Savoldelli, James; Tomback, Drew; Savoldelli, Hugh
2017-02-01
In this work, the objective is to examine a novel approach on the biodegradability of polystyrene is examined. A two-step method for the degradation of polystyrene to chemically useful products has been devised. Initially, polystyrene is liquefied via a thermal degradation procedure predominantly into styrene monomers at low temperatures and left to cool down. Application of microorganisms in a second step targets the breaking of the polymer into smaller organic molecules. Microorganisms tested were Rhodococcus zopfii stoecker, Enterococcus faecalis, Pseudomonas putida and Salmonella with the last two being the most effective. A third step is required to treat the organic products accordingly. The suggested method exhibits total conversion of polystyrene. While the method has only been examined on a small scale, its potential advantages for the recycling of polystyrene waste, are minimized energy costs due to low temperatures of thermal treatment used and the extremely fast degradation kinetics observed. Copyright © 2016 Elsevier Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
Xiaohong Wu
2012-01-01
Full Text Available A novel two-step technique is introduced to synthesize BaSn(OH6 nanorods. The method involves the preparation of precursor Na2Sn(OH6 crystals in aqueous solution via hydrothermal method and the ion-exchange reaction between Na2Sn(OH6 crystals and Ba2+ solution that followed, assisted by ultrasonic treatment. The BaSn(OH6 nanorods array are formed due to the split of plate-formed Na2Sn(OH6 during the ion-exchange treatment. The influence of the surfactant on the growth of the one-dimensional (1D BaSn(OH6 nanostructures is investigated. In addition, the powder BaSnO3 has been obtained by thermal treatment at 450°C for 5 h under inert gas protecting condition using BaSn(OH6 nanorods as precursor. The 1D shape of BaSn(OH6 was retained after thermal treatment.
Directory of Open Access Journals (Sweden)
Marija Macenić
2018-01-01
Full Text Available At three locations in Zagreb, classical and extended thermal response test (TRT was conducted on installed coaxial heat exchangers. With classic TR test, thermogeological properties of the ground and thermal resistance of the borehole were determined at each location. It is seen that thermal conductivity of the ground varies, due to difference in geological profile of the sites. In addition, experimental research of steady-state thermal response step test (SSTRST was carried out to determine heat rejection rates for passive and active cooling in steady state regime. Results showed that heat rejection rate is only between 8-11 W/m, which indicates that coaxial system is not suitable for passive cooling demands. Furthermore, the heat pump in passive cooling mode uses additional plate heat exchanger where there is additional temperature drop of working fluid by approximately 1,5 °C. Therefore, steady-state rejection rate for passive cooling is even lower for a real case project. Coaxial heat exchanger should be always designed for an active cooling regime with an operation of a heat pump compressor in a classical vapour compression refrigeration cycle.
Thermal neutral format based on the step technology
Almazan, P. Planas; Legal, J. L.
1995-01-01
The exchange of models is one of the most serious problems currently encountered in the practice of spacecraft thermal analysis. Essentially, the problem originates in the diversity of computing environments that are used across different sites, and the consequent proliferation of native tool formats. Furthermore, increasing pressure to reduce the development's life cycle time has originated a growing interest in the so-called spacecraft concurrent engineering. In this context, the realization of the interdependencies between different disciplines and the proper communication between them become critical issues. The use of a neutral format represents a step forward in addressing these problems. Such a means of communication is adopted by consensus. A neutral format is not directly tied to any specific tool and it is kept under stringent change control. Currently, most of the groups promoting exchange formats are contributing with their experience to STEP, the Standard for Exchange of Product Model Data, which is being developed under the auspices of the International Standards Organization (ISO 10303). This paper presents the different efforts made in Europe to provide the spacecraft thermal analysis community with a Thermal Neutral Format (TNF) based on STEP. Following an introduction with some background information, the paper presents the characteristics of the STEP standard. Later, the first efforts to produce a STEP Spacecraft Thermal Application Protocol are described. Finally, the paper presents the currently harmonized European activities that follow up and extend earlier work on the area.
Methods of forming thermal management systems and thermal management methods
Gering, Kevin L.; Haefner, Daryl R.
2012-06-05
A thermal management system for a vehicle includes a heat exchanger having a thermal energy storage material provided therein, a first coolant loop thermally coupled to an electrochemical storage device located within the first coolant loop and to the heat exchanger, and a second coolant loop thermally coupled to the heat exchanger. The first and second coolant loops are configured to carry distinct thermal energy transfer media. The thermal management system also includes an interface configured to facilitate transfer of heat generated by an internal combustion engine to the heat exchanger via the second coolant loop in order to selectively deliver the heat to the electrochemical storage device. Thermal management methods are also provided.
Thermal management systems and methods
Gering, Kevin L.; Haefner, Daryl R.
2006-12-12
A thermal management system for a vehicle includes a heat exchanger having a thermal energy storage material provided therein, a first coolant loop thermally coupled to an electrochemical storage device located within the first coolant loop and to the heat exchanger, and a second coolant loop thermally coupled to the heat exchanger. The first and second coolant loops are configured to carry distinct thermal energy transfer media. The thermal management system also includes an interface configured to facilitate transfer of heat generated by an internal combustion engine to the heat exchanger via the second coolant loop in order to selectively deliver the heat to the electrochemical storage device. Thermal management methods are also provided.
Thickness measurement by two-sided step-heating thermal imaging
Li, Xiaoli; Tao, Ning; Sun, J. G.; Zhang, Cunlin; Zhao, Yuejin
2018-01-01
Infrared thermal imaging is a promising nondestructive technique for thickness prediction. However, it is usually thought to be only appropriate for testing the thickness of thin objects or near-surface structures. In this study, we present a new two-sided step-heating thermal imaging method which employed a low-cost portable halogen lamp as the heating source and verified it with two stainless steel step wedges with thicknesses ranging from 5 mm to 24 mm. We first derived the one-dimensional step-heating thermography theory with the consideration of warm-up time of the lamp, and then applied the nonlinear regression method to fit the experimental data by the derived function to determine the thickness. After evaluating the reliability and accuracy of the experimental results, we concluded that this method is capable of testing thick objects. In addition, we provided the criterions for both the required data length and the applicable thickness range of the testing material. It is evident that this method will broaden the thermal imaging application for thickness measurement.
Neutronics methods for thermal radiative transfer
International Nuclear Information System (INIS)
Larsen, E.W.
1988-01-01
The equations of thermal radiative transfer are time discretized in a semi-implicit manner, yielding a linear transport problem for each time step. The governing equation in this problem has the form of a neutron transport equation with fission but no scattering. Numerical methods are described, whose origins lie in neutron transport, and that have been successfully adapted to this new problem. Acceleration methods that have been developed specifically for the radiative transfer problem, but may have generalizations applicable in neutronics problems, are also discussed
STEP wastewater treatment: a solar thermal electrochemical process for pollutant oxidation.
Wang, Baohui; Wu, Hongjun; Zhang, Guoxue; Licht, Stuart
2012-10-01
A solar thermal electrochemical production (STEP) pathway was established to utilize solar energy to drive useful chemical processes. In this paper, we use experimental chemistry for efficient STEP wastewater treatment, and suggest a theory based on the decreasing stability of organic pollutants (hydrocarbon oxidation potentials) with increasing temperature. Exemplified by the solar thermal electrochemical oxidation of phenol, the fundamental model and experimental system components of this process outline a general method for the oxidation of environmentally stable organic pollutants into carbon dioxide, which is easily removed. Using thermodynamic calculations we show a sharply decreasing phenol oxidation potential with increasing temperature. The experimental results demonstrate that this increased temperature can be supplied by solar thermal heating. In combination this drives electrochemical phenol removal with enhanced oxidation efficiency through (i) a thermodynamically driven decrease in the energy needed to fuel the process and (ii) improved kinetics to sustain high rates of phenol oxidation at low electrochemical overpotential. The STEP wastewater treatment process is synergistic in that it is performed with higher efficiency than either electrochemical or photovoltaic conversion process acting alone. STEP is a green, efficient, safe, and sustainable process for organic wastewater treatment driven solely by solar energy. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Method for measuring thermal properties using a long-wavelength infrared thermal image
Walker, Charles L [Albuquerque, NM; Costin, Laurence S [Albuquerque, NM; Smith, Jody L [Albuquerque, NM; Moya, Mary M [Albuquerque, NM; Mercier, Jeffrey A [Albuquerque, NM
2007-01-30
A method for estimating the thermal properties of surface materials using long-wavelength thermal imagery by exploiting the differential heating histories of ground points in the vicinity of shadows. The use of differential heating histories of different ground points of the same surface material allows the use of a single image acquisition step to provide the necessary variation in measured parameters for calculation of the thermal properties of surface materials.
Thermal sensation and thermophysiological responses with metabolic step-changes
DEFF Research Database (Denmark)
Goto, Tomonobu; Toftum, Jørn; deDear, Richard
2006-01-01
This study investigated the effect on thermal perception and thermophysiological variables of controlled metabolic excursions of various intensities and durations. Twenty-four subjects alternately were seated on a chair or exercised by walking on a treadmill at a temperature predicted to be neutral...... at sedentary activity. In a second experimental series, subjects alternated between rest and exercise as well as between exercise at different intensities at two temperature levels. Measurements comprised skin and oesophageal temperatures, heart rate and subjective responses. Thermal sensation started to rise...... or decline immediately (within one minute) after a change of activity, which means that even moderate activity changes of short duration affect thermal perceptions of humans. After approximately 15-20 min under constant activity subjective thermal responses approximated the steady-state response...
Lively, Brooks; Kumar, Sandeep; Tian, Liu; Li, Bin; Zhong, Wei-Hong
2011-05-01
In this study we report the advantages of a 2-step method that incorporates an additional process pre-conditioning step for rapid and precise blending of the constituents prior to the commonly used melt compounding method for preparing polycarbonate/oxidized carbon nanofiber composites. This additional step (equivalent to a manufacturing cell) involves the formation of a highly concentrated solid nano-nectar of polycarbonate/carbon nanofiber composite using a solution mixing process followed by melt mixing with pure polycarbonate. This combined method yields excellent dispersion and improved mechanical and thermal properties as compared to the 1-step melt mixing method. The test results indicated that inclusion of carbon nanofibers into composites via the 2-step method resulted in dramatically reduced ( 48% lower) coefficient of thermal expansion compared to that of pure polycarbonate and 30% lower than that from the 1-step processing, at the same loading of 1.0 wt%. Improvements were also found in dynamic mechanical analysis and flexural mechanical properties. The 2-step approach is more precise and leads to better dispersion, higher quality, consistency, and improved performance in critical application areas. It is also consistent with Lean Manufacturing principles in which manufacturing cells are linked together using less of the key resources and creates a smoother production flow. Therefore, this 2-step process can be more attractive for industry.
Ablative Thermal Response Analysis Using the Finite Element Method
Dec John A.; Braun, Robert D.
2009-01-01
A review of the classic techniques used to solve ablative thermal response problems is presented. The advantages and disadvantages of both the finite element and finite difference methods are described. As a first step in developing a three dimensional finite element based ablative thermal response capability, a one dimensional computer tool has been developed. The finite element method is used to discretize the governing differential equations and Galerkin's method of weighted residuals is used to derive the element equations. A code to code comparison between the current 1-D tool and the 1-D Fully Implicit Ablation and Thermal Response Program (FIAT) has been performed.
Thermal analysis of externally pressurised step bearing including ...
African Journals Online (AJOL)
A numerical study has been done for externally pressurized circular step thrust bearing lubricated with incompressible fluid with finely dispersed air bubbles taking into consideration the variation in lubricant physical properties due to temperature and pressure variation in the fluid film. Effect of misalignment / tilt and coning ...
Full-step interior-point methods for symmetric optimization
Gu, G.
2009-01-01
In [SIAM J. Optim., 16(4):1110--1136 (electronic), 2006] Roos proposed a full-Newton step Infeasible Interior-Point Method (IIPM) for Linear Optimization (LO). It is a primal-dual homotopy method; it differs from the classical IIPMs in that it uses only full steps. This means that no line searches
An improved 4-step commutation method application for matrix converter
DEFF Research Database (Denmark)
Guo, Yu; Guo, Yougui; Deng, Wenlang
2014-01-01
A novel four-step commutation method is proposed for matrix converter cell, 3 phase inputs to 1 phase output in this paper, which is obtained on the analysis of published commutation methods for matrix converter. The first and fourth step can be shorter than the second or third one. The discussed...... method here is implemented by programming in VHDL language. Finally, the novel method in this paper is verified by experiments....
Energy Technology Data Exchange (ETDEWEB)
Geffray, Clotaire Clement
2017-03-20
The work presented here constitutes an important step towards the validation of the use of coupled system thermal-hydraulics and computational fluid dynamics codes for the simulation of complex flows in liquid metal cooled pool-type facilities. First, a set of methods suited for uncertainty and sensitivity analysis and validation activities with regards to the specific constraints of the work with coupled and expensive-to-run codes is proposed. Then, these methods are applied to the ATHLET - ANSYS CFX model of the TALL-3D facility. Several transients performed at this latter facility are investigated. The results are presented, discussed and compared to the experimental data. Finally, assessments of the validity of the selected methods and of the quality of the model are offered.
Thermal fatigue in mixing tees: A step by step simplified procedure
International Nuclear Information System (INIS)
Faidy, Claude
2003-01-01
Following the CIVAUX 1 incident of a leak on RHR system, EDF has developed a step by step procedure to screen and analyse similar locations: mixing tees with long duration at high ΔT between the 2 fluids. The paper present the procedure, the background of the methodology and few R and D work that support this procedure. The procedure is based on: screening criteria on maximum DT and minimum duration. screening criteria without any duration consideration, only DT and material. a simplified and conservative estimation of a usage factor. a detailed analysis of usage factor and crack growth rate, based on specific data collection of operating transients. Around that procedure EDF launched an R and D program on fatigue curves and fatigue reduction factors for high cycle fatigue. The procedure is compared with field experience and recent R and D fatigue tests. (author)
Some generalized two-step block hybrid Numerov method for ...
African Journals Online (AJOL)
This paper proposes a class of generalized two-step Numerov methods, a block hybrid type for the direct solution of general second order ordinary differential equations. Both the main method and additional methods were derived via interpolation and collocation procedures. The basic properties of zero stability, ...
Midpoint two- steps rule for the square root method | Uwamusi ...
African Journals Online (AJOL)
We present a method “Midpoint-Two-Steps rule” for the square root functional iteration for enclosing zeros of a polynomial. The method combines classical square root method in its formulation a variant of the approach adopted by (Wang and WU,1985) where a Gauss-Siedel updating formula was used to accelerate the ...
Zhu, Jiawei; Zhang, Guangru; Liu, Gongping; Liu, Zhengkun; Jin, Wanqin; Xu, Nanping
2017-05-01
The practical applications of perovskite hollow fibers (HFs) are limited by challenges in producing these easily, cheaply, and reliably. Here, a one-step thermal processing approach is reported for the efficient production of high performance perovskite HFs, with precise control over their cation stoichiometry. In contrast to traditional production methods, this approach directly uses earth-abundant raw chemicals in a single thermal process. This approach can control cation stoichiometry by avoiding interactions between the perovskites and polar solvents/nonsolvents, optimizes sintering, and results in high performance HFs. Furthermore, this method saves much time and energy (≈ 50%), therefore pollutant emissions are greatly reduced. One successful example is Ba0.5Sr0.5Co0.8Fe0.2O3-δ HFs, which are used in an oxygen-permeable membrane. This exhibits high oxygen permeation flux values that exceed desired commercial targets and compares favorably with previously reported oxygen-permeable membranes. Studies on other perovskites have produced similarly successful results. Overall, this approach could lead to energy efficient, solid-state devices for industrial application in energy and environmental fields. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Strong Stability Preserving Two-step Runge–Kutta Methods
Ketcheson, David I.
2011-12-22
We investigate the strong stability preserving (SSP) property of two-step Runge–Kutta (TSRK) methods. We prove that all SSP TSRK methods belong to a particularly simple subclass of TSRK methods, in which stages from the previous step are not used. We derive simple order conditions for this subclass. Whereas explicit SSP Runge–Kutta methods have order at most four, we prove that explicit SSP TSRK methods have order at most eight. We present explicit TSRK methods of up to eighth order that were found by numerical search. These methods have larger SSP coefficients than any known methods of the same order of accuracy and may be implemented in a form with relatively modest storage requirements. The usefulness of the TSRK methods is demonstrated through numerical examples, including integration of very high order weighted essentially non-oscillatory discretizations.
Two-step Raman spectroscopy method for tumor diagnosis
Zakharov, V. P.; Bratchenko, I. A.; Kozlov, S. V.; Moryatov, A. A.; Myakinin, O. O.; Artemyev, D. N.
2014-05-01
Two-step Raman spectroscopy phase method was proposed for differential diagnosis of malignant tumor in skin and lung tissue. It includes detection of malignant tumor in healthy tissue on first step with identification of concrete cancer type on the second step. Proposed phase method analyze spectral intensity alteration in 1300-1340 and 1640-1680 cm-1 Raman bands in relation to the intensity of the 1450 cm-1 band on first step, and relative differences between RS intensities for tumor area and healthy skin closely adjacent to the lesion on the second step. It was tested more than 40 ex vivo samples of lung tissue and more than 50 in vivo skin tumors. Linear Discriminant Analysis, Quadratic Discriminant Analysis and Support Vector Machine were used for tumors type classification on phase planes. It is shown that two-step phase method allows to reach 88.9% sensitivity and 87.8% specificity for malignant melanoma diagnosis (skin cancer); 100% sensitivity and 81.5% specificity for adenocarcinoma diagnosis (lung cancer); 90.9% sensitivity and 77.8% specificity for squamous cell carcinoma diagnosis (lung cancer).
Multi-time-step domain coupling method with energy control
DEFF Research Database (Denmark)
Mahjoubi, N.; Krenk, Steen
2010-01-01
A multi-time-step integration method is proposed for solving structural dynamics problems on multiple domains. The method generalizes earlier state-space integration algorithms by introducing displacement constraints via Lagrange multipliers, representing the time-integrated constraint forces over...
Mixed time integration methods for transient thermal analysis of structures
Liu, W. K.
1983-01-01
The computational methods used to predict and optimize the thermal-structural behavior of aerospace vehicle structures are reviewed. In general, two classes of algorithms, implicit and explicit, are used in transient thermal analysis of structures. Each of these two methods has its own merits. Due to the different time scales of the mechanical and thermal responses, the selection of a time integration method can be a difficult yet critical factor in the efficient solution of such problems. Therefore mixed time integration methods for transient thermal analysis of structures are being developed. The computer implementation aspects and numerical evaluation of these mixed time implicit-explicit algorithms in thermal analysis of structures are presented. A computationally-useful method of estimating the critical time step for linear quadrilateral element is also given. Numerical tests confirm the stability criterion and accuracy characteristics of the methods. The superiority of these mixed time methods to the fully implicit method or the fully explicit method is also demonstrated.
Apparatus and method for thermal power generation
Cohen, Paul; Redding, Arnold H.
1978-01-01
An improved thermal power plant and method of power generation which minimizes thermal stress and chemical impurity buildup in the vaporizing component, particularly beneficial under loss of normal feed fluid and startup conditions. The invention is particularly applicable to a liquid metal fast breeder reactor plant.
Plante, Ianik; Devroye, Luc
2017-10-01
Ionizing radiation interacts with the water molecules of the tissues mostly by ionizations and excitations, which result in the formation of the radiation track structure and the creation of radiolytic species such as H.,.OH, H2, H2O2, and e-aq. After their creation, these species diffuse and may chemically react with the neighboring species and with the molecules of the medium. Therefore radiation chemistry is of great importance in radiation biology. As the chemical species are not distributed homogeneously, the use of conventional models of homogeneous reactions cannot completely describe the reaction kinetics of the particles. Actually, many simulations of radiation chemistry are done using the Independent Reaction Time (IRT) method, which is a very fast technique to calculate radiochemical yields but which do not calculate the positions of the radiolytic species as a function of time. Step-by-step (SBS) methods, which are able to provide such information, have been used only sparsely because these are time-consuming in terms of calculation. Recent improvements in computer performance now allow the regular use of the SBS method in radiation chemistry. The SBS and IRT methods are both based on the Green's functions of the diffusion equation (GFDE). In this paper, several sampling algorithms of the GFDE and for the IRT method are presented. We show that the IRT and SBS methods are exactly equivalent for 2-particles systems for diffusion and partially diffusion-controlled reactions between non-interacting particles. We also show that the results obtained with the SBS simulation method with periodic boundary conditions are in agreement with the predictions by classical reaction kinetics theory, which is an important step towards using this method for modelling of biochemical networks and metabolic pathways involved in oxidative stress. Finally, the first simulation results obtained with the code RITRACKS (Relativistic Ion Tracks) are presented.
Composite-step product methods for solving nonsymmetric linear systems
Energy Technology Data Exchange (ETDEWEB)
Chan, T.F.; Szeto, T. [Univ. of California, Los Angeles, CA (United States)
1994-12-31
The Biconjugate Gradient (BCG) algorithm is the {open_quotes}natural{close_quotes} generalization of the classical Conjugate Gradient method to nonsymmetric linear systems. It is an attractive method because of its simplicity and its good convergence properties. Unfortunately, BCG suffers from two kinds of breakdowns (divisions by 0): one due to the non-existence of the residual polynomial, and the other due to a breakdown in the recurrence relationship used. There are many look-ahead techniques in existence which are designed to handle these breakdowns. Although the step size needed to overcome an exact breakdown can be computed in principle, these methods can unfortunately be quite complicated for handling near breakdowns since the sizes of the look-ahead steps are variable (indeed, the breakdowns can be incurable). Recently, Bank and Chan introduced the Composite Step Biconjugate Gradient (CSBCG) algorithm, an alternative which cures only the first of the two breakdowns mentioned by skipping over steps for which the BCG iterate is not defined. This is done with a simple modification of BCG which needs only a maximum look-ahead step size of 2 to eliminate the (near) breakdown and to smooth the sometimes erratic convergence of BCG. Thus, instead of a more complicated (but less prone to breakdown) version, CSBCG cures only one kind of breakdown, but does so with a minimal modification to the usual implementation of BCG in the hope that its empirically observed stability will be inherited. The authors note, then, that the Composite Step idea can be incorporated anywhere the BCG polynomial is used; in particular, in product methods such as CGS, Bi-CGSTAB, and TFQMR. Doing this not only cures the breakdown mentioned above, but also takes on the advantages of these product methods, namely, no multiplications by the transpose matrix and a faster convergence rate than BCG.
A Global Step Planning Method for Biped Robot Considering Obstacles
Tsuji, Toshiaki; Ohnishi, Kouhei
This paper discusses about step planning of a biped robot in an environment with obstacles. Biped robot has a mechanical advantage to work in human surroundings. This is accomplished by its capability to select the discrete contact point with the ground. Though its foot placement should be discussed to step over obstacles, it is difficult because dynamic biped locomotion is a complex interaction system between upper body motion and stepping point. Applying the idea of virtual supporting point, this complex interaction is solved. The collision detection is easily achieved through modeling the obstacles to an off-limits on the horizontal plane. A stamp area is set in order to avoid the extreme stride alteration. Through these methods, the robot can prepare for the obstacle beforehand and select a series of footsteps that provides stable locomotion. Experimental results are shown to confirm the validity of the proposed methods.
Nonlinear stability and time step selection for the MPM method
Berzins, Martin
2018-01-01
The Material Point Method (MPM) has been developed from the Particle in Cell (PIC) method over the last 25 years and has proved its worth in solving many challenging problems involving large deformations. Nevertheless there are many open questions regarding the theoretical properties of MPM. For example in while Fourier methods, as applied to PIC may provide useful insight, the non-linear nature of MPM makes it necessary to use a full non-linear stability analysis to determine a stable time step for MPM. In order to begin to address this the stability analysis of Spigler and Vianello is adapted to MPM and used to derive a stable time step bound for a model problem. This bound is contrasted against traditional Speed of sound and CFL bounds and shown to be a realistic stability bound for a model problem.
A Transfer Voltage Simulation Method for Generator Step Up Transformers
Funabashi, Toshihisa; Sugimoto, Toshirou; Ueda, Toshiaki; Ametani, Akihiro
It has been found from measurements for 13 sets of GSU transformers that a transfer voltage of a generator step-up (GSU) transformer involves one dominant oscillation frequency. The frequency can be estimated from the inductance and capacitance values of the GSU transformer low-voltage-side. This observation has led to a new method for simulating a GSU transformer transfer voltage. The method is based on the EMTP TRANSFORMER model, but stray capacitances are added. The leakage inductance and the magnetizing resistance are modified using approximate curves for their frequency characteristics determined from the measured results. The new method is validated in comparison with the measured results.
A two-step method for developing a control rod program for boiling water reactors
International Nuclear Information System (INIS)
Taner, M.S.; Levine, S.H.; Hsiao, M.Y.
1992-01-01
This paper reports on a two-step method that is established for the generation of a long-term control rod program for boiling water reactors (BWRs). The new method assumes a time-variant target power distribution in core depletion. In the new method, the BWR control rod programming is divided into two steps. In step 1, a sequence of optimal, exposure-dependent Haling power distribution profiles is generated, utilizing the spectral shift concept. In step 2, a set of exposure-dependent control rod patterns is developed by using the Haling profiles generated at step 1 as a target. The new method is implemented in a computer program named OCTOPUS. The optimization procedure of OCTOPUS is based on the method of approximation programming, in which the SIMULATE-E code is used to determine the nucleonics characteristics of the reactor core state. In a test in cycle length over a time-invariant, target Haling power distribution case because of a moderate application of spectral shift. No thermal limits of the core were violated. The gain in cycle length could be increased further by broadening the extent of the spetral shift
Huang, Shengzhou; Li, Mujun; Shen, Lianguan; Qiu, Jinfeng; Zhou, Youquan
2017-06-01
A flexible fabrication method for the biomimetic compound eye (BCE) array is proposed. In this method, a triple-layer sandwich-like coating configuration was introduced, and the required hierarchic microstructures are formed with a simple single-scan exposure in maskless digital lithography. Taking advantage of the difference of glass transition point (Tg) between photoresists of each layer, the pre-formed hierarchic microstructures are in turn reflowed to the curved substrate and the BCE ommatidia in a two-step thermal reflow process. To avoid affecting the spherical substrate formed in the first thermal reflow, a non-contact strategy was proposed in the second reflow process. The measurement results were in good agreement with the designed BCE profiles. Results also showed that the fabricated BCE had good performances in optical test. The presented method is flexible, convenient, low-cost and can easily adapt to the fabrications of other optical elements with hierarchic microstructures.
Advanced Testing Method for Ground Thermal Conductivity
Energy Technology Data Exchange (ETDEWEB)
Liu, Xiaobing [ORNL; Clemenzi, Rick [Geothermal Design Center Inc.; Liu, Su [University of Tennessee (UT)
2017-04-01
A new method is developed that can quickly and more accurately determine the effective ground thermal conductivity (GTC) based on thermal response test (TRT) results. Ground thermal conductivity is an important parameter for sizing ground heat exchangers (GHEXs) used by geothermal heat pump systems. The conventional GTC test method usually requires a TRT for 48 hours with a very stable electric power supply throughout the entire test. In contrast, the new method reduces the required test time by 40%–60% or more, and it can determine GTC even with an unstable or intermittent power supply. Consequently, it can significantly reduce the cost of GTC testing and increase its use, which will enable optimal design of geothermal heat pump systems. Further, this new method provides more information about the thermal properties of the GHEX and the ground than previous techniques. It can verify the installation quality of GHEXs and has the potential, if developed, to characterize the heterogeneous thermal properties of the ground formation surrounding the GHEXs.
Sakurai, Takayoshi; Kusano, Takashi; Saito, Yutaka; Hirato, Kota; Kato, Masakazu; Murai, Masahiko; Nagata, Junichi
This paper presents an effective and practical method based on the Lagrangian relaxation method for solving hydro-thermal unit commitment problem in which operational constraints involve spinning reserve requirements for thermal units and prohibition of simultaneous unit start-up/shut-down at the same plant. This method is processed in each iteration step of LRM that enables a direct solution. To improve convergence, this method applies an augmented Lagrangian relaxation method. Its effectiveness demonstrated for a real power system.
In-step Two-phase Flow (TPF) Thermal Control Experiment
1992-01-01
The Two-Phase Flow Thermal Control Experiment is part of the NASA/OAST In-Space Technology Experiments (In-STEP) Program. The experiment is configured for the Hitchhiker Shuttle payload system and consists of a capillary pumped loop, heatpipe radiator, and two-phase flow heat exchanger. The flight experiment design approach, test plan, payload design, and test components are described in outline and graphic form.
On-Orbit Thermal Design and Validation of 1 U Standardized CubeSat of STEP Cube Lab
Directory of Open Access Journals (Sweden)
Soo-Jin Kang
2016-01-01
Full Text Available The Cube Laboratory for Space Technology Experimental Projects (STEP Cube Lab is a cube satellite (CubeSat classified as a pico-class satellite of 1 U (unit size. Its main mission objective is to exploit core space technologies researched by domestic universities and verify the effectiveness of these technologies through on-orbit tests using the CubeSat. To guarantee a successful mission under extreme space thermal environments, proper thermal design is important. This paper describes the development process undertaken in the thermal design of the STEP Cube Lab, based on a passive approach, and its validation test. The system functionality and thermal design were verified through thermal vacuum and thermal balance tests under space simulated thermal vacuum environment condition. Finally, the orbital temperature of each component was predicted using a highly reliable correlated thermal mathematical model of the CubeSat obtained from the thermal balance test.
Nanoscale thermal transport: Theoretical method and application
Zeng, Yu-Jia; Liu, Yue-Yang; Zhou, Wu-Xing; Chen, Ke-Qiu
2018-03-01
With the size reduction of nanoscale electronic devices, the heat generated by the unit area in integrated circuits will be increasing exponentially, and consequently the thermal management in these devices is a very important issue. In addition, the heat generated by the electronic devices mostly diffuses to the air in the form of waste heat, which makes the thermoelectric energy conversion also an important issue for nowadays. In recent years, the thermal transport properties in nanoscale systems have attracted increasing attention in both experiments and theoretical calculations. In this review, we will discuss various theoretical simulation methods for investigating thermal transport properties and take a glance at several interesting thermal transport phenomena in nanoscale systems. Our emphasizes will lie on the advantage and limitation of calculational method, and the application of nanoscale thermal transport and thermoelectric property. Project supported by the Nation Key Research and Development Program of China (Grant No. 2017YFB0701602) and the National Natural Science Foundation of China (Grant No. 11674092).
Caraveo Frescas, Jesus Alfonso
2015-05-28
Embodiments of the present disclosure include nanowire field-effect transistors, systems for temperature history detection, methods for thermal history detection, a matrix of field effect transistors, and the like.
Calorimetry and thermal methods in catalysis
Auroux, Aline
2013-01-01
The book is about calorimetry and thermal analysis methods, alone or linked to other techniques, as applied to the characterization of catalysts, supports and adsorbents, and to the study of catalytic reactions in various domains: air and wastewater treatment, clean and renewable energies, refining of hydrocarbons, green chemistry, hydrogen production and storage. The book is intended to fill the gap between the basic thermodynamic and kinetics concepts acquired byÂ students during their academic formation, and the use of experimental techniques such as thermal analysis and calorimetry to answ
Energy Technology Data Exchange (ETDEWEB)
Takashiri, Masayuki, E-mail: takashiri@tokai-u.jp; Kurita, Kensuke [Department of Materials Science, Tokai University, 4-1-1 Kitakaname, Hiratsuka, Kanagawa 259-1292 (Japan); Hagino, Harutoshi; Miyazaki, Koji [Department of Mechanical and Control Engineering, Kyushu Institute of Technology, 1-1 Sensui, Tobata-ku, Kitakyushu 804-8550 (Japan); Tanaka, Saburo [Department of Mechanical Engineering, College of Engineering, Nihon University, 1 Nakagawara, Tokusada, Tamuramachi, Koriyama, Fukushima 963-8642 (Japan)
2015-08-14
A two-step method that combines homogeneous electron beam (EB) irradiation and thermal annealing has been developed to enhance the thermoelectric properties of nanocrystalline bismuth selenium telluride thin films. The thin films, prepared using a flash evaporation method, were treated with EB irradiation in a N{sub 2} atmosphere at room temperature and an acceleration voltage of 0.17 MeV. Thermal annealing was performed under Ar/H{sub 2} (5%) at 300 °C for 60 min. X-ray diffraction was used to determine that compositional phase separation between bismuth telluride and bismuth selenium telluride developed in the thin films exposed to higher EB doses and thermal annealing. We propose that the phase separation was induced by fluctuations in the distribution of selenium atoms after EB irradiation, followed by the migration of selenium atoms to more stable sites during thermal annealing. As a result, thin film crystallinity improved and mobility was significantly enhanced. This indicates that the phase separation resulting from the two-step method enhanced, rather than disturbed, the electron transport. Both the electrical conductivity and the Seebeck coefficient were improved following the two-step method. Consequently, the power factor of thin films that underwent the two-step method was enhanced to 20 times (from 0.96 to 21.0 μW/(cm K{sup 2}) that of the thin films treated with EB irradiation alone.
Botts, Jonathan; Savioja, Lauri
2015-04-01
For time-domain modeling based on the acoustic wave equation, spectral methods have recently demonstrated promise. This letter presents an extension of a spectral domain decomposition approach, previously used to solve the lossless linear wave equation, which accommodates frequency-dependent atmospheric attenuation and assignment of arbitrary dispersion relations. Frequency-dependence is straightforward to assign when time-stepping is done in the spectral domain, so combined losses from molecular relaxation, thermal conductivity, and viscosity can be approximated with little extra computation or storage. A mode update free from numerical dispersion is derived, and the model is confirmed with a numerical experiment.
Thermal-Force Deformation of a Physically Nonlinear Three-Layer Stepped Rod
Starovoitov, É. I.; Leonenko, D. V.; Tarlakovskii, D. V.
2016-11-01
Consideration has been given to the thermal-force deformation of a three-layer plastoelastic rod with a stepped thickness of one supporting layer. The physical equations of state are consistent with the Il'yushin theory of small plastoelastic deformations. To describe the kinematics of a rod bundle nonsymmetric across the thickness, the authors adopted the broken-normal hypotheses. A system of equilibrium equations has been derived, and its general iterative solution in displacements has been obtained. A numerical parametric analysis of the rod's stress-strain state has been made.
One-step method for the production of nanofluids
Energy Technology Data Exchange (ETDEWEB)
Kostic, Milivoje [Chicago, IL; Golubovic, Mihajlo [Chicago, IL; Hull, John R [Downers Grove, IL; Choi, Stephen U. S. [Napersville, IL
2010-05-18
A one step method and system for producing nanofluids by a particle-source evaporation and deposition of the evaporant into a base fluid. The base fluid such (i.e. ethylene glycol) is placed in a rotating cylindrical drum having an adjustable heater-boat-evaporator and heat exchanger-cooler apparatus. As the drum rotates, a thin liquid layer is formed on the inside surface of the drum. A heater-boat-evaporator having an evaporant material (particle-source) placed within its boat evaporator is adjustably positioned near a portion of the rotating thin liquid layer, the evaporant material being heated thereby evaporating a portion of the evaporant material, the evaporated material absorbed by the liquid film to form nanofluid.
One-step method for the production of nanofluids
Kostic, Milivoje [Sycamore, IL; Golubovic, Mihajlo [Chicago, IL; Hull, John [Downers Grove, IL; Choi, Stephen U. S. [Naperville, IL
2011-08-16
A one step method and system for producing nanofluids by a nanoparticle-source evaporation and deposition of the evaporant into a base fluid. The base fluid such oil or ethylene glycol is placed in a rotating cylindrical drum having an adjustable heater-boat-evaporator and heat exchanger-cooler apparatus. As the drum rotates, a thin liquid layer is formed on the inside surface of the drum. An insulated heater-boat-evaporator having an evaporant material (nanoparticle-source) placed within its boat evaporator is adjustably positioned near a portion of the rotating thin liquid layer, the evaporant material being heated thereby evaporating a portion of the evaporant material and forming nanoparticles, the nanoparticles absorbed by the liquid film to form nanofluid.
Analysis of the step responses of laminar premixed flames to forcing by non-thermal plasma
Lacoste, Deanna A.
2016-07-16
The step responses of lean methane-air flames to non-thermal plasma forcing is reported. The experimental setup consists of an axisymmetric burner, with a nozzle made of a quartz tube. The equivalence ratio is 0.95, allowing stabilization of the flame in a V-shape or an M-shape geometry, over a central stainless steel rod. The plasma is produced by short pulses of 10-ns duration, 8-kV maximum voltage amplitude, applied at 10 kHz. The central rod is used as a cathode, while the anode is a stainless steel ring, fixed on the outer surface of the quartz tube. Plasma forcing is produced by positive or negative steps of plasma. The step response of the flame is investigated through heat release rate (HRR) fluctuations, to facilitate comparisons with flame response to acoustic perturbations. The chemiluminescence of CH* between two consecutive pulses was recorded using an intensified camera equipped with an optical filter to estimate the HRR fluctuations. First, the results show that the flame does not respond to each single plasma pulse, but is affected only by the average plasma power, confirming the step nature of the forcing. The temporal evolutions of HRR are analyzed and the flame transfer functions are determined. A forcing mechanism, as a local increase in the reactivity of the fluid close to the rod, is proposed and compared with numerical simulations. Experiments and numerical simulations are in good qualitative agreement. © 2016.
Lin, Guoping; Candela, Y; Tillement, O; Cai, Zhiping; Lefèvre-Seguin, V; Hare, J
2012-12-15
A method based on thermal bistability for ultralow-threshold microlaser optimization is demonstrated. When sweeping the pump laser frequency across a pump resonance, the dynamic thermal bistability slows down the power variation. The resulting line shape modification enables a real-time monitoring of the laser characteristic. We demonstrate this method for a functionalized microsphere exhibiting a submicrowatt laser threshold. This approach is confirmed by comparing the results with a step-by-step recording in quasi-static thermal conditions.
Jing,Lei; Cheng, Zixue; Wang, Junbo; Zhou, Yinghui
2011-01-01
Embedded system technologies are undergoing dramatic change. Competent embedded system engineers are becoming a scarce resource in the industry. Given this, universities should revise their specialist education to meet industry demands. In this paper, a spirally tight-coupled step-by-step educational method, based on an analysis of industry…
Applied mathematical methods in nuclear thermal hydraulics
International Nuclear Information System (INIS)
Ransom, V.H.; Trapp, J.A.
1983-01-01
Applied mathematical methods are used extensively in modeling of nuclear reactor thermal-hydraulic behavior. This application has required significant extension to the state-of-the-art. The problems encountered in modeling of two-phase fluid transients and the development of associated numerical solution methods are reviewed and quantified using results from a numerical study of an analogous linear system of differential equations. In particular, some possible approaches for formulating a well-posed numerical problem for an ill-posed differential model are investigated and discussed. The need for closer attention to numerical fidelity is indicated
Influence of the drying method in chitosans purification step
International Nuclear Information System (INIS)
Fonseca, Ana C.M.; Batista, Jorge G.S.; Bettega, Antonio; Lima, Nelson B. de
2015-01-01
Currently, the study of extracellular biopolymers properties has received prominence for being easy extraction and purification. Chitosan has been an attractive proposition for applications in various fields such as engineering, biotechnology, medicine and pharmacology. For such applications, it is necessary purification of chitosan to obtain a product more concentrated and free of undesirable impurities. However, at this stage of the process of obtaining the biopolymer may occur morphological and physicochemical changes. This study evaluated the influence of the drying process after purification of a commercial chitosan sample and the importance of this step and its cost/benefit in applications requiring a high degree of purity. The method of drying influenced in the organoleptic properties and in the main characteristics of material. Analysis of the crystal structure by X-ray diffraction showed that the degree of crystallinity, X (%), in the purified chitosan samples was lower when compared with the unpurified sample. The degree of acetylation, DA (%), was analyzed by spectroscopy infrared with no significant changes on the three drying methods assessed, unlike the viscosimetric molecular weight, M v , determined by capillary viscometry. (author)
Thermal energy storage devices, systems, and thermal energy storage device monitoring methods
Tugurlan, Maria; Tuffner, Francis K; Chassin, David P.
2016-09-13
Thermal energy storage devices, systems, and thermal energy storage device monitoring methods are described. According to one aspect, a thermal energy storage device includes a reservoir configured to hold a thermal energy storage medium, a temperature control system configured to adjust a temperature of the thermal energy storage medium, and a state observation system configured to provide information regarding an energy state of the thermal energy storage device at a plurality of different moments in time.
The two-step vacuum-microwave method for histoprocessing
Boon, ME; WalsPaap, CH; Visinoni, FA; Kok, LP
1995-01-01
When microwaving and vacuum is combined, decrease of boiling temperature can be exploited in the histoprocessing procedures allowing a completely novel approach for impregnating tissue with paraffin. We found that, if the pressure is sufficiently low in the paraffin step, no ethyl-alcohol step is
A comparison of thermal zone aggregation methods
Energy Technology Data Exchange (ETDEWEB)
Dobbs, Justin R. [Cornell University; Hencey, Brandon M. [Cornell University
2012-12-10
The impact of increasing energy prices on building operation budgets has fueled demand for more energy-efficient structures. Existing building energy simulation tools generate an immense amount of data yet comparatively little knowledge. This paper introduces a framework that allows aggregation-based model reduction to operate on geometric building information models. The resulting aggregation sequence provides designers with faster simulations and affords insight into complex multi-scale thermal interactions. A comparison of the trade-off between simulation speed and accuracy for three hierarchical cluster partitioning methods concludes the discussion.
Analysis of thermal power calibration method
International Nuclear Information System (INIS)
Zagar, T.; Ravnik, M.; Persic, A.
2000-01-01
The methods for determining fuel element burnup have recently become interesting because of activities related to the shipment of highly enriched fuel elements back to the United States for final disposal before 2009. The most common and practical method for determining fuel element burnup in research reactors is reactor calculation. Experience has shown that burnup calculations become complicated and biased with uncertainties if a long period of reactor operation must be reproduced. Besides this, accuracy of calculated burnup is always limited with accuracy of reactor power calibration, since burnup calculation is based on calculated power density distribution, which is usually expressed in terms of power released per fuel element and normalised to the reactor power It is obvious that reactor thermal power calibration is very important for precise fuel element burnup calculation. Calculated fuel element burnup is linearly dependent on the thermal reactor power. The reactor power level may be determined from measured absolute thermal flux distribution across the core in the horizontal and vertical planes. Flux distributions are measured with activation of cadmium covered and bare foils irradiated by the steady reactor power. But it should be realised that this method is time consuming and not accurate. This method is practical only for zero power reactors and is in practice very seldom performed for other reactors (e.g. for TRIGA reactor in Ljubljana absolute thermal flux distribution was not performed since reactor reconstruction in 1991). In case of power reactors and research reactors in which a temperature rise across the core is produced and measured than a heat balance method is the most common and accurate method of determining the power output of the core. The purpose of this paper is to analyse the accuracy of calorimetric reactor power calibration method and to analyse the influence of control rod position on nuclear detector reading for TRIGA reactors
Computational Experiments on the Step and Frequency Responses of a Three-Axis Thermal Accelerometer
Directory of Open Access Journals (Sweden)
Yoshifumi Ogami
2017-11-01
Full Text Available The sensor response has been reported to become highly nonlinear when the acceleration added to a thermal accelerator is very large, so the same response can be observed for two accelerations with different magnitudes and opposite signs. Some papers have reported the frequency response for the horizontal acceleration to be a first-order system, while others have reported it to be a second-order system. The response for the vertical acceleration has not been studied. In this study, computational experiments were performed to examine the step and frequency responses of a three-axis thermal accelerometer. The results showed that monitoring the temperatures at two positions and making use of cross-axis sensitivity allow a unique acceleration to be determined even when the range of the vertical acceleration is very large (e.g., −10,000–10,000 g. The frequency response was proven to be a second-order system for horizontal acceleration and a third-order system for vertical acceleration.
Sheng, Xiao-Qi; Wang, Yi-Chao
2017-05-01
The aim of the present study was to conduct preliminary clinical screening and monitoring using a novel two-step derivatization process of urine in five categories of inherited metabolic disease (IMD). Urine samples (100 µl, containing 2.5 mmol/l creatinine) were taken from patients with IMDs. The collected urine was then treated using a two-step derivatization method (with oximation and silylation at room temperature), where urea and protein were removed. In the first step of the derivatization, α-ketoacids and α-aldehyde acids were prepared by oximation using novel oximation reagents. The second-step of the derivatization was that residues were silylated for analysis. Urine samples were examined using gas chromatography/mass spectrometry (GC/MS) and a retention time-locking technique. The simultaneous analysis and identification of >400 metabolites in >130 types of IMD was possible from the GC/MS results, where the IMDs included phenylketonuria, ornithine transcarbamylase deficiency, neonatal intrahepatic cholestasis caused by citrin deficiency, β-ureidopropionase deficiency and mitochondrial metabolic disorders. This method was demonstrated to have good repeatability. Considering α-ketoglutarate (α-KG) as an example, the relative standard deviations (RSDs) of the α-KG retention time and peak area were 0.8 and 3.9%, respectively, the blank spiked recovery rate was between 89.6 and 99.8%, and the RSD was ≤7.5% (n=5). The method facilitates the analysis of thermally non-stable and semi-volatile metabolites in urine, and greatly expands the range of materials that can be synchronously screened by GC/MS. Furthermore, it provides a comprehensive, effective and reliable biochemical analysis platform for the pathological research of IMDs.
DEFF Research Database (Denmark)
Rasmussen, Christian Jørgen
2001-01-01
Presents a simple and fast method for determination of the step size that exactly leads to a prescribed accuracy when signal propagation through nonlinear optical fibres is computed using the split-step Fourier method.......Presents a simple and fast method for determination of the step size that exactly leads to a prescribed accuracy when signal propagation through nonlinear optical fibres is computed using the split-step Fourier method....
Du, Xiuyuan; Li, Baizhan; Liu, Hong; Yang, Dong; Yu, Wei; Liao, Jianke; Huang, Zhichao; Xia, Kechao
2014-01-01
This paper reports on studies of the effect of temperature step-change (between a cool and a neutral environment) on human thermal sensation and skin temperature. Experiments with three temperature conditions were carried out in a climate chamber during the period in winter. Twelve subjects participated in the experiments simulating moving inside and outside of rooms or cabins with air conditioning. Skin temperatures and thermal sensation were recorded. Results showed overshoot and asymmetry of TSV due to the step-change. Skin temperature changed immediately when subjects entered a new environment. When moving into a neutral environment from cool, dynamic thermal sensation was in the thermal comfort zone and overshoot was not obvious. Air-conditioning in a transitional area should be considered to limit temperature difference to not more than 5°C to decrease the unacceptability of temperature step-change. The linear relationship between thermal sensation and skin temperature or gradient of skin temperature does not apply in a step-change environment. There is a significant linear correlation between TSV and Qloss in the transient environment. Heat loss from the human skin surface can be used to predict dynamic thermal sensation instead of the heat transfer of the whole human body. PMID:25136808
Directory of Open Access Journals (Sweden)
Xiuyuan Du
Full Text Available This paper reports on studies of the effect of temperature step-change (between a cool and a neutral environment on human thermal sensation and skin temperature. Experiments with three temperature conditions were carried out in a climate chamber during the period in winter. Twelve subjects participated in the experiments simulating moving inside and outside of rooms or cabins with air conditioning. Skin temperatures and thermal sensation were recorded. Results showed overshoot and asymmetry of TSV due to the step-change. Skin temperature changed immediately when subjects entered a new environment. When moving into a neutral environment from cool, dynamic thermal sensation was in the thermal comfort zone and overshoot was not obvious. Air-conditioning in a transitional area should be considered to limit temperature difference to not more than 5°C to decrease the unacceptability of temperature step-change. The linear relationship between thermal sensation and skin temperature or gradient of skin temperature does not apply in a step-change environment. There is a significant linear correlation between TSV and Qloss in the transient environment. Heat loss from the human skin surface can be used to predict dynamic thermal sensation instead of the heat transfer of the whole human body.
Compact Ag@Fe3O4 Core-shell Nanoparticles by Means of Single-step Thermal Decomposition Reaction
Brollo, Maria Eugênia F.; López-Ruiz, Román; Muraca, Diego; Figueroa, Santiago J. A.; Pirota, Kleber R.; Knobel, Marcelo
2014-10-01
A temperature pause introduced in a simple single-step thermal decomposition of iron, with the presence of silver seeds formed in the same reaction mixture, gives rise to novel compact heterostructures: brick-like Ag@Fe3O4 core-shell nanoparticles. This novel method is relatively easy to implement, and could contribute to overcome the challenge of obtaining a multifunctional heteroparticle in which a noble metal is surrounded by magnetite. Structural analyses of the samples show 4 nm silver nanoparticles wrapped within compact cubic external structures of Fe oxide, with curious rectangular shape. The magnetic properties indicate a near superparamagnetic like behavior with a weak hysteresis at room temperature. The value of the anisotropy involved makes these particles candidates to potential applications in nanomedicine.
Strong Stability Preserving Explicit Linear Multistep Methods with Variable Step Size
Hadjimichael, Yiannis
2016-09-08
Strong stability preserving (SSP) methods are designed primarily for time integration of nonlinear hyperbolic PDEs, for which the permissible SSP step size varies from one step to the next. We develop the first SSP linear multistep methods (of order two and three) with variable step size, and prove their optimality, stability, and convergence. The choice of step size for multistep SSP methods is an interesting problem because the allowable step size depends on the SSP coefficient, which in turn depends on the chosen step sizes. The description of the methods includes an optimal step-size strategy. We prove sharp upper bounds on the allowable step size for explicit SSP linear multistep methods and show the existence of methods with arbitrarily high order of accuracy. The effectiveness of the methods is demonstrated through numerical examples.
Solar thermal production of zinc - Final steps toward scale-up - Final report
Energy Technology Data Exchange (ETDEWEB)
Meier, A.
2008-05-15
A 10 kW receiver-reactor prototype (called ZIRRUS) was further improved and tested for the solar thermal de-composition of ZnO, which is the 1{sup st} step of the two-step water-splitting thermochemical ZnO/Zn cycle. The rotating cylindrical cavity was made of either sintered ZnO or sintered Al{sub 2}O{sub 3} tiles placed on top of a multi-layer Al{sub 2}O{sub 3}-SiO{sub 2}-Y{sub 2}O{sub 3}-based ceramics for thermal shock resistance, mechanical stability, gas diffusion barrier, and thermal insulation. Pre-heated Ar gas was injected for aerodynamic window protection and for minimizing recombination of product gases in the cavity. Experimentation was carried out at PSI's High-Flux Solar Simulator with the direct heating 10 kW reactor prototype subjected to peak radiative fluxes exceeding 5,800 suns. The reactor operated without incident for a total of more than 40 h at maximum temperatures - measured behind the ZnO and Al{sub 2}O{sub 3} tiles - ranging from 1807-1907 K. Thermal dissociation of ZnO(s) near 2000 K was demonstrated for experimental runs over 4 h in transient ablation mode with up to nine semi-continuous feed cycles of ZnO particles. A working Zn/O{sub 2} separation device based on the rapid quenching of the Zn/O{sub 2} mixture is ready to be incorporated at the exit of the solar reactor. Zinc yields of up to 94% were obtained when using total Ar/Zn(g) dilution of 530 and a cooling rate of about 10{sup 5} K/s. The fully integrated solar reactor will be scaled up to the pilot scale of 100 kW. A newly developed reactor model that couples radiation, conduction, and convection heat transfer to the reaction kinetics will allow determining optimal operational conditions for matching the feeding rate to the reaction rate and for maximizing solar-to-chemical energy conversion efficiency. The 2{sup nd} step of the ZnO/Zn cycle has been experimentally demonstrated at ETH using an aerosol-flow reactor for in-situ formation and hydrolysis of Zn nanoparticles
Thermal Testing Methods for Solar Dryers
DEFF Research Database (Denmark)
Singh, Shobhana
2017-01-01
of the dryer system. Since commercial growth and acceptance of any solar dryer system momentously depend on its performance guarantee, the development of a standard methodology for their thermal testing has become necessary. The standard testing method not only provides better performance management......Solar food drying is a complex heat and mass transfer phenomena which depend on a number of drying process-dependent parameters such as operating conditions and characteristics of the food product to be dried. The variation in these parameters significantly affects the overall performance...... of the dryer system but allows the manufacturers to achieve competitive efficiency and good product quality by comparing the available designs. In this chapter, an extensive review of solar dryer performance evaluation has been carried out. Furthermore, the chapter describes the existing testing procedures...
On-Orbit Thermal Design and Validation of 1 U Standardized CubeSat of STEP Cube Lab
Kang, Soo-Jin; Oh, Hyun-Ung
2016-01-01
The Cube Laboratory for Space Technology Experimental Projects (STEP Cube Lab) is a cube satellite (CubeSat) classified as a pico-class satellite of 1 U (unit) size. Its main mission objective is to exploit core space technologies researched by domestic universities and verify the effectiveness of these technologies through on-orbit tests using the CubeSat. To guarantee a successful mission under extreme space thermal environments, proper thermal design is important. This paper describes the ...
Combining building thermal simulation methods and LCA methods
DEFF Research Database (Denmark)
Pedersen, Frank; Hansen, Klaus; Wittchen, Kim Bjarne
2008-01-01
Thsi paper describes recent efforts made by the Danish Building Research Institute regarding the integration of a life cycle assessment (LCA) method into a whole building hygro-thermal simulation tool. The motivation for the work is that the increased requirements to the energy performance...... of buildings (as expressed in EU Directive 2002/91/EC), may in the future be supplemented by requirements to the environmental impact of buildings. This can be seen by the fact that EU recently has given EN mandate to prepare standards for environmental assessment of buildings (CEN/TC 350)....
Cao, Jiliang; Huang, Zhan; Wang, Chaoxia
2018-05-01
Graphene conductive silk substrate is a preferred material because of its biocompatibility, flexibility and comfort. A flexible natural printed silk substrate circuit was fabricated by one step transfer of graphene oxide (GO) paste from transfer paper to the surface of silk fabric and reduction of the GO to reduced graphene oxide (RGO) using a simple hot press treatment. The GO paste was obtained through ultrasonic stirring exfoliation under low temperature, and presented excellent printing rheological properties at high concentration. The silk fabric was obtained a surface electric resistance as low as 12.15 KΩ cm-1, in the concentration of GO 50 g L-1 and hot press at 220 °C for 120 s. Though the whiteness and strength decreased with the increasing of hot press temperature and time slowly, the electric conductivity of RGO surface modification silk substrate improved obviously. The surface electric resistance of RGO/silk fabrics increased from 12.15 KΩ cm-1 to 18.05 KΩ cm-1, 28.54 KΩ cm-1 and 32.53 KΩ cm-1 after 10, 20 and 30 washing cycles, respectively. The results showed that the printed silk substrate circuit has excellent washability. This process requires no chemical reductant, and the reduction efficiency and reduction degree of GO is high. This time-effective and environmentally-friendly one step thermal transfer and reduction graphene oxide onto natural silk substrate method can be easily used to production of reduced graphene oxide (RGO) based flexible printed circuit.
Directory of Open Access Journals (Sweden)
Karina Kwapiszewska
2016-11-01
Full Text Available The paper describes a cheap and accessible technique of a poly(dimethylsiloxane (PDMS master treatment by thermal aging as a step of double casting microfabrication process. Three-dimensional PDMS microstructures could have been achieved using this technique. It was proved, that thermal aging changes nanotopology of a PDMS surface and thus enhances efficiency of double casting prototyping. The thermally aged PDMS master could have been used for multiple and correct replication of over 98% of the fabricated microstructures. Moreover, lack of chemical modification preserved the biocompatibility of PDMS devices. The fabricated microstructures were successfully utilized for 3D cell culture.
Finite element method for incompressible two-fluid model using a fractional step method
International Nuclear Information System (INIS)
Uchiyama, Tomomi
1997-01-01
This paper presents a finite element method for an incompressible two-fluid model. The solution algorithm is based on the fractional step method, which is frequently used in the finite element calculation for single-phase flows. The calculating domain is divided into quadrilateral elements with four nodes. The Galerkin method is applied to derive the finite element equations. Air-water two-phase flows around a square cylinder are calculated by the finite element method. The calculation demonstrates the close relation between the volumetric fraction of the gas-phase and the vortices shed from the cylinder, which is favorably compared with the existing data. It is also confirmed that the present method allows the calculation with less CPU time than the SMAC finite element method proposed in my previous paper. (author)
Bi, Y; Sui, G; Zhou, Q; Heindl, L M; Bock, F; Sun, X; Tang, S; Wang, Z; Cursiefen, C
2013-11-01
To evaluate the efficacy of two-step retrograde closed stenting for treating canalicular laceration. methods: Forty-eight consecutive canalicular laceration cases (48 eyes) were randomised and divided into two groups: a one-step group and a two-step group. In the two-step group (23 cases), the first step was performed in the outpatient department and included identifying the medial cut end of the canaliculus and probing under a slit-lamp microscope, followed by a retrograde canalicular stenting assisted by a memory titanium stylet. The second step was canalicular anastomosis, which was performed in the operating room. In the one-step group (25 cases), all of the surgical procedures were performed when preoperative preparations were simultaneously available. The time elapsed from the doctor visit to the treatment was 4.3 ± 2.4 h in the two-step group and 18.8 ± 6.3 h in the one-step group (Ptwo-step group, and 51.4 ± 24.2 min was needed in the one-step group (Ptwo-step group and 5.4 ± 2.2 in the one-step group (Ptwo-step group and nine cases (36%) in the one-step group required other assisted methods to locate the medial cut end (P=0.007). Twenty-one cases (91.3%) in the two-step group and 20 cases (80%) in the one-step group achieved patent lacrimal drainage systems during a 12-month follow-up (P=0.528). The two-step canalicular anastomosis method allows an early search for the medial cut end of the canaliculus and improves the chances of finding it; it is also a quicker, less invasive method for treating canalicular lacerations.
