency of income-maximizing decisions made by agents is higher under the monotone contract. Although this observed behavior does not change the superiority of the non-monotone contract for principals, they do not choose this contract type in a significant way. This is what we call the monotonicity puzzle. Detailed investigations of decisions provide a clue for solving the puzzle and a possible explanation for the popularity of monotone contracts.

Jeannette Brosig

2010-05-01

214

Experimental investigation of driven magnetic reconnection in TS-3 device  

International Nuclear Information System (INIS)

Mechanisms for fast/driven magnetic reconnection have been investigated by measuring 2.5-dimensional current sheet structures of laboratory merging plasmas. The reconnection speed is observed to increase with decreasing magnetic field component parallel to the 'X-point' of the magnetic field line and with increasing external force to compress the current sheet. The measured resistivity of the current sheet is found to increase significantly right after the current sheet is compressed shorter than its ion Larmor radius. The anomalous resistivity of the current sheet caused by the finite Larmor radius effect is concluded essential to the fast/driven-type reconnection whose speed depends strongly on the X-line field and the external force. (author)

215

Experimental investigation of helical structures in swirling flows  

International Nuclear Information System (INIS)

Highlights: ? A swirl tube with variable exit orifices was experimentally investigated. ? Magnetic resonance velocimetry was applied to measure 3D3C velocity fields. ? One major observation is the occurrence of a three-layered flow structure. ? A new velocity zone of swirl flows was discovered: A fast jet in the core of the flow. ? Excentrical exit orifice trigger the development of helical structures in the flow. - Abstract: In this investigation the flow in a generic swirl tube with a tangential double-inlet swirl generator and variable exit orifices was experimentally investigated. Using magnetic resonance velocimetry (MRV) three-dimensional, three-component velocity fields were measured for two different Reynolds numbers: 10,000 and 15,000, and for three different exit orifices. The swirl generator had a fixed geometry producing an initial swirl number of 1.6 for all cases. One major observation is the occurrence of a three-layered flow structure. An annular main flow was surrounded by a recirculation zone, as reported in previous literature. However, this recirculation zone – also of an annular shape – exhibited a third layer inside: a thin, high speed jet in the center of the tube with the same flow direction as the main flow. Therefore, the conventional classification of swirling flows into ring and recirculation zone, has to be extended by a core zone. This three-layered flow structure develops independently of the exit configuration. Helical strt configuration. Helical structures were observed in the near-wall region for all cases investigated. Applying an eccentric exit orifice results in the occurrence of strong stationary helical structures not only in the near-wall region but also in the center of the tube. The results, deviating significantly from previous results in the literature, underline the need for more detailed research on the topic of cyclone type flows.

216

Experimental and numerical investigations of shape memory alloy helical springs  

Science.gov (United States)

Shape memory alloys (SMAs) belong to the class of smart materials and have been used in numerous applications. Solid phase transformations induced either by stress or temperature are behind the remarkable properties of SMAs that motivate the concept of innovative smart actuators for different purposes. The SMA element used in these actuators can assume different forms and a spring is an element usually employed for this aim. This contribution deals with the modeling, simulation and experimental analysis of SMA helical springs. Basically, a one-dimensional constitutive model is assumed to describe the SMA thermomechanical shear behavior and, afterwards, helical springs are modeled by considering a classical approach for linear-elastic springs. A numerical method based on the operator split technique is developed. SMA helical spring thermomechanical behavior is investigated through experimental tests performed with different thermomechanical loadings. Shape memory and pseudoelastic effects are treated. Numerical simulations show that the model results are in close agreement with those obtained by experimental tests, revealing that the proposed model captures the general thermomechanical behavior of SMA springs.

Aguiar, Ricardo A. A.; Savi, Marcelo A.; Pacheco, Pedro M. C. L.

2010-02-01

217

Computational and Experimental Investigations of Boundary Layer Tripping  

Directory of Open Access Journals (Sweden)

Full Text Available Supersonic flow over a tapered body of revolution has been investigated both experimentally and numerically. The experimental study consisted of a series of wind tunnel tests on an ogive-cylinder body. Static pressure distributions on the body surfaces at several longitudinal cross sections, as well as the boundary layer profiles at various angles of attack have been measured. Further, the flow around the model was visualized using Schlieren technique. Tests with a natural development of the boundary layer and with tripping were also carried out. All tests were conducted in the trisonic wind tunnel of Qadr Research Center. Our results show that artificial boundary layer tripping has minor effect on the static surface pressure distribution (depending on its diameter and installation location, while the changes in total pressure around the body were significant. Tripping the boundary layer increased its thickness, changed its profile particularly near the body surface. Two oblique shock waves were formed in the front and behind the trip wire. In this study, using multi-block grid, the thin layer Navier-Stokes (TLNS equations were solved around the above models. Also patched method was used near the interfaces. Good agreements were achieved when the numerical results were compared with the corresponding experimental data.

M.R Heidari

2010-01-01

218

Experimental and numerical investigations of shape memory alloy helical springs  

International Nuclear Information System (INIS)

Shape memory alloys (SMAs) belong to the class of smart materials and have been used in numerous applications. Solid phase transformations induced either by stress or temperature are behind the remarkable properties of SMAs that motivate the concept of innovative smart actuators for different purposes. The SMA element used in these actuators can assume different forms and a spring is an element usually employed for this aim. This contribution deals with the modeling, simulation and experimental analysis of SMA helical springs. Basically, a one-dimensional constitutive model is assumed to describe the SMA thermomechanical shear behavior and, afterwards, helical springs are modeled by considering a classical approach for linear-elastic springs. A numerical method based on the operator split technique is developed. SMA helical spring thermomechanical behavior is investigated through experimental tests performed with different thermomechanical loadings. Shape memory and pseudoelastic effects are treated. Numerical simulations show that the model results are in close agreement with those obtained by experimental tests, revealing that the proposed model captures the general thermomechanical behavior of SMA springs

219

Experimental and three-dimensional finite element investigation of fatigue  

Science.gov (United States)

Materials often fail at cyclic loads that are lower than their ultimate strength or even their yield strength due to progressive internal material degradation; commonly known as fatigue. Moreover, there is a wide scatter in observed fatigue lives of mechanical components operating under identical loading conditions. The randomness of fatigue failure is considered to be linked to basic microstructural effects such as random microstructure topology and the initiation/growth of cracks along inter/transgranular planes. Several modeling approaches have been previously presented ranging from 2D discrete element to 3D Finite Element methods with explicit representation of microstructure topology and continuum damage mechanics to capture dispersion in rolling contact fatigue life and fatigue spalling. There is, however, a need to compare the modeling approach with experimental fatigue test conditions in order to verify and as required enhance the modeling approach to capture observed fatigue failure. This dissertation presents experimental test results and three-dimensional modeling approach that capture fatigue failure. The three-dimensional modeling approach is enhanced according to the experimental observations to consider inter/trans granular failure, different modes of fatigue initiation and propagation and finally for considering effect of plasticity in fatigue of rolling contacts. The following phenomena have been investigated: (1) Fatigue of microbeams: (a )Results of fatigue life and failure from 3D modeling of intergranular fatigue in microbeams are compared with experimental observations reported in literature (2) Tensile fatigue of thin sheets: (a) A test rig with a new grip and alignment system is developed to address the challenges associated with thin sheet testing and conduct fatigue experiments. (b) The 3D fatigue model is enhanced to capture the dominant transgranular fatigue observed in the experiments. The observed and modeled fatigue life and failure are compared. (3) Torsion fatigue of bearing steel variants: (a) Custom grips are developed and integrated with an MTS torsion test rig to undertake torsion testing of various bearing steel variants. (b) A model for torsional fatigue failure was developed and the experimental and numerical results are compared. (4) Rolling contact fatigue: (a) An improved 3D RCF model is developed which is computationally efficient and accurate compared to a previously published model. (b) The 3D fatigue model is enhanced to investigate the effects of plasticity and fatigue damage due to plastic strain accumulation on rolling contact fatigue.

Bomidi, John A. R.

220

The colloid investigations conducted at the Aespoe Hard Rock Laboratory during 2000-2004  

Energy Technology Data Exchange (ETDEWEB)

In 2000, SKB decided to initiate an international colloid project at the Aespoe Hard Rock Laboratory in Sweden. The objectives of the colloid project are to: (i) study the role of bentonite as a colloid source, (ii) verify the background colloid concentration at Aespoe HRL and, (iii) investigate the potential for colloid formation/transport in natural groundwater concentrations. The experimental concepts for the colloid project are: laboratory experiments with bentonite, background field measurements of natural colloids, borehole specific bentonite colloid stability experiments and a fracture specific transport experiment. The activities concerning the laboratory experiments and background field measurements are described in this work; the other activities are ongoing or planned. The following conclusions were made: The bentonite colloid stability is strongly dependent on the groundwater ionic strength. Natural colloids are organic degradation products such as humic and fulvic acids, inorganic colloids (clay, calcite, iron hydroxide) and microbes. Microbes form few but large particles and their concentration increase with increasing organic carbon concentrations. The small organic colloids are present in very low concentrations in deep granitic groundwater. The concentrations can be rather high in shallow waters. The colloid concentration decreases with depth and salinity, since colloids are less stable in saline waters. The colloid content at Aespoe is less than 300 ppb. The colloid content at repository level is less than 50 ppb. The groundwater variability obtained in the boreholes reflects well the natural groundwater variability along the whole HRL tunnel.

Laaksoharju, Marcus [Geopoint AB, Stockholm (Sweden); Wold, Susanna [Royal Inst. of Tech., Stockholm (Sweden). School of Chemical Science and Engineering, Nuclear Chemistry] (eds.)

2005-12-15

 
 
 
 
221

The colloid investigations conducted at the Aespoe Hard Rock Laboratory during 2000-2004  

International Nuclear Information System (INIS)

In 2000, SKB decided to initiate an international colloid project at the Aespoe Hard Rock Laboratory in Sweden. The objectives of the colloid project are to: (i) study the role of bentonite as a colloid source, (ii) verify the background colloid concentration at Aespoe HRL and, (iii) investigate the potential for colloid formation/transport in natural groundwater concentrations. The experimental concepts for the colloid project are: laboratory experiments with bentonite, background field measurements of natural colloids, borehole specific bentonite colloid stability experiments and a fracture specific transport experiment. The activities concerning the laboratory experiments and background field measurements are described in this work; the other activities are ongoing or planned. The following conclusions were made: The bentonite colloid stability is strongly dependent on the groundwater ionic strength. Natural colloids are organic degradation products such as humic and fulvic acids, inorganic colloids (clay, calcite, iron hydroxide) and microbes. Microbes form few but large particles and their concentration increase with increasing organic carbon concentrations. The small organic colloids are present in very low concentrations in deep granitic groundwater. The concentrations can be rather high in shallow waters. The colloid concentration decreases with depth and salinity, since colloids are less stable in saline waters. The colloid content at Aespoe is less than 300 ppb. The colloid content at repository level is less than 50 ppb. The groundwater variability obtained in the boreholes reflects well the natural groundwater variability along the whole HRL tunnel

222

Experimental and theoretical investigation of high gradient acceleration  

Energy Technology Data Exchange (ETDEWEB)

This report contains a technical progress summary of the research conducted under the auspices of DOE Grant No. DE-FG0291ER-40648. Experimental and Theoretical Investigations of High Gradient Acceleration.'' This grant supports three research tasks: Task A consists of the design and fabrication of a 17GHz of photocathode gun, Task B supports the testing of high gradient acceleration using a 33GHz structure, and Task C comprises theoretical investigations, both in support of the experimental tasks and on critical physics issues for the development of high energy linear colliders. This report is organized as follows. The development of an rf gun design and research progress on the picosecond laser system is summarized in Sec. 2, the status of the studies of the LBL/Haimson high gradient structure, using a 50 MW free-electron laser is summarized in Sec. 3, and theoretical research progress is described in Sec. 4. Supporting material is contained in Appendices A-G.

Bekefi, G.; Chen, C.; Chen, S.; Danly, B.; Temkin, R.J.; Wurtele, J.S.

1992-02-01

223

Experimental investigation of turbulent mixing by Rayleigh-Taylor instability  

International Nuclear Information System (INIS)

A key feature of compressible turbulent mixing is the generation of vorticity via the ?px ?(1/?) term. This source of vorticity is also present in incompressible flows involving the mixing of fluids of different density, for example Rayleigh-Taylor unstable flows. This paper gives a summary of an experimental investigation of turbulent mixing at a plane boundary between two fluids, of densities ?1, and ?2. (?1 > ?2) due to Rayleigh-Taylor instability. The two fluids are near incompressible and mixing occurs when an approximately constant acceleration, g, is applied normal to the interface with direction from fluid 2 to fluid 1. Full details of the experimental programme are given in a set of three reports. Some of the earlier experiments are also described by Read. Previous experimental work and much of the theoretical research has concentrated on studying the growth of the instability from a single wavelength perturbation rather than turbulent mixing. Notable exceptions are published in the Russian literature. A related process, turbulent mixing induced by the passage of shock waves though an interface between fluids of different density is described by Andronov et al. The major purpose of the experiments described here was to study the evolution of the instability from small random perturbations where it is found that large and larger structures appear as time proceeds. A novel technique was used to provide the desired acceleration. The two fluids were enclosed in a rectangular tank, the lighter fluid 2 initially resting on top of the denser fluid 1. One or more rocket motors were then used to drive the tank vertically downwards. The aim of the experimental programme is to provide data for the calibration of a turbulence model used to predict mixing in real situations

224

Investigations of Solar Prominence Dynamics Using Laboratory Simulations  

International Nuclear Information System (INIS)

Laboratory experiments simulating many of the dynamical features of solar coronal loops have been carried out. These experiments manifest collimation, kinking, jet flows, and S-shapes. Diagnostics include high-speed photography and x-ray detectors. Two loops having opposite or the same magnetic helicity polarities have been merged and it is found that counter-helicity merging provides much greater x-ray emission. A non-MHD particle orbit instability has been discovered whereby ions going in the opposite direction of the current flow direction can be ejected from a magnetic flux tube.

225

Progress of investigations at the undeground research laboratory  

International Nuclear Information System (INIS)

Atomic Energy of Canada Limited (AECL) is constructing an Underground Research Laboratory (URL) in a previously undisturbed granitic pluton located near Lac du Bonnet, Manitoba as one of the major research projects within the Canadian Nuclear Fuel Waste Management Program. The research activities include site evaluation and underground experiment programs. The site evaluation program began in 1980 and is now in monitoring phase. The rock-mass and grounwater system have been characterized and modelled, and the actual response to URL excavation is being compared with the predictions. Underground experiments were conducted during shaft excavation, and some preliminary results are available

226

How important are the dermatophytes? A clinical and laboratory investigation.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Dermatophyte infections were established in 6.9% of 640 unselected dermatology outpatients attending two district general hospitals in Cumbria over a six-month period. A clinical diagnosis of ringworm was confirmed in the laboratory in 43.1% of hospital and in 21.8% of a smaller series of general practice patients. No result of similar surveys have been published before., Even in a major stock-rearing area such as this, domestic pets appear to be a more important source of infection than the ...

Davies, D. G.; Deighton, J.; Paterson, W. D.

1982-01-01

227

Environmental epidemiology applied to urban atmospheric pollution: a contribution from the Experimental Air Pollution Laboratory (LPAE  

Directory of Open Access Journals (Sweden)

Full Text Available Systematic investigation on the effects of human exposure to environmental pollution using scientific methodology only began in the 20th century as a consequence of several environmental accidents followed by an unexpected mortality increase above expected mortality and as a result of observational epidemiological and toxicological studies conducted on animals in developed countries. This article reports the experience of the Experimental Air Pollution Laboratory at the School of Medicine, University of São Paulo, concerning the respiratory system and pathophysiological mechanisms involved in responses to exposure to pollution using toxicological and experimental procedures, complemented by observational epidemiological studies conducted in the city of São Paulo. It also describes these epidemiological studies, pointing out that air pollution is harmful to public health, not only among susceptible groups but also in the general population, even when the concentration of pollutants is below the limits set by environmental legislation. The study provides valuable information to support the political and economic decision-making processes aimed at preserving the environment and enhancing quality of life.

André Paulo Afonso de

2000-01-01

228

Clinical and laboratory investigation of experimentaly infected broilers with CIAV  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Chicken infectious anemia (CIA) is widespread viral disease in countries with the intensive poultry industry. In susceptible birds CIAV causes anemia subcutaneous and intramuscular hemorrhages, lymphoid tissue atrophy immunosuppression, cachexia and increased mortality. Protection of progeny relies not only on age resistance but also on maternally delivered antibodies (Mabs) so possessing the information on level and persistence of Mabs is of great significance. In our study experimental infe...

Kapetanov Miloš C.; Orli? Dušan B.; Potkonjak Dubravka V.; Lazi? Sava M.

2004-01-01

229

Photoperiodic Treatments in Morning Glory: A Laboratory Investigation.  

Science.gov (United States)

The Japanese morning glory, a short-day plant, is an excellent specimen for studying photoperiodism. This article gives ideas for investigations including the effects of hormones, light quality, and temperature. Preparation of the seed is also discussed. (BB)

Madrazo, Gerry M., Jr.; Hounshell, Paul B.

1978-01-01

230

Students' Assessment of Interactive Distance Experimentation in Nuclear Reactor Physics Laboratory Education  

Science.gov (United States)

Laboratory experiments develop students' skills in dealing with laboratory instruments and physical processes with the objective of reinforcing the understanding of the investigated subject. In nuclear engineering, where research reactors play a vital role in the practical education of students, the high cost and long construction time of…

Malkawi, Salaheddin; Al-Araidah, Omar

2013-01-01

231

Laboratory Experimental System for Examination of Acoustic Emission Generated by Partial Discharges  

Directory of Open Access Journals (Sweden)

Full Text Available One of the major causes of transformer failures is dielectric breakdown. Partial discharges cause gradual insulation degradation thus partial discharge activity monitoring provides transformer state insight. This paper gives an overview of common methods for partial discharges detection and source location in transformers, with a special reference to the acoustic method as an noninvasive and interference resistant method suitable for application. For laboratory testing a laboratory experimental system for partial discharge diagnostics using acoustic emission measurement was developed.

I. M. Salom

2013-11-01

232

Laboratory astrophysics: Investigation of planetary and astrophysical maser emission  

Science.gov (United States)

This paper describes a model for cyclotron maser emission applicable to planetary auroral radio emission, the stars UV Ceti and CU Virginus, blazar jets and astrophysical shocks. These emissions may be attributed to energetic electrons moving into convergent magnetic fields that are typically found in association with dipole like planetary magnetospheres or shocks. It is found that magnetic compression leads to the formation of a velocity distribution having a horseshoe shape as a result of conservation of the electron magnetic moment. Under certain plasma conditions where the local electron plasma frequency ? pe is much less than the cyclotron frequency ? ce the distribution is found to be unstable to maser type radiation emission. We have established a laboratory-based facility that has verified many of the details of our original theoretical description and agrees well with numerical simulations. The experiment has demonstrated that the horseshoe distribution produces cyclotron emission at a frequency just below the local electron cyclotron frequency, with polarisation close to X-mode and propagating nearly perpendicularly to the electron beam motion. We discuss recent developments in the theory and simulation of the instability including addressing radiation escape problems, and relate these to the laboratory, space, and astrophysical observations. The experiments showed strong narrow band EM emissions at frequencies just below the cold-plasma cyclotron frequency as predicted by the theory. Measurements of the conversion efficiency, mode and spectral content were in close agreement with the predictions of numerical simulations undertaken using a particle-in-cell code and also with satellite observations confirming the horseshoe maser as an important emission mechanism in geophysical/astrophysical plasmas. In each case we address how the radiation can escape the plasma without suffering strong absorption at the second harmonic layer.

Bingham, R.; Speirs, D. C.; Kellett, B. J.; Vorgul, I.; McConville, S. L.; Cairns, R. A.; Cross, A. W.; Phelps, A. D. R.; Ronald, K.

233

Experimental investigation of the Richtmyer-Meshkov instability.  

Energy Technology Data Exchange (ETDEWEB)

The Richtmyer-Meshkov instability (RMI) is experimentally investigated using several different initial conditions and with a range of diagnostics. First, a broadband initial condition is created using a shear layer between helium+acetone and argon. The post-shocked turbulent mixing is investigated using planar laser induced fluorescence (PLIF). The signature of turbulent mixing is present in the appearance of an inertial range in the mole fraction energy spectrum and the isotropy of the late-time dissipation structures. The distribution of the mole fraction values does not appear to transition to a homogeneous mixture, and it is possible that this effect may be slow to develop for the RMI. Second, the influence of the RMI on the kinetic energy spectrum is investigated using particle image velocimetry (PIV). The influence of the perturbation is visible relatively far from the interface when compared to the energy spectrum of an initially flat interface. Closer to the perturbation, an increase in the energy spectrum with time is observed and is possibly due to a cascade of energy from the large length scales of the perturbation. Finally, the single mode perturbation growth rate is measured after reshock using a new high speed imaging technique. This technique produced highly time-resolved interface position measurements. Simultaneous measurements at the spike and bubble location are used to compute a perturbation growth rate history. The growth rates from several experiments are compared to a new reshock growth rate model.

Weber, Christopher R. (University of Wisconsin-Madison, Madison, WI)

2011-09-01

234

EXPERIMENTAL INVESTIGATION ON HIGH PERFORMANCE CONCRETE USING SILICAFUME AND FLYASH  

Directory of Open Access Journals (Sweden)

Full Text Available The purpose of this experimental investigation is to study the behaviour of High Performance Concrete (HPC. In this investigation HPC was manufactured by usual ingredients such as cement, fine aggregate, coarse aggregate, water and mineral admixtures such as Silica Fume (SF and Fly ash at various replacement levels and with Super Plasticizer. The water binder ratio (w/b adopted is 0.30. The concrete used in this investigation was proportioned to target a mean strength of 60 MPa. Specimens such as cubes, cylinders and prism beams were cast and tested for various mixes viz. Seven mixes M1 to M7 are cast with 0%, 5%, 7.5% and 10% replacement of SF and another set of specimens with 0%, 5%, 7.5% and 10% replacement of SF along with 10% constant replacement of Fly ash to study the mechanical properties such as compressive strength, split tensile strength and flexural strength at different ages of concrete such as 3, 7, 28, 56 and 90 days. The result shows that the optimum replacement of silica fume is 7.5%. Totally The specimens were tested in 1000 kN loading frame at 28 days. The results were tabulated.

Kannan Kannan

2012-09-01

235

Further laboratory and theoretical investigations of ammonium dinitramide  

Energy Technology Data Exchange (ETDEWEB)

Hydrogen and deuterated ammonium dinitramide have been vaporized under high vacuum and the IR matrix isolation spectra of the decomposition products obtained. Tentative vibration assignments have been made for HN(NO{sub 2}){sub 2} and DN(NO{sub 2}){sub 2} assuming a symmetrical non-planar structure in which the H or D is bonded to the central nitrogen atom. Other structures are also possible. Ab initio calculations have been made for the various structural isomers of hydrogen dinitramide. Vibration frequencies calculated for the hydrogenated and deuterated species are compared with the experimental values with the object of identifying the molecules` structure. (authors) 3 refs.

