bluuebunny/crossref_metadata_2025 huggingface dataset:
Quality Assurance in the ITER Construction
Authors: Park Sungkook , Sands David , Alejaldre Carlos
Published: April 2011

The ITER project is basically an engineering and construction project in order to build the ITER machine which is a scientific experimental fusion device. The seven members of the project have all created legal entities called Domestic Agencies to provide in-kind contributions to the ITER Organization (IO) for the supply of components which are manufactured by their suppliers. According to ITER agreement and due to nuclear safety involved in the fusion process, the project requires a license from the French Nuclear Safety Authority. One of nuclear safety regulations is the French Quality Order. The IO has established a Quality Assurance Program for the construction of the ITER machine to meet the requirements of the Order and to ensure that ITER activities are performed to achieve the safety and performance objectives of the ITER machine. The requirements in the program shall be followed by all performers involved in the project not only the IO, but DAs and their suppliers and subcontractors. This paper represents the quality requirements from the Order, and roles and responsibilities between each performer involved in the project. The paper also shows the main characteristics of the ITER Quality Assurance Program ensuring that all activities performed for the project conform to established and documented requirements.
The Progress of R&Ds for JSFR Innovative Technologies
Authors: Kikuchi Hirohiko , Mochida Haruo , Ide Akihiro , Iitsuka Toru , Hayafune Hiroki
Published: April 2011

This paper shows research and developments (R&Ds) programs for innovative technology about main components of Japan Sodium-cooled Fast Reactor (JSFR). JSFR is an advanced loop type Sodium-cooled Fast Reactor. Innovative technologies will be adopted in the JSFR for economic competitiveness, enhancing reliability, and safety. The concept of JSFR is to aim at reducing an amount of commodity, by reduction in the number of cooling loops, an adoption of high-chromium steel with low thermal expansion coefficient and high-temperature strength, and shortening a piping length by connection of outlet/inlet piping to an upper part of the reactor vessel, as well as the integration of a pump into IHX. Further, at secondary cooling system, higher reliable Steam Generator with double-walled straight tube using high-chromium steel is adopted. In the Fast Reactor Cycle Technology Development (FaCT) project, a design for JSFR has been executed along design categories such as core design, reactor system, heat transport system, safety design, etc., with corresponding R&Ds.
Reflood Oxidation Model Based on Reaction-Diffusion Equations
Authors: He Xiaoqiang , Yu Hongxing , Jiang Guangming
Published: April 2011

An important accident management measure in PWRs is the injection of water to cool the degrading core, in which process the temperature and hydrogen production will significantly increase due to enhanced oxidation after shattering of zircaloy fuel rod. This phenomenon can be described by Zr oxidation model and shattering model. The process of Zr oxidation is usually represented by parabolic rate correlations. But, after consumption of primary β-Zr, or in steam starvation conditions, the correlation approach is restricted. Besides, using this approach, it is impossible to obtain detailed oxygen distribution in the cladding which impacts the detailed mechanical behavior, such as shattering of cladding. The shattering of cladding is mainly contributed by deep cracks penetrating the oxide layer as well as the adjacent metallic. In SCDAP/RELAP5, the shattering criterion is relevant to the thickness of β-Zr, the cladding temperature, and the cooldown rate. After shattering of cladding, the oxide scale is simply removed. This shattering criterion deviates from the experiment of Chung and Kassner when the maximum cladding temperature exceeds 1560 K, and the model can’t reveal the impact of the cladding surface temperature before cooldown on cladding conditions after shattered. An oxidation model based on reaction-diffusion equations at the temperature range from 923K to 2098K is developed in this study. By comparison with experimental data, the model shows reasonable results. Based on the oxidation model, the advanced shattering criterion is adopted, and a new empirical model to describe the cladding conditions after shattered is proposed. In present shattering model, R(T, m), which is the ratio between the area of new crack surfaces in the metal layer and the area of outer cladding surface, is the function of T (the temperature of the cladding surface before cooldown) and m (the thickness of the metal layer). With the help of single-rod QUENCH experiment, the preliminary expression of R(T, m) is obtained, and the results are in a good agreement qualitatively with the observation in this experiment. Further activities should focus on the impact of m and T on R(T, m), which needs more detailed single-rod experiments. Those developed models can be implemented into the SCDAP/RELAP5 code easily and used in the severe accident analysis in the future.
Primary Investigation on the Mechanism of Gravity Separation of the Droplets in the Steam Flow Field
Authors: Zhang Jinyi , Bo Hanliang
Published: April 2011

A physical description of the formative cause and the ascension height of droplets is given according to the mechanism of gravity separation of the droplets in the steam flow field. In order to analyze the relationship between the height of gravity separation space and steam wetness, the dynamic single-drop model based on some simplified hypotheses is adopted, a comparison between the calculations and the experimental data is carried out. Based on this model and its analysis, the effects of the gravity separation space height, the velocity of the vapor flow, the droplet diameter as well as the initial velocity on the gravity separation efficiency are discussed in details. The qualitative description and analysis for the mechanism of gravity separation of the droplets in the steam flow field in this paper lays the groundwork for the qualitative analysis of the dynamic single-drop model.
TRACE5 Simulation of Condensation-Induced Water Hammer Phenomena
Authors: Gallardo S. , Abella V. , Verdu´ G.
Published: April 2011