Three-Step Predictor-Corrector of Exponential Fitting Method for Nonlinear Schroedinger Equations
International Nuclear Information System (INIS)
Tang Chen; Zhang Fang; Yan Haiqing; Luo Tao; Chen Zhanqing
2005-01-01
We develop the three-step explicit and implicit schemes of exponential fitting methods. We use the three-step explicit exponential fitting scheme to predict an approximation, then use the three-step implicit exponential fitting scheme to correct this prediction. This combination is called the three-step predictor-corrector of exponential fitting method. The three-step predictor-corrector of exponential fitting method is applied to numerically compute the coupled nonlinear Schroedinger equation and the nonlinear Schroedinger equation with varying coefficients. The numerical results show that the scheme is highly accurate.
Thermal infrared remote sensing sensors, methods, applications
Kuenzer, Claudia
2013-01-01
This book provides a comprehensive overview of the state of the art in the field of thermal infrared remote sensing. Temperature is one of the most important physical environmental variables monitored by earth observing remote sensing systems. Temperature ranges define the boundaries of habitats on our planet. Thermal hazards endanger our resources and well-being. In this book renowned international experts have contributed chapters on currently available thermal sensors as well as innovative plans for future missions. Further chapters discuss the underlying physics and image processing techni
Blumrich, Matthias A.; Salapura, Valentina
2010-11-02
An apparatus and method are disclosed for single-stepping coherence events in a multiprocessor system under software control in order to monitor the behavior of a memory coherence mechanism. Single-stepping coherence events in a multiprocessor system is made possible by adding one or more step registers. By accessing these step registers, one or more coherence requests are processed by the multiprocessor system. The step registers determine if the snoop unit will operate by proceeding in a normal execution mode, or operate in a single-step mode.
Directory of Open Access Journals (Sweden)
V. S. Niss
2015-01-01
Full Text Available Thermal performance of electronic devices determines the stability and reliability of the equipment. This leads to the need for a detailed thermal analysis of semiconductor devices. The goal of the work is evaluation of thermal parameters of high-power bipolar transistors in plastic packages TO-252 and TO-126 by a method of thermal relaxation differential spectrometry. Thermal constants of device elements and distribution structure of thermal resistance defined as discrete and continuous spectra using previously developed relaxation impedance spectrometer. Continuous spectrum, based on higher-order derivatives of the dynamic thermal impedance, follows the model of Foster, and discrete to model of Cauer. The structure of sample thermal resistance is presented in the form of siх-chain electro-thermal RC model. Analysis of the heat flow spreading in the studied structures is carried out on the basis of the concept of thermal diffusivity. For transistor structures the area and distribution of the heat flow cross-section are determined. On the basis of the measurements the thermal parameters of high-power bipolar transistors is evaluated, in particular, the structure of their thermal resistance. For all of the measured samples is obtained that the thermal resistance of the layer planting crystal makes a defining contribution to the internal thermal resistance of transistors. In the transition layer at the border of semiconductor-solder the thermal resistance increases due to changes in the mechanism of heat transfer. Defects in this area in the form of delamination of solder, voids and cracks lead to additional growth of thermal resistance caused by the reduction of the active square of the transition layer. Method of thermal relaxation differential spectrometry allows effectively control the distribution of heat flow in high-power semiconductor devices, which is important for improving the design, improve the quality of landing crystals of power
Uniform Order Zero- Stable K-Step Block Methods For Initial Value ...
African Journals Online (AJOL)
... successive steps movement at a time (block steps). Numerical examples are given to illustrate the performance of the new procedures. Keywords: Zero stability, Hybrid, k–step, Block methods, first order initial value problem. Journal of the Nigerian Association of Mathematical Physics, Volume 20 (March, 2012), pp 65 – 74 ...
CSIR Research Space (South Africa)
Wilke, DN
2012-07-01
Full Text Available , and is based on a Taylor series expansion using a pure imaginary step. The complex-step method is not subject to subtraction errors as with finite difference approaches when computing first order sensitivities and therefore allows for much smaller step sizes...
MIDPOINT TWO- STEPS RULE FOR THE SQUARE ROOT METHOD
African Journals Online (AJOL)
DR S.E UWAMUSI
Carstensen, C., and Petkovic, M.S., 1994. An Improvement of Gargantini's Simultaneous Inclusion Method for. Polynomial Roots by Scroder's Correction. Applied Numerical Mathematics No. 13, pp 453-458. Carstensen, C., 1991. Linear Construction of Comparison Matrices. Linear Algebra and its Application No 14, pp. 191 ...
MIDPOINT TWO- STEPS RULE FOR THE SQUARE ROOT METHOD
African Journals Online (AJOL)
DR S.E UWAMUSI
predictor and corrector iterations which the algorithm entails do not jump across paths of orientation. ... The paper develops algorithm for the numerical approximation of zeros of polynomial. The proposed method ...... A parallel circular algorithm for the simultaneous determination of all zeros of a complex polynomial ...
Methods and compositions for rapid thermal cycling
Energy Technology Data Exchange (ETDEWEB)
Beer, Neil Reginald; Benett, William J.; Frank, James M.; Deotte, Joshua R.; Spadaccini, Christopher
2018-04-10
The rapid thermal cycling of a material is targeted. A microfluidic heat exchanger with an internal porous medium is coupled to tanks containing cold fluid and hot fluid. Fluid flows alternately from the cold tank and the hot tank into the porous medium, cooling and heating samples contained in the microfluidic heat exchanger's sample wells. A valve may be coupled to the tanks and a pump, and switching the position of the valve may switch the source and direction of fluid flowing through the porous medium. A controller may control the switching of valve positions based on the temperature of the samples and determined temperature thresholds. A sample tray for containing samples to be thermally cycled may be used in conjunction with the thermal cycling system. A surface or internal electrical heater may aid in heating the samples, or may replace the necessity for the hot tank.
Methods and compositions for rapid thermal cycling
Beer, Neil Reginald; Benett, William J.; Frank, James M.; Deotte, Joshua R.; Spadaccini, Christopher
2015-10-27
The rapid thermal cycling of a material is targeted. A microfluidic heat exchanger with an internal porous medium is coupled to tanks containing cold fluid and hot fluid. Fluid flows alternately from the cold tank and the hot tank into the porous medium, cooling and heating samples contained in the microfluidic heat exchanger's sample wells. A valve may be coupled to the tanks and a pump, and switching the position of the valve may switch the source and direction of fluid flowing through the porous medium. A controller may control the switching of valve positions based on the temperature of the samples and determined temperature thresholds. A sample tray for containing samples to be thermally cycled may be used in conjunction with the thermal cycling system. A surface or internal electrical heater may aid in heating the samples, or may replace the necessity for the hot tank.
Thermal energy storage apparatus, controllers and thermal energy storage control methods
Hammerstrom, Donald J.
2016-05-03
Thermal energy storage apparatus, controllers and thermal energy storage control methods are described. According to one aspect, a thermal energy storage apparatus controller includes processing circuitry configured to access first information which is indicative of surpluses and deficiencies of electrical energy upon an electrical power system at a plurality of moments in time, access second information which is indicative of temperature of a thermal energy storage medium at a plurality of moments in time, and use the first and second information to control an amount of electrical energy which is utilized by a heating element to heat the thermal energy storage medium at a plurality of moments in time.
Licht, S
2011-12-15
STEP (solar thermal electrochemical production) theory is derived and experimentally verified for the electrosynthesis of energetic molecules at solar energy efficiency greater than any photovoltaic conversion efficiency. In STEP the efficient formation of metals, fuels, chlorine, and carbon capture is driven by solar thermal heated endothermic electrolyses of concentrated reactants occuring at a voltage below that of the room temperature energy stored in the products. One example is CO(2) , which is reduced to either fuels or storable carbon at a solar efficiency of over 50% due to a synergy of efficient solar thermal absorption and electrochemical conversion at high temperature and reactant concentration. CO(2) -free production of iron by STEP, from iron ore, occurs via Fe(III) in molten carbonate. Water is efficiently split to hydrogen by molten hydroxide electrolysis, and chlorine, sodium, and magnesium from molten chlorides. A pathway is provided for the STEP decrease of atmospheric carbon dioxide levels to pre-industial age levels in 10 years. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
New method for calculation of integral characteristics of thermal plumes
DEFF Research Database (Denmark)
Zukowska, Daria; Popiolek, Zbigniew; Melikov, Arsen Krikor
2008-01-01
of the directional velocity (upward component of the mean velocity). The method is applied for determination of the characteristics of an asymmetric thermal plume generated by a sitting person. The method was validated in full-scale experiments in a climatic chamber with a thermal manikin as a simulator of a sitting...
Gas Analysis and Control Methods for Thermal Batteries
2013-09-01
HURST 3 EAGLE PICHER TECHNOLOGIES LLC (PDFS) JIM FERRARO CHARLEY LAMB DHARMESH BHAKTA 3 THE ENSER CORPORATION (PDFS) ROY JACKSON...Gas Analysis and Control Methods for Thermal Batteries by Frank C. Krieger and Michael S. Ding ARL-TR-6665 September 2013...September 2013 Gas Analysis and Control Methods for Thermal Batteries Frank C. Krieger and Michael S. Ding Sensors and Electron Devices
Qi, Huijie; Niu, Lihong; Zhang, Jie; Chen, Jian; Wang, Shujie; Yang, Jingjing; Guo, Siyi; Lawson, Tom; Shi, Bingyang; Song, Chunpeng
2018-04-01
Surface plasmon resonance (SPR) nanosensors based on metallic nanohole arrays have been widely reported to detect binding interactions in biological specimens. A simple and effective method for constructing nanoscale arrays is essential for the development of SPR nanosensors. In this work, we report a one-step method to fabricate nanohole arrays by thermal nanoimprinting in the matrix of IPS (Intermediate Polymer Stamp). No additional etching process or supporting substrate is required. The preparation process is simple, time-saving and compatible for roll-to-roll process, potentially allowing mass production. Moreover, the nanohole arrays were integrated into detection platform as SPR sensors to investigate different types of biological binding interactions. The results demonstrate that our one-step method can be used to efficiently fabricate large-area and uniform nanohole arrays for biochemical sensing.
Directory of Open Access Journals (Sweden)
Kang Ma
2017-01-01
Full Text Available Coherent gradient sensing (CGS method can be used to measure the slope of a reflective surface, and has the merits of full-field, non-contact, and real-time measurement. In this study, the thermal stress field of thermal barrier coating (TBC structures is measured by CGS method. Two kinds of powders were sprayed onto Ni-based alloy using a plasma spraying method to obtain two groups of film–substrate specimens. The specimens were then heated with an oxy-acetylene flame. The resulting thermal mismatch between the film and substrate led to out-of-plane deformation of the specimen. The deformation was measured by the reflective CGS method and the thermal stress field of the structure was obtained through calibration with the help of finite element analysis. Both the experiment and numerical results showed that the thermal stress field of TBC structures can be successfully measured by CGS method.
Thermal stresses in long prisms by relaxation methods
International Nuclear Information System (INIS)
Cummins, J.D.
1959-07-01
A general method is presented for calculating the elastic thermal stresses in long prisms which are producing heat and are not solvable by simple analytical methods. The problem of an inverted lattice i.e. an hexagonal coolant passage surrounded by hexagonal fuel elements is considered and the temperature and principal thermal stress distributions evaluated for the particular case of 20% coolant. The maximum thermal stress for this type of fuel element is about the same as the maximum thermal stress in a cylindrical fuel element surrounded by a sea of coolant assuming the existence of the same maximum temperature drop and material properties. (author)
Measurement of through-thickness thermal diffusivity of thermoplastics using thermal wave method
Singh, R.; Mellinger, A.
2015-04-01
Thermo-physical properties, such as thermal conductivity, thermal diffusivity and specific heat are important quantities that are needed to interpret and characterize thermoplastic materials. Such characterization is necessary for many applications, ranging from aerospace engineering to food packaging, electrical and electronic industry and medical science. In this work, the thermal diffusivity of commercially available polymeric films is measured in the thickness direction at room temperature using thermal wave method. The results obtained with this method are in good agreement with theoretical and experimental values.
DEFF Research Database (Denmark)
Bording, Thue Sylvester; Nielsen, Søren Bom; Balling, Niels
2016-01-01
and thermal properties are estimated by inverse Monte Carlo modelling. This methodology enables a proper quantification of experimental uncertainties on measured thermal properties. The developed methodology was applied to laboratory measurements of various materials, including a standard ceramic material......Accurate information on thermal conductivity and thermal diffusivity of materials is of central importance in relation to geoscience and engineering problems involving the transfer of heat. Within the geosciences, this applies to all aspects regarding the determination of terrestrial heat flow...... and subsurface temperature modelling. Several methods, including the classical divided-bar technique, are available for laboratory measurements of thermal conductivity, and much fewer for thermal diffusivity. We have generalized the divided-bar technique to the transient case, in which thermal conductivity...
Troubleshooting in gene splicing by overlap extension: a step-wise method.
Mergulhão, F J; Kelly, A G; Monteiro, G A; Taipa, M A; Cabral, J M
1999-10-01
A step-wise method for cloning intron-containing genes from genomic DNA is described. The two exons of the human proinsulin gene were separately amplified in two steps using, in the first step, completely homologous primers. This reduces unwanted interactions between mismatched primers and a complex DNA template such as genomic DNA. The fragments were amplified in a second step polymerase chain reaction (PCR) using mismatched primers that incorporated additional bases complementary to the other exon, and these products were spliced together in a third step PCR.
Han, Yaohui; Mou, Lan; Xu, Gengchi; Yang, Yiqiang; Ge, Zhenlin
2015-03-01
To construct a three-dimensional finite element model comparing between one-step and two-step methods in torque control of anterior teeth during space closure. Dicom image data including maxilla and upper teeth were obtained though cone-beam CT. A three-dimensional model was set up and the maxilla, upper teeth and periodontium were separated using Mimics software. The models were instantiated using Pro/Engineer software, and Abaqus finite element analysis software was used to simulate the sliding mechanics by loading 1.47 Nforce on traction hooks with different heights (2, 4, 6, 8, 10, 12 and 14 mm, respectively) in order to compare the initial displacement between six maxillary anterior teeth (one-step method) and four maxillary anterior teeth (two-step method). When moving anterior teeth bodily, initial displacements of central incisors in two-step method and in one-step method were 29.26 × 10⁻⁶ mm and 15.75 × 10⁻⁶ mm, respectively. The initial displacements of lateral incisors in two-step method and in one-step method were 46.76 × 10(-6) mm and 23.18 × 10(-6) mm, respectively. Under the same amount of light force, the initial displacement of anterior teeth in two-step method was doubled compared with that in one-step method. The root and crown of the canine couldn't obtain the same amount of displacement in one-step method. Two-step method could produce more initial displacement than one-step method. Therefore, two-step method was easier to achieve torque control of the anterior teeth during space closure.
Improved Full-Newton-Step Infeasible Interior-Point Method for Linear Complementarity Problems
Directory of Open Access Journals (Sweden)
Goran Lešaja
2016-04-01
Full Text Available We present an Infeasible Interior-Point Method for monotone Linear Complementarity Problem (LCP which is an improved version of the algorithm given in [13]. In the earlier version, each iteration consisted of one feasibility step and few centering steps. The improved version guarantees that after one feasibility step, the new iterate is feasible and close enough to the central path thanks to the much tighter proximity estimate which is based on the new lemma introduced in [18]. Thus, the centering steps are eliminated. Another advantage of this method is the use of full-Newton-steps, that is, no calculation of the step size is required. The preliminary implementation and numerical results demonstrate the advantage of the improved version of the method in comparison with the old one.
The method validation step of biological dosimetry accreditation process
International Nuclear Information System (INIS)
Roy, L.; Voisin, P.A.; Guillou, A.C.; Busset, A.; Gregoire, E.; Buard, V.; Delbos, M.; Voisin, Ph.
2006-01-01
One of the missions of the Laboratory of Biological Dosimetry (L.D.B.) of the Institute for Radiation and Nuclear Safety (I.R.S.N.) is to assess the radiological dose after an accidental overexposure suspicion to ionising radiation, by using radio-induced changes of some biological parameters. The 'gold standard' is the yield of dicentrics observed in patients lymphocytes, and this yield is converted in dose using dose effect relationships. This method is complementary to clinical and physical dosimetry, for medical team in charge of the patients. To obtain a formal recognition of its operational activity, the laboratory decided three years ago, to require an accreditation, by following the recommendations of both 17025 General Requirements for the Competence of Testing and Calibration Laboratories and 19238 Performance criteria for service laboratories performing biological dosimetry by cyto-genetics. Diagnostics, risks analysis were realized to control the whole analysis process leading to documents writing. Purchases, personnel department, vocational training were also included in the quality system. Audits were very helpful to improve the quality system. One specificity of this technique is that it is not normalized therefore apart from quality management aspects, several technical points needed some validations. An inventory of potentially influent factors was carried out. To estimate their real effect on the yield of dicentrics, a Placket-Burman experimental design was conducted. The effect of seven parameters was tested: the BUdr (bromodeoxyuridine), PHA (phytohemagglutinin) and colcemid concentration, the culture duration, the incubator temperature, the blood volume and the medium volume. The chosen values were calculated according to the uncertainties on the way they were measured i.e. pipettes, thermometers, test tubes. None of the factors has a significant impact on the yield of dicentrics. Therefore the uncertainty linked to their use was considered as
A Two-Step RKC Method for Time-Dependent PDEs
International Nuclear Information System (INIS)
Sommeijer, Ben; Verwer, Jan
2008-01-01
An integration method is discussed which has been designed to treat parabolic and hyperbolic terms explicitly and stiff reaction terms implicitly. The method is a special two-step form of the one-step IMEX (IMplicit-EXplicit) RKC (Runge-Kutta-Chebyshev) method. The special two-step form is introduced with the aim of getting a non-zero imaginary stability boundary which is zero for the one-step method. Having a non-zero imaginary stability boundary allows, for example, the integration of pure advection equations space-discretized with centered schemes, the integration of damped or viscous wave equations, the integration of coupled sound and heat flow equations, etc. For our class of methods it also simplifies the choice of temporal step sizes satisfying the von Neumann stability criterion, by embedding a thin long rectangle inside the stability region.
Graphene nanoplatelets: Thermal diffusivity and thermal conductivity by the flash method
Directory of Open Access Journals (Sweden)
M. Potenza
2017-07-01
Full Text Available The present work deals with the measurement of thermo-physical properties of a freestanding sheet of graphene (thermal diffusivity and thermal conductivity, and their dependence on sample density as result of uniform mechanical compression. Thermal diffusivity of graphene nano-platelets (thin slabs was measured by the pulse flash method. Obtained response data were processed with a specifically developed least square data processing algorithm. GNP specific heat was assumed from literature and thermal conductivity derived from thermal diffusivity, specific heat and density. Obtained results show a significant difference with respect to other porous media: the thermal diffusivity decreases as the density increases, while thermal conductivity increases for low and high densities, and remain fairly constant for the intermediate range. This can be explained by the very high thermal conductivity values reached by the nano-layers of graphene and the peculiar arrangement of platelets during the compression applied to the samples to get the desired density. Due to very high thermal conductivity of graphene layers, the obtained results show that thermal conductivity of conglomerates increases when there is an air reduction due to compression, and consequent density increases, with the number of contact points between platelets also increased. In the intermediate range (250 ≤ ρ ≤ 700 kg·m-3 the folding of platelets reduces density, without increasing the contact points of platelets, so thermal conductivity can slightly decrease.
Directory of Open Access Journals (Sweden)
Gao Hongding
2012-07-01
Full Text Available Abstract Background A single-step blending approach allows genomic prediction using information of genotyped and non-genotyped animals simultaneously. However, the combined relationship matrix in a single-step method may need to be adjusted because marker-based and pedigree-based relationship matrices may not be on the same scale. The same may apply when a GBLUP model includes both genomic breeding values and residual polygenic effects. The objective of this study was to compare single-step blending methods and GBLUP methods with and without adjustment of the genomic relationship matrix for genomic prediction of 16 traits in the Nordic Holstein population. Methods The data consisted of de-regressed proofs (DRP for 5 214 genotyped and 9 374 non-genotyped bulls. The bulls were divided into a training and a validation population by birth date, October 1, 2001. Five approaches for genomic prediction were used: 1 a simple GBLUP method, 2 a GBLUP method with a polygenic effect, 3 an adjusted GBLUP method with a polygenic effect, 4 a single-step blending method, and 5 an adjusted single-step blending method. In the adjusted GBLUP and single-step methods, the genomic relationship matrix was adjusted for the difference of scale between the genomic and the pedigree relationship matrices. A set of weights on the pedigree relationship matrix (ranging from 0.05 to 0.40 was used to build the combined relationship matrix in the single-step blending method and the GBLUP method with a polygenetic effect. Results Averaged over the 16 traits, reliabilities of genomic breeding values predicted using the GBLUP method with a polygenic effect (relative weight of 0.20 were 0.3% higher than reliabilities from the simple GBLUP method (without a polygenic effect. The adjusted single-step blending and original single-step blending methods (relative weight of 0.20 had average reliabilities that were 2.1% and 1.8% higher than the simple GBLUP method, respectively. In
Thermal conductivity measurement of liquid uranium dioxide by transient method
International Nuclear Information System (INIS)
Degiovanni, A.; Remy, B.
2006-01-01
This work deals with a new measurement method of the thermal conductivity of uranium dioxide in liquid phase. The sample, initially in the solid form, is heated above the melting point by a laser pulse. The temperature variation of the heated zone is measured with a fast pyrometer and allows to recover the thermal conductivity of the liquid using an inverse method. The uncertainty obtained by this method is significantly lower to the one encountered in the literature. (J.S.)
Method and apparatus for measuring thermal neutron characteristics
International Nuclear Information System (INIS)
Jacobson, L.A.; Johnstone, C.M.
1980-01-01
A system of measuring the thermal neutron decay characteristics of an earth formation is described. The method consists of detecting indications of the thermal neutron concentration in the formation during a selected set of two measurement intervals following irradiation of the formation with a burst of fast neutrons. (U.K.)
Effect of thermal processing methods on the proximate composition ...
African Journals Online (AJOL)
The nutritive value of raw and thermal processed castor oil seed (Ricinus communis) was investigated using the following parameters; proximate composition, gross energy, mineral constituents and ricin content. Three thermal processing methods; toasting, boiling and soaking-and-boiling were used in the processing of the ...
Conceptual framework for the thermal distribution method of test
Energy Technology Data Exchange (ETDEWEB)
Andrews, J.W.
1994-11-01
A Standard Method of Test for residential thermal distribution efficiency is being developed under the auspices of the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). Thermal distribution systems are the ductwork, piping, or other means used to transport heat or cooling effect from the equipment that produces this thermal energy to the building spaces that need it. Because thermal distribution systems are embedded in and interact with the larger building system as a whole, a new set of parameters has been developed to describe these systems. This paper was written to fill a perceived need for a concise introduction to this terminology.
Influences in Thermal Conductivity Evaluation Using the Thermal Probe Method; some Practical Aspects
Strâmbu, Vasile
2012-01-01
The thermal probe is a device used for measuring the thermal conductivity of materials in the food industry, plastics industry, geotechnical engineering and studies of soft soils and rocks. The method also started being utilized in the field of construction materials with particularities that take into account their composition and the state they are in.
Method and apparatus for implementing material thermal property measurement by flash thermal imaging
Energy Technology Data Exchange (ETDEWEB)
Sun, Jiangang
2017-11-14
A method and apparatus are provided for implementing measurement of material thermal properties including measurement of thermal effusivity of a coating and/or film or a bulk material of uniform property. The test apparatus includes an infrared camera, a data acquisition and processing computer coupled to the infrared camera for acquiring and processing thermal image data, a flash lamp providing an input of heat onto the surface of a two-layer sample with an enhanced optical filter covering the flash lamp attenuating an entire infrared wavelength range with a series of thermal images is taken of the surface of the two-layer sample.
Improved Full-Newton Step O(nL) Infeasible Interior-Point Method for Linear Optimization
Gu, G.; Mansouri, H.; Zangiabadi, M.; Bai, Y.Q.; Roos, C.
2009-01-01
We present several improvements of the full-Newton step infeasible interior-point method for linear optimization introduced by Roos (SIAM J. Optim. 16(4):1110–1136, 2006). Each main step of the method consists of a feasibility step and several centering steps. We use a more natural feasibility step,
A Control Method Based on Modal Transformation for Biped Robots to Climb Unknown Steps
Shimmyo, Shuhei; Nakazato, Miki; Mikami, Kei; Sato, Tomoya; Sakaino, Sho; Ohnishi, Kouhei
This paper proposes a control method based on modal transformation for biped robots to climb unknown steps. This method is able to control the foot position of the biped robot and the ground reaction force acting in vertical direction when the biped robot climbs unknown steps in a double-support phase. The effectiveness of the proposed method is confirmed by simulation and experimental results.
Detection of protein concentrations using a pH-step titration method
Kruise, J.; Kruise, J.; Eijkel, Jan C.T.; Bergveld, Piet
1997-01-01
A stimulus-response method based on the application of a pH step is proposed for the detection of protein immobilized in a membrane on top of an ion-sensitive field-effect transistor (ISFET). The ISFET response to a step-wise change in pH, applied at the interface between the membrane and the
ALTERNATIVE METHOD FOR ON SITE EVALUATION OF THERMAL TRANSMITTANCE
Directory of Open Access Journals (Sweden)
Aleksandar Janković
2017-08-01
Full Text Available Thermal transmittance or U-value is an indicator of the building envelope thermal properties and a key parameter for evaluation of heat losses through the building elements due to heat transmission. It can be determined by calculation based on thermal characteristics of the building element layers. However, this value does not take into account the effects of irregularities and degradation of certain elements of the envelope caused by aging, which may lead to errors in calculation of the heat losses. An effective and simple method for determination of thermal transmittance is in situ measurement, which is governed by the ISO 9869-1:2014 that defines heat flow meter method. This relatively expensive method leaves marks and damages surface of the building element. Furthermore, the final result is not always reliable, in particular when the building element is light or when the weather conditions are not suitable. In order to avoid the above mentioned problems and to estimate the real thermal transmittance value an alternative experimental method, here referred as the natural convection and radiation method, is proposed in this paper. For determination of thermal transmittance, this method requires only temperatures of inside and outside air, as well as the inner wall surface temperature. A detailed statistical analysis, performed by the software package SPSS ver. 20, shows several more advantages of this method comparing to the standard heat flow meter one, besides economic and non-destructive benefits.
A semi-Lagrangian method for DNS with large time-stepping
Xiu, Dongbin; Karniadakis, George
2000-11-01
An efficient time-step discretization based on semi-Lagrangian methods, often used in metereology, is proposed for direct numerical simulations. It is unconditionally stable and retains high-order accuracy comparable to Eulerian schemes. The structure of the total error is analyzed in detail, and shows a non-monotonic trend with the size of the time-step. Numerical experiments for a variety of flows shows that stable and accurate results are obtained with time steps more than fifty times the CFL-bound time step used in current semi-implicit DNS.
Some non-thermal microbial inactivation methods in dairy products
International Nuclear Information System (INIS)
Yangilar, F.; Kabil, E.
2013-01-01
During the production of dairy products, some thermal processes such as pasteurization and sterilization are used commonly to inactive microorganisms. But as a result of thermal processes, loss of nutrient and aroma, non-enzymatic browning and organoleptic differentiation especially in dairy products are seen. Because of this, alternative methods are needed to provide microbial inactivation and as major problems are caused by high temperatures, non-thermal processes are focused on. For this purpose, some methods such as high pressure (HP), pulsed light (PL), ultraviolet radiation (UV), supercritical carbon dioxide (SC-CO2) or pulsed electric field (PEF) are used in food. These methods products are processed in ambient temperature and so not only mentioned losses are minimized but also freshness and naturality of products can be preserved. In this work, we will try to be given information about methods of non-thermal microbial inactivation of dairy products. (author) [tr
Simultaneous measurement of thermal conductivity and heat capacity by flash thermal imaging methods
Tao, N.; Li, X. L.; Sun, J. G.
2017-06-01
Thermal properties are important for material applications involved with temperature. Although many measurement methods are available, they may not be convenient to use or have not been demonstrated suitable for testing of a wide range of materials. To address this issue, we developed a new method for the nondestructive measurement of the thermal effusivity of bulk materials with uniform property. This method is based on the pulsed thermal imaging-multilayer analysis (PTI-MLA) method that has been commonly used for testing of coating materials. Because the test sample for PTI-MLA has to be in a two-layer configuration, we have found a commonly used commercial tape to construct such test samples with the tape as the first-layer material and the bulk material as the substrate. This method was evaluated for testing of six selected solid materials with a wide range of thermal properties covering most engineering materials. To determine both thermal conductivity and heat capacity, we also measured the thermal diffusivity of these six materials by the well-established flash method using the same experimental instruments with a different system setup. This paper provides a description of these methods, presents detailed experimental tests and data analyses, and discusses measurement results and their comparison with literature values.
Simultaneous measurement of thermal conductivity and heat capacity by flash thermal imaging methods.
Tao, N; Li, X L; Sun, J G
2017-06-01
Thermal properties are important for material applications involved with temperature. Although many measurement methods are available, they may not be convenient to use or have not been demonstrated suitable for testing of a wide range of materials. To address this issue, we developed a new method for the nondestructive measurement of the thermal effusivity of bulk materials with uniform property. This method is based on the pulsed thermal imaging-multilayer analysis (PTI-MLA) method that has been commonly used for testing of coating materials. Because the test sample for PTI-MLA has to be in a two-layer configuration, we have found a commonly used commercial tape to construct such test samples with the tape as the first-layer material and the bulk material as the substrate. This method was evaluated for testing of six selected solid materials with a wide range of thermal properties covering most engineering materials. To determine both thermal conductivity and heat capacity, we also measured the thermal diffusivity of these six materials by the well-established flash method using the same experimental instruments with a different system setup. This paper provides a description of these methods, presents detailed experimental tests and data analyses, and discusses measurement results and their comparison with literature values.
Full-Newton step interior-point methods for conic optimization
Mansouri, H.
2008-01-01
In the theory of polynomial-time interior-point methods (IPMs) two important classes of methods are distinguished: small-update and large-update methods, respectively. Small-update IPMs have the best theoretical iteration bound and IPMs with full-Newton steps belong to this class of methods. Within
Phase change thermal control materials, method and apparatus
Buckley, Theresa M. (Inventor)
2001-01-01
An apparatus and method for metabolic cooling and insulation of a user in a cold environment. In its preferred embodiment the apparatus is a highly flexible composite material having a flexible matrix containing a phase change thermal storage material. The apparatus can be made to heat or cool the body or to act as a thermal buffer to protect the wearer from changing environmental conditions. The apparatus may also include an external thermal insulation layer and/or an internal thermal control layer to regulate the rate of heat exchange between the composite and the skin of the wearer. Other embodiments of the apparatus also provide 1) a path for evaporation or direct absorption of perspiration from the skin of the wearer for improved comfort and thermal control, 2) heat conductive pathways within the material for thermal equalization, 3) surface treatments for improved absorption or rejection of heat by the material, and 4) means for quickly regenerating the thermal storage capacity for reuse of the material. Applications of the composite materials are also described which take advantage of the composite's thermal characteristics. The examples described include a diver's wet suit, ski boot liners, thermal socks, gloves and a face mask for cold weather activities, and a metabolic heating or cooling blanket useful for treating hypothermia or fever patients in a medical setting and therapeutic heating or cooling orthopedic joint supports.
Qing, Wang; Yang, Liu; Yongjian, Sun; Yuzhen, Tong; Guoyi, Zhang
2016-08-01
A new layer transfer technique which comprised double bonding and a step annealing process was utilized to transfer the GaN epilayer from a sapphire substrate to a Mo substrate. Combined with the application of the thermal-stable bonding medium, the resulting two-inch-diameter GaN template showed extremely good stability under high temperature and low stress state. Moreover, no cracks and winkles were observed. The transferred GaN template was suitable for homogeneous epitaxial, thus could be used for the direct fabrication of vertical LED chips as well as power electron devices. It has been confirmed that the double bonding and step annealing technique together with the thermal-stable bonding layer could significantly improve the bonding strength and stress relief, finally enhancing the thermal stability of the transferred GaN template. Project supported by the Guangdong Innovative Research Team Program (No. 2009010044), the China Postdoctoral Science Foundation (No. 2014M562233), the National Natural Science Foundation of Guangdong, China (No. 2015A030312011), and the Opened Fund of the State Key Laboratory on Integrated Optoelectronics (No. IOSKL2014KF17).
International Nuclear Information System (INIS)
Mendez, Andreas S.L.; Mantovani, Luciano; Barbosa, Fabio; Sayago, Carla T.M.; Garcia, Cassia V.; Garcia, Favero R.; Silva, Fabiana E.B. da; Denardin, Elton L.G.; Schapoval, Elfrides E.S.
2011-01-01
Doripenem was characterized through physicochemical and spectroscopic techniques, as well as thermal analysis. TLC (Rf = 0.62) and HPLC (rt = 7.4 min) were found to be adequate to identify the drug. UV and infrared spectra showed similar profile between doripenem bulk and standard. The 1 H and 13 C NMR analysis revealed chemical shifts that allowed identifying the drug. Thermal analysis demonstrated three steps with mass loss, at 128, 178 and 276 degree C. The work was successfully applied to qualitative analysis of doripenem, showing the reported methods can be used for physicochemical characterization of doripenem. (author)
Energy Technology Data Exchange (ETDEWEB)
Mendez, Andreas S.L.; Mantovani, Luciano; Barbosa, Fabio; Sayago, Carla T.M.; Garcia, Cassia V.; Garcia, Favero R.; Silva, Fabiana E.B. da; Denardin, Elton L.G. [Universidade Federal do Pampa, Uruguaiana, RS (Brazil). Curso de Farmacia; Schapoval, Elfrides E.S. [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Dept. de Producao e Controle de Medicamentos
2011-07-01
Doripenem was characterized through physicochemical and spectroscopic techniques, as well as thermal analysis. TLC (Rf = 0.62) and HPLC (rt = 7.4 min) were found to be adequate to identify the drug. UV and infrared spectra showed similar profile between doripenem bulk and standard. The {sup 1}H and {sup 13}C NMR analysis revealed chemical shifts that allowed identifying the drug. Thermal analysis demonstrated three steps with mass loss, at 128, 178 and 276 degree C. The work was successfully applied to qualitative analysis of doripenem, showing the reported methods can be used for physicochemical characterization of doripenem. (author)
International Nuclear Information System (INIS)
Boergers, C.; Peskin, C.S.
1987-01-01
In the Lagrangian fractional step method introduced in this paper, the fluid velocity and pressure are defined on a collection of N fluid markers. At each time step, these markers are used to generate a Voronoi diagram, and this diagram is used to construct finite-difference operators corresponding to the divergence, gradient, and Laplacian. The splitting of the Navier--Stokes equations leads to discrete Helmholtz and Poisson problems, which we solve using a two-grid method. The nonlinear convection terms are modeled simply by the displacement of the fluid markers. We have implemented this method on a periodic domain in the plane. We describe an efficient algorithm for the numerical construction of periodic Voronoi diagrams, and we report on numerical results which indicate the the fractional step method is convergent of first order. The overall work per time step is proportional to N log N. copyright 1987 Academic Press, Inc
Thermally Self-Healing Polymeric Materials : The Next Step to Recycling Thermoset Polymers?
Zhang, Youchun; Broekhuis, Antonius A.; Picchioni, Francesco
2009-01-01
We developed thermally self-healing polymeric materials on the basis of furan-functionalized, alternating thermosetting polyketones (PK-furan) and bis-maleimide by using the Diels-Alder (DA) and Retro-Diels-Alder (RDA) reaction sequence. PK-furan can be easily obtained under mild conditions by the
Method for quick thermal tolerancing of optical systems
Werschnik, J.; Uhlendorf, K.
2016-09-01
Optical systems for lithography (projection lens), inspection (micro-objectives) or laser material processing usually have tight specifications regarding focus and wave-front stability. The same is true regarding the field dependent properties. Especially projection lenses have tight specifications on field curvature, magnification and distortion. Unwanted heating either from internal or external sources lead to undesired changes of the above properties. In this work we show an elegant and fast method to analyze the thermal sensitivity using ZEMAX. The key point of this method is using the thermal changes of the lens data from the multi-configuration editor as starting point for a (standard) tolerance analysis. Knowing the sensitivity we can either define requirements on the environment or use it to systematically improve the thermal behavior of the lens. We demonstrate this method for a typical projection lens for which we optimized the thermal field curvature to a minimum.
Comparison between ASHRAE and ISO thermal transmittance calculation methods
DEFF Research Database (Denmark)
Blanusa, Petar; Goss, William P.; Roth, Hartwig
2007-01-01
. The fenestration thermal transmittance calculations analyses presented in this paper show that small differences exist between the calculated thermal transmittance values produced by the ISO and ASHRAE methods. The results also show that the overall thermal transmittance difference between the two methodologies...... decreases as the total window area (glazing plus frame) increases. Thus, the resulting difference in thermal transmittance values for the two methods is negligible for larger windows. This paper also shows algebraically that the differences between the ISO and ASHRAE methods turn out to be due to the way......The intent of this paper is to describe and compare the two different two-dimensional frame/spacer heat transfer calculation methodologies used in North America (FRAME [EEL. The FRAMEplus Toolkit for Heat Transfer Assessment of Building Components, Version 3.0, Enermodal Engineering, Kichener...
A hybrid method without extrapolation step for solving variational inequality problems
Malitsky, Yu. V.; Semenov, V. V.
2015-01-01
In this paper, we introduce a new method for solving variational inequality problems with monotone and Lipschitz-continuous mapping in Hilbert space. The iterative process is based on two well-known projection method and the hybrid (or outer approximation) method. However we do not use an extrapolation step in the projection method. The absence of one projection in our method is explained by slightly different choice of sets in hybrid method. We prove a strong convergence of the sequences gen...
Development of a thermal method for the measurement of elemental carbon
Energy Technology Data Exchange (ETDEWEB)
Lavanchy, V.M.H. [Bern Univ. (Switzerland); Baltensperger, U.; Gaeggeler, H.W. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)
1997-09-01
A thermal method was developed to measure the organic carbon (OC) and elemental carbon (EC) content of atmospheric aerosols. OC is first oxidized under an O{sub 2} flow during a precombustion step and measured with an Non-Dispersive Infrared Analyzer (NDIR). The remaining carbon, defined as EC, is then oxidized at 650{sup o}C. (author) 1 fig., 1 tab., 3 refs.
Variable Step-Size Method Based on a Reference Separation System for Source Separation
Directory of Open Access Journals (Sweden)
Pengcheng Xu
2015-01-01
Full Text Available Traditional variable step-size methods are effective to solve the problem of choosing step-size in adaptive blind source separation process. But the initial setting of learning rate is vital, and the convergence speed is still low. This paper proposes a novel variable step-size method based on reference separation system for online blind source separation. The correlation between the estimated source signals and original source signals increases along with iteration. Therefore, we introduce a reference separation system to approximately estimate the correlation in terms of mean square error (MSE, which is utilized to update the step-size. The use of “minibatches” for the computation of MSE can reduce the complexity of the algorithm to some extent. Moreover, simulations demonstrate that the proposed method exhibits superior convergence and better steady-state performance over the fixed step-size method in the noise-free case, while converging faster than classical variable step-size methods in both stationary and nonstationary environments.
Method and apparatus for thermal energy storage. [Patent application
Gruen, D.M.
1975-08-19
A method and apparatus for storing energy by converting thermal energy to potential chemically bound energy in which a first metal hydride is heated to dissociation temperature, liberating hydrogen gas which is compressed and reacted with a second metal to form a second metal hydride while releasing thermal energy. Cooling the first metal while warming the second metal hydride to dissociation temperature will reverse the flow of hydrogen gas back to the first metal, releasing additional thermal energy. The method and apparatus are particularly useful for the storage and conversion of thermal energy from solar heat sources and for the utilization of this energy for space heating purposes, such as for homes or offices.
Comparison of Model Reliabilities from Single-Step and Bivariate Blending Methods
DEFF Research Database (Denmark)
Taskinen, Matti; Mäntysaari, Esa; Lidauer, Martin
2013-01-01
the production trait evaluation of Nordic Red dairy cattle. Genotyped bulls with daughters are used as training animals, and genotyped bulls and producing cows as candidate animals. For simplicity, size of the data is chosen so that the full inverses of the mixed model equation coefficient matrices can......Model based reliabilities in genetic evaluation are compared between three methods: animal model BLUP, single-step BLUP, and bivariate blending after genomic BLUP. The original bivariate blending is revised in this work to better account animal models. The study data is extracted from...... be calculated. Model reliabilities by the single-step and the bivariate blending methods were higher than by animal model due to genomic information. Compared to the single-step method, the bivariate blending method reliability estimates were, in general, lower. Computationally bivariate blending method was...
Evaluation of thermal radiation simulator rectangular pulse characterization methods
International Nuclear Information System (INIS)
Loucks, R.B.
1991-01-01
This paper discusses the thermal output of an aluminum powder/liquid oxygen Thermal Radiation Simulator (TRS) which is approximated to that of a rectangular pulse. The output varies as a function of time. The rise and fall times are not relatively abrupt. The problem is how to quantify the thermal output of the TRS into terms of rectangular pulse. Within the nuclear weapons effects community, flux, or the transient intensity of thermal radiation energy onto a surface, and fluence, the total energy irradiated on a surface over a given time, are the determining parameters for specifying or evaluating an article's survivability in the thermal environment. Four methods are used to determine the TRS output for these parameters, assuming the output to be a perfect rectangular pulse. It was essential to determine which of the four methods best quantified the thermal output average flux and fluence. The four methods were compared by a computational experiment run on a personal computer. The experiment was a simulation of five actual TRS traces irradiated onto a fictitious aluminum plate
Real-Time Step Length Control Method for a Biped Robot
Aiko, Takahiro; Ohnishi, Kouhei
In this paper, the real-time step length control method for a biped robot is proposed. In human environment, it is necessary for a biped robot to change its gait on real-time since it is required to walk according to situations. By use of the proposed method, the center-of-gravity trajectory and swing leg trajectory were generated on real-time with that its command value is the step length. For generating the center-of-gravity trajectory, we develop Linear Inverted Pendulum Mode and additionally consider walking stability by ZMP. In order to demonstrate the proposed method, the simulation and experiment of a biped walk is performed.
Three-Step Hybrid Linear Multistep Method for Solution of First ...
African Journals Online (AJOL)
In this article, a three-step hybrid linear multistep method for solution of first order initial value problems (IVPs) in ordinary differential differential equations (ODEs) is proposed. Essentially, the method is based on collocation of the differential system and the interpolation of the approximate solution at the grid and off-grid ...
Q-Step methods for Newton-Jacobi operator equation | Uwasmusi ...
African Journals Online (AJOL)
The paper considers the Newton-Jacobi operator equation for the solution of nonlinear systems of equations. Special attention is paid to the computational part of this method with particular reference to the q-step methods. Journal of the Nigerian Association of Mathematical Physics Vol. 8 2004: pp. 237-241 ...
DEFF Research Database (Denmark)
Zhu, Yansong; Jha, Abhinav K.; Dreyer, Jakob K.
2017-01-01
effects could be exploited, traditional compressive-sensing methods cannot be directly applied as the system matrix in FMT is highly coherent. To overcome these issues, we propose and assess a three-step reconstruction method. First, truncated singular value decomposition is applied on the data to reduce...... considerable promise and will be tested using more realistic simulations and experimental setups....
Some selected quantitative methods of thermal image analysis in Matlab.
Koprowski, Robert
2016-05-01
The paper presents a new algorithm based on some selected automatic quantitative methods for analysing thermal images. It shows the practical implementation of these image analysis methods in Matlab. It enables to perform fully automated and reproducible measurements of selected parameters in thermal images. The paper also shows two examples of the use of the proposed image analysis methods for the area of the skin of a human foot and face. The full source code of the developed application is also provided as an attachment. The main window of the program during dynamic analysis of the foot thermal image. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Energy Technology Data Exchange (ETDEWEB)
Vogli, Evelina; Sherman, Andrew J.; Glasgow, Curtis P.
2018-02-06
The invention describes a method for producing ternary and binary ceramic powders and their thermal spraying capable of manufacturing thermal sprayed coatings with superior properties. Powder contain at least 30% by weight ternary ceramic, at least 20% by weight binary molybdenum borides, at least one of the binary borides of Cr, Fe, Ni, W and Co and a maximum of 10% by weight of nano and submicro-sized boron nitride. The primary crystal phase of the manufactured thermal sprayed coatings from these powders is a ternary ceramic, while the secondary phases are binary ceramics. The coatings have extremely high resistance against corrosion of molten metal, extremely thermal shock resistance and superior tribological properties at low and at high temperatures.
Directory of Open Access Journals (Sweden)
Kaisheng Zhang
2014-07-01
Full Text Available According to the characteristics of photovoltaic cell output power curve, this paper analyzed and explained the principle of Maximum Power Point Tracking (MPPT and both advantages and disadvantages of constant voltage tracking method & perturbation observation method. Further, in combination with the advantages of existing maximum power tracking methods, this paper comes up with an improved tracking method which is recognized as maximum power point tracking combined with constant voltage tracking method & variable step-size perturbation observation method. The Simulink simulation results have proven this enhanced tracking method has a better performance in System response and steady state characteristics.
Zhao, Fanglong; Zhang, Chuanbo; Yin, Jing; Shen, Yueqi; Lu, Wenyu
2015-08-01
In this paper, a two-step resin adsorption technology was investigated for spinosad production and separation as follows: the first step resin addition into the fermentor at early cultivation period to decrease the timely product concentration in the broth; the second step of resin addition was used after fermentation to adsorb and extract the spinosad. Based on this, a two-step macroporous resin adsorption-membrane separation process for spinosad fermentation, separation, and purification was established. Spinosad concentration in 5-L fermentor increased by 14.45 % after adding 50 g/L macroporous at the beginning of fermentation. The established two-step macroporous resin adsorption-membrane separation process got the 95.43 % purity and 87 % yield for spinosad, which were both higher than that of the conventional crystallization of spinosad from aqueous phase that were 93.23 and 79.15 % separately. The two-step macroporous resin adsorption method has not only carried out the coupling of spinosad fermentation and separation but also increased spinosad productivity. In addition, the two-step macroporous resin adsorption-membrane separation process performs better in spinosad yield and purity.
Method for enhancing the thermal stability of ionic compounds
DEFF Research Database (Denmark)
2013-01-01
This invention relates to a method for enhancing the thermal stability of ionic compounds including ionic liquids, by immobilization on porous solid support materials having a pore diameter of between about 20-200 AA, wherein the solid support does not have a pore size of 90 AA.......This invention relates to a method for enhancing the thermal stability of ionic compounds including ionic liquids, by immobilization on porous solid support materials having a pore diameter of between about 20-200 AA, wherein the solid support does not have a pore size of 90 AA....
Modified Step Variational Iteration Method for Solving Fractional Biochemical Reaction Model
Directory of Open Access Journals (Sweden)
R. Yulita Molliq
2011-01-01
Full Text Available A new method called the modification of step variational iteration method (MoSVIM is introduced and used to solve the fractional biochemical reaction model. The MoSVIM uses general Lagrange multipliers for construction of the correction functional for the problems, and it runs by step approach, which is to divide the interval into subintervals with time step, and the solutions are obtained at each subinterval as well adopting a nonzero auxiliary parameter ℏ to control the convergence region of series' solutions. The MoSVIM yields an analytical solution of a rapidly convergent infinite power series with easily computable terms and produces a good approximate solution on enlarged intervals for solving the fractional biochemical reaction model. The accuracy of the results obtained is in a excellent agreement with the Adam Bashforth Moulton method (ABMM.
International Nuclear Information System (INIS)
Ortega, Alejandra; Alarcón, Darío; Muñoz-Muñoz, Franklin; Garzón-Fontecha, Angélica; Burillo, Guillermina
2015-01-01
Acrylic acid (AAc) and 4-vinyl pyridine (4VP) were γ-ray grafted onto nylon-6 (Ny 6 ) films via pre-irradiation oxidative method. These monomers were grafted using a one-step method to render Ny 6 -g–(AAc/4VP). A two-step or sequential method was used to render (Ny 6 -g–AAc)-g–4VP. Random copolymer branches were obtained when the grafting was carried out via one-step method using the two monomers together. The two-step method was applied to graft chains of 4VP on both Ny 6 substrate and previously grafted AAc chains (Ny 6 -g–AAc). The two types of binary copolymers synthesized were characterized to determine the amount of grafted polymers, the thermal behavior (DSC and TGA), the surface composition (XPS), and the pH responsiveness. In the two-step process, it is possible to achieve a higher graft yield, better control of the amount of each monomer, good reversibility in the swelling/deswelling process and shorter time to achieve equilibrium swelling. - Highlights: • A new binary graft of 4VP and AAc onto Ny 6 films was synthesized by γ-radiation. • The binary grafted material has potential application for heavy ion retention. • The two-step method shows better conditions in swelling and reversibility properties. • Surface distribution of monomers was evaluate by XPS characterization
Thermal properties of flax fiber scoured by different methods
Directory of Open Access Journals (Sweden)
Zheng Dong
2015-01-01
Full Text Available Thermal properties of flax roves untreated and treated were characterized by differential scanning calorimetry (DSC and thermal gravity analyzer (TGA in order to understand their thermal behavior in more detail and to evaluate the effect of scouring processing on the thermal behavior. Flax roves were treated with six kinds of methods including biological scouring, one bath, two bath, bleaching, alkali scouring and industry chemical scouring as standards. Results showed that all treatments improved thermal stability of flax roves. The results indicated that glass transition temperature (Tg decreased after scouring besides the sample by directly bleaching. It is more difficult to determine the endothermic peak of flax treated by chemical scouring in industry because it takes a very flat course. A distinct endothermic peak was observed for the untreated flax rove, while a distinct exothermic peak in different temperature interval was revealed for other four treated flax rove samples. For TGA analysis, thermal degradation of flax roves studied consists of three regions of the initial, main, and char decomposition, and the third stage consists of secondary weight loss and carbonization for flax roves with biological scouring, one-bath and two-bath. Besides, different residue left indicates that the bio-scoured flax roves are lost with volatile products and does not contribute to char formation. These results provide valuable preferences for mechanism and top value added application of bio-scouring in flax roves.
Evaluation of Polyesterimide Nanocomposites Using Methods of Thermal Analysis
Gornicka, B.; Gorecki, L.; Gryzlo, K.; Kaczmarek, D.; Wojcieszak, D.
2016-02-01
Polyesterimide resin applied for winding impregnation has been modified by incorporating the hydrophilic and hydrophobic nanosilica, montmorillonite and aluminium oxide. For assessment of the resins in liquid and cured states thermoanalytical methods TG/DSC were used. For pure and nanofilled resins the results of investigation of AFM topography, bond strength, dielectric strength and partial discharge resistance have been also presented. It was found that dielectric and mechanical properties of polyesterimide resin containing hydrophilic silica as well aluminium oxide were much improved as compared to pure resin. Based on our investigations we have found that the methods of thermal analysis may be very useful for evaluation of nanocomposites: DSC/TGA study of resins in the liquid state under dynamic conditions can be applied to pre-select nanocomposites; isothermal TG curves of cured resins can be utilized for thermal stability evaluation; in turn, TG study after thermal ageing of cured resins could confirm the barrier properties of nanocomposites.
Stabilizing the thermal lattice Boltzmann method by spatial filtering.
Gillissen, J J J
2016-10-01
We propose to stabilize the thermal lattice Boltzmann method by filtering the second- and third-order moments of the collision operator. By means of the Chapman-Enskog expansion, we show that the additional numerical diffusivity diminishes in the low-wavnumber limit. To demonstrate the enhanced stability, we consider a three-dimensional thermal lattice Boltzmann system involving 33 discrete velocities. Filtering extends the linear stability of this thermal lattice Boltzmann method to 10-fold smaller transport coefficients. We further demonstrate that the filtering does not compromise the accuracy of the hydrodynamics by comparing simulation results to reference solutions for a number of standardized test cases, including natural convection in two dimensions.
Design of a Two-Step Calibration Method of Kinematic Parameters for Serial Robots
WANG, Wei; WANG, Lei; YUN, Chao
2017-03-01
Serial robots are used to handle workpieces with large dimensions, and calibrating kinematic parameters is one of the most efficient ways to upgrade their accuracy. Many models are set up to investigate how many kinematic parameters can be identified to meet the minimal principle, but the base frame and the kinematic parameter are indistinctly calibrated in a one-step way. A two-step method of calibrating kinematic parameters is proposed to improve the accuracy of the robot's base frame and kinematic parameters. The forward kinematics described with respect to the measuring coordinate frame are established based on the product-of-exponential (POE) formula. In the first step the robot's base coordinate frame is calibrated by the unit quaternion form. The errors of both the robot's reference configuration and the base coordinate frame's pose are equivalently transformed to the zero-position errors of the robot's joints. The simplified model of the robot's positioning error is established in second-power explicit expressions. Then the identification model is finished by the least square method, requiring measuring position coordinates only. The complete subtasks of calibrating the robot's 39 kinematic parameters are finished in the second step. It's proved by a group of calibration experiments that by the proposed two-step calibration method the average absolute accuracy of industrial robots is updated to 0.23 mm. This paper presents that the robot's base frame should be calibrated before its kinematic parameters in order to upgrade its absolute positioning accuracy.
Stability of one-step methods in transient nonlinear heat conduction
International Nuclear Information System (INIS)
Hughes, J.R.
1977-01-01
The purpose of the present work is to ascertain practical stability conditions for one-step methods commonly used in transient nonlinear heat conduction analyses. The class of problems considered is governed by a temporally continuous, spatially discrete system involving the capacity matrix C, conductivity matrix K, heat supply vector, temperature vector and time differenciation. In the linear case, in which K and C are constant, the stability behavior of one-step methods is well known. But in this paper the concepts of stability, appropriate to the nonlinear problem, are thoroughly discussed. They of course reduce to the usual stability criterion for the linear, constant coefficient case. However, for nonlinear problems there are differences and these ideas are of key importance in obtaining practical stability conditions. Of particular importance is a recent result which indicates that, in a sense, the trapezoidal and midpoint families are quivalent. Thus, stability results for one family may be translated into a result for the other. The main results obtained are summarized as follows. The stability behavior of the explicit Euler method in the nonlinear regime is analogous to that for linear problems. In particular, an a priori step size restriction may be determined for each time step. The precise time step restriction on implicit conditionally stable members of the trapezoidal and midpoint families is shown not to be determinable a priori. Of considerable practical significance, unconditionally stable members of the trapezoidal and midpoint families are identified
A simple three step method for selective placement of organic groups in mesoporous silica thin films
Energy Technology Data Exchange (ETDEWEB)
Franceschini, Esteban A. [Gerencia Química, Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica, Av. Gral Paz 1499 (B1650KNA) San Martín, Buenos Aires (Argentina); Llave, Ezequiel de la; Williams, Federico J. [Departamento de Química Inorgánica, Analítica y Química Física and INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón II, C1428EHA Buenos Aires (Argentina); Soler-Illia, Galo J.A.A., E-mail: galo.soler.illia@gmail.com [Departamento de Química Inorgánica, Analítica y Química Física and INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón II, C1428EHA Buenos Aires (Argentina); Instituto de Nanosistemas, Universidad Nacional de General San Martín, 25 de Mayo y Francia (1650) San Martín, Buenos Aires (Argentina)
2016-02-01
Selective functionalization of mesoporous silica thin films was achieved using a three step method. The first step consists in an outer surface functionalization, followed by washing off the structuring agent (second step), leaving the inner surface of the pores free to be functionalized in the third step. This reproducible method permits to anchor a volatile silane group in the outer film surface, and a second type of silane group in the inner surface of the pores. As a concept test we modified the outer surface of a mesoporous silica film with trimethylsilane (–Si–(CH{sub 3}){sub 3}) groups and the inner pore surface with propylamino (–Si–(CH{sub 2}){sub 3}–NH{sub 2}) groups. The obtained silica films were characterized by Environmental Ellipsometric Porosimetry (EEP), EDS, XPS, contact angle and electron microscopy. The selectively functionalized silica (SF) shows an amount of surface amino functions 4.3 times lower than the one-step functionalized (OSF) silica samples. The method presented here can be extended to a combination of silane chlorides and alkoxides as functional groups, opening up a new route toward the synthesis of multifunctional mesoporous thin films with precisely localized organic functions. - Highlights: • Selective functionalization of mesoporous silica thin films was achieved using a three step method. • A volatile silane group is anchored by evaporation on the outer film surface. • A second silane is deposited in the inner surface of the pores by post-grafting. • Contact angle, EDS and XPS measurements show different proportions of amino groups on both surfaces. • This method can be extended to a combination of silane chlorides and alkoxides functional groups.
A two-step method for rapid characterization of electroosmotic flows in capillary electrophoresis.
Zhang, Wenjing; He, Muyi; Yuan, Tao; Xu, Wei
2017-12-01
The measurement of electroosmotic flow (EOF) is important in a capillary electrophoresis (CE) experiment in terms of performance optimization and stability improvement. Although several methods exist, there are demanding needs to accurately characterize ultra-low electroosmotic flow rates (EOF rates), such as in coated capillaries used in protein separations. In this work, a new method, called the two-step method, was developed to accurately and rapidly measure EOF rates in a capillary, especially for measuring the ultra-low EOF rates in coated capillaries. In this two-step method, the EOF rates were calculated by measuring the migration time difference of a neutral marker in two consecutive experiments, in which a pressure driven was introduced to accelerate the migration and the DC voltage was reversed to switch the EOF direction. Uncoated capillaries were first characterized by both this two-step method and a conventional method to confirm the validity of this new method. Then this new method was applied in the study of coated capillaries. Results show that this new method is not only fast in speed, but also better in accuracy. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
A two-step filtering-based iterative image reconstruction method for interior tomography.
Zhang, Hanming; Li, Lei; Yan, Bin; Wang, Linyuan; Cai, Ailong; Hu, Guoen
2016-10-06
The optimization-based method that utilizes the additional sparse prior of region-of-interest (ROI) image, such as total variation, has been the subject of considerable research in problems of interior tomography reconstruction. One challenge for optimization-based iterative ROI image reconstruction is to build the relationship between ROI image and truncated projection data. When the reconstruction support region is smaller than the original object, an unsuitable representation of data fidelity may lead to bright truncation artifacts in the boundary region of field of view. In this work, we aim to develop an iterative reconstruction method to suppress the truncation artifacts and improve the image quality for direct ROI image reconstruction. A novel reconstruction approach is proposed based on an optimization problem involving a two-step filtering-based data fidelity. Data filtering is achieved in two steps: the first takes the derivative of projection data; in the second step, Hilbert filtering is applied in the differentiated data. Numerical simulations and real data reconstructions have been conducted to validate the new reconstruction method. Both qualitative and quantitative results indicate that, as theoretically expected, the proposed method brings reasonable performance in suppressing truncation artifacts and preserving detailed features. The presented local reconstruction method based on the two-step filtering strategy provides a simple and efficient approach for the iterative reconstruction from truncated projections.
