123 results on '"Thermal analysis -- Methods"'
Search Results
2. FTIR and thermal analyses of intermolecular interactions in poly(trimethylene terephthalate)/phenoxy blends
- Author
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Farmahini-Farahani, Madjid, Jafari, Seyed-Hassan, Khonakdar, Hosein Ali, Yavari, Ahmad, and Melati, Amir
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Thermal analysis -- Methods ,Fourier transform infrared spectroscopy -- Methods ,Methyl groups -- Chemical properties -- Composition ,Polymeric composites -- Chemical properties -- Composition ,Bisphenol-A -- Chemical properties -- Composition ,Hydrogen bonding -- Research ,Engineering and manufacturing industries ,Science and technology - Abstract
Intermolecular interactions in the blends of poly(trimethylene terephthalate)/phenoxy resin of bisphenol A prepared by melt mixing in a microcompounder were studied using Fourier transform infrared (FTIR) spectroscopy and thermal analysis. The FTIR results revealed the characteristic bands of the blend constituents along with the bands showing interassociated, self-associated, and nonassociated hydrogen bonding in the blends. It was found that the self-associated hydrogen bonds in the blends were favorable over the interassociated bonds. On the other hand, using the melting point depression, the interaction parameter of the blends was calculated to be about 0.047. The positive value of the interaction parameter and low degree of interassociated hydrogen bonding in the blends suggest the immiscibility of the blends, which is confirmed by scanning electron microscopy observations as well as dynamic mechanical analysis. However, for chemically reacted compositions, the blends were changed to homogenous systems. POLYM. ENG. SCI., 51:518-525, 2011. [C]2010 Society of Plastics Engineers, INTRODUCTION Polymer blends have been of importance in the engineering industry in the past decades. Among the attempts that have been done in the field of polymer blends, a large [...] more...
- Published
- 2011
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- View/download PDF
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3. Researchers from North China Electric Power University Describe Findings in Information Technology (Multi-condition identification of thermal process data based on mixed constraints semi-supervised clustering)
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Multilevel analysis -- Usage -- Methods ,Thermal analysis -- Methods ,Machine learning -- Methods -- Analysis ,Health ,Science and technology - Abstract
2022 JUL 1 (NewsRx) -- By a News Reporter-Staff News Editor at Science Letter -- Researchers detail new data in information technology. According to news reporting from North China Electric [...]
- Published
- 2022
4. Thermodynamic analysis of part-flow cycle supercritical C[O.sub.2] gas turbines
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Utamura, Motoaki
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Carbon dioxide -- Mechanical properties ,Carbon dioxide -- Thermal properties ,Gas-turbines -- Mechanical properties ,Gas-turbines -- Thermal properties ,Thermal analysis -- Methods ,Engineering and manufacturing industries ,Science and technology - Abstract
Cycle characteristics of closed gas turbines using supercritical carbon dioxide as a working fluid are investigated. It is found that an anomalous behavior of the physical properties of C[O.sub.2] at the pseudocritical point may limit the heat exchange rate of a regenerative heat exchanger due to the presence of a pinch point inside the regenerative heat exchanger Taking such a pinch problem into consideration, the cycle efficiency of the Brayton cycle is assessed. Its value is found to be limited to 39% degraded by 8% compared with the case without the pinch present inside. As an alternative, a part-flow cycle is investigated and its operable range has been identified. It is revealed that the part-flow cycle is effective to recover heat transfer capability and may achieve the cycle thermal efficiency of 45% under maximum operating conditions of 20 MPa and 800 K. Optimal combination of turbine expansion ratio and a part-flow ratio is 2.5 and 0.68, respectively. Parametric study is carried out. In neither compressor nor turbine, deteriorated adiabatic efficiency may affect cycle efficiency significantly. However, pressure drop characteristics of heat exchangers govern the cycle efficiency. [DOI: 10.1115/1.4001052] Keywords: carbon dioxide, supercritical, part-flow cycle, microchannel, pressure loss, recuperator more...
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- 2010
5. Quantitative characterization of multicomponent polymers by sample-controlled thermal analysis
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Sanchez-Jimenez, Pedro E., Perez-Maqueda, Luis A., Crespo-Amoros, Jose E., Lopez, Juan, Perejon, Antonio, and Criado, Jose M.
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Polymers -- Identification and classification ,Polymers -- Chemical properties ,Thermal analysis -- Methods ,Chemistry - Abstract
This paper explores the potential of sample-controlled thermal analysis (SCTA) in order to perform compositional analysis of multicomponent polymeric materials by means of thermogravimetric experiments. In SCTA experiments, the response of the sample to the temperature determines the evolution of the temperature by means of a feedback system; thus, what is controlled is not the temperature--time profile, as in conventional analysis, but rather the evolution of the reaction rate with time. The higher resolving power provided by the technique has been used for determining the composition of polymer blends composed of polyvinyl chloride (PVC) and different commercial plasticizers, a system where the individual components have very similar thermal stabilities, thereby rendering useless thermogravimetric experiments run under conventional conditions. Different SCTA procedures, such as constant rate thermal analysis (CRTA), which has received special attention, and high-resolution and stepwise isothermal analysis have been tested, and the results obtained have been compared with linear heating rate technique. It has been proven that CRTA can be used to effectively determine the exact composition of the blend. 10.1021/ac101651g more...
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- 2010
6. A comparative thermal analysis of slot-entry and hole-entry hybrid journal bearings lubricated with non-Newtonian lubricant
- Author
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Garg, H.C., Kumar, Vijay, and Sharda, H.B.