Tulis, A.J.; Snelson, A. [IIT Research Institut, Chicago (United States); Heberlein, C.; Patel, D.L. [U.S. Army Cecom RD et E Center, NVESD (United States)

1996-12-31

236

Experimental investigations in turbulent buoyant jets of sodium  

International Nuclear Information System (INIS)

Axisymmetric, turbulent buoyant jets are investigated in the sodium test section TEFLU. The character of the flow is divided into three regimes depending on the densimetric Froude number: the pure jet, the buoyant jet in the transition regime and the pure plume. By means of a temperature compensated Miniature Permanentmagnet Flowmeter Probe the mean velocity, mean temperature and intensity of temperature fluctuations are measured simultaneously at axial distances between 3 and 40 initial jet diameters from the orifice. The functional principle of the Miniature Permanentmagnet Flowmeter Probe which allows velocity measurements to be made in the presence of a temperature gradient is described in detail. For all three regimes both the decay laws of the quantities measured along the axis of the containment pipe and the radial profiles are indicated and discussed. With the help of the radial profiles of the mean quantities the axial development of the half-width radii and the axial development of the momentum, buoyancy and volume fluxes are calculated. In addition, the time history of the temperature fluctuations is recorded at several radial positions. The data are analysed according to characteristic values of statistical signal analysis such as minimum value, maximum value, skewness, flatness and according to characteristic functions such as probability density function, autopower spectrum density and autocorrelation function. The experimental results for the axisymmetric, turbulent buoyant jets of sodium are compared with experimental results from the literature and with fluids of molecular Prandtl numbers greater than or equal to 0.7. The basic differences betwen the experimental results obtained for water and for sodium are outlined. Statements are formulated which allow thermo- and fluiddynamic diffusion processes to be transferred from water to sodium. (orig.)

237

Experimental Investigation of MGB2 Switching with Magnetic Pulses  

Science.gov (United States)

Superconducting machines require DC current excitation in the rotor usually achieved using brushless exciters relying on solid state components for current rectification. The use of solid state components limits the amount of current allowable and imposes a large inductance in the rotor. MgB2 allows for "close to" superconducting splicing enabling development of large current rotors where solid state devices could be advantageously replaced by superconducting switches and used with a flux pump excitation system. For certain applications, such as a synchronous condenser, the dynamics of the excitation system is important as well as imposing fast switching and fast recovery. Switches driven by magnetic pulses are expected to exhibit a very limited temperature increase leading to fast recovery and also to contribute to very good system dynamics. This paper covers the experimental investigation of the response of MgB2 conductors subjected to magnetic pulses. The dependence of the resistance vs. J/Jc and operating temperature are discussed.

Ishmael, S. A.; Leveque, J.; Netter, D.; Meinke, R. B.; Masson, P. J.

2010-04-01

238

Experimental investigation of the trigger problem in magnetic reconnection  

International Nuclear Information System (INIS)

Magnetic reconnection releases magnetic energy not only in steady state, but also in time-dependent and often explosive events. Here, we investigate the trigger mechanism for this explosive release by using a toroidal experiment in the strong guide-field regime. We observe spontaneous reconnection events with exponentially growing reconnection rates, and we characterize the full 3D dynamics of these events using multiple internal probes. The reconnection is asymmetric: it begins at one toroidal location and propagates around in both directions. The spontaneous onset is facilitated by an interaction between the x-line current channel and a global mode, which appears in the electrostatic potential. It is this mode which breaks axisymmetry and enables a localized decrease in x-line current. We apply a simple model - which relies on ion polarization currents for current continuity - to reproduce the exponential growth and compute the growth rate. The result agrees well with the experimental growth rate.

239

Experimental investigation of a solar desiccant cooling installation  

Energy Technology Data Exchange (ETDEWEB)

Desiccant cooling is a technique based on evaporative cooling and air dehumidification using desiccant regenerated by thermal energy. It is particularly interesting when it is driven by waste or solar heat making this technique environmentally friendly. In this paper, an experimental investigation is carried on a desiccant air handling unit powered by vacuum-tube solar collectors. First, the components are studied under various operating conditions. Then overall performance of the installation is evaluated over a day for a moderately humid climate with regeneration solely by solar energy. In these conditions the overall efficiency of the solar installation is 0.55 while the thermodynamic coefficient of performance is 0.45 and the performance indicator based on the electrical consumption is 4.5. Finally, the impact of outside and regeneration conditions on the performance indicators is studied. (author)

Bourdoukan, P.; Wurtz, E. [LOCIE Laboratoire Optimisation de la Conception et Ingenierie de l' Environnement, Campus Scientifique Universite de Savoie, 73376 Le Bourget du Lac (France); Joubert, P. [LEPTIAB Laboratoire d' Etude des Phenomenes de Transfert et de l' Instantaneite Agro-Industrie et Batiment Pole Sciences et Technologies, Universite La Rochelle, Avenue Marillac 17000 La Rochelle (France)

2009-11-15

240

A review of experimental investigations on blast resistance of structures  

International Nuclear Information System (INIS)

Investigations on blast resistance of structures received a lot of importance during and after the second world war. In recent years, this has assumed importance, in view of the rise in terrorist attack, accidents and sabotage. Development of computers and sophisticated instrumentation has led to more accurate mathematical modelling of the blast and response phenomena and more accurate validation of the mathematical model by experiments, bringing the analysis of this class of problems within the reach of the theoretical analyst. An attempt is made to review some recent trends in modelling, instrumentation and experimental procedures adopted by researchers working in the area of blast resistance of structures. (author). 32 refs., 8 figs., 1 tab

 
 
 
 
241

Torsional Performance of Wind Turbine Blades : Part I: Experimental Investigation  

DEFF Research Database (Denmark)

The complete 3D static responses of two different eight meter long wind turbine blade sections were tested. To experimentally investigate the 3D response, an advanced 3D digital optical deformation measuring system (ARAMIS 2M and 4M) was applied in this work. This system measures the full-field displacements (ux, uy and uz) of the blade surface. A least squares algorithm was developed, which fits a plane through each deformed cross section, and defines a single set of displacements and rotations (three displacements and rotations) per cross section. This least squares algorithm was also used to accommodate problems with a flexible boundary condition by determining the displacements and rotations for a cross section near the boundary. These displacements and rotations are subtracted from all other cross sections along the blade and thereby making the blade section fully fixed at the chosen cross section near the boundary.

Branner, Kim; Berggreen, Christian

2007-01-01

242

Fibre reinforced composite dental bridge. Part I: Experimental investigation.  

Science.gov (United States)

This experimental investigation aims at revealing the mechanical behaviour and failure pattern of direct fibre-reinforced resin-bonded dental bridge with various designs. To evaluate the overall effects of some newly developed dental materials, in the experiment, genuine composite dental bridge specimens are prepared and tested. The ultimate load, stiffness and mode at the failure of the bridges are measured and compared with the design variations. A good agreement between test and some clinical observations is demonstrated. It is verified that the weakest region appears across the pontic-abutment interface in the composite bridges. This study suggests that the composite bridges reinforced by fibres and supported by adjacent teeth could be of a higher structural strength and stiffness; therefore would provide better clinical performances. PMID:15109860

Li, W; Swain, M V; Li, Q; Ironside, J; Steven, G P

2004-09-01

243

An experimental-differential investigation of cognitive complexity  

Directory of Open Access Journals (Sweden)

Full Text Available Cognitive complexity as defined by differential and experimental traditions was explored to investigate the theoretical advantage and utility of relational complexity (RC theory as a common framework for studying fluid cognitive functions. RC theory provides a domain general account of processing demand as a function of task complexity. In total, 142 participants completed two tasks in which RC was manipulated, and two tasks entailing manipulations of complexity derived from the differential psychology literature. A series of analyses indicated that, as expected, task manipulations influenced item difficulty. However, comparable changes in a psychometric index of complexity were not consistently observed. Active maintenance of information across multiple steps of the problem solving process, which entails strategic coordination of storage and processing that cannot be modelled under the RC framework was found to be an important component of cognitive complexity.

2009-12-01

244

Experimental in situ investigations of turbulence under high pressure.  

Science.gov (United States)

In tube injection systems applied in high-pressure processing of packed biomaterials and foods, the pressure-transmitting medium is injected into the vessel to increase the pressure up to 1000 MPa, generating a submerged liquid-free jet. The presence of a turbulent-free jet during the pressurization phase and its positive influence on the homogeneity of the product treatment has already been examined by computational fluid dynamics investigations. However, no experimental data have supported the existence and properties of turbulent flow under high-pressure (HP) conditions up to 400 MPa. This contribution presents the development of two experimental setups: HP-laser Doppler anemometry and HP-hot wire anemometry. For the first time the time-averaged velocity profiles of a free jet during pressurization up to 300 MPa at different Reynolds numbers (Re) have been obtained. In this article, the dependence of the velocity profiles on the Re is discussed in detail. Moreover, the relaminarization phenomenon of the turbulent pipe flow most likely caused by the compressibility effects and viscosity changes of the pressure-transmitting medium is examined. PMID:20233365

Song, Kwonyul; Al-Salaymeh, Ahmed; Jovanovic, Jovan; Rauh, Cornelia; Delgado, Antonio

2010-02-01

245

Experimental investigation of pyrolysis process of woody biomass mixture  

Science.gov (United States)

This paper describes an experimental investigation of pyrolysis of woody biomass mixture. The mixture consists of oak, beech, fir, cherry, walnut and linden wood chips with equal mass fractions. During the experiment, the sample mass inside the reactor was 10 g with a particle diameter of 5-10 mm. The sample in the reactor was heated in the temperature range of 24-650°C. Average sample heating rates in the reactor were 21, 30 and 54 °C/min. The sample mass before, during and after pyrolysis was determined using a digital scale. Experimental results of the sample mass change indicate that the highest yield of pyrolytic gas was achieved at the temperature slightly above 650°C and ranged from 77 to 85%, while char yield ranged from 15 to 23%. Heating rate has significant influence on the pyrolytic gas and char yields. It was determined that higher pyrolysis temperatures and heating rates induce higher yields of pyrolytic gas, while the char mass reduces. Condensation of pyrolytic gas at the end of the pyrolysis process at 650°C produced 2.4-2.72 g of liquid phase. The results obtained represent a starting basis for determining material and heat balance of pyrolysis process as well as woody biomass pyrolysis equipment.

Kosani?, Tijana R.; ?erani?, Mirjana B.; ?uri?, Slavko N.; Grkovi?, Vojin R.; Miloti?, Milan M.; Brankov, Saša D.

2014-06-01

246

An Experimental Investigation of Corium Jet Impingement on Structural Material  

Energy Technology Data Exchange (ETDEWEB)

During a severe accident in a nuclear power plant, the erosion of external structures of a reactor vessel by corium jet impingement owing to the failure of the reactor lower head is an important issue because the containment integrity can be seriously threatened. KAERI has proposed an experimental methodology and set up the VESTA (Verification of Ex-vessel corium STAbilization) facility to investigate the interaction of an oxidic jet with an oxidized steel (Fe{sub 2}O{sub 3}) structure containing a small amount of water and verify the existing ablation models. The oxidic jet impingement experiments on the oxidized steel structure containing a small amount of water content in crystalline hydrates were performed, and the ablation depth and rate were compared with the predictions by the existing models. The ablation of the structural material turned out to be governed by the jet convection, and the experimental results were predicted properly by the models. However, the models need to be improved by considering the transient effect of the heat transfer for better predictions, which is left as a future work.

An, Sang Mo; Ha, Kwang Soon; Min, Beong Tae; Hong, Seong Ho; Kim, Hwan Yeol [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2013-10-15

247

An Experimental Investigation of Corium Jet Impingement on Structural Material  

International Nuclear Information System (INIS)

During a severe accident in a nuclear power plant, the erosion of external structures of a reactor vessel by corium jet impingement owing to the failure of the reactor lower head is an important issue because the containment integrity can be seriously threatened. KAERI has proposed an experimental methodology and set up the VESTA (Verification of Ex-vessel corium STAbilization) facility to investigate the interaction of an oxidic jet with an oxidized steel (Fe2O3) structure containing a small amount of water and verify the existing ablation models. The oxidic jet impingement experiments on the oxidized steel structure containing a small amount of water content in crystalline hydrates were performed, and the ablation depth and rate were compared with the predictions by the existing models. The ablation of the structural material turned out to be governed by the jet convection, and the experimental results were predicted properly by the models. However, the models need to be improved by considering the transient effect of the heat transfer for better predictions, which is left as a future work

248

Experimental Investigation of Turbulent Flow in Transition Duct  

Directory of Open Access Journals (Sweden)

Full Text Available An experimental study was conducted to investigate turbulent flow through from rectangular cross-sectional area to rectangular transition duct. Three kinds of channels with different length, side angle and geometrical dimensions were designed and then flow characteristic of them were all tested. The transition duct have different inlet and outlet cross-sectional areas, outlet section is double than inlet sectional area. Measurements were made at several station along the channel and at various flow-rates, Reynolds numbers ranging from 2.105 to 6.105, in which the two–dimensional mean, local velocity and pressure were measured at the x/l = 0.20, 0.40, 0.60, 0.80, 1.00 ratio, inlet by using hot wire anemometer. Based on experimental results, different flow characteristics were obtained. According to mean and local velocity and pressure drop values, each section point of the transition duct showed various values. Friction coefficient was lowered with increasing pipe length and increasing Reynolds number. Cross flows was shown in the short pipe along length at the low Reynolds.

Hasan GÜL

2012-12-01

249

Thermal mirror spectrometry: An experimental investigation of optical glasses  

Science.gov (United States)

The Thermal mirror technique relies on measuring laser-induced nanoscale surface deformation of a solid sample. The amplitude of the effect is directly dependent on the optical absorption and linear thermal expansion coefficients, and the time evolution depends on the heat diffusion properties of the sample. Measurement of transient signals provide direct access to thermal, optical and mechanical properties of the material. The theoretical models describing this effect can be formulated for very low optical absorbing and for absorbing materials. In addition, the theories describing the effect apply for semi-infinite and finite samples. In this work, we apply the Thermal mirror technique to measure physical properties of optical glasses. The semi-infinite and finite models are used to investigate very low optical absorbing glasses. The thickness limit for which the semi-infinite model retrieves the correct values of the thermal diffusivity and amplitude of the transient is obtained using the finite description. This procedure is also employed on absorbing glasses, and the semi-infinite Beer-Lambert law model is used to analyze the experimental data. The experimental data show the need to use the finite model for samples with very low bulk absorption coefficients and thicknesses L 1.0 mm in this case. In addition, the physical properties of the samples were calculated and absolute values derived.

Zanuto, V. S.; Herculano, L. S.; Baesso, M. L.; Lukasievicz, G. V. B.; Jacinto, C.; Malacarne, L. C.; Astrath, N. G. C.

2013-03-01

250

Experimental Investigation on the Viscosity of Nano fluids  

International Nuclear Information System (INIS)

In this study, the effect of adding SiO2 nanoparticles on the viscosity of base fluid is investigated experimentally. Base fluids are chosen among common heat transfer fluids such as ethylene glycol, transformer oil and water. In addition different volume percentages of ethylene glycol in water are used as ethylene glycol-water solution. In every base fluid different volume fractions of SiO2 nanoparticles is added. It is shown that the viscosity of solution enhance by adding nanoparticles. The effect of cooling and heating process on the viscosity of nano fluid is also discussed. The presented data show that as the temperature increases the viscosity of base fluid and nano fluid decrease. It is also revealed that there are very little differences between the viscosity of nano fluid in a specific temperature at cooling and heating cycles. According to the experimental results new correlations for predicting the viscosity of nano fluids is presented. These correlations relate the viscosity of nano fluid to the particle volume fraction and temperature.

251

Experimental and theoretical investigation of anaerobic fluidized bed biofilm reactors  

Directory of Open Access Journals (Sweden)

Full Text Available This work presents an experimental and theoretical investigation of anaerobic fluidized bed reactors (AFBRs. The bioreactors are modeled as dynamic three-phase systems. Biochemical transformations are assumed to occur only in the fluidized bed zone. The biofilm process model is coupled to the system hydrodynamic model through the biofilm detachment rate; which is assumed to be a first-order function of the energy dissipation parameter and a second order function of biofilm thickness. Non-active biomass is considered to be particulate material subject to hydrolysis. The model includes the anaerobic conversion for complex substrate degradation and kinetic parameters selected from the literature. The experimental set-up consisted of two mesophilic (36±1ºC lab-scale AFBRs (R1 and R2 loaded with sand as inert support for biofilm development. The reactor start-up policy was based on gradual increments in the organic loading rate (OLR, over a four month period. Step-type disturbances were applied on the inlet (glucose and acetic acid substrate concentration (chemical oxygen demand (COD from 0.85 to 2.66 g L-1 and on the feed flow rate (from 3.2 up to 6.0 L d-1 considering the maximum efficiency as the reactor loading rate switching. The predicted and measured responses of the total and soluble COD, volatile fatty acid (VFA concentrations, biogas production rate and pH were investigated. Regarding hydrodynamic and fluidization aspects, variations of the bed expansion due to disturbances in the inlet flow rate and the biofilm growth were measured. As rate coefficients for the biofilm detachment model, empirical values of 3.73?10(4 and 0.75?10(4 s² kg-1 m-1 for R1 and R2, respectively, were estimated.

M. Fuentes

2009-09-01

252

Experimental and theoretical investigation of anaerobic fluidized bed biofilm reactors  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english This work presents an experimental and theoretical investigation of anaerobic fluidized bed reactors (AFBRs). The bioreactors are modeled as dynamic three-phase systems. Biochemical transformations are assumed to occur only in the fluidized bed zone. The biofilm process model is coupled to the syste [...] m hydrodynamic model through the biofilm detachment rate; which is assumed to be a first-order function of the energy dissipation parameter and a second order function of biofilm thickness. Non-active biomass is considered to be particulate material subject to hydrolysis. The model includes the anaerobic conversion for complex substrate degradation and kinetic parameters selected from the literature. The experimental set-up consisted of two mesophilic (36±1ºC) lab-scale AFBRs (R1 and R2) loaded with sand as inert support for biofilm development. The reactor start-up policy was based on gradual increments in the organic loading rate (OLR), over a four month period. Step-type disturbances were applied on the inlet (glucose and acetic acid) substrate concentration (chemical oxygen demand (COD) from 0.85 to 2.66 g L-1) and on the feed flow rate (from 3.2 up to 6.0 L d-1) considering the maximum efficiency as the reactor loading rate switching. The predicted and measured responses of the total and soluble COD, volatile fatty acid (VFA) concentrations, biogas production rate and pH were investigated. Regarding hydrodynamic and fluidization aspects, variations of the bed expansion due to disturbances in the inlet flow rate and the biofilm growth were measured. As rate coefficients for the biofilm detachment model, empirical values of 3.73?10(4) and 0.75?10(4) s² kg-1 m-1 for R1 and R2, respectively, were estimated.

M., Fuentes; M. C., Mussati; P. A., Aguirre; N. J., Scenna.

2009-09-01

253

Nonlinear dynamics of a MEMS resonator: Theoretical and experimental investigation  

Science.gov (United States)

In this study we present a theoretical and experimental investigation of a microelectromechanical system (MEMS). The device is constituted of a clamped-clamped polysilicon microbeam electrostatically and electrodynamically actuated. The microbeam has a slightly curled up configuration, which is an imperfection commonly encountered as a consequence of the microfabrication process. Using a laser Doppler vibrometer, many experimental frequency sweeps are conducted in a neighborhood of the first symmetric natural frequency. To simulate the dynamics, we derive a single-mode reduced-order model. Extensive numerical investigations are performed, based on frequency response diagrams and behavior charts. The overall scenario of the response is explored, when both the frequency and the electrodynamic voltage are varying. This analysis is able to provide a very good matching with the experiments. Nevertheless, the theoretical predictions are not completely fulfilled in some aspects. In particular, the range of existence of each attractor is smaller in practice than in the simulations. This is because the theoretical curves represent the ideal limit case where disturbances are absent, which never occurs in experiments and practice. To overcome this drawback and extend the results to the practical case where disturbances exist, we develop a dynamical integrity analysis. After introducing dynamical integrity concepts, we perform integrity profiles and integrity charts. They are able to describe if each attractor is robust enough to tolerate the disturbances. They detect the parameter range where each branch can be reliably observed in practice and where, instead, becomes vulnerable, i.e., depending on the expected disturbances, they provide valuable information to operate the device in safe conditions according to the desired outcome.

Ruzziconi, Laura; Bataineh, Ahmad M.; Younis, Mohammad I.; Cui, Weili; Lenci, Stefano

2012-11-01

254

An Investigation into the Effectiveness of Problem-Based Learning in a Physical Chemistry Laboratory Course  

Science.gov (United States)

The aim of this study was to investigate the effectiveness of a problem-based learning (PBL) approach in a physical chemistry laboratory course. The parameters investigated were students' attitudes towards a chemistry laboratory course, scientific process skills of students and their academic achievement. The design of the study was one group…

Gurses, Ahmet; Acikyildiz, Metin; Dogar, Cetin; Sozbilir, Mustafa

2007-01-01

255

Laboratory investigation of shock waves in a weakly magnetized plasma  

International Nuclear Information System (INIS)

Experimental measurements of the structure of collision dominated shock waves propagating into a weakly magnetized hydrogen plasma are described. The initial magnetic field is varied in the range 0.035T to zero with corresponding Alfven Mach number in the range 2.5 to infinity and sonic Mach number in the range 6.5 to 2. At the lower field values the influence of the magnetic field on the shock dissipation is negligible. The measured shock structure is in general agreement with theoretical non-magnetic shock structure based on a two fluid model with classical transport coefficients in that (i) a precursor thermal wave exists ahead of the velocity transition, (ii) the velocity transition occurs in a distance approximately twice the ion mean free path in the post-shock region, (iii) the electron heating within the shock is comparable with the ion heating. (author)

256

Experimental investigations on the heat transfer behaviour of near-surface flowed surfaces; Experimentelle Untersuchungen zum Waermetransportverhalten oberflaechennaher durchstroemter Boeden  

Energy Technology Data Exchange (ETDEWEB)

Since May 2010, the research project 'Energy-optimized construction - Experimental investigations to the verification of a finite element multi-phase model for the heat transfer behaviour in the subsurface' was sponsored by the Federal Ministry of Economics and Technology (Berlin, Federal Republic of Germany). This research contains experimental geothermal investigations from the Institute for Materials and Mechanics in the Building Industry at the Technical University of Darmstadt (Federal Republic of Germany). In addition to extensive field testings, a laboratory test rig for the investigation of the geothermal heat flow and heat transfer has been developed in conjunction with the Institute for Applied Geosciences at the Technical University of Darmstadt. Using this test rig, currently thermal conductivity experiments were performed at different filtration rates, thermal load cases and installation configurations. A large portion of the experimental program at the calibrated equipment has been completed. The authors of the contribution under consideration report on the results of laboratory tests.

Huber, Heiko; Arslan, Ulvi [Technische Univ. Darmstadt (Germany). Inst. fuer Werkstoffe und Mechanik im Bauwesen; Stegner, Johannes; Sass, Ingo [Technische Univ. Darmstadt (Germany). Inst. fuer Angewandte Geowissenschaften

2011-10-24

257

LABEXNET: un Laboratorio de Economía Experimental en Internet. [LABEXNET: Internet-based laboratory for experimental Economics  

Directory of Open Access Journals (Sweden)

Full Text Available Experimental Economists have designed over the years a wide range of scientific experiments that can be usefully employed nowadays as teaching aids. The interactive and participatory nature of such experiments serves as a motivation to students, stimulates their own thinking, and enhances their insights into the forces that drive economic markets: the aggregate interactions of economic agents within a market institution. Economic classroom games have been recognised as useful teaching tools for decades, and they have often produced surprising results and better understanding of market dynamics and institutions. Nowadays the new information technologies can be brought into play to conduct and analyse experimental games in unprecedented ways: using Internet-based tools, the design, execution and analysis of classroom games can be made considerably easier than traditionally. In this paper we introduce LABEXNET, a program designed to conduct Internet-based economic classroom games. LABEXNET is freely available to the academic community.. La Economía Experimental ha desarrollado diferentes experimentos que pueden ser aprovechados como una actividad docente en la enseñanza de la Economía. Su naturaleza activa y participativa motiva a los alumnos y estimula la reflexión y la mejor comprensión de algunos fenómenos económicos como el funcionamiento de los mercados, donde los resultados individuales dependen del conjunto de las decisiones de los agentes y de sus interacciones. Los experimentos económicos tienen ya una larga tradición, y han proporcionado resultados espectaculares y conclusiones ampliamente admitidas sobre la dinámica de mercados y el efecto de las instituciones económicas. Las nuevas tecnologías facilitan la realización y el análisis de estos experimentos. En este artículo presentamos LABEXNET, un programa informático para la realización de experimentos económicos por Internet puesto a libre disposición de la comunidad académica..