The purpose of this work is to test the capability of TRACE5 code in the simulation of thermal-hydraulic transients concerning Condensation-Induced Water Hammer (CIWH) phenomena in a horizontal branch pipe connected to the vessel downcomer. The CIWH is produced by the condensation of the steam by subcooled water counterflow in the horizontal pipe, which causes two-phase flow interfacial instability, and is capable of initiating a severe water hammer, possibly leading to significant plant damage. The work is developed in the frame of OECD/NEA ROSA Project Test 2, performed in the Large Scale Test Facility (LSTF) of the Japan Atomic Energy Agency (JAEA) [1]. The purpose is to provide an analytical model for the LSTF installation, in order to evaluate the critical inlet water flow rates and system pressures of CIWH in a long horizontal pipe without using interfacial friction factor or heat transfer coefficients and using the default TRACE criterion of transition from stratified to a slug flow. The analytical model is designed with the thermal-hydraulic code TRACE5 via 1D-components, reproducing the actual branch where the CIWH is produced. A TEE component is connected to a FILL component, which simulates the water injection, and to a BREAK component set to the boundary conditions that simulate the downcomer. Our model uses one-dimensional flow equations and default correlations of interfacial shear stress and heat and mass transfer available by TRACE. Several comparisons are performed, varying pressure system and water injection mass flow rates. Simulated pressure pulses are characterized, studying parameters such as geometry nodalization, time-step effect, Courant number, numerical diffusion, etc. Results show that 1D model slightly underestimates the maximum pressure pulse intensity in all cases considered.
Clarification of Ejection and Sweep in Rectangular Channel Turbulent Flow
Authors: Biddinika Muhammad Kunta , Watanabe Noriyuki , Aritomi Masanori , Kikura Hiroshige
Published: April 2011

The experimental study has been carried out to investigate the behavior of ejection and sweep events in a rectangular channel turbulent flow. The channel is a 1800 mm long vertical channel with a cross sectional area of 100 mm and 20 mm. The events are studied by obtaining velocity components of the flow by using the ultrasonic measurement method (UVP). This paper clarifies the capability of the UVP for investigating the sweep and ejection events.
Application of RELSIM-RELAP/SCDAPSIM for University Training and Simulator Development
Authors: Allison Chris M. , Allison Brian S. , Luettringhaus Uwe , Hohorst Judith K.
Published: April 2011

RELAP/SCDAPSIM, designed to predict the behavior of reactor systems during normal and accident conditions, is being developed as part of the international SCDAP Development and Training Program (SDTP). RELSIM, an advanced interactive simulator Graphical User Interface, is a commercially available package being developed by Risk Management Associates (RMA). The combined package, RELSIM-RELAP/SCDAPSIM, is being used for training of university students and other novice reactor systems analysts to help them understand how complex thermal hydraulic and/or reactor systems perform under realistic and postulated conditions. RELAP/SCDAPSIM uses internationally developed and validated system thermal hydraulic, fuel behavior, and severe accident models in combination with a flexible building block approach to model thermal hydraulic and reactor systems. RELSIM also uses a building block approach and user defined graphics screens in combination with the ability to interactively control the RELAP/SCDAPSIM simulation. As a result, students and analysts can use the package to describe both simple and complex thermal hydraulic systems ranging from simple pipes and university-scale experimental facilities up through current and conceptual reactor systems. This paper gives a brief description of the RELSIM-RELAP/SCDAPSIM package and then provides a discussion of how the package is being used for student and analyst training, The discussion includes the development of training tutorials and videos for novice users, the development of representative sample problems and graphics displays, and the type of training provided to support the users. A case study is presented in the paper outlining the sample problems and displays for use in novice RELAP5 and RELAP/SCDAPSIM user training classes.
Snapshot Review of the Regulation of Gas Voids in Nuclear Steam Supply Systems in the United States
Authors: Ezekoye L. Ike , Turkowski William M.
Published: April 2011