Thermal-hydraulic methods in fast reactor safety
International Nuclear Information System (INIS)
Weber, D.P.; Briggs, L.L.
1985-01-01
Methods for the solution of thermal-hydraulic problems in liquid metal fast breeder reactors (LMFBRs) arising primarily from transient accident analysis are reviewed. Principal emphasis is given to the important phenomenological issues of sodium boiling and fuel motion. Descriptions of representative phenomenological and mathematical models, computational algorithms, advantages and limitations of the approaches, and current research needs and directions are provided
A simple method for estimating thermal response of building ...
African Journals Online (AJOL)
This paper develops a simple method for estimating the thermal response of building materials in the tropical climatic zone using the basic heat equation. The efficacy of the developed model has been tested with data from three West African cities, namely Kano (lat. 12.1 ºN) Nigeria, Ibadan (lat. 7.4 ºN) Nigeria and Cotonou ...
Energy Technology Data Exchange (ETDEWEB)
Kim, Sun Hye; Choi, Jae boong; Kim, Moon Ki [Sungkyunkwan Univ., Seoul (Korea, Republic of); Huh, Nam Su [Seoul Nat' l Univ., Seoul (Korea, Republic of); Lee, Jin Ho [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)
2012-10-15
Thermal fatigue cracking induced by thermal stratification, cycling and striping have been observed in several PWR plants. Especially, thermal striping, the highly fluctuating thermal layer, became one of the significant problems, since it can cause un predicted high cycle thermal fatigue (HCTF) at piping systems. This problem are usually found in T junctions of energy cooling systems, where cold and hot flows with high level of turbulence mix together. Thermal striping can cause the networks of fatigue crack at the vicinity of weld parts and these cracks can propagate to significant depth in a relatively short time. Therefore, thermal striping and fatigue crack initiations should be predicted in advance to prevent the severe failure of piping systems. The final goal of this research is to develop a rational thermal and mechanical model considering thermohydraulic characteristics of thermal striping and an evaluation procedure to predict the initiation of thermal fatigue crack. As a first step, we evaluated the fatigue damage in a T junction using two widely used methods. Then, we analyzed the results of each method and conducted comparisons and verifications.
Perturbed Strong Stability Preserving Time-Stepping Methods For Hyperbolic PDEs
Hadjimichael, Yiannis
2017-09-30
A plethora of physical phenomena are modelled by hyperbolic partial differential equations, for which the exact solution is usually not known. Numerical methods are employed to approximate the solution to hyperbolic problems; however, in many cases it is difficult to satisfy certain physical properties while maintaining high order of accuracy. In this thesis, we develop high-order time-stepping methods that are capable of maintaining stability constraints of the solution, when coupled with suitable spatial discretizations. Such methods are called strong stability preserving (SSP) time integrators, and we mainly focus on perturbed methods that use both upwind- and downwind-biased spatial discretizations. Firstly, we introduce a new family of third-order implicit Runge–Kuttas methods with arbitrarily large SSP coefficient. We investigate the stability and accuracy of these methods and we show that they perform well on hyperbolic problems with large CFL numbers. Moreover, we extend the analysis of SSP linear multistep methods to semi-discretized problems for which different terms on the right-hand side of the initial value problem satisfy different forward Euler (or circle) conditions. Optimal perturbed and additive monotonicity-preserving linear multistep methods are studied in the context of such problems. Optimal perturbed methods attain augmented monotonicity-preserving step sizes when the different forward Euler conditions are taken into account. On the other hand, we show that optimal SSP additive methods achieve a monotonicity-preserving step-size restriction no better than that of the corresponding non-additive SSP linear multistep methods. Furthermore, we develop the first SSP linear multistep methods of order two and three with variable step size, and study their optimality. We describe an optimal step-size strategy and demonstrate the effectiveness of these methods on various one- and multi-dimensional problems. Finally, we establish necessary conditions
Analytical method for thermal stress analysis of plasma facing materials
International Nuclear Information System (INIS)
You, J.H.; Bolt, H.
2001-01-01
The thermo-mechanical response of plasma facing materials (PFMs) to heat loads from the fusion plasma is one of the crucial issues in fusion technology. In this work, a fully analytical description of the thermal stress distribution in armour tiles of plasma facing components is presented which is expected to occur under typical high heat flux (HHF) loads. The method of stress superposition is applied considering the temperature gradient and thermal expansion mismatch. Several combinations of PFMs and heat sink metals are analysed and compared. In the framework of the present theoretical model, plastic flow and the effect of residual stress can be quantitatively assessed. Possible failure features are discussed
Analytical method for thermal stress analysis of plasma facing materials
You, J. H.; Bolt, H.
2001-10-01
The thermo-mechanical response of plasma facing materials (PFMs) to heat loads from the fusion plasma is one of the crucial issues in fusion technology. In this work, a fully analytical description of the thermal stress distribution in armour tiles of plasma facing components is presented which is expected to occur under typical high heat flux (HHF) loads. The method of stress superposition is applied considering the temperature gradient and thermal expansion mismatch. Several combinations of PFMs and heat sink metals are analysed and compared. In the framework of the present theoretical model, plastic flow and the effect of residual stress can be quantitatively assessed. Possible failure features are discussed.
Thermally stable surfactants and compositions and methods of use thereof
Chaiko, David J [Woodridge, IL
2008-09-02
There are provided novel thermally stable surfactants for use with fillers in the preparation of polymer composites and nanocomposites. Typically, surfactants of the invention are urethanes, ureas or esters of thiocarbamic acid having a hydrocarbyl group of from 10 to 50 carbons and optionally including an ionizable or charged group (e.g., carboxyl group or quaternary amine). Thus, there are provided surfactants having Formula I: ##STR00001## wherein the variables are as defined herein. Further provided are methods of making thermally stable surfactants and compositions, including composites and nanocomposites, using fillers coated with the surfactants.
Ion-step method for surface potential sensing of silicon nanowires
Chen, S.; van Nieuwkasteele, Jan William; van den Berg, Albert; Eijkel, Jan C.T.
2016-01-01
This paper presents a novel stimulus-response method for surface potential sensing of silicon nanowire (Si NW) field-effect transistors. When an "ion-step" from low to high ionic strength is given as a stimulus to the gate oxide surface, an increase of double layer capacitance is therefore expected.
A two-step iterative method and its acceleration for outer inverses
Indian Academy of Sciences (India)
A two-step iterative method and its accelerated version for approximating outer inverse A2 T,S of an arbitrary matrix A are proposed. A convergence theorem for its existence is established. The rigorous error bounds are derived. Numerical experiments involving singular square, rectangular, random matrices and a sparse ...
short communication a convenient and efficient one-step method for ...
African Journals Online (AJOL)
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study and possible applications are limited by their complicated synthetic procedure. The original method [9] requires nine consecutive steps to produce I with total yield of about 7% to obtain ligand II. In 1998 Busch and coworkers provided a simple route to the synthesis of ligand II by a Mannich reaction [16]. Although, this ...
International Nuclear Information System (INIS)
Hojabry, A.; Rezainik, Y.; Abdoljavad, N.; Moghimi, N.; Shakib, M.
2007-01-01
In this paper, Tin oxide (SnO 2 ) nano crystals have been synthesized by one-step solid-state chemical reactions method. In the first step, the powder of SnCl 4 . 5H 2 O was mixed with MgCl 2 and Mg(OH) 2 with a weight ratio of Sn to Mg (2:1) in the air atmosphere at room, and then annealed at 200 d egree C , 400 d egree C and 600 d egree C in air for 4 h to give different size of nanoparticles. This method is a simple, efficient and economic preparation for SnO 2 nanoparticles with adjustable grain sizes in the range of 7-32 nm in high yield. The microstructure and morphology of SnO 2 nanoparticles have been studied by X-ray diffraction (XRD), scanning electron microscopy and thermal analysis (thermogravimetric analysis -differential thermal analysis).
Rationalization of thermal injury quantification methods: application to skin burns.
Viglianti, Benjamin L; Dewhirst, Mark W; Abraham, John P; Gorman, John M; Sparrow, Eph M
2014-08-01
Classification of thermal injury is typically accomplished either through the use of an equivalent dosimetry method (equivalent minutes at 43 °C, CEM43 °C) or through a thermal-injury-damage metric (the Arrhenius method). For lower-temperature levels, the equivalent dosimetry approach is typically employed while higher-temperature applications are most often categorized by injury-damage calculations. The two methods derive from common thermodynamic/physical chemistry origins. To facilitate the development of the interrelationships between the two metrics, application is made to the case of skin burns. This thermal insult has been quantified by numerical simulation, and the extracted time-temperature results served for the evaluation of the respective characterizations. The simulations were performed for skin-surface exposure temperatures ranging from 60 to 90 °C, where each surface temperature was held constant for durations extending from 10 to 110 s. It was demonstrated that values of CEM43 at the basal layer of the skin were highly correlated with the depth of injury calculated from a thermal injury integral. Local values of CEM43 were connected to the local cell survival rate, and a correlating equation was developed relating CEM43 with the decrease in cell survival from 90% to 10%. Finally, it was shown that the cell survival/CEM43 relationship for the cases investigated here most closely aligns with isothermal exposure of tissue to temperatures of ~50 °C. Copyright © 2013 Elsevier Ltd and ISBI. All rights reserved.
Multi-off-grid methods in multi-step integration of ordinary differential equations
Beaudet, P. R.
1974-01-01
Description of methods of solving first- and second-order systems of differential equations in which all derivatives are evaluated at off-grid locations in order to circumvent the Dahlquist stability limitation on the order of on-grid methods. The proposed multi-off-grid methods require off-grid state predictors for the evaluation of the n derivatives at each step. Progressing forward in time, the off-grid states are predicted using a linear combination of back on-grid state values and off-grid derivative evaluations. A comparison is made between the proposed multi-off-grid methods and the corresponding Adams and Cowell on-grid integration techniques in integrating systems of ordinary differential equations, showing a significant reduction in the error at larger step sizes in the case of the multi-off-grid integrator.
Determination of reactor thermal power using a more accurate method
International Nuclear Information System (INIS)
Papuga, J.; Madron, F.; Pliska, J.
2005-01-01
Reactor thermal power is an important operational parameter in many respects such as nuclear safety, reactor physics or evaluation of turbine thermal performance. Thermal power of a pressurized water reactor is determined on the basis of the steam generator thermal balance. The balance can be made in several variants differing from one another by the selection of different measuring circuits whose data are used in the balancing. In principle, no one such variant gives the true value of the thermal power. Among the variant values, the one nearest to the unknown true value of reactor thermal power is probably the value calculated with the lowest uncertainty. The determination of such uncertainty is not easy and its value can make even several percent, which has significant economic consequences. This paper presents the method of data reconciliation and its application to the data of the third of Dukovany NPP. The data reconciliation method allows to exploit all the information which process data contain. It is based on the statistical adjustment of the redundant data in such a way that the adjusted data obey generally valid laws of nature (e.g. conservation laws). Mass and energy balances based on the data not yet reconciled do not obey those laws because of measurement errors. For data reconciliation in Dukovany, a detailed model of mass and energy flows describing the 3rd unit from steam generators to alternator and condenser was set up. Laws of mass and energy conservation and phase equilibrium in water-steam systems are thus fulfilled. Moreover, the user can model momentum balances in pipelines and create other equations, which are respected during calculation. The data reconciliation is done regularly for hourly averages (Authors)
Momentum integral network method for thermal-hydraulic transient analysis
International Nuclear Information System (INIS)
Van Tuyle, G.J.
1983-01-01
A new momentum integral network method has been developed, and tested in the MINET computer code. The method was developed in order to facilitate the transient analysis of complex fluid flow and heat transfer networks, such as those found in the balance of plant of power generating facilities. The method employed in the MINET code is a major extension of a momentum integral method reported by Meyer. Meyer integrated the momentum equation over several linked nodes, called a segment, and used a segment average pressure, evaluated from the pressures at both ends. Nodal mass and energy conservation determined nodal flows and enthalpies, accounting for fluid compression and thermal expansion
Analysis of the Finite Precision s-Step Biconjugate Gradient Method
2014-03-13
industrial sponsors and affiliates Intel, Google, Nokia, NVIDIA, Oracle, and Samsung . Any opinions, findings, conclusions, or recommendations in this...multiprocessors with memory hierarchy, Parallel Comput., 11 (1989), pp. 37–53. [5] , s-step iterative methods for symmetric linear systems, J. Comput. Appl ...University Press, 2012. [10] A. Greenbaum, Estimating the attainable accuracy of recursively computed residual methods, SIAM J. Matrix Anal. Appl ., 18
Brinkmann, Ralf Peter
2015-12-01
The electric field in radio-frequency driven capacitively coupled plasmas (RF-CCP) is studied, taking thermal (finite electron temperature) and dynamic (finite electron mass) effects into account. Two dimensionless numbers are introduced, the ratios ε ={λ\\text{D}}/l of the electron Debye length {λ\\text{D}} to the minimum plasma gradient length l (typically the sheath thickness) and η ={ω\\text{RF}}/{ω\\text{pe}} of the RF frequency {ω\\text{RF}} to the electron plasma frequency {ω\\text{pe}} . Assuming both numbers small but finite, an asymptotic expansion of an electron fluid model is carried out up to quadratic order inclusively. An expression for the electric field is obtained which yields (i) the space charge field in the sheath, (ii) the generalized Ohmic and ambipolar field in the plasma, and (iii) a smooth interpolation for the transition in between. The new expression is a direct generalization of the Advanced Algebraic Approximation (AAA) proposed by the same author (2009 J. Phys. D: Appl. Phys. 42 194009), which can be recovered for η \\to 0 , and of the established Step Model (SM) by Godyak (1976 Sov. J. Plasma Phys. 2 78), which corresponds to the simultaneous limits η \\to 0 , ε \\to 0 . A comparison of the hereby proposed Smooth Step Model (SSM) with a numerical solution of the full dynamic problem proves very satisfactory.
A variable step method for the numerical integration of the one-dimensional Schroedinger equation
International Nuclear Information System (INIS)
Raptis, A.D.; Cash, J.R.
1985-01-01
Most numerical methods which have been proposed for the approximate integration of the one-dimensional Schroedinger equation use a fixed step length of integration. Such an approach can of course result in gross inefficiency since the small step length which must normally be used in the initial part of the range of integration to obtain the desired accuracy must then be used throughout the integration. In this paper we consider the method of embedding, which is widely used with explicit Runge-Kutta methods for the solution of first order initial value problems, for use with the special formulae used to integrate the Schroedinger equation. By adopting this technique we have available at each step an estimate of the local truncation error and this estimate can be used to automatically control the step length of integration. Also considered is the problem of estimating the global truncation error at the end of the range of integration. The power of the approaches considered is illustrated by means of some numerical examples. (orig.)
A Dimensionality Reduction-Based Multi-Step Clustering Method for Robust Vessel Trajectory Analysis
Directory of Open Access Journals (Sweden)
Huanhuan Li
2017-08-01
Full Text Available The Shipboard Automatic Identification System (AIS is crucial for navigation safety and maritime surveillance, data mining and pattern analysis of AIS information have attracted considerable attention in terms of both basic research and practical applications. Clustering of spatio-temporal AIS trajectories can be used to identify abnormal patterns and mine customary route data for transportation safety. Thus, the capacities of navigation safety and maritime traffic monitoring could be enhanced correspondingly. However, trajectory clustering is often sensitive to undesirable outliers and is essentially more complex compared with traditional point clustering. To overcome this limitation, a multi-step trajectory clustering method is proposed in this paper for robust AIS trajectory clustering. In particular, the Dynamic Time Warping (DTW, a similarity measurement method, is introduced in the first step to measure the distances between different trajectories. The calculated distances, inversely proportional to the similarities, constitute a distance matrix in the second step. Furthermore, as a widely-used dimensional reduction method, Principal Component Analysis (PCA is exploited to decompose the obtained distance matrix. In particular, the top k principal components with above 95% accumulative contribution rate are extracted by PCA, and the number of the centers k is chosen. The k centers are found by the improved center automatically selection algorithm. In the last step, the improved center clustering algorithm with k clusters is implemented on the distance matrix to achieve the final AIS trajectory clustering results. In order to improve the accuracy of the proposed multi-step clustering algorithm, an automatic algorithm for choosing the k clusters is developed according to the similarity distance. Numerous experiments on realistic AIS trajectory datasets in the bridge area waterway and Mississippi River have been implemented to compare our
A Dimensionality Reduction-Based Multi-Step Clustering Method for Robust Vessel Trajectory Analysis.
Li, Huanhuan; Liu, Jingxian; Liu, Ryan Wen; Xiong, Naixue; Wu, Kefeng; Kim, Tai-Hoon
2017-08-04
The Shipboard Automatic Identification System (AIS) is crucial for navigation safety and maritime surveillance, data mining and pattern analysis of AIS information have attracted considerable attention in terms of both basic research and practical applications. Clustering of spatio-temporal AIS trajectories can be used to identify abnormal patterns and mine customary route data for transportation safety. Thus, the capacities of navigation safety and maritime traffic monitoring could be enhanced correspondingly. However, trajectory clustering is often sensitive to undesirable outliers and is essentially more complex compared with traditional point clustering. To overcome this limitation, a multi-step trajectory clustering method is proposed in this paper for robust AIS trajectory clustering. In particular, the Dynamic Time Warping (DTW), a similarity measurement method, is introduced in the first step to measure the distances between different trajectories. The calculated distances, inversely proportional to the similarities, constitute a distance matrix in the second step. Furthermore, as a widely-used dimensional reduction method, Principal Component Analysis (PCA) is exploited to decompose the obtained distance matrix. In particular, the top k principal components with above 95% accumulative contribution rate are extracted by PCA, and the number of the centers k is chosen. The k centers are found by the improved center automatically selection algorithm. In the last step, the improved center clustering algorithm with k clusters is implemented on the distance matrix to achieve the final AIS trajectory clustering results. In order to improve the accuracy of the proposed multi-step clustering algorithm, an automatic algorithm for choosing the k clusters is developed according to the similarity distance. Numerous experiments on realistic AIS trajectory datasets in the bridge area waterway and Mississippi River have been implemented to compare our proposed method with
A new method of measuring the thermal flow
Directory of Open Access Journals (Sweden)
Grexová Slávka
2001-03-01
Full Text Available The subject of this article is the measurement of thermal flow under laboratory conditions. We can define thermal flow as the amount of heat transmitted through the surface of rock over a certain period of time.According to the Atlas of Geothermal Energy the thermal flow ranges from 40 to 120 mW/m2; it is not possible to measure directly on the surface of the rock. The conventional method of measurement is the use of separation bar thermic conduction measurement system or to measure the temperature of the rock in two different places at selected underground depth intervals.The method of measurement suggested by us combines these two techniques. The measurement is based on a sample of processed store from the Slovak Academy of Science. This sample represents the rock massiv:The complex model includes:- a heating system to imitate the thermal flow,- an isolation box to maintain stable conditions,- temperature stabilizing components (thermostat, bulbs, electric conductors,- a heat accumulator including a temperature sensor.A special computer program to measure the thermal flow was created using the Borland Delphi 3.0 programming language. The role of the program is to process extensive data quickly. The results of the measured temperatures and modelled thermal flow are displayed graphically in this article. As seen from the graph, the course of measurement thermal flow is linear. In our geographical location this value is cca 120 m W.m-2. This value proves, that at the projection physical model we are approximating to the reality in areas of sensitive elements. Another fact is that Joule heat which rose into a heater system of transformer straps under muster would thermal flow 2,25 W.m-2. From the present results that by follow the sensitivity measurement scanners it is needed to measure a minimum threefold during a longer time or to improve the sensitivity measurement chains.These measurements and analyses are not sufficient to make a final
Production and characterization of TI/PbO2 electrodes by a thermal-electrochemical method
Directory of Open Access Journals (Sweden)
Laurindo Edison A.
2000-01-01
Full Text Available Looking for electrodes with a high overpotential for the oxygen evolution reaction (OER, useful for the oxidation of organic pollutants, Ti/PbO2 electrodes were prepared by a thermal-electrochemical method and their performance was compared with that of electrodeposited electrodes. The open-circuit potential for these electrodes in 0.5 mol L-1 H2SO4 presented quite stable similar values. X-ray diffraction analyses showed the thermal-electrochemical oxide to be a mixture of ort-PbO, tetr-PbO and ort-PbO2. On the other hand, the electrodes obtained by electrodeposition were in the tetr-PbO2 form. Analyses by scanning electron microscopy showed that the basic morphology of the thermal-electrochemical PbO2 is determined in the thermal step, being quite distinct from that of the electrodeposited electrodes. Polarization curves in 0.5 mol L-1 H2SO4 showed that in the case of the thermal-electrochemical PbO2 electrodes the OER was shifted to more positive potentials. However, the values of the Tafel slopes, quite high, indicate that passivating films were possibly formed on the Ti substrates, which could eventually explain the somewhat low current values for OER.
Method for Measuring Thermal Conductivity of Small Samples Having Very Low Thermal Conductivity
Miller, Robert A.; Kuczmarski, Maria a.
2009-01-01
This paper describes the development of a hot plate method capable of using air as a standard reference material for the steady-state measurement of the thermal conductivity of very small test samples having thermal conductivity on the order of air. As with other approaches, care is taken to ensure that the heat flow through the test sample is essentially one-dimensional. However, unlike other approaches, no attempt is made to use heated guards to block the flow of heat from the hot plate to the surroundings. It is argued that since large correction factors must be applied to account for guard imperfections when sample dimensions are small, it may be preferable to simply measure and correct for the heat that flows from the heater disc to directions other than into the sample. Experimental measurements taken in a prototype apparatus, combined with extensive computational modeling of the heat transfer in the apparatus, show that sufficiently accurate measurements can be obtained to allow determination of the thermal conductivity of low thermal conductivity materials. Suggestions are made for further improvements in the method based on results from regression analyses of the generated data.
Phase-contrast diffuse optical tomography for in vivo breast imaging: a two-step method
International Nuclear Information System (INIS)
Jiang Ruixin; Liang Xiaoping; Zhang Qizhi; Grobmyer, Stephen; Fajardo, Laurie L.; Jiang Huabei
2009-01-01
We present a two-step reconstruction method that can qualitatively and quantitatively improve the reconstruction of tissue refractive index (RI) distribution by phase-contrast diffuse optical tomography (PCDOT). In this two-step method, we first recover the distribution of tissue absorption and scattering coefficients by conventional diffuse optical tomography to obtain the geometrical information of lesions, allowing the incorporation of geometrical information as a priori in the PCDOT reconstruction using a locally refined mesh. The method is validated by a series of phantom experiments and evaluated using in vivo data from 42 human subjects. The results demonstrate clear contrast of RI between the lesion and the surroundings, making the image interpretation straightforward. The sensitivity and specificity from these 42 cases are both 81% when RI is used as an imaging parameter for distinguishing between malignant and benign lesions.
A Method of MPPT Control Based on Power Variable Step-size in Photovoltaic Converter System
Directory of Open Access Journals (Sweden)
Xu Hui-xiang
2016-01-01
Full Text Available Since the disadvantage of traditional MPPT algorithms of variable step-size, proposed power tracking based on variable step-size with the advantage method of the constant-voltage and the perturb-observe (P&O[1-3]. The control strategy modify the problem of voltage fluctuation caused by perturb-observe method, at the same time, introducing the advantage of constant-voltage method and simplify the circuit topology. With the theoretical derivation, control the output power of photovoltaic modules to change the duty cycle of main switch. Achieve the maximum power stabilization output, reduce the volatility of energy loss effectively, and improve the inversion efficiency[3,4]. Given the result of experimental test based theoretical derivation and the curve of MPPT when the prototype work.
Evaluation of lung and chest wall mechanics during anaesthesia using the PEEP-step method.
Persson, P; Stenqvist, O; Lundin, S
2018-04-01
Postoperative pulmonary complications are common. Between patients there are differences in lung and chest wall mechanics. Individualised mechanical ventilation based on measurement of transpulmonary pressures would be a step forward. A previously described method evaluates lung and chest wall mechanics from a change of ΔPEEP and calculation of change in end-expiratory lung volume (ΔEELV). The aim of the present study was to validate this PEEP-step method (PSM) during general anaesthesia by comparing it with the conventional method using oesophageal pressure (PES) measurements. In 24 lung healthy subjects (BMI 18.5-32), three different sizes of PEEP steps were performed during general anaesthesia and ΔEELVs were calculated. Transpulmonary driving pressure (ΔPL) for a tidal volume equal to each ΔEELV was measured using PES measurements and compared to ΔPEEP with limits of agreement and intraclass correlation coefficients (ICC). ΔPL calculated with both methods was compared with a Bland-Altman plot. Mean differences between ΔPEEP and ΔPL were mechanical properties among the lung healthy patients stresses the need for individualised ventilator settings based on measurements of lung and chest wall mechanics. The agreement between ΔPLs measured by the two methods during general anaesthesia suggests the use of the non-invasive PSM in this patient population. NCT 02830516. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Hussein, Mahir S. [DCTA, Instituto Tecnologico de Aeronautica, Sao Jose dos Campos, SP (Brazil); Universidade de Sao Paulo, Instituto de Estudos Avancados, C. P. 72012, Sao Paulo, SP (Brazil); Universidade de Sao Paulo, Instituto de Fisica, C. P. 66318, Sao Paulo, SP (Brazil)
2017-05-15
In this Letter I argue that the Surrogate Method, used to extract the fast neutron capture cross section on actinide target nuclei, which has important practical application for the next generation of breeder reactors, and the Trojan Horse Method employed to extract reactions of importance to nuclear astrophysics, have a common foundation, the Inclusive Non-Elastic Breakup (INEB) Theory. Whereas the Surrogate Method relies on the premise that the extracted neutron cross section in a (d, p) reaction is predominantly a compound-nucleus one, the Trojan Horse Method assumes a predominantly direct process for the secondary reaction induced by the surrogate fragment. In general, both methods contain both direct and compound contributions, and I show how these seemingly distinct methods are in fact the same but at different energies and different kinematic regions. The unifying theory is the rather well developed INEB theory. (orig.)
Stability of one-step methods in transient nonlinear heat conduction
International Nuclear Information System (INIS)
Hughes, J.R.
1977-01-01
The purpose of the present work is to ascertain practical stability conditions for one-step methods commonly used in transient nonlinear heat conduction analyses. In this paper the concepts of stability, appropriate to the nonlinear problem, are thoroughly discussed. They of course reduce to the usual stability critierion for the linear, constant coefficient case. However, for nonlinear problems there are differences and theses ideas are of key importance in obtaining practical stability conditions. Of particular importance is a recent result which indicates that, in a sense, the trapezoidal and midpoint families are equivalent. Thus, stability results for one family may be translated into a result for the other. The main results obtained are: The stability behaviour of the explicit Euler method in the nonlinear regime is analogous to that for linear problems. In particular, an a priori step size restriction may be determined for each time step. The precise time step restriction on implicit conditionally stable members of the trapezoidal and midpoint families is shown not to be determinable a priori. Of considerable practical significance, unconditionally stable members of the trapezoidal and midpoint families are identified. All notions of stability employed are motivated and defined, and their interpretations in practical computing are indicated. (Auth.)
International Nuclear Information System (INIS)
Lu Yanlin; Zhou Xiao; Qu Jiadi; Dou Yikang; He Yinbiao
2005-01-01
An efficient scheme, 3-D thermal weight function (TWF) method, and a novel numerical technique, multiple virtual crack extension (MVCE) technique, were developed for determination of histories of transient stress intensity factor (SIF) distributions along 3-D crack fronts of a body subjected to thermal shock. The TWF is a universal function, which is dependent only on the crack configuration and body geometry. TWF is independent of time during thermal shock, so the whole history of transient SIF distributions along crack fronts can be directly calculated through integration of the products of TWF and transient temperatures and temperature gradients. The repeated determinations of the distributions of stresses (or displacements) fields for individual time instants are thus avoided in the TWF method. An expression of the basic equation for the 3-D universal weight function method for Mode I in an isotropic elastic body is derived. This equation can also be derived from Bueckner-Rice's 3-D WF formulations in the framework of transformation strain. It can be understood from this equation that the so-called thermal WF is in fact coincident with the mechanical WF except for some constants of elasticity. The details and formulations of the MVCE technique are given for elliptical cracks. The MVCE technique possesses several advantages. The specially selected linearly independent VCE modes can directly be used as shape functions for the interpolation of unknown SIFs. As a result, the coefficient matrix of the final system of equations in the MVCE method is a triple-diagonal matrix and the values of the coefficients on the main diagonal are large. The system of equations has good numerical properties. The number of linearly independent VCE modes that can be introduced in a problem is unlimited. Complex situations in which the SIFs vary dramatically along crack fronts can be numerically well simulated by the MVCE technique. An integrated system of programs for solving the
Flow Over Backward Facing Step with Inclined Wall Solved by Finite Volume and Finite Element Method
Louda, Petr; Sváček, Petr; Kozel, Karel; Příhoda, Jaromír
2010-09-01
The work deals with numerical solution of 2D incompressible flow over backward facing step. The inclination angles of the upper wall of the channel were chosen as in measurements by Driver and Seegmiller [1]. Two numerical methods are considered. One is finite volume method, the other one is finite element method. Turbulence is modeled using two-equation turbulence models of k-ω type. The influence of outlet boundary condition is discussed and do-nothing-like condition found suitable also for finite volume method. The comparison of both methods is presented for laminar as well as turbulent cases, including experimental results. The differences of the results are studied using one turbulence model and both numerical methods or one method and more turbulence models. It is found that sensitivity of the computation to these circumstances increases for higher inclination angles (diffuser flow).
Thermal disadvantage factor calculation by the multiregion collision probability method
International Nuclear Information System (INIS)
Ozgener, B.; Ozgener, H.A.
2004-01-01
A multi-region collision probability formulation that is capable of applying white boundary condition directly is presented and applied to thermal neutron transport problems. The disadvantage factors computed are compared with their counterparts calculated by S N methods with both direct and indirect application of white boundary condition. The results of the ABH and collision probability method with indirect application of white boundary condition are also considered and comparisons with benchmark Monte Carlo results are carried out. The studies show that the proposed formulation is capable of calculating thermal disadvantage factor with sufficient accuracy without resorting to the fictitious scattering outer shell approximation associated with the indirect application of the white boundary condition in collision probability solutions
Dümichen, Erik; Eisentraut, Paul; Bannick, Claus Gerhard; Barthel, Anne-Kathrin; Senz, Rainer; Braun, Ulrike
2017-05-01
In order to determine the relevance of microplastic particles in various environmental media, comprehensive investigations are needed. However, no analytical method exists for fast identification and quantification. At present, optical spectroscopy methods like IR and RAMAN imaging are used. Due to their time consuming procedures and uncertain extrapolation, reliable monitoring is difficult. For analyzing polymers Py-GC-MS is a standard method. However, due to a limited sample amount of about 0.5 mg it is not suited for analysis of complex sample mixtures like environmental samples. Therefore, we developed a new thermoanalytical method as a first step for identifying microplastics in environmental samples. A sample amount of about 20 mg, which assures the homogeneity of the sample, is subjected to complete thermal decomposition. The specific degradation products of the respective polymer are adsorbed on a solid-phase adsorber and subsequently analyzed by thermal desorption gas chromatography mass spectrometry. For certain identification, the specific degradation products for the respective polymer were selected first. Afterwards real environmental samples from the aquatic (three different rivers) and the terrestrial (bio gas plant) systems were screened for microplastics. Mainly polypropylene (PP), polyethylene (PE) and polystyrene (PS) were identified for the samples from the bio gas plant and PE and PS from the rivers. However, this was only the first step and quantification measurements will follow. Copyright © 2017 Elsevier Ltd. All rights reserved.
A single-step method for rapid extraction of total lipids from green microalgae.
Directory of Open Access Journals (Sweden)
Martin Axelsson
Full Text Available Microalgae produce a wide range of lipid compounds of potential commercial interest. Total lipid extraction performed by conventional extraction methods, relying on the chloroform-methanol solvent system are too laborious and time consuming for screening large numbers of samples. In this study, three previous extraction methods devised by Folch et al. (1957, Bligh and Dyer (1959 and Selstam and Öquist (1985 were compared and a faster single-step procedure was developed for extraction of total lipids from green microalgae. In the single-step procedure, 8 ml of a 2∶1 chloroform-methanol (v/v mixture was added to fresh or frozen microalgal paste or pulverized dry algal biomass contained in a glass centrifuge tube. The biomass was manually suspended by vigorously shaking the tube for a few seconds and 2 ml of a 0.73% NaCl water solution was added. Phase separation was facilitated by 2 min of centrifugation at 350 g and the lower phase was recovered for analysis. An uncharacterized microalgal polyculture and the green microalgae Scenedesmus dimorphus, Selenastrum minutum, and Chlorella protothecoides were subjected to the different extraction methods and various techniques of biomass homogenization. The less labour intensive single-step procedure presented here allowed simultaneous recovery of total lipid extracts from multiple samples of green microalgae with quantitative yields and fatty acid profiles comparable to those of the previous methods. While the single-step procedure is highly correlated in lipid extractability (r² = 0.985 to the previous method of Folch et al. (1957, it allowed at least five times higher sample throughput.
Thermal properties and water repellency of cotton fabric prepared through sol-gel method
Directory of Open Access Journals (Sweden)
Gu Jia-Li
2016-01-01
Full Text Available Cotton fabrics were treated by one-step sol-gel method. The pure silica hydrosol and phosphorus-doped hydrosol were prepared with the addition of a hydrophobic hexadecyltrimethoxysilane to decrease the surface energy of cotton fabric. The thermal properties and water repellency of treated cotton fabric were characterized by thermo-gravimetric analysis, micro combustion, limiting oxygen index, and contact angle measurement. The results showed that cotton fabric treated by phosphorus-doped silica hydrosol had excellent flame retardance, and the water repellence was apparently improved with the addition of hexadecyltrimethoxysilane.
Canine distemper virus detection by different methods of One-Step RT-qPCR
Directory of Open Access Journals (Sweden)
Claudia de Camargo Tozato
2016-01-01
Full Text Available ABSTRACT: Three commercial kits of One-Step RT-qPCR were evaluated for the molecular diagnosis of Canine Distemper Virus. Using the kit that showed better performance, two systems of Real-time RT-PCR (RT-qPCR assays were tested and compared for analytical sensitivity to Canine Distemper Virus RNA detection: a One-Step RT-qPCR (system A and a One-Step RT-qPCR combined with NESTED-qPCR (system B. Limits of detection for both systems were determined using a serial dilution of Canine Distemper Virus synthetic RNA or a positive urine sample. In addition, the same urine sample was tested using samples with prior centrifugation or ultracentrifugation. Commercial kits of One-Step RT-qPCR assays detected canine distemper virus RNA in 10 (100% urine samples from symptomatic animals tested. The One-Step RT-qPCR kit that showed better results was used to evaluate the analytical sensitivity of the A and B systems. Limit of detection using synthetic RNA for the system A was 11 RNA copies µL-1 and 110 RNA copies µl-1 for first round System B. The second round of the NESTED-qPCR for System B had a limit of detection of 11 copies µl-1. Relationship between Ct values and RNA concentration was linear. The RNA extracted from the urine dilutions was detected in dilutions of 10-3 and10-2 by System A and B respectively. Urine centrifugation increased the analytical sensitivity of the test and proved to be useful for routine diagnostics. The One-Step RT-qPCR is a fast, sensitive and speciﬁc method for canine distemper routine diagnosis and research projects that require sensitive and quantitative methodology.
International Nuclear Information System (INIS)
Kim, Byung-Jae; Hwang, Ya-Hsi; Ahn, Shihyun; Zhu, Weidi; Dong, Chen; Lu, Liu; Ren, Fan; Holzworth, M. R.; Jones, Kevin S.; Pearton, Stephen J.; Smith, David J.; Kim, Jihyun; Zhang, Ming-Lan
2015-01-01
The recovery effects of thermal annealing on dc and rf performance of off-state step-stressed AlGaN/GaN high electron mobility transistors were investigated. After stress, reverse gate leakage current and sub-threshold swing increased and drain current on-off ratio decreased. However, these degradations were completely recovered after thermal annealing at 450 °C for 10 mins for devices stressed either once or twice. The trap densities, which were estimated by temperature-dependent drain-current sub-threshold swing measurements, increased after off-state step-stress and were reduced after subsequent thermal annealing. In addition, the small signal rf characteristics of stressed devices were completely recovered after thermal annealing
2015-09-01
E PIEKOS 2 ADVANCED THERMAL (PDF) BATTERIES , INC D BRISCOE G CHAGNON 3 EAGLE PICHER (PDF) TECHNOLOGIES, LLC C LAMB J...Thin-Film Thermal Batteries by Frank C Krieger and Michael S Ding Approved for public release; distribution unlimited...Laboratory Gas Control and Thermal Modeling Methods for Pressed Pellet and Fast Rise Thin-Film Thermal Batteries by Frank C Krieger and Michael S
Methods of evaluation of thermal tolerance of cyclic sports athletes
Directory of Open Access Journals (Sweden)
Kish А.А.
2017-12-01
Full Text Available The purpose of the study is investigation of thermal stability in athletes of cyclic sports and assessment of its influence on physical working capacity under hyperthermia. Material and methods. 15 male athletes of cyclic sports who had the senior degree as minimum were included in the study Middle age 24,2±1,1 years. Work was performed in the climatic camera of the Center of sports medicine and rehabilitation in several stages, on each of which assessment of physical working capacity and a thermal condition of athletes was carried out. Results. In the real work the burdening action of the heating climate on indicators of physical working capacity and a thermal condition of athletes of cyclic sports is shown; the operating ranges of high temperatures are determined. Conclusion. The data obtained by means of the offered technique, confirm importance of definition of individual thresholds of shipping of a thermal state at athletes and the burdening action of a heat on their physical working capacity.
Nanda, D; Varshney, P; Satapathy, M; Mohapatra, S S; Bhushan, B; Kumar, A
2017-12-01
The development of self-cleaning and anti-fogging durable superliquiphobic coatings for aluminum surfaces has raised tremendous interest in materials science. In this study, a superliquiphobic coating is fabricated on an aluminum surface by a single-step dip-coating method using 1H,1H,2H,2H-Perfluorooctyltrichlorosilane-modified SiO 2 nanoparticles. The successful implementation of the aforesaid coating in different applications requires extensive investigations of its characteristics and stability. To understand the properties of the coating, surface morphology, contact angle, self-cleaning, anti-fogging, and water repellency were investigated under perturbation conditions. Additionally, the dynamics of water and oil on the coated sample also were studied. Furthermore, the durability of the coating also was examined by performing thermal, chemical, and mechanical stability tests. It was found that the coating is superliquiphobic for water, ethylene glycol, glycerol and hexadecane, and shows thermal, chemical, and mechanical stability. Further, it exhibits self-cleaning and anti-fogging properties. This approach can be applied to any size and shape aluminum surface; thus, it has great industrial applications. Copyright © 2017 Elsevier Inc. All rights reserved.
Acceleration of step and linear discontinuous schemes for the method of characteristics in DRAGON5
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Alain Hébert
2017-09-01
Full Text Available The applicability of the algebraic collapsing acceleration (ACA technique to the method of characteristics (MOC in cases with scattering anisotropy and/or linear sources was investigated. Previously, the ACA was proven successful in cases with isotropic scattering and uniform (step sources. A presentation is first made of the MOC implementation, available in the DRAGON5 code. Two categories of schemes are available for integrating the propagation equations: (1 the first category is based on exact integration and leads to the classical step characteristics (SC and linear discontinuous characteristics (LDC schemes and (2 the second category leads to diamond differencing schemes of various orders in space. The acceleration of these MOC schemes using a combination of the generalized minimal residual [GMRES(m] method preconditioned with the ACA technique was focused on. Numerical results are provided for a two-dimensional (2D eight-symmetry pressurized water reactor (PWR assembly mockup in the context of the DRAGON5 code.
Investigating the Effectiveness of Teaching Methods Based on a Four-Step Constructivist Strategy
Çalik, Muammer; Ayas, Alipaşa; Coll, Richard K.
2010-02-01
This paper reports on an investigation of the effectiveness an intervention using several different methods for teaching solution chemistry. The teaching strategy comprised a four-step approach derived from a constructivist view of learning. A sample consisting of 44 students (18 boys and 26 girls) was selected purposively from two different Grade 9 classes in the city of Trabzon, Turkey. Data collection employed a purpose-designed `solution chemistry concept test', consisting of 17 items, with the quantitative data from the survey supported by qualitative interview data. The findings suggest that using different methods embedded within the four-step constructivist-based teaching strategy enables students to refute some alternative conceptions, but does not completely eliminate student alternative conceptions for solution chemistry.
Numerical methods for calculating thermal residual stresses and hydrogen diffusion
International Nuclear Information System (INIS)
Leblond, J.B.; Devaux, J.; Dubois, D.
1983-01-01
Thermal residual stresses and hydrogen concentrations are two major factors intervening in cracking phenomena. These parameters were numerically calculated by a computer programme (TITUS) using the FEM, during the deposition of a stainless clad on a low-alloy plate. The calculation was performed with a 2-dimensional option in four successive steps: thermal transient calculation, metallurgical transient calculation (determination of the metallurgical phase proportions), elastic-plastic transient (plain strain conditions), hydrogen diffusion transient. Temperature and phase dependence of hydrogen diffusion coefficient and solubility constant. The following results were obtained: thermal calculations are very consistent with experiments at higher temperatures (due to the introduction of fusion and solidification latent heats); the consistency is not as good (by 70 degrees) for lower temperatures (below 650 degrees C); this was attributed to the non-introduction of gamma-alpha transformation latent heat. The metallurgical phase calculation indicates that the heat affected zone is almost entirely transformed into bainite after cooling down (the martensite proportion does not exceed 5%). The elastic-plastic calculations indicate that the stresses in the heat affected zone are compressive or slightly tensile; on the other hand, higher tensile stresses develop on the boundary of the heat affected zone. The transformation plasticity has a definite influence on the final stress level. The return of hydrogen to the clad during the bainitic transformation is but an incomplete phenomenon and the hydrogen concentration in the heat affected zone after cooling down to room temperature is therefore sufficient to cause cold cracking (if no heat treatment is applied). Heat treatments are efficient in lowering the hydrogen concentration. These results enable us to draw preliminary conclusions on practical means to avoid cracking. (orig.)
Sohrabi, Salman; Liu, Yaling
2018-03-01
Pseudopotential lattice Boltzmann methods (LBMs) can simulate a phase transition in high-density ratio multiphase flow systems. If coupled with thermal LBMs through equation of state, they can be used to study instantaneous phase transition phenomena with a high-temperature gradient where only one set of formulations in an LBM system can handle liquid, vapor, phase transition, and heat transport. However, at lower temperatures an unrealistic spurious current at the interface introduces instability and limits its application in real flow system. In this study, we proposed new modifications to the LBM system to minimize a spurious current which enables us to study nucleation dynamic at room temperature. To demonstrate the capabilities of this approach, the thermal ejection process is modeled as one example of a complex flow system. In an inkjet printer, a thermal pulse instantly heats up the liquid in a microfluidic chamber and nucleates bubble vapor providing the pressure pulse necessary to eject droplets at high speed. Our modified method can present a more realistic model of the explosive vaporization process since it can also capture a high-temperature/density gradient at nucleation region. Thermal inkjet technology has been successfully applied for printing cells, but cells are susceptible to mechanical damage or death as they squeeze out of the nozzle head. To study cell deformation, a spring network model, representing cells, is connected to the LBM through the immersed boundary method. Looking into strain and stress distribution of a cell membrane at its most deformed state, it is found that a high stretching rate effectively increases the rupture tension. In other words, membrane deformation energy is released through creation of multiple smaller nanopores rather than big pores. Overall, concurrently simulating multiphase flow, phase transition, heat transfer, and cell deformation in one unified LB platform, we are able to provide a better insight into the
Combined Effects of Numerical Method Type and Time Step on Water Stressed Actual Crop ET
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B. Ghahraman
2016-02-01
Full Text Available Introduction: Actual crop evapotranspiration (Eta is important in hydrologic modeling and irrigation water management issues. Actual ET depends on an estimation of a water stress index and average soil water at crop root zone, and so depends on a chosen numerical method and adapted time step. During periods with no rainfall and/or irrigation, actual ET can be computed analytically or by using different numerical methods. Overal, there are many factors that influence actual evapotranspiration. These factors are crop potential evapotranspiration, available root zone water content, time step, crop sensitivity, and soil. In this paper different numerical methods are compared for different soil textures and different crops sensitivities. Materials and Methods: During a specific time step with no rainfall or irrigation, change in soil water content would be equal to evapotranspiration, ET. In this approach, however, deep percolation is generally ignored due to deep water table and negligible unsaturated hydraulic conductivity below rooting depth. This differential equation may be solved analytically or numerically considering different algorithms. We adapted four different numerical methods, as explicit, implicit, and modified Euler, midpoint method, and 3-rd order Heun method to approximate the differential equation. Three general soil types of sand, silt, and clay, and three different crop types of sensitive, moderate, and resistant under Nishaboor plain were used. Standard soil fraction depletion (corresponding to ETc=5 mm.d-1, pstd, below which crop faces water stress is adopted for crop sensitivity. Three values for pstd were considered in this study to cover the common crops in the area, including winter wheat and barley, cotton, alfalfa, sugar beet, saffron, among the others. Based on this parameter, three classes for crop sensitivity was considered, sensitive crops with pstd=0.2, moderate crops with pstd=0.5, and resistive crops with pstd=0
Theoretical Modelling Methods for Thermal Management of Batteries
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Bahman Shabani
2015-09-01
Full Text Available The main challenge associated with renewable energy generation is the intermittency of the renewable source of power. Because of this, back-up generation sources fuelled by fossil fuels are required. In stationary applications whether it is a back-up diesel generator or connection to the grid, these systems are yet to be truly emissions-free. One solution to the problem is the utilisation of electrochemical energy storage systems (ESS to store the excess renewable energy and then reusing this energy when the renewable energy source is insufficient to meet the demand. The performance of an ESS amongst other things is affected by the design, materials used and the operating temperature of the system. The operating temperature is critical since operating an ESS at low ambient temperatures affects its capacity and charge acceptance while operating the ESS at high ambient temperatures affects its lifetime and suggests safety risks. Safety risks are magnified in renewable energy storage applications given the scale of the ESS required to meet the energy demand. This necessity has propelled significant effort to model the thermal behaviour of ESS. Understanding and modelling the thermal behaviour of these systems is a crucial consideration before designing an efficient thermal management system that would operate safely and extend the lifetime of the ESS. This is vital in order to eliminate intermittency and add value to renewable sources of power. This paper concentrates on reviewing theoretical approaches used to simulate the operating temperatures of ESS and the subsequent endeavours of modelling thermal management systems for these systems. The intent of this review is to present some of the different methods of modelling the thermal behaviour of ESS highlighting the advantages and disadvantages of each approach.
Growth of zinc oxide nanoflowers by thermal evaporation method
International Nuclear Information System (INIS)
Abdulgafour, H.I.; Hassan, Z.; Al-Hardan, N.; Yam, F.K.
2010-01-01
An alternative method for site-selective growth of ZnO nanostructures that does not use an Au catalyst or a ZnO thin-film seed layer is presented. Well-aligned ZnO nanoflower structure arrays were directly fabricated on silicon substrates through zinc powder evaporation, which uses a simple thermal evaporation method without a catalyst. The collected ZnO nanoflowers were then characterized through X-ray diffraction (XRD) and scanning electron microscopy (SEM). The optical properties of these nanostructured materials are also discussed.
Qian, Cheng; Fan, Jiajie; Fang, Jiayi; Yu, Chaohua; Ren, Yi; Fan, Xuejun; Zhang, Guoqi
2017-10-16
By solving the problem of very long test time on reliability qualification for Light-emitting Diode (LED) products, the accelerated degradation test with a thermal overstress at a proper range is regarded as a promising and effective approach. For a comprehensive survey of the application of step-stress accelerated degradation test (SSADT) in LEDs, the thermal, photometric, and colorimetric properties of two types of LED chip scale packages (CSPs), i.e., 4000 °K and 5000 °K samples each of which was driven by two different levels of currents (i.e., 120 mA and 350 mA, respectively), were investigated under an increasing temperature from 55 °C to 150 °C and a systemic study of driving current effect on the SSADT results were also reported in this paper. During SSADT, junction temperatures of the test samples have a positive relationship with their driving currents. However, the temperature-voltage curve, which represents the thermal resistance property of the test samples, does not show significant variance as long as the driving current is no more than the sample's rated current. But when the test sample is tested under an overdrive current, its temperature-voltage curve is observed as obviously shifted to the left when compared to that before SSADT. Similar overdrive current affected the degradation scenario is also found in the attenuation of Spectral Power Distributions (SPDs) of the test samples. As used in the reliability qualification, SSADT provides explicit scenes on color shift and correlated color temperature (CCT) depreciation of the test samples, but not on lumen maintenance depreciation. It is also proved that the varying rates of the color shift and CCT depreciation failures can be effectively accelerated with an increase of the driving current, for instance, from 120 mA to 350 mA. For these reasons, SSADT is considered as a suitable accelerated test method for qualifying these two failure modes of LED CSPs.
A two-step iterative method for evolving nonlinear acoustic systems to a steady-state
Watson, Willie R.; Myers, Michael K.
1990-01-01
A new approach for evolving two-dimensional nonlinear acoustic systems with flow to a steady state is presented. The approach is a two-step iterative method which is tested on a benchmark acoustic problem for which an exact analytical solution is available. Results are also calculated for a nonlinear acoustic problem for which an exact analytical solution is not known. Results indicate that the two-step method represents a powerful, efficient, and stable method for evolving two-dimensional acoustic systems to a steady state, and that the method is applicable to any number of spatial dimensions and to other hyperbolic systems. It is noted that for the benchmark problem only a single iteration on the method is required when the transient and steady-state field are of the same order of magnitude; however, four iterations are required when the steady-state field is several orders of magnitude smaller than the transient field. This method requires six iterations before achieving a steady state for the nonlinear test problem.
One step linear reconstruction method for continuous wave diffuse optical tomography
Ukhrowiyah, N.; Yasin, M.
2017-09-01
The method one step linear reconstruction method for continuous wave diffuse optical tomography is proposed and demonstrated for polyvinyl chloride based material and breast phantom. Approximation which used in this method is selecting regulation coefficient and evaluating the difference between two states that corresponding to the data acquired without and with a change in optical properties. This method is used to recovery of optical parameters from measured boundary data of light propagation in the object. The research is demonstrated by simulation and experimental data. Numerical object is used to produce simulation data. Chloride based material and breast phantom sample is used to produce experimental data. Comparisons of results between experiment and simulation data are conducted to validate the proposed method. The results of the reconstruction image which is produced by the one step linear reconstruction method show that the image reconstruction almost same as the original object. This approach provides a means of imaging that is sensitive to changes in optical properties, which may be particularly useful for functional imaging used continuous wave diffuse optical tomography of early diagnosis of breast cancer.
Thermal Diffusivity of Sweet Potato Flour Measured Using Dickerson Method
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I.K. Tastra
2006-08-01
Full Text Available Sweet potato (Ipmoea batatas I. is one the carbohydrate sources in indonesia that can be used both for food and industry purposes. To support the utilization of sweet potato as flour, it is imperative to develop a drying system that can improve its quality. A preliminary study using an improved variety, namely Sari, was conducted to determine its floure thermal diffusivity ( , an imprortant parameter in developing drying process. The experiment was run according to Dickerson method using sweet potato flour at different levels of moisture content (5.05-5.97% wet basis and temperatures (23.7 -40.9 oC this method used an apparatus based on transient heat transfer condition requiring only a time- temperature data. At the levels of moisture and temperature studied, the thermal diffusivity of sweet potato flour could be expressed using a linear regression model, = 10-9 M.T + 9X 10-9( R2=0.9779. the average value of the thermal diffusivity sweet potato flour was 1.72 x 10-7 m2/s at a moisture level of 5.51 % wet basis and temperature of 29.58 oC. Similar studies are needed for different varieties or cultivars of sweet potato as well at a wide range of moisture content and temperature content and temperature levels.
Proposal for a Five-Step Method to Elicit Expert Judgment
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Duco Veen
2017-12-01
Full Text Available Elicitation is a commonly used tool to extract viable information from experts. The information that is held by the expert is extracted and a probabilistic representation of this knowledge is constructed. A promising avenue in psychological research is to incorporated experts’ prior knowledge in the statistical analysis. Systematic reviews on elicitation literature however suggest that it might be inappropriate to directly obtain distributional representations from experts. The literature qualifies experts’ performance on estimating elements of a distribution as unsatisfactory, thus reliably specifying the essential elements of the parameters of interest in one elicitation step seems implausible. Providing feedback within the elicitation process can enhance the quality of the elicitation and interactive software can be used to facilitate the feedback. Therefore, we propose to decompose the elicitation procedure into smaller steps with adjustable outcomes. We represent the tacit knowledge of experts as a location parameter and their uncertainty concerning this knowledge by a scale and shape parameter. Using a feedback procedure, experts can accept the representation of their beliefs or adjust their input. We propose a Five-Step Method which consists of (1 Eliciting the location parameter using the trial roulette method. (2 Provide feedback on the location parameter and ask for confirmation or adjustment. (3 Elicit the scale and shape parameter. (4 Provide feedback on the scale and shape parameter and ask for confirmation or adjustment. (5 Use the elicited and calibrated probability distribution in a statistical analysis and update it with data or to compute a prior-data conflict within a Bayesian framework. User feasibility and internal validity for the Five-Step Method are investigated using three elicitation studies.
Imaginary Time Step Method to Solve the Dirac Equation with Nonlocal Potential
International Nuclear Information System (INIS)
Zhang Ying; Liang Haozhao; Meng Jie
2009-01-01
The imaginary time step (ITS) method is applied to solve the Dirac equation with nonlocal potentials in coordinate space. Taking the nucleus 12 C as an example, even with nonlocal potentials, the direct ITS evolution for the Dirac equation still meets the disaster of the Dirac sea. However, following the recipe in our former investigation, the disaster can be avoided by the ITS evolution for the corresponding Schroedinger-like equation without localization, which gives the convergent results exactly the same with those obtained iteratively by the shooting method with localized effective potentials.
Solving the dirac equation with nonlocal potential by imaginary time step method
International Nuclear Information System (INIS)
Zhang Ying; Liang Haozhao; Meng Jie
2009-01-01
The imaginary time step (ITS) method is applied to solve the Dirac equation with the nonlocal potential in coordinate space by the ITS evolution for the corresponding Schroedinger-like equation for the upper component. It is demonstrated that the ITS evolution can be equivalently performed for the Schroedinger-like equation with or without localization. The latter algorithm is recommended in the application for the reason of simplicity and efficiency. The feasibility and reliability of this algorithm are also illustrated by taking the nucleus 16 O as an example, where the same results as the shooting method for the Dirac equation with localized effective potentials are obtained. (authors)
Susyanto, N.; Veldhuis, Raymond N.J.; Spreeuwers, Lieuwe Jan; Klaassen, C.A.J.
2016-01-01
We propose a new method for combining multi-algorithm score-based face recognition systems, which we call the two-step calibration method. Typically, algorithms for face recognition systems produce dependent scores. The two-step method is based on parametric copulas to handle this dependence. Its
Thermal-hydraulic stability tests for newly designed BWR rod bundle (step-III fuel type B)
International Nuclear Information System (INIS)
Ito, Y.; Itami, A.; Tsuda, K.; Nakamura, K.; Ishikawa, M.; Toba, A.; Omoto, A.
2004-01-01
The Step-III Fuel Type B is a new fuel design for high burn-up operation in BWRs in Japan. The fuel design uses a 9x9 - 9 rod bundle to accommodate the high fuel duty of high burn-up operation and a square water-channel to provide enhanced neutron moderation. The objective of this study is to confirm the thermal-hydraulic stability performance of the new fuel design by tests which simulate the parallel channel configuration of the BWR core. The stability testing was performed at the NFI test loop. The test bundle geometry used for the stability test is a 3x3 heater rod bundle which has about 1/8 of the cross section area of the full size 9x9 - 9 rod bundle. Full size heater rods were used to simulate the fuel rods. For parallel channel simulation, a bypass channel with a 6x6 - 8 heater rod bundle was connected in parallel with the 3x3 rod bundle test channel. The stability test results showed typical flow oscillation features which have been described as density wave oscillations. The stationary limit cycle oscillation extended flow amplitudes to several tens of a percent of the nominal value, during which periodic dry-out and re-wetting were observed. The test results were used for verification of a stability analysis code, which demonstrated that the stability performance of the new fuel design has been conservatively predicted. (author)
A two-step computer-assisted method for deriving steady-state rate equations.
Fromm, S J; Fromm, H J
1999-11-19
A number of computer-assisted methods have been described for the derivation of enzyme-catalyzed steady-state rate equations [K. R. Runyan and R. B. Gunn (1989) Methods Enzymol. 171, 164-190; R. Varon, F. Garcia-Seville, M. Garvia-Moreno, F. Garcia-Canovas, R. Peyro, and R. G. Duggleby (1997) Comput. Appl. Biosci. 13, 159-167]; however, the required programs are either not readily available or require special software. We present here a two-step computer-assisted procedure for deriving steady-state rate equations using the widely available program Mathematica. In the first step, the differential equations for a particular kinetic mechanism that describe changes in enzyme concentration as a function of time are set equal to zero and entered into Mathematica in matrix form. In the second step, a single command allows for the computation of the distribution equations for the free enzyme and each enzyme-ligand complex. Copyright 1999 Academic Press.
Analytical methods for toxic gases from thermal degradation of polymers
Hsu, M.-T. S.
1977-01-01
Toxic gases evolved from the thermal oxidative degradation of synthetic or natural polymers in small laboratory chambers or in large scale fire tests are measured by several different analytical methods. Gas detector tubes are used for fast on-site detection of suspect toxic gases. The infrared spectroscopic method is an excellent qualitative and quantitative analysis for some toxic gases. Permanent gases such as carbon monoxide, carbon dioxide, methane and ethylene, can be quantitatively determined by gas chromatography. Highly toxic and corrosive gases such as nitrogen oxides, hydrogen cyanide, hydrogen fluoride, hydrogen chloride and sulfur dioxide should be passed into a scrubbing solution for subsequent analysis by either specific ion electrodes or spectrophotometric methods. Low-concentration toxic organic vapors can be concentrated in a cold trap and then analyzed by gas chromatography and mass spectrometry. The limitations of different methods are discussed.