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Thermal analysis -- Methods ,Thermal analysis -- Comparative analysis ,Journal bearings -- Equipment and supplies ,Journal bearings -- Thermal properties ,Journal bearings -- Mechanical properties ,Lubrication and lubricants -- Mechanical properties ,Lubrication and lubricants -- Thermal properties ,Science and technology - Abstract
The effect of viscosity variation due to temperature rise and non-Newtonian behavior of the lubricant on the performance of hole-entry and slot-entry hybrid journal bearings system is the focus of this investigation. The performance characteristics of nonrecessed hybrid journal bearings operating with different flow controlling devices, i.e., constant flow valve, capillary, orifice, and slot restrictors, have been compared. Finite element method has been used to solve the Reynolds equation governing the flow of lubricant in the bearing clearance space along with the restrictor flow equation, energy equation and conduction equation using suitable iterative technique. The non-Newtonian lubricant has been assumed to follow the cubic shear stress law. The results indicate that variation in viscosity due to rise in temperature and non-Newtonian behavior of the lubricant affects the performance of nonrecessed hybrid journal bearing system quite significantly. The results further indicate that bearing performance can be improved by selecting a particular bearing configuration in conjunction with a suitable compensating device. [DOI: 10.1115/1.4002034] Keywords: hybrid journal bearing, slot-entry, hole-entry, constant flow valve, capillary, orifice, non-Newtonian lubricant, thermal effects more...
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- 2010
7. Electrical and thermal analyses of parallel single-conductor cable installations
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Du, Patrick Y. and Wang, X.H.
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Electrical cables -- Research ,Electrical cables -- Models ,Electrical cables -- Installation ,Electric currents -- Distribution ,Electric currents -- Analysis ,Thermal analysis -- Methods ,Energy dissipation -- Analysis ,Electrical wire and cable industry -- Product development ,Technology installation instructions ,Company distribution practices ,Business ,Computers ,Electronics ,Electronics and electrical industries - Published
- 2010
8. Thermomechanical analysis of film-on-substrate system with temperature-dependent properties
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Huang, YongAn, Yin, ZhouPing, and Xiong, YouLun
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Thermal analysis -- Methods ,Dielectric films -- Mechanical properties ,Dielectric films -- Thermal properties ,Dielectric films -- Testing ,Thin films -- Mechanical properties ,Thin films -- Thermal properties ,Thin films -- Testing ,Materials -- Testing ,Materials -- Methods ,Materials -- Technology application ,Technology application ,Science and technology - Abstract
Thermomechanical analysis of global and local buckling is presented to show temperature effects on the stress/strain and shape of a film-on-substrate system. First, the strain is expressed as a function of three key temperatures (room, working, and deposit temperatures). Through sensitivity analysis on temperature, polydimethylsiloxane (PDMS) selection is determined to theoretically design film-on-substrate systems with the minimum variation in stress caused by temperatures. Then, the wrinkling behaviors are studied to establish the relationships of critical strain, wavelength, and amplitude with temperature. In addition, the critical working temperature is determined for local buckling. The approximate semi-analytical solution and the finite element simulation are compared by the use of a two-dimensional case of film on a half-space substrate. [DOI: 10.1115/1.4000927] Keywords: flexible electronics, thermomechanical buckling, thin film, multiphysics simulation, elastomer more...
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- 2010
9. Computation of arrester thermal stability
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Zhong Zheng, Boggs, Steven A., and Nishiwaki, Susumu
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Lightning-arresters -- Evaluation ,Thermal analysis -- Methods ,Business ,Computers ,Electronics ,Electronics and electrical industries - Published
- 2010
10. Study on the thermal accumulation and distribution inside a parked car cabin
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Kayiem, Hussain H. Al-, Sidik, M. Firdaus Bin M., and Munusammy, Yuganthira R.A.L.
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Thermal analysis -- Methods ,Automobiles -- Heating, cooling and ventilation ,Automobiles -- Design and construction ,Science and technology - Abstract
Problem statement: When a vehicle is parked under the direct sun, the accumulated heat is affecting many interiors inside the vehicle cabin, such as the vinyl materials of the dashboard, the leather covers and the electronic components. Also, it represents an uncomfortable operating period for the passengers. The studies under this topic are entitled by the vehicle manufacturers as 'Vehicle Cabin Comfort'. Approach: In the present study, experimental and numerical analyses were conducted. The experimental results were obtained from measurements on a salon car parked in un-shaded area. Six different cases had been investigated consisting of full windows closing case, four different windows opening settings and sun shade usage case. The temperature at 12 different locations inside the car had been recorded for many days and the mean values are used as initial and boundary conditions to run the 3-D computational simulation. The CFD simulation was carried out by FLUENT software. Results: Both experimental and CFD simulation results revealed that the most hot air was accumulated in the top part of the cabin and natural circulation take place with large scale cavity due to natural heat transfer from the dashboard and the rear windshield. The drop down of the front side windows by 20 mm caused reduction in the front air gap by 20%. The sunshade on the front had considerably reduced the heat accumulation inside the cabin, where the dashboard surface temperature dropped by 26% and the maximum air temperature was found to be 27% lower. Conclusion: The use of the sunshade and/or dropdown windows on both sides reduced the heat accumulation due to fresh air exchange with the exterior environment. Key words: Vehicle cabin comfort, CFD simulation, thermal analysis, cars ventilation, INTRODUCTION The problem that is faced by many car users today is a hot interior after certain hours of parking in open air or un-shaded parking area. The heat under [...] more...
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- 2010
11. Serpentine minerals discrimination by thermal analysis
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Viti, Cecilia
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Chrysotile -- Properties ,Serpentine -- Properties ,Thermal analysis -- Methods ,Crystals -- Structure ,Crystals -- Observations ,Earth sciences - Abstract
This paper reports a complete set of TG, DTG, and DTA data, coupled with emitted gas analysis, for well-constrained, almost pure serpentine samples. Serpentine dehydroxylation takes place between 550 and 800 [degrees]C, with DTG and DTA peak temperatures progressively decreasing from antigorite (720 and 715 [degrees]C, respectively) to lizardite (708 and 714 [degrees]C), polygonal serpentine (685 and 691 [degrees]C), and chrysotile (650 and 654 [degrees]C). Antigorite has an additional diagnostic signal at ~740-760 [degrees]C, always absent in the other serpentines, and dependent on antigorite superperiodicity (T shift of ~20 [degrees]C from 36 to 49 [Angstrom] modulation wavelength). A sharp exothermic peak occurs at extremely constant temperatures (~820 [degrees]C), independently from the starting serpentine structure. The high-T mineral assemblage is always represented by forsterite and enstatite. Based on the observed relationships between serpentine structures and DTG/DTA dehydroxylation temperatures, thermal analysis may represent a useful tool for serpentine identification, particularly in the case of natural massive samples where different varieties are mutually intermixed. The accurate definition of serpentine mineralogy would have obvious implications in both geological-petrological and health-related issues. Keywords: Serpentine, lizardite, antigorite, dehydroxylation, thermal analysis DOI: 10.2138/am.2010.3366 more...