The recent NRC Generic Letter (GL) 2008-01 titled “Managing Gas Intrusion in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems” to nuclear power plant licensees in the United States requires demonstration of suitable design, operational testing and control measures in order to maintain licensing commitments [1]. The generic letter outlines a number of actions that are detailed in nature; such as establishing pump void tolerance limits, limits on pump suction void fractions, etc. Each addressee was requested to evaluate their Emergency Core Cooling System (ECCS), Decay Heat Removal (DHR) system, and Containment Spray (CS) system. For each of these systems, design, operation, and test procedures were evaluated to assure that gas intrusion is minimized and monitored in order to maintain system operability and compliance with the requirements of 10 Code of Federal Regulation (CFR) 50 Appendix B [2]. In the GL 2008-01, licensees were requested to evaluate the ECCS, DHR and CS systems along four principal areas to ensure that gas accumulation is maintained less than the amount that challenges the operability of the systems, and that licensees shall take appropriate actions when the conditions are identified. The four principal areas are licensing basis, design, testing, and corrective actions. Each addressee was requested to provide a summary description of how the “REQUESTED ACTIONS” in the generic letter were addressed within nine months of the generic letter issue date. If an addressee determined that system or procedure modifications were necessary based on the review of the requested actions but cannot be accomplished within nine months of the date of the generic letter, then the addressee should provide a plan and schedule for completion of the actions. Many plants used their corrective action programs to accomplish this task. In its response, the licensee addressed any alternative course of action that it proposed to take, including the basis for the acceptability of the proposed alternative course of action. The nuclear industry, under the auspices of the Nuclear Energy Institute, has worked collaboratively with the industry to develop solutions and responses to the nine month NRC request, and these responses were submitted in October of 2008. Since that time, the NRC has been reviewing the plant submittals and issuing requests for additional information (RAIs) to the plants for clarification of their respective programs. This paper provides a snapshot review of the regulation of gas voids in the United States by focusing not only on industry actions to address the generic letter but also on the nature of the NRC requests to the nuclear plants for clarification of plant gas mitigation programs. The goal of the paper is to explore if the RAIs will provide some insights on NRC expectations of the industry as plants address gas intrusion in safety related Nuclear Steam Supply Systems (NSSS).
Experimental Investigation on the Performance of Naphthalene Heat Pipe in Half-Circumferential Heating Method
Authors: Liu Yun , Zhang Hong , Zhan Dongdong , Yin Caixia
Published: April 2011

Based on the characteristics of a carbon steel-naphthalene heat pipe, a new type of medium temperature heat pipe solar receiver has been developed. According to Direct Steam Generation (DSG) with solar parabolic trough concentrators, a simulation experiment is founded which used a new half-circumferential heating method. At the working dip angles 4° and 8°, the working temperature of heat pipe is stabilized at 250°C, 300°C, 350°C, 380°C, respectively. In this article, the temperature uniformity in circumferential direction, thermal resistance and heat transfer coefficient of the carbon steel-naphthalene has been analyzed and studied. The results indicate: the temperature uniformity in circumferential direction is below 20°C. The optimum filling ratio is 30% and when used this filling ratio, the total thermal resistance basically maintained below 0.23°C/W. Heat transfer coefficient increased with the increase of the transfer power. This article serves as a reference to understanding the heat transfer performance of the carbon steel-naphthalene heat pipe in medium soar receiver.
Bruce Power Aging Obsolescence Program
Authors: Cruchley Ian , Dam Rick , Gold Ralf , Ferguson Brian
Published: April 2011

The Aging and Obsolescence Program (AOP) developed by AECL in cooperation with Bruce Power ensures that Bruce Power is able to proactively manage plant critical component vulnerabilities before failure, thereby improving unit forced outage rates and reliability. AOP involves application of INPO AP-913 guidance for aging and obsolescence. The process includes component criticality identification and prioritization, single point vulnerability identification, and development of the technical basis to support maintenance. This includes replace or repair strategies, identification of critical spare parts and stocking parameters, through to the identification and resolution of obsolescence issues. The program is applicable to all components in a plant, but is being applied initially to critical components. This includes all Bruce B criticality category 1 components and those components that have caused plant trips or outages The program was also expanded to include review of buried piping for both Bruce A and B, additional plant systems based upon health status, and heat exchangers. Critical Spare Parts and Obsolescence Assessments identify and manage critical spare parts and obsolescence for Bruce Power SSCs (structures, systems, and components) and optimize spare parts inventory, which is intended to meet both planned and un-planned demand. In order to facilitate implementation of the AOP, the project includes integration of the program into Bruce Power processes and procedures. The cooperation between Bruce Power and AECL on AOP began as a small pilot project in 2007 where the program and procedures were developed by analysis of a few select components. The paper describes the Bruce Power Aging Obsolescence Program, the novelties and improvements of this integrated methodology and progress made to date.
Study of Interfacial Friction Force for Bubble Flows in a 2×1 Rods Channel Simplifying BWR
Authors: Kawahara Akimaro , Sadatomi Michio , Nakamoto Yutaro , Masuda Takatoshi
Published: April 2011

Most of recent subchannel analysis codes are based on a multi-fluid model, and accurate evaluation of the constitutive equations in the model is essential. In order to get an accurate one of the interfacial friction force in two-phase bubble flows, experimental data on drag coefficient and interfacial area concentration have been obtained for air-water flows in 2×1 rods channel simplifying a BWR fuel rod bundle. In order to know the effects of liquid properties on the data, temperature of the test water was changed from 18 to 50 °C. The data are compared with the existing correlations reported in literatures. As a result, Hibiki and Ishii (2001) semi-theoretical correlation is found to give the best prediction against the present interfacial area concentration data. Delhaye and Bricard (1994) correlation also gives reasonably good prediction if their correlation were modified by incorporating liquid property effects. As for the drag coefficient, no correlation exist which can predict well the present data. Therefore, we developed a new correlation including three dimensionless numbers, i.e., bubble Capillary number, Morton number and Eo¨tvo¨s number. The correlation could predict well Liu et al.’s data (2008) as well as the present data.
Condition Assessment of NPP Cables Through Indenter Modulus and Break-Elongation Test
Authors: Liu Tao , Han Fei , Shi Haining , Jin Xinming
Published: April 2011