Galán Ordax, José Manuel

2007-06-01

258

Experimental investigation of the cell survival in dose cold spot.  

Science.gov (United States)

The aim of this work was to investigate the impact of intercellular contact during radiation exposure on cell survival in regions of reduced dose. Methods. The PC3 human prostate adenocarcinoma cell line was irradiated using a 6 MV x-ray beam to assess clonogenic cell deaths with the specific aim to investigate cell survival in a dose cold spot. Radiation-induced cell survival in a 20% lower dose region, compared to that of cells receiving 100% of the prescribed dose (2 Gy), was assessed for experimental set-ups when under-irradiated cells were either in direct contact with cells receiving 2 Gy or irradiated separately. In addition, the results were compared against non-irradiated controls. Results. A significant (p spot of 20% lower dose) compared to non-irradiated cells. However, in the experiment in which the entire flask was exposed to only 80% of the prescribed dose, the mean difference in cell survival compared to non-irradiated control was not significant (p > 0.05). This was contrary to a significant decrease (p reduction (p spot region was significantly lower when under-irradiated cells were in contact with the cells receiving 100% of the prescribed dose compared to survival of cells under-irradiated by the same amount of radiation but treated separately to cells receiving 100% dose. PMID:23617540

Sjostedt, Svetlana; Bezak, Eva; Marcu, Loredana

2014-01-01

259

Theoretical and experimental investigation of compaction bands in porous rock  

Science.gov (United States)

Field investigators have recently discovered thin, tabular zones of pure compressional deformation that they called compaction bands. These bands were found in association with shear bands and were postulated to be genetically related to them. At the laboratory scale, compaction bands have been noticed in association with boreholes and preexisting, artificial shear cracks subjected to compressive stress fields. Natural compaction bands are noticeable in outcrops because of their resistance to weathering; however, they may be more difficult to discern on freshly cut rock surfaces such as drill core or borehole walls. Because of the much reduced porosity in the compaction bands, these structures are potentially important as permeability barriers in reservoirs and aquifers in porous rocks. For bands associated with boreholes, the crushed material can be washed into the borehole contributing to sand production and possibly altering the stability of the borehole. This paper examines a theoretical framework that explains these features as a constitutive instability leading to localized compaction in a way completely analogous to shear strain localization. Conventional triaxial experiments on Castlegate sandstone resulted in compaction bands. In addition, thick deformation bands having normals at low angles to the maximum compression are present in some specimens.

Olsson, William A.

1999-04-01

260

Theoretical and experimental investigation of compaction bands in porous rock  

Energy Technology Data Exchange (ETDEWEB)

Field investigators have recently discovered thin, tabular zones of pure compressional deformation that they called compaction bands. These bands were found in association with shear bands and were postulated to be genetically related to them. At the laboratory scale, compaction bands have been noticed in association with boreholes and preexisting, artificial shear cracks subjected to compressive stress fields. Natural compaction bands are noticeable in outcrops because of their resistance to weathering; however, they may be more difficult to discern on freshly cut rock surfaces such as drill core or borehole walls. Because of the much reduced porosity in the compaction bands, these structures are potentially important as permeability barriers in reservoirs and aquifers in porous rocks. For bands associated with boreholes, the crushed material can be washed into the borehole contributing to sand production and possibly altering the stability of the borehole. This paper examines a theoretical framework that explains these features as a constitutive instability leading to localized compaction in a way completely analogous to shear strain localization. Conventional triaxial experiments on Castlegate sandstone resulted in compaction bands. In addition, thick deformation bands having normals at low angles to the maximum compression are present in some specimens. {copyright} 1999 American Geophysical Union

Olsson, W.A. [Sandia National Laboratories, Albuquerque, New Mexico (United States)

1999-04-01

 
 
 
 
261

Experimental investigations on airborne gravimetry based on compressed sensing.  

Science.gov (United States)

Gravity surveys are an important research topic in geophysics and geodynamics. This paper investigates a method for high accuracy large scale gravity anomaly data reconstruction. Based on the airborne gravimetry technology, a flight test was carried out in China with the strap-down airborne gravimeter (SGA-WZ) developed by the Laboratory of Inertial Technology of the National University of Defense Technology. Taking into account the sparsity of airborne gravimetry by the discrete Fourier transform (DFT), this paper proposes a method for gravity anomaly data reconstruction using the theory of compressed sensing (CS). The gravity anomaly data reconstruction is an ill-posed inverse problem, which can be transformed into a sparse optimization problem. This paper uses the zero-norm as the objective function and presents a greedy algorithm called Orthogonal Matching Pursuit (OMP) to solve the corresponding minimization problem. The test results have revealed that the compressed sampling rate is approximately 14%, the standard deviation of the reconstruction error by OMP is 0.03 mGal and the signal-to-noise ratio (SNR) is 56.48 dB. In contrast, the standard deviation of the reconstruction error by the existing nearest-interpolation method (NIPM) is 0.15 mGal and the SNR is 42.29 dB. These results have shown that the OMP algorithm can reconstruct the gravity anomaly data with higher accuracy and fewer measurements. PMID:24647125

Yang, Yapeng; Wu, Meiping; Wang, Jinling; Zhang, Kaidong; Cao, Juliang; Cai, Shaokun

2014-01-01

262

Experimental investigation of the acceleration of deflagration in wake flow  

International Nuclear Information System (INIS)

In gas cloud explosions, turbulence is produced by the flow-field induced by the combustion process. But turbulence can also be produced by an initial flow field, due to atmospheric wind or technical devices. This turbulence may lead to an increased rate of chemical reaction, inducing high pressure levels. The influence of an initial flow field must be taken into account, in connection with safety aspects of nuclear power plants. The reported laboratory-scale experiments were designed to investigate the influence of a flow field, present at the moment of ignition inside a partially-confined hydrocarbon-air cloud. These experiments used a flow channel capable of producing an unsteady flow-field of combustible gas independently of the combustion process itself. The parameters which varied in these tests are: initial flow velocity, gas-mixture composition and geometry. The tests were carried out with stochiometric ethylene-air and propane-air mixtures. The measured quantities are: pressure time history inside the test section. CH-radical radiation. High-speed photographs were also taken. The results show that initial flow speed and reactivity of the mixture have a strong influence on the maximum overpressure and duration of the positive pressure phase, but quenching effects may become important for high flow velocities and mixtures of low reactivity

263

Theoretical and Experimental Investigation of Liquid Metal MHD Power Generation  

International Nuclear Information System (INIS)

Liquid metal magnetohydrodynamic power generation for space is studied. Closed- loop circulation of liquid metal without moving mechanical parts, and generation of electric power from the circulating metal, have been investigated analytically and experimentally, and the attainable cycle efficiencies have been calculated. Recent literature has pointed out the possibility of efficient a.c. generators with liquid metal as the working fluid, and this type of generator is under study. Analysis indicates that efficiencies up to 65% are attainable in a travelling-wave induction generator at the available liquid metal velocities of 100-200 m/sec, provided the generator has a length/gap ratio of no more than 50 for low friction loss, has an electrical length of no more than three wavelengths for low winding loss, and has end-effect compensation for cancelling finite-length effects in the power-generating region. The analysis leading to these conclusions is presented. The type of end-effect correction being studied is the ''compensating-pole'' technique in which an oscillating magnetic field is applied to the fluid entering and leaving the generator to make the flux linkages within the generator the same as those in a rotating or ''infinite'' generator. An experimental one-wavelength generator employing compensating poles has been fabricated, and empty-channel magnetic field measurements have been completed in preparation for tests with NaK. Two types of field measurements were made: d.c. measurements to determine the field profile as a function of phase angle and a.c. measurements to investigate the synchronization of the compensating poles with the travelling wave. The d.c. results showed that the flux linkages in the power generating region can be held close to those in a rotating machine, and the a.c. results showed that the compensating poles can be accurately synchronized with the travelling wave through transformer coupling. The component efficiencies from the analyses and experiments were combined to predict the cycle efficiencies possible in space applications. The calculations included the different liquid MHD cycles and working fluids that have been proposed in the literature, and these cycles are reviewed and compared. A possible limitation on lifetime at the 1100-1500°K temperatures needed for a space power plant is erosion by the high velocity liquid metal, and this problem is being investigated in a 70 m/sec lithium loop. (author)

264

Overview of Experimental Investigations for Ares I Launch Vehicle Development  

Science.gov (United States)

Another concern for the vehicle during its design trajectory was the separation of the first stage solid rocket booster from the upper stage component after it had depleted its solid fuel propellant. There has been some concern about the interstage of the first stage from clearing the nozzle of the J2-X engine. A detailed separation aerodynamic wind tunnel investigation was conducted in the AEDC VKF Tunnel A to help to investigate the interaction aerodynamic effects5. A comparison of the separation plane details between the Ares I architecture and the Ares I-X demonstration flight architecture is shown in figure 12. The Ares I design requires a more complex separation sequence and requires better control in order to avoid contact with the nozzle of the upper stage engine. The interstage, which houses the J2-X engine for the Ares I vehicle, must be able to separate cleanly to avoid contact of the J2-X engine. There is only about approximately 18 inches of buffer inside the interstage on each size of the nozzle so this is a challenging controlled separation event. This complex experimental investigation required two separate Ares I models (upper stage and first stage with interstage attached) with independent strain gauge balances installed in each model. It also required the Captive Trajectory System (CTS) that was needed to precisely locate the components in space relative to each other to fill out the planned test matrix. The model setup in the AEDC VKF Tunnel A is shown in figure 13. The CTS remotely positioned the first stage at the required x, y, and z positions and was able to provide interactions within 0.2" of the upper stage. A sample of the axial force on the first stage booster is shown in figure 14. These results, as a function of separation distance between the two stages, are compared to pre-test CFD results. Since this is a very challenging, highly unsteady flow field for CFD to correctly model, the experimental results have been utilized by GN&C discipline to more accurately represent the interaction aerodynamics. In addition to the integrated forces and moments obtained from the test, flow visualization data was obtained from this test in the form of Schlieren photographs, as shown in figure 15, which show the shock structure and interaction effects after the two stages separate during flight. This separation test was crucial in the successful flight test of the Ares I-X vehicle and provided the GN&C discipline with the unpowered proximity aerodynamic effect for a separation of the Ares I vehicle.

Tomek, William G.; Erickson, Gary E.; Pinier, Jeremy T.; Hanke, Jeremy L.

2011-01-01

265

Clinical and laboratory investigation of experimentaly infected broilers with CIAV  

Directory of Open Access Journals (Sweden)

Full Text Available Chicken infectious anemia (CIA is widespread viral disease in countries with the intensive poultry industry. In susceptible birds CIAV causes anemia subcutaneous and intramuscular hemorrhages, lymphoid tissue atrophy immunosuppression, cachexia and increased mortality. Protection of progeny relies not only on age resistance but also on maternally delivered antibodies (Mabs so possessing the information on level and persistence of Mabs is of great significance. In our study experimental infection with CIAV was performed on one and seven days old broiler chickens from naturally infected parent flock during the rearing period. In infected birds, clinical signs hematological findings and humoral immune response were examined. After euthanasia, we looked for specific pathomorphological and histopathological changes that indicate the presence of CIAV infection. In all one and seven days old chickens maternally derived antibodies were established. No clinical signs of CIA were observed, hematological findings showed no deviation from referent values, and there were no specific pathomorphological and histopathological changes at postmortem examination. According to previous knowledge, only serological negative flock if infected in time of laying represent risk for vertical transmission to progeny where typical disease with mortality will appear. The absence of Mabs in one day old chickens is critical point in break of disease. Typical clinical picture in day old chickens rises only when vertical transmission occurs.

Kapetanov Miloš C.

2004-01-01

266

Air/water oxydesulfurization of coal: laboratory investigation  

Energy Technology Data Exchange (ETDEWEB)

Air/water oxidative desulfurization has been demonstrated in autoclave experiments at the Pittsburgh Energy Technology Center for various coals representative of the major US coal basins. This experimentation has shown that the reaction proceeds effectively for pulverized coals at temperatures of 150 to 200/sup 0/C with air at a total system pressure of 500 to 1500 psig. Above 200/sup 0/C, the loss of coal and product heating value increases due to oxidative consumption of carbon and hydrogen. The pyritic sulfur solubilization reactions are typically complete (95 percent removal) within 15 to 40 minutes at temperature; however, significant apparent organic sulfur removal requires residence times of up to 60 minutes at the higher temperatures. The principal products of the reaction are sulfuric acid, which can be neutralized with limestone, and iron oxide. Under certain conditions, especially for high pyritic sulfur coals, the precipitation of sulfur-containing compounds from the products of the pyrite reaction may cause anomalous variations in the sulfur form data. The influence of various parameters on the efficiency of sulfur removal from coal by air/water oxydesulfurization has been studied.

Warzinski, R. P.; Friedman, S.; Ruether, J. A.; LaCount, R. B.

1980-08-01

267

Combined Experimental and Numerical Investigations into Laser Propulsion Engineering Physics  

Science.gov (United States)

The RPI pulsed Laser Propulsion (LP) research effort focuses on the future application of launching nano- and micro-satellites (1-10 kg payloads) into Low Earth Orbit (LEO), using a remote Ground Based Laser (GBL) power station to supply the required energy for flight. This research program includes both experimental and numerical studies investigating the propulsive performance of several engine geometries (constituting a lightcraft family). Using the Lumonics twin K-922m TEA pulsed laser system, axial and lateral thrust, C m, Isp, and ? measurements were made for these engine geometries, examining the effects of several critical factors including: engine orientation (e.g. lateral and angular offset), laser pulse energy, pulse repetition frequency, pulse duration, propellant type, and engine size-scaling effects. Investigation into the origins of lateral "beam riding" forces was of particular interest. Lateral impulse measurements and high speed Schlieren photography were utilized to provide an understanding of laser beam-riding/propulsive physics. The acquired lightcraft database was used to further develop an existing 7-Degree Of Freedom (DOF) flight dynamics model extensively calibrated against 16 actual trajectories of small scale model lightcraft flown at White Sands Missile Range, NM on a 10 kW pulsed CO2 laser called PLVTS. The full system 7-DOF model is comprised of updated individual aerodynamics, engine, laser beam propagation, variable vehicle inertia, reaction controls system, and dynamics models, integrated to represent all major phenomena in a consistent framework. This flight dynamics model and associated 7-DOF code provide a physics-based predictive tool for basic research investigations into laser launched lightcraft for suborbital and orbital missions. Simulations were performed to demonstrate the flight capabilities of each engine geometry using the updated lightcraft propulsion database, the results of which further demonstrate that autonomous beam riding capability is an essential component for a stable launch to orbit and the future of LP.

Kenoyer, David Adam

268

Laboratory investigation of platelet function in patients with thalassaemia.  

Science.gov (United States)

The aim of this study was to investigate platelet function in patients with thalassaemia and to detect any relation to chelation treatment (deferasirox or deferiprone/deferiprone plus desferioxamine). Thirty-three transfusion-dependent patients with thalassaemia were included. The investigation consisted of aggregation testing of platelet-rich plasma by light transmission aggregometry (LTA) with the use of 5 agonists as well as the global test of haemostasis by means of the PFA-100 platelet function analyser. In 66.67% of the patients, there was reduced LTA to at least one agonist and in 18.18% there was reduced LTA to two or more agonists. The PFA-100 test was prolonged in 60.6% of the cases. An abnormal LTA and a prolonged PFA-100 time were recorded in 33.3% of the patients and 27.4% had a normal aggregation and PFA-100 test. No correlation between chelation regimen and either LTA or PFA-100 test was found. The abnormal LTA can be explained either by the release of ADP from the haemolysed red blood cells, which leads to defective platelet aggregation, or by the presence of two platelet populations. An in vitro effect without an in vivo impact could be an alternative explanation. In patients with thalassaemia, the reduced LTA and the prolonged PFA-100 closure time could be an in vitro effect and has a close correlation to the bleeding phenotype of each patient. PMID:24434633

Theodoridou, S; Economou, M; Vyzantiadis, T-A; Teli, A; Vlachaki, E; Neokleous, N; Kargioti, A; Vakalopoulou, S; Garypidou, V; Gombakis, N; Papachristou, F

2014-01-01

269

Experimental investigation of hot electrons inside cavity target  

International Nuclear Information System (INIS)

In the interaction of intense laser-plasma, hot electrons, which can preheat the core of the fuel and lower the compression efficiency, are produced by collective processes such as stimulated Raman Scattering (SRS), resonance absorption (RA), two plasma decay (TPD) and ion acoustic decay (IAD). It is very important to study hot electrons experimentally and theoretically. The spectrum and total energy of hard X-rays outside the cavity targets have been measured for many years. In order to correct theoretical model and improve accuracy of calculating the total energy of hot electrons in cavities, it is urgent to identify the traveling direction of hot electrons and the regions of hard X-rays generation. In the experiment reported, specific cavities was designed to investigate the angular distribution of hot electrons in cavity and the region of hard X-ray generation. Experiments were conduced on Shengguang high power laser facility. The cavity target was irradiated by one beam laser (? = 1.06 ?m, EL = 450?550 J, ?? 0.8 ns, IL ?1015 W·cm-2). A ten channel filter fluorescence spectrometer and an array of separate GaAs photoconductor were used to measure the spectra, angular distribution, and total energy of hard X-rays, and the energy of stimulated Raman scattering light was also measured for comparison. From the specific structure of cavities and the experimental results, the following two main results were inferred: (1) Most of the hot electrons in cavity are inclined to travel along the direction of laser wave vector, not isotropically. (2) Hard X-rays were mainly produced by Bremsstrahlung effect of hot electrons' collision with gold cavity wall

270

Calculation and experimental investigation of multi-component ceramic systems  

International Nuclear Information System (INIS)

This work shows a way to combine thermodynamic calculations and experiments in order to get useful information on the constitution of metal/non-metal systems. Many data from literature are critically evaluated and used as a basis for experiments and calculations. The following multi-component systems are treated: 1. Multi-component systems of 'ceramic' materials with partially metallic bonding (carbides, nitrides, oxides, borides, carbonitrides, borocarbides, oxinitrides of the 4-8th transition group metals) 2. multi-component systems of non-metallic materials with dominant covalent bonding (SiC, Si3N4, SiB6, BN, Al4C3, Be2C) 3. multi-component systems of non-metallic materials with dominant heteropolar bonding (Al2O3, TiO2, BeO, SiO2, ZrO2). The interactions between 1. and 2., 2. and 3., 1. and 3. are also considered. The latest commercially available programmes for the calculation of thermodynamical equilibria and phase diagrams are evaluated and compared considering their facilities and limits. New phase diagrams are presented for many presently unknown multi-component systems; partly known systems are completed on the basis of selected thermodynamic data. The calculations are verified by experimental investigations (metallurgical and powder technology methods). Altogether 690 systems are evaluated, 126 are calculated for the first time and 52 systems are experimentally verified. New data for 60 ternary phases are elaborated by estimating the data limits for the Gibbs energy values. A synthesis of critical evaluation of literature, calculations and experiments leads to new important information about equilibria and reaction behaviour in multi-component systems. This information is necessary to develop new stable and metastable materials. (orig./MM)

271

Experimental investigation on compaction properties of sandy soils  

International Nuclear Information System (INIS)

In this research, an effort has been made to develop a correlation between standard and modified proctor compaction test parameters, i.e., maximum dry unit weight (gamma dmax) and optimum moisture content (OMC) of sandy soils. Standard and modified proctor along with classification tests were carried out on hundred and twenty sandy soil samples with different grain size distributions. Based on the test results, the soil samples were classified into various groups of medium to fine sand with non-plastic fines up to 45%. Regression analyses were performed on the experimental data and correlations were proposed to express modified Proctor parameters (gamma dmod and OMC mod) in term of standard Proctor test parameters (gamma dstd and OMC std). The validation of the proposed predictive correlations was done by using test results of another set of sandy soil samples not used in the development of the correlations. The results of the analyses showed that variation between experimental and predicted values of gamma dmod is within +- 4 % confidence interval and that of OMC mod is within +- 2.0 %. Further, based on the test results, an effort has been made to investigate the effect of fines (finer than 75 mu m) on compaction characteristics. It was observed that gamma dmax both in case of standard and modified proctor increases with increase in fines content up to 35% and beyond that it decreases. However, the value of OMC in both the cases decreases with increase in fine content. The correlations proposed in this paper may be very useful during the project preliminary/ pre-feasibility stages in the field of Geotechnical Engineering. (author)

272

The Experimental Manpower Laboratory for Corrections: Phase II. Final Report (March 1, 1970-August 31, 1971).  

Science.gov (United States)

This report covers these five major projects of the Experimental Manpower Laboratory for Corrections: (1) a manpower training program for Alabama prisoners, (2) an experiment in contingency management, (3) implementation of token economy in Draper Correctional Center, (4) a manpower training project for correctional officers, and (5) a followup…

Rehabilitation Research Foundation, Elmore, AL.

273

Biodiesel from soybean oil: experimental procedure of transesterification for organic chemistry laboratories  

International Nuclear Information System (INIS)

The transesterification procedure of triacylglycerides from soybean oil (in natura and waste oil) to give biodiesel was adapted to semi-micro laboratory scale as an additional experimental technique of nucleophilic acyl substitution for undergraduate courses in Chemistry and related areas. (author)

274

New metal working problems overcome in building nuclear fusion experimental laboratory  

Energy Technology Data Exchange (ETDEWEB)

Completely new metal working problems had to be overcome by DE PRETTO-ESCHER WYSS, Schio (Italy), a member of the SULZER Group, in the building of the mechanical supporting structure for the nuclear fusion experimental laboratory in Culham (GB). This structure forms part of the Joint European Torus (JET) project for the European Atomic Energy Commission (Euratom).

1985-01-01

275

New metal working problems overcome in building nuclear fusion experimental laboratory  

International Nuclear Information System (INIS)

Completely new metal working problems had to be overcome by DE PRETTO-ESCHER WYSS, Schio (Italy), a member of the SULZER Group, in the building of the mechanical supporting structure for the nuclear fusion experimental laboratory in Culham (GB). This structure forms part of the Joint European Torus (JET) project for the European Atomic Energy Commission (Euratom). (Auth.)

276

Experimental investigation of high temperature and high pressure coal gasification  

International Nuclear Information System (INIS)

Highlights: ? Gasification kinetics at temperature up to 1600 °C and pressure up to 0.5 MPa. ? Experimental investigation of pyrolysis under realistic conditions. ? Experiments in lab-scale using three different setups. ? Comparison of lab-scale data to experimental results from a pilot-scale gasifier. -- Abstract: Pyrolysis and gasification behavior is analyzed at operation conditions relevant to industrial scale entrained flow gasifiers. A wire mesh reactor and the Pressurized High Temperature Entrained Flow Reactor (PiTER) are used to measure volatile yield of Rhenish lignite, a bituminous coal and German anthracite at high temperature and high pressure. In the wire mesh reactor at 1000 °C a significant influence of pressure on volatile yield is observed. For lignite the volatile yield (daf) decreases from 57 wt% at atmospheric pressure to 53 wt% at 5.0 MPa. In the same pressure interval the volatile yield of the bituminous coal strongly decreases, whereas no significant influence of pressure on the volatile yield of anthracite is detected. In entrained flow experiments (PiTER) at higher temperature and 0.5 MPa an enhanced devolatilization of the lignite is observed. At 1200 °C, the maximum volatile yield is 62 wt% and it increases to 67 wt% at 1400 °C. In entrained flow gasification experiments with Rhenish lignite a high level of conversion is measured at atmospheric pressure and at 0.5 MPa. At both pressures, coal conversion increases with temperature and residence time. The highest conversion of 96 wt% is achieved at a particle residence time of 1.3 s, at a temperature of 1600 °C, and a pressure of 0.5 MPa. The experimental results show a large influence of operation parameters on pyrolysis and gasification behavior of Rhenish lignite. The volatile release in the pyrolysis stage and the high level of conversion after a short residence time indicate that Rhenish lignite is suitable for gasification in an entrained flow reactor. The reactivities of char samples that are collected from the hot reaction zone of the PiTER are measured in a pressurized thermogravimetric analyzer (PTGA) at lower temperature (600–850 °C). The pyrolysis temperature in the entrained flow experiments significantly influences the reaction rate in the PTGA at lower temperature. With increasing pyrolysis temperature (1200–1600 °C) a continuous loss of reactivity is observed.