The Step Method - Battling Identity Theft Using E-Retailers' Websites
Schulze, Marion; Shah, Mahmood H.
Identity theft is the fastest growing crime in the 21st century. This paper investigates firstly what well-known e-commerce organizations are communicating on their websites to address this issue. For this purpose we analyze secondary data (literature and websites of ten organizations). Secondly we investigate the good practice in this area and recommend practical steps. The key findings are that some organizations only publish minimum security information to comply with legal requirements. Others inform consumers on how they actively try to prevent identity theft, how consumers can protect themselves, and about supporting actions when identity theft related fraud actually happens. From these findings we developed the Support - Trust - Empowerment -Prevention (STEP) method. It is aimed at helping to prevent identity theft and dealing with consequences when it occurs. It can help organizations on gaining and keeping consumers’ trust which is so essential for e-retailers in a climate of rising fraud.
Cao, X M; Tian, Y; Wang, Z Y; Liu, Y W; Wang, C X
2016-07-03
Thermal denaturation of lysozymes was studied as a function of protein concentration, phosphate buffer concentration, and scan rate using differential scanning calorimetry (DSC), which was then analyzed by the isoconversional method. The results showed that lysozyme thermal denaturation was only slightly affected by the protein concentration and scan rate. When the protein concentration and scan rate increased, the denaturation temperature (Tm) also increased accordingly. On the contrary, the Tm decreased with the increase of phosphate buffer concentration. The denaturation process of lysozymes was accelatated and the thermal stability was reduced with the increase of phosphate concentration. One part of degeneration process was not reversible where the aggregation occurred. The other part was reversible. The apparent activation energy (Ea) was computed by the isoconversional method. It decreased with the increase of the conversion ratio (α). The observed denaturation process could not be described by a simple reaction mechanism. It was not a process involving 2 standard reversible states, but a multi-step process. The new opportunities for investigating the kinetics process of protein denaturation can be supplied by this novel isoconversional method.
Avoid the tsunami of the Dirac sea in the imaginary time step method
International Nuclear Information System (INIS)
Zhang, Ying; Liang, Haozhao; Meng, Jie
2010-01-01
The discrete single-particle spectra in both the Fermi and Dirac sea have been calculated by the imaginary time step (ITS) method for the Schroedinger-like equation after avoiding the "tsunami" of the Dirac sea, i.e. the diving behavior of the single-particle level into the Dirac sea in the direct application of the ITS method for the Dirac equation. It is found that by the transform from the Dirac equation to the Schroedinger-like equation, the single-particle spectra, which extend from the positive to the negative infinity, can be separately obtained by the ITS evolution in either the Fermi sea or the Dirac sea. Identical results with those in the conventional shooting method have been obtained via the ITS evolution for the equivalent Schroedinger-like equation, which demonstrates the feasibility, practicality and reliability of the present algorithm and dispels the doubts on the ITS method in the relativistic system. (author)
An Online Non-Invasive Condition Monitoring Method for Stepping Motor CRDM in HTGR
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S. Bakhri
2016-12-01
Full Text Available Control Rod Drive Mechanism (CRDM based on stepping motor is one of the components applied in High Temperature Gas Coold Reactor (HTGR to control the reactivity as well as to maintain the safety of reactor. The stepping motor requires a unique condition monitoring to avoid any failures especially due to the specific environments of CRDM in HTGR such as the allowable of high temperature, high radiation and the location of stepper motor inside a pressure shell. This research aims to demonstrate an online non-invasive condition monitoring method without direct access to the CRDM of HTGR based on voltage and stator current measurements. A simple stepping motor CRDM simulator is employed. The online condition monitoring is carried out by direct pattern matching of the output signals of logic generator block and the output signals of motor driver. The online method utilizes signature patterns of voltage and stator current signals of the healthy motor as a baseline for healthy motor. In addition, the method is applied to detect high-resistance problem on the connector between the motor driver block and the stepper motor to show the effectiveness and the applicability of this method. The online condition monitoring system demonstrates a capability to identify a minimum detectable simulated high-resistance for about 2.9% which decreases the measured stator current and motor’s torque for around 5.1% and 3.3%, respectively. The paper also points out signatures of healthy motor, including mutual inductions of the motor’s winding in voltage and current measurement which can be used as the fault symptom indicators for online monitoring purposes.
Influence of application methods of one-step self-etching adhesives on microtensile bond strength
Directory of Open Access Journals (Sweden)
Chul-Kyu Choi,
2011-05-01
Full Text Available Objectives The purpose of this study was to evaluate the effect of various application methods of one-step self-etch adhesives to microtensile resin-dentin bond strength. Materials and Methods Thirty-six extracted human molars were used. The teeth were assigned randomly to twelve groups (n = 15, according to the three different adhesive systems (Clearfil Tri-S Bond, Adper Prompt L-Pop, G-Bond and application methods. The adhesive systems were applied on the dentin as follows: 1 The single coating, 2 The double coating, 3 Manual agitation, 4 Ultrasonic agitation. Following the adhesive application, light-cure composite resin was constructed. The restored teeth were stored in distilled water at room temperature for 24 hours, and prepared 15 specimens per groups. Then microtensile bond strength was measured and the failure mode was examined. Results Manual agitation and ultrasonic agitation of adhesive significantly increased the microtensile bond strength than single coating and double coating did. Double coating of adhesive significantly increased the microtensile bond strength than single coating did and there was no significant difference between the manual agitation and ultrasonic agitation group. There was significant difference in microtensile bonding strength among all adhesives and Clearfil Tri-S Bond showed the highest bond strength. Conclusions In one-step self-etching adhesives, there was significant difference according to application methods and type of adhesives. No matter of the material, the manual or ultrasonic agitation of the adhesive showed significantly higher microtensile bond strength.
de Koning, S.; Kaal, E.; Janssen, H.-G.; van Platerink, C.; Brinkman, U.A.Th.
2008-01-01
The feasibility of a versatile system for multi-step direct thermal desorption (DTD) coupled to comprehensive gas chromatography (GC × GC) with time-of-flight mass spectrometric (TOF-MS) detection is studied. As an application the system is used for the characterization of fresh versus aged olive
Liu, Dong; Wu, Lili; Li, Chunxiu; Ren, Shengqiang; Zhang, Jingquan; Li, Wei; Feng, Lianghuan
2015-08-05
The methylammonium lead halide perovskite solar cells have become very attractive because they can be prepared with low-cost solution-processable technology and their power conversion efficiency have been increasing from 3.9% to 20% in recent years. However, the high performance of perovskite photovoltaic devices are dependent on the complicated process to prepare compact perovskite films with large grain size. Herein, a new method is developed to achieve excellent CH3NH3PbI3-xClx film with fine morphology and crystallization based on one step deposition and two-step annealing process. This method include the spin coating deposition of the perovskite films with the precursor solution of PbI2, PbCl2, and CH3NH3I at the molar ratio 1:1:4 in dimethylformamide (DMF) and the post two-step annealing (TSA). The first annealing is achieved by solvent-induced process in DMF to promote migration and interdiffusion of the solvent-assisted precursor ions and molecules and realize large size grain growth. The second annealing is conducted by thermal-induced process to further improve morphology and crystallization of films. The compact perovskite films are successfully prepared with grain size up to 1.1 μm according to SEM observation. The PL decay lifetime, and the optic energy gap for the film with two-step annealing are 460 ns and 1.575 eV, respectively, while they are 307 and 327 ns and 1.577 and 1.582 eV for the films annealed in one-step thermal and one-step solvent process. On the basis of the TSA process, the photovoltaic devices exhibit the best efficiency of 14% under AM 1.5G irradiation (100 mW·cm(-2)).
Diaby, Vakaramoko; Goeree, Ron
2014-02-01
In recent years, the quest for more comprehensiveness, structure and transparency in reimbursement decision-making in healthcare has prompted the research into alternative decision-making frameworks. In this environment, multi-criteria decision analysis (MCDA) is arising as a valuable tool to support healthcare decision-making. In this paper, we present the main MCDA decision support methods (elementary methods, value-based measurement models, goal programming models and outranking models) using a case study approach. For each family of methods, an example of how an MCDA model would operate in a real decision-making context is presented from a critical perspective, highlighting the parameters setting, the selection of the appropriate evaluation model as well as the role of sensitivity and robustness analyses. This study aims to provide a step-by-step guide on how to use MCDA methods for reimbursement decision-making in healthcare.
Nonequilibrium Green's function method for quantum thermal transport
Wang, Jian-Sheng; Agarwalla, Bijay Kumar; Li, Huanan; Thingna, Juzar
2014-12-01
This review deals with the nonequilibrium Green's function (NEGF) method applied to the problems of energy transport due to atomic vibrations (phonons), primarily for small junction systems. We present a pedagogical introduction to the subject, deriving some of the well-known results such as the Laudauer-like formula for heat current in ballistic systems. The main aim of the review is to build the machinery of the method so that it can be applied to other situations, which are not directly treated here. In addition to the above, we consider a number of applications of NEGF, not in routine model system calculations, but in a few new aspects showing the power and usefulness of the formalism. In particular, we discuss the problems of multiple leads, coupled left-right-lead system, and system without a center. We also apply the method to the problem of full counting statistics. In the case of nonlinear systems, we make general comments on the thermal expansion effect, phonon relaxation time, and a certain class of mean-field approximations. Lastly, we examine the relationship between NEGF, reduced density matrix, and master equation approaches to thermal transport.
DEVELOPMENT OF AN ITERATIVE METHOD TO SOLVE THE DIFFUSION PROBLEM IN THE PREDESIGN STEP
Abouali Sanchez, Said
2014-01-01
One of the most important and difficult steps in the design process is the predesign. In this step, the main goal is to obtain the geometry characteristics and some other features to solve the problem we want to solve. Thus, reducing the duration of this phase is one of the challenging objectives in the actual engineering design process. As regards our study, following the energy deposition calculations with the means of the FLUKA code, a heat diffusion code is usually needed to calculate the evolution in time of the temperature distributions as well the associated stresses on the object under study. As a preliminary optimization step in the object design process, in this project we are proposing thedevelopment of a new method implemented in a code which allows us to obtain the solution for this equation in a complex geometry by using the information given by the FLUKA code for a simple geometry. By this way, we will be able to reduce the predesign phase duration.
Parallelization methods study of thermal-hydraulics codes
International Nuclear Information System (INIS)
Gaudart, Catherine
2000-01-01
The variety of parallelization methods and machines leads to a wide selection for programmers. In this study we suggest, in an industrial context, some solutions from the experience acquired through different parallelization methods. The study is about several scientific codes which simulate a large variety of thermal-hydraulics phenomena. A bibliography on parallelization methods and a first analysis of the codes showed the difficulty of our process on the whole applications to study. Therefore, it would be necessary to identify and extract a representative part of these applications and parallelization methods. The linear solver part of the codes forced itself. On this particular part several parallelization methods had been used. From these developments one could estimate the necessary work for a non initiate programmer to parallelize his application, and the impact of the development constraints. The different methods of parallelization tested are the numerical library PETSc, the parallelizer PAF, the language HPF, the formalism PEI and the communications library MPI and PYM. In order to test several methods on different applications and to follow the constraint of minimization of the modifications in codes, a tool called SPS (Server of Parallel Solvers) had be developed. We propose to describe the different constraints about the optimization of codes in an industrial context, to present the solutions given by the tool SPS, to show the development of the linear solver part with the tested parallelization methods and lastly to compare the results against the imposed criteria. (author) [fr
Gao, Peifeng; Zhao, Xinying; He, Muyi; Liu, Qingsheng; Qu, Feng
2013-06-01
One-step and two-step capillary isoelectric focusing (clEF) methods were employed the separation and pI determination of proteins and polypeptides. The parameters affecting the analysis efficiency, such as the sample solution, injection volume, focusing voltage, focusing time and driving conditions were optimized. The comparison of the two methods for separation of cytochrome C, hemoglobin, myoglobin, transferrin, bovine serum albumin and six polypeptides showed that the one-step cIEF was simple and fast, which could determine the pI of single component as well as it was rapid for protein and polypeptide separation, but it could not get good resolution or accurate pI of each component in a mixed sample. The two-step cIEF was more complex and needed longer time, however, which could separate and exactly determine the pI of each component in the mixture, and the pI value of each component determined was consistent with that determined using a single sample. The two methods are complementary, and can be widely used in rapid and accurate determination of the pI of amphiphilic biological particles.
On analysis-based two-step interpolation methods for randomly sampled seismic data
Yang, Pengliang; Gao, Jinghuai; Chen, Wenchao
2013-02-01
Interpolating the missing traces of regularly or irregularly sampled seismic record is an exceedingly important issue in the geophysical community. Many modern acquisition and reconstruction methods are designed to exploit the transform domain sparsity of the few randomly recorded but informative seismic data using thresholding techniques. In this paper, to regularize randomly sampled seismic data, we introduce two accelerated, analysis-based two-step interpolation algorithms, the analysis-based FISTA (fast iterative shrinkage-thresholding algorithm) and the FPOCS (fast projection onto convex sets) algorithm from the IST (iterative shrinkage-thresholding) algorithm and the POCS (projection onto convex sets) algorithm. A MATLAB package is developed for the implementation of these thresholding-related interpolation methods. Based on this package, we compare the reconstruction performance of these algorithms, using synthetic and real seismic data. Combined with several thresholding strategies, the accelerated convergence of the proposed methods is also highlighted.
Development of a three dimensional circulation model based on fractional step method
Directory of Open Access Journals (Sweden)
Mazen Abualtayef
2010-03-01
Full Text Available A numerical model was developed for simulating a three-dimensional multilayer hydrodynamic and thermodynamic model in domains with irregular bottom topography. The model was designed for examining the interactions between flow and topography. The model was based on the three-dimensional Navier-Stokes equations and was solved using the fractional step method, which combines the finite difference method in the horizontal plane and the finite element method in the vertical plane. The numerical techniques were described and the model test and application were presented. For the model application to the northern part of Ariake Sea, the hydrodynamic and thermodynamic results were predicted. The numerically predicted amplitudes and phase angles were well consistent with the field observations.
Directory of Open Access Journals (Sweden)
George OGUNTALA
2017-08-01
Full Text Available In this study, the thermal performance analysis of porous fin with temperature-dependent thermal conductivity and internal heat generation is carried out using Haar wavelet collocation method. The effects of various parameters on the thermal characteristics of the porous fin are investigated. It is found that as the porosity increases, the rate of heat transfer from the fin increases and the thermal performance of the porous fin increases. The numerical solutions by the Haar wavelet collocation method are in good agreement with the standard numerical solutions.
Rapid expansion method (REM) for time‐stepping in reverse time migration (RTM)
Pestana, Reynam C.
2009-01-01
We show that the wave equation solution using a conventional finite‐difference scheme, derived commonly by the Taylor series approach, can be derived directly from the rapid expansion method (REM). After some mathematical manipulation we consider an analytical approximation for the Bessel function where we assume that the time step is sufficiently small. From this derivation we find that if we consider only the first two Chebyshev polynomials terms in the rapid expansion method we can obtain the second order time finite‐difference scheme that is frequently used in more conventional finite‐difference implementations. We then show that if we use more terms from the REM we can obtain a more accurate time integration of the wave field. Consequently, we have demonstrated that the REM is more accurate than the usual finite‐difference schemes and it provides a wave equation solution which allows us to march in large time steps without numerical dispersion and is numerically stable. We illustrate the method with post and pre stack migration results.
A three-step method of self-reflection using reflective journal writing.
Riley-Doucet, C; Wilson, S
1997-05-01
Fiscal and financial constraints present a challenge for nurse educators to broaden the diversity and scope of teaching/learning methodologies. One method designed to promote autonomy and self-direction of nursing students is self-reflection combined with reflective journal writing. This paper describes a three-step process of self-reflection encompassing critical appraisal, peer group discussion and self-awareness. This process of self-reflection was initiated with one group of clinical nursing students. Using student and teacher feedback, implications for employing this teaching/learning strategy in clinical practice are suggested.
Directory of Open Access Journals (Sweden)
Jixin Wang
2014-06-01
Full Text Available This paper presents a rational prediction of temperature field on the differential hybrid system (DHS based on the thermal network method (TNM. The whole thermal network model is built by considering both the contact thermal resistance between gasket and planet gear and the temperature effect on the physical property parameters of lubricant. The contact thermal resistance is obtained by using the concept of contact branch thermal resistance and G-W elastic model. By building an elaborate thermal network model and computing models for power losses and thermal resistances between components, the whole temperature field of DHS under typical operating condition is predicted. Results show that thermal network method can be effectively used to predict the temperature distribution and the rule of temperature variation, the surface roughness significantly affects contact thermal conduction, and the decrease in the thermal resistance of the natural convection between air and DHS housing can effectively improve the thermal environment of DHS.
Jagtap, Pratik; Goslinga, Jill; Kooren, Joel A; McGowan, Thomas; Wroblewski, Matthew S; Seymour, Sean L; Griffin, Timothy J
2013-04-01
Large databases (>10(6) sequences) used in metaproteomic and proteogenomic studies present challenges in matching peptide sequences to MS/MS data using database-search programs. Most notably, strict filtering to avoid false-positive matches leads to more false negatives, thus constraining the number of peptide matches. To address this challenge, we developed a two-step method wherein matches derived from a primary search against a large database were used to create a smaller subset database. The second search was performed against a target-decoy version of this subset database merged with a host database. High confidence peptide sequence matches were then used to infer protein identities. Applying our two-step method for both metaproteomic and proteogenomic analysis resulted in twice the number of high confidence peptide sequence matches in each case, as compared to the conventional one-step method. The two-step method captured almost all of the same peptides matched by the one-step method, with a majority of the additional matches being false negatives from the one-step method. Furthermore, the two-step method improved results regardless of the database search program used. Our results show that our two-step method maximizes the peptide matching sensitivity for applications requiring large databases, especially valuable for proteogenomics and metaproteomics studies. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Yeral, M Ilkin; Ozgu-Erdinc, A Seval; Uygur, Dilek; Seckin, K Doga; Karsli, M Fatih; Danisman, A Nuri
2014-08-01
Our aim was to evaluate and compare the diagnostic performance of three methods commonly used for GDM screening: fasting plasma glucose (FPG), two-step 50 g glucose challenge test (GCT), and 75 g glucose tolerance test (GTT) in a randomized study design to predict GDM in the first trimester and determine the best approach in predicting GDM. In a non-blind, parallel-group prospective randomized controlled study; 736 singleton pregnant women underwent FPG testing in the first trimester and randomly assigned to two groups; two-step 50 g GCT and 75 g GTT. GDM diagnosis was made according to Carpenter-Coustan or ADA (American Diabetes Association) criteria in two-step 50 g GCT and 75 g GTT groups, respectively. Subsequent testing was performed by two-step 50 g GCT at 24-28 weeks for screen negatives. After excluding the women who were lost to follow-up or withdrawn as a result of pregnancy loss, 486 pregnant women were recruited in the study. The FPG, two-step GCT, and one-step GTT methods identified GDM in 25/486 (5.1 %), 15/248 (6.0 %), and 27/238 (11.3 %) women, respectively. Area under ROC curves were 0.623, 0.708, and 0.792, respectively. Sensitivities were 47.17, 68.18, and 87.1 %, respectively. Specificities were 77.37, 100, and 100 %, respectively. Positive predictive values were 20.33, 100, and 100 %, respectively. Negative predictive values were 92.29, 97, and 98.1 %, respectively. Until superior screening alternatives become available, the 75 g GTT may be preferred for GDM screening in the first trimester.
Design of materials with extreme thermal expansion using a three-phase topology optimization method
DEFF Research Database (Denmark)
Sigmund, Ole; Torquato, S.
1997-01-01
expansion, zero thermal expansion, and negative thermal expansion. Assuming linear elasticity, it is shown that materials with effective negative thermal expansion coefficients can be obtained by mixing two phases with positive thermal expansion coefficients and void. We also show......We show how composites with extremal or unusual thermal expansion coefficients can be designed using a numerical topology optimization method. The composites are composed of two different material phases and void. The optimization method is illustrated by designing materials having maximum thermal...... that there is no mechanistic relationship between negative thermal expansion and negative Poisson's ratio....
Methods and tools to detect thermal noise in fast reactors
International Nuclear Information System (INIS)
Motta, M.; Giovannini, R.
1985-07-01
The Specialists' Meeting on ''Methods and Tools to Detect Thermal Noise in Fast Reactors'' was held in Bologna on 8-10 October 1984. The meeting was hosted by the ENEA and was sponsored by the IAEA on the recommendation of the International Working Group on Fast Reactors. 17 participants attended the meeting from France, the Federal Republic of Germany, Italy, Japan, the United Kingdom, Joint Research Centre of CEC and from IAEA. The meeting was presided over by Prof. Mario Motta of Italy. The purpose of the meeting was to review and discuss methods and tools for temperature noise detection and related analysis as a potential means for detecting local blockages in fuel and blanket subassemblies and other faults in LMFBR. The meeting was divided into four technical sessions as follows: 1. National review presentations on application purposes and research activities for thermal noise detection. (5 papers); 2. Detection instruments and electronic equipment for temperature measurements in fast reactors. (5 papers); 3. Physical models. (2 papers); 4. Signal processing techniques. (3 papers). A separate abstract was prepared for each of these papers
Teaching Thermal Hydraulics & Numerical Methods: An Introductory Control Volume Primer
Energy Technology Data Exchange (ETDEWEB)
D. S. Lucas
2004-10-01
A graduate level course for Thermal Hydraulics (T/H) was taught through Idaho State University in the spring of 2004. A numerical approach was taken for the content of this course since the students were employed at the Idaho National Laboratory and had been users of T/H codes. The majority of the students had expressed an interest in learning about the Courant Limit, mass error, semi-implicit and implicit numerical integration schemes in the context of a computer code. Since no introductory text was found the author developed notes taught from his own research and courses taught for Westinghouse on the subject. The course started with a primer on control volume methods and the construction of a Homogeneous Equilibrium Model (HEM) (T/H) code. The primer was valuable for giving the students the basics behind such codes and their evolution to more complex codes for Thermal Hydraulics and Computational Fluid Dynamics (CFD). The course covered additional material including the Finite Element Method and non-equilibrium (T/H). The control volume primer and the construction of a three-equation (mass, momentum and energy) HEM code are the subject of this paper . The Fortran version of the code covered in this paper is elementary compared to its descendants. The steam tables used are less accurate than the available commercial version written in C Coupled to a Graphical User Interface (GUI). The Fortran version and input files can be downloaded at www.microfusionlab.com.
Validation of a One-Step Method for Extracting Fatty Acids from Salmon, Chicken and Beef Samples.
Zhang, Zhichao; Richardson, Christine E; Hennebelle, Marie; Taha, Ameer Y
2017-10-01
Fatty acid extraction methods are time-consuming and expensive because they involve multiple steps and copious amounts of extraction solvents. In an effort to streamline the fatty acid extraction process, this study compared the standard Folch lipid extraction method to a one-step method involving a column that selectively elutes the lipid phase. The methods were tested on raw beef, salmon, and chicken. Compared to the standard Folch method, the one-step extraction process generally yielded statistically insignificant differences in chicken and salmon fatty acid concentrations, percent composition and weight percent. Initial testing showed that beef stearic, oleic and total fatty acid concentrations were significantly lower by 9-11% with the one-step method as compared to the Folch method, but retesting on a different batch of samples showed a significant 4-8% increase in several omega-3 and omega-6 fatty acid concentrations with the one-step method relative to the Folch. Overall, the findings reflect the utility of a one-step extraction method for routine and rapid monitoring of fatty acids in chicken and salmon. Inconsistencies in beef concentrations, although minor (within 11%), may be due to matrix effects. A one-step fatty acid extraction method has broad applications for rapidly and routinely monitoring fatty acids in the food supply and formulating controlled dietary interventions. © 2017 Institute of Food Technologists®.
s-Step Krylov Subspace Methods as Bottom Solvers for Geometric Multigrid
Energy Technology Data Exchange (ETDEWEB)
Williams, Samuel [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Lijewski, Mike [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Almgren, Ann [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Straalen, Brian Van [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Carson, Erin [Univ. of California, Berkeley, CA (United States); Knight, Nicholas [Univ. of California, Berkeley, CA (United States); Demmel, James [Univ. of California, Berkeley, CA (United States)
2014-08-14
Geometric multigrid solvers within adaptive mesh refinement (AMR) applications often reach a point where further coarsening of the grid becomes impractical as individual sub domain sizes approach unity. At this point the most common solution is to use a bottom solver, such as BiCGStab, to reduce the residual by a fixed factor at the coarsest level. Each iteration of BiCGStab requires multiple global reductions (MPI collectives). As the number of BiCGStab iterations required for convergence grows with problem size, and the time for each collective operation increases with machine scale, bottom solves in large-scale applications can constitute a significant fraction of the overall multigrid solve time. In this paper, we implement, evaluate, and optimize a communication-avoiding s-step formulation of BiCGStab (CABiCGStab for short) as a high-performance, distributed-memory bottom solver for geometric multigrid solvers. This is the first time s-step Krylov subspace methods have been leveraged to improve multigrid bottom solver performance. We use a synthetic benchmark for detailed analysis and integrate the best implementation into BoxLib in order to evaluate the benefit of a s-step Krylov subspace method on the multigrid solves found in the applications LMC and Nyx on up to 32,768 cores on the Cray XE6 at NERSC. Overall, we see bottom solver improvements of up to 4.2x on synthetic problems and up to 2.7x in real applications. This results in as much as a 1.5x improvement in solver performance in real applications.
Deposit and scale prevention methods in thermal sea water desalination
International Nuclear Information System (INIS)
Froehner, K.R.
1977-01-01
Introductory remarks deal with the 'fouling factor' and its influence on the overall heat transfer coefficient of msf evaporators. The composition of the matter dissolved in sea water and the thermal and chemical properties lead to formation of alkaline scale or even hard, sulphate scale on the heat exchanger tube walls and can hamper plant operation and economics seriously. Among the scale prevention methods are 1) pH control by acid dosing (decarbonation), 2) 'threshold treatment' by dosing of inhibitors of different kind, 3) mechanical cleaning by sponge rubber balls guided through the heat exchanger tubes, in general combined with methods no. 1 or 2, and 4) application of a scale crystals germ slurry (seeding). Mention is made of several other scale prevention proposals. The problems encountered with marine life (suspension, deposit, growth) in desalination plants are touched. (orig.) [de
Thermal Efficiency Degradation Diagnosis Method Using Regression Model
International Nuclear Information System (INIS)
Jee, Chang Hyun; Heo, Gyun Young; Jang, Seok Won; Lee, In Cheol
2011-01-01
This paper proposes an idea for thermal efficiency degradation diagnosis in turbine cycles, which is based on turbine cycle simulation under abnormal conditions and a linear regression model. The correlation between the inputs for representing degradation conditions (normally unmeasured but intrinsic states) and the simulation outputs (normally measured but superficial states) was analyzed with the linear regression model. The regression models can inversely response an associated intrinsic state for a superficial state observed from a power plant. The diagnosis method proposed herein is classified into three processes, 1) simulations for degradation conditions to get measured states (referred as what-if method), 2) development of the linear model correlating intrinsic and superficial states, and 3) determination of an intrinsic state using the superficial states of current plant and the linear regression model (referred as inverse what-if method). The what-if method is to generate the outputs for the inputs including various root causes and/or boundary conditions whereas the inverse what-if method is the process of calculating the inverse matrix with the given superficial states, that is, component degradation modes. The method suggested in this paper was validated using the turbine cycle model for an operating power plant
Solving delay differential equations in S-ADAPT by method of steps.
Bauer, Robert J; Mo, Gary; Krzyzanski, Wojciech
2013-09-01
S-ADAPT is a version of the ADAPT program that contains additional simulation and optimization abilities such as parametric population analysis. S-ADAPT utilizes LSODA to solve ordinary differential equations (ODEs), an algorithm designed for large dimension non-stiff and stiff problems. However, S-ADAPT does not have a solver for delay differential equations (DDEs). Our objective was to implement in S-ADAPT a DDE solver using the methods of steps. The method of steps allows one to solve virtually any DDE system by transforming it to an ODE system. The solver was validated for scalar linear DDEs with one delay and bolus and infusion inputs for which explicit analytic solutions were derived. Solutions of nonlinear DDE problems coded in S-ADAPT were validated by comparing them with ones obtained by the MATLAB DDE solver dde23. The estimation of parameters was tested on the MATLB simulated population pharmacodynamics data. The comparison of S-ADAPT generated solutions for DDE problems with the explicit solutions as well as MATLAB produced solutions which agreed to at least 7 significant digits. The population parameter estimates from using importance sampling expectation-maximization in S-ADAPT agreed with ones used to generate the data. Published by Elsevier Ireland Ltd.
Novel two-step method to form silk fibroin fibrous hydrogel
International Nuclear Information System (INIS)
Ming, Jinfa; Li, Mengmeng; Han, Yuhui; Chen, Ying; Li, Han; Zuo, Baoqi; Pan, Fukui
2016-01-01
Hydrogels prepared by silk fibroin solution have been studied. However, mimicking the nanofibrous structures of extracellular matrix for fabricating biomaterials remains a challenge. Here, a novel two-step method was applied to prepare fibrous hydrogels using regenerated silk fibroin solution containing nanofibrils in a range of tens to hundreds of nanometers. When the gelation process of silk solution occurred, it showed a top-down type gel within 30 min. After gelation, silk fibroin fibrous hydrogels exhibited nanofiber network morphology with β-sheet structure. Moreover, the compressive stress and modulus of fibrous hydrogels were 31.9 ± 2.6 and 2.8 ± 0.8 kPa, respectively, which was formed using 2.0 wt.% concentration solutions. In addition, fibrous hydrogels supported BMSCs attachment and proliferation over 12 days. This study provides important insight in the in vitro processing of silk fibroin into useful new materials. - Highlights: • SF fibrous hydrogel was prepared by a novel two-step method. • SF solution containing nanofibrils in a range of tens to hundreds of nanometers was prepared. • Gelation process was top-down type gel with several minutes. • SF fibrous hydrogels exhibited nanofiber network morphology with β-sheet structure. • Fibrous hydrogels had higher compressive stresses superior to porous hydrogels.
Thermal Modeling Method Improvements for SAGE III on ISS
Liles, Kaitlin; Amundsen, Ruth; Davis, Warren; McLeod, Shawn
2015-01-01
The Stratospheric Aerosol and Gas Experiment III (SAGE III) instrument is the fifth in a series of instruments developed for monitoring aerosols and gaseous constituents in the stratosphere and troposphere. SAGE III will be delivered to the International Space Station (ISS) via the SpaceX Dragon vehicle. A detailed thermal model of the SAGE III payload, which consists of multiple subsystems, has been developed in Thermal Desktop (TD). Many innovative analysis methods have been used in developing this model; these will be described in the paper. This paper builds on a paper presented at TFAWS 2013, which described some of the initial developments of efficient methods for SAGE III. The current paper describes additional improvements that have been made since that time. To expedite the correlation of the model to thermal vacuum (TVAC) testing, the chambers and GSE for both TVAC chambers at Langley used to test the payload were incorporated within the thermal model. This allowed the runs of TVAC predictions and correlations to be run within the flight model, thus eliminating the need for separate models for TVAC. In one TVAC test, radiant lamps were used which necessitated shooting rays from the lamps, and running in both solar and IR wavebands. A new Dragon model was incorporated which entailed a change in orientation; that change was made using an assembly, so that any potential additional new Dragon orbits could be added in the future without modification of the model. The Earth orbit parameters such as albedo and Earth infrared flux were incorporated as time-varying values that change over the course of the orbit; despite being required in one of the ISS documents, this had not been done before by any previous payload. All parameters such as initial temperature, heater voltage, and location of the payload are defined based on the case definition. For one component, testing was performed in both air and vacuum; incorporating the air convection in a submodel that was
Industrial Process Identification and Control Design Step-test and Relay-experiment-based Methods
Liu, Tao
2012-01-01
Industrial Process Identification and Control Design is devoted to advanced identification and control methods for the operation of continuous-time processes both with and without time delay, in industrial and chemical engineering practice. The simple and practical step- or relay-feedback test is employed when applying the proposed identification techniques, which are classified in terms of common industrial process type: open-loop stable; integrating; and unstable, respectively. Correspondingly, control system design and tuning models that follow are presented for single-input-single-output processes. Furthermore, new two-degree-of-freedom control strategies and cascade control system design methods are explored with reference to independently-improving, set-point tracking and load disturbance rejection. Decoupling, multi-loop, and decentralized control techniques for the operation of multiple-input-multiple-output processes are also detailed. Perfect tracking of a desire output trajectory is realiz...
A novel single-step, multipoint calibration method for instrumented Lab-on-Chip systems
DEFF Research Database (Denmark)
Pfreundt, Andrea; Patou, François; Zulfiqar, Azeem
2014-01-01
Despite recent and substantial advances in biosensing, information and communication, and Lab-on-Chip (LoC) technologies, the success of Point-of-Care (PoC) diagnostics and monitoring systems is still challenged by stringent requirements for robustness, cost-effectiveness, and system integration....... The pitfalls of PoC system adoption can be addressed early in the system design phase. They require a multidisciplinary design approach supported by systems engineering tools and methods. Considering this, we here present both a model and an implementation of a simple and rapid calibration scheme...... for instrument-based PoC blood biomarker analysis systems. Motivated by the complexity of associating high-accuracy biosensing using silicon nanowire field effect transistors with ease of use for the PoC system user, we propose a novel one-step, multipoint calibration method for LoC-based systems. Our approach...
Characteristic analysis of laser isotope separation process by two-step photodissociation method
International Nuclear Information System (INIS)
Okamoto, Tsuyoshi; Suzuki, Atsuyuki; Kiyose, Ryohei
1981-01-01
A large number of laser isotope separation experiments have been performed actively in many countries. In this paper, the selective two-step photodissociation method is chosen and simultaneous nonlinear differential equations that express the separation process are solved directly by using computer. Predicted separation factors are investigated in relation to the incident pulse energy and the concentration of desired molecules. Furthermore, the concept of separative work is used to evaluate the results of separation for this method. It is shown from an example of numerical calculation that a very large separation factor can be obtained if the concentration of desired molecules is lowered and two laser pulses to be closely synchronized are not always required in operation for the photodissociation of molecules. (author)
Gu, Qiang; Chen, Ying; Chen, Dong; Zhang, Zeting
2018-01-01
This paper presents a method for preparing a super hydrophobic surface with a fast, simple, low-cost, one-step reaction by immersing copper alloy in an ethanol solution containing silver nitrate and myristic acid. The effects of reaction time, reaction temperature, reactant concentration and reaction time on the wettability of the material were studied. The surface wettability, appearance, chemical composition, durability and chemical stability of the prepared samples was measured by water contact angle (CA), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The results show that when the reaction time is only 10min, the surface WCA of the prepared material can reach 154.9. This study provides an effective method for the rapid preparation of stable super hydrophobic surfaces.
A two-step method for fast and reliable EUV mask metrology
Helfenstein, Patrick; Mochi, Iacopo; Rajendran, Rajeev; Yoshitake, Shusuke; Ekinci, Yasin
2017-03-01
One of the major obstacles towards the implementation of extreme ultraviolet lithography for upcoming technology nodes in semiconductor industry remains the realization of a fast and reliable detection methods patterned mask defects. We are developing a reflective EUV mask-scanning lensless imaging tool (RESCAN), installed at the Swiss Light Source synchrotron at the Paul Scherrer Institut. Our system is based on a two-step defect inspection method. In the first step, a low-resolution defect map is generated by die to die comparison of the diffraction patterns from areas with programmed defects, to those from areas that are known to be defect-free on our test sample. In a later stage, a die to database comparison will be implemented in which the measured diffraction patterns will be compared to those calculated directly from the mask layout. This Scattering Scanning Contrast Microscopy technique operates purely in the Fourier domain without the need to obtain the aerial image and, given a sufficient signal to noise ratio, defects are found in a fast and reliable way, albeit with a location accuracy limited by the spot size of the incident illumination. Having thus identified rough locations for the defects, a fine scan is carried out in the vicinity of these locations. Since our source delivers coherent illumination, we can use an iterative phase-retrieval method to reconstruct the aerial image of the scanned area with - in principle - diffraction-limited resolution without the need of an objective lens. Here, we will focus on the aerial image reconstruction technique and give a few examples to illustrate the capability of the method.
PHISICS/RELAP5-3D Adaptive Time-Step Method Demonstrated for the HTTR LOFC#1 Simulation
Energy Technology Data Exchange (ETDEWEB)
Baker, Robin Ivey [Idaho National Lab. (INL), Idaho Falls, ID (United States); Balestra, Paolo [Univ. of Rome (Italy); Strydom, Gerhard [Idaho National Lab. (INL), Idaho Falls, ID (United States)
2017-05-01
A collaborative effort between Japan Atomic Energy Agency (JAEA) and Idaho National Laboratory (INL) as part of the Civil Nuclear Energy Working Group is underway to model the high temperature engineering test reactor (HTTR) loss of forced cooling (LOFC) transient that was performed in December 2010. The coupled version of RELAP5-3D, a thermal fluids code, and PHISICS, a neutronics code, were used to model the transient. The focus of this report is to summarize the changes made to the PHISICS-RELAP5-3D code for implementing an adaptive time step methodology into the code for the first time, and to test it using the full HTTR PHISICS/RELAP5-3D model developed by JAEA and INL and the LOFC simulation. Various adaptive schemes are available based on flux or power convergence criteria that allow significantly larger time steps to be taken by the neutronics module. The report includes a description of the HTTR and the associated PHISICS/RELAP5-3D model test results as well as the University of Rome sub-contractor report documenting the adaptive time step theory and methodology implemented in PHISICS/RELAP5-3D. Two versions of the HTTR model were tested using 8 and 26 energy groups. It was found that most of the new adaptive methods lead to significant improvements in the LOFC simulation time required without significant accuracy penalties in the prediction of the fission power and the fuel temperature. In the best performing 8 group model scenarios, a LOFC simulation of 20 hours could be completed in real-time, or even less than real-time, compared with the previous version of the code that completed the same transient 3-8 times slower than real-time. A few of the user choice combinations between the methodologies available and the tolerance settings did however result in unacceptably high errors or insignificant gains in simulation time. The study is concluded with recommendations on which methods to use for this HTTR model. An important caveat is that these findings
2012-01-01
Nanochannel arrays were fabricated by the self-organized multi-electrolyte-step anodic aluminum oxide [AAO] method in this study. The anodization conditions used in the multi-electrolyte-step AAO method included a phosphoric acid solution as the electrolyte and an applied high voltage. There was a change in the phosphoric acid by the oxalic acid solution as the electrolyte and the applied low voltage. This method was used to produce self-organized nanochannel arrays with good regularity and circularity, meaning less power loss and processing time than with the multi-step AAO method. PMID:22333268
The Finite-Surface Method for incompressible flow: a step beyond staggered grid
Hokpunna, Arpiruk; Misaka, Takashi; Obayashi, Shigeru
2017-11-01
We present a newly developed higher-order finite surface method for the incompressible Navier-Stokes equations (NSE). This method defines the velocities as a surface-averaged value on the surfaces of the pressure cells. Consequently, the mass conservation on the pressure cells becomes an exact equation. The only things left to approximate is the momentum equation and the pressure at the new time step. At certain conditions, the exact mass conservation enables the explicit n-th order accurate NSE solver to be used with the pressure treatment that is two or four order less accurate without loosing the apparent convergence rate. This feature was not possible with finite volume of finite difference methods. We use Fourier analysis with a model spectrum to determine the condition and found that the range covers standard boundary layer flows. The formal convergence and the performance of the proposed scheme is compared with a sixth-order finite volume method. Finally, the accuracy and performance of the method is evaluated in turbulent channel flows. This work is partially funded by a research colloaboration from IFS, Tohoku university and ASEAN+3 funding scheme from CMUIC, Chiang Mai University.
Directory of Open Access Journals (Sweden)
Katz Mark M.
2016-01-01
Full Text Available The analysis of errors in the determination of thermal diffusivity of a typical semiconductor material - Germany, due to radiative energy transfer in the heated layer of material, under conditions consistent with the implementation of the method under the influence of the laser pulse on the surface of the collimated laser pulse of finite duration.
A coupled electro-thermal Discontinuous Galerkin method
Homsi, L.; Geuzaine, C.; Noels, L.
2017-11-01
This paper presents a Discontinuous Galerkin scheme in order to solve the nonlinear elliptic partial differential equations of coupled electro-thermal problems. In this paper we discuss the fundamental equations for the transport of electricity and heat, in terms of macroscopic variables such as temperature and electric potential. A fully coupled nonlinear weak formulation for electro-thermal problems is developed based on continuum mechanics equations expressed in terms of energetically conjugated pair of fluxes and fields gradients. The weak form can thus be formulated as a Discontinuous Galerkin method. The existence and uniqueness of the weak form solution are proved. The numerical properties of the nonlinear elliptic problems i.e., consistency and stability, are demonstrated under specific conditions, i.e. use of high enough stabilization parameter and at least quadratic polynomial approximations. Moreover the prior error estimates in the H1-norm and in the L2-norm are shown to be optimal in the mesh size with the polynomial approximation degree.
Synergistic degradation of konjac glucomannan by alkaline and thermal method.
Jin, Weiping; Mei, Ting; Wang, Yuntao; Xu, Wei; Li, Jing; Zhou, Bin; Li, Bin
2014-01-01
The application of konjac glucomannan (KGM) in the food industry is always limited by its high viscosity. Hereby, low-viscosity KGM was prepared by alkaline-thermal degradation method. This process was demonstrated by the changes of average molecular weight and a kinetic model was developed. The results revealed that high alkalinity and high temperature had a synergetic effect on degradation. The structure of hydrolysates was evaluated by periodate oxidation and their fluidly properties were researched by rheology measurements. The degradation was divided into two regimes. The rate of the first regime (within 1h) is higher than that of the second one (last 1h). It is found that alkaline hydrolysis and deacetylation have a synergistic effect on the degradation under high alkalinity (pH 9.2) and low temperature condition (25 °C). Finally, rheology parameters showed alkaline-thermal degradation is a promising way that can be applied in practice to degrade KGM. Copyright © 2013 Elsevier Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
Insun Jo
2015-05-01
Full Text Available Thermal transport in suspended graphene samples has been measured in prior works and this work with the use of a suspended electro-thermal micro-bridge method. These measurement results are analyzed here to evaluate and eliminate the errors caused by the extrinsic thermal contact resistance. It is noted that the room-temperature thermal resistance measured in a recent work increases linearly with the suspended length of the single-layer graphene samples synthesized by chemical vapor deposition (CVD, and that such a feature does not reveal the failure of Fourier’s law despite the increase in the reported apparent thermal conductivity with length. The re-analyzed apparent thermal conductivity of a single-layer CVD graphene sample reaches about 1680 ± 180 W m−1 K−1 at room temperature, which is close to the highest value reported for highly oriented pyrolytic graphite. In comparison, the apparent thermal conductivity values measured for two suspended exfoliated bi-layer graphene samples are about 880 ± 60 and 730 ± 60 Wm−1K−1 at room temperature, and approach that of the natural graphite source above room temperature. However, the low-temperature thermal conductivities of these suspended graphene samples are still considerably lower than the graphite values, with the peak thermal conductivities shifted to much higher temperatures. Analysis of the thermal conductivity data reveals that the low temperature behavior is dominated by phonon scattering by polymer residue instead of by the lateral boundary.
International Nuclear Information System (INIS)
Meuschke, R.E.; Boyd, C.H.
1989-01-01
This patent describes a method of limiting the movement of a thermal shield of a nuclear reactor. It comprises: machining at least four (4) pockets in upper portions of a thermal shield circumferentially about a core barrel of a nuclear reactor to receive key-wave inserts; tapping bolt holes in the pockets of the thermal shield to receive bolts; positioning key-wave inserts into the pockets of the thermal shield to be bolted in place with the bolt holes; machining dowel holes at least partially through the positioned key-way inserts and the thermal shield to receive dowel pins; positioning dowel pins in the dowel holes in the key-way insert and thermal shield to tangentially restrain movement of the thermal shield relative to the core barrel; sliding limiter keys into the key-way inserts and bolting the limiter keys to the core barrel to tangentially restrain movement of the thermal shield relative and the core barrel while allowing radial and axial movement of the thermal shield relative to the core barrel; machining dowel holes through the limiter key and at least partially through the core barrel to receive dowel pins; positioning dowel pins in the dowel holes in the limiter key and core barrel to restrain tangential movement of the thermal shield relative to the core barrel of the nuclear reactor
International Nuclear Information System (INIS)
Wołoszyn, Jerzy; Gołaś, Andrzej
2014-01-01
Highlights: • Paper propose a new methodology to sensitivity study of underground thermal storage. • Using MDF model and DOE technique significantly shorter of calculations time. • Calculation of one time step was equal to approximately 57 s. • Sensitivity study cover five thermo-physical parameters. • Conductivity of rock mass and grout material have a significant impact on efficiency. - Abstract: The aim of this study was to investigate the influence of selected parameters on the efficiency of underground thermal energy storage. In this paper, besides thermal conductivity, the effect of such parameters as specific heat, density of the rock mass, thermal conductivity and specific heat of grout material was investigated. Implementation of this objective requires the use of an efficient computational method. The aim of the research was achieved by using a new numerical model, Multi Degree of Freedom (MDF), as developed by the authors and Design of Experiment (DoE) techniques with a response surface. The presented methodology can significantly reduce the time that is needed for research and to determine the effect of various parameters on the efficiency of underground thermal energy storage. Preliminary results of the research confirmed that thermal conductivity of the rock mass has the greatest impact on the efficiency of underground thermal energy storage, and that other parameters also play quite significant role
SO2 oxidation catalyst model systems characterized by thermal methods
DEFF Research Database (Denmark)
Hatem, G; Eriksen, Kim Michael; Gaune-Escard, M
2002-01-01
The molten salts M2S2O7 and MHSO4, the binary molten salt Systems M2S2O7-MHSO4 and the molten salt-gas systems M2S2O7 V2O5 and M2S2O7-M2SO4 V2O5 (M = Na, K, Rb, Cs) in O-2, SO2 and At atmospheres have been investigated by thermal methods like calorimetry, Differential Enthalpic Analysis (DEA......) and Differential Scanning Calorimetry (DSC). Fundamental thermodynamic data like temperatures and molar heats of solid-solid transition and fusion, phase diagrams, heat capacities of solids and liquids, heat of mixing and heats of complex formation have been obtained and the results are discussed in relation...
Energy Technology Data Exchange (ETDEWEB)
Picolloto, A. M.; Mariucci, V. V. G.; Szpak, W.; Medina, A. N.; Baesso, M. L.; Astrath, N. G. C.; Astrath, F. B. G.; Bento, A. C., E-mail: acbento@uem.br [Departamento de Física, Grupo de Espectroscopia Fotoacústica e Fototérmica, Universidade Estadual de Maringá – UEM, Av. Colombo 5790, 87020-900 Maringá, Paraná (Brazil); Santos, A. D.; Moraes, J. C. S. [Departamento de Física e Química, Universidade Estadual Paulista Júlio de Mesquita Filho – UNESP, Av. Brasil 56, 15385-000 Ilha Solteira, SP (Brazil)
2013-11-21
The thermal wave method is applied for thermal properties measurement in fast endodontic cement (CER). This new formula is developed upon using Portland cement in gel and it was successfully tested in mice with good biocompatibility and stimulated mineralization. Recently, thermal expansion and setting time were measured, conferring to this material twice faster hardening than the well known Angelus Mineral trioxide aggregate (MTA) the feature of fast hardening (∼7 min) and with similar thermal expansion (∼12 μstrain/ °C). Therefore, it is important the knowledge of thermal properties like thermal diffusivity, conductivity, effusivity in order to match thermally the tissue environment upon its application in filling cavities of teeth. Photothermal radiometry technique based on Xe illumination was applied in CER disks 600 μm thick for heating, with prepared in four particle sizes (25, 38, 45, and 53) μm, which were added microemulsion gel with variation volumes (140, 150, 160, and 170) μl. The behavior of the thermal diffusivity CER disks shows linear decay for increase emulsion volume, and in contrast, thermal diffusivity increases with particles sizes. Aiming to compare to MTA, thermal properties of CER were averaged to get the figure of merit for thermal diffusivity as (44.2 ± 3.6) × 10{sup −3} cm{sup 2}/s, for thermal conductivity (228 ± 32) mW/cm K, the thermal effusivity (1.09 ± 0.06) W s{sup 0.5}/cm{sup 2} K and volume heat capacity (5.2 ± 0.7) J/cm{sup 3} K, which are in excellent agreement with results of a disk prepared from commercial MTA-Angelus (grain size < 10 μm using 57 μl of distilled water)
Picolloto, A. M.; Mariucci, V. V. G.; Szpak, W.; Medina, A. N.; Baesso, M. L.; Astrath, N. G. C.; Astrath, F. B. G.; Santos, A. D.; Moraes, J. C. S.; Bento, A. C.
2013-11-01
The thermal wave method is applied for thermal properties measurement in fast endodontic cement (CER). This new formula is developed upon using Portland cement in gel and it was successfully tested in mice with good biocompatibility and stimulated mineralization. Recently, thermal expansion and setting time were measured, conferring to this material twice faster hardening than the well known Angelus Mineral trioxide aggregate (MTA) the feature of fast hardening (˜7 min) and with similar thermal expansion (˜12 μstrain/ °C). Therefore, it is important the knowledge of thermal properties like thermal diffusivity, conductivity, effusivity in order to match thermally the tissue environment upon its application in filling cavities of teeth. Photothermal radiometry technique based on Xe illumination was applied in CER disks 600 μm thick for heating, with prepared in four particle sizes (25, 38, 45, and 53) μm, which were added microemulsion gel with variation volumes (140, 150, 160, and 170) μl. The behavior of the thermal diffusivity CER disks shows linear decay for increase emulsion volume, and in contrast, thermal diffusivity increases with particles sizes. Aiming to compare to MTA, thermal properties of CER were averaged to get the figure of merit for thermal diffusivity as (44.2 ± 3.6) × 10-3 cm2/s, for thermal conductivity (228 ± 32) mW/cm K, the thermal effusivity (1.09 ± 0.06) W s0.5/cm2 K and volume heat capacity (5.2 ± 0.7) J/cm3 K, which are in excellent agreement with results of a disk prepared from commercial MTA-Angelus (grain size < 10 μm using 57 μl of distilled water).
Directory of Open Access Journals (Sweden)
Cheng Qian
2017-10-01
Full Text Available By solving the problem of very long test time on reliability qualification for Light-emitting Diode (LED products, the accelerated degradation test with a thermal overstress at a proper range is regarded as a promising and effective approach. For a comprehensive survey of the application of step-stress accelerated degradation test (SSADT in LEDs, the thermal, photometric, and colorimetric properties of two types of LED chip scale packages (CSPs, i.e., 4000 °K and 5000 °K samples each of which was driven by two different levels of currents (i.e., 120 mA and 350 mA, respectively, were investigated under an increasing temperature from 55 °C to 150 °C and a systemic study of driving current effect on the SSADT results were also reported in this paper. During SSADT, junction temperatures of the test samples have a positive relationship with their driving currents. However, the temperature-voltage curve, which represents the thermal resistance property of the test samples, does not show significant variance as long as the driving current is no more than the sample’s rated current. But when the test sample is tested under an overdrive current, its temperature-voltage curve is observed as obviously shifted to the left when compared to that before SSADT. Similar overdrive current affected the degradation scenario is also found in the attenuation of Spectral Power Distributions (SPDs of the test samples. As used in the reliability qualification, SSADT provides explicit scenes on color shift and correlated color temperature (CCT depreciation of the test samples, but not on lumen maintenance depreciation. It is also proved that the varying rates of the color shift and CCT depreciation failures can be effectively accelerated with an increase of the driving current, for instance, from 120 mA to 350 mA. For these reasons, SSADT is considered as a suitable accelerated test method for qualifying these two failure modes of LED CSPs.
Fast Measurement of Methanol Concentration in Ionic Liquids by Potential Step Method
Hainstock, Michael L.; Tang, Yijun
2015-01-01
The development of direct methanol fuel cells required the attention to the electrolyte. A good electrolyte should not only be ionic conductive but also be crossover resistant. Ionic liquids could be a promising electrolyte for fuel cells. Monitoring methanol was critical in several locations in a direct methanol fuel cell. Conductivity could be used to monitor the methanol content in ionic liquids. The conductivity of 1-butyl-3-methylimidazolium tetrafluoroborate had a linear relationship with the methanol concentration. However, the conductivity was significantly affected by the moisture or water content in the ionic liquid. On the contrary, potential step could be used in sensing methanol in ionic liquids. This method was not affected by the water content. The sampling current at a properly selected sampling time was proportional to the concentration of methanol in 1-butyl-3-methylimidazolium tetrafluoroborate. The linearity still stood even when there was 2.4 M water present in the ionic liquid. PMID:25802522
Fast Measurement of Methanol Concentration in Ionic Liquids by Potential Step Method
Directory of Open Access Journals (Sweden)
Michael L. Hainstock
2015-01-01
Full Text Available The development of direct methanol fuel cells required the attention to the electrolyte. A good electrolyte should not only be ionic conductive but also be crossover resistant. Ionic liquids could be a promising electrolyte for fuel cells. Monitoring methanol was critical in several locations in a direct methanol fuel cell. Conductivity could be used to monitor the methanol content in ionic liquids. The conductivity of 1-butyl-3-methylimidazolium tetrafluoroborate had a linear relationship with the methanol concentration. However, the conductivity was significantly affected by the moisture or water content in the ionic liquid. On the contrary, potential step could be used in sensing methanol in ionic liquids. This method was not affected by the water content. The sampling current at a properly selected sampling time was proportional to the concentration of methanol in 1-butyl-3-methylimidazolium tetrafluoroborate. The linearity still stood even when there was 2.4 M water present in the ionic liquid.
Suleimanov, Yury V; Green, William H
2015-09-08
We present a simple protocol which allows fully automated discovery of elementary chemical reaction steps using in cooperation double- and single-ended transition-state optimization algorithms--the freezing string and Berny optimization methods, respectively. To demonstrate the utility of the proposed approach, the reactivity of several single-molecule systems of combustion and atmospheric chemistry importance is investigated. The proposed algorithm allowed us to detect without any human intervention not only "known" reaction pathways, manually detected in the previous studies, but also new, previously "unknown", reaction pathways which involve significant atom rearrangements. We believe that applying such a systematic approach to elementary reaction path finding will greatly accelerate the discovery of new chemistry and will lead to more accurate computer simulations of various chemical processes.
Comments on Thermal Physical Properties Testing Methods of Phase Change Materials
Directory of Open Access Journals (Sweden)
Jingchao Xie
2013-01-01
Full Text Available There is no standard testing method of the thermal physical properties of phase change materials (PCM. This paper has shown advancements in this field. Developments and achievements in thermal physical properties testing methods of PCM were commented, including differential scanning calorimetry, T-history measurement, the water bath method, and differential thermal analysis. Testing principles, advantages and disadvantages, and important points for attention of each method were discussed. A foundation for standardized testing methods for PCM was made.
Single-step blood direct PCR: A robust and rapid method to diagnose triplet repeat disorders.
Singh, Inder; Swarup, Vishnu; Shakya, Sunil; Goyal, Vinay; Faruq, Mohammed; Srivastava, Achal Kumar
2017-08-15
DNA extraction prior to polymerase chain reaction (PCR) amplification in genetic diagnoses of triplet repeat disorders (TRDs) is tedious and labour-intensive and has the limitations of sample contamination with foreign DNA, including that from preceding samples. Therefore, we aimed to develop a rapid, robust, and cost-effective method for expeditious genetic investigation of TRDs from whole blood as a DNA template. Peripheral blood samples were collected from 70 clinically suspected patients of progressive ataxia. The conventional method using genomic DNA and single-step Blood-Direct PCR (BD-PCR) method with just 2μl of whole blood sample were tested to amplify triplet repeat expansion in genes related to spinocerebellar ataxia (SCA) types 1, 2, 3, 12 and Friedreich's ataxia (FRDA). Post-PCR, the allele sizes were mapped and repeat numbers were calculated using GeneMapper and macros run in Microsoft Excel programmes. Successful amplification of target regions was achieved in all samples by both methods. The frequency of the normal and mutated allele was concordant between both methods, diagnosing 37% positive for a mutation in either of the candidate genes. The BD-PCR resulted in higher intensities of product peaks of normal and pathogenic alleles. The nearly-accurate sizing of the normal and expanded allele was achieved in a shorter time (4-5h), without DNA extraction and any risk of cross contamination, which suggests the BD-PCR to be a reliable, inexpensive, and rapid method to confirm TRDs. This technique can be introduced in routine diagnostic procedures of other tandem repeat disorders. Copyright © 2017 Elsevier B.V. All rights reserved.
In situ thermal properties characterization using frequential methods
Energy Technology Data Exchange (ETDEWEB)
Carpentier, O.; Defer, D.; Antczak, E.; Chauchois, A.; Duthoit, B. [Laboratoire dArtois de Mecanique Thermique Instrumentation (LAMTI), FSA Universite dArtois, Technoparc Futura, 62400 Bethune (France)
2008-07-01
In numerous fields, especially that of geothermal energy, we need to know about the thermal behaviour of the soil now that the monitoring of renewable forms of energy is an ecological, economic and scientific issue. Thus heat from the soil is widely used for air-conditioning systems in buildings both in Canada and in the Scandinavian countries, and it is spreading. The effectiveness of this technique is based on the soils calorific potential and its thermophysical properties which will define the quality of the exchanges between the soil and a heat transfer fluid. This article puts forward a method to be used for the in situ thermophysical characterisation of a soil. It is based upon measuring the heat exchanges on the surface of the soil and on measuring a temperature a few centimetres below the surface. The system is light, inexpensive, well-suited to the taking of measurements in situ without the sensors used introducing any disturbance into the heat exchanges. Whereas the majority of methods require excitation, the one presented here is passive and exploits natural signals. Based upon a few hours of recording, the natural signals allow us to identify the soils thermophysical properties continuously. The identification is based upon frequency methods the quality of which can be seen when the thermophysical properties are injected into a model with finite elements by means of a comparison of the temperatures modelled and those actually measured on site. (author)
Studies on compatibility of energetic materials by thermal methods
Directory of Open Access Journals (Sweden)
Maria Alice Carvalho Mazzeu
2010-04-01
Full Text Available The chemical compatibility of explosives, pyrotechnics and propellants with those materials is studied to evaluate potential hazards when in contact with other materials during production, storage and handling. Compatibility can be studied by several thermal methods as DSC (differential scanning calorimetry, TG (Thermogravimetry, VST (Vacuum stability test and others. The test methods and well defined criteria are the most important elements when a compatibility study is being accomplished. In this paper, the compatibility of two very important high explosives used in ammunition, RDX (Cyclo-1,3,5-trimethylene-2,4,6-trinitramine and HMX (Cyclotetramethylene tetranitramine was studied with the materials: fluoroelastomer (Viton and powdered aluminum (Al, using DSC and VST methods. The criteria to judge the compatibility between materials is based on a standardization agreement (STANAG 4147, 2001, and the final conclusion is that explosives and this materials are compatible, but in DSC it was observed that the peak of decomposition temperature of the admixture of RDX with Al decreased in 3º C and another peak appeared after the decomposition peak.