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- 2010
12. Long-term thermal two- and three-dimensional analysis of roller compacted concrete dams supported by monitoring verification
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Kuzmanovic, Vladan, Savic, Ljubodrag, and Stefanakos, John
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Concrete dams -- Mechanical properties -- Thermal properties -- Testing ,Thermal analysis -- Methods ,Structural analysis (Engineering) -- Methods ,Engineering and manufacturing industries - Abstract
This paper presents two-dimensional (2D) and three-dimensional (3D) numerical models for unsteady phased thermal analysis of RCC dams. The time evolution of a thermal field has been modeled using the actual dam shape, RCC technology and the adequate description of material properties. Model calibration and verification has been done based on the field investigations of the Platanovryssi dam, the highest RCC dam in Europe. The results of a long-term thermal analysis, with actual initial and boundary conditions, have shown a good agreement with the observed temperatures. The influence of relevant parameters on the thermal field of RCC dams has been analyzed. It is concluded that the 2D model is appropriate for the thermal phased analysis, and that the boundary conditions and the mixture properties are the most influential on the RCC dam thermal behavior. Key words: 2D and 3D numerical model, unsteady, phased, nonlinear thermal analysis, RCC dam. Cei article presente des modeles numeriques bidimensionnels el tridimensionnels servant a 1'analyse thermique progressive et a I'etat instable des barrages en beton compacte au rouleau (BCR). L'evotution dans le temps d'un champ geothermique a ete modelisee en utilisant la forme reelle du barrage, la technologie BCR et une description adequate des proprietes des materiaux. Le modele a ete etalonne et verifie en se basant sur des essais sur le terrain in situ du barrage Platanovryssi, le plus eleve des barrages BCR en Europe. Les resultats de 1'analyse thermique a long terme, en tenant compte des conditions initiales et limites reelles, correspondent bien aux temperatures observees. L'influence des parametres pertinents sur le champ geothermique des barrages BCR a ete analysee. Le modele bidimensionnel s'est revele approprie pour 1'analyse thermique progressive; les conditions limites ainsi que les proprietes du melange onl le plus d'influence sur le comportement thermique du barrage BCR. Mots-des: modele numerique bidimensionnel et tridimensionnel, instable, progressive, analyse thermique non lineaire, ban-age BCR., 1. Introduction More than 300 roller compacted concrete (RCC) dams have been built around the world in the last 30 years. Two main advantages of RCC dams over the conventional [...] more...
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- 2010
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13. Handling the temperature effect in vibration monitoring: two subspace-based analytical approaches
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Basseville, Michele, Bourquin, Frederic, Mevel, Laurent, Nasser, Houssein, and Treyssede, Fabien
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Vibration tests -- Methods ,Thermal analysis -- Methods ,Structural analysis (Engineering) -- Methods ,Structural analysis (Engineering) -- Technology application ,Technology application ,Science and technology - Abstract
The dynamics of most civil engineering structures is affected by the ambient temperature. This raises the issue of discriminating changes in modal parameters due to damage from those due to such effects. A statistical parametric damage detection algorithm based on a null space residual associated with output-only subspace identification and a [chi square] test built on that residual has been designed by some of the writers. The purpose of this paper is to propose two extensions of this detection method which account for the temperature effect. The first extension uses a thermal model for deriving a temperature-adjusted null space. The second extension exploits the thermal model together with a statistical nuisance rejection technique. Both methods are illustrated on a laboratory test case within a climatic chamber. DOI: 10.1061/(ASCE)0733-9399(2010)136:3(367) CE Database subject headings: Vibration; Damage; Assessment; Temperature effects; Analytical techniques; Structural dynamics. more...
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- 2010
14. Optimization of a weld overlay on a plate structure
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Goldak, John, Asadi, Mahyar, Zhou, Jianguo, Tchernov, Stanislav, and Downey, Dan
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Mathematical optimization -- Research ,Welding -- Research ,Hydraulic turbines -- Mechanical properties ,Hydraulic turbines -- Thermal properties ,Hydraulic turbines -- Testing ,Hydraulic turbines -- Maintenance and repair ,Thermal analysis -- Methods ,Thermal analysis -- Technology application ,Stress analysis (Engineering) -- Methods ,Stress analysis (Engineering) -- Technology application ,Technology application ,Engineering and manufacturing industries - Abstract
An overlay well repair procedure on a 1066.8 x 1066.8 [mm.sup.2] square plate 25.4 mm thick was simulated to compute the 3D transient temperature, microstructure, strain, stress, and displacement of the overlay well repair procedure. The application for the overlay was the repair of cavitation erosion damage on a large Francis turbine used in a hydroelectric project. The overlay well consisted of a 4 x 6 pattern of 100 x 100 [mm.sup.2] squares. Each square Was covered by 15 weld passes. Each well pass was 100 mm long. The total length of weld in the six squares was 36 m. The welds in each square were oriented either front-to-back or left-to-right. The welding process was shielded metal arc. The analysis shows that alternating the welding direction in each square produces the least distortion. A delay time of 950 s between the end of one well pass and the start of the next weld pass was imposed to meet the requirement of a maximum interpass temperature to 50[degrees]C. [DOI: 10.1115/1.4000511] more...
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- 2010
15. On the behavior of misaligned journal bearings based on mass-conservative thermohydrodynamic analysis
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Jang, J.Y. and Khonsari, M.M.