Class IE electric cables can generally withstand 40 years of degradation from predicted operational environments and still perform safety-related functions even during and after accidents. These cables degrade through deterioration of insulation material, possibly leading to mechanical and electrical failure after decades of operation. The elongation at break is usually used as the critical parameter. However, elongation testing is destructive and requires relatively large specimens, making it undesirable for analyzing installed cables. In this paper, indenter modulus and break-elongation test for condition assessment of NPP cables were performed after accelerated ageing under heating and radiation. The test results showed that the relation between break-elongation and indenter modulus, and concluded that Indenter modulus can be effectively used to condition assessment of NPP cable ageing degradation.
Preliminary Level 1 PSA Results for SFR-600 Conceptual Design
Authors: Kim Tae-Woon , Han Sang-Hoon , Jeong Hae-Yong
Published: April 2011

A sodium-cooled fast reactor (SFR), SFR-600, is under development at KAERI. Its fuel is the metal fuel of U-TRU-Zr and it uses sodium as coolant. Its advantages are found in the aspects of an excellent uranium resource utilization, inherent safety features, and non-proliferation. SFR-600 has passive safety features such as passive shutdown functions, passive pump coast-down features, and passive decay heat removal systems. It has inherent reactivity feedback effects. The probabilistic safety assessment (PSA) will be one of the initiating subjects for designing it from the aspects of a risk informed design (RID) as well as a technology-neutral licensing (TNL). Accident scenarios which lead to the core damage should be identified for the development of a Level-1 PSA model. Preliminary level 1 PSA models and the results for the metal fuel SFR-600 conceptual design are introduced here.
Magnetic properties of ZnO:V films formed by pulsed laser deposition with bias voltage application
Authors: Asano Kei , Doi Shingo , Yamaguchi Hiroyuki , Komiyama Takao , Chonan Yasunori , Aoyama Takashi
Published: April 2011

Magnetic properties of ZnO films doped with V atoms (a 3d transition metal) were investigated by fabricating specimens using pulsed laser deposition (PLD) with bias voltage application. Electron concentrations of the ZnO:V films were changed by two methods: one was to dope with conventional n-type and p-type impurities, and the other was to change native (donor-type) defect concentrations by applying bias voltages during the film deposition. In M-H curves, smaller magnetization was observed for the film with a low electron concentration (5×1016 cm−3) and it increased linearly with the applied magnetic field, while larger magnetization was observed for the film with a medium electron concentration (5×1018 cm−3) and it exhibited a saturation at about 3 kOe. The saturation magnetization had maximum values for the electron concentrations of 1×1018–5×1018 cm−3 for the films formed by using either dopant impurities or PLD bias voltages. Anomalous Hall effect measurement of the films showed that the convergence of the Hall resistivity occurred at the same magnetic field as where the saturation of the magnetization occurred in the M-H curve.
One Step at a Time
Authors: Gough Nancy R.
Published: April 2011

Cortical neurons rely on atypical Rho proteins Rnd2 and Rnd3 to inhibit RhoA in different compartments to allow proper migration during embryonic development.
Recovering from Bladder Injury
Authors: Gough Nancy R.
Published: April 2011

Hedgehog signaling activates Wnt signaling to promote regeneration of the bladder urothelium after chemical injury or injury due to infection.
Mitochondrial Positioning in T Cells
Authors: Foley John F.
Published: April 2011

Recruitment of mitochondria by a fission factor to immune synapses in T cells modulates T cell receptor signal strength.
Hunting for Those with Heavy Hearts
Authors: Boxer Rebecca S.
Published: April 2011

Biomarkers may help to identify people with heart hypertrophy before the manifestation of heart failure.
K
+
Efflux Is Required for Histone H3 Dephosphorylation by Listeria monocytogenes Listeriolysin O and Other Pore-Forming Toxins
Authors: Hamon Mélanie Anne , Cossart Pascale
Published: April 2011

Chromatin modification triggered by bacteria is a newly described mechanism by which pathogens impact host transcription.
Listeria monocytogenes
dephosphorylates histone H3 through the action of listeriolysin O (LLO); however, the underlying mechanism is unknown. Here we show that an unrelated pore-forming toxin,
Aeromonas
aerolysin, also provokes H3 dephosphorylation (dePH3). As reported for aerolysin, we show that LLO and related toxins induce a pore-dependent K
+
efflux and that this efflux is the signal required for dePH3. In addition, LLO-induced K
+
efflux activates caspase-1. However, we demonstrate that dePH3 is unlinked to this activation. Therefore, our study unveils K
+
efflux as an important signal leading to two independent events critical for infection, inflammasome activation and histone modification.
Mild traumatic brain injury among a cohort of rugby union players: predictors of time to injury: Figure 1
Authors: Hollis Stephanie J , Stevenson Mark R , McIntosh Andrew S , Li Ling , Heritier Stephane , Shores E Arthur , Collins Michael W , Finch Caroline F
Published: April 2011

