Rod Location Research Articles

Binary optimization of gold nano-rods for designing an optical modulator

An optical modulator with ultra small plasmonic nano rods that can filter the coherent optical frequency is developed. The performance of optical modulator based on dimmer metal nano rods on the top of silicon waveguides as coherent perfect absorber (CPA) is studied. In the proposed model, the optical modulator is excited by two monochromatic incident plan waves with the same frequencies and two polar angles "$$\uptheta =0$$?=0" and "$$\uptheta =\Pi /2$$?=?/2". When the signal with $$\uptheta =0$$?=0 is applied to the modulator separately, the incident wave transmits from the first path and suppresses for the second one, while when both signals are applied to the modulator simultaneously, the CPA occurs for the first path and the ligthwave transmits from the second one. Therefore for two paths there are two states. "on" state when ligthwave transmitted from each path and "off" state when ligthwave suppressed. In this case two paths consist of different array of nano rods locations. Since the CPA efficiency depends strongly on the number of plasmonic nano rods and the nano rods location, a new efficient binary optimization method based the teaching---learning-based optimization (TLBO) algorithm is proposed to design an optimized array of the plasmonic nano-rods in order to achieve the maximum absorption coefficient in the `off' state and the minimum absorption coefficient in the `on' state. In Binary TLBO, a group of learner consists a matrix with binary entries, control the presence (`1') or the absence (`0') of nano rods in the array.

The Effect of Position of Heated Rod in Tube Banks on the Heat Transfer Coefficient

Heat transfer in flow across a bank of tubes is of a particular importance in the design of heat exchangers. Heat exchangers are used in numerous services and industrial applications. Experimental studies were performed, carried out in cross-flow tube banks. They contain copper heated rod and 17 Aluminum rods arranged in the form of staggered and at arrange of Reynolds number 2700 to 21530. The experimental results indicated that the location of the heated rod in the work section affects the value of heat transfer coefficient thus this value is increased when the heated rod location changes both the y and x-directions. The experimental data revealed good agreement with Zukauskas correlation in four columns.

Safety assessment of U–Mo fuel mini plates irradiated in HANARO reactor

Neutronic and thermal hydraulic characteristics of U–Mo fuel mini plates irradiated in the HANARO reactor were analyzed for the safety assessment of these plates. A total of eight fuel plates were double-stacked; each stack contained three 8.0gU/cc U–7Mo fuel plates and one 6.5gU/cc U–7Mo fuel plate. The neutronic and thermal hydraulic analyses were carried out using the MCNP code and TMAP code, respectively. The core status used in the study was the equilibrium core, and four Control Absorber Rod (CAR) locations were considered: 350mm, 450mm, 550mm, and 650mm away from the bottom of the core. For the fuels in the lower stack, the maximum heat flux was found at the CAR located at 450mm. For the fuels in the upper stack, the maximum heat flux was found at the CAR located at 650mm. The axial power distributions for the upper and lower stacks were selected on the basis of thermal margin analyses. A mock-up irradiation target assembly was designed and tested at the out-of-pile test facility to measure the flow rate through the irradiation site, given that the maximum flow rate through the irradiation site at the HANARO reactor is limited to 12.7kg/s. For conservative analyses, measurement and correlation uncertainties and engineering hot channel factors were considered. During normal operation, the minimum ONB temperature margins for the lower and upper stacks are 41.6°C and 31.8°C, respectively. This means that boiling does not occur. However, boiling occurs during the limiting accidents. Nevertheless, the fuel integrity is maintained since the minimum DNBR are 1.96 for the Reactivity Insertion Accident (RIA) and 2.10 for the Locked Rotor Accident (LRA). From the neutronic and thermal hydraulic analyses of the U–Mo fuel mini plates irradiated in the HANARO reactor, it is concluded that boiling does not occur during normal operation and that the fuel integrity is maintained during limiting accidents.

Solutions Stability of Initial Boundary Problem, Modeling of Dynamics of Some Discrete Continuum Mechanical System

The solution stability of an initial boundary problem for a linear hybrid system of differential equations, which models the rotation of a rigid body with two elastic rods located in the same plane is studied in the paper. To an axis passing through the mass center of the rigid body perpendicularly to the rods location plane is applied the stabilizing moment proportional to the angle of the system rotation, derivative of the angle, integral of the angle. The external moment provides a feedback. A method of studying the behavior of solutions of the initial boundary problem is proposed. This method allows to exclude from the hybrid system of differential equations partial differential equations, which describe the dynamics of distributed elements of a mechanical system. It allows us to build one equation for an angle of the system rotation. Its characteristic equation defines the stability of solutions of all the system. In the space of feedback-coefficients the areas that provide the asymptotic stability of solutions of the initial boundary problem are built up.

