bluuebunny/crossref_metadata_2025 huggingface dataset:
Dialog Antara Agama Menurut Perspektif Islam (An Islamic Perspective on Interfaith Dialogue)
Authors: Ramli Ahmad Faizuddin , Awang Jaffary
Published: October 2016

The existence of a pluralistic society, particularly in terms of race, religion and culture requires a platform in the community. In this case, interreligious dialogue is seen as an effective platform to build mutual understanding and tolerance among society. However, the practice of dialogue in society ironically based on a wrong understanding of interreligious dialogue, which is part of the religious pluralism method from West, and some regard it as a debate. Consequently, the phenomenon raises negative perceptions and understanding among the public about the true concept of interfaith dialogue. Therefore, this article discusses the concept of interreligious dialogue in the Islamic arena. The research design is qualitative using library research. The results show that Islam outlines three concepts of interreligious dialogue, the debate; da‘wah and building mutual understanding and good relations between religions. Here in particular the importance of interfaith dialogue among the players to understand the concept of interreligious dialogue to ensure the implementation of the dialogue takes place within the actual concept.
Characteristics of the Wake Behind a Transversely Oscillating Cylinder Near a Wall
Authors: Peter S. , De A. K.
Published: October 2016

In the present study, numerical investigation is carried out for flow past a transversely oscillating circular cylinder near a wall. A second-order finite-volume method employing diffuse interface immersed boundary method is used to handle the nonconforming boundaries. The cylinder is allowed to oscillate on a fixed Eulerian mesh in order to handle the moving boundary. Simulations are carried out for a number of forcing frequencies at three different gap distances and two amplitudes of oscillation with Reynolds number fixed at 200. While a pair of vortices is found to be shed near the stationary shedding frequency at larger gap distance, multiple interconnected vortices are observed at larger forcing frequencies. Proximity of the wall promotes greater interaction of the wall layer with the near wake resulting in inhibited irregular shedding. Energy transfer changes its direction when the correlation between the cylinder motion and the lift force is strongest. Positive energy transfer attains a peak at the onset of the synchronization regime accompanied by a weaker correlation. Amplitude of oscillation of the cylinder evidently has systematic effect on the drag coefficient and wake fluctuations, though lift force remains grossly unaltered. Lower amplitude of motion favors induced motion as opposed to larger ones where greater negative energy transfer occurs.
Probing and Imaging of Vapor–Water Mixture Properties Inside Partial/Cloud Cavitating Flows
Authors: Wan Churui , Wang Benlong , Wang Qian , Fang Yongliu , Liu Hua , Zhang Guoping , Xu Lianghao , Peng Xiaoxing
Published: October 2016

Experimental results of the void fraction, statistical chord length distribution (CLD), and bubble size distribution (BSD) inside and downstream of hydrodynamic cavities are presented at the laboratory scale. Various cavitating flows have been intensively studied in water tunnels for several decades, but no corresponding quantitative CLD and BSD data were reported. This experimental study is aimed at elaboration of a general approach to measure CLD in typical cavitating flows. Dual-tip electrical impedance probe (dtEIP) is used to measure the void fraction and CLD in different cavitation flows over a flat plate, including both supercavitation and sheet/cloud cavitation. For supercavitating flows, the void fraction of vapor is unity in the major cavity region. In contrast, the maximum void fraction inside the sheet/cloud cavitation region is less than unity in the present studies. The high vapor concentration region is located in the center of the cavity region. Based on the experimental data of CLD, it is found that the mean chord lengths are around 2.9–4.8 mm and 1.9–4.4 mm in the center region and closure region, respectively. The backward converting bubble diameters at the peak of BSD have similar magnitude, with probability density values exceeding 0.2. Empirical parameters of CLD and BSD are obtained for different cavity regions.
Entrance and Temperature-Dependent Property Effects on Laminar Duct Flows of Liquids
Authors: Del Giudice Stefano , Savino Stefano , Nonino Carlo
Published: October 2016

The results of a numerical investigation on the effects of the temperature dependence of viscosity and thermal conductivity in simultaneously developing laminar flows of liquids in straight ducts of constant cross sections are used to obtain new correlations for the axial distributions of the peripherally averaged local Nusselt number. Three different cross-sectional geometries are considered, corresponding to both axisymmetric (circular and concentric annular) and three-dimensional (square) ducts. Uniform heat flux boundary conditions are specified at the heated walls. Viscosity is assumed to vary with temperature according to an exponential relation, while a linear dependence of thermal conductivity on temperature is assumed. The other fluid properties are held constant. A superposition method is applied to obtain the values of the peripherally averaged local Nusselt number by separately considering the effects of temperature-dependent viscosity and those of temperature-dependent thermal conductivity.
Evolution of Hardware Morphology of Large-Scale Computers and the Trend of Space Allocation for Thermal Management
Authors: Nakayama Wataru
Published: October 2016