This study reports the time to sustain a mild traumatic brain injury (mTBI) among a cohort of community rugby union players. Demographic and player characteristics were collected and players followed up for between one and three playing seasons. 7% of the cohort sustained an mTBI within 10 h of game time, increasing twofold to 14% within 20 h. The mean time to first mTBI was 8 h with an SD of 6.2 (median 6.8 h; IQR: 2.9–11.7 h). Players reporting a recent history of concussion were 20% more likely to sustain an mTBI after 20 h of game time compared with those with no recent history of concussion. Players were likely to sustain an mTBI in shorter time if they trained for <3 h/week (HR=1.48, p=0.03) or had a body mass index <27 (HR=1.77, p=0.007). The findings highlight modifiable characteristics to reduce the likelihood of shortened time to mTBI.
Gender differences in occupational exposure patterns
Authors: Eng Amanda , 't Mannetje Andrea , McLean Dave , Ellison-Loschmann Lis , Cheng Soo , Pearce Neil
Published: April 2011

Objectives

The authors conducted a population-based survey to examine gender differences in occupational exposure patterns and to investigate whether any observed differences are due to: (a) gender differences in occupational distribution; and/or (b) gender differences in tasks within occupations.

Methods

Men and women aged 20–64 years were randomly selected from the Electoral Roll and invited to take part in a telephone interview, which collected information on self-reported occupational exposure to specific dusts and chemicals, physical exposures and organisational factors. The authors used logistic regression to calculate prevalence ORs and 95% CIs comparing the exposure prevalence of males (n=1431) and females (n=1572), adjusting for age. To investigate whether men and women in the same occupation were equally exposed, the authors also matched males to females on current occupation using the five-digit code (n=1208) and conducted conditional logistic regression adjusting for age.

Results

Overall, male workers were two to four times more likely to report exposure to dust and chemical substances, loud noise, irregular hours, night shifts and vibrating tools. Women were 30% more likely to report repetitive tasks and working at high speed, and more likely to report exposure to disinfectants, hair dyes and textile dust. When men were compared with women with the same occupation, gender differences were attenuated. However, males remained significantly more likely to report exposure to welding fumes, herbicides, wood dust, solvents, tools that vibrate, irregular hours and night-shift work. Women remained more likely to report repetitive tasks and working at high speed, and in addition were more likely to report awkward or tiring positions compared with men with the same occupation.

Conclusion

This population-based study showed substantial differences in occupational exposure patterns between men and women, even within the same occupation. Thus, the influence of gender should not be overlooked in occupational health research.
Women who smoke like men die like men who smoke: findings from two Australian cohort studies
Authors: Jamrozik Konrad , McLaughlin Deirdre , McCaul Kieran , Almeida Osvaldo P , Wong Kore Yiee , Vagenas Dimitrios , Dobson Annette
Published: April 2011

Background

There is controversy about whether men and women with similar smoking histories have similar incidence and mortality rates from smoking related diseases.

Objective

To compare mortality rates from all causes of death and various smoking related causes for men and women smokers categorised by numbers of cigarettes smoked and for ex-smokers by time since quitting.

Methods

This was a 10-year follow-up study with deaths identified from the National Death Index. The setting was two cohort studies in Australia established in 1996. Participants were: men (n=12 154) and women (n=11 707) aged (mean (SD)) 72.1 (4.4) and 72.5 (1.5) years, respectively, when recruited. The main outcome measure was HRs for men and women separately and RRs calculated from combined analyses using proportional hazards models (for deaths from all causes) and competing risks proportional hazards models (for specific causes).

Results

HRs for deaths from all causes for men (n=3549 deaths) and women (n=2665 deaths) among smokers increased with amount smoked and for ex-smokers decreased with time since quitting. Similar effects were found for various groups of smoking-related conditions with the dose-response effects largest for lung cancer and chronic obstructive pulmonary disease. The ratios of HRs for women relative to men were near unity and the 95% CIs included unity for almost all comparisons.

Conclusions

The data provide strong evidence that men and women with similar patterns of smoking experience similar rates of death due to smoking.
Distribution of residual load and true shaft resistance for a driven instrumented test pile
Authors: Kim Sung-Ryul , Chung Sung-Gyo , Fellenius Bengt H.
Published: April 2011

Foundation conditions are studied for a series of apartment buildings in a shore area reclaimed from the Nakdong River estuary delta west of Busan, South Korea, in full-scale field tests on two 600 mm, post-driving grouted, concrete cylinder piles instrumented with strain gages, driven through compressible layers and a short distance into underlying dense sand at depths of 56 m (Shinho) and 35 m (Myeongji). One test pile was provided with an O-cell so that after an initial O-cell test, a subsequent head-down test only affected pile shaft resistance. The purpose was to evaluate drivability of the piles, magnitude of the drag load due to consolidating soils, and potential settlement (downdrag) of the piled foundations. Early in the study, it became apparent that the internal process of heating and cooling of the grout during the hydration process and swelling from absorption of water affected the strain records and the assessment of residual load in the test piles during the wait time before the static loading test. The paper reports the measurements, analyses, and method for determining residual load, strain-dependent modulus of test piles, and actual load distribution in the test piles. The results are correlated to cone penetration test (CPTU) sounding data and effective stress analysis.
Role of fines on cohesive behavior of mine tailings inferred from critical shear stress
Authors: Geremew Africa M. , Yanful Ernest K.
Published: April 2011