A two-step method for the extraction of high-quality RNA from endoscopic biopsies.
Wex, Thomas; Treiber, Gerhard; Lendeckel, Uwe; Malfertheiner, Peter
2003-08-01
The use of molecular techniques such as quantitative RT-PCR depends on the quality of cellular RNA. In particular, RNA extraction from endoscopic biopsies is difficult with respect to yield, and especially integrity. Endoscopic biopsies taken from the gastric antrum, corpus and duodenum were subjected to various RNA extraction protocols, and the RNA was used for quantitative RT-PCR. The subsequent use of two methods, (i) a phenol/chloroform extraction and (ii) a column-based extraction method, resulted in a yield of 4.5 microg total RNA per biopsy with reliable quality in 80% of samples. The quantitative RT-PCR analysis revealed that only RNA samples that clearly show both 18S- and 28S-RNA bands in agarose gel electrophoresis were suitable for quantitative RT-PCR as shown by expression of corpus-specific pepsinogen C-mRNA and the duodenum-specific multi-drug resistance protein-1 (mdr-1)-mRNA. In partially degraded RNA, pepsinogen C, mdr-1, or beta-actin mRNAs were still detectable, but the quantitative determination gave inconsistent data. The two-step method described here is a suitable option for extracting high-quality RNA from endoscopic biopsies when other standard protocols fail.
Adsorption desalination: An emerging low-cost thermal desalination method
Ng, K. C.
2013-01-01
Desalination, other than the natural water cycle, is hailed as the panacea to alleviate the problems of fresh water shortage in many water stressed countries. However, the main drawback of conventional desalination methods is that they are energy intensive. In many instances, they consumed electricity, chemicals for pre- and post-treatment of water. For each kWh of energy consumed, there is an unavoidable emission of Carbon Dioxide (CO2) at the power stations as well as the discharge of chemically-laden brine into the environment. Thus, there is a motivation to find new direction or methods of desalination that consumed less chemicals, thermal energy and electricity.This paper describes an emerging and yet low cost method of desalination that employs only low-temperature waste heat, which is available in abundance from either the renewable energy sources or exhaust of industrial processes. With only one heat input, the Adsorption Desalination (AD) cycle produces two useful effects, i.e., high grade potable water and cooling. In this article, a brief literature review, the theoretical framework for adsorption thermodynamics, a lumped-parameter model and the experimental tests for a wide range of operational conditions on the basic and the hybrid AD cycles are discussed. Predictions from the model are validated with measured performances from two pilot plants, i.e., a basic AD and the advanced AD cycles. The energetic efficiency of AD cycles has been compared against the conventional desalination methods. Owing to the unique features of AD cycle, i.e., the simultaneous production of dual useful effects, it is proposed that the life cycle cost (LCC) of AD is evaluated against the LCC of combined machines that are needed to deliver the same quantities of useful effects using a unified unit of $/MWh. In closing, an ideal desalination system with zero emission of CO2 is presented where geo-thermal heat is employed for powering a temperature-cascaded cogeneration plant.
Nakanishi, Kouichi; Kogure, Akinori; Kuwana, Ritsuko; Takamatsu, Hiromu; Ito, Kiyoshi
2017-01-01
Differences in the physical properties of individual cells cannot be evaluated with conventional experimental methods that are used to study groups of cells obtained from pure cultures. To examine the differences in the thermal tolerance of individual cells that are genetically identical, a method is needed to measure the thermal energy required to kill single cells. We developed a scanning thermal microscopy (SThM) system and measured the thermal conductivity of various bacterial cells, for example, spore formeing Bacillus genus and non spore-forming bacteria such as Escherichia coli. The thermal conductivity of vegetative cells (0.61 to 0.75 W/m・K) was found to be higher than that of spores (0.29 to 0.45 W/m・K). Furthermore the newly developed method enables us to estimate the thermal energy needed to kill individual cells or spores. We believe that this method can estimate the thermal energy required to achieve the cell for sterilization by heating.
Thermal-mechanical analysis for a viscoelastoplastic model by finite element method
International Nuclear Information System (INIS)
Vaz, L.E.; Vaz, R.O.E.
1989-01-01
The aim of this work is to present a formulation and a computer program which permits the study of problems involving the influence of the temperature on the mechanical behavior of a viscoelastoplastic material. The thermo-mechanical analysis is carried out in two steps. The first step performs the transient thermal analysis. The second step uses the time-history of the temperature distribution that results on the first step, for the transient stress analysis. The program treat plane and axi-symmetrical problems. As an application of the formulation the quenching of a cylinder of metal is examined. (author)
Numerical simulation of flow over backward-facing step using parallel multi-block compact method
International Nuclear Information System (INIS)
Esfahanian, V.; Torabi, F.; Khajavi Rad, A.; Babaee, H.
2005-01-01
In this study the accurate location of separation and reattachment points in the flow over backward-facing step have been determined for 100< Re<800. Two-dimensional steady incompressible Navier-Stokes equations have been solved using stream function-vorticity formulation, along with fourth-order upwind compact finite difference method. Considering high computational cost of the compact method, a parallel multi-block algorithm has been implemented to reduce the execution time. According to this scheme the main domain is decomposed into several equal size sub-blocks which each will be solved by different processors independently. Each node will receive its boundary values from adjacent processors during iteration by introducing the concept of 'ghost points'. Parallelizing has been achieved through a Beowulf system which contains a cluster of PCs with distributed memory. MPI library has been used for passing messages between various nodes. In order to verify the obtained results, the loci of separation and reattachment points have been compared with other experimental and numerical results. Finally, speed up and performance of parallel algorithm have been examined. (author)
Improved adhesion of superhydrophobic layer on metal surfaces via one step spraying method
Directory of Open Access Journals (Sweden)
Wael I. El Dessouky
2017-03-01
Full Text Available Superhydrophobic metal substrates have been fabricated by a simple spraying method. The processes of decreasing surface free energy and increasing surface roughness have been accomplished in one step via the addition of functionalized silica (silica nano particles with octyltriethoxysilane to adhesive polymer. The method is simple, cost-effective and can be applied on the large industrial scale. Scanning electron microscopy (SEM was used for surface morphology analysis, showing the roughness produced by surface treatment. The wettability of the micro-nano silica film varied from hydrophilicity (water contact angle 88° to superhydrophobicity (water contact angle 156.9°, while sliding contact angles dramatically decreased (<5° by adding Functionalized silica and/or adhesive polymer. Roughness increased with silica increment which improves the wettability. The coatings were electrochemically characterized by electrochemical impedance spectroscopy (EIS and Tafel polarization curves; it was found that both systems had good performance against corrosion in 3.5% sodium chloride solution. Furthermore, the stability of the coated layer on copper substrate was investigated.
DEFF Research Database (Denmark)
Zajas, Jan Jakub; Heiselberg, Per
2013-01-01
Determination of thermal conductivity of construction materials is essential to estimate their insulation capabilities. In most cases, homogenous materials are used and well developed methods exist for measurements of their thermal conductivity. The task becomes more challenging when dealing...... by scanning them point by point and determining the thermal conductivity as a function of the spatial dimensions. The method proves to be repeatable and of reasonable accuracy and can be used to determine the local thermal properties on a scale of millimeters. In this study, the method was successfully...... applied to create a map of thermal conductivity of a functionally graded material sample....
Application of Hot-wire Method for Measuring Thermal Conductivity of Fine Ceramics
Directory of Open Access Journals (Sweden)
Shangxi WANG
2016-11-01
Full Text Available Ceramic substrate is preferred in high density packaging due to its high electrical resistivity and moderate expansion coefficient. The thermal conductivity is a key parameter for packaging substrates. There are two common methods to measure the thermal conductivity, which are the hot-wire method and the laser-flash method. Usually, the thermal conductivities of porcelain is low and meet the measurement range of hot-wire method, and the measured value by hot-wire method has little difference with that by laser-flash method. In recent years, with the requirement of high-powered LED lighting, some kinds of ceramic substrates with good thermal conductivity have been developed and their thermal conductivity always measured by the means of laser flash method, which needs expensive instrument. In this paper, in order to detect the thermal conductivity of fine ceramic with convenience and low cost, the feasibility of replacing the laser flash method with hot wire method to measure thermal conductivity of ceramic composites was studied. The experiment results showed that the thermal conductivity value of fine ceramics measured by the hot-wire method is severely lower than that by the laser-flash method. However, there is a positive relationship between them. It is possible to measure the thermal conductivity of fine ceramic workpiece instantly by hot-wire method via a correction formula.DOI: http://dx.doi.org/10.5755/j01.ms.22.4.12543
Thermal dynamics of thermoelectric phenomena from frequency resolved methods
Directory of Open Access Journals (Sweden)
J. García-Cañadas
2016-03-01
Full Text Available Understanding the dynamics of thermoelectric (TE phenomena is important for the detailed knowledge of the operation of TE materials and devices. By analyzing the impedance response of both a single TE element and a TE device under suspended conditions, we provide new insights into the thermal dynamics of these systems. The analysis is performed employing parameters such as the thermal penetration depth, the characteristic thermal diffusion frequency and the thermal diffusion time. It is shown that in both systems the dynamics of the thermoelectric response is governed by how the Peltier heat production/absorption at the junctions evolves. In a single thermoelement, at high frequencies the thermal waves diffuse semi-infinitely from the junctions towards the half-length. When the frequency is reduced, the thermal waves can penetrate further and eventually reach the half-length where they start to cancel each other and further penetration is blocked. In the case of a TE module, semi-infinite thermal diffusion along the thickness of the ceramic layers occurs at the highest frequencies. As the frequency is decreased, heat storage in the ceramics becomes dominant and starts to compete with the diffusion of the thermal waves towards the half-length of the thermoelements. Finally, the cancellation of the waves occurs at the lowest frequencies. It is demonstrated that the analysis is able to identify and separate the different physical processes and to provide a detailed understanding of the dynamics of different thermoelectric effects.
Thermal analysis methods in the characterization of photocatalytic titania precursors
Czech Academy of Sciences Publication Activity Database
Pulišová, Petra; Večerníková, Eva; Maříková, Monika; Balek, V.; Boháček, Jaroslav; Šubrt, Jan
2012-01-01
Roč. 108, č. 2 (2012), s. 489-492 ISSN 1388-6150 R&D Projects: GA MŠk 1M0577 Institutional research plan: CEZ:AV0Z40320502 Keywords : differential thermal analysis * thermogravimetry * emanation thermal analysis * titanium dioxide * photocatalyst Subject RIV: CA - Inorganic Chemistry Impact factor: 1.982, year: 2012
International Nuclear Information System (INIS)
Sereinig, W.; Gross, F.
1982-01-01
An apparatus for measuring the integral thermal expansions at cryogenic temperatures is described. The thermal expansions are given for a number of commercial epoxy resins, commercial polyester resins and inorganic cements. A method to reduce the thermal expansion of the resins by the use of quartz powder fillers is reported. (author)
A dynamically adaptive lattice Boltzmann method for thermal convection problems
Directory of Open Access Journals (Sweden)
Feldhusen Kai
2016-12-01
Full Text Available Utilizing the Boussinesq approximation, a double-population incompressible thermal lattice Boltzmann method (LBM for forced and natural convection in two and three space dimensions is developed and validated. A block-structured dynamic adaptive mesh refinement (AMR procedure tailored for the LBM is applied to enable computationally efficient simulations of moderate to high Rayleigh number flows which are characterized by a large scale disparity in boundary layers and free stream flow. As test cases, the analytically accessible problem of a two-dimensional (2D forced convection flow through two porous plates and the non-Cartesian configuration of a heated rotating cylinder are considered. The objective of the latter is to advance the boundary conditions for an accurate treatment of curved boundaries and to demonstrate the effect on the solution. The effectiveness of the overall approach is demonstrated for the natural convection benchmark of a 2D cavity with differentially heated walls at Rayleigh numbers from 103 up to 108. To demonstrate the benefit of the employed AMR procedure for three-dimensional (3D problems, results from the natural convection in a cubic cavity at Rayleigh numbers from 103 up to 105 are compared with benchmark results.
Thermally-enhanced oil recovery method and apparatus
Stahl, Charles R.; Gibson, Michael A.; Knudsen, Christian W.
1987-01-01
A thermally-enhanced oil recovery method and apparatus for exploiting deep well reservoirs utilizes electric downhole steam generators to provide supplemental heat to generate high quality steam from hot pressurized water which is heated at the surface. A downhole electric heater placed within a well bore for local heating of the pressurized liquid water into steam is powered by electricity from the above-ground gas turbine-driven electric generators fueled by any clean fuel such as natural gas, distillate or some crude oils, or may come from the field being stimulated. Heat recovered from the turbine exhaust is used to provide the hot pressurized water. Electrical power may be cogenerated and sold to an electric utility to provide immediate cash flow and improved economics. During the cogeneration period (no electrical power to some or all of the downhole units), the oil field can continue to be stimulated by injecting hot pressurized water, which will flash into lower quality steam at reservoir conditions. The heater includes electrical heating elements supplied with three-phase alternating current or direct current. The injection fluid flows through the heater elements to generate high quality steam to exit at the bottom of the heater assembly into the reservoir. The injection tube is closed at the bottom and has radial orifices for expanding the injection fluid to reservoir pressure.
The furan microsolvation blind challenge for quantum chemical methods: First steps
Gottschalk, Hannes C.; Poblotzki, Anja; Suhm, Martin A.; Al-Mogren, Muneerah M.; Antony, Jens; Auer, Alexander A.; Baptista, Leonardo; Benoit, David M.; Bistoni, Giovanni; Bohle, Fabian; Dahmani, Rahma; Firaha, Dzmitry; Grimme, Stefan; Hansen, Andreas; Harding, Michael E.; Hochlaf, Majdi; Holzer, Christof; Jansen, Georg; Klopper, Wim; Kopp, Wassja A.; Kröger, Leif C.; Leonhard, Kai; Mouhib, Halima; Neese, Frank; Pereira, Max N.; Ulusoy, Inga S.; Wuttke, Axel; Mata, Ricardo A.
2018-01-01
Herein we present the results of a blind challenge to quantum chemical methods in the calculation of dimerization preferences in the low temperature gas phase. The target of study was the first step of the microsolvation of furan, 2-methylfuran and 2,5-dimethylfuran with methanol. The dimers were investigated through IR spectroscopy of a supersonic jet expansion. From the measured bands, it was possible to identify a persistent hydrogen bonding OH-O motif in the predominant species. From the presence of another band, which can be attributed to an OH-π interaction, we were able to assert that the energy gap between the two types of dimers should be less than or close to 1 kJ/mol across the series. These values served as a first evaluation ruler for the 12 entries featured in the challenge. A tentative stricter evaluation of the challenge results is also carried out, combining theoretical and experimental results in order to define a smaller error bar. The process was carried out in a double-blind fashion, with both theory and experimental groups unaware of the results on the other side, with the exception of the 2,5-dimethylfuran system which was featured in an earlier publication.
A one pot, one step, precision cloning method with high throughput capability.
Directory of Open Access Journals (Sweden)
Carola Engler
Full Text Available Current cloning technologies based on site-specific recombination are efficient, simple to use, and flexible, but have the drawback of leaving recombination site sequences in the final construct, adding an extra 8 to 13 amino acids to the expressed protein. We have devised a simple and rapid subcloning strategy to transfer any DNA fragment of interest from an entry clone into an expression vector, without this shortcoming. The strategy is based on the use of type IIs restriction enzymes, which cut outside of their recognition sequence. With proper design of the cleavage sites, two fragments cut by type IIs restriction enzymes can be ligated into a product lacking the original restriction site. Based on this property, a cloning strategy called 'Golden Gate' cloning was devised that allows to obtain in one tube and one step close to one hundred percent correct recombinant plasmids after just a 5 minute restriction-ligation. This method is therefore as efficient as currently used recombination-based cloning technologies but yields recombinant plasmids that do not contain unwanted sequences in the final construct, thus providing precision for this fundamental process of genetic manipulation.
A Novel Two-Step Method for Fabricating Silver Plating Cotton Fabrics
Directory of Open Access Journals (Sweden)
Hao Liu
2016-01-01
Full Text Available A novel two-step method was presented for fabricating silver plating cotton fabrics (SPCFs with high electrical conductivity and excellent washing fastness. First, polydopamine (PDA film was coated on the surface of cotton fabrics by in situ polymerization of dopamine, the silver ions in silver nitrate solution were reduced by the catechol groups of polydopamine, and silver nanoparticles were combined with polydopamine by covalent bond on the surface of cotton fabrics. Second, silver ions were reduced by glucose, and silver plating was coated on the surface. Subsequently, the properties of SPCFs were characterized by field emission scanning electron microscopy (FESEM, X-ray photoelectron spectroscopy (XPS and thermogravimetric analysis (TGA, and so forth. With the increasing of silver-ammonia solution concentration or dopamine concentration, the surface resistivity of SPCFs decreases and gradually stabilized. The surface resistivity of the SPCFs can reach 0.12±0.02 Ω, and electromagnetic shielding effectiveness (ESE of the SPCFs can reach 58.5±4.5 dB. Conductive fabrics have wide application prospect in many of fields, such as antibacterial, intelligent textiles, smart garments, electromagnetic shielding, and flexible sensors.
Peterson, Molly S M; Bouwman, Jason; Chen, Aiqing; Deutsch, Miriam
2007-02-01
Two methods for preparing polycrystalline silver shells on colloidal silica spheres are reported. These do not include the use of organic ligands or metal seeding steps and are based on the Tollen's process for silvering glass. Reaction parameters such as temperature and reactant concentrations are adjusted to slow the reaction kinetics, which we find leads to preferential silver growth on the spheres. The resulting shells are polycrystalline and granular, showing highly uniform sphere coverage. Surface morphologies range from sparsely interconnected grains for shells approximately 20 nm thick, to complete (yet porous) shells of interconnected silver clusters which are up to approximately 140 nm in thickness. The extinction spectra of the core-shell materials are markedly different from those of smooth continuous shells, showing clear evidence that the granular shell geometry influences the plasmon resonance of the composite system. Spheres coated with shells 20-40 nm thick are also suitable for colloidal crystallization. Monolayers of self-assembled spheres with long-range ordering are demonstrated.
A multi-step method for preparation of porcine small intestinal submucosa (SIS).
Luo, Jing-Cong; Chen, Wei; Chen, Xiao-He; Qin, Ting-Wu; Huang, Yong-Can; Xie, Hui-Qi; Li, Xiu-Qun; Qian, Zhi-Yong; Yang, Zhi-Ming
2011-01-01
Porcine small intestinal submucosa (SIS) has been widely used in repairing various tissues and organs. Despite this, some SIS products have the capacity to cause variable inflammatory responses after implantation resulting in severe adverse effects due to porcine cell existence. In this study, we described a multi-step method including mechanical disassociation, degrease, enzyme digestion, detergent treatment, freeze-drying and sterilization by irradiation for preparation of SIS. The efficacy of acellularization was evaluated by histological observation and the content of porcine immunoreceptor DAP12 gene. The change of growth factors contents within SIS accompanying with decellularization was quantitatively assessed by ELISA. Inflammatory reaction of SIS implanted subcutaneously in a rat was investigated. The histological examination revealed no remaining cells after enzyme digestion. Moreover, qPCR analysis demonstrated that the content of a porcine immunoreceptor gene DAP12 DNA in final SIS product (SISv) was only 1.05% of that in SIS samples (SISi) prepared by mechanical disassociation. Degrease with methanol/chloroform dramatically reduced the contents of VEGF, b-FGF, TGF-β, and TNF-α within SISii, but further treatment could not significantly reduced the contents of growth factors. SIS implanted into rats showed that inflammatory cells was more accumulated surrounded to SISi at 1, and 2 weeks, but reduced in SISv samples. The degree of inflammatory reaction for SISv was significantly less than that of SISi. Copyright © 2010 Elsevier Ltd. All rights reserved.
Ammonia-mediated Method for One-step and Surfactant-free Synthesis of Magnetite Nanoparticles
Directory of Open Access Journals (Sweden)
M. Mansournia
2015-10-01
Full Text Available Magnetite (Fe3O4 nanoparticles have been successfully prepared by a novel one-step and surfactant-free approach utilizing ferrous ion, as a single iron source. In this manner, the reaction occurs between two aqueous solutions via the spontaneous transfer of ammonia gas from one to another in room temperature. No ferric source or oxidizing specie, oxidation controlling and capping agents are needed and the method is suited for large-scale preparation. The effects of reaction conditions on the formation of Fe3O4 were investigated using powder X-ray diffraction (XRD, Fourier transformation infrared spectroscopy (FT-IR and scanning electron microscopy (SEM techniques. The results have demonstrated that the pure and single phase magnetite nanoparticles were synthesized at the final pH values higher than 8. Accordingly, the formation mechanism of these nanostructures is proposed. Moreover, the vibrating sample magnetometry (VSM measurements of the as-synthesized nanoparticles show their room temperature superparamagnetic characteristic with a typical saturation magnetization of 51 emug−1.
Kranz, David William
2010-01-01
The goal of this research project was be to compare and contrast the selected materials used in step measurements during pre-fits of thermal protection system tiles and to compare and contrast the accuracy of measurements made using these selected materials. The reasoning for conducting this test was to obtain a clearer understanding to which of these materials may yield the highest accuracy rate of exacting measurements in comparison to the completed tile bond. These results in turn will be presented to United Space Alliance and Boeing North America for their own analysis and determination. Aerospace structures operate under extreme thermal environments. Hot external aerothermal environments in high Mach number flights lead to high structural temperatures. The differences between tile heights from one to another are very critical during these high Mach reentries. The Space Shuttle Thermal Protection System is a very delicate and highly calculated system. The thermal tiles on the ship are measured to within an accuracy of .001 of an inch. The accuracy of these tile measurements is critical to a successful reentry of an orbiter. This is why it is necessary to find the most accurate method for measuring the height of each tile in comparison to each of the other tiles. The test results indicated that there were indeed differences in the selected materials used in step measurements during prefits of Thermal Protection System Tiles and that Bees' Wax yielded a higher rate of accuracy when compared to the baseline test. In addition, testing for experience level in accuracy yielded no evidence of difference to be found. Lastly the use of the Trammel tool over the Shim Pack yielded variable difference for those tests.
Energy Technology Data Exchange (ETDEWEB)
Jensen, C. [GRESPI, Multiscale Thermophysics Lab., Université de Reims Champagne-Ardenne URCA, Moulin de la Housse BP 1039, Reims 51687 (France); Department of Mechanical and Aerospace Engineering, Utah State University, Logan, Utah 84322 (United States); Chirtoc, M.; Horny, N.; Antoniow, J. S.; Pron, H. [GRESPI, Multiscale Thermophysics Lab., Université de Reims Champagne-Ardenne URCA, Moulin de la Housse BP 1039, Reims 51687 (France); Ban, H. [Department of Mechanical and Aerospace Engineering, Utah State University, Logan, Utah 84322 (United States)
2013-10-07
Using complementary thermal wave methods, the irradiation damaged region of zirconium carbide (ZrC) is characterized by quantifiably profiling the thermophysical property degradation. The ZrC sample was irradiated by a 2.6 MeV proton beam at 600 °C to a dose of 1.75 displacements per atom. Spatial scanning techniques including scanning thermal microscopy (SThM), lock-in infrared thermography (lock-in IRT), and photothermal radiometry (PTR) were used to directly map the in-depth profile of thermal conductivity on a cross section of the ZrC sample. The advantages and limitations of each system are discussed and compared, finding consistent results from all techniques. SThM provides the best resolution finding a very uniform thermal conductivity envelope in the damaged region measuring ∼52 ± 2 μm deep. Frequency-based scanning PTR provides quantification of the thermal parameters of the sample using the SThM measured profile to provide validation of a heating model. Measured irradiated and virgin thermal conductivities are found to be 11.9 ± 0.5 W m{sup −1} K{sup −1} and 26.7 ±1 W m{sup −1} K{sup −1}, respectively. A thermal resistance evidenced in the frequency spectra of the PTR results was calculated to be (1.58 ± 0.1) × 10{sup −6} m{sup 2} K W{sup −1}. The measured thermal conductivity values compare well with the thermal conductivity extracted from the SThM calibrated signal and the spatially scanned PTR. Combined spatial and frequency scanning techniques are shown to provide a valuable, complementary combination for thermal property characterization of proton-irradiated ZrC. Such methodology could be useful for other studies of ion-irradiated materials.
The step-and-shoot IMRT overshooting phenomenon: a novel method to mitigate patient overdosage.
Zhen, Heming; Ouyang, Luo; Bao, Qinan; Qin, Nan; Stojadinovic, Strahinja; Pompos, Arnold
2016-07-08
The goal of this work is to evaluate the dosimetric impact of an overshooting phenomenon in step-and-shoot IMRT delivery, and to demonstrate a novel method to mitigate the issue. Five pelvis IMRT patients treated on Varian 2100C EX linacs with larger than +4.5% phantom ion chamber point-dose difference relative to planned dose were investigated. For each patient plan, 5 fractions were delivered. DynaLog files were recorded and centi-MU pulses from dose integrator board for every control point (CP) were counted using a commercial pulse counter. The counter recorded CP MU agrees with DynaLog records, both showing an ~ 0.6MU overshoot of the first segment of every beam. The 3D patient dose was recalculated from the counter records and compared to the planned dose, showing that the overshoot resulted in on average 2.05% of PTV D95 error, and 2.49%, 2.61% and 2.45% of D1cc error for rectum, bladder, and bowel, respectively. The initial plans were then modified by inserting a specially designed MLC segment to the start of every beam. The modified plans were also delivered five times. The dose from the modified delivery was calculated using counter recorded CP MU. The corresponding Dx parameters were all within 0.31% from the original plan. IMRT QA results also show a 2.2% improvement in ion chamber point-dose agreement. The results demonstrate that the proposed plan modification method effectively eliminates the overdosage from the overshooting phenomenon. © 2016 The Authors.
Thermal diffusivity measurement by lock-in photothermal shadowgraph method
Energy Technology Data Exchange (ETDEWEB)
Cifuentes, A. [Instituto Politécnico Nacional, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Legaria, Ciudad de México 11500 (Mexico); Departamento de Física Aplicada I, Escuela Técnica Superior de Ingeniería, Universidad del País Vasco UPV/EHU, Alameda Urquijo s/n, 48013 Bilbao (Spain); Alvarado, S. [Instituto Politécnico Nacional, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Legaria, Ciudad de México 11500 (Mexico); Laboratory for Soft Matter and Biophysics, Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, Heverlee B-3001 (Belgium); Cabrera, H. [Centro Multidisciplinario de Ciencias, Instituto Venezolano de Investigaciones Científicas, IVIC, Mérida 5101, Venezuela and SPIE-ICTP Anchor Research in Optics Program Lab, International Centre for Theoretical Physics (ICTP), Strada Costiera 11, Trieste (Italy); Calderón, A.; Marín, E., E-mail: emarinm@ipn.mx [Instituto Politécnico Nacional, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Legaria, Ciudad de México 11500 (Mexico)
2016-04-28
Here, we present a novel application of the shadowgraph technique for obtaining the thermal diffusivity of an opaque solid sample, inspired by the orthogonal skimming photothermal beam deflection technique. This new variant utilizes the shadow projected by the sample when put against a collimated light source. The sample is then heated periodically by another light beam, giving rise to thermal waves, which propagate across it and through its surroundings. Changes in the refractive index of the surrounding media due to the heating distort the shadow. This phenomenon is recorded and lock-in amplified in order to determine the sample's thermal diffusivity.
a Three-Step Spatial-Temporal Clustering Method for Human Activity Pattern Analysis
Huang, W.; Li, S.; Xu, S.
2016-06-01
How people move in cities and what they do in various locations at different times form human activity patterns. Human activity pattern plays a key role in in urban planning, traffic forecasting, public health and safety, emergency response, friend recommendation, and so on. Therefore, scholars from different fields, such as social science, geography, transportation, physics and computer science, have made great efforts in modelling and analysing human activity patterns or human mobility patterns. One of the essential tasks in such studies is to find the locations or places where individuals stay to perform some kind of activities before further activity pattern analysis. In the era of Big Data, the emerging of social media along with wearable devices enables human activity data to be collected more easily and efficiently. Furthermore, the dimension of the accessible human activity data has been extended from two to three (space or space-time) to four dimensions (space, time and semantics). More specifically, not only a location and time that people stay and spend are collected, but also what people "say" for in a location at a time can be obtained. The characteristics of these datasets shed new light on the analysis of human mobility, where some of new methodologies should be accordingly developed to handle them. Traditional methods such as neural networks, statistics and clustering have been applied to study human activity patterns using geosocial media data. Among them, clustering methods have been widely used to analyse spatiotemporal patterns. However, to our best knowledge, few of clustering algorithms are specifically developed for handling the datasets that contain spatial, temporal and semantic aspects all together. In this work, we propose a three-step human activity clustering method based on space, time and semantics to fill this gap. One-year Twitter data, posted in Toronto, Canada, is used to test the clustering-based method. The results show that the
A THREE-STEP SPATIAL-TEMPORAL-SEMANTIC CLUSTERING METHOD FOR HUMAN ACTIVITY PATTERN ANALYSIS
Directory of Open Access Journals (Sweden)
W. Huang
2016-06-01
Full Text Available How people move in cities and what they do in various locations at different times form human activity patterns. Human activity pattern plays a key role in in urban planning, traffic forecasting, public health and safety, emergency response, friend recommendation, and so on. Therefore, scholars from different fields, such as social science, geography, transportation, physics and computer science, have made great efforts in modelling and analysing human activity patterns or human mobility patterns. One of the essential tasks in such studies is to find the locations or places where individuals stay to perform some kind of activities before further activity pattern analysis. In the era of Big Data, the emerging of social media along with wearable devices enables human activity data to be collected more easily and efficiently. Furthermore, the dimension of the accessible human activity data has been extended from two to three (space or space-time to four dimensions (space, time and semantics. More specifically, not only a location and time that people stay and spend are collected, but also what people “say” for in a location at a time can be obtained. The characteristics of these datasets shed new light on the analysis of human mobility, where some of new methodologies should be accordingly developed to handle them. Traditional methods such as neural networks, statistics and clustering have been applied to study human activity patterns using geosocial media data. Among them, clustering methods have been widely used to analyse spatiotemporal patterns. However, to our best knowledge, few of clustering algorithms are specifically developed for handling the datasets that contain spatial, temporal and semantic aspects all together. In this work, we propose a three-step human activity clustering method based on space, time and semantics to fill this gap. One-year Twitter data, posted in Toronto, Canada, is used to test the clustering-based method. The
Design of materials with extreme thermal expansion using a three-phase topology optimization method
DEFF Research Database (Denmark)
Sigmund, Ole; Torquato, S.
1997-01-01
Composites with extremal or unusual thermal expansion coefficients are designed using a three-phase topology optimization method. The composites are made of two different material phases and a void phase. The topology optimization method consists in finding the distribution of material phases...... materials having maximum directional thermal expansion (thermal actuators), zero isotropic thermal expansion, and negative isotropic thermal expansion. It is shown that materials with effective negative thermal expansion coefficients can be obtained by mixing two phases with positive thermal expansion...... on a finite-element discretization of the base cell. The optimization problem is solved using sequential linear programming. To benchmark the design method we first consider two-phase designs. Our optimal two-phase microstructures are in fine agreement with rigorous bounds and the so-called Vigdergauz...
Computation of point reactor dynamics equations with thermal feedback via weighted residue method
International Nuclear Information System (INIS)
Suo Changan; Liu Xiaoming
1986-01-01
Point reactor dynamics equations with six groups of delayed neutrons have been computed via weighted-residual method in which the delta function was taken as a weighting function, and the parabolic with or without exponential factor as a trial function respectively for an insertion of large or smaller reactivity. The reactivity inserted into core can be varied with time, including insertion in forms of step function, polynomials up to second power and sine function. A thermal feedback of single flow channel model was added in. The thermal equations concerned were treated by use of a backward difference technique. A WRK code has been worked out, including implementation of an automatic selection of time span based on an input of error requirement and of an automatic change between computation with large reactivity and that with smaller one. On the condition of power varied slowly and without feedback, the results are not sensitive to the selection of values of time span. At last, the comparison of relevant results has shown that the agreement is quite well
Construction of a Novel Method of Measuring Thermal Conductivity for Nanostructures
Directory of Open Access Journals (Sweden)
Hiroya Ikeda
2015-04-01
Full Text Available With the aim of characterizing the thermal conduction in a nanometer-scaled materials, we have constructed a novel method on the basis of an ac calorimetric method. In this method, periodic sample heating is performed by light irradiation and the corresponding periodic temperature is detected by infrared irradiative thermometer. This makes us measure the thermal diffusivity out of contact with the objective sample. In the present study, we confirm to measure the thermal diffusivity of bulk Si and Cu by this non-contact method with halogen-lamp irradiation. In determining the thermal diffusivity from the relationship between distance deviation and delay time, the simplest wave equation is used, and the obtained values of thermal diffusivity for Si and Cu are close to those reported. Therefore, this non-contact method is useful for evaluating the thermal conduction and applicable for nanometer-scaled materials by improving local heating and local detecting systems.
Determining Effective Thermal Conductivity of Fabrics by Using Fractal Method
Zhu, Fanglong; Li, Kejing
2010-03-01
In this article, a fractal effective thermal conductivity model for woven fabrics with multiple layers is developed. Structural models of yarn and plain woven fabric are derived based on the fractal characteristics of macro-pores (gap or channel) between the yarns and micro-pores inside the yarns. The fractal effective thermal conductivity model can be expressed as a function of the pore structure (fractal dimension) and architectural parameters of the woven fabric. Good agreement is found between the fractal model and the thermal conductivity measurements in the general porosity ranges. It is expected that the model will be helpful in the evaluation of thermal comfort for woven fabric in the whole range of porosity.
Transient thermal modelling of ball bearing using finite element method
Sibilli, Thierry; Igie, Uyioghosa
2017-01-01
Gas turbines are fitted with rolling element bearings, which transfer loads and supports the shafts. The interaction between the rotating and stationary parts in the bearing causes a conversion of some of the power into heat, influencing the thermal behaviour of the entire bearing chamber. To improve thermal modelling of bearing chambers, this work focused on modelling of the heat generated and dissipated around the bearings, in terms of magnitude and location, and the interaction with the co...
Thermal-hydraulic stability tests for newly designed BWR rod bundle (step-III fuel type A)
International Nuclear Information System (INIS)
Mitsutake, T.; Chuman, K.; Miura, S.; Morooka, S.; Moriya, K.; Kitamura, H.; Toba, A.; Omoto, A.
2004-01-01
Thermal-hydraulic stability tests have been performed on electrically heated bundles to simulate the newly designed Boiling Water Reactor (BWR) fuels in a parallel channel test loop. The objective of the current experimental program is to investigate how the newly designed bundle could improve the thermal-hydraulic stability. Measurements of the thermal-hydraulic instability thresholds in two vertical rod bundles have been conducted in steam-water two-phase flow conditions at the TOSHIBA test loop. Fluid conditions were BWR operating conditions of 7 MPa system pressure, 1.0-2.0x10 6 kg/m 2 /h inlet mass flux and 28-108 kJ/kg inlet subcooling. The parallel channel test loop consists of a main bundle of 3x3 indirectly heated rods of 1/9 symmetry of 9x9 full lattice and a bypass bundle of 8x8. These are both simulated BWR rod bundles in respect of rod diameter, heated length, rod configuration, fuel rod spacer, core inlet hydraulic resistance and upper tie plate. There are three types of the 3x3 test bundles with different configurations of a part length rod of two-thirds the length of the other rods and an axial power shape. The design innovation of the part length rod for a 9x9 lattice development, though addition of more fuel rods increases bundle pressure drop, reduces pressure drop in the two-phase portion of the bundle, and enhances the thermal hydraulic stability. Through the experiments, the parameter dependency on the channel stability threshold is obtained for inlet subcooling, inlet mass flux, inlet flow resistance, axial power shape and part length rod. The main conclusion is that the stability threshold is about 10% greater with the part length rod than without the part length rod. The new BWR bundle consisting of the part length rod has been verified in respect of thermal hydraulic stability performance. (author)
Varandani, Deepak; Agarwal, Khushboo; Brugger, Juergen; Mehta, Bodh Raj
2016-08-01
A commercial scanning thermal microscope has been upgraded to facilitate its use in estimating the radial thermal diffusivity of thin films close to room temperature. The modified setup includes a microcontroller driven microhotplate coupled with a Bluetooth module for wireless control. The microcontroller board (Arduino Leonardo) is used to generate a bias of suitable voltage amplitude and pulse duration which is applied across the microhotplate contact pads. A corresponding heat pulse from the Pt heating element (1 mm2) embedded within the microhotplate is delivered to the lower surface of the thin film (25 mm2) deposited over it. The large difference in the dimensions of the heating source and the thin film surface causes heat to flow radially outwards on the top surface of the latter. The decay of this radial heat wave as it flows outwards is recorded by the scanning thermal microscope in terms of temperature-time (T-t) profiles at varying positions around the central heating zone. A fitting procedure is suggested to extract the thermal diffusivity value from the array of T-t profiles. The efficacy of the above setup has been established by evaluating the thermal diffusivities of Bi2Te3 and Bi2Te3:Si thin film samples. Further, with only minor alterations in design the capabilities of the above setup can be extended to estimate the axial thermal diffusivity and specific heat of thin films, as a function of temperature.
Simple One-Step Method to Synthesize Polypyrrole-Indigo Carmine-Silver Nanocomposite
Loguercio, Lara Fernandes; Demingos, Pedro; Manica, Luiza de Mattos; Griep, Jordana Borges; Santos, Marcos José Leite; Ferreira, Jacqueline
2016-01-01
A nanocomposite of indigo carmine doped polypyrrole/silver nanoparticles was obtained by a one-step electrochemical process. The nanocomposite was characterized by scanning electron microscopy, infrared spectroscopy, ultraviolet-visible-near infrared spectroscopy, and cyclic voltammetry. The simple one-step process allowed the growth of silver nanoparticles during the polymerization of polypyrrole, resulting in films with electrochromic behavior and improved electroactivity. In addition, poly...
Directory of Open Access Journals (Sweden)
Y. V. Shokina
2015-01-01
Full Text Available At the Department of Food Production of Murmansk State Technical University (MSTU was developed a method of producing smoke fuel using infrared energy supply. The method provides a stable temperature pyrolysis of wood fuel is less than 400 ° C. Kinetic of the heating layer of fuel (wooden chips is affected by chip's density and moisture content. The method of calculating of the optimum modes of smoke produce, which is based on a system of differential equations of heat and mass transfer in the IR smoke generator, was previously proposed. The system of equations includes thermal characteristics (TC of the fuel layer (e.g. specific heat, thermal conductivity, thermal diffusivity. The exact definition of these characteristics affect the accuracy of the experimental calculation of optimal process conditions with use of the developed software. A definition of layer's TC by a method with elements of pulsed thermal NDT. The use of thermal imager is proposed for measuring the temperature of the irritated surface of the porous wooden chip's lawyer.
Fujiwara, Seiji; Maki, Syou; Tanaka, Seiichi; Maekawa, Ryunosuke; Masuda, Tomoki; Hagiwara, Masayuki
2017-07-01
Thermal conductivity and thermal diffusivity of hen egg-white lysozyme (HEWL) crystals were examined by using the transient short hot wire method. This method is based on the conventional hot wire method, but improved by using a wire that is much shorter than conventional ones. The magneto-Archimedes levitation technique was utilized to attach the HEWL crystals onto the wire. Owing to the upward magnetic force, the HEWL crystals were deposited at the air-liquid interface of the protein buffer solution where the short hot wire was preliminarily fixed. In situ observation clarified that the wire was completely buried into the HEWL crystals. By means of these techniques, the measurement of thermal conductivity and thermal diffusivity of HEWL crystals was realized for the first time. Gadolinium chloride (a paramagnetic subject) was used as a precipitant agent of crystallization. Crystal growth was carried out over 20 h at 17.2 °C. The applied magnetic field was 4 T. Measurements were conducted during the crystal growth at two different times. The thermal conductivity and diffusivity of the HEWL crystals were determined to be 0.410 W/(m.K) and 3.77×10-8 m2/s at 14 h after, and 0.438 W/(m.K) and 5.18×10-8 m2/s at 20 h after, respectively. We emphasize that this method is versatile and applicable for other protein crystals.
Ntombela, Berrington X. S.
2013-01-01
This paper outlines the theory of the six-step method developed by personnel in the Language and Learning department at Caledonian College of Engineering, Oman. The paper further illustrates the application of this method in teaching Project, Listening, Reading, Writing, and Speaking & Debate at Foundation level. The assumption in applying the…
Mulder, W.A.; Zhebel, E.; Minisini, S.
2013-01-01
We analyse the time-stepping stability for the 3-D acoustic wave equation, discretized on tetrahedral meshes. Two types of methods are considered: mass-lumped continuous finite elements and the symmetric interior-penalty discontinuous Galerkin method. Combining the spatial discretization with the
Mucientes, A. E.; de la Pena, M. A.
2009-01-01
The concentration-time integrals method has been used to solve kinetic equations of parallel-consecutive first-order reactions with a reversible step. This method involves the determination of the area under the curve for the concentration of a given species against time. Computer techniques are used to integrate experimental curves and the method…
Adeli, Ruhollah; Kasesaz, Yaser; Shirmardi, Seyed Pezhman; Ezaty, Arsalan
2018-03-01
For designing an appropriate neutron beam, the determination of neutron flux at any irradiation facility is an important key factor. Due to the importance of determining the thermal and epithermal neutron fluxes in a typical thermal column of a reactor, a simple and accurate technique is introduced in this study. Absolute thermal and epithermal fluxes were measured experimentally at a certain point using the foil activation method by neutron bombardment of bare and cadmium covered Au foils. The relative neutron fluxes were also derived simply by means of Monte Carlo simulation by accurate modelling of the reactor components. Finally, by normalization of the relative distribution flux with regard to information about the absolute neutron flux, the accurate thermal and epithermal neutron distributions were derived, separately. Copyright © 2017 Elsevier Ltd. All rights reserved.
Porous plasmonic nanocomposites for SERS substrates fabricated by two-step laser method
Energy Technology Data Exchange (ETDEWEB)
Koleva, M.E., E-mail: mihaela_ek@yahoo.com [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee blvd., Sofia 1784 (Bulgaria); International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044 (Japan); Nedyalkov, N.N.; Atanasov, P.A. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee blvd., Sofia 1784 (Bulgaria); Gerlach, J.W.; Hirsch, D.; Prager, A.; Rauschenbach, B. [Leibniz Institute of Surface Modification (IOM), Permoserstrasse 15, D-04318 Leipzig (Germany); Fukata, N.; Jevasuwan, W. [International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044 (Japan)
2016-04-25
This research is focused on investigation of coupled plasmonic/metal-semiconductor nanomaterials. A two-step laser-assisted method is demonstrated for formation of plasmonic Ag nanoparticles (NPs) distributed into porous metal–oxide semiconductors. The mosaic Ag-ZnO target is used for laser ablation and, subsequently, laser annealing of the deposited layer is applied. The plasmon resonance properties of the nanostructures produced are confirmed by optical transmission spectroscopy. The wurtzite structure of ZnO is formed with tilted c-axis orientation and, respectively, a mixed Raman mode appears at 580 cm{sup −1}. The oxygen pressure applied during a deposition process has impact on the morphology and thickness of the porous nanostructures, but not on the size and size distribution of AgNPs. The porous nanocomposites exhibited potential for SERS applications, most pronounced for the oxygen deficient sample, grown at lower oxygen pressure. The observed considerable SERS enhancement of R6G molecules on AgNP/ZnO can be attributed to the ZnO-to-molecule charge transfer contribution, enhanced by the additional electrons from the local surface plasmon resonance (LSPR) of AgNPs to the ZnO through the conduction band. - Highlights: • Porous AgNPs/ZnO composites are obtained by laser deposition and laser annealing. • Morphology and properties depend on growth oxygen pressure. • The emergence of mixed-symmetry Raman mode at 580 cm{sup −1} is registered. • The AgNPs/ZnO porous nanocomposites are suitable for SERS-active substrates. • The charge transfer enhanced by LSPR has a contribution to SERS effect.
Energy Technology Data Exchange (ETDEWEB)
Jaeger, W.; Sanchez, V.; Cheng, X. [Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen (Germany). Inst. for Neutron Physics and Reactor Technology; Monti, L. [Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen (Germany). Inst. for Nuclear and Energy Technologies; Hurtado, A. [Technical Univ. of Dresden (Germany). Inst. of Power Engineering
2011-07-01
At the Institute for Neutron Physics and Reactor Technology (INR) at the Karlsruhe Institute of Technology (KIT), the development and validation of coupled codes systems is one major activity. In this paper, a 2-step method is proposed to perform uncertainty and sensitivity analysis of a nuclear fuel bundle. At first, the SUSA package (Software system for Uncertainty and Sensitivity Analysis), 2 is applied to the thermal hydraulic results of the TRACE (TRACE/RELAP Advanced Computational Engine) code to identify crucial thermal hydraulic parameter combinations which are successively used in the TH/NP coupled system TRACEERANOS to account for the neutronic feedbacks. This 2-step method was applied since the TRACE-ERANOS system runs 1 input in approximately 1 day (depending on the computer configurations). Since the uncertainty and sensitivity analysis requires about 100 runs of the thermal hydraulic input (with altered parameters, running within minutes) an integral TRACE-SUSA-ERANOS analysis would need around 100 days. For this analysis a fuel assembly model of the HPLWR (High Performance Light Water Reactor) was selected. Due to the general structure of the coupling and code communication scripts, the system can be used for any kind of reactor/system which can be described with TRACE and ERANOS (e.g., fast systems) while SUSA can be applied to anything. (orig.)
Zia, Haider
2017-06-01
This paper describes an updated exponential Fourier based split-step method that can be applied to a greater class of partial differential equations than previous methods would allow. These equations arise in physics and engineering, a notable example being the generalized derivative non-linear Schrödinger equation that arises in non-linear optics with self-steepening terms. These differential equations feature terms that were previously inaccessible to model accurately with low computational resources. The new method maintains a 3rd order error even with these additional terms and models the equation in all three spatial dimensions and time. The class of non-linear differential equations that this method applies to is shown. The method is fully derived and implementation of the method in the split-step architecture is shown. This paper lays the mathematical ground work for an upcoming paper employing this method in white-light generation simulations in bulk material.
3omega method to measure thermal properties of electrically conducting small-volume liquid.
Choi, Sun Rock; Kim, Joonwon; Kim, Dongsik
2007-08-01
This work presents a method to measure the thermal conductivity and heat capacity of electrically conducting small-volume liquid samples using the 3omega technique. A mathematical model of heat transfer is derived to determine the thermal properties from the 3omega signal considering the device geometry. In order to validate the model, an experimental apparatus has been designed and set up to measure the thermal properties (thermal conductivity and heat capacity) of seven different liquid samples. The results show good agreement with other literature values, demonstrating that the suggested method is effective for measuring the thermal properties of electrically conducting liquids. More importantly, the result with a sample volume of 1 microl demonstrates the resolution of the thermal conductivity as precise as 0.01% which corresponds to a thermal-conductivity change of 10(-4) Wm K in the case of water-based solutions.
Directory of Open Access Journals (Sweden)
Hayato Tada
2015-04-01
Full Text Available Objectives: It is well known that familial hypercholesterolemia (FH is a common inherited disorder that can markedly elevate the level of plasma LDL cholesterol. However, little data exists regarding the clinical impact of the plasma triglyceride (TG-rich lipoprotein fraction, including VLDL and IDL, in FH. Thus, we assessed the hypothesis that the mutations in the LDL receptor modulate lipoprotein metabolism other than the LDL fraction. Design and methods: We investigated plasma lipoprotein with a one-step ultracentrifugation method for 146 controls (mean age=61.4±17.1 yr, mean LDL cholesterol=92.7±61.2 mg/dl, 213 heterozygous mutation-determined FH subjects (mean age=46.0±18.0 yr, mean LDL cholesterol=225.1±61.2 mg/dl, and 16 homozygous/compound heterozygous mutation-determined FH subjects (mean age=26.9±17.1 yr, mean LDL cholesterol=428.6±86.1 mg/dl. In addition, we evaluated cholesterol/TG ratio in each lipoprotein fraction separated by ultracentrifugation. Results: In addition to total cholesterol and LDL cholesterol levels, VLDL cholesterol (19.5±10.4, 25.2±19.3, 29.5±21.4 mg/dl, respectively and IDL cholesterol (8.3±3.7, 16.8±11.5, 40.0±37.3 mg/dl, respectively exhibited a tri-model distribution according to their status in LDL receptor mutation(s. Moreover, the ratios of cholesterol/TG of each lipoprotein fraction increased significantly in heterozygous FH and homozygous/compound heterozygous FH groups, compared with that of controls, suggesting that the abnormality in LDL receptor modulates the quality as well as the quantity of each lipoprotein fraction. Conclusions: Our results indicate that cholesterol in TG-rich lipoproteins, including VLDL and IDL, are significantly higher in FH subjects, revealing a tri-modal distribution according to the number of LDL receptor mutations. Keywords: LDL cholesterol, Familial hypercholesterolemia, Ultracentrifugation, Lipoprotein
Calculations of pressurized thermal shock problems with the SOLA-PTS method
International Nuclear Information System (INIS)
Daly, B.J.; Kashiwa, B.A.; Torrey, M.D.
1982-01-01
A numerical procedure has been developed for multidimensional studies of detailed fluid-thermal mixing and wall heat transfer in the cold leg and downcomer of pressurized water reactors for application to the study of pressurized thermal shock. This method is briefly described and examples of its application to various test problems are presented to demonstrate its accuracy. An application of the method to the pressurized thermal shock problem is described for the case of a main steam line break
Proposed method to improve the accuracy of thermal conductivity measurements of a planetary regolith
International Nuclear Information System (INIS)
Briggs, M.; Ambrosi, R.M.; Nelms, N.; Fraser, G.W.
2005-01-01
This paper describes a new theoretical approach for measuring thermal conductivity of a planetary regolith. The method is ideal for in situ measurement. Currently in situ measurement of thermal conductivity is widely done via the line heat source (LHS) method. The inherent problem with this method is the number and type of assumptions that are needed for the method to work. In this study we propose another method that would measure the thermal diffusivity via a spherical array method by using a temperature sensor at the core of the array. This sensor is to be used in both an active mode (to supply heat) and a passive mode (to monitor temperature). The thermal diffusivity of the material is first deduced from the temperature rise of the sensors and the heating power supplied. The thermal conductivity can then be deduced
Directory of Open Access Journals (Sweden)
Xiaowei Wang
2014-01-01
Full Text Available This paper proposes a stepped selection method based on spectral kurtosis relative energy entropy. Firstly, the length and type of window function are set; then when fault occurs, enter step 1: the polarity of first half-wave extremes is analyzed; if the ratios of extremes between neighboring lines are positive, the bus bar is the fault line, else, the SK relative energy entropies are calculated, and then enter step 2: if the obtained entropy multiple is bigger than the threshold or equal to the threshold, the overhead line of max entropy corresponding is the fault line, if not, enter step 3: the line of max entropy corresponding is the fault line. At last, the applicability of the proposed algorithm is presented, and the comparison results are discussed.
Directory of Open Access Journals (Sweden)
BEHZAD AZIZIAN ISALOO
2016-04-01
Full Text Available Maximum power point tracking (MPPT algorithms are employed in photovoltaic (PV systems to provide full utilization of PV array output power. Among all the MPPT algorithms, the Incremental Conductance (INC algorithm is widely used in PV systems due to the high tracking speed and accuracy. In this paper an improved variable step size algorithm which is based on incremental conductance algorithm is proposed that adjusts the step size according to PV output current. The result of this adaption is to make the algorithm suitable for practical operating conditions due to a wider operating range of irradiation changes. Simulation results confirm that the proposed algorithm increases convergence speed and efficiency in comparison with conventional fixed and variable step size INC algorithms.
Benhammouda, Brahim; Vazquez-Leal, Hector
2016-01-01
This work presents an analytical solution of some nonlinear delay differential equations (DDEs) with variable delays. Such DDEs are difficult to treat numerically and cannot be solved by existing general purpose codes. A new method of steps combined with the differential transform method (DTM) is proposed as a powerful tool to solve these DDEs. This method reduces the DDEs to ordinary differential equations that are then solved by the DTM. Furthermore, we show that the solutions can be improved by Laplace-Padé resummation method. Two examples are presented to show the efficiency of the proposed technique. The main advantage of this technique is that it possesses a simple procedure based on a few straight forward steps and can be combined with any analytical method, other than the DTM, like the homotopy perturbation method.
Liu, Yu; Li, Ji-Jia; Zu, Peng; Liu, Hong-Xu; Yu, Zhan-Wu; Ren, Yi
2017-12-07
To introduce a two-step method for creating a gastric tube during laparoscopic-thoracoscopic Ivor-Lewis esophagectomy and assess its clinical application. One hundred and twenty-two patients with middle or lower esophageal cancer who underwent laparoscopic-thoracoscopic Ivor-Lewis esophagectomy at Liaoning Cancer Hospital and Institute from March 2014 to March 2016 were included in this study, and divided into two groups based on the procedure used for creating a gastric tube. One group used a two-step method for creating a gastric tube, and the other group used the conventional method. The two groups were compared regarding the operating time, surgical complications, and number of stapler cartridges used. The mean operating time was significantly shorter in the two-step method group than in the conventional method group [238 (179-293) min vs 272 (189-347) min, P two groups. The two-step method for creating a gastric tube during laparoscopic-thoracoscopic Ivor-Lewis esophagectomy has the advantages of simple operation, minimal damage to the tubular stomach, and reduced use of stapler cartridges.
DEFF Research Database (Denmark)
Tordrup, Karl Woldum; Poulsen, Søren Erbs; Bjørn, Henrik
2017-01-01
Dimensioning of large-scale borehole thermal energy storage (BTES) is inherently uncertain due to the natural variability of thermal conductivity and heat capacity in the storage volume. We present an improved method for upscaling a pilot BTES to full scale and apply the method to an operational...
Engineered high expansion glass-ceramics having near linear thermal strain and methods thereof
Energy Technology Data Exchange (ETDEWEB)
Dai, Steve Xunhu; Rodriguez, Mark A.; Lyon, Nathanael L.
2018-01-30
The present invention relates to glass-ceramic compositions, as well as methods for forming such composition. In particular, the compositions include various polymorphs of silica that provide beneficial thermal expansion characteristics (e.g., a near linear thermal strain). Also described are methods of forming such compositions, as well as connectors including hermetic seals containing such compositions.
Method of operating a thermal engine powered by a chemical reaction
Ross, John; Escher, Claus
1988-01-01
The invention involves a novel method of increasing the efficiency of a thermal engine. Heat is generated by a non-linear chemical reaction of reactants, said heat being transferred to a thermal engine such as Rankine cycle power plant. The novel method includes externally perturbing one or more of the thermodynamic variables of said non-linear chemical reaction.
Simple One-Step Method to Synthesize Polypyrrole-Indigo Carmine-Silver Nanocomposite
Directory of Open Access Journals (Sweden)
Lara Fernandes Loguercio
2016-01-01
Full Text Available A nanocomposite of indigo carmine doped polypyrrole/silver nanoparticles was obtained by a one-step electrochemical process. The nanocomposite was characterized by scanning electron microscopy, infrared spectroscopy, ultraviolet-visible-near infrared spectroscopy, and cyclic voltammetry. The simple one-step process allowed the growth of silver nanoparticles during the polymerization of polypyrrole, resulting in films with electrochromic behavior and improved electroactivity. In addition, polypyrrole chains in the nanocomposite were found to present longer conjugation length than pristine polypyrrole films.
Modified Pressure-Correction Projection Methods: Open Boundary and Variable Time Stepping
Bonito, Andrea
2014-10-31
© Springer International Publishing Switzerland 2015. In this paper, we design and study two modifications of the first order standard pressure increment projection scheme for the Stokes system. The first scheme improves the existing schemes in the case of open boundary condition by modifying the pressure increment boundary condition, thereby minimizing the pressure boundary layer and recovering the optimal first order decay. The second scheme allows for variable time stepping. It turns out that the straightforward modification to variable time stepping leads to unstable schemes. The proposed scheme is not only stable but also exhibits the optimal first order decay. Numerical computations illustrating the theoretical estimates are provided for both new schemes.
A method of measuring the thermal conductivity of liquids
Held, E.F.M. van der; Drunen, F.G. van
1949-01-01
We described the development of an apparatus for the determination of the thermal conductivity of liquids. The apparatus is suitable for all kinds of liquids, including the strongest acids. From a given time we pass an electric current through a thin straight wire, placed in a homogeneous material
Solid Waste Decontamination by Thermal Desorption and Catalytic Oxidation Methods
Czech Academy of Sciences Publication Activity Database
Šolcová, Olga; Topka, Pavel; Soukup, Karel; Jirátová, Květa; Váňová, H.; Kaštánek, František
2014-01-01
Roč. 68, č. 9 (2014), s. 1279-1282 ISSN 0366-6352 R&D Projects: GA MPO FR-TI1/059 Institutional support: RVO:67985858 Keywords : thermal desorption * catalytic oxidation * soil decontamination Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.468, year: 2014
THERMAL FISSION REACTOR COMPOSITIONS AND METHOD OF FABRICATING SAME
Blainey, A.