Thermal management of very large-scale computers will have to leave the traditional well-beaten path. Up to the present time, the primary concern has been with rising heat flux on the integrated circuit chip, while a space has been available for the implementation of high-performance cooling design. In future systems, the spatial constraint will become a primary determinant of thermal management methodology. To corroborate this perspective, the evolution of computer's hardware morphology is simulated. Simulation tool is the geometric model, where the model structure is composed of circuit cells and platforms for circuit blocks. The cell is the minimum circuit element whose size is pegged to the technology node, while the total number of cells represents the system size. The platforms are the models of microprocessor chips, multichip modules (MCMs), and printed wiring boards (PWBs). The major points of discussion are as follows: (1) The system morphology is dictated by the competition between the progress of technology node and the demand for increase in the system size. (2) Only where the miniaturization of cells is achieved so as to deploy a system on a few PWBs, ample space is created for thermal management. (3) In the future, the cell miniaturization will hit the physical limit, while the demand for larger systems will be unabated. Liquid cooling, where the coolant is driven through very long microchannels, may provide a viable thermal solution.
Superheater and Drum Lifetime Estimation: An Approach Based on Dynamic Analysis
Authors: Benato Alberto , Stoppato Anna , Mirandola Alberto , Destro Nicola , Bracco Stefano
Published: October 2016

The increasing penetration of variable and unpredictable renewable energy sources into the liberalized electricity market brings about significant changes in the management strategies of fossil fuel power plants. These new operation modes cause remarkable effects on the lifetime of the plants. Consequently, the operators of the plants need to be assisted by effective procedures, which are able to define suitable production plans. In the present paper, the authors propose a dynamic model which can be used to estimate the effects of the variations of thermodynamic and mechanical parameters during transient operation, start-ups and shut-downs. To check the effectiveness of the model, a combined cycle plant with a three-pressure level heat recovery steam generator has been selected. The geometry of the components, the influence of the environmental conditions, and the control strategies are included in the model. In this way, the residual lifetime of the most critical components can be predicted.
Modeling of Filter Cake Composition in Maximum Reservoir Contact and Extended Reach Horizontal Wells in Sandstone Reservoirs
Authors: Mahmoud Mohamed , Bageri Badr S. , Elkatatny Salaheldin , Al-Mutairi Saleh H.
Published: October 2016

Drilling mud should be properly designed to build an effective filter cake on the formation face during the drilling process. This filter cake should be removable to allow the oil and gas production. The need for removal increases when the liftoff pressure is high or when the formation drawdown is extremely low. An effective filter cake removal design includes the knowledge of the filter cake composition along the horizontal section. This paper, for the first time, introduces material balance model to predict the composition of the filter cake along the length of the lateral of an actual horizontal well drilled in a sandstone formation. The model is based on the material balance of two sources of solids: the first one is the drilling fluid solids and the second one is the drilled-formation solids. The mud used to drill the rock was contaminated by the drilled-formation solids. The parameters used to construct the model were composition of the mud and formation, efficiency of each separation stage, rate of penetration (ROP), and mud circulation rate. The model was validated with actual mud samples collected from different locations along the horizontal section of a sandstone formation. The model showed that the sand content in the filter cake is affected by ROP, rock composition, mud composition and volume, and efficiency of sand separation equipment. We came up with several correlations that can be used to design the drilling fluid operations in horizontal well to avoid the formation of irremovable filter cake.
Real-Size Experiments on Reverse Natural Air Convection Between Inclined Parallel Plates for New Insulation Methods in Solar Flat-Plate Collectors
Authors: Beikircher Th. , Berger V. , Möckl M.
Published: October 2016

Reverse natural air convection (hot plate top) was experimentally investigated between two inclined parallel aluminum plates (1 m × 2 m × 3 mm) with a separation distance of 20 mm to 100 mm. The inclination ϑ to the horizontal was varied from 0 deg to 90 deg. The mean temperatures of the plates have been adjusted to 90 °C and 30 °C resulting in Rayleigh numbers Ra between 2.7 × 104 and 3.3 × 106. The experimental conditions correspond to the back side of an absorber in a typical solar flat-plate collector, where the conventional insulation has been removed. The upper hot plate simulates the absorber and was electrically heated by an area heater, while the temperature distribution over the plate was measured. The lower cold plate was held isothermally by integrated water tubes and a thermostat. The side walls of the rectangular cavity were thermally connected to the colder plate and had a distance of 10 mm to the hot plate, comparable to a typical collector casing. The experimentally obtained results for Nu (Ra,ϑ) were mathematically described and compared to rare reverse convection data of other authors, gained at smaller aspect ratios/flow lengths and for adiabatic side walls: The formula of Elsherbiny approximately (within 10%) describes solar flat-plate collectors between 0 deg and 60 deg inclination, while the relations of Arnold, Ozoe, and Inaba show large errors up to 50%. Additionally, we experimentally showed that pure air gap insulation (30–50 mm) has surprisingly acceptable loss coefficients between 1.3 and 2.5 W/m2K depending on collector slope. It can be used as a cheap insulation method for low temperature collector applications. Additionally, inserting an 25–50 μm thick aluminum film symmetrically between the plates, a new and efficient insulation method for the absorber of a solar flat-plate collector was experimentally investigated: At plate distances of 30–50 mm, temperatures below 100 °C and slopes below 45 deg, this compact and cheap film insulation was proven to be equivalent to dry mineral wool and avoids its disadvantage of worsening insulation properties due to humidity.
Investigation on the Optimized Binary and Ternary Gallium Alloy as Thermal Interface Materials
Authors: Gao Yunxia , Wang Xianping , Liu Jing , Fang Qianfeng
Published: October 2016