The significance of fines on the cohesive behavior of mine tailings has been investigated by examining the incipient motion of the tailings. Sixteen laboratory experiments were performed in a Plexiglas laboratory annular column on re-constituted mine tailings under a 50 cm water cover. Re-suspension was produced by a Teflon stirrer and the velocity field in the column was characterized using a laser Doppler velocimeter (LDV). The pressure change in the boundary layer was also measured with a Preston tube. It was observed that the nondimensional critical shear stresses showed deviation from those of the noncohesive model results at a fines content greater than 50%–55%. An empirical relation that shows the relation between the boundary shear stress deviation and the percent fines in the tailings was proposed. Regression analysis of the experimental results showed that a power law relationship could reasonably be used to describe the relation between the measured nondimensional excess bed shear stress and the erosion rate. It is proposed that the value of β (the erosion rate constant) could be taken as 1 for mine tailings that show cohesive behavior.
Influence of particle size on the correlation between shear wave velocity and cone tip resistance
Authors: Karray Mourad , Lefebvre Guy , Ethier Yannic , Bigras Annick
Published: April 2011

The construction of the Péribonka dam involved deep compaction of its foundation using vibroflotation and dynamic compaction. Surface wave testing was used, in addition to classical tests (cone penetration tests (CPTs) and standard penetration tests (SPTs)) for the assessment of vibrocompaction. More than 900 shear wave velocity (Vs) and 1000 CPT profiles were obtained. This set of tests performed prior to and following vibrocompaction constitutes an important data bank, used in this study to establish a relationship between normalized shear wave velocity, Vs1, normalized tip resistance, qc1, and mean grain size, D50. Using the Péribonka project data obtained on fairly coarse sands in conjunction with the Canadian Liquefaction Experiment (CANLEX) project data obtained on fine sands has confirmed the significant effect of particle-size distribution on the relationship between Vsand qc. The paper proposes a correlation between Vs1, qc1, and D50for uncemented and Holocene-age granular soils in continuity with the relation developed by Wride et al. from the CANLEX project.
Thermal radiation and conduction properties of materials ranging from sand to rock-fill
Authors: Fillion Marie-Hélène , Côté Jean , Konrad Jean-Marie
Published: April 2011

This paper presents an experimental study on thermal radiation and the thermal conductivity of rock-fill materials using a 1 m × 1 m × 1 m heat transfer cell. Testing temperatures are applied by temperature-controlled fluid circulation at the top and bottom of the sample. Heat flux and temperature profiles are measured to establish the effective thermal conductivity λe, which includes contributions from both conduction and radiation heat transfer mechanisms. The materials studied had an equivalent particle size (d10) ranging from 90 to 100 mm and porosity (n) ranging from 0.37 to 0.41. The experimental results showed that thermal radiation greatly affects the effective thermal conductivity of materials with λe values ranging from 0.71 to 1.02 W·m−1·K−1, compared with a typical value of 0.36 W·m−1·K−1 for conduction alone. As expected, the effective thermal conductivity increased with particle size. An effective thermal conductivity model has been proposed, and predictions have been successfully compared with the experimental results. Radiation heat transfer becomes significant for d10 higher than 10 mm and predominant at values higher than 90 mm. The results of the study also suggest that the cooling potential of convection embankments used to preserve permafrost conditions may not be as efficient as expected because of ignored radiation effects.
GENERALIZED STATISTICS FIELDS AND THE TWO-DIMENSIONAL DERIVATIVE-COUPLING MODEL REVISITED
Authors: BELVEDERE L. V. , RODRIGUES A. F.
Published: April 2011

We reexamine the two-dimensional derivative-coupling model within the operator approach that takes into account the quantum corrections of the fully bosonized Hamiltonian. As a consequence of the fact that there is no true spin-statistics theorem in two dimensions, the operator solution is rewritten in terms of a generalized Mandelstam soliton operator with continuous Lorentz spin (generalized statistics). The particular case corresponding to the Schroer model is considered: the effect of the vector-current-derivative coupling is to give a noncanonical scale dimension for the underlying free Fermi field promoting it to a free Mandelstam operator with generalized statistics.
THE GLOBAL SYNCHRONIZATION OF A NEW HYPERCHAOTIC LORENZ SYSTEM
Authors: WANG TIANSHU , WANG XINGYUAN
Published: April 2011

This paper studies the global synchronization of a new hyperchaotic Lorenz system proposed by Wang et al. Based on the Lyapunov stability theory, the coupled control matrix is discussed when either knowing or unknowing the system boundary, respectively. The analysis of theory and numerical simulations show that the synchronization of hyperchaos Lorenz system can be realized effectively with the methods.
INTERACTION OF A THREE-LEVEL ATOM WITH A SINGLE-MODE FIELD IN A TWO PHOTON RESONANT CAVITY
Authors: NATH DEBRAJ , DAS P. K.
Published: April 2011

In this paper we discuss an extension of Jaynes–Cummings model by adding a further atomic level to support a second resonance and cooperative effects in multi-atom systems. A successive passage of a three-level atom in the V configuration interacting with one quantized mode of electromagnetic field in a cavity will be considered to study atomic inversion and entropy evolution of the state.
ON THE DEGREE DISTRIBUTION OF A BIPARTITE NETWORK WITH REWIRING DYNAMICS
Authors: FAN H. , WANG Z.
Published: April 2011