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Journal bearings -- Mechanical properties ,Journal bearings -- Maintenance and repair ,Journal bearings -- Thermal properties ,Thermal analysis -- Methods ,Hydrodynamics -- Analysis ,Hydrofoil boats -- Hydrodynamics ,Hydrofoil boats -- Analysis ,Science and technology - Abstract
Misalignment affects nearly all the bearing performance parameters including the cavitation, thermal field, leakage flow-rate, and moments. The present paper provides a comprehensive analysis of misaligned journal bearings based on a three-dimensional mass-conservative thermohydrodynamic model that appropriately takes into account the film rupture and reformation. An extensive set of numerical solutions are presented to closely examine the effects of misalignment in journal bearings. [DOI: 10.1115/1.4000280] Keywords: misalignment, thermohydrodynamic analysis, mass-conservative, cavitation more...
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- 2010
16. Semianalytical thermal analysis of the heat capacity of YAG laser rods
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Shi, Peng, Bai, Bing, Zhang, Linli, Li, Long, and Xin, Yu
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Thermal analysis -- Methods ,Lasers -- Materials ,Lasers -- Properties ,Lasers -- Testing ,Laser ,Astronomy ,Physics - Abstract
Based on the theory of semianalytical thermal analysis, we investigate the heat capacity of Nd:YAG laser rods for pumping and cooling. A general expression for the temperature field within Nd:YAG laser rod crystals is obtained for the pumping stage and the relation of the maximum temperature rise with pumping time. We also achieve an expression for the temperature field for the cooling stage and the relation of the maximum temperature rise with cooling time. These results show that, when using the output power of 300 W LD pumped Nd:YAG laser rod crystals for 5 s, the maximum temperature rise in the center of the pump face is 154.79[degrees]C. After we stop the pumping for 30 s, the maximum temperature rise drops to 0.8%. These results are in agreement with those reported by others. Our results provide a theoretical basis for the optimized design of a LD end-pumped heat capacity laser. OCIS codes: 120.6810, 140.3480, 140.3580, 160.3380, 140.3320. more...
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- 2009
17. Mechanisms of acute angle laser drilling induced thermal barrier coating delamination
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Sezer, H.K. and Li, L.
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Aircraft engines -- Research ,Thermal analysis -- Methods ,Protective coatings -- Properties ,Thermal stresses -- Research ,Engineering and manufacturing industries ,Science and technology - Abstract
Laser fabrication of cooling holes in certain parts of the aero-engine components involves percussion or trepan drilling at acute angles (e.g., 16-30 deg) to the surface. These parts are often covered with plasma sprayed ceramic thermal barrier coatings (TBCs) to protect them from reaching excessive temperatures in hot engine environments. Delamination of the TBC is the main problem of laser drilling acute angled holes in the coated components. The present study investigates the mechanisms involved in the development of the delamination cracks. A significant role of melt ejection in the formation of cracks and the delamination at the coating/coating interface of the leading edge of a laser-drilled inclined hole was identified. It is shown that the delamination mechanisms at the TBC coating/bond coating and the bond coating/substrate interfaces are different. Melt ejection induced stresses were identified as the key mechanisms for the former type, while the thermal effects dominates the latter type. [DOI: 10.1115/1.4000102] Keywords: laser drilling, thermal barrier coating, delamination more...
- Published
- 2009
18. Crack propagation in glass by laser irradiation along laser scribed line
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Yamamoto, Koji, Hasaka, Noboru, Morita, Hideki, and Ohmura, Etsuji
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Ablation (Vaporization technology) -- Methods ,Stress analysis (Engineering) -- Methods ,Thermal analysis -- Methods ,Glass -- Properties ,Engineering and manufacturing industries ,Science and technology - Abstract
A mechanical breaking process after laser scribing is indispensable to complete the separation of glass substrate since the crack depth induced by the laser scribing is limited. Laser irradiation along the laser scribed line is introduced in this paper as a crack propagation method in depth direction after the laser scribing of a relatively thick glass in order to make the mechanical breaking easier. Since the separating load decreases by propagating the scribed crack deeply, it contributes to the inhibition of glass particle generation. The target of this research is to clarify the mechanism of crack propagation by the laser irradiation along the laser scribed line. Two-dimensional thermal elasticity analysis was conducted by a finite element method based on the experimental results in order to theoretically estimate the laser irradiation condition, which propagates crack. The following results were obtained. Compressive stress is generated on the glass surface and tensile stress is generated inside the glass by the laser irradiation along the laser scribed line. The tensile stress concentrates at the crack tip induced by the laser scribing, and the crack propagates into the depth direction. The condition of crack propagation can be estimated from the maximum surface temperature and the maximum tensile stress of the crack tip in practical processing velocity (200 mm/s or more mm/s). [DOI: 10.1115/1.3207739] Keywords: laser scribing, glass, crack propagation, thermal stress, finite elements method more...
- Published
- 2009
19. Thermal buckling analysis of SMA fiber-reinforced composite plates using layerwise model
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Kumar, S.K. and Singh, B.N.
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Fibrous composites -- Thermal properties ,Fibrous composites -- Mechanical properties ,Thermal analysis -- Methods ,Stress analysis (Engineering) -- Methods ,Plates (Engineering) -- Thermal properties ,Plates (Engineering) -- Materials ,Plates (Engineering) -- Mechanical properties ,Aerospace and defense industries ,Engineering and manufacturing industries ,Science and technology - Abstract
Thermal buckling analysis of laminated smart composite plates subjected to uniform temperature distribution has been presented. Shape memory alloy (SMA) fibers whose material properties depend on temperature have been used as a smart material. A three-dimensional layerwise plate model has been employed in developing the system equations using variational approach. Finiteelement method has been adopted for discretization of the laminate. Lagrangian interpolation functions have been used to approximate the displacement components along the thickness as well as in the in-plane direction. The actual variation of prebuckling stresses has been accounted for in the derivation of the geometric stiffness matrix of the laminates. An incremental load technique has been used in the analysis to take into account the nonlinearity in the material properties of the SMA arising due to their temperature dependence. The effects of thickness ratio, orthotropic ratio, fiber orientation, aspect ratio, stacking sequence and various boundary conditions on the critical buckling temperature have been examined in details. The results have been validated with those available in the literature. DOI: 10.1061/(ASCE)0893-1321 (2009)22:4(342) CE Database subject headings: Fiber reinforced materials; Incremental loads; Buckling; Finite element method; Thermal factors; Plates; Aerospace engineering. more...