This work presents an experimental study to enhance the thermal contact conductance of high performance thermal interface materials (TIMs) using gallium alloy. In this experiment, the gallium alloy-based TIMs are synthesized by a micro-oxidation reaction method, which consists of gallium oxides (Ga2O3) dispersed uniformly in gallium alloys. An experimental apparatus is designed to measure the thermal resistance across the gallium alloy-based TIMs under steady-state conditions. The existence of Ga2O3 can effectively improve the wettability of gallium alloys with other materials. For example, they have a better wettability with copper and anodic coloring 6063 aluminum-alloy without any extrusion between the interface layers. Gallium binary alloy-based TIMs (GBTIM) or ternary alloy based-TIMs (GTTIM) are found to increase the operational temperature range comparing with that of the conventional thermal greases. The measured highest thermal conductivity is as high as 19.2 Wm−1K−1 for GBTIM at room temperature. The wide operational temperature, better wettability, and higher thermal conductivity make gallium alloy-based TIMs promising for a wider application as TIMs in electronic packaging areas. The measured resistance is found to be as low as 2.2 mm2 KW−1 for GBTIM with a pressure of 0.05 MPa, which is much lower than that of the best commercialized thermal greases. In view of controlling pollution and raw materials wasting, the gallium alloy-based TIMs can be cleaned by 30% NaOH solution, and the pure gallium alloys are recycled, which can satisfy industrial production requirements effectively.
Mechanism of the S-Shaped Characteristics and the Runaway Instability of Pump-Turbines
Authors: Xia Linsheng , Cheng Yongguang , You Jianfeng , Zhang Xiaoxi , Yang Jiandong , Qian Zhongdong
Published: October 2016

Understanding the formation mechanism of the S-shaped characteristics (SSCs) and the relationship between flow structures and the runaway instability (RI) is the prerequisite for optimizing runner design to promote operational reliability and flexibility. In this study, a new turbine equation is derived to reveal the prime cause of the SSCs, and the influence of geometric parameters on the SSCs is analyzed. Moreover, the flow patterns in three model turbines of different specific-speeds are simulated by unsteady Computational fluid dynamics (CFD), and the correlation between inverse flow vortex structures (IFVSs) and the RI in the SSCs region is identified. Theoretical analysis shows that the turbine equation can theoretically predict the change trend of the first quadrant SSCs curves of the pump-turbines; the flow losses caused by small blade inlet angle, instead of the diameter ratio, are the primary cause of the SSCs. The numerical simulation results reveal that the IFVSs at the hub side of the runner inlet are the origin of the RI; when operating points are far away from the best efficiency point (BEP), the IFVS locations change regularly. For large guide vane openings (GVOs), the IFVSs first incept at the shroud side, and then translate to the hub side, and further back to the midspan, when the discharge decreases. The inception points (IPs) of the SSCs correspond to the onset of the IFVSs at the hub side, which are in advance of the zero-torque operating points (ZTOPs); therefore, the ZTOPs are located in the positive slope region, leading to RI. For small GVOs, however, the IFVSs only locate at the midspan; the IPs of the SSCs, having no definite correlation with the IFVSs, are coincided with or are below the ZTOPs, because the ZTOPs are in the negative slope region and RI disappears. It is also found that the IPs of SSCs are the turning points of the predominant states between the turbine effect and pump effect. These results are valuable for design and optimization of pump-turbine runners.
Numerical Investigations of Pressure Distribution Inside a Ventilated Supercavity
Authors: Cao Lei , Karn Ashish , Arndt Roger E. A. , Wang Zhengwei , Hong Jiarong
Published: October 2016

A numerical study has been conducted on the internal pressure distribution of a ventilated supercavity generated from a backward facing cavitator under different air entrainment coefficients, Froude numbers, and blockage ratios. An Eulerian multiphase model with a free surface model is employed and validated by the experiments conducted at St. Anthony Falls Laboratory of the University of Minnesota. The results show that the internal pressure in the major portion of the supercavity is primarily governed by the hydrostatic pressure of water, while a steep adverse pressure gradient occurs at the closure region. Increasing the air entrainment coefficient does not largely change the pressure distribution, while the cavity tail extends longer and consequently the pressure gradient near the closure decreases. At smaller Froude number, there is a more pronounced gravitational effect on the supercavity with increasing uplift of the lower surface of the cavity and a decreasing uniformity of the pressure distribution in the supercavity. With the increase of blockage ratio, the overall pressure within the supercavity decreases as well as the pressure gradient in the main portion of the supercavity. The current study shows that the assumption of uniform pressure distribution in ventilated supercavities is not always valid, especially at low Fr. However, an alternative definition of cavitation number in such cases remains to be defined and experimentally ascertained in future investigations.
Three-Dimensional Dynamic Modeling and Control of Off-Centered Bridge Crane Lifts
Authors: Garcia Anthony , Singhose William , Ferri Aldo
Published: October 2016