277

Experimental Investigation of Piston Rings for Internal Combustion Engines  

DEFF Research Database (Denmark)

One of the major prerequisites for calculating piston ring friction is a good description of the tribological situation. A very important condition for describing the frictional behavior of a piston ring correctly is knowledge about the amount of lubricant present. For piston rings the external load may be established by measuring the pressure distribution, i.e. the pressure drop in the piston ring package. Speed and temperature may also be established. The amount and distribution of oil present is, however, not easily determined. It is often assumed that it operates under fully flooded conditions, but this is not the case in real life operation. These problems forms the basis for the experimental investigation. In large two-stroke engines the cylinder oil is supplied to the bearing at discrete locations on the cylinder liner at a specific rate at a certain time. The shifting in lubrication regimes and the non-uniform oil distribution opens for the possibility of starved conditions for the piston ring bearing. Therefore it is important to measure the oil distribution on the liner as a function of the operating conditions. The amount of lubricant available is reflected in the friction absorbed in the bearing. Since the frictional forces are small compared to the rest of the acting forces the rig is designed such that the piston is fixed while the cylinder liner moves. This approach makes it simple to measure the parameters mentioned above by putting the instrumentation in the piston assembly. The aim of this paper is to investigate the tribological condition between a piston ring and cylinder. A test apparatus is used to study the interaction between a piston ring and a cylinder liner. In large two stroke engines with cross head bearings the piston height is small compared to smaller four stroke engines where the skirt transfers the guide forces to the cylinder liner. The power loss due to piston skirt friction is estimated by comparing two different piston designs. The piston ring experiences hydrodynamic, mixed and boundary lubrication and the squeeze effect of the piston ring is significant. Experimental results are presented and the influence from speed, number of piston rings, lubrication oil type and supply oil is discussed.

Klit, Peder

2008-01-01

278

Experimental Investigation of a Morphing Nacelle Ducted Fan  

Science.gov (United States)

The application of Circulation Control to the nacelle of a shrouded fan is proposed as a means to enhance off-design performance of the shrouded fan. Typically, a fixed geometry shroud is efficient at a single operating condition. Modifying circulation about the fixed geometry is proposed as a means to virtually morph the shroud without moving surfaces. This approach will enhance off-design-point performance with minimal complexity, weight, and cost. Termed the Morphing Nacelle, this concept provides an attractive propulsion option for Vertical Take-off and Landing (VTOL) aircraft, such conceptual Personal Air Vehicle (PAV) configurations proposed by NASA. An experimental proof of concept investigation of the Morphing Nacelle is detailed in this paper. A powered model shrouded fan model was constructed with Circulation Control (CC) devices integrated in the inlet and exit of the nacelle. Both CC devices consisted of an annular jet slot directing a jet sheet tangent to a curved surface, generally described as a Coanda surface. The model shroud was tailored for axial flight, with a diffusing inlet, but was operated off-design condition as a static lifting fan. Thrust stand experiments were conducted to determine if the CC devices could effectively improve off-design performance of the shrouded fan. Additional tests were conducted to explore the effectiveness of the CC devices a means to reduce peak static pressure on the ground below a lifting fan. Experimental results showed that off-design static thrust performance of the model was improved when the CC devices were employed under certain conditions. The exhaust CC device alone, while effective in diffusing the fan exhaust and improving weight flow into shroud inlet, tended to diminish performance of the fan with increased CC jet momentum. The inlet CC device was effective at reattaching a normally stalled inlet flow condition, proving an effective means of enhancing performance. A more dramatic improvement in static thrust was obtained when the inlet and exit CC devices were operated in unison, but only over a limited range of CC jet momentum. Operating the nacelle inlet and exit CC devices together proved very effective in reducing peak ground plane static pressure, while maintaining static thrust. The Morphing Nacelle concept proved effective at enhancing off-design performance of the model; however, additional investigation is necessary to generalize the results.

Kondor, Shayne A.; Moore, Mark

2005-01-01

279

REVIEW OF EXPERIMENTAL STUDIES INVESTIGATING THE RATE OF STRONTIUM AND ACTINIDE ADSORPTION BY MONOSODIUM TITANATE  

Energy Technology Data Exchange (ETDEWEB)

A number of laboratory studies have been conducted to determine the influence of mixing and mixing intensity, solution ionic strength, initial sorbate concentrations, temperature, and monosodium titanate (MST) concentration on the rates of sorbate removal by MST in high-level nuclear waste solutions. Of these parameters, initial sorbate concentrations, ionic strength, and MST concentration have the greater impact on sorbate removal rates. The lack of a significant influence of mixing and mixing intensity on sorbate removal rates indicates that bulk solution transport is not the rate controlling step in the removal of strontium and actinides over the range of conditions and laboratory-scales investigated. However, bulk solution transport may be a significant parameter upon use of MST in a 1.3 million-gallon waste tank such as that planned for the Small Column Ion Exchange (SCIX) program. Thus, Savannah River National Laboratory (SRNL) recommends completing the experiments in progress to determine if mixing intensity influences sorption rates under conditions appropriate for this program. Adsorption models have been developed from these experimental studies that allow prediction of strontium (Sr), plutonium (Pu), neptunium (Np) and uranium (U) concentrations as a function of contact time with MST. Fairly good agreement has been observed between the predicted and measured sorbate concentrations in the laboratory-scale experiments.

Hobbs, D.

2010-10-01

280

Experimental investigations of the vertically loaded small scale bored piles  

Directory of Open Access Journals (Sweden)

Full Text Available At present, while evaluating bored piles load capacity in clay soils by CPT data, the depth of active area below the end face plane, within which the averaging of CPT values takes place, is taken as different in different Codes. Thus, for instance, in native Codes and Recommendations the depth of active area is taken from 2 to 4 pile diameters. In foreign Codes such as Belorussian, the depth of active area is taken up to 4 pile diameters and in European Codes - within 0,8-4 pile diameters. In order to specify the regularities of active area forming at different stages of loading, in-situ experimental investigations of large scale models have been carried out. At the test site, two small scale bored piles with the diameter of 130 mm were penetrated into the soil to the depth of 1100 m. The investigations were carried out in two stages: the first - pile static test with measuring of soil vertical displacements with the help of deep marks; the second - digging out soil around the pile and soil sampling at different depths. According to the results of the investigations carried out, the depth of the active area while reaching the limit state was determined to be about two pile diameters. With significant pile settlements (more than 0,58 d, the dimensions of this area do not exceed three pile diameters below the end face plane, and two diameters to the side from the pile axis. Within the lateral surface the significant variation of soil physical characteristics appears to be at the distance not less than 0,4 pile diameter from the lateral surface. Due to investigations’ results, it can be noted that in case of bored pile load less than the limit one, the depth of the active area is about two pile diameters. When the pile reaches its limit state, that provokes significant settlements, zone of compaction does not exceed three diameters to the depth and two diameters to the side from the pile axis.

Glazachev Anton Olegovich

2014-04-01

 
 
 
 
281

An experimental investigation of pump as turbine for micro hydro application  

International Nuclear Information System (INIS)

This paper presents the results of an experimental investigation of a centrifugal pump working as turbine (PAT). An end suction centrifugal pump was tested in turbine mode at PAT experimental rig installed in the Mechanical Engineering Laboratory of Universiti Tenaga Nasional. The pump with specific speed of 15.36 (m, m3/s) was used in the experiment and the performance characteristic of the PAT was determined. The experiment showed that a centrifugal pump can satisfactorily be operated as turbine without any mechanical problems. As compared to pump operation, the pump was found to operate at higher heads and discharge values in turbine mode. The best efficiency point (BEP) in turbine mode was found to be lower than BEP in pump mode. The results obtained were also compared to the work of some previous researchers.

282

Subsurface investigation of the Energy Systems Research Laboratory site at Oak Ridge National Laboratory  

International Nuclear Information System (INIS)

Subsurface soil from the site of the proposed Energy Systems Research Laboratory was examined to determine radioactive concentration levels. This study was undertaken because the proposed site is in close proximity to the former Solid Waste Storage Area-2. A total of 25 cores were taken, ranging in depth from 4 to 9 feet, and the soil samples were analyzed for gamma-, beta-, and alpha-emitting isotopes. Water taken from 13 of the core holes was analyzed to determine tritium, gross beta, and gross alpha levels. None of the samples analyzed were found to be significantly higher than background samples collected throughout eastern and central Tennessee. No special health physics precautions are expected to be needed for the excavation at the site, other than using the excavated soil as backfill at burial sites on the reservation

283

LABORATORY INVESTIGATIONS OF SILICATE MUD CONTAMINATION WITH CALCIUM  

Directory of Open Access Journals (Sweden)

Full Text Available The silicate-based drilling fluid is a low solids KCl/polymer system with the addition of soluble sodium or potassium silicate to enhance inhibition and wellbore stability. Silicate-based drilling fluids exhibit remarkable shale and chalk stabilizing properties, resulting in gauge hole and the formation of firm cuttings when drilling reactive shales and soft chalks. Silicates protect shales by in-situ gellation when exposed to the neutral pore fluid and precipitation, which occurs on contact with divalent ions present at the surface of the shale. Also, silicates prevent the dispersion and washouts when drilling soft chalk by reacting with the Ca2+ ions present on chalk surfaces of cutting and wellbore to form a protective film. The silicate-based drilling fluid can be used during drilling hole section through shale interbeded anhydrite formations because of its superior shale stabilizing characteristics. However, drilling through the anhydrite can decrease the silicate concentration and change rheological and filtration fluid properties. So, the critical concentration of calcium ions should be investigated by lab tests. This paper details the mechanism of shale inhibition using silicate-based drilling fluid, and presents results of lab tests conducted to ascertain the effect of Ca2+ ions on silicate level in the fluid and the fluid properties.

Nediljka Gaurina-Me?imurec

2004-12-01

284

Laboratory and Theoretical Investigations on Mechanical Behavior of PLFG Mixture  

Directory of Open Access Journals (Sweden)

Full Text Available Phosphogypsum-lime-flyash-gravel Mixture (PLFG is usually used to strengthen road foundation of geotechnical engineering. It is important to correctly understand its mechanical behavior before corresponding design. In this present paper, compaction test, one-dimensional compression test and dry-shrinkage test were conducted to determine optimum mixture ration of PLFG. compression test on PLFG with optimum ration was carried out in order to investigate its stress-strain curve. Experiment data show that PLFG is with high bearing capacity and good stiffness. A new composite-exponent model was established, which is available for both hardening and softening type strain-stress curves of PLFG. Mathematical behavior of the presented model is far better than others to describe PLFG’s structural property. Finally, comparison between PLFG tested data and new model simulation was performed and good agreements have been found. This research is helpful for engineering sustainable utilization of to bring economy and to reduce environmental pollution.

Wang Wei

2013-01-01

285

An Investigation of Laboratory-Grown "Ice Spikes"  

CERN Document Server

We have investigated the formation of 10-50 mm long ``ice spikes'' that sometimes appear on the free surface of water when it solidifies. By freezing water under different conditions, we measured the probability of ice spike formation as a function of: 1) the air temperature in the freezing chamber, 2) air motion in the freezing chamber (which promotes evaporative cooling), 3) the quantity of dissolved salts in the water, and 4) the size, shape, and composing material of the freezing vessel. We found that the probability of ice spike formation is greatest when the air temperature is near -7 C, the water is pure, and the air in the freezing chamber is moving. Even small quantities of dissolved solids greatly reduce the probability of ice spike formation. Under optimal conditions, approximately half the ice cubes in an ordinary ice cube tray will form ice spikes. Guided by these observations, we have examined the Bally-Dorsey model for the formation of ice spikes. In this model, the density change during solidi...

Libbrecht, K G

2003-01-01

286

Laboratory scale investigation of uranium melting and casting  

International Nuclear Information System (INIS)

In this work, melting and casting experiments were undertaken to produce cast U rods of good quality, using U derbies produced locally. The effect of various melting and casting parameters on the quality of the U rods produced were investigated. These parameters were: melting temperature, holding time at that temperature, and cast rod diameter. The melting temperatures used were: 1200, 1300 and 14000C for holding periods ranging from 10-30 min. Rods of diameter 1 and 2 cm were cast and the length was 5 cm in all cases. Radiographic, X-ray diffraction, metallographic, density and hardness techniques were used for examination of the rods and as well as identification of inclusions. Casting was done in a vacuum resistance furnace using graphite crucibles and moulds coated with magnesia to minimize carbon pick up. Rods of 2 cm diameter melted at 12000C and cast with holding time 10 min. gave lowest inclusion content and the highest density (18.85 g/cc). These conditions also gave the lowest hardness (VHN 236) which is the closest to that of the cast pure U metal (VHN 220). (author)

287

Site Safety Plan for Lawrence Livermore National Laboratory CERCLA investigations  

Energy Technology Data Exchange (ETDEWEB)

The safety policy of LLNL is to take every reasonable precaution in the performance of work to protect the environment and the health and safety of employees and the public, and to prevent property damage. With respect to hazardous agents, this protection is provided by limiting human exposures, releases to the environment, and contamination of property to levels that are as low as reasonably achievable (ALARA). It is the intent of this Plan to supply the broad outline for completing environmental investigations within ALARA guidelines. It may not be possible to determine actual working conditions in advance of the work; therefore, planning must allow the opportunity to provide a range of protection based upon actual working conditions. Requirements will be the least restrictive possible for a given set of circumstances, such that work can be completed in an efficient and timely fashion. Due to the relatively large size of the LLNL Site and the different types of activities underway, site-specific Operational Safety Procedures (OSPs) will be prepared to supplement activities not covered by this Plan. These site-specific OSPs provide the detailed information for each specific activity and act as an addendum to this Plan, which provides the general plan for LLNL Main Site operation.

Bainer, R.; Duarte, J.

1993-07-01

288

Experimental Investigation of the NASA Common Research Model  

Science.gov (United States)

An experimental aerodynamic investigation of the NASA Common Research Model has been conducted in the NASA NTF (National Transonic Facility). Data have been obtained at chord Reynolds numbers of 5, 19.8 and 30 million for the WB and WBT0 configurations. Data have also been obtained at a chord Reynolds number of 5 million for the WBNP, WBT+2 and WBT-2 configurations. Force and moment, surface pressure and surface flow visualization data were obtained but only the force and moment data are presented herein. Model deformation measurements, aeroelastic, nacelle/pylon Reynolds number and tail effects have been assessed. The model deformation measurements showed more twist as you go out the wing span, with a break in the high q(sub infinity) data close to CL = 0.6 which is consistent with separation near the tip. Increases in dynamic pressure give an increase in pitching moment and drag and a decrease in lift for the WB and WBT0 configuration at Mach = 0.7, 0.85 and 0.87. The addition of a nacelle/pylon gave an increase in drag, decrease in lift and a less nose down pitching moment around the design lift condition of 0.5. Increases in chord Reynolds number have been found to follow the normal Reynolds number trends except at the 19.8 million low q(sub infinity) cases. The abnormality of the 19.8 million low q(sub infinity) cases is being investigated. The tail effects also follow the expected trends. All of the data shown fall within the 2-sigma limits for repeatability.

Rivers, Melissa B.; Dittberner, Ashley

2010-01-01

289

Experimental investigation of hydraulic criteria in the fishways  

International Nuclear Information System (INIS)

Migratory Fish travel downstream to reach larger body of water where the food is available. When they grows, migrate upstream to the place of their birth to spawn. In areas where fish have a commercial value and to keep alive these species as a part of environment, care must be done not to stop such migration specially by constructing the dams across the rivers. Diversion dams usually built across the river to divert some portion of the river flow for irrigation lands. In such dams, the engineers must provide a passage called 'FISHWAY'; for fish in order that fish can travel from down stream to the upstream of the dam. Of course, if such structure is not considered, the fish can not travel upstream to spawn, therefore in the long term these species will diminish. In this study a hydraulic model was conducted to investigate the hydraulic conditions of a vertical-slot type of fishway which has been considered for Ramhormoz diversion dam in the province of Khouzestan, Iran. The Froudian hydraulic model with the scale of 1:5 was constructed at the hydraulic laboratory of Shahid Chamran University. Tests were performed for the original design and two other alternatives slot-opening angles. Another fishway called Denil, also was tested. From the observation and data obtained from these tests, it was found that 90-degree slot opening provide suitable hydraulic conditions. Denil fishway also was found to satisfy the hydraulic criteria and due its simplicity and rapid construc and due its simplicity and rapid construction was recommended to be used in this diversion dam. (author)

290

Experimental investigation of hydraulic criteria in the fishways  

Energy Technology Data Exchange (ETDEWEB)

Migratory Fish travel downstream to reach larger body of water where the food is available. When they grows, migrate upstream to the place of their birth to spawn. In areas where fish have a commercial value and to keep alive these species as a part of environment, care must be done not to stop such migration specially by constructing the dams across the rivers. Diversion dams usually built across the river to divert some portion of the river flow for irrigation lands. In such dams, the engineers must provide a passage called 'FISHWAY'; for fish in order that fish can travel from down stream to the upstream of the dam. Of course, if such structure is not considered, the fish can not travel upstream to spawn, therefore in the long term these species will diminish. In this study a hydraulic model was conducted to investigate the hydraulic conditions of a vertical-slot type of fishway which has been considered for Ramhormoz diversion dam in the province of Khouzestan, Iran. The Froudian hydraulic model with the scale of 1:5 was constructed at the hydraulic laboratory of Shahid Chamran University. Tests were performed for the original design and two other alternatives slot-opening angles. Another fishway called Denil, also was tested. From the observation and data obtained from these tests, it was found that 90-degree slot opening provide suitable hydraulic conditions. Denil fishway also was found to satisfy the hydraulic criteria and due its simplicity and rapid construction was recommended to be used in this diversion dam. (author)

Kurdistani, S.M. [Khouzestan Water and Power Authority (K.W.P.A.), Ahwaz (Iran, Islamic Republic of); Bajestan, M.S. [Univ. of Shahid-Chamran, Ahwaz (Iran, Islamic Republic of)

2002-06-15

291

Experimental investigation and mechanistic modelling of dilute bubbly bulk boiling  

Energy Technology Data Exchange (ETDEWEB)

During evaporation the geometric shape of the vapour is not described using thermodynamics. In bubbly flows the bubble shape is considered spheric with small diameters and changing into various shapes upon growth. The heat and mass transfer happens at the interfacial area. The forces acting on the bubbles depend on the bubble diameter and shape. In this work the prediction of the bubble diameter and/or bubble number density in bulk boiling was considered outside the vicinity of the heat input area. Thus the boiling effects that happened inside the nearly saturated bulk were under investigation. This situation is relevant for nuclear safety analysis concerning a stagnant coolant in the spent fuel pool. In this research project a new experimental set-up to investigate was built. The experimental set-up consists of an instrumented, partly transparent, high and slender boiling container for visual observation. The direct visual observation of the boiling phenomena is necessary for the identification of basic mechanisms, which should be incorporated in the simulation model. The boiling process has been recorded by means of video images and subsequently was evaluated by digital image processing methods, and by that data concerning the characteristics of the boiling process were generated for the model development and validation. Mechanistic modelling is based on the derivation of relevant mechanisms concluded from observation, which is in line with physical knowledge. In this context two mechanisms were identified; the growth/-shrink mechanism (GSM) of the vapour bubbles and sudden increases of the bubble number density. The GSM was implemented into the CFD-Code ANSYS-CFX using the CFX Expression Language (CEL) by calculation of the internal bubble pressure using the Young-Laplace-Equation. This way a hysteresis is realised as smaller bubbles have an increased internal pressure. The sudden increases of the bubble number density are explainable by liquid super-heating. The liquid super-heating is only possible if the heat and mass transfer between the phases is slower than the saturation temperature reduction by hydrostatic pressure decreases along the height of the boiling container or due to bubble growth. By activation of the so far inactive micro-bubbles in the liquid bulk volume the bubble number density quickly increases. This effect is modelled by an algebraic function that uses a constant bubble number density in the vicinity of the saturation temperature and applies an exponentially increased bubble number density depending on the liquid super-heating. Based on modelling a local and variable bubble number density numerical flow simulations were performed. The simulations showed that this approach is a suitable model to describe the mechanisms found in the experiments. Model parameters were determined and verified by correlation with the experimental data.

Kutnjak, Josip

2013-06-27

292

Experimental investigation and mechanistic modelling of dilute bubbly bulk boiling  

International Nuclear Information System (INIS)

During evaporation the geometric shape of the vapour is not described using thermodynamics. In bubbly flows the bubble shape is considered spheric with small diameters and changing into various shapes upon growth. The heat and mass transfer happens at the interfacial area. The forces acting on the bubbles depend on the bubble diameter and shape. In this work the prediction of the bubble diameter and/or bubble number density in bulk boiling was considered outside the vicinity of the heat input area. Thus the boiling effects that happened inside the nearly saturated bulk were under investigation. This situation is relevant for nuclear safety analysis concerning a stagnant coolant in the spent fuel pool. In this research project a new experimental set-up to investigate was built. The experimental set-up consists of an instrumented, partly transparent, high and slender boiling container for visual observation. The direct visual observation of the boiling phenomena is necessary for the identification of basic mechanisms, which should be incorporated in the simulation model. The boiling process has been recorded by means of video images and subsequently was evaluated by digital image processing methods, and by that data concerning the characteristics of the boiling process were generated for the model development and validation. Mechanistic modelling is based on the derivation of relevant mechanisms concluded from observation, which is in line with physical knowledge. In this context two mechanisms were identified; the growth/-shrink mechanism (GSM) of the vapour bubbles and sudden increases of the bubble number density. The GSM was implemented into the CFD-Code ANSYS-CFX using the CFX Expression Language (CEL) by calculation of the internal bubble pressure using the Young-Laplace-Equation. This way a hysteresis is realised as smaller bubbles have an increased internal pressure. The sudden increases of the bubble number density are explainable by liquid super-heating. The liquid super-heating is only possible if the heat and mass transfer between the phases is slower than the saturation temperature reduction by hydrostatic pressure decreases along the height of the boiling container or due to bubble growth. By activation of the so far inactive micro-bubbles in the liquid bulk volume the bubble number density quickly increases. This effect is modelled by an algebraic function that uses a constant bubble number density in the vicinity of the saturation temperature and applies an exponentially increased bubble number density depending on the liquid super-heating. Based on modelling a local and variable bubble number density numerical flow simulations were performed. The simulations showed that this approach is a suitable model to describe the mechanisms found in the experiments. Model parameters were determined and verified by correlation with the experimental data.

293

Border collision route to quasiperiodicity: Numerical investigation and experimental confirmation.  