Improvements of two-pass core design for super fast reactor

Improvements of two-pass core design of Super critical-water cooled fast reactor (Super FR) are proposed. The core height has been shortened; assembly pitch is enlarged to take Control Rod (CR) design into account. Well-coupled fuel loading pattern is proposed, number of control rods location are limited only in second flow pass assemblies due to current flow pattern. Fuel shuffling is also confined within each own flow pass because of the different structure of assemblies. CR withdrawal is considered during the operation, satisfactory radial and axial power distribution can be achieved by implementing appropriate CR withdrawal strategy. Results suggest that all the design target, criteria and limits are satisfied in terms of average coolant outlet temperature, maximum linear heat generation rate (MLHGR), maximum cladding surface temperature (MCST) as well as core shutdown margin, negative coolant void reactivity coefficient and positive coolant density reactivity coefficient in all coolant density range.

Measurement of void fraction in flow boiling of ZnO–water nanofluids using image processing technique

In recent years, nanofluids have been an active area of research in many engineering applications, especially for nuclear reactor safety systems due to their enhanced thermal properties as a coolant. In this study, experiments were performed in subcooled flow boiling of water and ZnO–water nanofluids with different nanoparticle concentrations (0.001–0.01vol.%) in horizontal annulus at heat fluxes varying from 100 to 550kW/m2 and flow rates from 0.1 to 0.175lps at 1bar inlet pressure and constant subcooling of 20°C to determine the void fraction by image processing technique. Parametric effects of nanoparticle volume fraction, heat flux, flow rate and axial location of heater rod on void fraction were studied. Bubble images during flow boiling were captured with high speed visualization and analyzed by National Instruments IMAQ Vision Builder 6.1 image processing software. Results show that void fraction decreases up to 86% with the use of nanofluid in place of water and it also decreases with increasing nanoparticle concentration and flow rate, whereas increase in heat flux and axial location of heater rod have opposite effect.

Finite Element Analysis of Free Expansion of Coronary Stent Based on ANSYS Workbench

Undertaking the 316L stainless steel as a medical stent material and the coronary stent structure as the research object, ANSYS Workbench12.0 is used to simulate the free expansion process of coronary stent by two expansion methods. Finite element analysis is used to solve such problems as deformation behaviour of the stent, mechanical behaviour as well as nonlinear problems of the stent and balloon interaction during the free expansion process. The simulation results show that the stent and balloon interaction process will appear slip phenomenon, the stent shortening in the axial direction and elongating in the radial direction, and that the arc supporting rod location of the stent is the main area of the maximum stress. These can provide a scientific reference for the next new stent design and optimization.

Research and Applications of a Plane Embedded Combined Element Model Considering Bond and Slip

It is one of the most important issues for finite element analysis of lining structures that how to describe anchor rod reasonably and effectively and simulate the interaction between rod and concrete or rock. Virtual nodes are constructed in concrete/rock element at the ends of anchor rod and bond-slip element is set between virtual nodes and beam element which describes anchor rod. An embedded combined element with bond slip and shear deformation is established through the transformation of nodal force at nodes of bond-slip element to those of concrete/rock element via shape functions. The element is convenient for meshing element because the location and direction of anchor rod are not necessary to be considered. Meanwhile, the element has the advantage of low computing cost. Finally, the validity and efficiency are verified by numerical examples.

Use of a hydraulic brake as a source of thermal energy for the railway rolling stock

Introduction: In this paper the braking issues of passenger trains which have a great speed and frequent stops are examines. Problem statement: These processes are ехpensive and have big energy losses. The proposed solution to the problem: The kinetic energy of braking prosses propose to turn into thermal energy of heating fluid. For this purpose special hydraulic brake is proposed. The brake is connected with the wheel carriage pairs. The process is based on the energy dissipation in liqid when the disks with spikes rotate in it. Because the real liquid has friction and viscosity, it will be heat up, when the mechanical parts of the hydraulic brake are moved in it. The design, operating principle and characteristics of the hydraulic brake are proposed. Transmission of kinetic energy of carriage motion to brake system executed by mechanical clutches. It connected with the wheel pair and transmitting the energy the wheels rotation to hydraulic brake discs. The cylindrical rods are installed on the discs. Rods location fits the profile of the curved centrifugal pump vanes. As result, the fluid heatind prosess by rotatinge discs with rods take place also at the same time with the liquid pumping through the inner volume of brake system.Conclusions: Affordable passenger carriage braking dynamic is achieved by varying the size and number of rods. The heated liquid may be subsequently used for household needs and for heating the passenger carriage.