When cranes lift payloads off the ground, the payload may slide sideways or swing unexpectedly. This motion occurs when the payload is not directly beneath the overhead suspension point of the hoist cable. Given that cable suspension points can be hundreds of feet above the payload, it is difficult for crane operators to know if the hoist cable is vertical before lifting the payload off the ground. If an off-center lift creates substantial horizontal motion, then it can create significant hazards for the operators, the payload, and the surrounding environment. This paper develops a three-dimensional dynamic model that predicts motions of off-centered lifts.
The Escape of High Explosive Products: An Exact-Solution Problem for Verification of Hydrodynamics Codes
Authors: Doebling Scott W.
Published: October 2016

This paper documents the escape of high explosive (HE) products problem and demonstrates the use of the problem for code verification assessment. The problem, first presented by Fickett and Rivard (1974, “Test Problems for Hydrocodes,” LASL Report, Los Alamos Scientific Laboratory, Los Alamos, NM, Report No. LA-5479), tests the implementation and numerical behavior of a high explosive detonation and energy release model and its interaction with an associated compressible hydrodynamics simulation code. The problem simulates the detonation of a finite-length, one-dimensional piece of HE that is driven by a piston from one end and adjacent to a void at the other end. The HE equation of state is modeled as a polytropic ideal gas. The HE detonation is assumed to be instantaneous with an infinitesimal reaction zone. Via judicious selection of the material specific heat ratio, the problem has an exact solution with linear characteristics, enabling a straightforward calculation of the physical variables as a function of time and space. Implementation of the exact solution in the Python code ExactPack is discussed, as are verification cases for the exact solution code. The problem is used to conduct code verification assessment on a Lagrangian hydrodynamics code.
Micro/Nanocontact Between a Rigid Ellipsoid and an Elastic Substrate With Surface Tension
Authors: Yuan W. K. , Long J. M. , Ding Y. , Wang G. F.
Published: October 2016

For micro/nanosized contact problems, the influence of surface tension becomes prominent. Based on the solution of a point force acting on an elastic half space with surface tension, we formulate the contact between a rigid ellipsoid and an elastic substrate. The corresponding singular integral equation is solved numerically by using the Gauss–Chebyshev quadrature formula. When the size of contact region is comparable with the elastocapillary length, surface tension significantly alters the distribution of contact pressure and decreases the contact area and indent depth, compared to the classical Hertzian prediction. We generalize the explicit expression of the equivalent contact radius, the indent depth, and the eccentricity of contact ellipse with respect to the external load, which provides the fundament for analyzing nanoindentation tests and contact of rough surfaces.
Linking Internal Dissipation Mechanisms to the Effective Complex Viscoelastic Moduli of Ferroelectrics
Authors: Wojnar Charles S. , Kochmann Dennis M.
Published: October 2016

Microstructural mechanisms such as domain switching in ferroelectric ceramics dissipate energy, the nature, and extent of which are of significant interest for two reasons. First, dissipative internal processes lead to hysteretic behavior at the macroscale (e.g., the hysteresis of polarization versus electric field in ferroelectrics). Second, mechanisms of internal friction determine the viscoelastic behavior of the material under small-amplitude vibrations. Although experimental techniques and constitutive models exist for both phenomena, there is a strong disconnect and, in particular, no advantageous strategy to link both for improved physics-based kinetic models for multifunctional rheological materials. Here, we present a theoretical approach that relates inelastic constitutive models to frequency-dependent viscoelastic parameters by linearizing the kinetic relations for the internal variables. This enables us to gain qualitative and quantitative experimental validation of the kinetics of internal processes for both quasistatic microstructure evolution and high-frequency damping. We first present the simple example of the generalized Maxwell model and then proceed to the case of ferroelectric ceramics for which we predict the viscoelastic response during domain switching and compare to experimental data. This strategy identifies the relations between microstructural kinetics and viscoelastic properties. The approach is general in that it can be applied to other rheological materials with microstructure evolution.
Laser Autogenous Brazing of Biocompatible, Dissimilar Metals in Tubular Geometries
Authors: Satoh Gen , Brandal Grant , Naveed Syed , Lawrence Yao Y.
Published: October 2016

The successful joining of dissimilar metal tubes would enable the selective use of the unique properties exhibited by biocompatible materials such as stainless steel and shape memory materials, such as NiTi, to locally tailor the properties of implantable medical devices. The lack of robust joining processes for the dissimilar metal pairs found within these devices, however, is an obstacle to their development and manufacture. Traditional joining methods suffer from weak joints due to the formation of brittle intermetallics or use filler materials that are unsuitable for use within the human body. This study investigates a new process, Laser Autogenous Brazing, that utilizes a thermal accumulation mechanism to form joints between dissimilar metals without filler materials. This process has been shown to produce robust joints between wire specimens but requires additional considerations when applied to tubular parts. The strength, composition, and microstructure of the resultant joints between NiTi and stainless steel are investigated and the effects of laser parameters on the thermal profile and joining mechanism are studied through experiments and numerical simulations.
On the Geometrical Accuracy of High Aspect Ratio Micromilled Pins
Authors: Parenti Paolo , Pagani Luca , Annoni Massimiliano , Colosimo Bianca Maria , Semeraro Quirico
Published: October 2016