Science.gov (United States)

Numerical studies of higher-dimensional piecewise-smooth systems have recently shown how a torus can arise from a periodic cycle through a special type of border-collision bifurcation. The present article investigates this new route to quasiperiodicity in the two-dimensional piecewise-linear normal form map. We have obtained the chart of the dynamical modes for this map and showed that border-collision bifurcations can lead to the birth of a stable closed invariant curve associated with quasiperiodic or periodic dynamics. In the parameter regions leading to the existence of an invariant closed curve, there may be transitions between an ergodic torus and a resonance torus, but the mechanism of creation for the resonance tongues is distinctly different from that observed in smooth maps. The transition from a stable focus point to a resonance torus may lead directly to a new focus of higher periodicity, e.g., a period-5 focus. This article also contains a discussion of torus destruction via a homoclinic bifurcation in the piecewise-linear normal map. Using a dc-dc converter with two-level control as an example, we report the first experimental verification of the direct transition to quasiperiodicity through a border-collision bifurcation. PMID:16822025

Zhusubaliyev, Zhanybai T; Mosekilde, Erik; Maity, Somnath; Mohanan, Srijith; Banerjee, Soumitro

2006-06-01

294

Experimental investigations of the ''Angara-5'' facility module  

International Nuclear Information System (INIS)

The description and results of experimental investigation of the head module of the ''Angara-5'' facility are presented. The module represents and energy storage consisting of the Arkadiev-Marx generator and double shaping line (DSL). The intermediate DSL electrode is conneeted with the generator by two conductors passing through the separating section with four dielectric partitions. In the course of DSL commutation realized by five gass-filled commutators internal electrode charging is performed through the cantilever being isolation induction. Basic DSL characteristics are given. In the process of operation on increasing charge module voltage about 180 pulses with DSL charge voltage-1 MV, 80 pulses with charge voltage 1,6 MV and 10 pulses with 2,1 MV voltage have been performed. In all module operation conditions no break-down in water have been observed. Time spread of commutators switch on not exceeding +- 2,6 ns. Gas discharge channel losses are given. The module power balance under capacitor charging voltage +- 80 kV is presented

295

Glulam-concrete composites: experimental investigation into the connection system  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Timber-concrete composite structures work appropriately when a suitable connection system is included because the degree of interaction between the materials stiffs the structural system. Thereby, it is extremely important to improve the knowledge about their connection system. The purpose of this p [...] aper is to show the results obtained by experimental investigation into push-out shear tests of glulam-concrete specimens. The specimens were designed to simulate the behaviour of composite T beams and the connection system was constituted by steel hooks - got by the division of steel bars used in reinforced concrete members - and by perforated steel plates, both glued with epoxy adhesive. They were tested under shear forces with constant loading rate. Six specimens of each group were made, considering two different diameters for the hooks (8 and 10 mm) and 4.75 mm thick perforated steel plates. The stiffness reached by steel hooks confirms their suitability for the use in composite timber-concrete systems.

José Luiz, Miotto; Antonio Alves, Dias.

296

Glulam-concrete composites: experimental investigation into the connection system  

Directory of Open Access Journals (Sweden)

Full Text Available Timber-concrete composite structures work appropriately when a suitable connection system is included because the degree of interaction between the materials stiffs the structural system. Thereby, it is extremely important to improve the knowledge about their connection system. The purpose of this paper is to show the results obtained by experimental investigation into push-out shear tests of glulam-concrete specimens. The specimens were designed to simulate the behaviour of composite T beams and the connection system was constituted by steel hooks - got by the division of steel bars used in reinforced concrete members - and by perforated steel plates, both glued with epoxy adhesive. They were tested under shear forces with constant loading rate. Six specimens of each group were made, considering two different diameters for the hooks (8 and 10 mm and 4.75 mm thick perforated steel plates. The stiffness reached by steel hooks confirms their suitability for the use in composite timber-concrete systems.

José Luiz Miotto

2011-03-01

297

Experimental investigation on the pressure characteristics of cavity closure region  

Science.gov (United States)

The most complicated component in cavitating flow and pressure distribution is the flow in the cavity closure line. The cavitating flow and pressure distribution provide critical aspects of flow field details in the region. The integral of pressure results of the hydrodynamic forces, indicate domination in the design of a supercavitating vehicle. An experiment was performed in a water tunnel to investigate the pressure characteristics of the cavity closure region. Ventilation methods were employed to generate artificial cavity, and the ventilation rate was adjusted accordingly to obtain the desired cavity length. An array of pressure transducers was laid down the cavity closure line to capture pressure distribution in this region. The experimental results show that there is a pressure peak in the cavity closure region, and the rise rate of pressure in space tends to be higher in the upwind side when the flow is non-axisymmetric. The transient pressure variations during the cavity formation procedure were also present. The method of measurement in this paper can be referenced by engineers. The result helps to study the flow pattern of cavity closure region, and it can also be used to analyze the formation of supercavitating vehicle hydrodynamics.

Wang, Yadong; Yuan, Xulong; Zhang, Yuwen

2012-12-01

298

An experimental investigation on thermal exposure during bone drilling.  

Science.gov (United States)

This study presents an experimental investigation of the effects of spindle speed, feed rate, and depth of drilling on the temperature distribution during drilling of the cortical section of the bovine femur. In an effort to reduce measurement uncertainties, a new approach for temperature measurements during bone drilling is presented in this study. The new approach is based on a setup for precise positioning of multiple thermocouples, automated data logging system, and a computer numerically controlled (CNC) machining system. A battery of experiments that has been performed to assess the uncertainty and repeatability of the new approach displayed adequate results. Subsequently, a parametric study was conducted to determine the effects of spindle speed, feed rate, hole depth, and thermocouple location on the measured bone temperature. This study suggests that the exposure time during bone drilling far exceeds the commonly accepted threshold for thermal injury, which may prevail at significant distances from the drilled hole. Results of this study suggest that the correlation of the thermal exposure threshold for bone injury and viability should be further explored. PMID:22483188

Lee, Jueun; Ozdoganlar, O Burak; Rabin, Yoed

2012-12-01

299

Border collision route to quasiperiodicity: Numerical investigation and experimental confirmation  

Science.gov (United States)

Numerical studies of higher-dimensional piecewise-smooth systems have recently shown how a torus can arise from a periodic cycle through a special type of border-collision bifurcation. The present article investigates this new route to quasiperiodicity in the two-dimensional piecewise-linear normal form map. We have obtained the chart of the dynamical modes for this map and showed that border-collision bifurcations can lead to the birth of a stable closed invariant curve associated with quasiperiodic or periodic dynamics. In the parameter regions leading to the existence of an invariant closed curve, there may be transitions between an ergodic torus and a resonance torus, but the mechanism of creation for the resonance tongues is distinctly different from that observed in smooth maps. The transition from a stable focus point to a resonance torus may lead directly to a new focus of higher periodicity, e.g., a period-5 focus. This article also contains a discussion of torus destruction via a homoclinic bifurcation in the piecewise-linear normal map. Using a dc-dc converter with two-level control as an example, we report the first experimental verification of the direct transition to quasiperiodicity through a border-collision bifurcation.

Zhusubaliyev, Zhanybai T.; Mosekilde, Erik; Maity, Somnath; Mohanan, Srijith; Banerjee, Soumitro

2006-06-01

300

An experimental investigation of underwater pulsed laser forming  

Science.gov (United States)

Laser forming is a new forming technology, which deforms a metal sheet using laser-induced thermal stresses. This paper presents an experimental investigation of pulsed laser forming of stainless steel in water and air. The effects of cooling conditions on bending angle and morphology of the heat affected zone (HAZ) are studied. It is shown that the case of the top surface in air and the bottom surface immersed in water has the greatest bending angle based on the forming mechanism of TGM. The water layer above the sample decreases the coupling energy, leading to a small bending angle. For a thin water thickness (1 mm), the water effects on the HAZ are limited. As water layer thickness increases (5 mm), the concave shape of the HAZ is more remarkable and irregular because the shock waves by high laser energy heating water are fully developed. However, the area and the depth of the HAZ become less significant when water thickness is 10 mm due to the long pathway that laser undergoes.

Shen, Hong; Ran, Maoli; Hu, Jun; Yao, Zhenqiang

2014-11-01

 
 
 
 
301

Experimental Investigation of Energy Saving in Referigeration System  

Directory of Open Access Journals (Sweden)

Full Text Available This Research deals with experimental investigation of energy saving in refrigeration system. We have all experienced a sensation of heat when passing behind a functioning refrigerator or air conditioner. The cause of this phenomenon is due to thr air condenser, a heat exchanger made up of tubes with air fins attached to the back of the device. This is where the cooling fluid condenses by releasing its heat into the ambient air. To utilize this heat, a water fine water droplet is project to absorb this ambient hot air to the atmosphere. so by decreasing condenser temperature we obtain the system’s energy consumption, humidification processes were initiated. The principle consists of saturating the ambient air in contact with the exchanger by projecting fine water droplets. Humidification of the air intensifies the heat exchange on the air side and reduces the cooling fluid’s condensation temperature. This lowers the compression rate in the cooling cycle and improves the compressor’s consumption of electrical power. The study is mainly focused on the Condenser to reduce the condenser work to save the electrical power.

Inder Singh Nagar

2014-08-01

302

Experimental investigation of premixed combustion within highly porous media  

International Nuclear Information System (INIS)

This paper reports on an experimental investigation of premixed methane/air combustion stabilized within a reticulated partially stabilized zirconia foam burner that was performed. A flame holder was used to extend the stability range to allow a stable flame to be maintained for a variety of flow rate and equivalence ratio combinations. The stability range, temperature distributions, and emissions were examined over a range of equivalence ratios and flow rates. The flame was found to be axisymmetric for all conditions in which the reactants were sufficiently well mixed and the flow distribution was sufficiently uniform. Burning speeds were measured that were well in excess of the laminar flame speed. The axial temperature distribution (measured around the burner annulus) in the postflame zone was found to be relatively insensitive to flow rate but dependent upon the burner core length. Very low concentrations of NOx were found for fuel/air equivalence ratios of less than about 0.9. Measured O2 concentrations followed the equilibrium trend relatively well

303

Numerical and experimental investigation of a mild combustion burner  

Energy Technology Data Exchange (ETDEWEB)

An industrial burner operating in the MILD combustion regime through internal recirculation of exhaust gases has been characterized numerically. To develop a self-sufficient numerical model of the burner, two subroutines are coupled to the CFD solver to model the air preheater section and heat losses from the burner through radiation. The resulting model is validated against experimental data on species concentration and temperature. A 3-dimensional CFD model of the burner is compared to an axisymmetric model, which allows considerable computational saving, but neglects some important burner features such as the presence of recirculation windows. Errors associated with the axisymmetric model are evaluated and discussed, as well as possible simplified procedures for engineering purposes. Modifications of the burner geometry are investigated numerically and suggested in order to enhance its performances. Such modifications are aimed at improving exhaust gases recirculation which is driven by the inlet air jet momentum. The burner is found to produce only 30 ppm{sub v} of NO when operating in MILD combustion mode. For the same air preheating the NO emissions would be of approximately 1000 ppm{sub v} in flame combustion mode. It is also shown that the burner ensures more homogeneous temperature distribution in the outer surfaces with respect to flame operation, and this is attractive for burners used in furnaces devoted to materials' thermal treatment processes. The effect of air excess on the combustion regime is also discussed. (author)

Galletti, Chiara; Parente, Alessandro; Tognotti, Leonardo [Department of Chemical Engineering, Industrial Chemistry and Materials Science, University of Pisa, via Diotisalvi 2, 56126 Pisa (Italy)

2007-12-15

304

Experimental investigation of hardfaced martensitic steel under slurry abrasion conditions  

International Nuclear Information System (INIS)

Wear by slurry abrasion is a potential problem in engineering components subjected to particulate flow. The life of the components under slurry abrasive wear situations is primarily decided by operating conditions and the materials properties. Martensitic steels are widely used for abrasion resistant applications. The present work reports slurry abrasion response of hardfacing martensitic steel under a wide range of experimental conditions. The response data is generated using systematic and simultaneous variation of test parameters. The experiments were performed using silica sand slurry with different slurry concentration, particle size, sliding distance and load. The results of the investigation suggest that slurry concentration had relatively stronger effect than normal load. The wear volume loss exhibited an increasing trend with increasing severity of test parameters. An empirical equation is proposed to describe the interactive effect of the test parameters, abrasive particle properties and material property. SEM (Scanning Electron Microscope) studies revealed different morphology of the worn surfaces which was attributed to mild to severe slurry abrasion test conditions.

305

Glulam-concrete composites: experimental investigation into the connection system  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Timber-concrete composite structures work appropriately when a suitable connection system is included because the degree of interaction between the materials stiffs the structural system. Thereby, it is extremely important to improve the knowledge about their connection system. The purpose of this p [...] aper is to show the results obtained by experimental investigation into push-out shear tests of glulam-concrete specimens. The specimens were designed to simulate the behaviour of composite T beams and the connection system was constituted by steel hooks - got by the division of steel bars used in reinforced concrete members - and by perforated steel plates, both glued with epoxy adhesive. They were tested under shear forces with constant loading rate. Six specimens of each group were made, considering two different diameters for the hooks (8 and 10 mm) and 4.75 mm thick perforated steel plates. The stiffness reached by steel hooks confirms their suitability for the use in composite timber-concrete systems.

José Luiz, Miotto; Antonio Alves, Dias.

2011-03-01

306

Experimental and theoretical investigations of a 17 GHz RF gun  

CERN Document Server

We report on experimental and theoretical investigations of a 17 GHz RF photocathode electron gun. This is the first photocathode electron gun to operate at a frequency above 2.856 GHz. The 1.5 cell, pi mode, copper cavity was tested with 50 ns pulses from a 17.150 GHz klystron amplifier built by Haimson Research Corp. A Bragg filter was used at the RF gun to reduce the reflection of parasitic modes back into the klystron. Coupling hole theory in conjunction with cold test measurements was used to determine the field profile in the RF gun. The particle in cell code MAGIC as well as coupled envelope equations were used to simulate the beam dynamics in the RF gun. With power levels of 4 MW, the on axis electric field at the cathode exceeds 300 MV/m, corresponding to an average accelerating gradient of 200 MV/m over the first half cell of the gun. Breakdown was observed at power levels above 5 MW. Electron bunches were produced by 20 mu J, 1 ps UV laser pulses impinging on the RF gun copper photocathode and were...

Brown, W J; Kreischer, K E; Pedrozzi, M; Shapiro, M A; Temkin, R J

1999-01-01

307

An experimental investigation of deformationinduced heating during tensile testing  

Science.gov (United States)

An experimental investigation of deformation heating during uniaxial tensile testing is presented for Armco interstitial-free steel (I. F. steel) and stainless steel type 310 (310SS). Temperature distributions were measured along the specimen length for tests conducted at various strain rates and subjected to various heat flow conditions (in stirred water, in air, and with insulation). Maximum temperature rises of 75 °C and 118 °C were recorded in the neck. I.F. steel shows a decreasing failure strain from ˜45 pct to ˜40 pct when natural temperature gradients develop. 310SS shows a decreasing failure strain from ˜60 pct to ˜42 pct when natural heating is allowed. In 310SS, the developed temperature gradient accounts for about one-third of this ductility reduction while the uniform temperature rise accounts for about two-thirds. The uniform temperature rise influences ductility via a temperaturedependent work-hardening rate. These results have been qualitatively compared with finite element modeling of these tensile tests using constitutive equations generated previously. This study provides the basis for understanding several modified forming processes and demonstrates that care must be taken in interpreting data from "standard" tensile tests since such tests reflect the thermal properties of the material and environment as well as mechanical behavior.

Lin, Muh-Ren; Wagoner, R. H.

1991-01-01

308

Dry vs. Cryogenic Orthogonal Hard Machining: an Experimental Investigation  

Science.gov (United States)

Friction, and consequently heat generation in the cutting zone, significantly affects the tool life, surface integrity and dimensional accuracy, apart from other machining results. Application of a coolant in a cutting process can increase tool life and dimensional accuracy, decrease heat generation, and consequently cutting temperatures, reduce surface roughness and the amount of energy consumed in cutting process, and thus improve the productivity. Furthermore, coolant application also affects the surface microstructural alterations (i.e., white and dark layers) due to a machining operation, which have a significant influence on product performance and life. This paper presents the results of an experimental investigation to determine the effects of cryogenic coolant application on tool wear, cutting forces and machined surface alterations during orthogonal machining of hardened AISI 52100 bearing steel (54±1 HRC). Experiments were performed for dry and cryogenic cutting conditions using chamfered PCBN tool inserts at varying cutting conditions (cutting speed and feed rate). For cryogenic cutting conditions the fluid was applied in the form of a liquid nitrogen jet directed on the three shear cutting zones. Cutting forces, tool wear, cutting temperatures, surface hardness modifications and microstructure alterations were studied in order to evaluate the effects of extreme in-process cooling. The results indicate that cryogenic cooling has the potential to be used for surface integrity enhancement for improved product life and more sustainable functional performance.

Umbrello, D.; Caruso, S.; Di Renzo, S.; Jayal, A. D.; Dillon, O. W.; Jawahir, I. S.

2011-05-01

309

An experimental investigation of cross-flow turbine efficiency  

Energy Technology Data Exchange (ETDEWEB)

An experimental investigation was conducted to study the effect of some geometric parameters on the efficiency of the cross-flow turbine. Turbine models were constructed with three different numbers of blades, three different angles of water entry to the runner, and three different inner-to-outer diameter ratios. Nozzles were also constructed for the experiments to match the three different angles of water entry to the runner. A total of 27 runners were tested with the three nozzles. The results of the experiments clearly indicated that efficiency increased with increase in the number of blades. Moreover, it was determined that an increase in the angle of attack beyond 24 deg does not improve the maximum turbine efficiency. In addition, as a result of these experiments, it was determine that for a 24 deg angle of attack 0.68 was the most efficient inner-to-outer diameter ratio, whereas for higher angles of attack the maximum efficiency decreases with an increase in the diameter ratio from 0.60 to 0.75.

Desai, V.R. (Indian Inst. of Technology, Kharagpur (India). Dept. of Civil Engineering); Aziz, N.M. (Clemson Univ., SC (United States). Dept. of Civil Engineering)

1994-09-01

310

Experimental Investigation on Characteristics of Polythene Waste Incorporated Concrete  

Directory of Open Access Journals (Sweden)

Full Text Available The Disposal of large quantity of plastic cover may cause pollution of land, water bodies and air. The proposed concrete which is made up by adding plastic in concrete may help to reuse the plastic cover as one of the constituent’s material of concrete, to improve the certain properties of concrete. The properties of concrete as varying percentages of plastic will test for compressive strength and Split tensile strength and flexural strength shows that an appreciable improvement in tensile strength of concrete can be achieved by introducing cut pieces of plastic cover. This paper presents the experimental investigation of feasibility of polythene cover post consumer waste used for food packaging. The numbers of samples is prepared in M25 concrete mix with required water/ cement ratio. Plastic waste was converted in to fiber size form and added waste for three aspect ratios, is casted into desire shape and size as per requirement of the tests. Each specimen was cured for 7 days, 14 days, and 28 days. The workability of compression, tension and flexural tests were carried out. The results are compared with normal concrete was observed.

J. Simson Jose

2014-04-01

311

Experimental investigation of statistical models describing distribution of counts  

International Nuclear Information System (INIS)

The binomial, Poisson and modified Poisson models which are used for describing the statistical nature of the distribution of counts are compared theoretically, and conclusions for application are considered. The validity of the Poisson and the modified Poisson statistical distribution for observing k events in a short time interval is investigated experimentally for various measuring times. The experiments to measure the influence of the significant radioactive decay were performed with 89Ym(T1/2=16.06 s), using a multichannel analyser (4096 channels) in the multiscaling mode. According to the results, Poisson statistics describe the counting experiment for short measuring times (up to T=0.5T1/2) and its application is recommended. However, analysis of the data demonstrated, with confidence, that for long measurements (T?T1/2) Poisson distribution is not valid and the modified Poisson function is preferable. The practical implications in calculating uncertainties and in optimizing the measuring time are discussed. Differences between the standard deviations evaluated on the basis of the Poisson and binomial models are especially significant for experiments with long measuring time (T/T1/2?2) and/or large detection efficiency (?>0.30). Optimization of the measuring time for paired observations yields the same solution for either the binomial or the Poisson distribution. (orig.)

312

HESS Opinions On the use of laboratory experimentation: "Hydrologists, bring out shovels and garden hoses and hit the dirt"  

Directory of Open Access Journals (Sweden)

Full Text Available From an outsider's perspective, hydrology combines field work with modelling, but mostly ignores the potential for gaining understanding and conceiving new hypotheses from controlled laboratory experiments. Sivapalan (2009 pleaded for a question- and hypothesis-driven hydrology where data analysis and top-down modelling approaches lead to general explanations and understanding of general trends and patterns. We discuss why and how such understanding is gained very effectively from controlled experimentation in comparison to field work and modelling. We argue that many major issues in hydrology are open to experimental investigations. Though experiments may have scale problems, these are of similar gravity as the well-known problems of fieldwork and modelling and have not impeded spectacular progress through experimentation in other geosciences.

M. van der Perk

2010-02-01

313

A Global Remote Laboratory Experimentation Network and the Experiment Service Provider Business Model and Plans  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents results from the IST KAII Trial project ReLAX - Remote LAboratory eXperimentation trial (IST 1999-20827, and contributes with a framework for a global remote laboratory experimentation network supported by a new business model. The paper presents this new Experiment Service Provider business model that aims at bringing physical experimentation back into the learning arena, where remotely operable laboratory experiments used in advanced education and training schemes are made available to a global education and training market in industry and academia. The business model is based on an approach where individual experiment owners offer remote access to their high-quality laboratory facilities to users around the world. The usage can be for research, education, on-the-job training etc. The access to these facilities is offered via an independent operating company - the Experiment Service Provider. The Experiment Service Provider offers eCommerce services like booking, access control, invoicing, dispute resolution, quality control, customer evaluation services and a unified Lab Portal.

Tor Ivar Eikaas

2003-07-01

314

Experimental investigation and mechanical modelling of zircaloy-4 stress corrosion cracking  

International Nuclear Information System (INIS)

In Pressurised Water Reactor fuel assemblies, cladding tubes constitute the first safety barriers against the fission product dissemination. It is therefore essential to ensure their integrity under all the reactor operating conditions. During an important loading, resulting from severe reactor power transients, clad failures can be induced by a Stress Corrosion Cracking phenomenon (SCC) due to the combined action of mechanical loading and gaseous fission products generated by the fuel pellets. The aim of our work is to study the role played by different parameters on the SCC phenomenon of Zircaloy-4 claddings. It is made up of three complementary parts: - the modelling of local mechanical fields applied during laboratory tests; - the design of specific SCC experiments to investigate the influence of several mechanical parameters; - the observation of the damage mechanisms occurring during these different experiments. Coupling mechanical modelling and laboratory tests allowed to obtain some local information which cannot be obtained experimentally. A hierarchical approach was then used to develop accurate constitutive laws of the stress-relieved Zircaloy-4 alloy. The constitutive equations derived from this approach were fitted to the mechanical loading applied during the experiments. The specific SCC tests results and SEM observations proved the existence of a time incubation period, which lasts for an important part of the lifetime measured in the SCC pressurization tests. This incubation period is closely related to the experimental conditions of the laboratory tests. However the incubation period must be distinguished from the actual SCC mechanisms and corresponds to the time required for the metal surface to strip of its oxide layer by mechanical cracking and/or attack of zircon. First results obtained on pre-cracked samples showed that this stage, which introduces an artefact in the experimental test analysis, can be suppressed. Moreover, we have borne out that initiation and propagation of SCC cracks can be very fast when metal is laid bare and when iodine is present. (author)

315

LABORATORY AND NUMERICAL INVESTIGATIONS OF RESIDENCE TIME DISTRIBUTION OF FLUIDS IN LAMINAR FLOW STIRRED ANNULAR PHOTOREACTOR  

Science.gov (United States)

Laboratory and Numerical Investigations of Residence Time Distribution of Fluids in Laminar Flow Stirred Annular Photoreactor E. Sahle-Demessie1, Siefu Bekele2, U. R. Pillai1 1U.S. EPA, National Risk Management Research Laboratory Sustainable Technology Division,...