- Published
- 2009
20. Thermal removal of mercury in spent powdered activated carbon from TOXECON process
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Okwadha, George D.O., Li, Jin, Ramme, Bruce, Kollakowsky, Dave, and Michaud, Dave
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Hazardous wastes -- Waste management ,Hazardous wastes -- Methods ,Mercury -- Health aspects ,Mercury -- Thermal properties ,Carbon, Activated -- Composition ,Thermal analysis -- Methods ,Thermal analysis -- Usage ,Powders -- Thermal properties ,Powders -- Chemical properties ,Engineering and manufacturing industries ,Environmental issues - Abstract
This research developed and demonstrated a technology to liberate Hg adsorbed onto powdered activated carbon (PAC) by the TOXECON process using pilot-scale high temperature air slide (HTAS) and bench-scale thermogravimetric analyzer (TGA). The HTAS removed 65, 83, and 92% of Hg captured with PAC when ran at 900[degrees]F, 1,000[degrees]F, and 1,200[degrees]F, respectively, while the TGA removed 46 and 100% of Hg at 800[degrees]F and 900[degrees]F, respectively. However, addition of CuO-[Fe.sub.2][O.sub.3] mixture and CuCl catalysts enhanced Hg removal and PAC regeneration at lower temperatures. CuO-[Fe.sub.2][O.sub.3] mixture performed better than CuCl in PAC regeneration. Scanning electron microscopy images and energy dispersive X-ray analysis show no change in PAC particle aggregation or chemical composition. Thermally treated sorbents had higher surface area and pore volume than the untreated samples indicating regeneration. The optimum temperature for PAC regeneration in the HTAS was 1,000[degrees]F. At this temperature, the regenerated sorbent had sufficient adsorption capacity similar to its virgin counterpart at 33.9% loss on ignition. Consequently, the regenerated PAC may be recycled back into the system by blending it with virgin PAC. DOI: 10.1061/(ASCE)EE.1943-7870.0000074 CE Database subject headings: Activated carbon; Mercury; Metals, chemical; Adsorption; Abatement and removal; Thermal factors. more...
- Published
- 2009
21. Thermal probe based analytical microscopy: thermal analysis and photothermal Fourier-transform infrared microspectroscopy together with thermally assisted nanosampling coupled with capillary electrophoresis
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Dai, Xuan, Moffat, Jonathan G., Mayes, Andrew G., Reading, Mike, Craig, Duncan Q.M., Belton, Peter S., and Grandy, David B.
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Scanning microscopy -- Methods ,Thermal analysis -- Methods ,Fourier transform infrared spectroscopy -- Methods ,Microspectroscopy -- Methods ,Electrophoresis -- Methods ,Chemistry - Abstract
In this study, we have demonstrated that a scanning probe microscope (SPM) can be used for thermally assisted nanosampling (TAN) with subsequent analysis by capillary electrophoresis (CE). Localized thermomechanical analysis (L-TMA) and photothermal Fourier-transform infrared (PT-FTIR) microspectroseopy can also be employed using the same probe, thus illustrating how a single instrument can carry out a number of different complementary analytical measurements. Benzoic acid and 4-hydroxy-benzoic acid were manipulated with a heated Wollaston wire probe and successfully deposited onto the surface of a piece of CE capillary tubing. The deposited samples were then separated with CE. L-TMA and PT-FTIR were also used to characterize these materials. We have also demonstrated how a nanosample of a nonparticulate material can be taken and then deposited onto the surface of an inert matrix. TAN of a nonparticulate material was explored using polyethylene as the analyte and fluorene as the matrix. These examples show that thermal probe techniques provide a versatile 'tool box' of modes of analysis with the potential to analyze a wide range of samples in a spatially resolved way. more...
- Published
- 2009
22. High-accuracy thermal analysis methodology for semiconductor junction temperatures by considering line patterns of three-dimensional modules
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Kumano, Yutaka, Ogura, Tetsuyoshi, and Yamada, Toru
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Semiconductors -- Thermal properties ,Thermal analysis -- Methods ,Electronics - Abstract
A novel computational fluid dynamics analysis method of predicting semiconductor junction temperatures precisely without modeling printed circuit board (PCB) line patterns was developed. First, PCBs are divided into multiple regions. The effective anisotropic thermal conductivity of each region is then assigned as follows. All the regions are divided into smaller subregions whose size is below the pattern width. The thermal conductivity of each subregion is defined by the property of the material at the center of the subregion. Next, a thermal circuit network composed of all the subregions is generated, and finally the anisotropic thermal conductivities of each region are computed by solving this thermal network matrix. When boards' are divided into multiple regions, there is a convergence region size under which the analytical results show no further change. In this paper, the relationship between the size of the divided regions and the accuracy of the analytical results was investigated. It was confirmed that the calculated semiconductor junction temperatures were precisely coincident with the experimental results when the size of the regions was less than 20 times the line pattern width. [DO]: 10.1115/1.3103947] Keywords: 3D module, PCB, pattern, trace, semiconductor, junction temperature, CFD, CAD more...