Bipartite network with rewiring dynamics exists in many real-world networks. Various models based on the mean-field approximation are successfully proposed for the degree distribution of rewiring dynamics in the bipartite network. However, there are implicit or even obvious differences among these models, despite that they are utilized for modeling the same rewiring problem. How the differences among these models arise and how the differences influence the solution of the degree distribution remain unresolved. Firstly, the models for a bipartite network with rewiring dynamics are categorized into three versions, which are named as a two steps version model (TSV model), a one step version-I model (OSV-I model), and a one step version-II model (OSV-II model) in the present paper. The differences among the three versions models are clarified. Then, we derive an exact solution for the TSV model and that for the OSV-II model. Furthermore, we prove that the exact solution for the steady degree distribution of the TSV model and that of the OSV-II model are globally asymptotically stable. Based on the exact solutions, the differences of the solution of the degree distribution among the three versions models are analyzed.
A NEW ELECTRONICALLY-TUNABLE ACTIVE-ONLY UNIVERSAL BIQUAD
Authors: SINGH A. K. , SENANI R. , BHASKAR D. R. , SHARMA R. K.
Published: April 2011

A number of configurations for realizing voltage-mode (VM) biquads using op-amps and OTAs have been presented in the literature, however, none of these provide the following desirable properties simultaneously: (i) realizability of all the five standard filters (namely; low pass, high pass, band pass, band stop and all pass), (ii) tunability of all the three filter parameters (namely; ω0, bandwidth or Q0and gain) and (iii) not requiring any realization condition in any of the five filter responses. This paper presents a new configuration which does possess all the above mentioned desirable properties simultaneously while using only two internally-compensated type op-amps and a reasonable number of OTAs. The workability of the new configuration has been demonstrated by SPICE simulations based upon CMOS Op-amp and CMOS OTAs.
A NEW ROBUST AND HIGH-PERFORMANCE HYBRID FULL ADDER CELL
Authors: MIRZAEE REZA FAGHIH , MOAIYERI MOHAMMAD HOSSEIN , KHORSAND HAMID , NAVI KEIVAN
Published: April 2011

A new 1-bit hybrid Full Adder cell is presented in this paper with the aim of reaching a robust and high-performance adder structure. While most of recent Full Adders are proposed with the purpose of using fewer transistors, they suffer from some disadvantages such as output or internal non-full-swing nodes and poor driving capability. Considering these drawbacks, they might not be a good choice to operate in a practical environment. Lowering the number of transistors can inherently lead to smaller occupied area, higher speed and lower power consumption. However, other parameters, such as robustness to PVT variations and rail-to-rail operation, should also be considered. While the robustness is taken into account, HSPICE simulation demonstrates a great improvement in terms of speed and power-delay product (PDP).
A SEAMLESS-CONTROLLED DIGITAL PLL USING DUAL LOOPS FOR HIGH SPEED SOCS
Authors: SHIN YOUNG SAN , WEE JAE-KYUNG , HA JONG-CHAN , LIM JI-HOON , KIM YONG-JU , SON YOUNG-SANG
Published: April 2011

A new dual-loop digital phased-locked loop (DPLL) architecture is presented. This novel architecture is designed to provide a wide operating frequency range, high precision, and small jitter, and fits over a relatively small area. To achieve these characteristics, the architecture is implemented using a coarse loop with an UP/DOWN counter and a coarse digital-to-analog converter (DAC) to rapidly reduce the phase error, and a fine loop with a time-to-digital converter (TDC) and a fine DAC to provide more precision. Furthermore, the seamless-frequency tracking architecture based on a code conversion between the coarse cell and the fine cell of the DAC is devised to improve the lock-in stability. The chip is fabricated with Dongbu HiTek 0.18-μm CMOS technology. It has a wide operation range of 0.4–1.4 GHz, and an area of 0.195 mm2. The measured results show 15.64 ps peak-to-peak jitter and 2.22 ps rms jitter, and a power dissipation of 16.2 mW at 1 GHz.
DYNAMICS IN TIME-DELAY RECURRENTLY COUPLED OSCILLATORS
Authors: JIANG CAN , GUO SHANGJIANG , HE YIGANG
Published: April 2011

A model of time-delay recurrently coupled spatially segregated neural oscillators is proposed. Each of the oscillators describes the dynamics of average activities of excitatory and inhibitory populations of neurons. Bifurcation analysis shows the richness of the dynamical behaviors in a biophysically plausible parameter region. We find oscillatory multi-stability, hysteresis, and stability switches of the rest state provoked by the time delay as well as the strength of the connections between the oscillators. Then we derive the equation describing the flow on the center manifold that enables us to determine the bifurcation direction and stability of bifurcated periodic solutions and equilibria. We also give some numerical simulations to support our main results.
DESIGN-ORIENTED BIFURCATION ANALYSIS OF POWER ELECTRONICS SYSTEMS
Authors: TSE CHI K. , LI MING
Published: April 2011