316

Advanced Laboratory at Texas State University: Error Analysis, Experimental Design, and Research Experience for Undergraduates  

Science.gov (United States)

Physics is an experimental science. In other words, all physical laws are based on experimentally observable phenomena. Therefore, it is important that all physics students have an understanding of the limitations of certain experimental techniques and the associated errors associated with a particular measurement. The students in the Advanced Laboratory class at Texas State perform three detailed laboratory experiments during the semester and give an oral presentation at the end of the semester on a scientific topic of their choosing. The laboratory reports are written in the format of a ``Physical Review'' journal article. The experiments are chosen to give the students a detailed background in error analysis and experimental design. For instance, the first experiment performed in the spring 2009 semester is entitled Measurement of the local acceleration due to gravity in the RFM Technology and Physics Building. The goal of this experiment is to design and construct an instrument that is to be used to measure the local gravitational field in the Physics Building to an accuracy of ±0.005 m/s^2. In addition, at least one of the experiments chosen each semester involves the use of the research facilities within the physics department (e.g., microfabrication clean room, surface science lab, thin films lab, etc.), which gives the students experience working in a research environment.

Ventrice, Carl

2009-04-01

317

Experimental and Computational Investigations of Strain Localization in Metallic Glasses  

Science.gov (United States)

Metallic glasses are metallic alloy systems with disordered atomic structure. Due to their unique amorphous structure, they exhibit an extraordinary set of properties that are ideal for a wide variety of applications ranging from electrical transformers, armor-piercing projectiles, sporting goods and fuel cells to precision gears for micromotors. In particular, owing to their exceptional mechanical properties like near-theoretical strength (1--3 GPa), large elastic strain range (2--3%), and unusual formability above the glass transition temperature, metallic glasses have tremendous potential in structural applications. Unfortunately, their unique structure also gives rise to significant limitations, such as limited ductility at room temperature due to rapid localization of plastic flow in shear bands. However, when the test volumes approach the size of a shear band nucleus (˜50--500 nm), it is believed that shear band formation and propagation can be constrained, leading to enhanced plasticity and failure strength. This study investigates the phenomenon of strain localization using both experimental and computational techniques. On the experimental front, sample size effects on strength, plasticity and deformation modes were explored in a Zr-based bulk metallic glass via micron- and sub-micron scale compression testing. Specimens with diameters ranging from 200 nm to a few microns were fabricated using Focused Ion Beam technique and were tested under uniaxial compression in a nanoindentation set-up with a flat punch tip. Effect of extrinsic factors like specimen geometry and machine stiffness on deformation behavior was discussed. Shear banding was shown to be more stable at this length scale than in macro-scale testing because of a smaller specimen to load frame stiffness ratio. It was found that as the specimen size is reduced to below 300 nm, the deformation mode changes from being discrete and inhomogeneous to more continuous flow including both localized and non-localized contributions at low strains. Moreover, the magnitude of strain bursts was found to decrease with decrease in specimen size. Furthermore, Weibull statistical analysis was performed to investigate the effect of specimen size on yield strength in this metallic glass. It was revealed that the dispersion in strengths increases dramatically with decrease in sample size, attributed to the size distribution of the defects responsible for shear banding. The findings are crucial in designing systems which promote plasticity in metallic glasses by suppressing the shear-band instability and also in direct application of these materials for structural purposes as small components in micro- and nano-scale systems. On the computational front, Molecular Dynamics (MD) simulations have been employed to generate Zr-Cu metallic glass structures. In order to analyze and better understand and visualize the concepts of "free" volume and flow defects in metallic glasses, an electron density model was developed as an upgrade to the traditional hard sphere approaches. Simple tension and shear modes of deformation were simulated using MD in Zr-Cu system, and role of open volume in deformation was studied using the electron density model. In uniaxial tension simulations, effect of temperature and deformation rate is examined, and the process of accumulation of free volume to the point of catastrophic failure is visualized using the Electron Density model. In shear simulations, we find that the as-quenched glass structures undergo homogeneous deformation and do not exhibit any strain localization. However, it is found that by incorporating a cylindrical void in the glass structure as a source of "free" volume, it is possible to induce strain localization. It was found that a critical void diameter of 8A was required to successfully initialize strain localization in this system.

Bharathula, Ashwini

318

An experimental investigation of flow past a dual step cylinder  

Energy Technology Data Exchange (ETDEWEB)

Flow development in the wake of a dual step cylinder has been investigated experimentally using Laser Doppler Velocimetry and flow visualization. The dual step cylinder model is comprised of a large diameter cylinder (D) mounted at the mid-span of a small diameter cylinder (d). The experiments have been performed for a Reynolds number (Re{sub D}) of 1,050, a diameter ratio (D/d) of 2, and a range of large cylinder aspect ratios (L/D). The results show that the flow development is highly dependent on L/D. The following four distinct flow regimes can be identified based on vortex dynamics in the wake of the large cylinder: (1) for L/D {>=} 15, three vortex shedding cells form in the wake of the large cylinder, one central cell bounded by two cells of lower frequency, (2) for 8< L/D {<=} 14, a single vortex shedding cell forms in the wake of the large cylinder, (3) for 2 < L/D {<=} 6, vortex shedding from the large cylinder is highly three-dimensional. When spanwise vortices are shed, they deform substantially and attain a hairpin shape in the near wake, (4) for 0.2 {<=} L/D {<=} 1, the large cylinder induces vortex dislocations between small cylinder vortices. The results show that for Regimes I to III, on the average, the frequency of vortex shedding in the large cylinder wake decreases with L/D, which is accompanied by a decrease in coherence of the shed vortices. In Regime IV, small cylinder vortices connect across the large cylinder wake, but these connections are interrupted by vortex dislocations. With decreasing L/D, the frequency of dislocations decreases and the dominant frequency in the large cylinder wake increases toward the small cylinder shedding frequency. (orig.)

Morton, Chris; Yarusevych, Serhiy [University of Waterloo, Mechanical and Mechatronics Engineering, Waterloo, ON (Canada)

2012-01-15

319

Volcanic ash aggregation: experimental, field and theoretical investigations  

Science.gov (United States)

Particle aggregation is considered as a key process that may affect dispersal and sedimentation of volcanic ash, with significant implications for the associated hazards. Most theoretical studies of particle aggregation have been based on the Smoluchowski Coagulation Equation (SCE), which describes the expected time evolution of the total grain-size distribution under the hypothesis that particles can collide and stick together following specific mathematical relations (kernels). Unfortunately these kernels are not very well understood and quantified. In particular, the probability of sticking is almost completely unknown and it can be described theoretically just in a very approximate way. We have carried out a set of experiments to investigate how the sticking efficiency varies as a function of particle size and velocity. Ash particles larger than 100 micron were suspended in a 4-meters high vertical wind tunnel and recorded in time with a high-speed camera. Filming the interactions of small particles and using a dedicated Particle Tracking Velocimetry software, sticking efficiencies were characterized based on the number of particles that formed aggregates in relation to the number of collisions. Experiments were repeated in order to have a good statistical significance and to cover different environmental conditions (temperature and humidity). We have also carried out field experiments during various eruptions at Sakurajima volcano (Japan) for the characterization of aggregates in situ in combination with high speed recordings and SEM studies. Experimental and field results were then merged with the theoretical framework (SCE) to study the time evolution of different initial grain-size distributions for different external conditions.

Rossi, Eduardo; Bagheri, Gholamhossein; Biasse, Sébastien; Bonadonna, Costanza; Falcone, Jean-Luc; Chopard, Bastien; Pontelandolfo, Piero; Haas, Patrick

2014-05-01

320

Experimental investigations of neutrino oscillations at a fission reactor  

Science.gov (United States)

To investigate the possibility of neutrino oscillations, the positron kinetic energy spectrum was measured using the inverse beta decay of the neutron (?[overbar]_e + p ? e^+ + n) as a detector reaction. The experiment was carried out at the fission reactor of the Institut Laue Langevin at Grenoble, France. The well shielded detector was set up at 8.76 meters from the point-like reactor core in an antineutrino flux of 9.8 x 10^(11) cm^(-2) sec^(-1) . The target protons were provided by a liquid scintillator (total volume of 377 liters) which also served as a positron detector. The product neutrons were moderated in the scintillator and detected by ^3He wire counters via the ^3He (n,p)^3H reaction. A delayed coincidence was required between the prompt positron and the delayed neutron events. The positron energy resolution was 18% FWHM at 1 MeV. The signal to background ratio was better than one to one between 2 MeV and 6 MeV positron energy. With a counting rate of 1.56 counts per hour, 2919 ± 131 neutrino induced events were detected. The shape of the measured positron spectrum was analyzed in terms of parameters for neutrino oscillations. The experimental data are consistent with no oscillations. An upper limit of 0.2 ev^2 (90% c.l.) for the mass-squared differences of the neutrinos was achieved, assuming maximum mixing of two neutrino states. The ratio of the measured to the expected integral yield of positrons was determined to be ?Y(exp)/?Y_(th) = 0.89 ± 0.04 (statistical) ± 0.13 (systematic).

Kwon, Heemin

 
 
 
 
321

Experimental and computational investigation of local scour around bridge piers  

Science.gov (United States)

Experiments and numerical simulations are carried out to study clear-water scour around three bridge piers with cylindrical, square, and diamond cross-sectional shape, respectively. To handle movable-bed channels with embedded hydraulic structures, the fluid-structure interaction curvilinear immersed boundary (FSI-CURVIB) method is employed. The hydrodynamic model solves the unsteady Reynolds-averaged Navier-Stokes (URANS) equations closed with the k-? turbulence model using a second-order accurate fractional step method. Bed erosion is simulated by solving the sediment continuity equation in the bed-load layer using a second-order accurate unstructured, finite-volume formulation with a sand-slide, bed-slope-limiting algorithm. Grid sensitivity studies are carried out to investigate the effect of grid resolution on the predictive capability of the model. Comparisons of the simulations with the experimental data show that for all three cases the agreement is reasonable. A major finding of this work, however, is that the predictive capability of the URANS morphodynamic model improves dramatically for the diamond shape pier for which sediment transport is driven primarily by the shear layers shed from the pier sharp edges. For piers with blunt leading edge, on the other hand, as the circular and square shapes, the URANS model cannot resolve the energetic horseshoe vortex system at the pier/bed junction and thus significantly underpredicts both the scour depth at the nose of the pier and the rate of scour growth. It is also shown that ad hoc empirical corrections that modify the calculated critical bed shear stress to enhance scour rate in the pier leading edge need to be applied with caution as their predictive capabilities are not universal but rather depend on the pier shape and the region of the flow.

Khosronejad, Ali; Kang, Seokkoo; Sotiropoulos, Fotis

2012-03-01

322

Experimental Investigation on the Melt Pool Configuration with the COSMOS  

International Nuclear Information System (INIS)

In general, a two-layer melt pool with a light metallic layer of Fe-Zr on top of oxidic pool was assumed to be a bounding melt configuration in the safety analyses for the severe accidents. The experimental results of the OECD MASCA, however, have shown that when a sufficient amount of non-oxidized zirconium (Zr) is available, then metallic uranium (U) migrates to the metallic layer. The transfer of species between the U, O, Zr melt and the steel can result in a significant density increase of the metallic phase. The density increase of the metallic phase can lead to inverse stratification with an additional heavy metal layer below the oxidic pool. The presence of the metallic layer at the bottom of the lower head is likely to decrease the thickness of the top metallic layer and consequently to increase the risk of the focusing effect. At KAERI, thermodynamic analyses using the GEMINI code were performed to examine the final melt pool configuration during the severe accidents in the APR1400. In this study, based on the thermodynamic analysis results, for an investigation on the molten pool configurations considering the layer inversion of the heavy metallic layer, a series of test, named as the COSMOS (Corium configuration of the molten State in the Most Severe Accidents), are in progress. Since the melt pool configurations were different in the representative accident sequences of the APR1400, a series of test will be performed for the initial melt pool conditions of the major severe accident sequences of the APR1400

323

Experimental investigation of elliptically polarized injection-locked VCSELs  

Science.gov (United States)

Polarization switching (PS) between linear polarizations of a vertical-cavity surface-emitting laser (VCSEL) can appear when this device is subject to orthogonal optical injection. In this type of injection the injected field has a linear polarization orthogonal to that of the free-running VCSEL. In this situation interesting nonlinear dynamics appear, one of which is the existence of an injection-locked solution for which the two linear polarized modes of the VCSEL lock to the master laser frequency. This situation has been theoretically predicted and corresponds to an elliptically polarized injection-locked (EPIL) state. In this paper we report an experimental investigation of the dynamics of a long-wavelength single-transverse mode VCSEL subject to orthogonal optical injection. The free-running VCSEL emits a linearly polarized beam in the so called "parallel" direction. The polarization of the injected light is perpendicular to this state and is termed "orthogonal" polarization. We observe the EPIL state when the frequency of the orthogonal injected light is near the frequency of the parallel polarization. The spectral feature of the EPIL state is verified and the power of each polarization is measured. The EPIL region is measured in the frequency detuning-injected power plane. As current decreases, the frequency detuning range for the EPIL to exist is narrower and shifts toward the negative frequency detuning. Periodic dynamics in which both polarizations oscillate with a frequency very close to the relaxation oscillation frequency is found above the upper boundary of the EPIL region. Below the lower boundary of the EPIL zone, periodic dynamics is found only in the parallel polarization.

Lin, Hong; Pérez, Pablo; Valle, Angel; Pesquera, Luis

2014-05-01

324

Theoretical and experimental investigation of the characteristics of moving melt  

International Nuclear Information System (INIS)

Results of calculations of velocity fields and time characteristics of flow of aluminum melt in a sand-loam casting mold are provided. The experimental data on time characteristics of flowing (moving) melt are obtained. Comparison is made of the experimental and theoretical data

325

CO{sub 2} adsorption: Experimental investigation with kinetics verification and CFD reactor model validation  

Energy Technology Data Exchange (ETDEWEB)

The National Energy Technology Laboratory is investigating a new process for CO{sub 2} capture from large sources such as utility power generation facilities as an alternative to liquid amine based absorption processes. Many, but not all of these advanced dry processes are based upon sorbents composed of supported polyamines. In this analysis, experiments have been conducted in a small facility at different temperatures and compared to CFD reactor predictions using kinetics obtained from TGA tests. This particular investigation compares the predicted performance and the experimental performance of one of these new class of sorbents in a fluidized bed reactor. In the experiment, the sorbent absorbs CO{sub 2} from simulated flue gas in a riser reactor, separates the carbonated particles from the de-carbonated flue gas in a cyclone and then regenerates the sorbent, creating a concentrated stream of pure CO{sub 2} for sequestration. In this work, experimental measurements of adsorption are compared to predictions from a 3-dimensional non-isothermal reacting multiphase flow model. The effects of the gas flow rate and reactor temperature are explored. It is shown that the time duration for CO{sub 2} adsorption decreased for an increase in the gas flow. The details of the experimental facility and the model as well as the comparative analysis between the data and the simulation results are discussed.

Breault, Ronald W, [U.S. DOE; Huckaby, Ernest D. [U.S. DOE; Shadle, Lawrence J [U.S. DOE; Spenik, James L. [REM Engineering PLLC

2013-01-01

326

Experimental investigation of reinforced-concrete Category I structures at high load levels  

International Nuclear Information System (INIS)

A US Nuclear Regulatory Commission-funded experimental program designed to obtain information on the structural behavior of reinforced-concrete buildings has been underway at the Los Alamos National Laboratory since 1980. This information will aid the NRC in evaluating the seismic capacities of existing Seismic Category I buildings. Scale models of reinforced-concrete shear walls and buildings were subjected to static and dynamic tests. Simulated seismic tests were conducted on model structures constructed to two scales (1/30 and 1/10), permitting an evaluation of the effect of scale in experimental investigations of reinforced-concrete structures. Monotonic and cyclic quasistatic tests provide information on strength, stiffness, strength and stiffness degradation, ductility, and general load-deflection behavior up to the ultimate load. The dynamic tests yielded information on natural frequencies, equivalent viscous damping values, initial stiffness and stiffness degradation, and general response behavior. These experimental investigations have indicated that sine-sweep tests are not suitable for reinforced-concrete structures and that the initial stiffness of shear wall structures is less than predicted when assuming an uncracked concrete section

327

Testing geochemical models of bentonite pore water evolution against laboratory experimental data  

International Nuclear Information System (INIS)

ng PCO2 (with log PCO2 values ranging from -3.5 to -7.5 bars produced pH values ranging from 7.9 to 9.6). A second set of calculations investigated disequilibrium between clay and pore fluid in laboratory squeezing cell tests involving pure water (pH = 9.0) or a 1 M NaOH solution (pH = 12.1). Simulations carried out for 100 days (the same timescale as the experiments) showed that smectite remained far from equilibrium throughout, and that the lowering of pH due to smectite hydrolysis was trivial. However, extending the duration of the simulations to that required for clay-fluid equilibrium, necessitated timescales of 7 and 65. years for pure water and 1 M NaOH, respectively, but again produced relatively minor reduction in pH (in the order of 0.1-0.2 pH units). If the (equilibrium) precipitation of secondary minerals was included in the simulations, then not only was the clay-fluid equilibration period extended dramatically (from 7 to 360 years for pure water, and from 65 to 2600. years for 1 M NaOH), but concomitant changes in pH were significant, decreasing from 9.0 to 8.6 (pure water) and from 12.1 to 9.0 (1 M NaOH). Repetition of these latter calculations using an alternative method for ?Gf0 smectite produced an increase in equilibration time for reaction with 1 M NaOH from 2600 to 5000 years, highlighting the potential effects of the uncertainty in thermodynamic data for smectite. A final set of calculations was carried out to investigate both the time- and space-dependent variations in pore fluid composition in laboratory in-diffusion experiments conducted for over 1200 days, initially with pure water and 'spiked' after 271 days with a Na-Ca-OH-Cl solution (pH = 11.7). Here, the sensitivity of the results to both variations in a number of parameters/conditions (porosity, reaction rate of secondary minerals, the degree of mixing of the external fluid reservoirs in the experiments, the effective diffusion coefficient) and the inclusion/exclusion of key processes (clay hydrolysis, secondary mineral precipitation, ion exchange, clay edge protonation-deprotonation reactions) was investigated. These calculations confirmed that smectite dissolution-precipitation reactions alone have an insignificant impact upon pH buffering over laboratory timescales and that the pH buffering observed is most likely controlled by clay protonation-deprotonation reactions, and kinetic secondary mineral (brucite + tobermorite) precipitation. Ion exchange reactions were found to have little effect on pH. Alternative data for the kinetic dissolution of smectite produced no observable differences, and the adoption of a reduced diffusion coefficient produced a poorer fit to experiment results. In conclusion, modelling predicts that the effects of smectite dissolution on the chemistry of bentonite pore waters would be essentially undetectable over experimental time scales, but when the model is combined with plausible constraints on the precipitation of secondary minerals, significant changes in solution chemistry and mineralogy are predicted to occur over time scales that are relevant to repository near-field evolution (hundreds to thousands of years). There are remaining fundamental uncertainties related to the variable chemistry of the smectite clays, the nature of porosity in highly compacted buffer materials, the reactive surface area of smectite, and the thermodynamic properties of these clay minerals. (authors)

328

Analytical and experimental Mark I boiling water reactor containment safety research at the Lawrence Livermore Laboratory  

International Nuclear Information System (INIS)

An overview of research work is discussed here which adresses both large scale experimental and multidimensional analytical containment studies conducted at the Lawrence Livermore Laboratory since 1976. The Mark I Boiling Reactor (BWR) containment design is the subject of interest. In the experimental program, particular focus is placed on quantification of loss-off-coolant-accident (LOCA) induced loads. The focus of the analytical effort is toward understanding of fluid/structure interaction effects due both to LOCA induced loads and safety relief value (SRV) loads in the Mark I BWR pressure suppression wetwell (a segmented torus). (orig.)

329

Experimental investigation of Ca isotopic fractionation during abiotic gypsum precipitation  

Science.gov (United States)

Experiments investigating Ca isotopic fractionation during gypsum precipitation were undertaken in order to elucidate the mechanisms and conditions that govern isotopic fractionation during mineral precipitation. Both stirred and unstirred free drift gypsum precipitation experiments were conducted at constant initial ionic strength (0.6 M) and variable initial saturation states (4.8-1.5) and Ca2+:SO42- ratios (3 and 0.33). Experimental durations varied between 0.5 and 190 h, while temperature (25.9-24.0 °C), pH (5.8-5.4) and ionic strength (0.6-0.5) were relatively constant. In all experiments, 20-80% of the initial dissolved Ca reservoir was precipitated. Isotopically light Ca preferentially partitioned into the precipitated gypsum; the effective isotopic fractionation factor (?44/40Cas-f = ?44/40Casolid - ?44/40Cafluid) of the experimental gypsum ranged from -2.25‰ to -0.82‰. The log weight-averaged, surface area normalized precipitation rates correlated with saturation state and varied between 4.6 and 2.0 ?mol/m2/h. The crystal size and aspect ratios, determined by SEM images, BET surface area, and particle size measurements, co-varied with precipitation rate, such that fast growth produced small (10-20 ?m), tabular crystals and slow growth produced larger (>1000 ?m), needle shaped crystals. Mass balance derived ?44Cas and ?44Cas-f, calculated using the initial fluid ?44Ca and the mass fraction of Ca removed during precipitation (fCa) as constraints, suggest that the precipitate was not always sampled homogeneously due to the need to preserve the sample for SEM, surface area, and particle size analyses. The fractionation factor (?s-f), derived from Rayleigh model fits to the fluid and calculated bulk solid, ranged from 0.9985 to 0.9988 in stirred experiments and 0.9987 to 0.9992 in unstirred experiments. The ?s-f demonstrated no clear dependence on either precipitation rate or initial saturation state in stirred reactors, but exhibited a positive dependence on rate in unstirred experiments. The differences in ?s-f between stirred and unstirred reactors, as well as a general correlation between ?s-f and crystal morphology, led us to hypothesize that growth on different crystal faces controls the isotopic composition of gypsum. We also explore the idea that speciation in solution explains the difference between experiments in which the only major difference was the Ca2+ to SO42- ratio in solution. The importance of understanding the environmental controls on the fractionation factor during mineral precipitation is highlighted in this study. The fractionation factor of gypsum precipitation near chemical equilibrium was found to be ?0.9995, rather than 1, indicating that even at near equilibrium conditions, the ?44Ca of minerals are not likely to record the ?44Ca of the solution directly. However, the measurable isotopic fractionation associated with gypsum formation does suggest that a gypsum-based proxy may be useful in constraining Ca cycling in marginal environments over geologic time scales. Model examples are provided that demonstrate how such a proxy would operate.

Harouaka, Khadouja; Eisenhauer, Anton; Fantle, Matthew S.

2014-03-01

330

EXPERIMENTAL INVESTIGATION OF DEFROST USING WARM LIQUID REFRIGERANT  

Science.gov (United States)

This paper reports the results from laboratory tests of a low-temperature supermarket refrigeration system with two open and two reach-in display cases. Tests were performed at condensing temperatures ranging from 10 to 40 C and at an evaporating temperature of -34 C. The perfo...

331

Numerical and experimental investigation of a rockfall drapery system  

Science.gov (United States)

Rockfalls represent a significant hazard to people and infrastructures in steep terrain, should it be a mountainous region, a quarry, or a mine. Although rockfall occurrences cannot be totally eliminated, it is possible to reduce the risk by deploying effective rockfall protective systems such as metallic wire mesh draperies. This work focuses on the performance of a simple drapery system with a double-twisted hexagonal wire mesh. Numerical modelling and experimental investigations have been performed. The main objective of the work is the residual hazard assessment in conjunction with such a system since blocks can still detach between the installed drapery and the rock surface. First, the numerical model for the drapery mesh and the rock slope is presented. Following the approach by Bertrand et al. [1], a discrete element model of a hexagonal wire mesh has been implemented into the open-source framework YADE [4]. The mesh is discretised by a set of spherical particles which interact remotely (i.e. interactions between the particles exist without direct contact) and are located at the physical nodes of the mesh. The rock slope is represented by triangular elements which have been generated on the basis of a point cloud representation of the rock slope. The slope is assumed to be rigid and energy dissipation on the slope during rock impact is considered via friction and viscous damping. Second, results of field tests carried out at a mine in New South Wales (Australia) are presented [3]. Concrete blocks with shapes according to EOTA [2] were released from the top of a highwall. The tests were carried out on two different sections of the highwall: the first section had a drapery system installed whereas the second section had no protective system installed. In the first section, the blocks were released between the rock surface and the mesh drapery. The 3D block trajectories were recorded by using two stereo pairs of synchronised high speed cameras. The collected data has then been used to calibrate and validate the numerical model. Finally, some remarks on the final residual hazard assessment will be given by showing some capabilities of the developed numerical model. Acknowledgments: The authors gratefully acknowledge the financial support of the Australian Coal Association Research Program (ACARP).