1959-10-01
A body is presented for use in a thermal fission reactor comprising a sintered compressed mass of a substance of the group consisting of uranium, thorium, and oxides and carbides of uranium and thorium, enclosed in an envelope of a sintered, compacted, heat-conductive material of the group consisting of beryllium, zirconium, and oxides and carbides of beryllium and zirconium.
Interconnected hydro-thermal systems - Models, methods, and applications
DEFF Research Database (Denmark)
Hindsberger, Magnus
2003-01-01
in the Baltic Sea Region. They are characterised by having a mix of hydroelectric and thermal based production units, where the latter type includes the combined heat and power (CHP) plants that are widely used in e.g. Denmark and Finland. Focus is on the medium- to long-term perspective, i.e. within a time...
A method for storing energy in the thermal form
International Nuclear Information System (INIS)
Bonnin, Jacques.
1973-01-01
The thermal energy generated during slack hours by a main energy-generating unit A is partially used for heating a storage fluid flowing in a storage and recovery unit B, and that storage fluid which is preferably water, is stored under pressure in a tank. This can be applied to light water nuclear power stations [fr
A two-step method for variable selection in the analysis of a case-cohort study.
Newcombe, P J; Connolly, S; Seaman, S; Richardson, S; Sharp, S J
2017-11-10
Accurate detection and estimation of true exposure-outcome associations is important in aetiological analysis; when there are multiple potential exposure variables of interest, methods for detecting the subset of variables most likely to have true associations with the outcome of interest are required. Case-cohort studies often collect data on a large number of variables which have not been measured in the entire cohort (e.g. panels of biomarkers). There is a lack of guidance on methods for variable selection in case-cohort studies. We describe and explore the application of three variable selection methods to data from a case-cohort study. These are: (i) selecting variables based on their level of significance in univariable (i.e. one-at-a-time) Prentice-weighted Cox regression models; (ii) stepwise selection applied to Prentice-weighted Cox regression; and (iii) a two-step method which applies a Bayesian variable selection algorithm to obtain posterior probabilities of selection for each variable using multivariable logistic regression followed by effect estimation using Prentice-weighted Cox regression. Across nine different simulation scenarios, the two-step method demonstrated higher sensitivity and lower false discovery rate than the one-at-a-time and stepwise methods. In an application of the methods to data from the EPIC-InterAct case-cohort study, the two-step method identified an additional two fatty acids as being associated with incident type 2 diabetes, compared with the one-at-a-time and stepwise methods. The two-step method enables more powerful and accurate detection of exposure-outcome associations in case-cohort studies. An R package is available to enable researchers to apply this method. © The Author 2017. Published by Oxford University Press on behalf of the International Epidemiological Association.
Energy Technology Data Exchange (ETDEWEB)
Ghomshei, Mansour Mohieddin; Abbasi, Vahid [Islamic Azad University, Alborz (Iran, Islamic Republic of)
2013-04-15
In this paper, a finite element formulation is developed for analyzing the axisymmetric thermal buckling of FGM annular plates of variable thickness subjected to thermal loads generally distributed nonuniformly along the plate radial coordinate. The FGM assumed to be isotropic with material properties graded in the thickness direction according to a simple power-law in terms of the plate thickness coordinate, and has symmetry with respect to the plate midplane. At first, the pre-buckling plane elasticity problem is developed and solved using the finite element method, to determine the distribution of the pre-buckling in-plane forces in terms of the temperature rise distribution. Subsequently, based on Kierchhoff plate theory and using the principle of minimum total potential energy, the weak form of the differential equation governing the plate thermal stability is derived, then by employing the finite element method, the stability equations are solved numerically to evaluate the thermal buckling load factor. Convergence and validation of the presented finite element model are investigated by comparing the numerical results with those available in the literature. Parametric studies are carried out to cover the effects of parameters including thickness-to-radius ratio, taper parameter and boundary conditions on the thermal buckling load factor of the plates.
Photon strength function in the Hf-181 nucleus by method of two-step cascade
Le Hong Khiem
2003-01-01
The applicability of sum-coincidence measurements of two-step cascade gamma ray spectra determining Photon Strength Function (PSF) of Hf-181 induced from Hf-180 (n,2 gamma) Hf-181 reaction is presented. Up to 80% intensity of the primary gamma ray transitions in a wide energy range have been deduced and compared to model calculation.
The Mixing of Methods: a three-step process for improving rigour in impact evaluations
Ton, G.
2012-01-01
This article describes a systematic process that is helpful in improving impact evaluation assignments, within restricted budgets and timelines. It involves three steps: a rethink of the key questions of the evaluation to develop more relevant, specific questions; a way of designing a mix of
Variable order one-step methods for initial value problems I ...
African Journals Online (AJOL)
A class of variable order one-step integrators is proposed for Initial Value Problems (IVPs) in Ordinary Differential Equations (ODEs). It is based on a rational interpolant. Journal of the Nigerian Association of Mathematical Physics Vol. 10 2006: pp. 91-96 ...
Keslerová, R.; Kozel, K.
2014-03-01
This work deals with the numerical solution of viscous and viscoelastic fluids flow. The governing system of equations is based on the system of balance laws for mass and momentum for incompressible laminar fluids. Different models for the stress tensor are considered. For viscous fluids flow Newtonian model is used. For the describing of the behaviour of the mixture of viscous and viscoelastic fluids Oldroyd-B model is used. Numerical solution of the described models is based on cell-centered finite volume method in conjunction with artificial compressibility method. For time integration an explicit multistage Runge-Kutta scheme is used. In the case of unsteady computation dual-time stepping method is considered. The principle of dual-time stepping method is following. The artificial time is introduced and the artificial compressibility method in the artificial time is applied.
Directory of Open Access Journals (Sweden)
L. Wang
2014-06-01
Full Text Available The first prerequisite for fabricating the thermal barrier coatings (TBCs with excellent performance is to find an optimized coating structure with high thermal insulation effect and low residual stress. This paper discusses the design and optimization of a suitable coating structure for the TBCs prepared by atmospheric plasma spraying (APS using the finite element method. The design and optimization processes comply with the rules step by step, as the structure develops from a simple to a complex one. The research results indicate that the suitable thicknesses of the bond-coating and top-coating are 60–120 μm and 300–420 μm, respectively, for the single ceramic layer YSZ/NiCoCrAlY APS-TBC. The embedded interlayer (50 wt.%YSZ + 50 wt.%NiCoCrAlY will further reduce the residual stress without sacrificing the thermal insulation effect. The double ceramic layer was further considered which was based on the single ceramic layer TBC. The embedded interlayer and the upper additional ceramic layer will have a best match between the low residual stress and high thermal insulation effect. Finally, the optimized coating structure was obtained, i.e., the La2Ce2O7(LC/YSZ/Interlayer/NiCoCrAlY coating structure with appropriate layer thickness is the best choice. The effective thermal conductivity of this optimized LC/YSZ/IL/BL TBC is 13.2% lower than that of the typical single ceramic layer YSZ/BL TBC.
International Nuclear Information System (INIS)
Meyer, Chad D.; Balsara, Dinshaw S.; Aslam, Tariq D.
2014-01-01
Parabolic partial differential equations appear in several physical problems, including problems that have a dominant hyperbolic part coupled to a sub-dominant parabolic component. Explicit methods for their solution are easy to implement but have very restrictive time step constraints. Implicit solution methods can be unconditionally stable but have the disadvantage of being computationally costly or difficult to implement. Super-time-stepping methods for treating parabolic terms in mixed type partial differential equations occupy an intermediate position. In such methods each superstep takes “s” explicit Runge–Kutta-like time-steps to advance the parabolic terms by a time-step that is s 2 times larger than a single explicit time-step. The expanded stability is usually obtained by mapping the short recursion relation of the explicit Runge–Kutta scheme to the recursion relation of some well-known, stable polynomial. Prior work has built temporally first- and second-order accurate super-time-stepping methods around the recursion relation associated with Chebyshev polynomials. Since their stability is based on the boundedness of the Chebyshev polynomials, these methods have been called RKC1 and RKC2. In this work we build temporally first- and second-order accurate super-time-stepping methods around the recursion relation associated with Legendre polynomials. We call these methods RKL1 and RKL2. The RKL1 method is first-order accurate in time; the RKL2 method is second-order accurate in time. We verify that the newly-designed RKL1 and RKL2 schemes have a very desirable monotonicity preserving property for one-dimensional problems – a solution that is monotone at the beginning of a time step retains that property at the end of that time step. It is shown that RKL1 and RKL2 methods are stable for all values of the diffusion coefficient up to the maximum value. We call this a convex monotonicity preserving property and show by examples that it is very useful
Zauzolkova, Natalya; Dobrokhotova, Zhanna; Lermontov, Anatoly; Zorina, Ekaterina; Emelina, Anna; Bukov, Mikhail; Chernyshev, Vladimir; Sidorov, Aleksey; Kiskin, Mikhail; Bogomyakov, Artem; Lytvynenko, Anton; Kolotilov, Sergey; Velikodnyi, Yuriy; Kovba, Maksim; Novotortsev, Vladimir; Eremenko, Igor
2013-01-01
The reactions of CuSO4·5H2O, dimethylmalonic acid and Ba(OH)2·H2O (Cu: H2Me2mal: Ba=1: 2: 2) in aqueous and aqueous-ethanol solutions (H2O: EtOH=1: 1) resulted in formation of 3D-porous coordination polymers [(H2O)3(μ-H2O)2CuBa(μ3-Me2mal)(Me2mal)]n (1) and [(μ-H2O)CuBa(μ3-Me2mal)(μ4-Me2mal)]n (2), respectively. It has been shown that compound 2 was an intermediate in the thermal degradation of compound 1. Thorough studies of solid-state thermolysis of 1 and 2 allowed to detect formation of coordination polymer [CuBa(μ4-Me2mal)(μ5-Me2mal)]n (3), structure of which was determined by X-ray powder diffraction. It has been found that the channels in polymer 3 were accessible for guest molecules (MeOH). Theoretical estimation of methanol diffusion barrier was carried out. Complete solid-phase thermolysis of 1 and 2 leads to a mixture of BaCuO2, BaCO3, and CuO. Special conditions for obtaining of a crystalline phase of pure cubic BaCuO2 were determined.
Systems and methods for thermal imaging technique for measuring mixing of fluids
Booten, Charles; Tomerlin, Jeff; Winkler, Jon
2016-06-14
Systems and methods for thermal imaging for measuring mixing of fluids are provided. In one embodiment, a method for measuring mixing of gaseous fluids using thermal imaging comprises: positioning a thermal test medium parallel to a direction gaseous fluid flow from an outlet vent of a momentum source, wherein when the source is operating, the fluid flows across a surface of the medium; obtaining an ambient temperature value from a baseline thermal image of the surface; obtaining at least one operational thermal image of the surface when the fluid is flowing from the outlet vent across the surface, wherein the fluid has a temperature different than the ambient temperature; and calculating at least one temperature-difference fraction associated with at least a first position on the surface based on a difference between temperature measurements obtained from the at least one operational thermal image and the ambient temperature value.
Ipek, Hava; Calik, Muammer
2008-01-01
Based on students' alternative conceptions of the topics "electric circuits", "electric charge flows within an electric circuit", "how the brightness of bulbs and the resistance changes in series and parallel circuits", the current study aims to present a combination of different conceptual change methods within a four-step constructivist teaching…
Simplified method for yearlong thermal analysis of building prototypes
Energy Technology Data Exchange (ETDEWEB)
Krueger, E.L.; Laroca, C. [Departamento de Construcao Civil, Universidade Tecnologica Federal do Parana, Av. Sete de Setembro, 3165, CEP, 80230-901 Curitiba, PR (Brazil); Givoni, B. [Department of Architecture, School of Arts and Architecture, UCLA, Los Angeles, CA (United States); Ben Gurion University (Israel)
2011-02-15
The paper presents the thermal analysis of a low-cost prototype consisting of plywood panels, which was designed and built by one of the authors within the scope of a program for subsidized low-cost housing. The object of analysis is a building prototype located in Canoinhas, in the South of Brazil (26 10'38''S, altitude 765 m above sea level). The present paper is concerned with evaluating the thermal performance of the prototype over given periods of the year by means of onsite measurements and indoor temperature predictions for the various rooms of the building prototype. From obtained results, the overall performance of the building as well as the individual performance of each room was evaluated. (author)
Method and apparatus for thermal management of vehicle exhaust systems
Benson, D.K.; Potter, T.F.
1995-12-26
A catalytic converter is surrounded by variable conductance insulation for maintaining the operating temperature of the catalytic converter at an optimum level, for inhibiting heat loss when raising catalytic converter temperature to light-off temperature, for storing excess heat to maintain or accelerate reaching light-off temperature, and for conducting excess heat away from the catalytic converter after reaching light-off temperature. The variable conductance insulation includes vacuum gas control and metal-to-metal thermal shunt mechanisms. Radial and axial shielding inhibits radiation and convection heat loss. Thermal storage media includes phase change material, and heat exchanger chambers and fluids carry heat to and from the catalytic converter. 7 figs.
Method of systematic determination of specific thermal characteristics of building
Directory of Open Access Journals (Sweden)
Prokhorov Vitaliy
2016-01-01
Full Text Available In the paper the classical term «specific thermal characteristics of building» proposed by professor Chaplin V.M. for heating systems developing also for others heat-consuming system for building such as ventilation, air conditioning, hot-water supply system is observed. The followings attributing values are established: external building volume, temperature potential in annual crevice cycle.
Thermal imaging method to visualize a hidden painting thermally excited by far infrared radiations
Davin, T.; Wang, X.; Chabane, A.; Pawelko, R.; Guida, G.; Serio, B.; Hervé, P.
2015-06-01
The diagnosis of hidden painting is a major issue for cultural heritage. In this paper, a non-destructive active infrared thermographic technique was considered to reveal paintings covered by a lime layer. An extended infrared spectral range radiation was used as the excitation source. The external long wave infrared energy source delivered to the surface is then propagated through the material until it encounters a painting zone. Due to several thermal effects, the sample surface then presents non-uniformity patterns. Using a high sensitive infrared camera, the presence of covered pigments can thus be highlighted by the analysis of the non-stationary phenomena. Reconstituted thermal contrast images of mural samples covered by a lime layer are shown.
Thermal control system and method for a passive solar storage wall
Ortega, Joseph K. E.
1984-01-01
The invention provides a system and method for controlling the storing and elease of thermal energy from a thermal storage wall wherein said wall is capable of storing thermal energy from insolation of solar radiation. The system and method includes a device such as a plurality of louvers spaced a predetermined distance from the thermal wall for regulating the release of thermal energy from the thermal wall. This regulating device is made from a material which is substantially transparent to the incoming solar radiation so that when it is in any operative position, the thermal storage wall substantially receives all of the impacting solar radiation. The material in the regulating device is further capable of being substantially opaque to thermal energy so that when the device is substantially closed, thermal release of energy from the storage wall is substantially minimized. An adjustment device is interconnected with the regulating mechanism for selectively opening and closing it in order to regulate the release of thermal energy from the wall.
Directory of Open Access Journals (Sweden)
Ioannis K. Argyros
2017-12-01
Full Text Available This paper is devoted to the study of a multi-step method with divided differences for solving nonlinear equations in Banach spaces. In earlier studies, hypotheses on the Fréchet derivative up to the sixth order of the operator under consideration is used to prove the convergence of the method. That restricts the applicability of the method. In this paper we extended the applicability of the sixth-order multi-step method by using only hypotheses on the first derivative of the operator involved. Our convergence conditions are weaker than the conditions used in earlier studies. Numerical examples where earlier results cannot be applied to solve equations but our results can be applied are also given in this study.
some generalized two-step block hybrid numerov method for solving ...
African Journals Online (AJOL)
Nwokem et al.
Equations, Continuous formulation, Interpolation and Collocation,. Numerov method. INTRODUCTION ... continuous linear multistep methods (CLMS) of hybrid type via multistep collocation technique. This method helps to ...... continuous integration for ordinary differential equations,. Journal of Nigeria Mathematical Society: ...
DEFF Research Database (Denmark)
Karlsen, Brian; Larsen, Jan; Jakobsen, Kaj Bjarne
2000-01-01
The result from field-tests using a Stepped-Frequency Ground Penetrating Radar (SF-GPR) and promising antenna and air-ground deembedding methods for a SF-GPR is presented. A monostatic S-band rectangular waveguide antenna was used in the field-tests. The advantages of the SF-GPR, e.g., amplitude....... The methods are successfully evaluated on field-test data obtained from measurements on a large-scale in-door test field....
Jajesniak, Pawel; Wong, Tuck Seng
2015-01-01
Molecular cloning is an essential step in biological engineering. Methods involving megaprimer-based PCR of a whole plasmid are promising alternatives to the traditional restriction-ligation-based molecular cloning. Their widespread use, however, is hampered by some of their inherent characteristics, e.g., linear amplification, use of self-annealing megaprimers and difficulty with performing point insertion of DNA. These limitations result in low product yield and reduced flexibility in the design of a genetic construct. Here, we present a novel technique of directional cloning, which overcomes these problems yet retaining the simplicity of whole-plasmid amplification. QuickStep-Cloning utilizes asymmetric PCRs to create a megaprimer pair with 3'-overhangs, and hence, facilitates the subsequent exponential whole-plasmid amplification. QuickStep-Cloning generates nicked-circular plasmids, thereby permitting direct bacterial transformation without DNA ligation. It allows DNA fragment integration into any plasmid at any position, in an efficient, time- and cost-effective manner, without tedious intermediate DNA gel purification, modified oligonucleotides, specialty enzymes and ultra-competent cells. The method is compatible with competent E. coli cells prepared using the conventional calcium chloride method. QuickStep-Cloning expands the versatility of megaprimer-based cloning. It is an excellent addition to the cloning toolbox, for the benefit of protein engineers, metabolic engineers and synthetic biologists.
Ahmad, Arine Fadzlun; Lonnen, James; Andrew, Peter W; Kilvington, Simon
2011-10-15
Naegleria fowleri is a small free-living amoebo-flagellate found in natural and manmade thermal aquatic habitats worldwide. The organism is pathogenic to man causing fatal primary amoebic meningoencephalitis (PAM). Infection typically results from bathing in contaminated water and is usually fatal. It is, therefore, important to identify sites containing N. fowleri in the interests of preventive public health microbiology. Culture of environmental material is the conventional method for the isolation of N. fowleri but requires several days incubation and subsequent biochemical or molecular tests to confirm identification. Here, a nested one-step PCR test, in conjunction with a direct DNA extraction from water or sediment material, was developed for the rapid and reliable detection of N. fowleri from the environment. Here, the assay detected N, fowleri in 18/109 river water samples associated with a nuclear power plant in South West France and 0/10 from a similar site in the UK. Although culture of samples yielded numerous thermophilic free-living amoebae, none were N. fowleri or other thermophilic Naegleria spp. The availability of a rapid, reliable and sensitive one-step nested PCR method for the direct detection of N. fowleri from the environment may aid ecological studies and enable intervention to prevent PAM cases. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.
A New Method to Determine Thermal Properties of the Mixture of PCM and Concrete
DEFF Research Database (Denmark)
R., Cheng; Pomianowski, Michal Zbigniew; Heiselberg, Per
Integration of phase change materials in building envelopes is a technology that with high potential to decrease the building energy consumption and improve indoor thermal comfort. Accurate measurement of thermal physical properties of PCM-concretes is very important for simulation and evaluation...... of its energy saving performance. However, there isn’t an effective way to measure thermal physical properties of PCM-concretes accurately. The shortcomings of using traditional testing methods to measure thermal physical properties of PCM-concretes were firstly analyzed. Then a new method based...... on the inverse problem was proposed to deal with the measurements of thermal conductivity and specific heat of PCM-concretes during the phase change process. This method transforms the determination process to an optimization problem, which regarded the difference between the measured and calculated heat flux...
Robert Setekera; Luuk Tiemeijer; Ramses van der Toorn
2014-01-01
In this paper an extensive verification of the extraction method (published earlier) that consistently accounts for self-heating and Early effect to accurately extract both base and thermal resistance of bipolar junction transistors is presented. The method verification is demonstrated on advanced RF SiGe HBTs were the extracted results for the thermal resistance are compared with those from another published method that ignores the effect of Early effect on internal base...
Ghaderi, Forouzan; Ghaderi, Amir H; Ghaderi, Noushin; Najafi, Bijan
2017-01-01
Background: The thermal conductivity of fluids can be calculated by several computational methods. However, these methods are reliable only at the confined levels of density, and there is no specific computational method for calculating thermal conductivity in the wide ranges of density. Methods: In this paper, two methods, an Artificial Neural Network (ANN) approach and a computational method established upon the Rainwater-Friend theory, were used to predict the value of thermal conductivity in all ranges of density. The thermal conductivity of six refrigerants, R12, R14, R32, R115, R143, and R152 was predicted by these methods and the effectiveness of models was specified and compared. Results: The results show that the computational method is a usable method for predicting thermal conductivity at low levels of density. However, the efficiency of this model is considerably reduced in the mid-range of density. It means that this model cannot be used at density levels which are higher than 6. On the other hand, the ANN approach is a reliable method for thermal conductivity prediction in all ranges of density. The best accuracy of ANN is achieved when the number of units is increased in the hidden layer. Conclusion: The results of the computational method indicate that the regular dependence between thermal conductivity and density at higher densities is eliminated. It can develop a nonlinear problem. Therefore, analytical approaches are not able to predict thermal conductivity in wide ranges of density. Instead, a nonlinear approach such as, ANN is a valuable method for this purpose.
Method for thermal processing alumina-enriched spinel single crystals
Jantzen, Carol M.
1995-01-01
A process for age-hardening alumina-rich magnesium aluminum spinel to obtain the desired combination of characteristics of hardness, clarity, flexural strength and toughness comprises selection of the time-temperature pair for isothermal heating followed by quenching. The time-temperature pair is selected from the region wherein the precipitate groups have the characteristics sought. The single crystal spinel is isothermally heated and will, if heated long enough pass from its single phase through two pre-precipitates and two metastable precipitates to a stable secondary phase precipitate within the spinel matrix. Quenching is done slowly at first to avoid thermal shock, then rapidly.
Advanced Computational Methods for Thermal Radiative Heat Transfer
Energy Technology Data Exchange (ETDEWEB)
Tencer, John; Carlberg, Kevin Thomas; Larsen, Marvin E.; Hogan, Roy E.,
2016-10-01
Participating media radiation (PMR) in weapon safety calculations for abnormal thermal environments are too costly to do routinely. This cost may be s ubstantially reduced by applying reduced order modeling (ROM) techniques. The application of ROM to PMR is a new and unique approach for this class of problems. This approach was investigated by the authors and shown to provide significant reductions in the computational expense associated with typical PMR simulations. Once this technology is migrated into production heat transfer analysis codes this capability will enable the routine use of PMR heat transfer in higher - fidelity simulations of weapon resp onse in fire environments.
Niittynen, J.; Abbel, R.; Mäntysalo, M.; Perelaer, J.; Schubert, U.S.; Lupo, D.
2014-01-01
In this contribution several alternative sintering methods are compared to traditional thermal sintering as high temperature and long process time of thermal sintering are increasing the costs of inkjet-printing and preventing the use of this technology in large scale manufacturing. Alternative
Mixed time integration methods for transient thermal analysis of structures, appendix 5
Liu, W. K.
1982-01-01
Mixed time integration methods for transient thermal analysis of structures are studied. An efficient solution procedure for predicting the thermal behavior of aerospace vehicle structures was developed. A 2D finite element computer program incorporating these methodologies is being implemented. The performance of these mixed time finite element algorithms can then be evaluated employing the proposed example problem.
Szafner, G.; Bicanic, D.D.; Kulcsár, R.; Doka, O.
2014-01-01
Thermophysical properties of foods are of considerable relevance to food industry. The One among less explored thermophysical quantities is the thermal effusivity. In this paper the front variant of the photopyroelectric method was applied to determine thermal effusivity of both, fresh hen egg¿s
A heat accumulation method and a direct-contact, latent melting-heat thermal accumulator
International Nuclear Information System (INIS)
Bricard, Alain; Moracchioli, Robert; Goffinet, Pierre; Kurka, Gerard; Cachard, Maurice de.
1974-01-01
The present invention relates to a thermal accumulation method and to a direct-contact, latent melting-heat thermal accumulator. According to the invention, a fluid is caused to flow in direct contact with a material for storing heat, said material being in divided form. This can be applied to the storage of energy [fr
Stress induced growth of Sn nanowires in a single step by sputtering method
Yadav, A.; Patel, N.; Miotello, A.; Kothari, D. C.
2015-06-01
Sn nanowires in aluminum film have been synthesized in a single step by co-sputtering of Al and Sn targets. Due to immiscibility of Sn and Al, co-sputtering leads to generation of stress in the composite film. In order to attain thermodynamic equilibrium, Sn separates from Al and diffuses towards the grain boundaries. External perturbation due to ambient atmosphere leads to corrosion at the grain boundaries forming pits which provide path for Sn to evolve. Owing to this, extrusion of Sn nanowires from Al film occurs to release the residual stress in the film.
Gibbons, William T; Venstrom, Luke J; De Smith, Robert M; Davidson, Jane H; Jackson, Gregory S
2014-07-21
Zirconium-doped ceria (Ce(1-x)Zr(x)O2) was synthesized through a controlled electrospinning process as a promising approach to cost-effective, sinter-resistant material structures for high-temperature, solar-driven thermochemical redox cycles. To approximate a two-step redox cycle for solar fuel production, fibrous Ce(1-x)Zr(x)O2 with relatively low levels of Zr-doping (0 production. Cycle stability of the fibrous Ce(1-x)Zr(x)O2 (with x = 0.025) was assessed for a range of conditions by measuring rates of O2 release during reduction and CO production during reoxidation and by assessing post-cycling fiber crystallite sizes and surface areas. Sintering increases with reduction temperature but occurs primarily along the fiber axes. Even after 108 redox cycles with reduction at 1400 °C and oxidation with CO2 at 800 °C, the fibers maintain their structure with surface areas of ∼0.3 m(2) g(-1), higher than those observed in the literature for other ceria-based structures operating at similarly high temperature conditions. Total CO production and peak production rate stabilize above 3.0 mL g(-1) and 13.0 mL min(-1) g(-1), respectively. The results show the potential for electrospun oxides as sinter-resistant material structures with adequate surface area to support rapid CO2 splitting in solar thermochemical redox cycles.
Directory of Open Access Journals (Sweden)
Yuting Tang
2016-11-01
Full Text Available Microalgae are a valuable source of lipid feedstocks for biodiesel and valuable omega-3 fatty acids. Nannochloropsis gaditana has emerged as a promising producer of eicosapentaenoic acid (EPA due to its fast growth rate and high EPA content. In the present study, the fatty acid profile of Nannochloropsis gaditana was found to be naturally high in EPA and devoid of docosahexaenoic acid (DHA, thereby providing an opportunity to maximize the efficacy of EPA production. Using an optimized one-step in situ transesterification method (methanol:biomass = 90 mL/g; HCl 5% by vol.; 70 °C; 1.5 h, the maximum fatty acid methyl ester (FAME yield of Nannochloropsis gaditana cultivated under rich condition was quantified as 10.04% ± 0.08% by weight with EPA-yields as high as 4.02% ± 0.17% based on dry biomass. The total FAME and EPA yields were 1.58- and 1.23-fold higher separately than that obtained using conventional two-step method (solvent system: methanol and chloroform. This one-step in situ method provides a fast and simple method to measure fatty acid methyl ester (FAME yields and could serve as a promising method to generate eicosapentaenoic acid methyl ester from microalgae.
Mendez, Andreas Sebastian Loureiro; Mantovani, Luciano; Barbosa, Fábio de Souza; Sayago, Carla T.M.; Garcia, Cassia Virginia; Paula, Fávero Reisdorfer; Silva, Fabiana Ernestina Barcellos da; Denardin, Elton Luis Gasparotto; Schapoval, Elfrides Eva Scherman
2011-01-01
Doripenem was characterized through physicochemical and spectroscopic techniques, as well as thermal analysis. TLC (Rf = 0.62) and HPLC (rt = 7.4 min) were found to be adequate to identify the drug. UV and infrared spectra showed similar profile between doripenem bulk and standard. The 1H and 13C NMR analysis revealed chemical shifts that allowed identifying the drug. Thermal analysis demonstrated three steps with mass loss, at 128, 178 and 276 oC. The work was successfully applied to qualita...
A non-destructive method to measure the thermal properties of frozen soils during phase transition
Directory of Open Access Journals (Sweden)
Bin Zhang
2015-04-01
Full Text Available Frozen soils cover about 40% of the land surface on the earth and are responsible for the global energy balances affecting the climate. Measurement of the thermal properties of frozen soils during phase transition is important for analyzing the thermal transport process. Due to the involvement of phase transition, the thermal properties of frozen soils are rather complex. This paper introduces the uses of a multifunctional instrument that integrates time domain reflectometry (TDR sensor and thermal pulse technology (TPT to measure the thermal properties of soil during phase transition. With this method, the extent of phase transition (freezing/thawing was measured with the TDR module; and the corresponding thermal properties were measured with the TPT module. Therefore, the variation of thermal properties with the extent of freezing/thawing can be obtained. Wet soils were used to demonstrate the performance of this measurement method. The performance of individual modules was first validated with designed experiments. The new sensor was then used to monitor the properties of soils during freezing–thawing process, from which the freezing/thawing degree and thermal properties were simultaneously measured. The results are consistent with documented trends of thermal properties variations.
Kaisheng Zhang; Pan Cheng; Lifeng He
2014-01-01
According to the characteristics of photovoltaic cell output power curve, this paper analyzed and explained the principle of Maximum Power Point Tracking (MPPT) and both advantages and disadvantages of constant voltage tracking method & perturbation observation method. Further, in combination with the advantages of existing maximum power tracking methods, this paper comes up with an improved tracking method which is recognized as maximum power point tracking combined with constant voltage tra...
A Four-Step Block Hybrid Adams-Moulton Methods For The Solution ...
African Journals Online (AJOL)
This paper examines application of the Adam-Moulton's Method and proposes a modified self-starting continuous formula Called hybrid Adams-Moulton methods for the case k=4. It allows evaluation at both grid and off grid points to obtain the discrete schemes used in the block methods. The order, error constant and ...
On some properties of the block linear multi-step methods | Chollom ...
African Journals Online (AJOL)
The convergence, stability and order of Block linear Multistep methods have been determined in the past based on individual members of the block. In this paper, methods are proposed to examine the properties of the entire block. Some Block Linear Multistep methods have been considered, their convergence, stability and ...
Estimation of oil reservoir thermal properties through temperature log data using inversion method
International Nuclear Information System (INIS)
Cheng, Wen-Long; Nian, Yong-Le; Li, Tong-Tong; Wang, Chang-Long
2013-01-01
Oil reservoir thermal properties not only play an important role in steam injection well heat transfer, but also are the basic parameters for evaluating the oil saturation in reservoir. In this study, for estimating reservoir thermal properties, a novel heat and mass transfer model of steam injection well was established at first, this model made full analysis on the wellbore-reservoir heat and mass transfer as well as the wellbore-formation, and the simulated results by the model were quite consistent with the log data. Then this study presented an effective inversion method for estimating the reservoir thermal properties through temperature log data. This method is based on the heat transfer model in steam injection wells, and can be used to predict the thermal properties as a stochastic approximation method. The inversion method was applied to estimate the reservoir thermal properties of two steam injection wells, it was found that the relative error of thermal conductivity for the two wells were 2.9% and 6.5%, and the relative error of volumetric specific heat capacity were 6.7% and 7.0%,which demonstrated the feasibility of the proposed method for estimating the reservoir thermal properties. - Highlights: • An effective inversion method for predicting the oil reservoir thermal properties was presented. • A novel model for steam injection well made full study on the wellbore-reservoir heat and mass transfer. • The wellbore temperature field and steam parameters can be simulated by the model efficiently. • Both reservoirs and formation thermal properties could be estimated simultaneously by the proposed method. • The estimated steam temperature was quite consistent with the field data
Panczak, Tim; Ring, Steve; Welch, Mark
1999-01-01
Thermal engineering has long been left out of the concurrent engineering environment dominated by CAD (computer aided design) and FEM (finite element method) software. Current tools attempt to force the thermal design process into an environment primarily created to support structural analysis, which results in inappropriate thermal models. As a result, many thermal engineers either build models "by hand" or use geometric user interfaces that are separate from and have little useful connection, if any, to CAD and FEM systems. This paper describes the development of a new thermal design environment called the Thermal Desktop. This system, while fully integrated into a neutral, low cost CAD system, and which utilizes both FEM and FD methods, does not compromise the needs of the thermal engineer. Rather, the features needed for concurrent thermal analysis are specifically addressed by combining traditional parametric surface based radiation and FD based conduction modeling with CAD and FEM methods. The use of flexible and familiar temperature solvers such as SINDA/FLUINT (Systems Improved Numerical Differencing Analyzer/Fluid Integrator) is retained.
Rashid, Norhana Mohamed; Kishi, Naoki; Soga, Tetsuo
2016-03-01
Pre-annealing as part of a two-step thermal oxidation process has a significant effect on the growth of hematite (α-Fe2O3) nanowires on Fe foil. High-density aligned nanowires were obtained on iron foils pre-annealed at 300∘C under a dry air flow for 30min. The X-ray diffraction (XRD) patterns indicate that the nanowires are transformed from the small α-Fe2O3 grains and uniquely grow in the (110) direction. The formation of a high-density of small grains by pre-annealing improved the alignment and density of the α-Fe2O3 nanowires.
Lewis, Alison E; Zhang, Yi; Gao, Peng; Nazeeruddin, Mohammad Khaja
2017-08-02
In order to achieve high-efficiency perovskite solar cells, understanding both the crystal structure and the optoelectronic properties of perovskite layers is of importance. This paper uses crystallization analysis and the modeling study of two different perovskite deposition methods (two- and one-step methods) and thereby shows that the one-step method embodies a film formation process that is dominated by crystal growth, while the dominant mechanism of the two-step procedure is nucleation. Our data based on experimental and theory shows that the one-step recipe is superior in terms of morphology control, and, hence, reproducibility, compared to the two-step recipe.
Physicochemical Properties of Jatropha Oil-Based Polyol Produced by a Two Steps Method.
Saalah, Sariah; Abdullah, Luqman Chuah; Aung, Min Min; Biak, Dayang Radiah Awang; Basri, Mahiran; Jusoh, Emiliana Rose; Mamat, Suhaini
2017-03-29
A low cost, abundant, and renewable vegetable oil source has been gaining increasing attention due to its potential to be chemically modified to polyol and thence to become an alternative replacement for the petroleum-based polyol in polyurethane production. In this study, jatropha oil-based polyol (JOL) was synthesised from non-edible jatropha oil by a two steps process, namely epoxidation and oxirane ring opening. In the first step, the effect of the reaction temperature, the molar ratio of the oil double bond to formic acid, and the reaction time on the oxirane oxygen content (OOC) of the epoxidised jatropha oil (EJO) were investigated. It was found that 4.3% OOC could be achieved with a molar ratio of 1:0.6, a reaction temperature of 60 °C, and 4 h of reaction. Consequently, a series of polyols with hydroxyl numbers in the range of 138-217 mgKOH/g were produced by oxirane ring opening of EJOs, and the physicochemical and rheological properties were studied. Both the EJOs and the JOLs are liquid and have a number average molecular weight ( M n ) in the range of 834 to 1457 g/mol and 1349 to 2129 g/mol, respectively. The JOLs exhibited Newtonian behaviour, with a low viscosity of 430-970 mPas. Finally, the JOL with a hydroxyl number of 161 mgKOH/g was further used to synthesise aqueous polyurethane dispersion, and the urethane formation was successfully monitored by Fourier Transform Infrared (FTIR).
Physicochemical Properties of Jatropha Oil-Based Polyol Produced by a Two Steps Method
Directory of Open Access Journals (Sweden)
Sariah Saalah
2017-03-01
Full Text Available A low cost, abundant, and renewable vegetable oil source has been gaining increasing attention due to its potential to be chemically modified to polyol and thence to become an alternative replacement for the petroleum-based polyol in polyurethane production. In this study, jatropha oil-based polyol (JOL was synthesised from non-edible jatropha oil by a two steps process, namely epoxidation and oxirane ring opening. In the first step, the effect of the reaction temperature, the molar ratio of the oil double bond to formic acid, and the reaction time on the oxirane oxygen content (OOC of the epoxidised jatropha oil (EJO were investigated. It was found that 4.3% OOC could be achieved with a molar ratio of 1:0.6, a reaction temperature of 60 °C, and 4 h of reaction. Consequently, a series of polyols with hydroxyl numbers in the range of 138–217 mgKOH/g were produced by oxirane ring opening of EJOs, and the physicochemical and rheological properties were studied. Both the EJOs and the JOLs are liquid and have a number average molecular weight (Mn in the range of 834 to 1457 g/mol and 1349 to 2129 g/mol, respectively. The JOLs exhibited Newtonian behaviour, with a low viscosity of 430–970 mPas. Finally, the JOL with a hydroxyl number of 161 mgKOH/g was further used to synthesise aqueous polyurethane dispersion, and the urethane formation was successfully monitored by Fourier Transform Infrared (FTIR.
International Nuclear Information System (INIS)
Casalotti, N.; Magnaud, J.P.
1989-01-01
The possibilities of the TRIO-EF software in the thermal field are presented. The TRIO-EF is a computer program based on the finite element method and used for three-dimensional incompressible flow analysis. It enables the calculation of three-dimensional heat transfer and the fluid/structure analysis. The geometrically complex radiative reactor systems are taken into account in the form factor calculation. The implemented algorithms are described [fr
A review of analysis methods about thermal buckling
International Nuclear Information System (INIS)
Moulin, D.; Combescure, A.; Acker, D.
1987-01-01
This paper highlights the main items emerging from a large bibliographical survey carried out on strain-induced buckling analysis methods applicable in the building of fast neutron reactor structures. The work is centred on the practical analysis methods used in construction codes to account for the strain-buckling of thin and slender structures. Methods proposed in the literature concerning past and present studies are rapidly described. Experimental, theoretical and numerical methods are considered. Methods applicable to design and their degree of validation are indicated
Application of heat-balance integral method to conjugate thermal explosion
Directory of Open Access Journals (Sweden)
Novozhilov Vasily
2009-01-01
Full Text Available Conjugate thermal explosion is an extension of the classical theory, proposed and studied recently by the author. The paper reports application of heat-balance integral method for developing phase portraits for systems undergoing conjugate thermal explosion. The heat-balance integral method is used as an averaging method reducing partical differential equation problem to the set of first-order ordinary differential equations. The latter reduced problem allows natural interpretation in appropriately chosen phase space. It is shown that, with the help of heat-balance integral technique, conjugate thermal explosion problem can be described with a good accuracy by the set of non-linear first-order differential equations involving complex error function. Phase trajectories are presented for typical regimes emerging in conjugate thermal explosion. Use of heat-balance integral as a spatial averaging method allows efficient description of system evolution to be developed.
Measurement of the Thermal Properties of a Metal Using a Relaxation Method
Fox, John N.; McMaster, Richard H.
1975-01-01
An undergraduate experiment is described which employs a relaxation method for the measurement of the thermal conductivity and specific heat of a metallic sample in a temperature range of 0-100 degrees centigrade. (Author/CP)
Azadmard-Damirchi, Sodeif; Dutta, Paresh C
2009-01-02
One of the crucial steps in determination of sterol oxidation products (SOPs) in foods is their enrichment and purifications by various preparative methods for further analysis by GC and GC-MS. Among the preparative methods, SPE of various adsorbents and solvent systems, are being used most widely. At present, no single step SPE method is suitable to completely separate the SOPs. In this study, a SPE (1g silica) method, suitable for both transesterified and cold saponified oil samples, was developed to separate completely SOPs from other lipid components. This method resulted in high recovery from rapeseed oil of added 5beta,6beta-epoxycholestan-3beta-ol (94-96%), cholest-5-en-3beta-ol-7-one(94%), cholestane-3beta,5alpha,6beta-triol (88-91%), cholest-5-en-3beta,7alpha-diol and 5alpha,6alpha-epoxycholestan-3beta-ol (88-90%). The method has a high sample capacity of up to 1g transesterified or cold-saponified oil sample. The method was tested and applied to different vegetable oils and to monitor the effects of refining processes on POPs in hazelnut oil.
Reisner, Sari L; Biello, Katie; Rosenberger, Joshua G; Austin, S Bryn; Haneuse, Sebastien; Perez-Brumer, Amaya; Novak, David S; Mimiaga, Matthew J
2014-11-01
Few comparative data are available internationally to examine health differences by transgender identity. A barrier to monitoring the health and well-being of transgender people is the lack of inclusion of measures to assess natal sex/gender identity status in surveys. Data were from a cross-sectional anonymous online survey of members (n > 36,000) of a sexual networking website targeting men who have sex with men in Spanish- and Portuguese-speaking countries/territories in Latin America/the Caribbean, Portugal, and Spain. Natal sex/gender identity status was assessed using a two-step method (Step 1: assigned birth sex, Step 2: current gender identity). Male-to-female (MTF) and female-to-male (FTM) participants were compared to non-transgender males in age-adjusted regression models on socioeconomic status (SES) (education, income, sex work), masculine gender conformity, psychological health and well-being (lifetime suicidality, past-week depressive distress, positive self-worth, general self-rated health, gender related stressors), and sexual health (HIV-infection, past-year STIs, past-3 month unprotected anal or vaginal sex). The two-step method identified 190 transgender participants (0.54%; 158 MTF, 32 FTM). Of the 12 health-related variables, six showed significant differences between the three groups: SES, masculine gender conformity, lifetime suicidality, depressive distress, positive self-worth, and past-year genital herpes. A two-step approach is recommended for health surveillance efforts to assess natal sex/gender identity status. Cognitive testing to formally validate assigned birth sex and current gender identity survey items in Spanish and Portuguese is encouraged.
Reisner, Sari L.; Biello, Katie; Rosenberger, Joshua G.; Austin, S. Bryn; Haneuse, Sebastien; Perez-Brumer, Amaya; Novak, David S.; Mimiaga, Matthew J.
2014-01-01
Few comparative data are available internationally to examine health differences by transgender identity. A barrier to monitoring the health and well-being of transgender people is the lack of inclusion of measures to assess natal sex/gender identity status in surveys. Data were from a cross-sectional anonymous online survey of members (n > 36,000) of a sexual networking website targeting men who have sex with men in Spanish- and Portuguese-speaking countries/ territories in Latin America/the Caribbean, Portugal, and Spain. Natal sex/gender identity status was assessed using a two-step method (Step 1: assigned birth sex, Step 2: current gender identity). Male-to-female (MTF) and female-to-male (FTM) participants were compared to non-transgender males in age-adjusted regression models on socioeconomic status (SES) (education, income, sex work), masculine gender conformity, psychological health and well-being (lifetime suicidality, past-week depressive distress, positive self-worth, general self-rated health, gender related stressors), and sexual health (HIV-infection, past-year STIs, past-3 month unprotected anal or vaginal sex). The two-step method identified 190 transgender participants (0.54%; 158 MTF, 32 FTM). Of the 12 health-related variables, six showed significant differences between the three groups: SES, masculine gender conformity, lifetime suicidality, depressive distress, positive self-worth, and past-year genital herpes. A two-step approach is recommended for health surveillance efforts to assess natal sex/gender identity status. Cognitive testing to formally validate assigned birth sex and current gender identity survey items in Spanish and Portuguese is encouraged. PMID:25030120
Turpin, Jason B.
2004-01-01
One-dimensional water-hammer modeling involves the solution of two coupled non-linear hyperbolic partial differential equations (PDEs). These equations result from applying the principles of conservation of mass and momentum to flow through a pipe, and usually the assumption that the speed at which pressure waves propagate through the pipe is constant. In order to solve these equations for the interested quantities (i.e. pressures and flow rates), they must first be converted to a system of ordinary differential equations (ODEs) by either approximating the spatial derivative terms with numerical techniques or using the Method of Characteristics (MOC). The MOC approach is ideal in that no numerical approximation errors are introduced in converting the original system of PDEs into an equivalent system of ODEs. Unfortunately this resulting system of ODEs is bound by a time step constraint so that when integrating the equations the solution can only be obtained at fixed time intervals. If the fluid system to be modeled also contains dynamic components (i.e. components that are best modeled by a system of ODEs), it may be necessary to take extremely small time steps during certain points of the model simulation in order to achieve stability and/or accuracy in the solution. Coupled together, the fixed time step constraint invoked by the MOC, and the occasional need for extremely small time steps in order to obtain stability and/or accuracy, can greatly increase simulation run times. As one solution to this problem, a method for combining variable step integration (VSI) algorithms with the MOC was developed for modeling water-hammer in systems with highly dynamic components. A case study is presented in which reverse flow through a dual-flapper check valve introduces a water-hammer event. The predicted pressure responses upstream of the check-valve are compared with test data.
Multiple Non-Thermal Reaction Steps for the Photooxidation CO to CO2 on Reduced TiO2(110)
Energy Technology Data Exchange (ETDEWEB)
Petrik, Nikolay G.; Kimmel, Gregory A.
2013-02-07
The photooxidation of CO on reduced, rutile TiO2(110) was studied on a millisecond timescale. For a saturation coverage of chemisorbed O2 (0sat) and for half that coverage, the CO2 photon-stimulated desorption (PSD) signal is initially zero, increases to a maximum after several tens of milliseconds, and then decreases at longer times. The CO2 PSD signal increases ~5 times more quickly for 0.50sat. The initial rate of increase of the CO2 PSD signal is proportional to the flux of UV photons. The intermediate species involved in the reactions is stable for at least 100 s at 30 K. These results show that two or more non-thermal reaction steps are required to photooxidize CO adsorbed on TiO2(110). In contrast, previous models had suggested that CO photooxidation required only one non-thermal reaction. The likely initial and final charge states of the system suggest that an electron-mediated reaction and a hole-mediated reaction are needed for the complete photooxidation reaction.
Methods for Aquifer Thermal Energy Storage planning; The hidden side of cities.
Jaxa-Rozen, M.; Bloemendal, M.; Theo, O.
2017-12-01
Aquifer Thermal Energy Storage (ATES) systems reduce energy use and greenhouse gas emissions in urban areas, by supplying heating and cooling to buildings with a heat pump combined with seasonal heat storage in aquifers. The climactic and geohydrological conditions required for this technology can be found in many temperate regions around the world; In The Netherlands there are currently approximately 2,200 active systems. Despite this modest adoption level, many urban areas in the Netherlands already struggle to accommodate the subsurface claims needed to further develop ATES under current planning regulations. To identify best practices for ATES planning and maximize the technology's future potential, this work first reviews a set of 24 ATES-plans which were used for the spatial layout of ATES in various urban areas in The Netherlands and the method used to make those plans. This analysis revealed that three crucial elements are found to be missing in current ATES planning: i) a consistent assessment framework which can be used to compare the performance of different planning strategies; ii) a systematic adjustment of ATES design parameters to suit local conditions; iii) the identification and use of aquifer allocation thresholds to guide the choice of a planning strategy. All three steps are elaborated and added to the method. For the latter, these thresholds are identified by exploratory numerical modelling, using a coupled agent-based/geohydrological (MODFLOW) simulation to explore a broad range of scenarios for ATES design and layout parameters. The results give insight in how technical ATES-well design choices affect optimal use of subsurface space and in the trade-of between individual efficiency and overall emission reductions. The improved ATES-planning method now fosters planning and design rules ensuring optimal and sustainable use of subsurface space, i.e. maximizing energy saving by accommodating as much ATES systems as possible while maintaining
Jajesniak, Pawel; Wong, Tuck Seng
2015-01-01
Background Molecular cloning is an essential step in biological engineering. Methods involving megaprimer-based PCR of a whole plasmid are promising alternatives to the traditional restriction-ligation-based molecular cloning. Their widespread use, however, is hampered by some of their inherent characteristics, e.g., linear amplification, use of self-annealing megaprimers and difficulty with performing point insertion of DNA. These limitations result in low product yield and reduced flexibili...
Use of a problem-based learning exercise to teach the lean 8-step problem-solving method.
Tovar, Elizabeth G; Warshawsky, Nora
2015-01-01
Doctor of nursing practice (DNP) graduates must be prepared to lead quality improvement (QI) initiatives in health care settings; however, effective and feasible teaching strategies pose a challenge for many DNP program faculties. This article describes a successful and practical problem-based learning exercise for students to work through the QI process using the Lean 8-step problem-solving method. Suggestions for faculty and recommendations for future activities are discussed.
DEFF Research Database (Denmark)
Swierczynski, Maciej Jozef; Stroe, Daniel Loan; Stanciu, Tiberiu
-ion battery cells and battery packs is gaining importance. Equivalent thermal circuits’ models have proven to be relatively accurate with low computational burden for the price of low spatial resolution; nevertheless, they usually require expensive equipment for parametrization. Recent research initiated...... by Barsoukov et al. proposed electrothermal impedance spectroscopy (ETIS) as a novel and non-destructive method of characterizing the thermal properties of batteries by defining frequency dependent thermal impedance. This paper aims to systematize the state of knowledge about ETIS, presents measurement methods...
Single-step method of RNA isolation by acid guanidinium thiocyanate-phenol-chloroform extraction.
Chomczynski, P; Sacchi, N
1987-04-01
A new method of total RNA isolation by a single extraction with an acid guanidinium thiocyanate-phenol-chloroform mixture is described. The method provides a pure preparation of undegraded RNA in high yield and can be completed within 4 h. It is particularly useful for processing large numbers of samples and for isolation of RNA from minute quantities of cells or tissue samples.
Ha, Sanghyun; Park, Junshin; You, Donghyun
2018-01-01
Utility of the computational power of Graphics Processing Units (GPUs) is elaborated for solutions of incompressible Navier-Stokes equations which are integrated using a semi-implicit fractional-step method. The Alternating Direction Implicit (ADI) and the Fourier-transform-based direct solution methods used in the semi-implicit fractional-step method take advantage of multiple tridiagonal matrices whose inversion is known as the major bottleneck for acceleration on a typical multi-core machine. A novel implementation of the semi-implicit fractional-step method designed for GPU acceleration of the incompressible Navier-Stokes equations is presented. Aspects of the programing model of Compute Unified Device Architecture (CUDA), which are critical to the bandwidth-bound nature of the present method are discussed in detail. A data layout for efficient use of CUDA libraries is proposed for acceleration of tridiagonal matrix inversion and fast Fourier transform. OpenMP is employed for concurrent collection of turbulence statistics on a CPU while the Navier-Stokes equations are computed on a GPU. Performance of the present method using CUDA is assessed by comparing the speed of solving three tridiagonal matrices using ADI with the speed of solving one heptadiagonal matrix using a conjugate gradient method. An overall speedup of 20 times is achieved using a Tesla K40 GPU in comparison with a single-core Xeon E5-2660 v3 CPU in simulations of turbulent boundary-layer flow over a flat plate conducted on over 134 million grids. Enhanced performance of 48 times speedup is reached for the same problem using a Tesla P100 GPU.
International Nuclear Information System (INIS)
Wu, Xiaoguang; Zhao, Xu; Li, Yi; Yang, Tao; Yan, Xiujuan; Wang, Ke
2015-01-01
In situ fabrication of carbonated hydroxyapatite (CHA) remineralization layer on an enamel slice was completed in a novel, biomimetic two-step method. First, a CaCO 3 layer was synthesized on the surface of demineralized enamel using an acidic amino acid (aspartic acid or glutamate acid) as a soft template. Second, at the same concentration of the acidic amino acid, rod-like carbonated hydroxyapatite was produced with the CaCO 3 layer as a sacrificial template and a reactant. The morphology, crystallinity and other physicochemical properties of the crystals were characterized using field emission scanning electron microscopy (FESEM), Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD) and energy-dispersive X-ray analysis (EDAX), respectively. Acidic amino acid could promote the uniform deposition of hydroxyapatite with rod-like crystals via absorption of phosphate and carbonate ions from the reaction solution. Moreover, compared with hydroxyapatite crystals coated on the enamel when synthesized by a one-step method, the CaCO 3 coating that was synthesized in the first step acted as an active bridge layer and sacrificial template. It played a vital role in orienting the artificial coating layer through the template effect. The results show that the rod-like carbonated hydroxyapatite crystals grow into bundles, which are similar in size and appearance to prisms in human enamel, when using the two-step method with either aspartic acid or acidic glutamate (20.00 mmol/L). - Graphical abstract: FESEM images of enamel slices etched for 60 s and repaired by the two-step method with Glu concentration of 20.00 mmol/L. (A) The boundary (dotted line) of the repaired areas (b) and unrepaired areas (a). (Some selected areas of etched enamel slices were coated with a nail polish before the reaction, which was removed by acetone after the reaction); (B) high magnification image of Ga, (C) high magnification image of Gb. In situ fabrication of carbonated
Energy Technology Data Exchange (ETDEWEB)
Wu, Xiaoguang [Department of Pediatric Dentistry, The Hospital of Stomatology, Jilin University, Changchun 130021 (China); Zhao, Xu [College of Chemistry, Jilin University, Changchun 130021 (China); Li, Yi, E-mail: lyi99@jlu.edu.cn [Department of Pediatric Dentistry, The Hospital of Stomatology, Jilin University, Changchun 130021 (China); Yang, Tao [Department of Stomatology, Children' s Hospital of Changchun, 130051 (China); Yan, Xiujuan; Wang, Ke [Department of Pediatric Dentistry, The Hospital of Stomatology, Jilin University, Changchun 130021 (China)
2015-09-01
In situ fabrication of carbonated hydroxyapatite (CHA) remineralization layer on an enamel slice was completed in a novel, biomimetic two-step method. First, a CaCO{sub 3} layer was synthesized on the surface of demineralized enamel using an acidic amino acid (aspartic acid or glutamate acid) as a soft template. Second, at the same concentration of the acidic amino acid, rod-like carbonated hydroxyapatite was produced with the CaCO{sub 3} layer as a sacrificial template and a reactant. The morphology, crystallinity and other physicochemical properties of the crystals were characterized using field emission scanning electron microscopy (FESEM), Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD) and energy-dispersive X-ray analysis (EDAX), respectively. Acidic amino acid could promote the uniform deposition of hydroxyapatite with rod-like crystals via absorption of phosphate and carbonate ions from the reaction solution. Moreover, compared with hydroxyapatite crystals coated on the enamel when synthesized by a one-step method, the CaCO{sub 3} coating that was synthesized in the first step acted as an active bridge layer and sacrificial template. It played a vital role in orienting the artificial coating layer through the template effect. The results show that the rod-like carbonated hydroxyapatite crystals grow into bundles, which are similar in size and appearance to prisms in human enamel, when using the two-step method with either aspartic acid or acidic glutamate (20.00 mmol/L). - Graphical abstract: FESEM images of enamel slices etched for 60 s and repaired by the two-step method with Glu concentration of 20.00 mmol/L. (A) The boundary (dotted line) of the repaired areas (b) and unrepaired areas (a). (Some selected areas of etched enamel slices were coated with a nail polish before the reaction, which was removed by acetone after the reaction); (B) high magnification image of Ga, (C) high magnification image of Gb. In situ fabrication of
Directory of Open Access Journals (Sweden)
Ermuratschii V.V.
2014-04-01
Full Text Available e paper presents a method of the approximate calculation of the non-stationary temperature field inside of thermal packed bed energy storages with feasible and latent heat. Applying thermoelectric models and computational methods in electrical engineering, the task of computing non-stationary heat transfer is resolved with respect to third type boundary conditions without applying differential equations of the heat transfer. For sub-volumes of the energy storage the method is executed iteratively in spatiotemporal domain. Single-body heating is modeled for each sub-volume, and modeling conditions are assumed to be identical for remained bod-ies, located in the same sub-volume. For each iteration step the boundary conditions will be represented by re-sults at the previous step. The fulfillment of the first law of thermodynamics for system “energy storage - body” is obtained by the iterative search of the mean temperature of the energy storage. Under variable boundary con-ditions the proposed method maybe applied to calculating temperature field inside of energy storages with packed beds consisted of solid material, liquid and phase-change material. The method may also be employed to compute transient, power and performance characteristics of packed bed energy storages.
An extended step characteristic method for solving the transport equation in general geometries
International Nuclear Information System (INIS)
DeHart, M.D.; Pevey, R.E.; Parish, T.A.
1994-01-01
A method for applying the discrete ordinates method to solve the Boltzmann transport equation on arbitrary two-dimensional meshes has been developed. The finite difference approach normally used to approximate spatial derivatives in extrapolating angular fluxes across a cell is replaced by direct solution of the characteristic form of the transport equation for each discrete direction. Thus, computational cells are not restricted to the geometrical shape of a mesh element characteristic of a given coordinate system. However, in terms of the treatment of energy and angular dependencies, this method resembles traditional discrete ordinates techniques. By using the method developed here, a general two-dimensional space can be approximated by an irregular mesh comprised of arbitrary polygons. Results for a number of test problems have been compared with solutions obtained from traditional methods, with good agreement. Comparisons include benchmarks against analytical results for problems with simple geometry, as well as numerical results obtained from traditional discrete ordinates methods by applying the ANISN and TWOTRAN-II computer programs
Wu, Xiaoguang; Zhao, Xu; Li, Yi; Yang, Tao; Yan, Xiujuan; Wang, Ke
2015-09-01
In situ fabrication of carbonated hydroxyapatite (CHA) remineralization layer on an enamel slice was completed in a novel, biomimetic two-step method. First, a CaCO3 layer was synthesized on the surface of demineralized enamel using an acidic amino acid (aspartic acid or glutamate acid) as a soft template. Second, at the same concentration of the acidic amino acid, rod-like carbonated hydroxyapatite was produced with the CaCO3 layer as a sacrificial template and a reactant. The morphology, crystallinity and other physicochemical properties of the crystals were characterized using field emission scanning electron microscopy (FESEM), Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD) and energy-dispersive X-ray analysis (EDAX), respectively. Acidic amino acid could promote the uniform deposition of hydroxyapatite with rod-like crystals via absorption of phosphate and carbonate ions from the reaction solution. Moreover, compared with hydroxyapatite crystals coated on the enamel when synthesized by a one-step method, the CaCO3 coating that was synthesized in the first step acted as an active bridge layer and sacrificial template. It played a vital role in orienting the artificial coating layer through the template effect. The results show that the rod-like carbonated hydroxyapatite crystals grow into bundles, which are similar in size and appearance to prisms in human enamel, when using the two-step method with either aspartic acid or acidic glutamate (20.00 mmol/L). Copyright © 2015 Elsevier B.V. All rights reserved.