Bifurcation analysis has been applied to many power electronics circuits. Literature abounds with results regarding the various ways in which such circuits lose stability under variation of some selected parameters, e.g. via period-doubling bifurcation, Hopf bifurcation, border collision, etc. The current status of research in the identification of bifurcation behavior in power electronics has reached a stage where the salient types of bifurcation behavior, their underlying causes and the theoretical parameters affecting them have been well understood. Currently, the emphasis of research in this field has gradually shifted toward applications that are of direct relevance to practical design of power electronics. One direction is to apply some of the available research results in bifurcation behavior to the design of practical power electronics circuits. The main difficulty is that the abstract mathematical presentations of the available results are not directly applicable to practical design problems. In this paper we will discuss how research efforts may be directed to bridge this gap.
RECONSTRUCTING CONVEX POLYGONS AND CONVEX POLYHEDRA FROM EDGE AND FACE COUNTS IN ORTHOGONAL PROJECTIONS
Authors: BIEDL THERESE , HASAN MASUD , LÓPEZ-ORTIZ ALEJANDRO
Published: April 2011

We study the problem of reconstructing convex polygons and convex polyhedra given the number of visible edges and visible faces in some orthogonal projections. In 2D, we find necessary and sufficient conditions for the existence of a feasible polygon of size N and give an algorithm to construct one, if it exists. When N is not known, we give an algorithm to find the maximum and minimum sizes of a feasible polygon. In 3D, when the directions are covered by a single plane we show that a feasible polyhedron can be constructed from a feasible polygon. We also give an algorithm to construct a feasible polyhedron when the directions are covered by two planes. Finally, we show that the problem becomes NP-hard when the directions are covered by three or more planes.
GUARDING ORTHOGONAL ART GALLERIES WITH SLIDING CAMERAS
Authors: KATZ MATTHEW J. , MORGENSTERN GILA
Published: April 2011

We study the problem of guarding an orthogonal art gallery with security cameras sliding back and forth along straight tracks. We show that if only vertical (alternatively, horizontal) tracks are allowed, then a solution minimizing the number of tracks can be found in polynomial time, and if both orientations are allowed, then a 2-approximation can be found in polynomial time for x-monotone galleries.
FIRST NON-VANISHING SELF-LINKING OF KNOTS (I) COMBINATORIC AND DIAGRAMMATIC STUDY
Authors: HSIEH CHUN-CHUNG
Published: April 2011

In this paper, following the scheme of [Borromean rings and linkings, J. Geom. Phys.60 (2010) 823–831; Combinatoric and diagrammatic study in knot theory, J. Knot Theory Ramifications16 (2007) 1235–1253; Massey–Milnor linking = Chern–Simons–Witten graphs, J. Knot Theory Ramifications17 (2008) 877–903], we study the first non-vanishing self-linkings of knots, aiming at the study of combinatorial formulae and diagrammatic representation. The upshot of perturbative quantum field theory is to compute the Feynman diagrams explicitly, though it is impossible in general. Along this line in this paper we could not only compute some Feynman diagrams, but also give the explicit and combinatorial formulae.
A MODEL OF THE TRANSMISSION DYNAMICS OF LEISHMANIASIS
Authors: AGYINGI EPHRAIM O. , ROSS DAVID S. , BATHENA KARTHIK
Published: April 2011

In this paper we present a susceptible–infectious–susceptible (SIS) model that describes the transmission dynamics of cutaneous Leishmaniasis. The model treats a vector population and several populations of different mammals. Members of the human population serve as the incidental hosts, and members of the various animals populations serve as reservoir hosts. We establish the basic reproduction number and the equilibrium conditions of the system. We use a generalization of the Lyapunov function approach to show that when the basic reproduction number is less than or equal to one, the diseases-free equilibrium is a global attractor, and that when it is greater than one the endemic equilibrium is a global attractor. We present numerical simulations that demonstrate the dynamics of the model for a system containing a human population and a single animal population.
STOCHASTIC SIMULATION OF A DIMER SODIUM PUMP
Authors: TEWARI SHIVENDRA G.
Published: April 2011

Sodium pump is known to play an important role in almost all organs of our human body like heart, kidney, liver, brain, etc. A number of mechanisms for sodium pumping have been proposed till date, with Albers–Post Model being most widely used. Recently, Clarke proposed a two-gear dimer sodium pump model to replace the classical Albers–Post Model. This dimer model has two gears of sodium pumping depending upon the available adenosine triphosphate (ATP) concentrations. The mathematical model governing the two gears of sodium pumping overestimated the total fluorescence change of sodium pump labeled with voltage-sensitve probe RH421, which responds to electrogenic reactions of the pump, for ATP concentrations lesser than 25 μM. In this article, a modification has been proposed to the existing dimer mathematical model. Also, it is well known that stochastic chemical kinetics of enzymes has a stronger physical basis than classical reaction rate equations. Hence, the modified mathematical model is simulated using STochastic Engine for Pathway Simulation (STEPS). The stochastic results are used to perform comparative analysis with experimental and deterministic results to validate the modified model and consequently the dimeric nature of sodium pump. The modified model gave a better prediction of total fluorescence change for over all possible range of ATP concentrations. Similar approach can be used to stochastically simulate other ion pumping processes.