The effect of fuel rod oxidation on PCMI-induced fuel failure

It was found in a one of the PWRs operating in Korea that a few three cycle-burned Zry-4 fuel assemblies which were loaded in a core center region at control bank positions were leaking. The leaking cycle has experienced a few reactor trips and some fuel rods started to leak at about a month after a power ramp following the second reactor trip. To investigate a root cause of such fuel failure as well as to examine intact and leak rod oxidation behaviors, one intact and one leaking fuel rods were selected from one intact and one failed three cycle-burned fuel assemblies, respectively, and in parallel one intact fuel rod was selected from a two cycle-burned fuel assembly to examine the effect of burnup on fuel rod oxidation and cladding stress during the power ramp. The maximum oxide thicknesses for the intact two cycle-burned and three cycle-burned fuel rods were measured to be about 70 and 140 μm, respectively, whereas that for the leaking three cycle-burned fuel rod to be about 200 μm. The leaking fuel rods generated a very sharp increase in oxide thickness in the fuel rod upper region having a relatively high axial power, resulting in through-wall axial cracks. The root cause of the fuel rod leaks was evaluated to be the pellet-clad mechanical interaction (PCMI)-induced failure combined with excessive Zry-4 oxidation and cladding stress, based on the evaluations of pellet-clad friction coefficient-dependent cladding hoop stresses after the power ramp following the second trip, measured oxide thicknesses and axial cracks on the cladding surface, a fuel leak initiation time and failed fuel rod locations at the control bank positions.

Reactor physics ideas for large scale utilization of thorium in gas cooled reactors

The physics principles for maximizing the fertile to fissile conversion were used in developing reactor concepts for large scale utilization of thorium in thermal and fast reactors ( Jagannathan & Pal, 2006; Jagannathan et al., 2008). It is recognized that these principles are very well suited for ‘He’ gas cooled reactors with graphite moderator since both helium gas coolant and the graphite moderator have low neutron absorption characteristics and thus gives better neutron economy. In this paper, these ideas are applied to the High Temperature Test Reactor (HTTR) core of Japan to assess its advantage over the present day gas cooled reactors. HTTR is helium cooled and graphite moderated system. Significant amount of thorium has been loaded in the HTTR core with some minimal changes in the existing core design. The modified design is called HTTR-M core.In the HTTR-M core, the fuel is changed from enriched UO 2 fuel to Pu in ThO 2 fuel. The locations of boron type burnable poison rods within each fuel assembly of HTTR are replaced by one cycle irradiated thoria rods. Also, the B 4C type control assembly around the HTTR core is replaced by fresh seedless thorium assembly. The fertile thoria assembly are scattered uniformly in the HTTR-M core. The equilibrium core of HTTR-M shows very small burnup reactivity swing. The core excess reactivity is ∼18 mk at BOC and reduces to 1 mk at 660 days. It is interesting to note that this small reactivity change is intrinsically achieved by the choice of seed and fertile dimensions and their contents without the use of burnable poison rods or mechanical control rods which are used in HTTR core. The burnup reactivity swing in the latter after using burnable poison is ∼100 mk. The fissile seed inventory ratio (FIR) in a fuel cycle is 0.90 as compared with 0.717 of HTTR core. Since 233U is a better fissile nuclide with highest ‘η’ value in thermal range, the above conversion ratio can be regarded as quite good.

Flexural and Shear Strength of Granite Reinforced by Metal Rods

This paper investigates feasibility of reinforcement method for fractured granite of slab type and beam members used as components of old stone masonry pagodas. Investigation of the effect of reinforcement to flexural and shear strength is performed using the concept for the high strength concrete since the mechanical properties of granite are similar to properties of high strength of concrete. In this experimental program two types of notched specimens are intended for failures with shear and flexural cracks. Intended fractured specimens are reinforced by metal rods, so called pinning method. The rods are inserted in holes and bonded with inorganic cement. The metal rods are supposed to transfer forces by tensile resistance in flexure and dowel action in shear. Increase in shear and flexural capacities and ductile behavior after sudden yielding of the metal rods are observed. The final failure cracks in reinforced specimens occurred different from interfaces along the original cracks. Locations of metal rods, their numbers, and construction of anchored rod are main variables to be examined for guidelines for reinforcement methods.