Reliability residual-life prediction method for thermal aging based on performance degradation
International Nuclear Information System (INIS)
Ren Shuhong; Xue Fei; Yu Weiwei; Ti Wenxin; Liu Xiaotian
2013-01-01
The paper makes the study of the nuclear power plant main pipeline. The residual-life of the main pipeline that failed due to thermal aging has been studied by the use of performance degradation theory and Bayesian updating methods. Firstly, the thermal aging impact property degradation process of the main pipeline austenitic stainless steel has been analyzed by the accelerated thermal aging test data. Then, the thermal aging residual-life prediction model based on the impact property degradation data is built by Bayesian updating methods. Finally, these models are applied in practical situations. It is shown that the proposed methods are feasible and the prediction accuracy meets the needs of the project. Also, it provides a foundation for the scientific management of aging management of the main pipeline. (authors)
A new method for measuring the thermal regulatory properties of phase change material (PCM) fabrics
International Nuclear Information System (INIS)
Wan, X; Fan, J
2009-01-01
Several methods already exist for the measurement of the thermal regulatory properties of fabrics containing phase change materials (PCMs). However, they do not adequately simulate the actual use condition; consequently the measurements may not have relevance to the performance of PCM fabrics in actual use. Here we report on the development of a new method, which better simulates the real use situation. In this method, a hot plate, simulating the human body, generates a constant amount of heat depending on the type of human activity to be simulated. The hot plate covered by the PCM fabric is then exposed to a thermal transient simulating a wearer moving from one thermal environment to another; the changes of surface temperature and heat loss of the hot plate are then recorded and used to characterize the thermal regulatory properties of the PCM fabrics
American Society for Testing and Materials. Philadelphia
2008-01-01
1.1 The purpose of this test method is to define a general procedure for determining an unknown thermal-neutron fluence rate by neutron activation techniques. It is not practicable to describe completely a technique applicable to the large number of experimental situations that require the measurement of a thermal-neutron fluence rate. Therefore, this method is presented so that the user may adapt to his particular situation the fundamental procedures of the following techniques. 1.1.1 Radiometric counting technique using pure cobalt, pure gold, pure indium, cobalt-aluminum, alloy, gold-aluminum alloy, or indium-aluminum alloy. 1.1.2 Standard comparison technique using pure gold, or gold-aluminum alloy, and 1.1.3 Secondary standard comparison techniques using pure indium, indium-aluminum alloy, pure dysprosium, or dysprosium-aluminum alloy. 1.2 The techniques presented are limited to measurements at room temperatures. However, special problems when making thermal-neutron fluence rate measurements in high-...
Outcrop samples from Forsmark. Determination of thermal properties by the TPS-Method
Energy Technology Data Exchange (ETDEWEB)
Adl-Zarrabi, Bijan [Swedish National Testing and Research Inst., Boras (Sweden)
2003-04-01
Porosity, density and thermal properties were measured for five different outcrop samples from Forsmark namely: two samples of Metatonalit, Metadiorit, Metagranit and Metagranodiorit. Measurements were performed according to SKB's method descriptions SKB MD 191.001 (Determination of thermal properties, thermal conductivity and specific heat, by using TPS-method) and SKB MD 160.002 ( Determination of density and porosity of the intact rocks). In addition to material properties, the influence of orientation on thermal properties was investigated. The amount of material delivered was too small to produce all needed samples for measurement of thermal properties and determination of the influence of orientation. Thus the influence of orientation on thermal properties was not made in accordance with SKB MD 191.001. The influence of orientation is determined by using a single sided method, which gives the relative relation between two major orientations of the rock. Results obtained by these measurements were in the expected normal variation range. The results indicated that the samples of Metatonalit (MBS020002b) and Metagranit behaved as an anisotropic material (the difference between orientations was about 20-24%) and the samples made of Metatonalit (MBS020002b) and Metagranodiorit could be assumed as an isotropic material (the difference between orientations was about 0.5-2%). The difference in thermal properties of different orientation in sample Metadiorit is about 13%.
Directory of Open Access Journals (Sweden)
Seswoya Roslinda
2016-01-01
Full Text Available In practice, primary and secondary sludge are fed into anaerobic digestion. However, the microbial cell exists in secondary sludge are an unfavorable substrate for biodegradation. Thermal pretreatment is proved to increase the bioavailability of organic and improve the biodegradation subsequently. During low thermal pretreatment, both intracellular (within the microbial cell and extracellular (within the polymeric network materials were extracted. This process increases the bioavailability meaning that organic compounds are accessible to the microorganisms for their degradation. This research aims to investigate the effect of thermal pretreatment on domestic mixed sludge disintegration. Domestic mixed sludge was thermally treated at 70°C for various holding times. The pre-thermally treated domestic mixed sludge was measured for protein and carbohydrates following the Lowry Method, and Phenol-Sulphuric Acid Method respectively. DR 6000 UV-Vis spectrophotometer, DRB200 Reactor (digester and COD vial (TNT plus 822 were used for COD determination, based on Reactor Digestion Method approved by USEPA. The results showed that the organic matter in domestic mixed sludge is efficiently solubilised during thermal treatment organic matter. The higher soluble yield for each monitored parameter determined in this study indicated that low thermal pretreatment improve bioavailability.
Outcrop samples from Forsmark. Determination of thermal properties by the TPS-Method
International Nuclear Information System (INIS)
Adl-Zarrabi, Bijan
2003-04-01
Porosity, density and thermal properties were measured for five different outcrop samples from Forsmark namely: two samples of Metatonalit, Metadiorit, Metagranit and Metagranodiorit. Measurements were performed according to SKB's method descriptions SKB MD 191.001 (Determination of thermal properties, thermal conductivity and specific heat, by using TPS-method) and SKB MD 160.002 ( Determination of density and porosity of the intact rocks). In addition to material properties, the influence of orientation on thermal properties was investigated. The amount of material delivered was too small to produce all needed samples for measurement of thermal properties and determination of the influence of orientation. Thus the influence of orientation on thermal properties was not made in accordance with SKB MD 191.001. The influence of orientation is determined by using a single sided method, which gives the relative relation between two major orientations of the rock. Results obtained by these measurements were in the expected normal variation range. The results indicated that the samples of Metatonalit (MBS020002b) and Metagranit behaved as an anisotropic material (the difference between orientations was about 20-24%) and the samples made of Metatonalit (MBS020002b) and Metagranodiorit could be assumed as an isotropic material (the difference between orientations was about 0.5-2%). The difference in thermal properties of different orientation in sample Metadiorit is about 13%
Solar panel thermal cycling testing by solar simulation and infrared radiation methods
Nuss, H. E.
1980-01-01
For the solar panels of the European Space Agency (ESA) satellites OTS/MAROTS and ECS/MARECS the thermal cycling tests were performed by using solar simulation methods. The performance data of two different solar simulators used and the thermal test results are described. The solar simulation thermal cycling tests for the ECS/MARECS solar panels were carried out with the aid of a rotatable multipanel test rig by which simultaneous testing of three solar panels was possible. As an alternative thermal test method, the capability of an infrared radiation method was studied and infrared simulation tests for the ultralight panel and the INTELSAT 5 solar panels were performed. The setup and the characteristics of the infrared radiation unit using a quartz lamp array of approx. 15 sq and LN2-cooled shutter and the thermal test results are presented. The irradiation uniformity, the solar panel temperature distribution, temperature changing rates for both test methods are compared. Results indicate the infrared simulation is an effective solar panel thermal testing method.
Detection of Heterogeneous Small Inclusions by a Multi-Step MUSIC Method
Solimene, Raffaele; Dell'Aversano, Angela; Leone, Giovanni
2014-05-01
In this contribution the problem of detecting and localizing scatterers with small (in terms of wavelength) cross sections by collecting their scattered field is addressed. The problem is dealt with for a two-dimensional and scalar configuration where the background is given as a two-layered cylindrical medium. More in detail, while scattered field data are taken in the outermost layer, inclusions are embedded within the inner layer. Moreover, the case of heterogeneous inclusions (i.e., having different scattering coefficients) is addressed. As a pertinent applicative context we identify the problem of diagnose concrete pillars in order to detect and locate rebars, ducts and other small in-homogeneities that can populate the interior of the pillar. The nature of inclusions influences the scattering coefficients. For example, the field scattered by rebars is stronger than the one due to ducts. Accordingly, it is expected that the more weakly scattering inclusions can be difficult to be detected as their scattered fields tend to be overwhelmed by those of strong scatterers. In order to circumvent this problem, in this contribution a multi-step MUltiple SIgnal Classification (MUSIC) detection algorithm is adopted [1]. In particular, the first stage aims at detecting rebars. Once rebars have been detected, their positions are exploited to update the Green's function and to subtract the scattered field due to their presence. The procedure is repeated until all the inclusions are detected. The analysis is conducted by numerical experiments for a multi-view/multi-static single-frequency configuration and the synthetic data are generated by a FDTD forward solver. Acknowledgement This work benefited from networking activities carried out within the EU funded COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar." [1] R. Solimene, A. Dell'Aversano and G. Leone, "MUSIC algorithms for rebar detection," J. of Geophysics and Engineering, vol. 10, pp. 1
Transient thermal analysis as measurement method for IC package structural integrity
Hanß, Alexander; Schmid, Maximilian; Liu, E.; Elger, Gordon
2015-06-01
Practices of IC package reliability testing are reviewed briefly, and the application of transient thermal analysis is examined in great depth. For the design of light sources based on light emitting diode (LED) efficient and accurate reliability testing is required to realize the potential lifetimes of 105 h. Transient thermal analysis is a standard method to determine the transient thermal impedance of semiconductor devices, e.g. power electronics and LEDs. The temperature of the semiconductor junctions is assessed by time-resolved measurement of their forward voltage (Vf). The thermal path in the IC package is resolved by the transient technique in the time domain. This enables analyzing the structural integrity of the semiconductor package. However, to evaluate thermal resistance, one must also measure the dissipated energy of the device (i.e., the thermal load) and the k-factor. This is time consuming, and measurement errors reduce the accuracy. To overcome these limitations, an innovative approach, the relative thermal resistance method, was developed to reduce the measurement effort, increase accuracy and enable automatic data evaluation. This new way of evaluating data simplifies the thermal transient analysis by eliminating measurement of the k-factor and thermal load, i.e. measurement of the lumen flux for LEDs, by normalizing the transient Vf data. This is especially advantageous for reliability testing where changes in the thermal path, like cracks and delaminations, can be determined without measuring the k-factor and thermal load. Different failure modes can be separated in the time domain. The sensitivity of the method is demonstrated by its application to high-power white InGaN LEDs. For detailed analysis and identification of the failure mode of the LED packages, the transient signals are simulated by time-resolved finite element (FE) simulations. Using the new approach, the transient thermal analysis is enhanced to a powerful tool for reliability
The next step in coastal numerical models: spectral/hp element methods?
DEFF Research Database (Denmark)
Eskilsson, Claes; Engsig-Karup, Allan Peter; Sherwin, Spencer J.
2005-01-01
In this paper we outline the application of spectral/hp element methods for modelling nonlinear and dispersive waves. We present one- and two-dimensional test cases for the shallow water equations and Boussinesqtype equations – including highly dispersive Boussinesq-type equations.......In this paper we outline the application of spectral/hp element methods for modelling nonlinear and dispersive waves. We present one- and two-dimensional test cases for the shallow water equations and Boussinesqtype equations – including highly dispersive Boussinesq-type equations....
Directory of Open Access Journals (Sweden)
Katarzyna Kalinowska-Wichrowska
2018-04-01
Full Text Available The article contains the data on the state of natural aggregate resources and attention has been paid to the enormous scale of the production of concrete and produced rubble-concrete waste in the world. The methods of recycling concrete debris used in the world along with their subjective assessment are presented in the paper. The legal regulations on concrete recycling defined by the European Union and Polish law are briefly characterized. The use of an appropriately effective method of recycling concrete debris allows obtaining a high quality secondary aggregate, which can be reused for the production of new concrete and reduces the consumption of natural aggregates.
Ha, Sanghyun; Park, Junshin; You, Donghyun
2017-11-01
Utility of the computational power of modern Graphics Processing Units (GPUs) is elaborated for solutions of incompressible Navier-Stokes equations which are integrated using a semi-implicit fractional-step method. Due to its serial and bandwidth-bound nature, the present choice of numerical methods is considered to be a good candidate for evaluating the potential of GPUs for solving Navier-Stokes equations using non-explicit time integration. An efficient algorithm is presented for GPU acceleration of the Alternating Direction Implicit (ADI) and the Fourier-transform-based direct solution method used in the semi-implicit fractional-step method. OpenMP is employed for concurrent collection of turbulence statistics on a CPU while Navier-Stokes equations are computed on a GPU. Extension to multiple NVIDIA GPUs is implemented using NVLink supported by the Pascal architecture. Performance of the present method is experimented on multiple Tesla P100 GPUs compared with a single-core Xeon E5-2650 v4 CPU in simulations of boundary-layer flow over a flat plate. Supported by the National Research Foundation of Korea (NRF) Grant funded by the Korea government (Ministry of Science, ICT and Future Planning NRF-2016R1E1A2A01939553, NRF-2014R1A2A1A11049599, and Ministry of Trade, Industry and Energy 201611101000230).
Popescu, Maria-Cristina; Popescu, Carmen-Mihaela; Lisa, Gabriela; Sakata, Yusaku
2011-03-01
The aim of this study is to find the most convenient procedure to make an easy differentiation between various kinds of wood. The wood samples used were: fir (Acer alba), poplar (Populus tremula), lime (Tillia cordata), sycamore (Acer pseudoplatanus), sweet cherry (Prunus avium), hornbeam (Carpinus betulus), walnut (Juglans regia), beech (Fagus sylvatica), oak (Quercus robur). The methods of investigation used were FT-IR spectroscopy, X-ray diffraction and thermogravimetry. By FT-IR spectroscopy, was observed that the ratio values of lignin/carbohydrate IR bands for wood decreases with increasing the average wood density, showing a decrease in lignin content. Also, the calculated values of lignin percentage from the FT-IR spectra are in very good correlation with the values from literature. Following the deconvolution process of the X-ray diffraction patterns, it was found that the degree of crystallinity, the apparent lateral crystallite size, the proportion of crystallite interior chains and cellulose fraction tend to increase with increasing of the wood density. Thermal analysis is able to give information about degradation temperatures for the principal components of different wood samples. The shape of DTG curves depends on the wood species that cause the enlargement of the peaks or the maxima of the decomposition step varies at larger or smaller temperatures ranges. The temperatures and weight loss percentage are particular for each kind of wood. This study showed that analytical methods used have the potential to be important sources of information for a quick evaluation of the chemical composition of wood samples.
Method and Process Development of Advanced Atmospheric Plasma Spraying for Thermal Barrier Coatings
Mihm, Sebastian; Duda, Thomas; Gruner, Heiko; Thomas, Georg; Dzur, Birger
2012-06-01
Over the last few years, global economic growth has triggered a dramatic increase in the demand for resources, resulting in steady rise in prices for energy and raw materials. In the gas turbine manufacturing sector, process optimizations of cost-intensive production steps involve a heightened potential of savings and form the basis for securing future competitive advantages in the market. In this context, the atmospheric plasma spraying (APS) process for thermal barrier coatings (TBC) has been optimized. A constraint for the optimization of the APS coating process is the use of the existing coating equipment. Furthermore, the current coating quality and characteristics must not change so as to avoid new qualification and testing. Using experience in APS and empirically gained data, the process optimization plan included the variation of e.g. the plasma gas composition and flow-rate, the electrical power, the arrangement and angle of the powder injectors in relation to the plasma jet, the grain size distribution of the spray powder and the plasma torch movement procedures such as spray distance, offset and iteration. In particular, plasma properties (enthalpy, velocity and temperature), powder injection conditions (injection point, injection speed, grain size and distribution) and the coating lamination (coating pattern and spraying distance) are examined. The optimized process and resulting coating were compared to the current situation using several diagnostic methods. The improved process significantly reduces costs and achieves the requirement of comparable coating quality. Furthermore, a contribution was made towards better comprehension of the APS of ceramics and the definition of a better method for future process developments.
A direct differential method for measuring thermal conductivity of thin films
Zeng, Yuqiang; Marconnet, Amy
2017-04-01
Over the past two decades, significant progress in the thermal metrology for thin films and wires has enabled new understanding of the thermal conductivity of nanostructures. However, a large variation in the measured thermal conductivity of similar nanostructured samples has been observed. In addition to potential differences from sample-to-sample, measurement uncertainty contributes to the observed variation in measured properties. Many now standard micro/nanoscale thermal measurement techniques require extensive calibration of the properties of the substrate and support structures and this calibration contributes to uncertainty. Within this work, we develop a simple, direct differential electrothermal measurement of thermal conductivity of micro/nanoscale sample films by extending conventional steady state electrothermal approaches. Specifically, we leverage a cross-beam measurement structure consisting of a suspended, composite heater beam (metal on silicon) with the sample structure (silicon) extending at a right angle from the center of the heater beam, in a configuration similar to the T-type measurements used for fibers and nanotubes. To accurately resolve the thermal conductivity of the sample, the steady-state Joule heating response of the cross-beam structure is measured. Then, the sample is detached from the heater beam with a Focused Ion Beam (FIB) tool enabling direct characterization of the composite heater beam thermal properties. The differential measurement of the structure before and after FIB cut enables direct extraction of the sample thermal conductivity. The effectiveness of this differential measurement technique is demonstrated by measuring thermal conductivity of a 200 nm silicon layer. Additionally, this new method enables investigation of the accuracy of conventional approaches for extracting sample thermal conductivity with the composite beam structure and conventional comparative approaches. The results highlight the benefits of the
A direct differential method for measuring thermal conductivity of thin films.
Zeng, Yuqiang; Marconnet, Amy
2017-04-01
Over the past two decades, significant progress in the thermal metrology for thin films and wires has enabled new understanding of the thermal conductivity of nanostructures. However, a large variation in the measured thermal conductivity of similar nanostructured samples has been observed. In addition to potential differences from sample-to-sample, measurement uncertainty contributes to the observed variation in measured properties. Many now standard micro/nanoscale thermal measurement techniques require extensive calibration of the properties of the substrate and support structures and this calibration contributes to uncertainty. Within this work, we develop a simple, direct differential electrothermal measurement of thermal conductivity of micro/nanoscale sample films by extending conventional steady state electrothermal approaches. Specifically, we leverage a cross-beam measurement structure consisting of a suspended, composite heater beam (metal on silicon) with the sample structure (silicon) extending at a right angle from the center of the heater beam, in a configuration similar to the T-type measurements used for fibers and nanotubes. To accurately resolve the thermal conductivity of the sample, the steady-state Joule heating response of the cross-beam structure is measured. Then, the sample is detached from the heater beam with a Focused Ion Beam (FIB) tool enabling direct characterization of the composite heater beam thermal properties. The differential measurement of the structure before and after FIB cut enables direct extraction of the sample thermal conductivity. The effectiveness of this differential measurement technique is demonstrated by measuring thermal conductivity of a 200 nm silicon layer. Additionally, this new method enables investigation of the accuracy of conventional approaches for extracting sample thermal conductivity with the composite beam structure and conventional comparative approaches. The results highlight the benefits of the
A Ten-Step Design Method for Simulation Games in Logistics Management
Fumarola, M.; Van Staalduinen, J.P.; Verbraeck, A.
2011-01-01
Simulation games have often been found useful as a method of inquiry to gain insight in complex system behavior and as aids for design, engineering simulation and visualization, and education. Designing simulation games are the result of creative thinking and planning, but often not the result of a
A two-step method for forecasting spare parts demand using information on component repairs
Romeijnders, Ward; Teunter, Ruud; van Jaarsveld, Willem
2012-01-01
Forecasting spare parts demand is notoriously difficult, as demand is typically intermittent and lumpy. Specialized methods such as that by Croston are available, but these are not based on the repair operations that cause the intermittency and lumpiness of demand. In this paper, we do propose a
Method to make a single-step etch mask for 3D monolithic nanostructures
Grishina, Diana; Harteveld, Cornelis A.M.; Woldering, L.A.; Vos, Willem L.
2015-01-01
Current nanostructure fabrication by etching is usually limited to planar structures as they are defined by a planar mask. The realization of three-dimensional (3D) nanostructures by etching requires technologies beyond planar masks. We present a method for fabricating a 3D mask that allows one to
Synthesis of large CZTSe nanoparticles through a two-step hot-injection method
DEFF Research Database (Denmark)
Engberg, Sara Lena Josefin; Li, Zhenggang; Lek, Jun Yan
2015-01-01
Grain boundaries in Cu2ZnSn(SxSe1x)4 (CZTSSe) thin films act as a defect that reduces the mobility of the charges. Hence one way to improve the performance of these thin film solar cells is to increase the grain size in the films. Most of the synthesis methods published so far for CZTSSe colloidal...
Evaluation of the wheel-point and step-point methods of veld ...
African Journals Online (AJOL)
Using a circular-quadrat 3,5 cm in diameter yielded a more precise index of basal cover than did the standard method using a point-quadrat 1 mm in diameter. However, there are disadvantages in using the relatively large quadrat. Possible bias introduced into determining percentage species composition and composition ...
Stepping beyond the paradigm wars: pluralist methods for research in learning technology
Directory of Open Access Journals (Sweden)
Chris Jones
2011-02-01
Full Text Available This paper outlines a problem we have found in our own practice when we have been developing new researchers at post-graduate level. When students begin research training and practice, they are often confused between different levels of thinking when they are faced with methods, methodologies and research paradigms. We argue that this confusion arises from the way research methods are taught, embedded and embodied in educational systems. We set out new ways of thinking about levels of research in the field of learning technology. We argue for a problem driven/pragmatic approach to research and consider the range of methods that can be applied as diverse lenses to particular research problems. The problem of developing a coherent approach to research and research methods is not confined to research in learning technology because it is arguably a problem for all educational research and one that also affects an even wider range of disciplinary and interdisciplinary subject areas. For the purposes of this paper we will discuss the problem in relation to research in learning technologies and make a distinction between developmental and basic research that we think is particularly relevant in this field. The paradigms of research adopted have real consequences for the ways research problems are conceived and articulated, and the ways in which research is conducted. This has become an even more pressing concern in the challenging funding climate that researchers now face. We argue that there is not a simple 1 to 1 relationship between levels and most particularly that there usually is not a direct association of particular methods with either a philosophical outlook or paradigm of research. We conclude by recommending a pluralist approach to thinking about research problems and we illustrate this with the suggestion that we should encourage researchers to think in terms of counterpositives. If the researcher suggests one way of doing research in an
A method for statistical steady state thermal analysis of reactor cores
International Nuclear Information System (INIS)
Whetton, P.A.
1980-01-01
This paper presents a method for performing a statistical steady state thermal analysis of a reactor core. The technique is only outlined here since detailed thermal equations are dependent on the core geometry. The method has been applied to a pressurised water reactor core and the results are presented for illustration purposes. Random hypothetical cores are generated using the Monte-Carlo method. The technique shows that by splitting the parameters into two types, denoted core-wise and in-core, the Monte Carlo method may be used inexpensively. The idea of using extremal statistics to characterise the low probability events (i.e. the tails of a distribution) is introduced together with a method of forming the final probability distribution. After establishing an acceptable probability of exceeding a thermal design criterion, the final probability distribution may be used to determine the corresponding thermal response value. If statistical and deterministic (i.e. conservative) thermal response values are compared, information on the degree of pessimism in the deterministic method of analysis may be inferred and the restrictive performance limitations imposed by this method relieved. (orig.)
Teaching Thermal Hydraulics & Numerical Methods: An Introductory Control Volume Primer
Energy Technology Data Exchange (ETDEWEB)
Lucas, D.S.
2004-10-03
This paper covers the basics of the implementation of the control volume method in the context of the Homogeneous Equilibrium Model (HEM)(T/H) code using the conservation equations of mass, momentum, and energy. This primer uses the advection equation as a template. The discussion will cover the basic equations of the control volume portion of the course in the primer, which includes the advection equation, numerical methods, along with the implementation of the various equations via FORTRAN into computer programs and the final result for a three equation HEM code and its validation.
A Temperature Sensor Clustering Method for Thermal Error Modeling of Heavy Milling Machine Tools
Directory of Open Access Journals (Sweden)
Fengchun Li
2017-01-01
Full Text Available A clustering method is an effective way to select the proper temperature sensor location for thermal error modeling of machine tools. In this paper, a new temperature sensor clustering method is proposed. By analyzing the characteristics of the temperature of the sensors in a heavy floor-type milling machine tool, an indicator involving both the Euclidean distance and the correlation coefficient was proposed to reflect the differences between temperature sensors, and the indicator was expressed by a distance matrix to be used for hierarchical clustering. Then, the weight coefficient in the distance matrix and the number of the clusters (groups were optimized by a genetic algorithm (GA, and the fitness function of the GA was also rebuilt by establishing the thermal error model at one rotation speed, then deriving its accuracy at two different rotation speeds with a temperature disturbance. Thus, the parameters for clustering, as well as the final selection of the temperature sensors, were derived. Finally, the method proposed in this paper was verified on a machine tool. According to the selected temperature sensors, a thermal error model of the machine tool was established and used to predict the thermal error. The results indicate that the selected temperature sensors can accurately predict thermal error at different rotation speeds, and the proposed temperature sensor clustering method for sensor selection is expected to be used for the thermal error modeling for other machine tools.
Félix, V; Jannot, Y; Degiovanni, A
2012-05-01
Standard pore size determination methods such as mercury porosimetry, nitrogen sorption, microscopy, or x-ray tomography are not always applicable to highly porous, low density, and thus very fragile materials. For this kind of materials, a method based on thermal characterization is proposed. Indeed, the thermal conductivity of a highly porous and insulating medium is significantly dependent on the thermal conductivity of the interstitial gas that depends on both gas pressure and size of the considered pore (Knudsen effect). It is also possible to link the pore size with the thermal conductivity of the medium. Thermal conductivity measurements are realized on specimens placed in an enclosure where the air pressure is successively set to different values varying from 10(-1) to 10(5) Pa. Knowing the global porosity ratio, an effective thermal conductivity model for a two-phase air-solid material based on a combined serial-parallel model is established. Pore size distribution can be identified by minimizing the sum of the quadratic differences between measured values and modeled ones. The results of the estimation process are the volume fractions of the chosen ranges of pore size. In order to validate the method, measurements done on insulating materials are presented. The results are discussed and show that pore size distribution estimated by the proposed method is coherent.
An efficient method combining thermal annealing and acid leaching ...
Indian Academy of Sciences (India)
Thus obtained silica was investigated by inductively coupled plasma atomic emission spectrometry (ICP–AES) method. Major impurities present in silica sand were Al, K, Fe, Na, Ca, Mg and B. Among the new products, almost major impurities were removed effectively. Indeed purity degree, given by characterization of ...
Pseudo-harmonics method: an application to thermal reactors
International Nuclear Information System (INIS)
Silva, F.C. da; Rotenberg, S.; Thome Filho, Z.D.
1985-10-01
Several applications of the Pseudo-Harmonics method are presented, aiming to calculate the neutron flux and the perturbed eigenvalue of a nuclear reactor, like PWR, with three enrichment regions as Angra-1 reactor. In the reference reactor, perturbations of several types as global as local were simulated. The results were compared with those from the direct calculation. (E.G.) [pt
Inverse thermal analysis method to study solidification in cast iron
DEFF Research Database (Denmark)
Dioszegi, Atilla; Hattel, Jesper
2004-01-01
to achieve a stable convergence. The heat transfer problem is reduced to 1-dimension to promote the practical application of the method. Thermo-physical properties such as the volumetric heat capacity tabulated in the calculation are introduced as a function of solidifying phases. Experimental equipment...
Dynamic stepping information process method in mobile bio-sensing computing environments.
Lee, Tae-Gyu; Lee, Seong-Hoon
2014-01-01
Recently, the interest toward human longevity free from diseases is being converged as one system frame along with the development of mobile computing environment, diversification of remote medical system and aging society. Such converged system enables implementation of a bioinformatics system created as various supplementary information services by sensing and gathering health conditions and various bio-information of mobile users to set up medical information. The existing bio-information system performs static and identical process without changes after the bio-information process defined at the initial system configuration executes the system. However, such static process indicates ineffective execution in the application of mobile bio-information system performing mobile computing. Especially, an inconvenient duty of having to perform initialization of new definition and execution is accompanied during the process configuration of bio-information system and change of method. This study proposes a dynamic process design and execution method to overcome such ineffective process.
Isolation of RNA from tumor samples: single-step guanidinium acid-phenol method.
Robertson, Naomi; Leek, Russell
2006-01-01
The guanidinium acid-phenol method of RNA extraction is relatively fast (4 h) and is useful for the processing of large numbers of samples, without the need for ultracentrifugation. This protocol produces total RNA that includes ribosomal, transfer, and messenger RNA. This high-quality RNA is suitable for Northern blot analysis, dot-blot hybridization, poly (A) RNA selection, in vitro translation, cDNA library construction, reverse transcriptase-polymerase chain reaction, ribonuclease protection assay, and primer extension experiments.
Directory of Open Access Journals (Sweden)
McGrail Matthew R
2012-11-01
Full Text Available Abstract Background The two step floating catchment area (2SFCA method has emerged in the last decade as a key measure of spatial accessibility, particularly in its application to primary health care access. Many recent ‘improvements’ to the original 2SFCA method have been developed, which generally either account for distance-decay within a catchment or enable the usage of variable catchment sizes. This paper evaluates the effectiveness of various proposed methods within these two improvement groups. Moreover, its assessment focuses on how well these improvements operate within and between rural and metropolitan populations over large geographical regions. Results Demonstrating these improvements to the whole state of Victoria, Australia, this paper presents the first comparison between continuous and zonal (step decay functions and specifically their effect within both rural and metropolitan populations. Especially in metropolitan populations, the application of either type of distance-decay function is shown to be problematic by itself. Its inclusion necessitates the addition of a variable catchment size function which can enable the 2SFCA method to dynamically define more appropriate catchments which align with actual health service supply and utilisation. Conclusion This study assesses recent ‘improvements’ to the 2SFCA when applied over large geographic regions of both large and small populations. Its findings demonstrate the necessary combination of both a distance-decay function and variable catchment size function in order for the 2SFCA to appropriately measure healthcare access across all geographical regions.
Dispersion of Co/CNTs via strong electrostatic adsorption method: Thermal treatment effect
Energy Technology Data Exchange (ETDEWEB)
Akbarzadeh, Omid, E-mail: omid.akbarzadeh63@gmail.com; Abdullah, Bawadi, E-mail: bawadi-abdullah@petronas.com.my; Subbarao, Duvvuri, E-mail: duvvuri-subbarao@petronas.com.my [Department of Chemical Engineering, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia); Zabidi, Noor Asmawati Mohd, E-mail: noorasmawati-mzabidi@petronas.com.my [Department of Fundamental and Applied Sciences, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia)
2015-07-22
The effect of different thermal treatment temperature on the structure of multi-walled carbon nanotubes (MWCNTs) and Co particle dispersion on CNTs support is studied using Strong electrostatic adsorption (SEA) method. The samples tested by N{sub 2}-adsorption, field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). N{sub 2}-adsorption results showed BET surface area increased using thermal treatment and TEM images showed that increasing the thermal treatment temperature lead to flaky CNTs and defects introduced on the outer surface and Co particle dispersion increased.
DEFF Research Database (Denmark)
Jakobsen, Bo; Sanz, Alejandro; Niss, Kristine
2016-01-01
and their crystallization, e.g., for locating the glass transition and melting point(s), as well as for investigating the stability against crystallization and estimating the relative change in specific heat between the solid and liquid phases at the glass transition......We present a simple method for fast and cheap thermal analysis on supercooled glass-forming liquids. This “Thermalization Calorimetry” technique is based on monitoring the temperature and its rate of change during heating or cooling of a sample for which the thermal power input comes from heat...
Evaluation of polarization of embedded piezoelectrics by the thermal wave method.
Suchaneck, Gunnar; Eydam, Agnes; Hu, Wenguo; Kranz, Burkhart; Drossel, Welf-Guntram; Gerlach, Gerald
2012-09-01
This work demonstrates the benefit of the thermal wave method for the evaluation of the polarization state of embedded piezoelectrics. Two types of samples were investigated: A low-temperature co-fired ceramics (LTCC)/lead zirconate titanate (PZT) sensor-actuator and a macro-fiber composite (MFC) actuator. At modulation frequencies below 10 Hz, the pyroelectric response was governed by thermal losses to the embedding layers. Here, the sample behavior was described by a harmonically heated piezoelectric plate exhibiting heat losses to the environment characterized by a single thermal relaxation time.
A method for statistical steady state thermal analysis of reactor cores
International Nuclear Information System (INIS)
Whetton, P.A.
1981-01-01
In a previous publication the author presented a method for undertaking statistical steady state thermal analyses of reactor cores. The present paper extends the technique to an assessment of confidence limits for the resulting probability functions which define the probability that a given thermal response value will be exceeded in a reactor core. Establishing such confidence limits is considered an integral part of any statistical thermal analysis and essential if such analysis are to be considered in any regulatory process. In certain applications the use of a best estimate probability function may be justifiable but it is recognised that a demonstrably conservative probability function is required for any regulatory considerations. (orig.)
DEFF Research Database (Denmark)
Swierczynski, Maciej Jozef; Stroe, Daniel Loan; Stanciu, Tiberiu
2017-01-01
, thermal modelling of lithium-ion battery cells and battery packs is gaining importance. Equivalent thermal circuits' models have proven to be relatively accurate with a low computational burden for the price of low spatial resolution; nevertheless, they usually require expensive equipment...... for thermal characterization of batteries. The scientific intention of this paper is to collect and systematize the state of knowledge about electrothermal impedance spectroscopy and present different measurement methods on the example of a high-power lithium battery cell and finally to discuss the prospect....
Low temperature thermal diffusivity of LiKSO4 obtained using the photoacoustic phase lag method
Directory of Open Access Journals (Sweden)
Jorge M.P.P.M.
1999-01-01
Full Text Available This paper describes the determination of the thermal diffusivity of LiKSO4 crystals using the photoacoustic phase lag method, in the 77 K to 300 K temperature interval. This method is quite simple and fast and when it is coupled to a specially designed apparatus, that includes a resonant photoacoustic cell, allows for the determination of the thermal diffusivity at low temperatures. The thermal diffusivity is an important parameter that depends on the temperature, and no values of this parameter for LiKSO4, at low temperature, have yet been reported. The LiKSO4 is a crystal with many phase transitions which can be detected via the anomalies in the variation of the thermal diffusivity as a function of the temperature.
DEFF Research Database (Denmark)
Weitzmann, Peter; Svendsen, Svend
2005-01-01
Lightweight floor heating systems consist of a plastic tube connected to a heat distribution aluminium plate and are used in wooden floor constructions. The thermal properties of lightweight floor heating systems cannot be described accurately. The reason is a very complex interaction of convection......, radiation and conduction of the heat transfer between pipe and surrounding materials. The European Standard for floor heating, EN1264, does not cover lightweight systems, while the supplemental Nordtest Method VVS127 is aimed at lightweight systems. The thermal properties can be found using tabulated values...... or experiments. Neither includes dynamic properties. This article describes a method to find steady-state and dynamical thermal properties in an experimental setup based on finding a characteristic thermal resistance between pipe and heat transfer plate, which can be directly implemented in a numerical...
Thermal analysis methods for LMFBR wire wrapped bundles
International Nuclear Information System (INIS)
Todreas, N.E.
1976-11-01
A note is presented which was written to stimulate an awareness and discussion of the fundamental differences in the formulation of certain existing analysis codes for LMFBR wire wrap bundles. The contention of the note is that for those array types where data exists (one wire per pin, equal start angles), the ENERGY method results for coolant temperature under forced convection conditions provide benchmarks of reliability equal to the results of codes COBRA and TH1-3D
Measurement of thermal neutrons density by the cadmium filter method
International Nuclear Information System (INIS)
Manent, G.
1967-01-01
The cadmium correction factor is defined and measured by the Tittle method for the gold. The author shows that this factor is constant in function of the detector thickness and that the resonant part of the cross section is preponderant for its determination. This property is needful to the cadmium correction factor calculation if, as usual, the effective cut energy variation of the filter is not taken into account with the detector thickness and the cadmium thickness. (A.L.B.) [fr
A three-step calibration method for tri-axial field sensors in a 3D magnetic digital compass
International Nuclear Information System (INIS)
Zhu, Xiaoning; Zhao, Ta; Zhou, Zhijian; Cheng, Defu
2017-01-01
In a 3D magnetic compass, it is important to calibrate the tri-axial magnetometers and accelerometers so the compass will provide accurate heading and attitude information. Previous researchers have used two methods to calibrate these two field sensors separately, i.e. the classic independent ellipsoid fitting method and the independent dot product invariant method, respectively. Both methods are easy to use, and no highly accurate, external equipment is required. However, self-calibration with ellipsoid fitting has the disadvantage that it interfuses an orthogonal matrix, and the dot product invariant method requires the use of pre-calibrated internal field sensors, which may be unavailable in many cases. In this paper, we have introduced and unified an error model of two tri-axial field sensors. Accordingly, the orthogonal matrix caused by ellipsoid fitting was mathematically proved to be the combination of two sources, the mounting misalignment and the rotation misalignment. Moreover, a new method, which we call optimal resultant vector, was proposed to further calibrate multi-sensor systems on the basis of ellipsoid fitting and dot product invariant methods, establishing a new, three-step calibration method. The superiority of the proposed method over the state-of-the-art approaches were demonstrated by simulations and a 3D compass experiment. (paper)
A three-step calibration method for tri-axial field sensors in a 3D magnetic digital compass
Zhu, Xiaoning; Zhao, Ta; Cheng, Defu; Zhou, Zhijian
2017-04-01
In a 3D magnetic compass, it is important to calibrate the tri-axial magnetometers and accelerometers so the compass will provide accurate heading and attitude information. Previous researchers have used two methods to calibrate these two field sensors separately, i.e. the classic independent ellipsoid fitting method and the independent dot product invariant method, respectively. Both methods are easy to use, and no highly accurate, external equipment is required. However, self-calibration with ellipsoid fitting has the disadvantage that it interfuses an orthogonal matrix, and the dot product invariant method requires the use of pre-calibrated internal field sensors, which may be unavailable in many cases. In this paper, we have introduced and unified an error model of two tri-axial field sensors. Accordingly, the orthogonal matrix caused by ellipsoid fitting was mathematically proved to be the combination of two sources, the mounting misalignment and the rotation misalignment. Moreover, a new method, which we call optimal resultant vector, was proposed to further calibrate multi-sensor systems on the basis of ellipsoid fitting and dot product invariant methods, establishing a new, three-step calibration method. The superiority of the proposed method over the state-of-the-art approaches were demonstrated by simulations and a 3D compass experiment.
Determination of optimum thermal debinding and sintering process parameters using Taguchi Method
CSIR Research Space (South Africa)
Seerane, M
2015-07-01
Full Text Available on the basis of obtaining a defect-free part after sintering and also determining a sintering time that gives high sintering density. Thermal debinding was conducted after solvent debinding. The feedstock used to produce green compacts composed of Ti6Al4V... International Light Metals Technology Conference (LMT 2015), Port Elizabeth, South Africa, July 27-29 Determination of Optimum Process for Thermal Debinding and Sintering using Taguchi Method SEERANE Mandya,*, CHIKWANDA Hildab, MACHAKA Ronaldc CSIR...
Evaluation of Methods for Calculating Soil Thermal Conductivity,
1982-03-01
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Extension of the thermal porosimetry method to high gas pressure for nanoporosimetry estimation
Jannot, Y.; Degiovanni, A.; Camus, M.
2018-04-01
Standard pore size determination methods like mercury porosimetry, nitrogen sorption, microscopy, or X-ray tomography are not suited to highly porous, low density, and thus very fragile materials. For this kind of materials, a method based on thermal characterization has been developed in a previous study. This method has been used with air pressure varying from 10-1 to 105 Pa for materials having a thermal conductivity less than 0.05 W m-1 K-1 at atmospheric pressure. It enables the estimation of pore size distribution between 100 nm and 1 mm. In this paper, we present a new experimental device enabling thermal conductivity measurement under gas pressure up to 106 Pa, enabling the estimation of the volume fraction of pores having a 10 nm diameter. It is also demonstrated that the main thermal conductivity models (parallel, series, Maxwell, Bruggeman, self-consistent) lead to the same estimation of the pore size distribution as the extended parallel model (EPM) presented in this paper and then used to process the experimental data. Three materials with thermal conductivities at atmospheric pressure ranging from 0.014 W m-1 K-1 to 0.04 W m-1 K-1 are studied. The thermal conductivity measurement results obtained with the three materials are presented, and the corresponding pore size distributions between 10 nm and 1 mm are presented and discussed.
Flight Validation of the Thermal Propellant Gauging Method used at EADS Astrium
Dandaleix, L.; Ounougha, L.; Jallade, S.
2004-10-01
EADS Astrium recently met a major milestone in the field of propellant gauging with the first reorbitation of an Eurostar tanks equipped satellite. It proved successful determining the remaining available propellant mass for spacecraft displacement beyond the customer specified graveyard orbit; thus demonstrating its expertness in Propellant Gauging in correlation with tank residual mass minimization. A critical parameter in satellite operational planning is indeed the accurate knowledge of the on-board remaining propellant mass; basically for the commercial telecommunication missions, where it is the major criterion for lifetime maximization. To provide an accurate and reliable process for measurement of this propellant mass throughout lifetime, EADS Astrium uses a Combination of two independent techniques: The Dead Reckoning Method (maximum accuracy at BOL), based on thrusters flow rate prediction &the Thermal Propellant Gauging Technique, deriving the propellant mass from the tank thermal capacity (Absolute gauging method, with increasing accuracy along lifetime). Then, the present article shows the recent flight validation of the Gauging method obtained for Eurostar E2000 propellant tanks including the validation of the different thermodynamic models. ABBREVIATIONS &ACRONYMS BOL, MOL, EOL: Beginning, Middle &End of Life Cempty: Empty tank thermal inertia [J/K] Chelium: Helium thermal inertia [J/K] Cpropellant: Propellant thermal inertia [J/K] Ct = C1+C2: Total tank thermal inertia (Subscript for upper node and for lower node) [J/K] CPS: Combined Propulsion System DR: Dead Reckoning FM: Flight Model LAE: Liquid Apogee Engine lsb: Least significant byte M0: TPGS Uncertainty component linked to Cempty mox, mfuel: Propellant mass of oxidiser &fuel [kg] Pox, Pfuel: Pressure of oxidiser &fuel [bar] PTA: Propellant Tank Assembly Q: Heater power [W] Qox, Qfuel: Mass flow rate of oxidiser &fuel [kg/s] RCT: Reaction Control Thrusters T0: Spacecraft platform equilibrium
Azin, Anton; Zhukov, Andrey A.; Ponomarev, Sergey A.; Ponomarev, Sergey V.
2017-11-01
In designing sophisticated printed circuit boards, required evaluation of the product life cycle is relevant in terms of presumably applied load conditions during operation. The paper describes the durability evaluation method of printed circuit board components with contact output such as ball grid array (BGA) and pitch grid array (PGA) under thermal loads. Experiment data and numerical simulation results of soldered connections have been obtained. This method is demonstrated by a practical application example-evaluating of printed circuit board durability under cyclic thermal loads. The application of proposed method for printed circuit boards would make it possible to predict the service life of these designed products.
Directory of Open Access Journals (Sweden)
S.N. Nnamchi
2010-01-01
Full Text Available Determination of the thermal conductivity and the specific heat capacity of neem seeds (Azadirachta indica A. Juss usingthe inverse method is the main subject of this work. One-dimensional formulation of heat conduction problem in a spherewas used. Finite difference method was adopted for the solution of the heat conduction problem. The thermal conductivityand the specific heat capacity were determined by least square method in conjunction with Levenberg-Marquardt algorithm.The results obtained compare favourably with those obtained experimentally. These results are useful in the analysis ofneem seeds drying and leaching processes.
International Nuclear Information System (INIS)
Wu, Bin; Ye, Shenghua; Xue, Ting
2010-01-01
A novel two-step method for spatial circle orientation with a structured light vision sensor is proposed for a 3D flexible visual inspection system guided by an industrial robot. Firstly the z coordinate of a spatial circle center is estimated, secondly the x and y coordinates are estimated with the center orientation relative to the camera optic center, and then its radius is computed. Simultaneously, the x, y and z coordinate orientation errors are analyzed in detail. It shows that the method is feasible and valid, and the orientation accuracy for the spatial circle exceeds 0.15 mm by experiment. It eliminates the bottleneck of the traditional orientation method with a stereovision sensor, and greatly expands the application of the structured light visual inspection system
International Nuclear Information System (INIS)
Khan, S.H.; Ivanov, A.A.
1995-01-01
An analytical method for calculating static characteristics of linear dc step motors (LSM) is described. These multiphase passive-armature motors are now being developed for control rod drives (CRD) in large nuclear reactors. The static characteristics of such LSM is defined by the variation of electromagnetic force with armature displacement and it determines motor performance in its standing and dynamic modes of operation. The proposed analytical technique for calculating this characteristic is based on the permeance analysis method applied to phase magnetic circuits of LSM. Reluctances of various parts of phase magnetic circuit is calculated analytically by assuming probable flux paths and by taking into account complex nature of magnetic field distribution in it. For given armature positions stator and armature iron saturations are taken into account by an efficient iterative algorithm which gives fast convergence. The method is validated by comparing theoretical results with experimental ones which shows satisfactory agreement for small stator currents and weak iron saturation
Fransen, Koos; Neutens, Tijs; De Maeyer, Philippe; Deruyter, Greet
2015-03-01
This paper puts forward a commuter-based version of the two-step floating catchment area (2SFCA) method, which has gained acceptance in studies on spatial health care accessibility. Current implementations of the 2SFCA method are static in that they consider centroid-based night-time representations of the population. The proposed enhancement to the 2SFCA approach addresses this limitation by accounting for trip-chaining behavior. The presented method is illustrated in a case study of accessibility of daycare centers in the province East Flanders in Belgium. The results show significant spatial differences in accessibility between the original and commuter-based version of the 2SFCA (CB2SFCA). They highlight the importance of giving heed to more complex travel behavior in cases where the need for detailed accessibility calculations is apparent. Copyright © 2015 Elsevier Ltd. All rights reserved.
KrishnaKumar, V Guru; Gupta, Sharad
2017-05-28
Tau is an intrinsically disordered protein responsible for maintaining the structure and stability of axonal microtubules. However, in certain disease conditions including Alzheimer's disease, tau protein may undergo biochemical and structural changes to form intracellular aggregates. Since tau is a proline- and arginine-rich eukaryotic protein, heterologous expression in Escherichia coli often results in poor yield and has been a major technical challenge. In the current work, we have improved the expressed yield of tau by overcoming codon bias problem and established a simplified protocol for efficient extraction. The reported method has two distinct features: (i) enhanced tau expression (upto eightfold) by supplementing deficient tRNAs that aid in rapid translation and (ii) direct boiling of expressed E. coli cells to extract tau with no separate cell lysis step. We further demonstrate that tau extracted by the direct boiling method is similar to tau purified by size-exclusion chromatography exhibiting similar structural and biophysical characteristics including aggregation propensity. Since morphologies and in vitro toxicity of fibrillar tau aggregates were also similar, tau extracted by the one-step direct boiling method can be used for tau aggregation assays without any additional purification.
Munoz, E. F.; Silverman, M. P.
1979-01-01
A single-step most-probable-number method for determining the number of fecal coliform bacteria present in sewage treatment plant effluents is discussed. A single growth medium based on that of Reasoner et al. (1976) and consisting of 5.0 gr. proteose peptone, 3.0 gr. yeast extract, 10.0 gr. lactose, 7.5 gr. NaCl, 0.2 gr. sodium lauryl sulfate, and 0.1 gr. sodium desoxycholate per liter is used. The pH is adjusted to 6.5, and samples are incubated at 44.5 deg C. Bacterial growth is detected either by measuring the increase with time in the electrical impedance ratio between the innoculated sample vial and an uninnoculated reference vial or by visual examination for turbidity. Results obtained by the single-step method for chlorinated and unchlorinated effluent samples are in excellent agreement with those obtained by the standard method. It is suggested that in automated treatment plants impedance ratio data could be automatically matched by computer programs with the appropriate dilution factors and most probable number tables already in the computer memory, with the corresponding result displayed as fecal coliforms per 100 ml of effluent.
International Nuclear Information System (INIS)
Ma, Fujun; Peng, Changsheng; Hou, Deyi; Wu, Bin; Zhang, Qian; Li, Fasheng; Gu, Qingbao
2015-01-01
Highlights: • Hg content was reduced to <1.5 mg/kg when treated at 400 °C with citric acid. • The treated soil retained most of its original soil physicochemical properties. • Proton provided by citric acid facilitates thermal removal of mercury. • This thermal treatment method is expected to reduce energy input by 35%. - Abstract: Thermal treatment is a promising technology for the remediation of mercury contaminated soils, but it often requires high energy input at heating temperatures above 600 °C, and the treated soil is not suitable for agricultural reuse. The present study developed a novel method for the thermal treatment of mercury contaminated soils with the facilitation of citric acid (CA). A CA/Hg molar ratio of 15 was adopted as the optimum dosage. The mercury concentration in soils was successfully reduced from 134 mg/kg to 1.1 mg/kg when treated at 400 °C for 60 min and the treated soil retained most of its original soil physiochemical properties. During the treatment process, CA was found to provide an acidic environment which enhanced the volatilization of mercury. This method is expected to reduce energy input by 35% comparing to the traditional thermal treatment method, and lead to agricultural soil reuse, thus providing a greener and more sustainable remediation method for treating mercury contaminated soil in future engineering applications.
Energy Technology Data Exchange (ETDEWEB)
Ma, Fujun [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Peng, Changsheng [The Key Lab of Marine Environmental Science and Ecology, Ministry of Education, Ocean University of China, Qingdao 266100 (China); Hou, Deyi [Geotechnical and Environmental Research Group, Department of Engineering, University of Cambridge, Cambridge CB2 1PZ (United Kingdom); Wu, Bin; Zhang, Qian; Li, Fasheng [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Gu, Qingbao, E-mail: guqb@craes.org.cn [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China)
2015-12-30
Highlights: • Hg content was reduced to <1.5 mg/kg when treated at 400 °C with citric acid. • The treated soil retained most of its original soil physicochemical properties. • Proton provided by citric acid facilitates thermal removal of mercury. • This thermal treatment method is expected to reduce energy input by 35%. - Abstract: Thermal treatment is a promising technology for the remediation of mercury contaminated soils, but it often requires high energy input at heating temperatures above 600 °C, and the treated soil is not suitable for agricultural reuse. The present study developed a novel method for the thermal treatment of mercury contaminated soils with the facilitation of citric acid (CA). A CA/Hg molar ratio of 15 was adopted as the optimum dosage. The mercury concentration in soils was successfully reduced from 134 mg/kg to 1.1 mg/kg when treated at 400 °C for 60 min and the treated soil retained most of its original soil physiochemical properties. During the treatment process, CA was found to provide an acidic environment which enhanced the volatilization of mercury. This method is expected to reduce energy input by 35% comparing to the traditional thermal treatment method, and lead to agricultural soil reuse, thus providing a greener and more sustainable remediation method for treating mercury contaminated soil in future engineering applications.
Standard Test Method for Thermal Oxidative Resistance of Carbon Fibers
American Society for Testing and Materials. Philadelphia
1982-01-01
1.1 This test method covers the apparatus and procedure for the determination of the weight loss of carbon fibers, exposed to ambient hot air, as a means of characterizing their oxidative resistance. 1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to inch-pound units which are provided for information only and are not considered standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard information, see Section 8.
A Two-Step Segmentation Method for Breast Ultrasound Masses Based on Multi-resolution Analysis.
Rodrigues, Rafael; Braz, Rui; Pereira, Manuela; Moutinho, José; Pinheiro, Antonio M G
2015-06-01
Breast ultrasound images have several attractive properties that make them an interesting tool in breast cancer detection. However, their intrinsic high noise rate and low contrast turn mass detection and segmentation into a challenging task. In this article, a fully automated two-stage breast mass segmentation approach is proposed. In the initial stage, ultrasound images are segmented using support vector machine or discriminant analysis pixel classification with a multiresolution pixel descriptor. The features are extracted using non-linear diffusion, bandpass filtering and scale-variant mean curvature measures. A set of heuristic rules complement the initial segmentation stage, selecting the region of interest in a fully automated manner. In the second segmentation stage, refined segmentation of the area retrieved in the first stage is attempted, using two different techniques. The AdaBoost algorithm uses a descriptor based on scale-variant curvature measures and non-linear diffusion of the original image at lower scales, to improve the spatial accuracy of the ROI. Active contours use the segmentation results from the first stage as initial contours. Results for both proposed segmentation paths were promising, with normalized Dice similarity coefficients of 0.824 for AdaBoost and 0.813 for active contours. Recall rates were 79.6% for AdaBoost and 77.8% for active contours, whereas the precision rate was 89.3% for both methods. Copyright © 2015 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.
In situ performance and potential applications of a thermal bed-load measurement method
CSIR Research Space (South Africa)
Ilgner, HJ
2010-09-01
Full Text Available Methods to detect the flow condition at the pipeline invert are reviewed. New results of a small heated plate inserted into a non-metallic pipe are presented. This thermal method is based on mini-heaters and can detect erratic flow behaviour near...
DEFF Research Database (Denmark)
Haller, Michel; Cruickshank, Chynthia; Streicher, Wolfgang
2009-01-01
This paper reviews different methods that have been proposed to characterize thermal stratification in energy storages from a theoretical point of view. Specifically, this paper focuses on the methods that can be used to determine the ability of a storage to promote and maintain stratification...
Food demand in Brazil: an application of Shonkwiler & Yen Two-Step estimation method
Directory of Open Access Journals (Sweden)
Alexandre Bragança Coelho
2010-03-01
Full Text Available The objective of the analysis is to estimate a demand system including eighteen food products using data from a Brazilian Household Budget Survey carried out in 2002 and 2003 (POF 2002/2003. The functional form used was Quadratic Almost Ideal Demand System (QUAIDS. Estimation employs the Shonkwiler and Yen method to account for zero consumption. Results showed that purchase probabilities of staples foods were negatively related to family monthly income, while meat, milk and other products showed a positive relation. Regional, educational and urbanization variables were also important in the first stage estimation. While some of the goods had negative income coefficients, none were inferior and six of eighteen were luxuries based on second stage estimates.O objetivo deste artigo é analisar a demanda de alimentos no Brasil por meio da estimação de um sistema de demanda com dezoito produtos usando dados da Pesquisa de Orçamentos Familiares realizada em 2002 e 2003 (POF 2002/2003. A forma funcional utilizada foi o Quadratic Almost Ideal Demand System (QUAIDS. A estimação utiliza o Procedimento de Shonkwiler e Yen para lidar com o problema do consumo zero. Os resultados mostraram que as probabilidades de aquisição dos produtos básicos foram negativamente relacionadas com a renda familiar mensal, enquanto carnes, leite e outros produtos mostraram uma relação positiva. As variáveis de educação, regionais e de localização do domicílio também foram importantes no primeiro estágio da estimação. Em relação às elasticidades-renda, nenhum bem foi considerado inferior e seis de dezoito foram considerados bens de luxo.
Non thermal plasma surface cleaner and method of use
Neophytou, Marios
2017-09-14
Described herein are plasma generation devices and methods of use of the devices. The devices can be used for the cleaning of various surfaces and/or for inhibiting or preventing the accumulation of particulates, such as dust, or moisture on various surfaces. The devices can be used to remove dust and other particulate contaminants from solar panels and windows, or to avoid or minimize condensation on various surfaces. In an embodiment a plasma generation device is provided. The plasma generation device can comprise: a pair of electrodes (1,2) positioned in association with a surface of a dielectric substrate (3). The pair of electrodes (1,2) can comprise a first electrode (1) and a second electrode (2). The first electrode and second electrode can be of different sizes, one of the electrodes being smaller than the other of the electrodes. The first electrode and second electrode can be separated by a distance and electrically connected to a voltage source (4,5).
Li, Chao-Feng; Li, Xian-Hua; Li, Qiu-Li; Guo, Jing-Hui; Li, Xiang-Hui; Yang, Yue-Heng
2012-05-21
Thermal ionization mass spectrometry (TIMS) offers the excellent precision and accuracy of the Sr and Nd isotopic ratio analysis for geological samples, but this method is labour intensive, expensive and time-consuming. In this study, a new analytical protocol by TIMS is presented that aims at improving analytical efficiency and cutting down experimental cost. Using the single-step cation exchange resin technique, mixed Sr and rare earth elements (REEs) fractions were separated from matrix and evaporated to dryness. Afterwards, mixed Sr+REEs fractions were dissolved and loaded onto the same Re filament using 1 μL of 2 M HCl. Then, Sr and Nd were sequentially measured without venting using TIMS. In contrast to conventional TIMS methods, the merits of this analytical protocol are its cost- and time-saving adaptations. The applicability of our method is evaluated by replicated measurements of (87)Sr/(86)Sr and (143)Nd/(144)Nd for nine international silicate rock reference materials, spanning a wide range of bulk compositions. The typical internal precision in this study is ca. 0.001% (RSE) for (87)Sr/(86)Sr and (143)Nd/(144)Nd; the analytical results obtained for these standard rocks show a good agreement with reported values, indicating the effectiveness of the proposed method. Copyright © 2012 Elsevier B.V. All rights reserved.
International Nuclear Information System (INIS)
Gupta, A.; Hong, S.; Moacanin, J.