- Published
- 2009
23. Ion attachment mass spectrometry combined with infrared image furnace for thermal analysis: evolved gas analysis studies
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Kitahara, Yuki, Takahashi, Seiji, Kuramoto, Noriyuki, Sala, Martin, Tsugoshi, Takahisa, Sablier, Michel, and Fujii, Toshihiro
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Ions -- Properties ,Ions -- Usage ,Mass spectrometry -- Methods ,Infrared imaging -- Methods ,Thermal analysis -- Methods ,Pyrolysis -- Research ,Atmospheric pressure -- Observations ,Atmospheric gases -- Properties ,Atmospheric gases -- Composition ,Trace analysis -- Methods ,Chemistry - Abstract
A well-established ion attachment mass spectrometer (IAMS) is combined with an in-house single-atom infrared image furnace (IIF) specifically for thermal analysis studies. Besides the detection of many chemical species at atmospheric pressure, including free radical intermediates, the ion attachment mass spectrometer can also be used for the analysis of products emanating from temperature-programmed pyrolysis. The performance and applicability of the IIF-IAMS is illustrated with poly(tetrafluoroethylene) (PTFE) samples. The potential of the system for the analysis of oxidative pyrolysis is also considered. Temperature-programmed decomposition of PTFE gave constant slopes of the plots of temperature versus signal intensity in a defined region and provided an apparent activation energy of 28.8 kcal/mol for the PTFE decomposition product [([CF.sub.2]).sub.3]. A brief comparison with a conventional pyrolysis gas chromatography/ mass spectrometry system is also given. more...
- Published
- 2009
24. Compact thermal models: a global approach
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Sabry, Mohamed-Nabil and Abdelmeguid, Hossam Saleh
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Thermal analysis -- Methods ,Engineering models -- Usage ,Electronics - Abstract
The construction and usage of compact thermal models (CTMs), for the thermal analysis as well as the design of cooling devices for electronic systems, are reviewed. These models have many advantages over the so called detailed models based on 3D simulations, mainly being a convenient and simple quantitative description of the modeled object, when constructional details are either unavailable or too detailed to be of use at the desired level of analysis. However, CTMs have manifested some deficiencies in many cases, in particular, multiple chip modules (MCM) and stacked dies. The opposite approach, detailed modeling, is more reliable, although extremely heavy. A new approach is proposed that solves this dilemma by bridging the gap between compact and detailed models. While retaining all advantages of CTMs, i.e., having a limited number of degrees of freedom and not requiring detailed constructional features, it can attain any required precision level depending on the degree of complexity adopted. It gives reliable results covering all operating conditions including MCM and stacked dies. Moreover, it gives access to data on surface temperature gradients that were never obtained before by compact models and are highly important for reliability issues. [DOI: 10.1115/1.2993132] more...
- Published
- 2008
25. Crystal chemistry of macfallite: Relationships to sursassite and pumpellyite
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Nagashima, Mariko, Rahmoun, Nouri-Said, Alekseev, Evgeny V., Geiger, Charles A., Armbruster, Thomas, and Akasaka, Masahide
- Subjects
Fourier transform infrared spectroscopy -- Methods ,Silicates -- Thermal properties ,Silicates -- Chemical properties ,Thermal analysis -- Methods ,Crystals -- Structure ,Crystals -- Evaluation ,Earth sciences - Abstract
The crystal chemistry of macfallite from Keweenaw County, Michigan was studied using electron microprobe, thermogravimetry (TG), differential thermal analysis (DTA), powder Fourier transform infrared (FTIR) spectroscopy, and single-crystal X-ray diffraction methods The chemical formula derived from the electron-microprobe measurements is [([Ca.sub.2.03][Na.sub.0.01].sub.[SIGMA]2.04][([Mn.sup.3+.sub.2.51] [Al.sub.0.27][Mg.sub.0.09][Cu.sup.2+.sub.0.03][V.sup.3+.sub.0.01]).sub. [[SIGMA].sub.2.91][Si.sub.3.05][O.sub.10.88][(OH).sub.3.12] (Z = 2). An analysis using the intensities of the MnL[beta] and MnL[alpha] X-ray lines shows that most Mn is trivalent. The weight loss from TG measurement is 7.7 wt% at 1000[degrees]C, most of which is interpreted to be due to the loss of structural OH groups. The crystal structure of macfallite [a = 8.959(3), b = 6.072(2), c = 10.218(4) [Angstrom], [beta] = 110.75(3)[omicron], space group [P2.sub.1]/m], which is isostructural with sursassite, was refined using 1717 unique reflections to R = 4.1%. The site populations at the three independent octahedral sites, Mn1, Mn2, and Mn3, are [Mn.sub.0.82][Al.sub.0.06][Mg.sub.0.09][Cu.sub.0.03], [Mn.sub.0.75][Al.sub.0.25], and [Mn.sub.0.95][Al.sub.0.05], respectively. In agreement with a bond-valence analysis, three crystal-chemically different OH groups are located at the O6, O10, and O11 positions. The site O7 is mostly occupied by oxygen, but minor amounts of hydroxyl may be located there as well. The powder FTIR spectrum in the region of the OH-stretching vibrations is characterized by three strong bands at 3413, 3376, and 3239 [cm.sup.-1] and an additional broad absorption band around 2900 [cm.sup.-1] The latter results from a relatively strong hydrogen bond, O6-H [??] O11, with a length of ~2.63 [Angstrom]. Although there are three main hydroxyl groups occurring in macfallite, the exact number depends on the concentration of trivalent and divalent cations at the Mn1 site. If divalent cations occur at Mn1, a fourth OH group is necessary to maintain charge balance. Keywords: Macfallite, pumpellyite, sursassite, Mn silicates, hydrous silicates, FTIR spectroscopy, crystal structure more...