Thoeni, K.; Giacomini, A.; Lambert, C.; Sloan, S. W.

2012-04-01

332

Experimental investigation of gas storage properties of black shales  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In exploration for shale gas, reliable estimations of Gas-In-Place (GIP) and portion of technically recoverable resource pose a challenging task. Improvement of our understanding of gas stogare capacity of carbonaceous shales and its evolution during geological history requires carefully designed experiments to obtain reliable experimental data. Moreover, the experimental conditions have to cover a range representative of the in-situ reservoir conditions. This thesis, which was conducted duri...

Gasparik, Matus

2013-01-01

333

[Law, guidelines and standards relevant to laboratory animals and animal experimentation].  

Science.gov (United States)

Presently available laws guidelines and standards relevant to laboratory animals and animal experimentation are reviewed. In Japan there exist Animal Protection and Management Act, and the Guideline for Animal Care and Management which was later prepared in accordance with the former act. These are comparable in quality to those seen in foreign countries such as the Cruelty to Animals Act of Great Britain or the Animal Welfare Act of U.S.A. As for laboratory animals, however, only basic matters appear there, and that is why the Japanese National Academy of Science in 1980 proposed legislation of a guideline for animal experimentation to the government. It is awaited to legislate sooner the one comparable to the Guidelines for the Regulation of Animal Experimentation prepared by ICLA in 1974. Other laws and regulations referred and discussed here are: *standards and guidelines for breeding, care and management of laboratory animals *veterinary laws and regulations which should be referred when domestic or wild animals are to be used for experiments *laws and regulations for general housing construction and environmental protection *regulations for particular experiments where radioisotopes, microbial infections or recombinant DNA are in use PMID:7184424

Takagaki, Y

1982-04-01

334

Numerical and experimental investigation of leaks in viscoelastic pressurized pipes  

Directory of Open Access Journals (Sweden)

Full Text Available This paper extends the analysis concerning the importance in numerical models of unsteady friction and viscoelasticity to transients in plastic pipes with an external flow due to a leak. In fact recently such a benchmarking analysis has been executed for the cases of a constant diameter pipe (Duan et al., 2010, a pipe with a partially closed in-line valve (Meniconi et al., 2012a, and a pipe with cross-section changes in series (Meniconi et al., 2012b. The analysis is based on laboratory tests carried out at the Water Engineering Laboratory (WEL of the University of Perugia, Italy, and numerical experiments by means of different 1-D numerical models. The results show that it is crucial to take into account the viscoelasticity to simulate the main characteristics of the transients, also in the case of a damaged pipes.

S. Meniconi

2012-09-01

335

Experimental investigation of interface states in photonic crystal heterostructures.  

Science.gov (United States)

Optical Tamm states, a kind of interface modes, are also called Tamm plasmon-polaritons. They are experimentally observed in photonic heterostructures based on microstrip transmission lines. The position of optical Tamm states can be designed exactly under effective impedance match and effective phase shift match conditions. Our results show that the photonic band gaps can have the effect of negative-permittivity or negative-permeability media in constructing the interface modes. The simulations and experimental results agree with each other quite well. PMID:18850962

Guo, Jiyong; Sun, Yong; Zhang, Yewen; Li, Hongqiang; Jiang, Haitao; Chen, Hong

2008-08-01

336

Experimental Investigation of Aerodynamic Instability of Iced Bridge Cable Sections  

DEFF Research Database (Denmark)

The accretion of ice on structural bridge cables changes the aerodynamic conditions of the surface and influences hence the acting wind load process. Full-scale monitoring indicates that light precipitation at moderate low temperatures between zero and -5°C may lead to large amplitude vibrations of bridge cables under wind action. This paper describes the experimental simulation of ice accretion on a real bridge cable sheet HDPE tube segment (diameter 160mm) and its effect on the aerodynamic load. Furthermore, aerodynamic instability will be estimated with quasi-steady theory using the determined load coefficients and experimental simulation on a 1DOF elastically suspended cable section.

Koss, Holger; Lund, Mia Schou MØller

2013-01-01

337

Testing geochemical models of bentonite pore water evolution against laboratory experimental data  

Science.gov (United States)

The determination of a bentonite pore water composition and understanding its evolution with time underpins many radioactive waste disposal issues, such as buffer erosion, canister corrosion, and radionuclide solubility, sorption, and diffusion, inter alia. Previous modelling approaches have tended to ignore clay dissolution-precipitation reactions, a consequence of which is that montmorillonite is theoretically preserved indefinitely in the repository system. Here, we investigate the applicability of an alternative clay pore fluid evolution model, that incorporates clay dissolution-precipitation reactions as an integral component and test it against well-characterised laboratory experimental data, where key geochemical parameters, Eh and pH, have been measured directly in compacted bentonite. Simulations have been conducted using different computer codes (Geochemist’s Workbench, PHREEQC, and QPAC) to test the applicability of this model. Thermodynamic data for the Gibb’s free energy of formation of MX-80 smectite used in the calculations were estimated using two different methods (‘Polymer’ and ‘Vieillard’ Models). Simulations of ‘end-point’ pH measurements in batch bentonite-water slurry experiments showed different pH values according to the complexity of the system studied. The most complete system investigated revealed pH values were a strong function of partial pressure of carbon dioxide, with pH increasing with decreasing PCO 2 (with log PCO 2 values ranging from -3.5 to -7.5 bars produced pH values ranging from 7.9 to 9.6). A second set of calculations investigated disequilibrium between clay and pore fluid in laboratory squeezing cell tests involving pure water (pH = 9.0) or a 1 M NaOH solution (pH = 12.1). Simulations carried out for 100 days (the same timescale as the experiments) showed that smectite remained far from equilibrium throughout, and that the lowering of pH due to smectite hydrolysis was trivial. However, extending the duration of the simulations to that required for clay-fluid equilibrium, necessitated timescales of 7 and 65 years for pure water and 1 M NaOH, respectively, but again produced relatively minor reduction in pH (in the order of 0.1-0.2 pH units). If the (equilibrium) precipitation of secondary minerals was included in the simulations, then not only was the clay-fluid equilibration period extended dramatically (from 7 to 360 years for pure water, and from 65 to 2600 years for 1 M NaOH), but concomitant changes in pH were significant, decreasing from 9.0 to 8.6 (pure water) and from 12.1 to 9.0 (1 M NaOH). Repetition of these latter calculations using an alternative method for ?Gf0 smectite produced an increase in equilibration time for reaction with 1 M NaOH from 2600 to 5000 years, highlighting the potential effects of the uncertainty in thermodynamic data for smectite. A final set of calculations was carried out to investigate both the time- and space-dependent variations in pore fluid composition in laboratory in-diffusion experiments conducted for over 1200 days, initially with pure water and ‘spiked’ after 271 days with a Na-Ca-OH-Cl solution (pH = 11.7). Here, the sensitivity of the results to both variations in a number of parameters/conditions (porosity, reaction rate of secondary minerals, the degree of mixing of the external fluid reservoirs in the experiments, the effective diffusion coefficient) and the inclusion/exclusion of key processes (clay hydrolysis, secondary mineral precipitation, ion exchange, clay edge protonation-deprotonation reactions) was investigated. These calculations confirmed that smectite dissolution-precipitation reactions alone have an insignificant impact upon pH buffering over laboratory timescales and that the pH buffering observed is most likely controlled by clay protonation-deprotonation reactions, and kinetic secondary mineral (brucite + tobermorite) precipitation. Ion exchange reactions were found to have little effect on pH. Alternative data for the kinetic dissolution of smectite produced no observable differences, and

Savage, David; Arthur, Randy; Watson, Claire; Wilson, James; Strömberg, Bo

338

A numerical and experimental investigation of ``inverse'' triple flames  

Science.gov (United States)

Tribrachial or triple flames represent a class of partially premixed flames that generally contain three spatially distinct but synergistically coupled reaction zones, namely a rich premixed, a lean premixed, and a nonpremixed reaction zone. The generally considered flow arrangement for burner-stabilized triple flames involves a rich mixture issuing from a central port and a lean mixture from two outer ports, which we call a reference configuration (RC). Herein, we examine an inverse configuration (IC) in which a fuel-lean stream is flanked by two fuel-rich streams. The reaction zone topology in this configuration is richer and more complex compared to that in a RC flame. A numerical-experimental investigation is conducted to characterize the fundamental differences and similitude between the RC and IC methane-air triple flames in both spatial and mixture fraction based coordinates. The detailed structure of IC triple flames and their response to variations in the rich and lean equivalence ratios are examined. Finally, the transient behavior of the flames in both configurations is described. The IC and RC flames have markedly different spatial structures. In the inverse configuration, the global flame contains five reaction zones. The predicted and measured topologies of the various reaction zones are in excellent agreement. The modified mixture fraction (?) is found to be effective in characterizing the structure of both RC and IC flames. The scalar profiles in terms of ? clearly illustrate the similitude between the two flames. The three reaction zones in the RC flame have a structure that is similar to that of the corresponding five reaction zones of the IC flame. The two nonpremixed (or the two rich premixed reaction zones) in the IC flames are not differentiated in terms of ?. Both the flames are subjected to a buoyancy-induced instability at normal gravity that generates large vortex structures, which cause the reaction zones to flicker. The flame-vortex interaction is initiated in the nonpremixed reaction zone for the IC flame and in the lean premixed reaction zone for the RC flame. Consequently, the IC flame flickers with higher amplitude but lower frequency as compared to the RC flame. There is good agreement between the measured and predicted flickering frequencies for the two flames. As ?rich is increased, the height of the two rich premixed reaction zones in the IC flames increases, their tips open, and the chemical activity in these zones decreases. While the oscillation frequency is essentially constant, the oscillation amplitude increases as ?rich is increased. The effect of increasing ?lean is to enhance chemical activity in the lean premixed zone. However, the two rich premixed zones and the outer nonpremixed zone are relatively unaffected by variations in ?lean. The oscillation amplitude and frequency also remain unaffected by variations in ?lean.

Aggarwal, Suresh K.; Puri, Ishwar K.; Qin, Xiao

2001-01-01

339

Experimental investigation of reinforced concrete behaviour due to impact load  

International Nuclear Information System (INIS)

First experimental results, obtained from tests performed on reinforced concrete beams, simply supported and loaded at the middle of span width, show a significant influence of deflection velocity on the ultimate deflection which increases considerably with the growth of deflection velocity. The deflection velocity reached more than 3 m/s, the strain rate in the lower reinforcement bars about 2 s-1. (orig.)

340

Experimental investigations on vessel-hole ablation during severe accidents  

International Nuclear Information System (INIS)

formed at RIT/NPS were used to validate component physical models of the HAMISA code. It is believed that the hole ablation phenomenology is quite well understood. Detailed description of experiments and experimental data, as well as results of analyses are provided in the appendixes

 
 
 
 
341

High-temperature electrolysis for large-scale hydrogen production from nuclear energy : experimental investigations  

Energy Technology Data Exchange (ETDEWEB)

There is a significant interest in developing hydrogen as a second energy carrier for the non-electrical energy market. The Idaho National Laboratory (INL) is studying the feasibility of using solid-oxide-based electrolysis cell technology for high-temperature electrolysis of steam for large scale hydrogen production. The INL is also examining the simultaneous electrolysis of steam and carbon dioxide for syngas (hydrogen/carbon monoxide mixture) production. This technology provides a carbon neutral means of producing syngas while consuming carbon dioxide, when linked to a nuclear power source. This paper presented a summary of the INL/Ceramatec experimental activities to date on high temperature electrolysis for hydrogen and syngas production, with facility descriptions and future plans. The scope of the experimental investigations at the INL was described and included single button cell tests, multi-cell stacks, and multi-stack systems. Sample experimental results were provided that summarized electrolysis performance at various temperatures, gas mixtures, and electrical settings. It was concluded that high temperature electrolysis is a promising technology for efficient large-scale production of hydrogen and/or syngas. 7 refs., 1 tab., 16 figs.

Stoots, C.M.; O' Brien, J.E.; Condie, K.G. [Idaho National Laboratory, Idaho Falls, ID (United States); Hartvigsen, J.J. [Ceramatec Inc., Salt Lake City, UT (United States)

2009-07-01

342

Experimental methods for investigations on internal fuel rod chemistry of light water reactor fuels  

International Nuclear Information System (INIS)

For studies in fuel rod internal chemistry special experimental procedures are needed in order to obtain results which are of real value for the improvement of knowledge in this field. Some investigation techniques are described which have been developed in KWU radiochemistry and fuel development laboratories. A part of them is directed towards the determination of migration and distribution of fission products (especially Cs and I) in LWR fuel. With heating experiments of mock-up materials radiotracers or short-term irradiations are used and fission product distribution is measured by micro ? scanning. From spent fuels microsamples are taken at definite locations; analysis is performed by ? spectrometry and neutron activation analysis. Fission product escape from defective fuel rods during power reactor operation is studied by radiochemical coolant analysis. Finally, O/M ratio of spent oxide fuel is analyzed by controlled-potential coulometry. (orig.)

343

Facts and Figuring: An Experimental Investigation of Network Structure and Performance in Information and Solution Spaces  

CERN Document Server

Using data from a large laboratory experiment on problem solving in which we varied the structure of 16-person networks we investigate how an organization's network structure may be constructed to optimize performance in complex problem-solving tasks. Problem solving involves both search for information and search for theories to make sense of that information. We show that the effect of network structure is opposite for these two equally important forms of search. Dense clustering encourages members of a network to generate more diverse information, but it also has the power to discourage the generation of diverse theories: clustering promotes exploration in information space, but decreases exploration in solution space. Previous research, tending to focus on only one of those two spaces, had produced inconsistent conclusions about the value of network clustering. By adopting an experimental platform on which information was measured separately from solutions, we were able to reconcile past contradictions an...

Shore, Jesse; Lazer, David

2014-01-01

344

Numerical and experimental investigation of the 3D free surface flow in a model Pelton turbine  

Energy Technology Data Exchange (ETDEWEB)

This investigation focuses on the numerical and experimental analysis of the 3D free surface flow in a Pelton turbine. In particular, two typical flow conditions occurring in a full scale Pelton turbine - a configuration with a straight inlet as well as a configuration with a 90 degree elbow upstream of the nozzle - are considered. Thereby, the effect of secondary flow due to the 90 degree bending of the upstream pipe on the characteristics of the jet is explored. The hybrid flow field consists of pure liquid flow within the conduit and free surface two component flow of the liquid jet emerging out of the nozzle into air. The numerical results are validated against experimental investigations performed in the laboratory of the Institute of Fluid Mechanics (FLM). For the numerical simulation of the flow the in-house unstructured fully parallelized finite volume solver solver3D is utilized. An advanced interface capturing model based on the classic Volume of Fluid method is applied. In order to ensure sharp interface resolution an additional convection term is added to the transport equation of the volume fraction. A collocated variable arrangement is used and the set of non-linear equations, containing fluid conservation equations and model equations for turbulence and volume fraction, are solved in a segregated manner. For pressure-velocity coupling the SIMPLE and PISO algorithms are implemented. Detailed analysis of the observed flow patterns in the jet and of the jet geometry are presented.

Fiereder, R; Riemann, S; Schilling, R, E-mail: fiereder@lhm.mw.tum.d [Department of Fluid Mechanics, Technische Universitaet Muenchen Bolzmannstrasse 15, Garching, 85748 (Germany)

2010-08-15

345

Numerical and experimental investigation of the 3D free surface flow in a model Pelton turbine  

International Nuclear Information System (INIS)

This investigation focuses on the numerical and experimental analysis of the 3D free surface flow in a Pelton turbine. In particular, two typical flow conditions occurring in a full scale Pelton turbine - a configuration with a straight inlet as well as a configuration with a 90 degree elbow upstream of the nozzle - are considered. Thereby, the effect of secondary flow due to the 90 degree bending of the upstream pipe on the characteristics of the jet is explored. The hybrid flow field consists of pure liquid flow within the conduit and free surface two component flow of the liquid jet emerging out of the nozzle into air. The numerical results are validated against experimental investigations performed in the laboratory of the Institute of Fluid Mechanics (FLM). For the numerical simulation of the flow the in-house unstructured fully parallelized finite volume solver solver3D is utilized. An advanced interface capturing model based on the classic Volume of Fluid method is applied. In order to ensure sharp interface resolution an additional convection term is added to the transport equation of the volume fraction. A collocated variable arrangement is used and the set of non-linear equations, containing fluid conservation equations and model equations for turbulence and volume fraction, are solved in a segregated manner. For pressure-velocity coupling the SIMPLE and PISO algorithms are implemented. Detailed analysis of the observed flow patterns in the jet and of the jet geometry are presented.

346

Experimental investigations on the first Townsend coefficient in pure isobutane  

International Nuclear Information System (INIS)

In this work we present results of the first Townsend coefficient (?) in pure isobutane by measuring the current growth as a function of the electric field strength in a pulsed irradiation regime. A Resistive Plate Chamber (RPC)-like configuration was used. To validate this method, as well as to crosscheck the experimental apparatus, measurements of the ? parameter were firstly carried out with pure nitrogen and the results compared to the accurate data available in the literature. The data obtained with isobutane in a field range from 145 Td up to 200 Td were well-matched to those calculated with Magboltz versions 2.7.1 and 2.8.6. The experimental consistency of these results with other published data in the range of 550–1300 Td was very good, as demonstrated by the use of the Korff parameterization.

347

Experimental investigation on bubble characteristics entrained by surface vortex  

International Nuclear Information System (INIS)

The cover gas entrainment at the free surface of sodium coolant becomes one of the significant issues according to the compact sizing of reactor vessel in the latest reactor design. In the present study, some basic experiments for the gas entrainment due to the surface vortex were performed in order to obtain the fundamental knowledge about the entrained bubble size. Distributions of entrained bubble diameters in several experimental conditions were obtained from bubble images using an image processing technique. Velocity fields around vortices and surface dimple shapes (gas cores) due to surface vortices were measured to grasp those influences on bubble shapes. The result showed that mean equivalent diameters of bubbles were varied from 1.3 to 2.1 mm in the range of present experimental conditions. The bubble sizes were influenced by the thickness of gas core.

348

Experimental and Computational Investigations of Flow past Spinning Cylinders  

Science.gov (United States)

Experiments are performed in a low speed subsonic wind tunnel to analyze flow past spinning cylinders. The sting-mounted cylinders are oriented such that their axis of rotation is aligned with the mean flow. Data from spinning cylinders with both rear-mounted and fore-mounted stings are presented for a Reynolds numbers of up to 260000 and rotation numbers of up to 1.2 (based on cylinder diameter). Computations are performed using a two-equation turbulence model that is capable of capturing the effects of swirl and curvature. The model performance was validated with benchmark experimental flows and implemented for analyzing the flow configuration used in the experimental study. The results are analyzed and the predictive capability of the model is discussed.

Carlucci, Pasquale; Mehmedagic, Igbal; Buckley, Liam; Carlucci, Donald; Thangam, Siva

2011-11-01

349

Experimental and numerical investigation of confined coaxial turbulent jets  

International Nuclear Information System (INIS)

The present study concentrates on the turbulent mixing of a primary jet and its surrounding fluid stream in a pipe. Detailed profiles of the axial mean and rms velocities have been measured with an LDA unit. Measured spectra of the centerline axial velocity fluctuations demonstrated the presence of coherent structures with Strouhal numbers between 0.33 and 0.51. A finite-difference numerical procedure was used for the prediction of the axisymmetric elliptic flow field. The performance of a two-equation turbulence model was tested for selected sets of previous experimental data. The dominance of numerical diffusion in the present computations has been documented. A set of numerical computations which utilize the detailed inlet profiles obtained during the present experimental work were also performed. Comparison of the numerical predictions to the present measurements were found to be satisfactory. 19 references

350

Theoretical and Experimental Investigations of DNA Open States  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This research is a review and assay of literature data on the properties of DNA open states. The states result from large fluctuations of a duplex and have a great influence on a wide range of biochemical processes, including electric charge transfer in DNA. A comparative analysis of kinetic and thermodynamic experimental data on DNA open states has been performed for a wide temperature range. Apparent contradictions between the data of different experiments have been explai...

Shigaev, A. S.; Ponomarev, O. A.; Lakhno, V. D.

2014-01-01

351

Experimental investigation of the 61?+ ‘shelf' state of KCs  

Science.gov (United States)

We report the first experimental observation of the 61?+ state in the KCs molecule. Polarization labelling spectroscopy technique was applied to determine energies of about 1000 rovibrational levels in this state, most of them strongly perturbed by the neighbouring 43? state levels. The inverted perturbation approach was used to construct the irregular potential energy curve of the 61?+ state. It is compared with the recent theoretical calculations to show that Hund's coupling case (a) is proper for description of this state.

Szczepkowski, J.; Grochola, A.; Jastrzebski, W.; Kowalczyk, P.

2014-10-01

352

Experimental investigation of dynamic pressure loads during dam break  

Science.gov (United States)

The objectives of this work are to revisit the experimental measurements on dam break flow over a dry horizontal bed and to provide a detailed insight into the dynamics of the dam break wave impacting a vertical wall downstream the dam, with emphasis on the pressure loads. The measured data are statistically analyzed and critically discussed. As a result, an extensive set of data for validation of computational tools is provided.

Lobovský, L.; Botia-Vera, E.; Castellana, F.; Mas-Soler, J.; Souto-Iglesias, A.

2014-07-01

353

Experimental investigation of energy balance in plasma arc cutting process  

Science.gov (United States)

The present paper describes the power balance of the arc cutting process provided by a plasma torch with steam working medium. The work was concentrated on definition of different power terms including power input as well as effective power utilization and losses as a function of plasma gas flow rate. The work was mostly experimental. The results have shown around 20% of total available power is utilized for material cutting and removing for the studied conditions.

Kavka, T.; Tossen, S.; Maslani, A.; Konrad, M.; Pauser, H.; Stehrer, T.

2014-05-01

354

Experimental investigation of the variability of concrete durability properties  

Digital Repository Infrastructure Vision for European Research (DRIVER)

One of the main objectives of the APPLET project was to quantify the variability of concrete properties to allow for a probabilistic performance-based approach regarding the service lifetime prediction of concrete structures. The characterization of concrete variability was the subject of an experimental program which included a significant number of tests allowing the characterization of durability indicators or performance tests. Two construction sites were selected from which concrete spec...

Ai?t Mokhtar, Karim; Torrenti, Jean Michel; Benboudjema, Farid; Capra, Bruno; Carcasses, M.; Colliat, Jean-baptiste; Cussigh, Franc?ois; Larrard, Thomas; Lataste, Jf; Poyet, Ste?phane; Rougeau, Patrick; Sellier, A.; Trabelsi, A.; Turcry, Philippe

2013-01-01

355

Experimental and numerical investigations of dike-break induced flows  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Experimental model data are compared with numerical computations of dike-break induced flows, focusing on the final steady state. An idealised scale model was designed reproducing the specific boundary conditions of dike breaks. Discharges, water levels and depth profiles of horizontal velocities were recorded and validated by numerical modeling. The latter was performed by two different models solving the two-dimensional depth-averaged shallow water equations, namely a total variation dimini...

Roger, Sebastian; Dewals, Benjamin; Erpicum, Se?bastien; Schwanenberg, Dirk; Schu?ttrumpf, Holger; Ko?ngeter, Ju?rgen; Pirotton, Michel

2009-01-01

356

Experimental and computational investigations of biomass mixing and combustion processes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Biomass is considered to be a promising source of sustainable energy and consequently it is attracting more research attention. The focus of this ongoing study is on the performance of biomass combustion processes. Computational fluid dynamics (CFD) techniques are planned to simulate the combustion process in various models. This is done in parallel with experimental work to understand the mixing and combustion behaviour biomass. For this purpose CFD models based on both Euler-Lag...