1981-01-01
A method and apparatus for measuring thermal diffusivity and molecular relaxation processes in a sample material utilizing two light beams, one being a pulsed laser light beam for forming a thermal lens in the sample material, and the other being a relatively low power probe light beam for measuring changes in the refractive index of the sample material during formation and dissipation of the thermal lens. More specifically, a sample material is irradiated by relatively high power, short pulses from a dye laser. Energy from the pulses is absorbed by the sample material, thereby forming a thermal lens in the area of absorption. The pulse repetition rate is chosen so that the thermal lens is substantially dissipated by the time the next pulse reaches the sample material. A probe light beam, which in a specific embodiment is a relatively low power, continuous wave (Cw) laser beam, irradiates the thermal lens formed in the sample material. The intensity characteristics of the probe light beam subsequent to irradiation of the thermal lens is related to changes in the refractive index of the sample material as the thermal lens is formed and dissipated. A plot of the changes in refractive index as a function of time during formation of the thermal lens as reflected by changes in intensity of the probe beam, provides a curve related to molecular relaxation characteristics of the material, and a plot during dissipation of the thermal lens provides a curve related to the thermal diffusivity of the sample material
Morikawa, Junko; Zamengo, Massimiliano; Kato, Yukitaka
2016-05-01
The global interest in energy applications activates the advanced study about the molten salts in the usage of fluids in the power cycle, such as for transport and heat storage in solar power facilities. However, the basic properties of molten salts show a general scattering in characterization especially in thermal properties. It is suggested that new studies are required on the measurement of thermal properties of solar salts using recent technologies. In this study, micro-scale heat transfer and phase change in molten salts are presented using our originally developed device: the micro-bolometer Infrared focal plane arrays (IR FPA) measuring system is a portable type instrument, which is re-designed to measure the thermal phenomena in high temperature up to 700 °C or higher. The superimpose system is newly setup adjusted to the signal processing in high temperature to realize the quantitative thermal imaging, simultaneously. The portable type apparatus for a quantitative micro-scale thermography using a micro-bolometer has been proposed based on an achromatic lens design to capture a micro-scale image in the long-wave infrared, a video signal superimposing for the real time emissivity correction, and a pseudo acceleration of a timeframe. Combined with the superimpose technique, the micro-scale thermal imaging in high temperature is achieved and the molten flows of the solar salts, sodium nitrate, and potassium nitrate are successfully observed. The solar salt, the mixture of sodium nitrate and potassium nitrate, shows a different shape of exothermic heat front morphology in the lower phase transition (solidification) temperature than the nitrates on cooling. The proposed measuring technique will be utilized to accelerate the screening step to determine the phase diagram and the eutectics of the multiple mixtures of candidate molten salts, which may be used as heat transport medium from the concentrated solar power to a processing plant for thermal energy
Directory of Open Access Journals (Sweden)
Tony Hak
2008-12-01
Full Text Available Three-Step Test-Interview (TSTI is a method for pretesting a self-completion questionnaire by first observing actual instances of interaction between the instrument and respondents (the response process before exploring the reasons for this behavior. The TSTI consists of the following three steps: 1. (Respondent-driven observation of response behavior. 2. (Interviewer-driven follow-up probing aimed at remedying gaps in observational data. 3. (Interviewer-driven debriefing aimed at eliciting experiences and opinions. We describe the aims and the techniques of these three steps, and then discuss pilot studies in which we tested the feasibility and the productivity of the TSTI by applying it in testing three rather different types of questionnaires. In the first study, the quality of a set of questions about alcohol consumption was assessed. The TSTI proved to be productive in identifying problems that resulted from a mismatch between the ‘theory’ underlying the questions on the one hand, and features of a respondent’s actual behavior and biography on the other hand. In the second pilot study, Dutch and Norwegian versions of an attitude scale, the 20-item Illegal Aliens Scale, were tested. The TSTI appeared to be productive in identifying problems that resulted from different ‘response strategies’. In the third pilot, a two-year longitudinal study, the TSTI appeared to be an effective method for documenting processes of ‘response shift’ in repeated measurements of health-related Quality of Life (QoL.
Sensitivity Analysis of the Thermal Response of 9975 Packaging Using Factorial Design Methods
International Nuclear Information System (INIS)
Gupta, Narendra K.
2005-01-01
A method is presented for using the statistical design of experiment (2 k Factorial Design) technique in the sensitivity analysis of the thermal response (temperature) of the 9975 radioactive material packaging where multiple thermal properties of the impact absorbing and fire insulating material Celotex and certain boundary conditions are subject to uncertainty. 2 k Factorial Design method is very efficient in the use of available data and is capable of analyzing the impact of main variables (Factors) and their interactions on the component design. The 9975 design is based on detailed finite element (FE) analyses and extensive proof testing to meet the design requirements given in 10CFR71 [1]. However, the FE analyses use Celotex thermal properties that are based on published data and limited experiments. Celotex is an orthotropic material that is used in the home building industry. Its thermal properties are prone to variation due to manufacturing and fabrication processes, and due to long environmental exposure. This paper will evaluate the sensitivity of variations in thermal conductivity of the Celotex, convection coefficient at the drum surface, and drum emissivity (herein called Factors) on the thermal response of 9975 packaging under Normal Conditions of Transport (NCT). Application of this methodology will ascertain the robustness of the 9975 design and it can lead to more specific and useful understanding of the effects of various Factors on 9975 performance
Simplified Method for the Characterization of Rectangular Straw Bales (RSB) Thermal Conductivity
Conti, Leonardo; Goli, Giacomo; Monti, Massimo; Pellegrini, Paolo; Rossi, Giuseppe; Barbari, Matteo
2017-10-01
This research aims to design and implement tools and methods focused at the assessment of the thermal properties of full size Rectangular Straw Bales (RSB) of various nature and origin, because their thermal behaviour is one of the key topics in market development of sustainable building materials. As a first approach a method based on a Hot-Box in agreement with the ASTM C1363 - 11 standard was adopted. This method was found to be difficult for the accurate measurement of energy flows. Instead, a method based on a constant energy input was developed. With this approach the thermal conductivity of a Rectangular Straw-Bale (RSB λ) can be determined by knowing the thermal conductivity of the materials used to build the chamber and the internal and external temperature of the samples and of the chamber. A measurement a metering chamber was built and placed inside a climate chamber, maintained at constant temperature. A known quantity of energy was introduced inside the metering chamber. A series of thermopiles detects the temperature of the internal and external surfaces of the metering chamber and of the specimens allowing to calculate the thermal conductivity of RSB in its natural shape. Different cereal samples were tested. The values were found consistent with those published in scientific literature.
Improved staining method for determining the extent of thermal damage to cells.
Sherwood, Margaret E; Flotte, Thomas J
2007-02-01
Enzyme histochemical stains of frozen sections have been used by investigators to assess thermal damage. The assessment of thermal damage to cells in lipid-rich tissues such as subcutaneous tissue and sebaceous glands can be difficult due to the quality of frozen sections of such tissues. The purpose of this study is to develop an improved method for this type of evaluation. Thick frozen sections of thermally damaged pig and human skin were stained for lactate dehydrogenase. The sections were fixed in formalin and processed for paraffin-embedded sections. The sections showed well-defined localization of the enzymatic deposits as well as preservation of the tissue architecture. The paraffin-embedded lactate dehydrogenase stained sections provide improved evaluation of thermally damaged tissues, particularly the lipid rich tissues. (c) 2007 Wiley-Liss, Inc.
Advanced Thermal Energy Conversion of Temperature under 300°C by Thermoelectric Conversion Method
Ueda, Tadashi; Uchida, Yoshiyuki; Shingu, Hiroyasu
Many approaches have been developing for energy conversion throughout the world. However, it is difficult to achieve the global warming countermeasure based on “The Kyoto protocol”. Until now effective utilization of low temperature thermal energy (under 300°C) is not advancing one. For example, effective utilization method has not been established for waste heat energy which arise from industry machine tools, automobiles, internal combustion engines and thermal energy from natural environment, etc. In this paper, we reported the experiment for effective utilizing of low temperature (under 300°C) thermal energy conversion. The device used for the measurement is a copper thermo device. Thermo electromotive force of 150mW/cm2 was obtained at 200°C. The obtained thermo electromotive force is about 15 times higher in comparison with generally used alumal-chromal thermocouple. Our aim is that utilizes low temperature thermal energy effectively by converting into electricity.
Method and apparatus for obtaining enhanced production rate of thermal chemical reactions
Tonkovich, Anna Lee Y [Pasco, WA; Wang, Yong [Richland, WA; Wegeng, Robert S [Richland, WA; Gao, Yufei [Kennewick, WA
2003-04-01
The present invention is a method and apparatus (vessel) for providing a heat transfer rate from a reaction chamber through a wall to a heat transfer chamber substantially matching a local heat transfer rate of a catalytic thermal chemical reaction. The key to the invention is a thermal distance defined on a cross sectional plane through the vessel inclusive of a heat transfer chamber, reaction chamber and a wall between the chambers. The cross sectional plane is perpendicular to a bulk flow direction of the reactant stream, and the thermal distance is a distance between a coolest position and a hottest position on the cross sectional plane. The thermal distance is of a length wherein the heat transfer rate from the reaction chamber to the heat transfer chamber substantially matches the local heat transfer rate.
A steady-state high-temperature method for measuring thermal conductivity of refractory materials
Manzolaro, M.; Corradetti, S.; Andrighetto, A.; Ferrari, L.
2013-05-01
A new methodology and an instrumental setup for the thermal conductivity estimation of isotropic bulk graphite and different carbides at high temperatures are presented. The method proposed in this work is based on the direct measurement of temperature and emissivity on the top surface of a sample disc of known dimensions. Temperatures measured under steady-state thermal equilibrium are then used to estimate the thermal conductivity of the sample by making use of the inverse parameter estimation technique. Thermal conductivity values obtained in this way are then compared to the material data sheets and values found in literature. The reported work has been developed within the Research and Development framework of the SPES (Selective Production of Exotic Species) project at INFN-LNL (Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali di Legnaro).
Rizvi, Zarghaam Haider; Shrestha, Dinesh; Sattari, Amir S.; Wuttke, Frank
2018-02-01
Macroscopic parameters such as effective thermal conductivity (ETC) is an important parameter which is affected by micro and meso level behaviour of particulate materials, and has been extensively examined in the past decades. In this paper, a new lattice based numerical model is developed to predict the ETC of sand and modified high thermal backfill material for energy transportation used for underground power cables. 2D and 3D simulations are performed to analyse and detect differences resulting from model simplification. The thermal conductivity of the granular mixture is determined numerically considering the volume and the shape of the each constituting portion. The new numerical method is validated with transient needle measurements and the existing theoretical and semi empirical models for thermal conductivity prediction sand and the modified backfill material for dry condition. The numerical prediction and the measured values are in agreement to a large extent.
Intelligent screening of electrofusion-polyethylene joints based on a thermal NDT method
Doaei, Marjan; Tavallali, M. Sadegh
2018-05-01
The combinations of infrared thermal images and artificial intelligence methods have opened new avenues for pushing the boundaries of available testing methods. Hence, in the current study, a novel thermal non-destructive testing method for polyethylene electrofusion joints was combined with k-means clustering algorithms as an intelligent screening tool. The experiments focused on ovality of pipes in the coupler, as well as misalignment of pipes-couplers in 25 mm diameter joints. The temperature responses of each joint to an internal heat pulse were recorded by an IR thermal camera, and further processed to identify the faulty joints. The results represented clustering accuracy of 92%, as well as more than 90% abnormality detection capabilities.
A new simple method for analysing of thermal noise in switched-capacitor filters
Rashtian, Mohammad; Afshin Hemmatyar, Ali Mohammad; Hashemipour, Omid
2012-12-01
Thermal noise is one of the most important challenges in analogue integrated circuits design. This problem is more crucial in switched-capacitor (SC) filters due to the aliasing effect of wide-band thermal noise. In this article, a new simple method is proposed for estimating the power spectrum density of output thermal noise in SC filters, which have acceptable accuracy and short running time. In the proposed method, first using HSPICE simulator, accurate value of accumulated sampled noise on sampler capacitors in each clock state is achieved. Next, using difference equations of the SC filter, frequency response of the SC filter is shaped by time domain analysis. Based on the proposed method, a SC low-pass filter and a second-order SC band-pass filter are analysed. The results are validated by comparing to the previously measured data.
Thermal conductivity of cellular metals measured by the transient plane sour method
Energy Technology Data Exchange (ETDEWEB)
Solorzano, E.; Rodriguez-Perez, M.A.; Saja, J.A. de [Cellular Materials Group (CELLMAT), Condensed Matter Physics Department, Faculty of Sciences, University of Valladolid (Spain)
2008-04-15
The thermal conductivity of a collection of cellular metals has been measured by the Transient Plane Source (TPS) method. Using this method, it has been possible to cover different volumes of selected samples and to study their in-homogeneities from their surface to their inner part. Additionally, these samples have been characterized by tomography. The density of the different volumes covered by the heat flow has been calculated from the tomographic slices and it has been related to the thermal conductivity measurements. These results have shown a similar trend to those obtained characterizing the bulk samples. With the TPS method, in combination with tomography, it has been possible to analyse the in-homogeneity of the samples as well as to characterize the thermal conductivity of a single in-homogeneous sample as a complete collection of different porosity specimens. (Abstract Copyright [2008], Wiley Periodicals, Inc.)
Energy Technology Data Exchange (ETDEWEB)
Oh, Sun Ryung; Park, Hyun Sun [POSTECH, Pohang (Korea, Republic of); Kim, Moo Hwan [KAERI, Daejeon (Korea, Republic of)
2016-05-15
The sodium-cooled fast reactor (SFR) is one of generation IV type reactors and has been extensively researched since 1950s. A strong advantage of the SFR is its liquid sodium coolant which is well-known for its superior thermal properties. However, in terms of possible pipe leakage or rupture, a liquid sodium coolant possesses a critical issue due to its high chemical reactivity which leads to fire or explosion. Due to its safety concerns, dispersion of nanoparticles in liquid sodium has been proposed to reduce the chemical reactivity of sodium. In case of sodium based titanium nanofluid (NaTiNF), the chemical reactivity suppression effect when interacting with water has been proved both experimentally and theoretically [1,2]. Suppression of chemical reactivity is critical without much loss of high heat transfer characteristic of sodium. As there is no research conducted for applying 3-omega sensor in liquid metal as well as high temperature liquid, the sensor development is performed for using in NaTiNF as well as effective thermal conductivity model validation. Based on the acquired effective thermal conductivity of NaTiNF, existing effective thermal conductivity models are evaluated. Thermal conductivity measurement is performed for liquid sodium based titanium nanofluid (NaTiNF) through 3-Omega method. The experiment is conducted at three temperature points of 120, 150, and 180 .deg. C for both pure liquid sodium and NaTiNF. By using 3- omega sensor, thermal conductivity measurement of liquid metal can be more conveniently conducted in labscale. Also, its possibility to measure the thermal conductivity of high temperature liquid metal with metallic nanoparticles being dispersed is shown. Unlike other water or oil-based nanofluids, NaTiNF exhibits reduction of thermal conductivity compare with liquid sodium. Various nanofluid models are plotted, and it is concluded that the MSBM which considers interfacial resistance and Brownian motion can be used in predicting
International Nuclear Information System (INIS)
Oh, Sun Ryung; Park, Hyun Sun; Kim, Moo Hwan
2016-01-01
The sodium-cooled fast reactor (SFR) is one of generation IV type reactors and has been extensively researched since 1950s. A strong advantage of the SFR is its liquid sodium coolant which is well-known for its superior thermal properties. However, in terms of possible pipe leakage or rupture, a liquid sodium coolant possesses a critical issue due to its high chemical reactivity which leads to fire or explosion. Due to its safety concerns, dispersion of nanoparticles in liquid sodium has been proposed to reduce the chemical reactivity of sodium. In case of sodium based titanium nanofluid (NaTiNF), the chemical reactivity suppression effect when interacting with water has been proved both experimentally and theoretically [1,2]. Suppression of chemical reactivity is critical without much loss of high heat transfer characteristic of sodium. As there is no research conducted for applying 3-omega sensor in liquid metal as well as high temperature liquid, the sensor development is performed for using in NaTiNF as well as effective thermal conductivity model validation. Based on the acquired effective thermal conductivity of NaTiNF, existing effective thermal conductivity models are evaluated. Thermal conductivity measurement is performed for liquid sodium based titanium nanofluid (NaTiNF) through 3-Omega method. The experiment is conducted at three temperature points of 120, 150, and 180 .deg. C for both pure liquid sodium and NaTiNF. By using 3- omega sensor, thermal conductivity measurement of liquid metal can be more conveniently conducted in labscale. Also, its possibility to measure the thermal conductivity of high temperature liquid metal with metallic nanoparticles being dispersed is shown. Unlike other water or oil-based nanofluids, NaTiNF exhibits reduction of thermal conductivity compare with liquid sodium. Various nanofluid models are plotted, and it is concluded that the MSBM which considers interfacial resistance and Brownian motion can be used in predicting
First 3D thermal mapping of an active volcano using an advanced photogrammetric method
Antoine, Raphael; Baratoux, David; Lacogne, Julien; Lopez, Teodolina; Fauchard, Cyrille; Bretar, Frédéric; Arab-Sedze, Mélanie; Staudacher, Thomas; Jacquemoud, Stéphane; Pierrot-Deseilligny, Marc
2014-05-01
Thermal infrared data obtained in the [7-14 microns] spectral range are usually used in many Earth Science disciplines. These studies are exclusively based on the analysis of 2D information. In this case, a quantitative analysis of the surface energy budget remains limited, as it may be difficult to estimate the radiative contribution of the topography, the thermal influence of winds on the surface or potential imprints of subsurface flows on the soil without any precise DEM. The draping of a thermal image on a recent DEM is a common method to obtain a 3D thermal map of a surface. However, this method has many disadvantages i) errors can be significant in the orientation process of the thermal images, due to the lack of tie points between the images and the DEM; ii) the use of a recent DEM implies the use of another remote sensing technique to quantify the topography; iii) finally, the characterization of the evolution of a surface requires the simultaneous acquisition of thermal data and topographic information, which may be expensive in most cases. The stereophotogrammetry method allows to reconstitute the relief of an object from photos taken from different positions. Recently, substantial progress have been realized in the generation of high spatial resolution topographic surfaces using stereophotogrammetry. However, the presence of shadows, homogeneous textures and/or weak contrasts in the visible spectrum (e.g., flowing lavas, uniform lithologies) may prevent from the use of such method, because of the difficulties to find tie points on each image. Such situations are more favorable in the thermal infrared spectrum, as any variation in the thermal properties or geometric orientation of the surfaces may induce temperature contrasts that are detectable with a thermal camera. This system, usually functioning with a array sensor (Focal Plane Array) and an optical device, have geometric characteristics that are similar to digital cameras. Thus, it may be possible
Directory of Open Access Journals (Sweden)
Wen-Jing Zhou
2017-10-01
Full Text Available We present a simple yet effective method, without the need for any additional recording of intensity maps or tremendous iterative computations, to recover reference-wave intensity resulting from the complex hologram acquired by quadrature phase-shifting holography. This is achieved by utilizing a certain area of interest in the complex hologram. We select a particular area in the complex hologram where there is negligible diffraction from the test sample to estimate the reference-wave intensity. The calculated intensity value allows us to extract exact phase distribution of the object in the context of two-step-only quadrature phase-shifting holography (TSO-PSH without the zeroth-order beam and the twin image noise on the reconstruction plane. Computer simulation and experimental results have been performed to verify the effectiveness and feasibility of our proposed method.
Mathew, C. T.; Vidya, S.; Koshy, Jacob; Solomon, Sam; Thomas, Jijimon K.
2015-09-01
Infrared transparent ceramics found to have potential applications as infrared windows and domes in strategic defence and space missions. Synthesis of ultrafine nanostructured MgAl2O4 ceramics by a modified single step auto-igniting combustion technique, followed by sintering of the sample by resistive and resistive-microwave hybrid heating to high density and their excellent infrared transmission characteristics are presented in this paper. Structural characterisations of MgAl2O4 nanoparticles reveal that the as prepared powder is phase pure, with average crystallite size ∼15 nm and possess a cubic structure. Optical band gap calculated using the Kubelka-Munk method is 5.75 eV. The thermal stability of the nanopowder at elevated temperatures has been studied using thermo gravimetric analysis (TGA) and differential thermal analysis (DTA). Hybrid heating yield a substantial reduction in sintering temperature and soaking time relative to the conventional resistive heating, and the samples achieved >99% density by microwave-resistive hybrid heating. Scanning electron micrograph (SEM) showed that the pellets are well sintered. The pellet sintered by hybrid heating showed a better transmittance of ∼79% in the UV-Visible region and ∼82% in the mid IR region compared to pellet sintered by resistive heating which has ∼68% in the UV-Visible region and ∼66% in the mid IR region. The results confirm the effective use of nanocrystalline powders from modified combustion synthesis as starting material for the development of high quality IR transparent windows and domes. In addition the microwave hybrid sintering technique employed in the present study also contributes to the results of better transmittance characteristics in highly densified MgAl2O4 ceramic pellets.
International Nuclear Information System (INIS)
Sanchez de Alsina, O.L.; Scaricabarozzi, R.A.
1982-01-01
A matrix non-iterative method to calculate the periodical distribution in reactors with thermal regeneration is presented. In case of exothermic reaction, a source term will be included. A computer code was developed to calculate the final temperature distribution in solids and in the outlet temperatures of the gases. The results obtained from ethane oxidation calculation in air, using the Dietrich kinetic data are presented. This method is more advantageous than iterative methods. (E.G.) [pt
The Analysis Of Accuracy Of Selected Methods Of Measuring The Thermal Resistance Of IGBTs
Directory of Open Access Journals (Sweden)
Górecki Krzysztof
2015-09-01
Full Text Available In the paper selected methods of measuring the thermal resistance of an IGBT (Insulated Gate Bipolar Transistor are presented and the accuracy of these methods is analysed. The analysis of the measurement error is performed and operating conditions of the considered device, at which each measurement method assures the least measuring error, are pointed out. Theoretical considerations are illustrated with some results of measurements and calculations.
Photoacoustic spectroscopy and thermal relaxation method to evaluate corn moisture content
Pedrochi, F.; Medina, A. N.; Bento, A. C.; Baesso, M. L.; Luz, M. L. S.; Dalpasquale, V. A.
2005-06-01
In this study, samples of popcorn with different degrees of moisture were analyzed. The optical absorption bands at the mid infrared were measured using photoacoustic spectroscopy and were correlated to the sample moisture. The results were in agreement with moisture data determined by the well known reference method, the Karl Fischer. In addition, the thermal relaxation method was used to determine the sample specific heat as a function of the moisture content. The results were also in agreement with the two mentioned methods.
Wang, Han; Yan, Jie; Liu, Yongqian; Han, Shuang; Li, Li; Zhao, Jing
2017-11-01
Increasing the accuracy of wind speed prediction lays solid foundation to the reliability of wind power forecasting. Most traditional correction methods for wind speed prediction establish the mapping relationship between wind speed of the numerical weather prediction (NWP) and the historical measurement data (HMD) at the corresponding time slot, which is free of time-dependent impacts of wind speed time series. In this paper, a multi-step-ahead wind speed prediction correction method is proposed with consideration of the passing effects from wind speed at the previous time slot. To this end, the proposed method employs both NWP and HMD as model inputs and the training labels. First, the probabilistic analysis of the NWP deviation for different wind speed bins is calculated to illustrate the inadequacy of the traditional time-independent mapping strategy. Then, support vector machine (SVM) is utilized as example to implement the proposed mapping strategy and to establish the correction model for all the wind speed bins. One Chinese wind farm in northern part of China is taken as example to validate the proposed method. Three benchmark methods of wind speed prediction are used to compare the performance. The results show that the proposed model has the best performance under different time horizons.
A debugging method of the Quadrotor UAV based on infrared thermal imaging
Cui, Guangjie; Hao, Qian; Yang, Jianguo; Chen, Lizhi; Hu, Hongkang; Zhang, Lijun
2018-01-01
High-performance UAV has been popular and in great need in recent years. The paper introduces a new method in debugging Quadrotor UAVs. Based on the infrared thermal technology and heat transfer theory, a UAV is under debugging above a hot-wire grid which is composed of 14 heated nichrome wires. And the air flow propelled by the rotating rotors has an influence on the temperature distribution of the hot-wire grid. An infrared thermal imager below observes the distribution and gets thermal images of the hot-wire grid. With the assistance of mathematic model and some experiments, the paper discusses the relationship between thermal images and the speed of rotors. By means of getting debugged UAVs into test, the standard information and thermal images can be acquired. The paper demonstrates that comparing to the standard thermal images, a UAV being debugging in the same test can draw some critical data directly or after interpolation. The results are shown in the paper and the advantages are discussed.
Dynamic Snap-Through of Thermally Buckled Structures by a Reduced Order Method
Przekop, Adam; Rizzi, Stephen A.
2007-01-01
The goal of this investigation is to further develop nonlinear modal numerical simulation methods for application to geometrically nonlinear response of structures exposed to combined high intensity random pressure fluctuations and thermal loadings. The study is conducted on a flat aluminum beam, which permits a comparison of results obtained by a reduced-order analysis with those obtained from a numerically intensive simulation in physical degrees-of-freedom. A uniformly distributed thermal loading is first applied to investigate the dynamic instability associated with thermal buckling. A uniformly distributed random loading is added to investigate the combined thermal-acoustic response. In the latter case, three types of response characteristics are considered, namely: (i) small amplitude vibration around one of the two stable buckling equilibrium positions, (ii) intermittent snap-through response between the two equilibrium positions, and (iii) persistent snap-through response between the two equilibrium positions. For the reduced-order analysis, four categories of modal basis functions are identified including those having symmetric transverse, anti-symmetric transverse, symmetric in-plane, and anti-symmetric in-plane displacements. The effect of basis selection on the quality of results is investigated for the dynamic thermal buckling and combined thermal-acoustic response. It is found that despite symmetric geometry, loading, and boundary conditions, the anti-symmetric transverse and symmetric in-plane modes must be included in the basis as they participate in the snap-through behavior.
Schultz, A W
1968-09-01
A novel method has been developed for nondestructively determining the thermal inertia (k(p)C(p)) of solids near room temperature. The method involves heating, with radiant energy, for a short time a small area on the surface of a solid whose dimensions are such that it appears semi-infinite during this period. Simultaneously, the characteristically shaped temperature rise of the central region of this area is observed using an ir radiometer as the sensor. A comparison of this history with that for a reference standard yields the local thermal inertia value. The localized thermal conductivity and diffusivity can then be determined if the density and specific heat are known. Present technique precision for good conductors is slightly less than that for destructive measuring techniques.
A method for evaluating pressure locking and thermal binding of gate valves
Energy Technology Data Exchange (ETDEWEB)
Dogan, T.
1996-12-01
A method is described to evaluate the susceptibility of gate valves to pressure locking and thermal binding. Binding of the valve disc in the closed position due to high pressure water trapped in the bonnet cavity (pressure locking) or differential thermal expansion of the disk in the seat (thermal binding) represents a potential mechanism that can prevent safety-related systems from functioning when called upon. The method described here provides a general equation that can be applied to a given gate valve design and set of operating conditions to determine the susceptibility of the valve to fail due to disc binding. The paper is organized into three parts. The first part discusses the physical mechanisms that cause disc binding. The second part describes the mathematical equations. The third part discusses the conclusions.
Energy Technology Data Exchange (ETDEWEB)
Wood, Claire [CTSI; Bremner, Brenda [CTSI
2013-08-09
The Siletz Tribal Energy Program (STEP), housed in the Tribe’s Planning Department, will hire a data entry coordinator to collect, enter, analyze and store all the current and future energy efficiency and renewable energy data pertaining to administrative structures the tribe owns and operates and for homes in which tribal members live. The proposed data entry coordinator will conduct an energy options analysis in collaboration with the rest of the Siletz Tribal Energy Program and Planning Department staff. An energy options analysis will result in a thorough understanding of tribal energy resources and consumption, if energy efficiency and conservation measures being implemented are having the desired effect, analysis of tribal energy loads (current and future energy consumption), and evaluation of local and commercial energy supply options. A literature search will also be conducted. In order to educate additional tribal members about renewable energy, we will send four tribal members to be trained to install and maintain solar panels, solar hot water heaters, wind turbines and/or micro-hydro.
A new fourth-order Fourier-Bessel split-step method for the extended nonlinear Schroedinger equation
International Nuclear Information System (INIS)
Nash, Patrick L.
2008-01-01
Fourier split-step techniques are often used to compute soliton-like numerical solutions of the nonlinear Schroedinger equation. Here, a new fourth-order implementation of the Fourier split-step algorithm is described for problems possessing azimuthal symmetry in 3 + 1-dimensions. This implementation is based, in part, on a finite difference approximation Δ perpendicular FDA of 1/r (∂)/(∂r) r(∂)/(∂r) that possesses an associated exact unitary representation of e i/2λΔ perpendicular FDA . The matrix elements of this unitary matrix are given by special functions known as the associated Bessel functions. Hence the attribute Fourier-Bessel for the method. The Fourier-Bessel algorithm is shown to be unitary and unconditionally stable. The Fourier-Bessel algorithm is employed to simulate the propagation of a periodic series of short laser pulses through a nonlinear medium. This numerical simulation calculates waveform intensity profiles in a sequence of planes that are transverse to the general propagation direction, and labeled by the cylindrical coordinate z. These profiles exhibit a series of isolated pulses that are offset from the time origin by characteristic times, and provide evidence for a physical effect that may be loosely termed normal mode condensation. Normal mode condensation is consistent with experimentally observed pulse filamentation into a packet of short bursts, which may occur as a result of short, intense irradiation of a medium
Application of an analytical method for solution of thermal hydraulic conservation equations
Energy Technology Data Exchange (ETDEWEB)
Fakory, M.R. [Simulation, Systems & Services Technologies Company (S3 Technologies), Columbia, MD (United States)
1995-09-01
An analytical method has been developed and applied for solution of two-phase flow conservation equations. The test results for application of the model for simulation of BWR transients are presented and compared with the results obtained from application of the explicit method for integration of conservation equations. The test results show that with application of the analytical method for integration of conservation equations, the Courant limitation associated with explicit Euler method of integration was eliminated. The results obtained from application of the analytical method (with large time steps) agreed well with the results obtained from application of explicit method of integration (with time steps smaller than the size imposed by Courant limitation). The results demonstrate that application of the analytical approach significantly improves the numerical stability and computational efficiency.
Miranda Guedes, Rui
2018-02-01
Long-term creep of viscoelastic materials is experimentally inferred through accelerating techniques based on the time-temperature superposition principle (TTSP) or on the time-stress superposition principle (TSSP). According to these principles, a given property measured for short times at a higher temperature or higher stress level remains the same as that obtained for longer times at a lower temperature or lower stress level, except that the curves are shifted parallel to the horizontal axis, matching a master curve. These procedures enable the construction of creep master curves with short-term experimental tests. The Stepped Isostress Method (SSM) is an evolution of the classical TSSP method. Higher reduction of the required number of test specimens to obtain the master curve is achieved by the SSM technique, since only one specimen is necessary. The classical approach, using creep tests, demands at least one specimen per each stress level to produce a set of creep curves upon which TSSP is applied to obtain the master curve. This work proposes an analytical method to process the SSM raw data. The method is validated using numerical simulations to reproduce the SSM tests based on two different viscoelastic models. One model represents the viscoelastic behavior of a graphite/epoxy laminate and the other represents an adhesive based on epoxy resin.
Directory of Open Access Journals (Sweden)
Changchun Liu
2018-10-01
Full Text Available This paper studies the problem of scheduling a finite set of customers with stochastic service times for a single-server system. The objective is to minimize the waiting time of customers, the idle time of the server, and the lateness of the schedule. Because of the NP-hardness of the problem, the optimal schedule is notoriously hard to derive with reasonable computation times. Therefore, we develop a simulation based K-steps look-ahead selection method which can result in nearly optimal schedules within reasonable computation times. Furthermore, we study the different distributed service times, e.g., Exponential, Weibull and lognormal distribution and the results show that the proposed algorithm can obtain better results than the lag order approximation method proposed by Vink et al. (2015 [Vink, W., Kuiper, A., Kemper, B., & Bhulai, S. (2015. Optimal appointment scheduling in continuous time: The lag order approximation method. European Journal of Operational Research, 240(1, 213-219.]. Finally, a realistic appointment scheduling includes experiments to verify the good performance of the proposed method.
Ganta, D; Dale, E B; Rezac, J P; Rosenberger, A T
2011-08-28
A novel optical method has been developed for the measurement of thermal accommodation coefficients in the temperature-jump regime. The temperature dependence of the resonant frequency of a fused-silica microresonator's whispering-gallery mode is used to measure the rate at which the microresonator comes into thermal equilibrium with the ambient gas. The thermal relaxation time is related to the thermal conductivity of the gas under some simplifying assumptions and measuring this time as a function of gas pressure determines the thermal accommodation coefficient. Using a low-power tunable diode laser of wavelength around 1570 nm to probe a microsphere's whispering-gallery mode through tapered-fiber coupling, we have measured the accommodation coefficients of air, helium, and nitrogen on fused silica at room temperature. In addition, by applying thin-film coatings to the microsphere's surface, we have demonstrated that accommodation coefficients can be measured for various gases on a wide range of modified surfaces using this method. © 2011 American Institute of Physics
Thermographic method for evaluation of thermal influence of exterior surface colour of buildings
Wu, Yanpeng; Li, Deying; Jin, Rendong; Liu, Li; Bai, Jiabin; Feng, Jianming
2008-12-01
Architecture colour is an important part in urban designing. It directly affects the expressing and the thermal effect of exterior surface of buildings. It has proved that four factors affect the sign visibility, graphics, colour, lighting condition and age of the observers, and colour is the main aspect. The best method is to prevent the exterior space heating up in the first place, by reflecting heat away room the exterior surface.The colour of paint to coat building's exterior wall can have a huge impact on energy efficiency. While the suitable colour is essential to increasing the energy efficiency of paint colour during the warm summer months, those products also help paint colour efficiency and reduce heat loss from buildings during winter months making the interior more comfortable all year long. The article is based on analyzing the importance of architecture color design and existing urban colour design. The effect of external surface colour on the thermal behaviour of a building has been studied experimentally by Infrared Thermographic method in University of Science and technology Beijing insummer.The experimental results showed that different colour has quietly different thermal effect on the exterior surface of buildings. The thermal effect of carmine and fawn has nearly the same values. The main factor which is color express, give some suggest ting about urban color design. The investigation reveals that the use of suitable surface colour can dramatically reduce maximum the temperatures of the exterior wall. Keywords: architectural colour, thermal, thermographic
Chang, S. C.
1986-01-01
A two-step semidirect procedure is developed to accelerate the one-step procedure described in NASA TP-2529. For a set of constant coefficient model problems, the acceleration factor increases from 1 to 2 as the one-step procedure convergence rate decreases from + infinity to 0. It is also shown numerically that the two-step procedure can substantially accelerate the convergence of the numerical solution of many partial differential equations (PDE's) with variable coefficients.
Energy Technology Data Exchange (ETDEWEB)
Mitchell A. Plummer; Carl D. Palmer; Earl D. Mattson; Laurence C. Hull; George D. Redden
2011-07-01
The injection of cold fluids into engineered geothermal system (EGS) and conventional geothermal reservoirs may be done to help extract heat from the subsurface or to maintain pressures within the reservoir (e.g., Rose et al., 2001). As these injected fluids move along fractures, they acquire heat from the rock matrix and remove it from the reservoir as they are extracted to the surface. A consequence of such injection is the migration of a cold-fluid front through the reservoir (Figure 1) that could eventually reach the production well and result in the lowering of the temperature of the produced fluids (thermal breakthrough). Efficient operation of an EGS as well as conventional geothermal systems involving cold-fluid injection requires accurate and timely information about thermal depletion of the reservoir in response to operation. In particular, accurate predictions of the time to thermal breakthrough and subsequent rate of thermal drawdown are necessary for reservoir management, design of fracture stimulation and well drilling programs, and forecasting of economic return. A potential method for estimating migration of a cold front between an injection well and a production well is through application of reactive tracer tests, using chemical whose rate of degradation is dependent on the reservoir temperature between the two wells (e.g., Robinson 1985). With repeated tests, the rate of migration of the thermal front can be determined, and the time to thermal breakthrough calculated. While the basic theory behind the concept of thermal tracers has been understood for some time, effective application of the method has yet to be demonstrated. This report describes results of a study that used several methods to investigate application of reactive tracers to monitoring the thermal evolution of a geothermal reservoir. These methods included (1) mathematical investigation of the sensitivity of known and hypothetical reactive tracers, (2) laboratory testing of novel
Hofman, R.; Vreijling, M.P.W.; Ferrari, G.M.; Wit, J.H.W. de
1998-01-01
The use of thermal spray stainless steel coatings for protection of low alloyed steels against different types of corrosion is limited due to high porosity levels and oxide inclusions. In this paper electrochemical methods like corrosion potential monitoring and cyclic voltammetry are reported to
Prud'Homme, Robert K. (Inventor); Aksay, Ilhan A. (Inventor)
2011-01-01
A conductive ink containing a conductive polymer, wherein the conductive polymer contains at least one polymer and a modified graphite oxide material, which is a thermally exfoliated graphite oxide with a surface area of from about 300 sq m/g to 2600 sq m/g, and it use in a method for making a conductive circuit.
Computational analysis of thermal transfer and related phenomena based on the Fourier method
Vala, Jiří; Jarošová, Petra
2017-07-01
Modelling and simulation of thermal processes, based on the principles of classical thermodynamics, requires numerical analysis of partial differential equations of evolution of the parabolic type. This paper demonstrates how the generalized Fourier method can be applied to the development of robust and effective computational algorithms, with the direct application to the design and performance of buildings with controlled energy consumption.
A surfactant-thermal method to prepare four new three-dimensional heterometal-organic frameworks
Gao, Junkuo
2013-01-01
Here, we report on a surfactant-thermal method to prepare four new 3-D crystalline heterometal-organic frameworks (HMOFs). The results indicate that our new strategy for growing crystalline materials in surfactant media has great potential for the synthesis of novel MOFs with various structures. © 2013 The Royal Society of Chemistry.
Wu, Jie; Zhou, Quno; Wu, Li-Ming; Au, Jian-Dong; Sun, Su-Qin; Hu, Fu-Liang
2010-02-01
Six kinds of bee pollens, including apricot pollen, lotus pollen, rape pollen, camellia pollen, watermelon pollen and corn poppy pollen, were identified non-destructively by Fourier transform infrared spectroscopy (FTIR) combined with derivative spectra and two-dimensional correlation spectroscopy (2D) in the present article. Compared with conventional IR spectra of samples, some certain differences were found in the characteristic peaks of proteins, lipids and carbohydrates. Obvious differences of the six kinds of bee pollens were found in the second derivative spectra. And in the 2D-IR correlation spectra, the samples presented the differences in the position and intensity of the autopeaks and correlation peak clusters. Therefore, the three-step IR macro-fingerprint provides a more rapid and effective method for the identification of different kinds of bee pollens.
Veldkamp, Ted; Wada, Yoshihide; Aerts, Jeroen; Ward, Phillip
2016-01-01
Water scarcity -driven by climate change, climate variability, and socioeconomic developments- is recognized as one of the most important global risks, both in terms of likelihood and impact. Whilst a wide range of studies have assessed the role of long term climate change and socioeconomic trends on global water scarcity, the impact of variability is less well understood. Moreover, the interactions between different forcing mechanisms, and their combined effect on changes in water scarcity conditions, are often neglected. Therefore, we provide a first step towards a framework for global water scarcity risk assessments, applying probabilistic methods to estimate water scarcity risks for different return periods under current and future conditions while using multiple climate and socioeconomic scenarios.
Directory of Open Access Journals (Sweden)
James A Bassuk
Full Text Available The purpose of this study was to illustrate the application of A3 Problem Solving Reports of the Toyota Production System to our research vivarium through the methodology of Continuous Performance Improvement, a lean approach to healthcare management at Seattle Children's (Hospital, Research Institute, Foundation. The Report format is described within the perspective of a 10-step scientific method designed to realize measurable improvements of Issues identified by the Report's Author, Sponsor and Coach. The 10-step method (Issue, Background, Current Condition, Goal, Root Cause, Target Condition, Countermeasures, Implementation Plan, Test, and Follow-up was shown to align with Shewhart's Plan-Do-Check-Act process improvement cycle in a manner that allowed for quantitative analysis of the Countermeasure's outcomes and of Testing results. During fiscal year 2012, 9 A3 Problem Solving Reports were completed in the vivarium under the teaching and coaching system implemented by the Research Institute. Two of the 9 reports are described herein. Report #1 addressed the issue of the vivarium's veterinarian not being able to provide input into sick animal cases during the work day, while report #7 tackled the lack of a standard in keeping track of weekend/holiday animal health inspections. In each Report, a measurable Goal that established the basis for improvement recognition was present. A Five Whys analysis identified the Root Cause for Report #1 as historical work patterns that existed before the veterinarian was hired on and that modern electronic communication tools had not been implemented. The same analysis identified the Root Cause for Report #7 as the vivarium had never standardized the process for weekend/holiday checks. Successful outcomes for both Reports were obtained and validated by robust audit plans. The collective data indicate that vivarium staff acquired a disciplined way of reporting on, as well as solving, problems in a manner
Bassuk, James A; Washington, Ida M
2013-01-01
The purpose of this study was to illustrate the application of A3 Problem Solving Reports of the Toyota Production System to our research vivarium through the methodology of Continuous Performance Improvement, a lean approach to healthcare management at Seattle Children's (Hospital, Research Institute, Foundation). The Report format is described within the perspective of a 10-step scientific method designed to realize measurable improvements of Issues identified by the Report's Author, Sponsor and Coach. The 10-step method (Issue, Background, Current Condition, Goal, Root Cause, Target Condition, Countermeasures, Implementation Plan, Test, and Follow-up) was shown to align with Shewhart's Plan-Do-Check-Act process improvement cycle in a manner that allowed for quantitative analysis of the Countermeasure's outcomes and of Testing results. During fiscal year 2012, 9 A3 Problem Solving Reports were completed in the vivarium under the teaching and coaching system implemented by the Research Institute. Two of the 9 reports are described herein. Report #1 addressed the issue of the vivarium's veterinarian not being able to provide input into sick animal cases during the work day, while report #7 tackled the lack of a standard in keeping track of weekend/holiday animal health inspections. In each Report, a measurable Goal that established the basis for improvement recognition was present. A Five Whys analysis identified the Root Cause for Report #1 as historical work patterns that existed before the veterinarian was hired on and that modern electronic communication tools had not been implemented. The same analysis identified the Root Cause for Report #7 as the vivarium had never standardized the process for weekend/holiday checks. Successful outcomes for both Reports were obtained and validated by robust audit plans. The collective data indicate that vivarium staff acquired a disciplined way of reporting on, as well as solving, problems in a manner consistent with high
Mashima, Izumi; Theodorea, Citra Fragrantia; Thaweboon, Boonyanit; Thaweboon, Sroisiri; Nakazawa, Futoshi
2016-01-01
Six Veillonella species have been frequently isolated from human oral cavities including infectious sites. Recently, it was reported that diet, smoking, and possibly socioeconomic status can influence the bacterial profile in oral cavities. In addition, oral hygiene habits may also influence oral microbiota in terms of both numbers and diversity of microorganisms. In this study, the identification of Veillonella species in tongue biofilms of Thai children, divided into three groups dependent on their status of oral hygiene. For this, we used a novel one-step PCR method with species-specific primer sets based on sequences of the rpoB gene. As shown in the results, the number of isolates of Veillonella species was 101 strains from only 10 of 89 subjects. However, the total number of bacteria was high for all subjects. Since it was reported in previous studies that Veillonella species were easy to isolate in human tongue biofilms at high numbers, the results obtained in this study may suggest country- or age-specific differences. Moreover, Veillonella species were detected predominantly in subjects who had poor oral hygiene compared to those with good or moderate oral hygiene. From these results, there is a possibility that Veillonella species may be an index of oral hygiene status. Furthermore, V. rogosae was a predominant species in tongue biofilms of Thai children, whereas V. parvula and V. denticariosi were not isolated at all. These characteristics of the distribution and frequency of Veillonella species are similar to those reported in previous studies. Although further studies are needed in other countries, in this study, a successful novel one-step PCR method was established to detect Veillonella species in human oral cavities easily and effectively. Furthermore, this is the first report investigating the distribution and frequency of Veillonella species in tongue biofilms of Thai children. PMID:27326455
Johnson, C. W.
2010-09-01
Configuration management ensures that the requirements and constraints, identified in previous stages of development, are preserved throughout the design, implementation and operation of complex systems. Space-related, software systems pose particular problems because, for instance, it can be hard to determine what code is actually running on a platform as successive updates are performed over many months of remote operation. It is, therefore, important we learn as much as possible from previous mishaps that have involved configuration management; given that software continues to play a critical role in the safety of many space missions. The following pages extend the US Air Force’s 8-Step Method to identify lessons learned from space related incidents. This approach builds on Boyd’s OODA(Observe, Orient, Decide and Act) Loop and provides a common framework for the analysis of these complex incidents. It is important to stress that the application of an existing general approach to problem solving, rather than the development of a specific approach for configuration management, is intended to reduce training costs and to increase the value added from existing investments in the use of the 8-Step Method. Many specialised software engineering techniques are not used because they cannot easily be applied within the financial limits and deadlines that constrain most space programmes. The closing sections of this paper identify areas for further work; in particular, we stress the importance of links with recent European Space Agency problem solving techniques that support the early-stage development of long duration space missions.
Analysis of the thermal effect in diode end-pumped Er:YAG lasers by using Finite Element Method
Wang, Yujia; Wang, Qing; Na, QuanXin; Zhang, Yixuan; Gao, Mingwei; Zhang, Meng
2018-01-01
A new method for combining Finite Element Method (FEM) thermal analysis and thermo-mechanical coupling method for calculating the thermal lensing values in diode end-pumped Er:YAG lasers is proposed. A finite-element model is used to simulate the thermal effects in different Er:YAG crystals with pumping scenarios. The influences of pump powers, crystal absorption coefficients and crystal sizes on the Er:YAG thermal effects are discussed, and the relationship between the thermal effects and thermal lensing effects is analysed. A thermo-mechanical coupling model is also constituted for finite-element analysis based on the above results, and the focal length of the Er:YAG crystal with different pump powers are obtained by using this thermo-mechanical coupling model. The predicted thermal lensing values are compared with experimental results, which agree well with the simulated results.
A comparison of two transient methods of measuring thermal conductivity of particulate samples.
Scott, R. W.; Fountain, J. A.; West, E. A.
1973-01-01
A comparison is made of the line source (LS) method and the differential line source (DLS) method of measuring thermal conductivity of particulate materials in vacuum. The DLS method requires more instrumentation in the measuring circuitry (an additional amplifier and a differentiating circuit), but since it does not require a stable temperature to initiate a test, it does not need a sample temperature control system. DLS tests can be taken as the temperature in the samples is rising from liquid nitrogen temperature to room temperature. This eliminates the practice of extrapolating thermal conductivity over this large temperature range. Also, the advantages of reduced test time, data reduction time, and small sample temperature rise enable the experimenter to take about 7-12 DLS tests in the time of 2 LS tests. Test data from the two methods agree very well.
Effective methods of solving of model equations of certain class of thermal systems
International Nuclear Information System (INIS)
Lach, J.
1985-01-01
A number of topics connected with solving of model equations of certain class of thermal systems by the method of successive approximations is touched. A system of partial differential equations of the first degree, appearing most frequently in practical applications of heat and mass transfer theory is reduced to an equivalent system of Volterra integral equations of the second kind. Among a few sample applications the thermal processes appearing in the fuel channel of nuclear reactor are solved. The theoretical analysis is illustrated by the results of numerical calculations given in tables and diagrams. 111 refs., 17 figs., 16 tabs. (author)
CHF predictor derived from a 3D thermal-hydraulic code and an advanced statistical method
International Nuclear Information System (INIS)
Banner, D.; Aubry, S.
2004-01-01
A rod bundle CHF predictor has been determined by using a 3D code (THYC) to compute local thermal-hydraulic conditions at the boiling crisis location. These local parameters have been correlated to the critical heat flux by using an advanced statistical method based on spline functions. The main characteristics of the predictor are presented in conjunction with a detailed analysis of predictions (P/M ratio) in order to prove that the usual safety methodology can be applied with such a predictor. A thermal-hydraulic design criterion is obtained (1.13) and the predictor is compared with the WRB-1 correlation. (author)
Multiple objective optimization of hydro-thermal systems using Ritz's method
Directory of Open Access Journals (Sweden)
L. Bayón Arnáu
2000-01-01
Full Text Available This paper examines the applicability of the Ritz method to multi-objective optimization of hydro-thermal systems. The algorithm proposed is aimed to minimize an objective functional that incorporates the cost of energy losses, the conventional fuel cost and the production of atmospheric emissions such as NOx and SO2 caused by the operation of fossil-fueled thermal generation. The formulation includes a general layout of hydro-plants that may form multi-chains of reservoir network.
A facile one-step method for synthesising a parallelogram-shaped single-crystalline ZnO nanosheet
Energy Technology Data Exchange (ETDEWEB)
Zhang, Renyun, E-mail: renyun.zhang@miun.se; Hummelgård, Magnus; Olin, Håkan
2014-05-01
Graphical abstract: - Highlights: • A simple method to synthesise ZnO nanosheets is described. • Parallelogram-shaped ZnO nanosheets were obtained with single-crystalline structure. • A specific mechanism of the growth was suggested. - Abstract: ZnO nanosheets are found to be useful in many fields such as sensors and electronics. Non-uniform-shaped ZnO nanosheets are synthesised using several methods; moreover, uniformly shaped ones are less studied. Here, we report on a simple one-step method to synthesise parallelogram-shaped single-crystalline ZnO nanosheets. By controlling the reaction of Zn(NO{sub 3}){sub 2} and hexamethylenetetramine (HMT) in ethanol, average 30 nm-thick nanosheets with a high aspect ratio of 1:100 were obtained. The parallelogram angles were between 97° and 99°. Transmission electron microscopy (TEM) diffraction and X-ray diffraction (XRD) showed that the nanosheets were wurtzite-structured single-crystalline ZnO. Moreover, a growth mechanism of these parallelogram nanosheets is suggested based on the experimental results. These results suggest a new simple solution process to synthesise uniformly shaped ZnO nanosheets allowing large-scale production to be employed.
Directory of Open Access Journals (Sweden)
Raquel M. Fernández
2013-01-01
Full Text Available Preimplantation genetic diagnosis (PGD of single gene disorders, combined with HLA matching (PGD-HLA, has emerged as a tool for couples at risk of transmitting a genetic disease to select unaffected embryos of an HLA tissue type compatible with that of an existing affected child. Here, we present a novel one-step multiplex PCR to genotype a spectrum of STRs to simultaneously perform HLA typing and PGD for -thalassemia. This method is being routinely used for PGD-HLA cycles in our department, with a genotyping success rate of 100%. As an example, we present the first successful PGD-HLA typing in Spain, which resulted in the birth of a boy and subsequent successful HSC transplantation to his affected brother, who is doing well 4 years following transplantation. The advantage of our method is that it involves only a round of single PCR for multiple markers amplification (up to 10 markers within the HLA and 6 markers at the -globin loci. This strategy has allowed us to considerably reduce the optimization of the PCR method for each specific PGD-HLA family as well as the time to obtain molecular results in each cycle.
Directory of Open Access Journals (Sweden)
Nikola Štambuk
2014-05-01
Full Text Available Antisense peptide technology is a valuable tool for deriving new biologically active molecules and performing peptide–receptor modulation. It is based on the fact that peptides specified by the complementary (antisense nucleotide sequences often bind to each other with a higher specificity and efficacy. We tested the validity of this concept on the example of human erythropoietin, a well-characterized and pharmacologically relevant hematopoietic growth factor. The purpose of the work was to present and test simple and efficient three-step procedure for the design of an antisense peptide targeting receptor-binding site of human erythropoietin. Firstly, we selected the carboxyl-terminal receptor binding region of the molecule (epitope as a template for the antisense peptide modeling; Secondly, we designed an antisense peptide using mRNA transcription of the epitope sequence in the 3'→5' direction and computational screening of potential paratope structures with BLAST; Thirdly, we evaluated sense–antisense (epitope–paratope peptide binding and affinity by means of fluorescence spectroscopy and microscale thermophoresis. Both methods showed similar Kd values of 850 and 816 µM, respectively. The advantages of the methods were: fast screening with a small quantity of the sample needed, and measurements done within the range of physicochemical parameters resembling physiological conditions. Antisense peptides targeting specific erythropoietin region(s could be used for the development of new immunochemical methods. Selected antisense peptides with optimal affinity are potential lead compounds for the development of novel diagnostic substances, biopharmaceuticals and vaccines.
Levy, D; Davies, J; O'Hehir, R; Suphioglu, C
2001-06-01
Purified proteins are mandatory for molecular, immunological and cellular studies. However, purification of proteins from complex mixtures requires specialised chromatography methods (i.e., gel filtration, ion exchange, etc.) using fast protein liquid chromatography (FPLC) or high-performance liquid chromatography (HPLC) systems. Such systems are expensive and certain proteins require two or more different steps for sufficient purity and generally result in low recovery. The aim of this study was to develop a rapid, inexpensive and efficient gel-electrophoresis-based protein purification method using basic and readily available laboratory equipment. We have used crude rye grass pollen extract to purify the major allergens Lol p 1 and Lol p 5 as the model protein candidates. Total proteins were resolved on large primary gel and Coomassie Brilliant Blue (CBB)-stained Lol p 1/5 allergens were excised and purified on a secondary "mini"-gel. Purified proteins were extracted from unstained separating gels and subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblot analyses. Silver-stained SDS-PAGE gels resolved pure proteins (i.e., 875 microg of Lol p 1 recovered from a 8 mg crude starting material) while immunoblot analysis confirmed immunological reactivity of the purified proteins. Such a purification method is rapid, inexpensive, and efficient in generating proteins of sufficient purity for use in monoclonal antibody (mAb) production, protein sequencing and general molecular, immunological, and cellular studies.
Directory of Open Access Journals (Sweden)
James Rouse
2016-01-01
Full Text Available The threat of thermal fatigue is an increasing concern for thermal power plant operators due to the increasing tendency to adopt “two-shifting” operating procedures. Thermal plants are likely to remain part of the energy portfolio for the foreseeable future and are under societal pressures to generate in a highly flexible and efficient manner. The Green’s function method offers a flexible approach to determine reference elastic solutions for transient thermal stress problems. In order to simplify integration, it is often assumed that Green’s functions (derived from finite element unit temperature step solutions are temperature independent (this is not the case due to the temperature dependency of material parameters. The present work offers a simple method to approximate a material’s temperature dependency using multiple reference unit solutions and an interpolation procedure. Thermal stress histories are predicted and compared for realistic temperature cycles using distinct techniques. The proposed interpolation method generally performs as well as (if not better than the optimum single Green’s function or the previously-suggested weighting function technique (particularly for large temperature increments. Coefficients of determination are typically above 0 . 96 , and peak stress differences between true and predicted datasets are always less than 10 MPa.
Numerical modeling of the line-source methods for thermal conductivity measurement
LEE, Y.; Keehm, Y.
2012-12-01
The line-source methods using a needle probe or a half-space probe have been used to measure thermal conductivity of rocks and soils in heat flow study. Though those are widely used, measurement errors have not been investigated systematically. Errors in line-source methods are caused by sample size, needle diameter, contact between a sample and a probe, and thermal conductivity of thermal compound. Since thermal conductivity of most rocks and soils ranges from 1 to 7 W/mK, a few percent of error can cause unreliable estimate of heat flow. We conducted a series of numerical modeling studies to quantify various measurement errors in the line-source methods. In the case of the needle probe with 2 mm diameter and 70 mm length, the measurement errors by the sample diameter range from 0.2% for 150 mm to 15.1% for 10 mm. When we fixed the needle length as 70 mm and varied the needle diameters from 2 to 5 mm, the errors in the measured thermal conductivity range from 0.2% for 2 mm to 24.0% for 5 mm. This clearly shows that the needle with thicker diameter does not satisfy the mathematical assumption of the infinite line-source model. Thermal resistance at the contact between the rock sample and the needle also caused considerable measurement errors. When we varied the gap between the rock sample and the needle that is filled with thermal compound (0.29 W/mK), errors range from 2.7% for 0.05 mm gap to 47.7% for 0.3 mm gap. If the gap is filled with air (0.0257 W/mK), the error ranges 80.3% for 0.05 mm gap to 87.4% for 0.1 mm gap. Numerical results show that one should take special care in reducing the gap between the rock sample and the needle probe, and should fill the gap with thermal compound, since the contact can cause significant amounts of measurement errors. In addition, the thermal conductivity of thermal compound plays an important role in reducing thermal resistance between the rock sample and the needle. The errors range from 2.4% for thermal compound with 0
Thermal conductivity measurements in soil using an instrument based on the cylindrical probe method
Nicolas, J.; André, Ph.; Rivez, JF.; Debbaut, V.
1993-03-01
The article discusses the underlying hypothesis, the limits, the range of application, and the practical operation of a versatile thermal conductivity analyzer based on a transient cylindrical probe method. The best expected precision for the conductivity determination appears to be ˜±10%. A compact analyzer, integrating all the apparatus' components in the same unit, has been specifically designed for environmental research in the field. Calibration received special attention regarding thermal conductivity values in the range 0.1-3 W/mK. The analyzer was tested on seven materials, in field conditions, and discrepancies from published conductivity values did not exceed 9%. Several checks were performed in the laboratory to study the influence of experimental conditions, such as the probe insertion technique. The cylindrical probe method appears well suited to powdered materials, but may also be applied to viscous liquids and solid matter. As an application, the cylindrical probe was used to characterize nine soils from the Belgian Lorraine. After soil analysis in the dry state, thermal conductivity of each sample was determined at different moisture contents. The transient cylindrical probe method proved to be quick and easy, whether in situ or on samples in the laboratory. It is a powerful tool which can map a country's soil thermal properties.
Mesnyankin, Sergei Yu; Vikulov, Aleksei G.; Vikulov, Dmitrii G.
2009-09-01
The past 40 years of theoretical and experimental research on contact heat transfer are reviewed. Thermophysical and mechanical processes involved in heat flow propagation through various kinds of solid-solid joints are considered. Analytical and semiempirical expressions are presented, which simulate these processes both under vacuum conditions and in the presence of a heat-conducting medium in gaps. Reasons for the experimentally examined heat flux rectification are explained. Studies on thermal contact under a nonstationary regime are covered, as is the possibility of applying classical heat conduction theory to describing the contact thermal properties. A thermodynamic interpretation of the thermal contact resistance is suggested and basic approaches to the study of contact phenomena are described. The heat conduction in nanosystems is briefly reviewed. Theoretical problems yet to be solved are pointed out and possible solution methods suggested.