Complications of Growing-Rod Treatment for Early-Onset Scoliosis

Previous reports have indicated high complication rates associated with non-fusion surgery in patients with early-onset scoliosis. This study was performed to evaluate the clinical and radiographic complications associated with growing-rod treatment. Data from the multicenter Growing Spine Study Group database were evaluated. Inclusion criteria were growing-rod treatment for early-onset scoliosis and a minimum of two years of follow-up. Patients were divided into treatment groups according to rod type (single or dual) and rod location (subcutaneous or submuscular). Complications were categorized as wound, implant, alignment, and general (surgical or medical). Surgical procedures were classified as planned and unplanned. Between 1987 and 2005, 140 patients met the inclusion criteria and underwent a total of 897 growing-rod procedures. The mean age at the initial surgery was six years, and the mean duration of follow-up was five years. Eighty-one (58%) of the 140 patients had a minimum of one complication. Nineteen (27%) of the seventy-one patients with a single rod had unplanned procedures because of implant complications, compared with seven (10%) of the sixty-nine patients with dual rods (p ≤ 0.05). Thirteen (26%) of the fifty-one patients with subcutaneous rod placement had wound complications compared with nine of the eighty-eight patients (10%) with submuscular rod placement (p ≤ 0.05). The patients with subcutaneous dual rods had more wound complications, more prominent implants, and more unplanned surgical procedures than did those with submuscular dual rods (p ≤ 0.05). The risk of complications occurring during the treatment period decreased by 13% for each year of increased patient age at the initiation of treatment. The complication risk increased by 24% for each additional surgical procedure performed. Regardless of treatment modality, the management of early-onset scoliosis is prolonged; therefore, complications are frequent and should be expected. Complications can be reduced by delaying initial implantation of the growing rods if possible, using dual rods, and limiting the number of lengthening procedures. Submuscular placement reduces wound and implant-prominence complications and reduces the number of unplanned operations.

Benchmark of Computational Fluid Dynamics Simulations Using Temperatures Measured Within Enclosed Vertical and Horizontal Arrays of Heated Rods

Experiments and computational fluid dynamics/radiation heat transfer simulations of an 8 × 8 array of heated rods within an air-filled aluminum enclosure are performed. This configuration represents a region inside the channel of a boiling water reactor fuel assembly between two consecutive spacer plates. The rods are oriented horizontally or vertically to represent transport or storage conditions. The measured and simulated rod temperatures are compared for three different rod heat generation rates to assess the accuracy of the simulation technique. Simulations show that temperature gradients in the air are much steeper near the enclosure walls than they are near the center of the rod array. The measured temperatures of rods at symmetric locations are not identical, and the difference is larger for rods close to the wall than for those far from it. Small but uncontrolled deviations of the rod positions away from the design locations may cause these differences. The simulations reproduce the measured temperature profiles. For a total rod heat generation rate of 300 W, the maximum rod-to-enclosure temperature difference is 150°C. Linear regression shows that the simulations slightly but systematically overpredict the hotter rod temperatures but underpredict the cooler ones. For all rod locations, heat generation rates, and rod orientations, 95% of the simulated temperatures are within 11°C of the correlation values. For the hottest rods, which reside in the center of the domain where the air temperature gradients are small, 95% of the simulated temperatures are within 4.3°C of the correlation values. These results can be used to assess the accuracy of using simulations to design spent nuclear fuel transport and storage systems.

Free vibration analysis of a rotating beam with nonlinear spring and mass system

Free, out of plane vibration of a rotating beam with nonlinear spring–mass system has been investigated. The nonlinear constraint is connected to the beam between two points on the beam through a rigid rod. Formulation of the equation of motion is obtained starting from transverse/axial coupling through axial strain. Solution is obtained by applying method of multiple time scale directly to the nonlinear partial differential equations and the boundary conditions. The results of the linear frequencies match well with those obtained in open literature. Subsequent nonlinear study indicates that there is a pronounced effect of spring and its mass. The influence of rigid rod location on frequencies is also investigated on nonlinear frequencies of rotating beam.