Alganash, B. S.; Paul, M. C.; Watson, I. A.

2011-01-01

357

Experimental investigation of ion-implanted magnetic recording material  

International Nuclear Information System (INIS)

The structure changes in ion implanted Permalloy have been observed by reflection high energy electron diffraction and X-ray photoelectron spectrometry. Amorphous phase and metal compound are formed in the surface layer. The magnetic property, mechanical property and surface roughness of the ion implanted samples and frequency response of the ion implanted magnetic head have been measured. The experimental results show that the hardening layer could be formed on the surface of an implanted sample without any degradation of the magnetic property

358

Experimental investigations on Elastic Properties of Concrete containing Steel fibre  

Directory of Open Access Journals (Sweden)

Full Text Available this paper presents the relationship between modulus of elasticity and, modulus of rupture relationship with compressive strength of M60 concrete incorporating Steel fibre. Comparing the experimentally obtained result with the mechanical properties calculated using the recommend relationship from the various design codes. A new empirical relationship between elastic modulus, modulus of rupture and compressive strength for Steel fibre based M60 concrete is proposed.

K.Anbuvelan

2014-03-01

359

Investigations in Experimental and Theoretical High Energy Physics  

Energy Technology Data Exchange (ETDEWEB)

We report on the work done under DOE grant DE-FG02-01ER41155. The experimental tasks have ongoing efforts at CERN (ATLAS), the Whipple observatory (VERITAS) and R&D work on dual readout calorimetry and neutrino-less double beta decay. The theoretical task emphasizes the weak interaction and in particular CP violation and neutrino physics. The detailed descriptions of the final report on each project are given under the appropriate task section of this report.

Krennrich, Frank [Iowa State University

2013-07-29

360

A laboratory for investigating and monitoring the contamination of air with radioactive iodine  

International Nuclear Information System (INIS)

The paper describes a model of an isotope laboratory of 2nd class called ''A laboratory for investigating and monitoring the contamination of the air with radioactive iodine'' based on the laboratory apparatus produced in Poland and electronic apparatus manufactured by ZZUJ POLON. The scope of work and working procedures for 131I and CH3131I vapour generators are described. The determination of the efficiency of fiber filters and adsorption materials is also presented. The radiation hazard from the 131I sources during work and during a radiation accident is evaluated. (author)

 
 
 
 
361

Experimental and CFD investigation of gas phase freeboard combustion  

DEFF Research Database (Denmark)

Reliable and accurate modeling capabilities for combustion systems are valuable tools for optimization of the combustion process. This work concerns primary precautions for reducing NO emissions, thereby abating the detrimental effects known as “acid rain”, and minimizing cost for flue gas treatment. The aim of this project is to provide validation data for Computational Fluid Dynamic (CFD) models relevant for grate firing combustion conditions. CFD modeling is a mathematical tool capable of predicting fluid flow, mixing and chemical reaction with thermal conversion and transport. Prediction of pollutant formation, which occurs in small concentrations with little impact on the general combustion process is in this work predicted by a post-processing step, making it less computationally expensive. A reactor was constructed to simulate the conditions in the freeboard of a grate fired boiler, but under well-defined conditions. Comprehensive experimental data for velocity field, temperatures, and gas compositionare obtained from a 50 kW axisymmetric non-swirling natural gas fired combustion setup under two different settings. Ammonia is added to the combustion setup in order to simulate fuel-NO formation during grate firing biomass combustion conditions. The experimental results are in this work compared to CFD modeling. The modeling results show, that the CFD model captured the main features of the combustion process and flow patterns. The application of more advanced chemical reaction mechanisms does not improve the prediction of the overall combustion process, but do provide additional formation about species (especially H2 and radicals), which is desirable for post-processing pollutant formation. NO formation is post-processed using various ammonia oxidation schemes and different post-processing techniques. The results in some cases provide a reasonable agreement with the experimental data. In general the application of advanced combustion modeling and more advanced ammonia oxidation mechanisms does not improve the agreement with experimental data compared to the simple eddy dissipation (mixed is burned) approach with post processing of a global combustion mechanism. The experimental setup does however not serve as a perfect validation case. The Reynolds numbers in the system put the flow regime in the transitional region, where turbulence modeling is difficult. Furthermore, the inclined jets show an affinity towards wall attachment, the entire modeling result is very sensitive to the prediction of these jets.

Andersen, Jimmy

2009-01-01

362

Experimental Investigation of Use of Microsilica in Self Compacting Concrete  

Directory of Open Access Journals (Sweden)

Full Text Available This paper is described Project in detail and presents laboratory observation. Microsilica is used as a 10% replacement of cement by weight. Various test were conducted on fine aggregate & coarse aggregate, to determine specific gravity, bulk density, fineness modulus of aggregate, concrete mix proportion design using this parameter..For conventional concrete water cement ratio of 0.4 and for microsilica concrete is increased water contain about 20liter/m3. Water demand increases in proportion to the amount of microsilica added. Mixing the concrete and various test are conducted on fresh concrete i.e. Slump flow, V- Funnel, L-Box, U-Box and result are obtained. Using this concrete cube specimen are cast for testing different hardened properties of concrete. i.e. 3 Days, 7 Days, 14 Days, 28 Days Compressive strength of concrete.

Mr.Ashok P. Kalbande

2012-05-01

363

Experimental and climical investigations of a TSH radioimmunoassay  

International Nuclear Information System (INIS)

The system hypothalamus-pitnitary-thyroid was studied in 427 patients by radioimmunological TSH determination prior to i.v. injection of 600 ?g of synthetic TSH and 30 min p.i. Different commercial TSH test kits were used. The RIA was found to be a sensitive indicator of the functional state of the system. Higher accuracy can be achieved by observing certain criteria. The TSH-RIA is a valuable tool for diagnosis and therapy control of thyroid diseases. With some slight methodological modifications, it has become part of the routine programme of the Giessen thyroid laboratory. The RIA is best suited for early detection of disturbances in the pitnitary-thyroid system; it is less efficient in course control of thyroid diseases. It can be carried out within 30 minutes and, except for two withdrawals of blood, imposes no strain on the patient. (orig./MG)

364

Interleaved Carbon Minibeams: An experimental Method of Radiosurgery Developed at Brookhaven National Laboratory  

International Nuclear Information System (INIS)

Despite recent major innovations in radiation therapy and radiosurgery, there are limitations in treating certain tumors and neurological targets while assuring acceptable damage to the surrounding tissues. These encompass certain tumors in the brain, spinal cord, spinal column, and head-and-neck. This paper describes an experimental radiosurgery, “Interleaved carbon minibeams”1 being developed at the NASA Space Radiation Laboratory (NSRL), Brookhaven National Laboratory (BNL). The method uses arrays of parallel, thin (?0.3 mm incident beam thickness) planes of carbon ion beams, called carbon minibeams, that “interleave” to produce a solid radiation field at the target . Therefore, the method delivers a solid field of carbon radiation to the target while exposing the surrounding tissues to single arrays of carbon minibeams, which are well tolerated by tissues

365

Shock induced response of structural systems analytical and experimental investigations  

International Nuclear Information System (INIS)

This contribution refers to the behaviour of reinforced concrete structures impacted by deformable missiles. The difference with hard missile impact problems, about which generally more knowledge exists, are point out. Structural response effects beyond the immediate contact face vicinity, beyond the local load introduction zone - i.e. effects of punching shear, of bending, of vibration transmission etc. - are emphasized. Two- and three-dimensional analytical approaches verified by experimental evaluations are discussed, and typical phenomena of the behaviour of reinforced concrete structures subjected to impact loads are demonstrated. (Author)

366

Experimental investigation of magnetic anisotropy in spin vortex discsa)  

Science.gov (United States)

We present experimental 2D vector vibrating sample magnetometer measurements to demonstrate the shape anisotropy effects occurring in micrometer-diameter supermalloy spin vortex discs. Measurements made for different disc sizes and orientations confirm the out-of-plane susceptibility is several orders of magnitude smaller than the in-plane susceptibility. These results validate with a high certitude that spin vortices with high diameter to thickness ratio retain in-plane-only magnetization, even when subjected to fields in the out-of-plane direction. These results contribute to further computational simulations of the dynamics of spin vortex structures in colloidal suspensions where external fields may be applied in any arbitrary direction.

Garraud, N.; Arnold, D. P.

2014-05-01

367

The experimental investigation of bounce characteristics of ACV responsive skirt  

Science.gov (United States)

This paper presents some experimental results on the bounce characteristics of the bag-finger responsive skirt and on skirt frequency response under cushion pressure excitation obtained in a large-scale box facility. The influence of some parameters on the amplitude and frequency of the skirt bounce motion and the amplitude of the cushion pressure oscillation were explored, and the corresponding bounce boundary curves are given. Some interesting nonlinear phenomena related to the skirt instability in the time domain response are presented. The mechanism for skirt bounce and the important parameters affecting skirt dynamic stability are examined, and some means for eliminating skirt bounce are introduced.

Zhou, W. L.; Ma, T.

368

Numerical and experimental investigation of thermal louvers for space applications  

Directory of Open Access Journals (Sweden)

Full Text Available Thermal louvers, using movable or rotating shutters over a radiating surface, have gained a wide acceptance as highly efficient devices for controlling the temperature of a spacecraft. This paper presents a detailed analysis of the performance of a rectangular thermal louver with movable blades. The radiative capacity of the louver, determined by its effective emittance, is calculated for different values of the blades opening angle. Experimental results obtained with a prototype of a spacecraft thermal louver show good agreement with the theoretical values.

Issamu Muraoka

2001-01-01

369

A novel linear switched reluctance motor : Investigation and experimental verification  

Directory of Open Access Journals (Sweden)

Full Text Available A novel stator geometry for a linear switched reluctance motor (LSRM that improves the force profile is presented inthis paper. In the new geometry, pole shoes are affixed on the stator poles. Static characteristics for the proposed structurehave been highlighted using two dimensional (2-D finite element analyses (FEA. A detailed sensitivity analysis of the effectof several geometrical parameters on the performance of the proposed LSRM is presented. Further, motor performance forvariable load conditions is discussed. The 2-D FEA results and the experimental results of this paper prove that LSRMs areone of the strong candidates for linear propulsion drives.

Rengasamy Arumugam

2011-02-01

370

Experimental investigation of magnetic anisotropy in spin vortex discs  

Energy Technology Data Exchange (ETDEWEB)

We present experimental 2D vector vibrating sample magnetometer measurements to demonstrate the shape anisotropy effects occurring in micrometer-diameter supermalloy spin vortex discs. Measurements made for different disc sizes and orientations confirm the out-of-plane susceptibility is several orders of magnitude smaller than the in-plane susceptibility. These results validate with a high certitude that spin vortices with high diameter to thickness ratio retain in-plane-only magnetization, even when subjected to fields in the out-of-plane direction. These results contribute to further computational simulations of the dynamics of spin vortex structures in colloidal suspensions where external fields may be applied in any arbitrary direction.

Garraud, N., E-mail: ngarraud@ufl.edu; Arnold, D. P. [Department of Electrical and Computer Engineering, University of Florida, Gainesville, Florida 32611 (United States)

2014-05-07

371

Experimental investigations on the four-loop test facility ROCOM  

International Nuclear Information System (INIS)

For the analysis of the core behaviour during boron dilution transients and main steam line breaks, coupled neutron kinetic/thermal hydraulic codes are necessary. These codes must contain models of the coolant mixing on its way from the inlet nozzles to the core entrance, because the reactivity insertion strongly depends on the distribution of temperature and boron concentration at the core inlet. To model the coolant mixing the ROCOM test facility was built, a fluid dynamic 1:5 scaled model of the Konvoi reactor. The experimental results at steady state flow conditions are presented in a survey form. (orig.)

372

An experimental investigation of pulsed multichannel discharge across solid insulators  

Science.gov (United States)

An experimental study of pulsed surface flashover across a solid insulator in a vacuum is reported, with application of fast impulse voltages of a few tens of ns rise time and a few microsec tail time. Following the flashover voltage experiments, no visible degradation of the surface was found for the BaTiO3 sample, whereas for the TiO2 sample a distinct track mark could be seen where the flashover occurred. Three schemes for obtaining multichannel discharges were studied for plexiglass specimens, and results showed the number of shots to decrease as the number of channels increased.

Lakdawala, V. K.; Ko, S. T.; Lee, J. H.

1985-01-01

373

Methodic aspects of experimental investigation of optimality of heterogeneous shields  

International Nuclear Information System (INIS)

On the basis of the effective neutron and gamma radiation attenuation constants and the concept of efficiency function the possibility to apply the experimental variational method for optimization of multy-layered biological shields is proved. The dependence of the flux functional and the efficiency function on the interface coordinates is derived. The practical application of the method for analyzing both two- and multy-layered specific shields with and without account for the neutron-induced secondary gamma radiation is discussed. It is concluded that the method proposed provides one with a useful fool for transferring the results of simulating experiments on designed physical facilities

374

Experimental investigation of magnetic anisotropy in spin vortex discs  

International Nuclear Information System (INIS)

We present experimental 2D vector vibrating sample magnetometer measurements to demonstrate the shape anisotropy effects occurring in micrometer-diameter supermalloy spin vortex discs. Measurements made for different disc sizes and orientations confirm the out-of-plane susceptibility is several orders of magnitude smaller than the in-plane susceptibility. These results validate with a high certitude that spin vortices with high diameter to thickness ratio retain in-plane-only magnetization, even when subjected to fields in the out-of-plane direction. These results contribute to further computational simulations of the dynamics of spin vortex structures in colloidal suspensions where external fields may be applied in any arbitrary direction

375

Experimental investigation of the transverse SBS excitation in anisotropic crystals  

International Nuclear Information System (INIS)

One of the factors which should be taken into account in creating high-power broad-aperture neodymium laser facilities is the possibility of generating the backward and transverse stimulated Brillouin scattering(SBS) in optical elements of the facility. Here, transverse SBS characteristics of the KDP crystal were determined by the method of SBS generation excitation in the transverse resonator. Fused silica was utilized as the test medium. Experimental oscillograms of Stokes pulses were processed by the method of pulse form approximation using the four-parametric function of time

376

Experimental Investigation of Ionization Waves in Fast Pulsed Capillary Discharges  

International Nuclear Information System (INIS)

Previous investigations show that the electric breakdown process in shielded capillary discharges with a hollow cathode geometry is characterized by the propagation of an anode directed high speed ionization wave (HSIW). To further investigate HSIW assisted capillary discharges with negative polarity, we have performed detailed experiments in argon, at pressures between 0.2 and 1.0 Torr. For these pressures, a characteristic ionization wave speed in the 0.1-3.0 x 107 m/s range is observed. The speed and amplitude of the wave are seen to decrease as the wave propagates along the capillary axis. As a result of these investigations, the role of the hollow cathode electron beams is clearly identified and the HSIW is established as the dominant mechanism for electric breakdown in low pressure capillary discharges, sharing most of the features previously observed in much larger coaxial discharge devices

377

Sediment transport during flash flood events on an intermittent river: an experimental laboratory study.  

Science.gov (United States)

Flash floods have a number of impacts on the water quality of river systems because the later is the resultant of pollutant input into the river and its transformation along its course. In the case of intermittent rivers this impact is increased by the long drought periods that usually precede such floods. Indeed, the pollutants are known to accumulate in the dry river sediments during the drought period and are flushed away by the first floods. The Vène, a small experimental catchment (67 km²) located in southern France is a perfect example of this type of behavior. The field data collected on the catchment since 1994 through routine and flood monitoring clearly show an increase in suspended solids and nutrient concentrations during flash floods. However, the hydraulic conditions which lead to the triggering of sediment movement and re-suspension are not known. The aim of this study is to investigate sediment re-suspension mechanisms by reproducing the dynamics of sediment movement during flash floods at the reach scale in controlled laboratory conditions. A rectangular flume (6m*0.29m*0.18m) is used as a scale model of a 1 km reach. Variable flow conditions can be set in the flume through a quarter turn valve. Discharge values are monitored using an electromagnetic flow meter and water velocity measurements are carried out in the flume using a Pitot probe coupled to a digital manometer. Dynamic similarity is imposed between the reach and the flume i.e. the reach's Froude number is set equal to that of the flume. The reach's rating curve is used to determine a set of experimental height and flow values for the flume. For each test, the slope of the flume is modified in order to respect the rating curve. The flume's bed is reconstructed by respecting the similarity ratios determined previously using glass micro beads to represent its sediments. Various tests are carried out in steady-state conditions for different discharge values. In transient conditions, the observed hydrograph's rising times are used to calculate corresponding flow durations in the flume. The entire water column is sampled for sediment mass at the outlet of the flume using very fine time steps. The measured velocity gradients are used to calculate the corresponding shear stress values at the bottom of the water column. Relationships between discharge, rising time, shear stress, and sediment mass dynamics are analyzed. The preliminary results highlight the role of turbulent processes on sediment movement and re-suspension. However, the results are extremely sensitive to the sediment arrangement pattern i.e. to bed morphology. Although the Pitot probe has clear advantages in terms of ease of use and price, the corresponding measurements do not allow an accurate determination of shear stress values. The experimental protocol is currently being enhanced to solve this problem by seeking alternate measurement devices.

Moustabachir, H.; Chahinian, N.; Romieux, N.; Vittenet, J.; Gayrard, E.; Tournoud, M. G.

2009-04-01

378

Water Sloshing in Rectangular Tanks – An Experimental Investigation & Numerical Simulation  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents the steps involved in designing a test rig to study water sloshing phenomenon in a 560 x 160 x 185 mm PVC rectangular container subjected to sudden (impulsive impact. The design encompasses the construction of the testing facility and the development of a proper data acquisition system capable of capturing the behavior of pre- and post impact water motion inside the tank. Fluid motion was recorded using a video camera for flow visualization purpose. Two water levels of 50 and 75% full as well as two driving weights of 2.5 and 4.5 kg were used. The experimental study was supplemented by a computational fluid dynamics study to mimic the fluid motion inside the tank. Examination of CFD capability to predict the behavior of the free surface of the fluid during the container initial motion and after impact is the focus of this paper. The flow fields, obtained using the numerical code, are in reasonable agreement with those from experiments. Both experimental and numerical results indicated the presence of a single traveling wave before impact, contrary to what was observed in previous studies.

Abdennour C Seibi

2009-05-01

379

Control strategies for friction dampers: numerical assessment and experimental investigations.  

Directory of Open Access Journals (Sweden)

Full Text Available The use of friction dampers has been proposed in a wide variety of mechanical systems for which it is not possible to apply viscoelastic materials, fluid based dampers or others viscous dampers. An important example is the application of friction dampers in aircraft engines to reduce the blades vibration amplitudes. In most cases, friction dampers have been studied in a passive way, however, a significant improvement can be achieved by controlling the normal force in the dampers. The aim of this paper is to study three control strategies for friction dampers based on the hysteresis cycle. The first control strategy maximizes the energy removal in each harmonic oscillation cycle, by calculating the optimum normal force based on the last displacement peak. The second control strategy combines the first one with the maximum energy removal strategy used in the smart spring devices. Finally, is presented the strategy which homogenously modulates the friction force. Numerical studies were performed with these three strategies defining the performance metrics. The best control strategy was applied experimentally. The experimental test rig was fully identified and its parameters were used for the numerical simulations. The obtained results show the good performance for the friction damper and the selected strategy.

Coelho H.T.

2014-01-01

380

An experimental investigation of post dryout heat transfer  

International Nuclear Information System (INIS)

The present report contains the results of post-dryout measurements which have been carried out in the Department of Nuclear Reactor Engineering at the Royal Institute of Technology. More than 15000 heat transfer coefficients were obtained for electrically heated round tubes in the post-dryout regime, covering the following ranges of parameters: Heated length L=7000 mm, Inner diameter d(sub)i=14.90, 10.00 and 24.69 mm, Inlet subcooling ?t(sub)i=10degreeC, Pressure p=30-205 bar, Mass velocity G=500-3000 kg/m2s, Heat flux g/A=9-125 W/cm2, PDO steam quality x(sub)PDO=0.03-1.66. A brief description of the experimental equipment is given as well as a table containing the experimental results. The data have been stored on a tape which is available at the department of Nuclear Reactor Engineering at the Royal Institute of Technology. (author)

 
 
 
 
381

Experimental investigation two phase flow in direct methanol fuel cells  

International Nuclear Information System (INIS)

Direct methanol fuel cells (DMFC) have received many attentions specifically for portable electronic applications since it utilize methanol which is in liquid form in atmospheric condition and high energy density of the methanol. Thus it eliminates the storage problem of hydrogen. It also eliminates humidification requirement of polymeric membrane which is a problem in PEM fuel cells. Some electronic companies introduced DMFC prototypes for portable electronic applications. Presence of carbon dioxide gases due to electrochemical reactions in anode makes the problem a two phase problem. A two phase flow may occur at cathode specifically at high current densities due to the excess water. Presence of gas phase in anode region and liquid phase in cathode region prevents diffusion of fuel and oxygen to the reaction sites thus reduces the performance of the system. Uncontrolled pressure buildup in anode region increases methanol crossover through membrane and adversely effect the performance. Two phase flow in both anode and cathode region is very effective in the performance of DMYC system and a detailed understanding of two phase flow for high performance DMFC systems. Although there are many theoretical and experimental studies available on the DMFC systems in the literature, only few studies consider problem as a two-phase flow problem. In this study, an experimental set up is developed and species distributions on system are measured with a gas chromatograph. System performance characteristics (V-I curves) is measured depending on the process parameters (temperature, fuel ad oxidant flow rates, methanol concentration etc)

382

Experimental and numerical investigations on microstereolithography of ceramics  

Science.gov (United States)

Microstereolithography (?SL) uses laser light to solidify UV-curable resin mixed with concentrated ceramic powders. During the ?SL process, the light scattering from the particle suspension is found to significantly influence the fabrication resolution in both lateral and depth dimensions which are critical for the complex three-dimensional (3D) microfabrication. In this work, we performed Monte Carlo simulations and experimental studies to understand the detailed microscale optical scattering, chemical reaction (polymerization), and their influence on critical fabrication parameters. As a result, it was found that due to the scattering, the fabricated line is wider in width and smaller in depth compared with polymeric fabrication at the same condition. The doping technique that we used substantially reduced the light scattering, which in turn enhanced the fabrication precision and control. In addition, the experimental values of curing depth and radius agreed reasonably well with the theoretical modeling. When a laser beam was focused to the diffraction limit, an ultimate linewidth resolution with ceramic ?SL was found at about 2.6 ?m.

Sun, C.; Zhang, X.

2002-10-01

383

Investigating Climate Change and Reproduction: Experimental Tools from Evolutionary Biology  

Directory of Open Access Journals (Sweden)

Full Text Available It is now generally acknowledged that climate change has wide-ranging biological consequences, potentially leading to impacts on biodiversity. Environmental factors can have diverse and often strong effects on reproduction, with obvious ramifications for population fitness. Nevertheless, reproductive traits are often neglected in conservation considerations. Focusing on animals, recent progress in sexual selection and sexual conflict research suggests that reproductive costs may pose an underestimated hurdle during rapid climate change, potentially lowering adaptive potential and increasing extinction risk of certain populations. Nevertheless, regime shifts may have both negative and positive effects on reproduction, so it is important to acquire detailed experimental data. We hence present an overview of the literature reporting short-term reproductive consequences of exposure to different environmental factors. From the enormous diversity of findings, we conclude that climate change research could benefit greatly from more coordinated efforts incorporating evolutionary approaches in order to obtain cross-comparable data on how individual and population reproductive fitness respond in the long term. Therefore, we propose ideas and methods concerning future efforts dealing with reproductive consequences of climate change, in particular by highlighting the advantages of multi-generational experimental evolution experiments.

Oliver Y. Martin

2012-09-01