Geometrical accuracy of microfeatures in micromilling is strictly related with the choice of cutting parameters. Their correct selection is a challenging task in particular when the target feature geometry is a high aspect ratio feature with tight tolerance requirements. Metallic micromilled pins are adopted in many different industrial applications as in the micromold technology field, in the microelectromechanical systems, and in the biomedical devices and their geometrical accuracy represents a fundamental property for their functionality. This work outlines the connection between the achieved geometrical accuracy and the micromilling parameters and cutting strategies on pins with diameter = 100 μm and height = 2 mm (i.e., aspect ratio = 20). Pin geometrical error features are extracted from three-dimensional optical measurements and then correlated with cutting parameters to support machining process setup. A proper fitting based on Chebyshev functions is applied and a statistical analysis assesses the importance of each deviation component in relation to the imposed cutting conditions. The proposed methodology fills the specific lack in the literature domain about micropin machining and can easily extend to different types of geometrical microfeatures. Finally, correlation between part geometrical errors and machining forces is analyzed. Cutting force analysis is adopted in conventional machining for implementing online geometrical errors assessment or compensation methods. However, this study confirms that the applicability of this approach in high aspect ratio pin micromilling is prevented from the predominant scale-effects and the large part bending that generates a low direct correlation between forces and part geometrical errors.
Microstructure and Fatigue Property of Ti–6Al–4V by Ultrahigh Frequency Pulse Welding
Authors: Yang Mingxuan , Zheng Hao , Qi Bojin , Yang Zhou
Published: October 2016

Butt welding tests of 1.5 mm thickness Ti–6Al–4V were treated by conventional gas tungsten arc welding (C-GTAW) and ultrahigh frequency pulse GTAW (UHFP-GTAW). The low cycle fatigue (LCF) experiments were conducted on the welded joints. The results of fatigue experiment showed that the number of fatigue cycles was increased with UHFP-GTAW. Changes in the microstructure resulting from reduced heat input were expected to enhance the fatigue propagation resistance. The morphology of the martensites in fusion zone was smaller compared to C-GTAW process, and a larger distribution density of basketweave structure was also obtained by UHFP-GTAW. Furthermore, the decreased fatigue crack rate was accompanied as the increased grain boundaries produced by the reduced grain size in fusion zone. Observation of fatigue fractographs revealed that the UHFP-GTAW has obvious slip traces at fatigue initiation sites and more deep secondary cracks in the crack propagation regions associated with the smaller dimples of final fracture zones. The proportion of propagation regions was much larger than C-GTAW. As a result, it can be considered as the representation of the improvement in ductility.
Design and Integrity Evaluation of a Finned-Tube Sodium-to-Air Heat Exchanger in a Sodium Test Facility
Authors: Lee Hyeong-Yeon , Kim Hyungmo , Kim Jong-Bum , Jeong Ji-Young
Published: October 2016

A high-temperature design and an integrity evaluation for a finned-tube sodium-to-air heat exchanger (FHX) in a sodium test facility were conducted based on full 3D finite-element analyses, and comparisons of the design codes were made. A model FHX has been installed in a sodium test facility of sodium thermal-hydraulic experiment loop for finned-tube sodium-to-air heat exchanger (SELFA) for simulating the thermal hydraulic behavior of the FHX unit in the prototype Gen IV sodium-cooled fast reactor (PGSFR). For the design evaluations, ASME Section VIII Div. 2 has been applied for the FHX as a whole. For parts of the FHX operating in the creep regime, nuclear grade elevated temperature design (ETD) codes of ASME Section III Subsection NH and RCC-MRx were additionally applied to evaluate the integrity against creep-fatigue damage. For parts of the FHX operating at low temperature, ASME Section III Subsection NB was applied additionally to evaluate the integrity upon load-controlled stresses and fatigue. The integrity of the FHX was confirmed based on the design evaluations as per the design codes. Code comparisons were made in terms of the chemical compositions, material properties, and conservatism. The conservatism was quantified and compared at the critical low temperature location between ASME Section VIII Div. 2 and ASME-NB, and at the critical high-temperature location between ASME-NH and RCC-MRx.
Vortex-Induced Vibration Characteristics for a Three Dimensional Flexible Tube
Authors: Feng Zhipeng , Zang Fenggang , Zhang Yixiong
Published: October 2016