04/00222 Salt-mudstones and rock-salt suitabilities for radioactive-waste storage systems: rheological properties: Slizowski, J, and Lankof, L. Applied Energy, 2003, 75, (1–2), 137–144

Neutronic and thermal hydraulic characteristics of U–Mo fuel mini plates irradiated in the HANARO reactor were analyzed for the safety assessment of these plates. A total of eight fuel plates were double-stacked; each stack contained three 8.0 gU/cc U–7Mo fuel plates and one 6.5 gU/cc U–7Mo fuel plate. The neutronic and thermal hydraulic analyses were carried out using the MCNP code and TMAP code, respectively. The core status used in the study was the equilibrium core, and four Control Absorber Rod (CAR) locations were considered: 350 mm, 450 mm, 550 mm, and 650 mm away from the bottom of the core. For the fuels in the lower stack, the maximum heat flux was found at the CAR located at 450 mm. For the fuels in the upper stack, the maximum heat flux was found at the CAR located at 650 mm. The axial power distributions for the upper and lower stacks were selected on the basis of thermal margin analyses. A mock-up irradiation target assembly was designed and tested at the out-of-pile test facility to measure the flow rate through the irradiation site, given that the maximum flow rate through the irradiation site at the HANARO reactor is limited to 12.7 kg/s. For conservative analyses, measurement and correlation uncertainties and engineering hot channel factors were considered. During normal operation, the minimum ONB temperature margins for the lower and upper stacks are 41.6 °C and 31.8 °C, respectively. This means that boiling does not occur. However, boiling occurs during the limiting accidents. Nevertheless, the fuel integrity is maintained since the minimum DNBR are 1.96 for the Reactivity Insertion Accident (RIA) and 2.10 for the Locked Rotor Accident (LRA). From the neutronic and thermal hydraulic analyses of the U–Mo fuel mini plates irradiated in the HANARO reactor, it is concluded that boiling does not occur during normal operation and that the fuel integrity is maintained during limiting accidents.

Property Transformation of Thermotropic Liquid Crystals Polymers

The advent of commercially available thermotropic liquid crystals polymers has led to novel uses of these plastics in the astronautics community. During the course of research, a fundamental property, termed polymers annealing, was empirically discovered, whereby thermal and chemical resistance of certain thermotropes are increased dramatically by a defined heat cycle after molding. A fundamental study of this annealing phenomenon has shown it to be a function of both rigid rod location and intermolecular forces. X-ray diffraction and atomic force microscopy results are shown to help in understanding the complex structure and surface morphology.

FORMOSA-B: A Boiling Water Reactor In-Core Fuel Management Optimization Package III

As part of the continuing development of the boiling water reactor in-core fuel management optimization code FORMOSA-B, the cold shutdown margin (SDM) constraint evaluator has been improved. The SDM evaluator in FORMOSA-B had been a first-order accurate Rayleigh quotient variational technique. It was deemed unreliable for difficult perturbed loading patterns (LPs) and thus was replaced by a high-fidelity, robust, computationally efficient evaluator. The new model is based on the solution of the one-group diffusion equation using approximate albedo boundary conditions for a three-dimensional, variable axial node, 10 × 10 assembly subregion around the stuck rod location. The fidelity and robustness of the model are first demonstrated by performing calculations on difficult perturbed LPs and for different plant cores. It is shown that the SDM reactivity is estimated within 40 pcm for the highest worth rod and that the speedup factors are 50 to 100 for small cores (and even more for larger cores) in comparison to the full-core three-dimensional simulations. Next, the successful implementation of the model in imposing the SDM constraint for FORMOSA-B’s adaptive simulated annealing (SA)-based optimization strategy is presented. The results demonstrate SA’s ability to remove large SDM violations (>700 pcm) along with thermal margin and critical flow constraint violations. Finally, the importance of having the SDM constraint on during optimization is shown by comparing results with a simulation in which the constraint is off.

Brace Rods for Codominant Stems: Installation Location and Breaking Strength

The location at which brace rods should be installed to reduce the risk of breakage in codominant stems traditionally has been below the crotch. In this study, codominant stems were pulled apart with measured force to determine if crotch strength was increased by installing a rod above the crotch rather than in the traditional rod location below the junction. With both red oak (Quercus rubra) and red maple (Acer rubrum), the strength of the codominant stem was increased significantly by installing the rod above the crotch a distance equal to the diameter of one of the stems. Brass rods tended to fail more than steel rods in oak but may be useful in small, weakerwooded trees.

Influence of a Downstream Located Obstacle on Transonic Turbine Cascade Flow

The effect of a downstream obstacle (rod of 10 mm diameter) on a turbine blade channel flow is investigated experimentally. Variations of the blade life coefficent in function of the rod location are determined. The flow is visualised by means of the schlieren method. Large differences of the channel and corresponding pressure distributions in the trailing part of the blade surface are noted due to the flow-obstacle interaction