- Published
- 2008
26. Design of axial flux PM synchronous machines through 3-D coupled electromagnetic thermal and fluid-dynamical finite-element analysis
- Author
-
Marignetti, Fabrizio, Delli Colli, Vincenzo, and Coia, Yuri
- Subjects
Fluid dynamics -- Research ,Magnets, Permanent -- Properties ,Thermal analysis -- Methods ,Finite element method -- Usage ,Business ,Computers ,Electronics ,Electronics and electrical industries - Abstract
This paper investigates the thermal behavior of axial flux synchronous permanent-magnet machines (AFSPMMs) through a 3-D thermal-magnetic finite-element analysis (FEA). This paper offers a systematic approach to magnetothermal FEA. The considered axial flux machine is wound on a soft magnetic compound core. The computation of thermal field is performed via a coupled thermal and fluid-dynamical model based on FEA, where the thermal sources are obtained from a dc current flow model and a magnetostatic model. This paper includes an overview of the finite-element method (FEM) model implementation. Simulation results are presented, and, to validate the model, the simulated surface temperature rise of the motor parts is compared by experimental data. Index Terms--Axial flux machines, electrical machines, finite-element analysis (FEA), finite-element method (FEM), fluid dynamics, thermal analysis. more...
- Published
- 2008
27. A coupled thermal-electromagnetic analysis for a rapid and accurate prediction of IM performance
- Author
-
Alberti, Luigi and Bianchi, Nicola
- Subjects
Thermal analysis -- Methods ,Finite element method -- Usage ,Induction electric motors -- Design and construction ,Business ,Computers ,Electronics ,Electronics and electrical industries - Abstract
The design of electrical machines for extreme operating conditions must include a thermal analysis coupled with the magnetic analysis. However, the traditional coupling of the thermal and the magnetic models can result in an unacceptable increase in computation time, particularly if finite elements (FEs) are used for the machine analysis. This paper proposes a coupled thermal-magnetic analysis of an induction motor (IM) with the primary goal of achieving a rapid and accurate prediction of the IM performance. Only a minimum set of FE magnetic analyses is carried out so as to determine the parameters of the IM equivalent circuit. These parameters are nonlinear and are adjusted on the basis of the operating point. Then, this equivalent circuit is coupled with a lumped-parameter thermal network to predict the temperature in each part of the IM. Since both the equivalent circuit and thermal network solutions are analytic, the analysis converges very rapidly. At the same time, the FE analysis yields a precise estimation of the IM parameters used in the equivalent circuit. Some experimental results are reported, showing the accurate prediction of the proposed methodology. Index Terms--AC motor drives, finite-element (FE) analysis, induction motors (IMs), performance prediction, thermal analysis. more...
- Published
- 2008
28. Thermal analysis of radial-flux electrical machines with a high power density
- Author
-
Nerg, Janne, Rilla, Marko, and Pyrhonen, Juha
- Subjects
Thermal analysis -- Methods ,Industrial electronics -- Research ,Electrical equipment and supplies -- Thermal properties ,Electrical equipment and supplies -- Design and construction ,Electrical machinery -- Thermal properties ,Electrical machinery -- Design and construction ,Business ,Computers ,Electronics ,Electronics and electrical industries - Abstract
A lumped-parameter-based thermal analysis applicable to radial-flux electrical machines with a high power density is presented. The modeling strategies using T-equivalent lumped-parameter blocks as well as conventionally defined thermal resistances are discussed. Special attention is paid to the modeling of the convective heat transfer in the air gap of radial-flux electrical machines at different rotational speeds. A brief overview of the evaluation of different loss components is given. The performance of the developed thermal model was verified by comparing the calculated temperature values with the measurements in three different applications. Index Terms--Electrical machines, loss modeling, thermal analysis, thermal resistance network. more...
- Published
- 2008
29. Reduced thermal model of an induction machine for real-time thermal monitoring
- Author
-
Jaljal, Nawal, Trigeol, Jean-Francois, and Lagonotte, Patrick
- Subjects
Real-time control -- Design and construction ,Real-time systems -- Design and construction ,Electrical equipment and supplies -- Design and construction ,Electrical equipment and supplies -- Control ,Electrical machinery -- Design and construction ,Electrical machinery -- Control ,Thermal analysis -- Methods ,Industrial electronics -- Research ,Real-time system ,Business ,Computers ,Electronics ,Electronics and electrical industries - Abstract
An electric machine submitted to dissipations and a too high temperature can generate irreversible damage. A reduced thermal model allows us to monitor the critical points of the machine. The thermal modeling of the machine adopted here results from the association of two methods: a nodal approach which models the diffusion in the structure and a computational fluid dynamics (CFD) approach which characterizes the convective heat exchanges which operate in the end cavities. A methodology of reduction is proposed and applied to the thermal model of a 5.5-kW two-pole induction machine to obtain a reduced four-node model for real-time thermal monitoring. Index Terms--Electric machines, identification, model reduction, thermal modeling. more...
- Published
- 2008
30. Combined thermal and electromagnetic analysis of permanent-magnet and induction machines to aid calculation
- Author
-
Dorrell, David G.
- Subjects
Thermal analysis -- Methods ,Induction electric motors -- Design and construction ,Industrial electronics -- Research ,Magnets, Permanent -- Properties ,Business ,Computers ,Electronics ,Electronics and electrical industries - Abstract
This paper reports on methods for the analysis of electrical machines by combined electromagnetic and thermal models using commercial software which can be an aid to the design of these machines. Examples using a brushless permanent-magnet motor and an induction motor illustrate the available tools and possible techniques. It reviews the different loss calculations, particularly iron losses, and also the thermal models that can be used, including steady state and transient (where thermal capacitances have to be included). This paper will be useful to an engineer in an industrial design office to illustrate the possibilities that are now possible. Index Terms--Electromagnetic design, losses, motors, thermal analysis. more...