In order to study the vortex-induced vibration, the three-dimensional unsteady, viscous, incompressible Navier-Stokes equation and LES turbulence model are solved with the finite volume approach, and the dynamic equilibrium equations are discretized by the finite element theory. A three-dimensional numerical model for flexible tube vibration induced by cross flow is proposed. The model realized the fluid-structure interaction with solving the fluid flow and the structure vibration simultaneously. Based on this model, the dynamic behavior and response characteristic of the tube are investigated. Meanwhile, the limit cycle and bifurcation of lift coefficient and displacement are analyzed. Amplitude response, trajectory, phase difference, fluid force coefficient and vortex shedding frequency are obtained. The results reveal that, a quasi-upper branch is found in the present fluid-flexible tube coupling system with high mass-damping and low mass ratio. The three-dimensional flexible tube has a broader synchronization range and the amplitude is higher than elastically mounted two-dimensional rigid tube. In the quasi-upper branch and lower branch regime, the “lock-in” begins. In quasi-upper branch, the lateral amplitude increases with reduced velocity increasing. While in lower branch, the amplitude keeps almost constant. The drag force reaches its peak value before lift. The lift coefficient reaches its maximum value at the switch from initial branch to quasi-upper branch. The phase angle reaches zero under “lock-in” and the dynamic behavior is a periodic motion. There is no bifurcation of lift coefficient and lateral displacement occurred in three dimensional flexible tube submitted to uniform turbulent flow.
Developing and Exploring for Treatment Technology of ADU Wastewater Containing High-Concentration Fluorine and Ammonia-Nitrogen
Authors: Tan Xingxing , Zhao Ning
Published: October 2016

A set of new treatment facilities have been built to deal with the high-concentration of fluorine and ammonia-nitrogen (NH3-N) in wastewater generated from the preparation process of UO2 powder by ADU, whose concentration reaches up to 20g/L and 70g/L, respectively. Compared with various methods and summarized from vast experiences, a three-step technological process has been adopted. Firstly, fluorine is fixed by Ca(OH)2, and the product, CaF2, and other solids are filtered by centrifuge. And the teeny solids in the primary filtrate are precipitated by proper flocculants in pipe chute settling pond. Secondly, the treated wastewater with certain alkalinity is rectified by folded-plate rectifying tower. Meanwhile the ammonia is reused. Finally, adsorbed by specific adsorbent, the fluorine and NH3-N concentration of treated wastewater is further reduced. After numerous experiments and two-year running tests, the process control has been improved. Now, the wastewater treatment capability of the facility can reach 45m3/day. And the concentration of fluorine and NH3-N in the final wastewater is less than 10mg/L and 15mg/L, respectively, which can meet the state wastewater discharge standards. Besides, the concentration of the reused ammonia is raised from 5wt% to 25wt%, and the recovery can reach 99.3%.
Numerical Simulation of Interfacial Phenomenon of Air-Water Adiabatic Intermittent Flow in Helically Coiled Tubes
Authors: Zhu Guangyu , Zhu Hongye
Published: October 2016

Helically coiled tube are widely used as the basic heat transfer elements in steam generators of the next generation reactors, such as HTR-PM (High Temperature Gas-cooled Reactor), IRIS (International Reactor Innovative and Secure) and SMART (System-integrated Modular Advanced Reactor), because of the advantages in reducing space, enhancing heat transfer, accommodating thermal stress and preventing two-phase flow instabilities. Owing to the presence of gravity and centrifugal force that being perpendicular to the main flow, two-phase flow in helically coiled tubes has different features with either vertical flow or horizontal flow. To ensure safety and reliability of the plant, it is necessary to carry out detail investigation on the two-phase flow phenomena and mechanisms in helically coiled tubes. However, less research has been carried out on this subject than on straight tubes. In this work, the upward air-water slug and plug flows in helically coiled tubes have been numerically analyzed based on the computational fluid dynamics (CFD) techniques. Three dimension models of helically coiled tubes with inner diameter of 16 mm, coil diameter of 0.1 and 0.4m, pitch of 0.08 and 0.16m are constructed, for which the structural meshes are generated by software ANSYS ICEM. The gas-liquid interface is captured by the volume of fluid (VOF) approach adopting geo-reconstruction scheme for interface interpolation, which is solved by a pressure-based transient solver in the commercial CFD software ANSYS FLUENT 14.5. Bubble chord length, slug/plug frequency, bubble velocity and void fraction under different superficial velocities have been investigated. The numerical results meet well with the pictures recorded by a high speed camera. It is revealed that in slug regime, the bubbles mainly migrate towards the top and inner wall of the tube due to the combined action of gravity and centrifugal force, leading to a highly asymmetrical internal phase distributions. Meanwhile, the secondary flow in the cross section introduced by the centrifugal force enhances the turbulence and prevents small bubbles to coalescent into enlarged bubbles. Accordingly the intermittent flow regime in helically coiled tubes is narrower than that in straight horizontal tubes. Furthermore, the influences of geometrical parameters on phase distribution characteristics are predicted. The results show that the bubble length will increase along with the increase of the coil diameter or the pitch of the helically coiled tube. And the bubble frequency will increase with the decreasing of the tube coil diameter.
CFD Simulation of Natural Ventilation Performance of the Interim Region in Spent Fuel Dry-Storage System of HTR-PM
Authors: Wang Bing , Wang Jinhua , Jia Haijun
Published: October 2016

The spent fuel dry-storage system of High Temperature Reactor-Pebble bed Modules (HTR-PM) in China is designed to consist of 3 separate regions, with each composed of multiple storage wells. Cold air is distributed to 8 parallel wells in the interim region from a bifurcation chamber, and then heated by vertical placed canisters in each well before gathering in a mixture chamber. In accident condition, the decay heat in interim region will be discharged by open-cycle natural ventilation. In this paper, thermal performance of the interim region by natural ventilation was investigated by a step-by-step scheme. Firstly, the resistance characteristics of wells loaded with different numbers of canisters and bifurcation chamber were studied with CFD code, and were formulated into momentum sources of porous media. Then, equivalent model of the system with porous media regions was employed to simulate the flow distribution of the system. Two different operation conditions (half-loaded condition and full-loaded condition) were studied in this step and hottest well were located. Finally, a refined model of the hottest well with minimized and necessary assumption was employed to investigate the conjugate heat transfer coupled with thermal radiation process, and to obtain the internal temperature profile of the hottest well. The results showed that the total mass flow of natural ventilation is 5.53 kg/s under half-loaded condition (20 canisters, 156.72 kW of decay heat) and 4.83 kg/s under full-loaded condition (40 canisters, 192.37 kW of decay heat). Hottest well was the well-1th under half-loaded condition, where maximal temperatures of concrete walls, steel barrel, canisters and spent fuel pebble bed inside the canister were 86.5 °C, 142.2 °C, 279.5 °C, 484.9 °C, respectively. The results demonstrate that the interim region of dry-storage system satisfies the temperature limitation of component materials in accident condition.
LOCA Simulations of AP1000 With Different Breaks Based on RELAP5
Authors: Hou Xiuqun , Xie Danmei , Cai Lin , Zhang Peng , Tan Jie
Published: October 2016

One of design features of AP1000 is its passive safety system. As the newly designed system, the performance of AP1000 under severe accidents causes a lot of concerns. To prevent or minimize being uncovered of the core fuel during LOCAs, many researchers have devoted themselves to simulate LOCAs. In this paper, based on RELAP5, the model of AP1000 was established and validated. LOCA simulations of AP1000 with different breaks were conducted, including LOCAs both on cold leg and hot leg with the break size of 0.1 ft2 and LOCAs with different break size as 0.01%, 0.1%, 1%, 10%, 20%, 40%, 50% of the cold leg cross section area on cold leg. The result indicates that, for AP1000, LOCA on cold leg is more critical, and the system shows great safety performance under LOCAs with different break sizes on cold leg, especially for LOCA with middle break size because the core decay heat is fully removed by coolant and the cladding temperature decreases soon once the accident happens during the process. The result also reveals that, during the process, the core decay heat is mainly removed by the discharge coolant for large break LOCA, but mainly removed by PRHR HX for small break LOCA.
Kinetic Monte Carlo Simulation of Hydrogen Diffusion in Tungsten
Authors: Yang Xue , Oyeniyi Wasiu O.
Published: October 2016

This research developed a Kinetic Monte Carlo (KMC) method for simulating hydrogen diffusion in tungsten bulk. The KMC inputs such as diffusion paths and energy barriers are taken from DFT calculation results from the literatures. In this simulation model, stable hydrogen interstitial sites in tungsten are the tetrahedral sites on each surface of the bcc lattice, and each site has four tetrahedral neighboring sites, with two neighbors on the same lattice surface and the other two on the adjacent two perpendicular surfaces. A MATLAB script has been developed to perform the diffusion modeling for any given hydrogen concentration and substrate temperature. To compare the simulation results with experiment measurements, modeling configuration of low hydrogen concentration and temperature of 300 K to 2500 K mirroring the experiment conditions was used. The calculated diffusion coefficients at various temperatures match the experiment reference very well. The calculated diffusion coefficients are also fitted to the Arrhenius equation as:

D [m2/s] = 5.59×10−7 exp(−0.426/kBT)
Nuclear, Solar and Desalination Working Together Symbiotically
Authors: Alwashmi Hamad , Kunze Jay F.
Published: October 2016

In many parts of the world, drinking water is not available except through desalination. Most of these areas have an abundance of solar energy, with few cloudy periods. Energy is required for desalination and for producing electricity. Traditionally this energy has been supplied by fossil fuels. However, even in those parts of the world that have abundant fossil fuels, using them for these purposes is being discouraged for two reasons: 1) the emission of greenhouse gases from combustion of fossil fuels, and 2) the higher value of fossil fuels when used for transportation. Nuclear power and solar power are both proposed as replacements for fossil fuels in these locations. Both of these energy systems have high capital costs, and negligible fuel costs (zero for solar) Instead of these two primary forms of energy competing, this paper shows how they can compliment each other, especially where a significant part of the electricity demand is used for desalination.
Analysis of Flashing and Slow Descending Phenomenon in Ring Coelom of Integrated Reactor During LOCA
Authors: Wang Dingqu , Wang Yan , Li Songyang , Jia Haijun , Jin Lina , Wang Xiaohong
Published: October 2016

Integrated reactor has an integrated pressure vessel with all components of the main coolant loop inside. Ring coelom is formed between the pressure vessel and the heat exchanger. Several small-bore pipes are plugged into the ring coelom to attain the coolant. Because of the existence of the isolated ring coelom, slow descending phenomenon of liquid level in the ring coelom takes place during LOCA with a coolant diversion pipe breaking. The phenomenon is analyzed by modelling the reactor during LOCA in Relap5 and one mitigation measure is acquired. As drastic flashing seriously influences the slow descending phenomenon, which enhance the pressure in the ring coelom, we divide the ring coelom into several parts and use Fluent to gain the flashing details. The results of Relap5 and Fluent show good agreement, which proves the flashing and slow descending phenomenon in the ring coelom of integrated reactor is reasonable during LOCA.
Validation of the ATHROC Code With NUPEC Tests
Authors: Chen Yongzheng , Wu Yingwei , Tian Wenxi , Qiu Suizheng , Su Guanghui
Published: October 2016

Xi’an Jiaotong University (XJTU) has developed a containment code called ATHROC (Analysis of Thermal Hydraulic Response of Containment) for the design of a new advanced PWR (Pressurized Water Reactor) in China. In the present work, the well-known NUPEC (NUclear Power Engineering Corporation) tests are simulated to validate the code. NUPEC test M-7-1 and M-4-3 were separately simulated to investigate the mixing effect of hot gas and steam being injected at a low elevation with or without spray cooling in the dome. An analytical model consisting of 26 cells and 67 flow paths was established. In addition, 62 distributed heat structures and 1 lumped heat structure were also modeled in the simulation. The predictions of both simulated tests agree relatively well with the experiment data. The maximum relative errors of predicted temperature for M-7-1 test and M-4-3 test were about 10% and 3%, respectively. The peak pressures of the two tests were about 3.8% and 6.7% overestimated, respectively, and the peak helium concentrations were about 25% and 20% overestimated, respectively. On the other hand, thermal and helium stratification within the containment were well predicted.
Cybersecurity Case for FPGA-Based NPP Instrumentation and Control Systems
Authors: Illiashenko Oleg A. , Broshevan Yevheniia V. , Kharchenko Vyacheslav S.
Published: October 2016

Modern industrial instrumentation and control systems (I&Cs) used in nuclear power plants (NPP) are facing more with cybersecurity threats and vulnerabilities, which were neglected before. Cybersecurity incidents are a subject to grow into more complex attacks with worse consequences than before. The use of field programmable gate arrays (FPGA) in such critical systems causes specific risks for ensuring of safety, as the master-property of such kind of systems, and security as a subordinate property primarily to the NPP reactor trip systems (RTS).

Cybersecurity assessment results of industrial I&Cs are mainly based on subjective assessment of the expert judgment and they do not take into account all features of propagating FPGA technology. Nowadays there is a big gap in understanding how to assess and assure the security of FPGA-based NPP I&Cs (FNI&Cs). Conformance of FNI&Cs to security requirements, their verification to high-level standards often is subjective and depends on particular expert.

Regulatory and certification bodies, developers and end-users of FNI&Cs are missing the understandable methodology for security assurance of such kind of systems taking into account specific context of the operating environment which allows decreasing time-to-market and thus providing benefits for all interested parties.

The paper describes cybersecurity assurance technique of multi-version FNI&Cs. Requirements profile is formulated using the best practices from the following international regulations. The goal of the paper is presentation of the case-based methodology and tool of FNI&Cs cybersecurity assurance based on international regulations. Proposed methodology provides comparable and repeatable process of assurance.
Feeding the Nuclear Safety Culture Pipeline
Authors: Schow Ryan C. , Jevremovic Tatjana
Published: October 2016

The University of Utah Nuclear Engineering Program (UNEP) has established and continues to build a strong nuclear safety culture by developing class and laboratory soft skills training and activities. An effective safety-culture is essential to nuclear safety and can help prevent errors and misconduct by ensuring expectations and consequences are clearly stated and understood. Academic and research reactors present additional challenges as new students are joining the program and nuclear environment for the first time.

The UNEP is leading the way in establishing and building a strong positive nuclear safety culture. Social media and practical training is being developed that is intertwined with class and laboratory work along with integrating industry used tools and software to prepare the future nuclear workforce to meet the needs of the nuclear industry.
Comparative Study on Neutronics Characteristics of a 1500 MWe Metal Fuel Sodium-Cooled Fast Reactor
Authors: Ohgama Kazuya , Aliberti Gerardo , Stauff Nicolas E. , Ohki Shigeo , Kim Taek K.
Published: October 2016

Under the cooperative effort of the Civil Nuclear Energy R&D Working Group within the framework of the U.S.-Japan bilateral, Argonne National Laboratory (ANL) and Japan Atomic Energy Agency (JAEA) have been performing benchmark study using Japan Sodium-cooled Fast Reactor (JSFR) design with metal fuel. In this benchmark study, core characteristic parameters at the beginning of cycle were evaluated by the best estimate deterministic and stochastic methodologies of ANL and JAEA. The results obtained by both institutions are agreed well with less than 200 pcm of discrepancy on the neutron multiplication factor, and less than 3% of discrepancy on the sodium void reactivity, Doppler reactivity, and control rod worth. The results by the stochastic and deterministic were compared in each party to investigate impacts of the deterministic approximation and to understand potential variations in the results due to different calculation methodologies employed. Impacts of the nuclear data libraries were also investigated using a sensitivity analysis methodology.