- Published
- 2008
31. Crystal chemistry of the mixed-layer sequence talc-talc-smectite-smectite from submarine hydrothermal vents
- Author
-
Cuadros, Javier, Dekov, Vesselin M., and Fiore, Saverio
- Subjects
Infrared spectroscopy -- Methods ,Mineralogical chemistry -- Research ,Smectite -- Composition ,Smectite -- Thermal properties ,Talc -- Composition ,Talc -- Thermal properties ,Thermal analysis -- Methods ,X-rays -- Diffraction ,X-rays -- Methods ,Earth sciences - Abstract
Clay samples of hydrothermal origin from several oceanic spreading centers were studied using XRD, microprobe, infrared, and thermal analysis. They are talc, smectite, and mixed-layer talc-smectite (T-S) where the talc layers have several degrees of crystalline order. The smectite is trioctahedral in most cases, but there is also dioctahedral smectite both as mixed-layer and as a separate phase. All specimens contain [Fe.sup.3+], some of them in moderate amounts (up to 17% [Fe.sub.2][O.sub.3]) distributed between the tetrahedral and octahedral sheets (maximum values: [sup.IV]Fe = 0.32, [sup.VI]Fe = 0.68, per [O.sub.10][[OH].sub.2]). Octahedral Fe abundance correlates with the presence of molecular water that is lost in a well-defined dehydration event above 200[degrees]C. This water does not cause layer expansion and is interpreted to be present within the pseudo-hexagonal cavity, next to [Fe.sup.3+] ions that generate a local charge imbalance. The presence of octahedral [Fe.sup.3+] is accompanied by vacancies in the octahedral sheet to balance the excess positive charge. Ah infrared band at ~790 [cm.sup.-1] is assigned to OH bending in the group Fe-Mg-[]-OH. Analysis of this band suggests a range of short-range Fe-[] distributions, from random to ordered. Our sequence tale, T-S, trioctahedral smectite is defined by an increasing Al for Si substitution in the tetrahedra and increasing crystal disorder. The presence of Fe also causes crystal defects. This mixed-layer series can be considered as a continuum generated by the combination of chemical and crystal defect variability. Kerolite was used to designate disordered, hydrated talc. We find that there is no clear line delimiting talc from kerolite as a single phase or in mixed-layer minerals and that it is better to use a descriptive term for the latter such as 'disordered talc.' Dioctahedral smectite is also a possible end-member of the mixed-layer sequence, which implies an Al + [] for Mg substitution in the octahedral sheet. If T-S consists of polar TOT layers, the existence of dioctahedral smectite in T-S raises the question of the actual composition of the octahedral sheets within polar TOT layers. Keywords: Crystal chemistry, infrared spectroscopy, kerolite, talc, talc-smectite, thermal analysis, trioctahedral smectite, X-ray diffraction more...
- Published
- 2008
32. Thermogravimetry coupled to single photon ionization quadrupole mass spectrometry: a tool to investigate the chemical signature of thermal decomposition of polymeric materials
- Author
-
Saraji-Bozorgzad, M., Geissler, R., Streibel, T., Muhlberger, F., Sklorz, M., Kaisersberger, E., Denner, T., and Zimmermann, R.
- Subjects
Thermal analysis -- Methods ,Polymers -- Chemical properties ,Polymers -- Thermal properties ,Mass spectrometry -- Methods ,Chemistry - Abstract
Mass spectrometry (MS) is an established analytical technique to analyze evolved gas in thermogravimetry (TG). In this study, for the first time a novel SPI-MS technique using an electron beam pumped VUV excimer lamp as photon source ([lambda] = 126 nm) was employed in conjunction with thermogravimetry. The coupling was achieved with an improved heated interface and adjacent transfer capillary between TG and ion source of a quadrupole mass spectrometer. The feasibility of this approach was proven by investigating semivolatile substances such as long-chain alkanes (heptadecane [C.sub.17][H.sub.36]), polymers, e.g., polystyrene, polycarbonate, and acrylonitrile--butadiene--styrene, polymer mixtures and blends. Mass spectra with almost no fragmentation were obtained, and quantification of selected substances could be achieved. Polymer mixtures could be distinguished by their SPI mass spectra, and the effect of premixing of polymers has been accessed. Its unique attributes render the TA-SPIMS method a promising new tool for quantitative and qualitative evaluation of complex organic thermal degradation products. more...
- Published
- 2008
33. Point mutation detection by surface plasmon resonance imaging coupled with a temperature scan method in a model system
- Author
-
Fiche, J.B., Fuchs, J., Buhot, A., Calemczuk, R., and Livache, T.
- Subjects
Gene mutations -- Research ,Imaging systems -- Methods ,Thermal analysis -- Methods ,Chemistry - Abstract
The detection of point mutations in genes presents clear biological and medical interest. Various methods have been considered. In this paper, we take advantage of surface plasmon resonance imaging, a technique allowing detection of unlabeled DNA hybridization. Coupled with a temperature scan, this approach allows us to determine the presence of single-point mutations in oligonucleotide samples from the analysis of DNA's melting curves in either the homozygous or heterozygous case. Moreover, these experimental data are confirmed in good agreement with numerical calculations. more...
- Published
- 2008
34. Application of thermal analysis to elucidate water-repeilency changes in heated soils
- Author
-
Dlapa, Pavel, Simkovic, Ivan, Jr., Doerr, Stefan H., Simkovic, Ivan, Kanka, Robert, and Mataix-Solera, Jorge
- Subjects
Soil mechanics -- Research ,Thermal analysis -- Methods ,Wildfires -- Research ,Soil moisture -- Research ,Humus -- Thermal properties ,Humus -- Chemical properties ,Earth sciences - Abstract
It is well established that during wildfires, the volatilization and condensation of hydrophobic compounds, as well as the thermal energy input itself, can markedly change the wettability of soils. This study evaluated the effects of thermal energy input on soil water repellency of sandy forest soils from Slovakia and explored the processes underlying the changes observed using thermal analysis. Initial sample water drop penetration time values ranged from 43,200 s. Heating induced distinct increases in water repellency to >3600 s in most samples, with its elimination occurring at 175[degrees]C or higher. The thermal analysis allowed evaluation of the relationship between the destruction of soil water repellency and thermal changes affecting soil organic matter (SOM). Differences in the thermal resistance of soil water repellency correspond to the thermal stability of SOM. Kinetic analysis showed that water repellency elimination due to soil heating is linked with thermal decomposition of a more thermally labile pool of SOM. The results suggest that under nonisothermal conditions, the degree of SOM decomposition depends on both the soil temperature reached and the soil heating rate. The temperature at which a certain level of SOM decomposition is reached increases with increasing heating rate. Heating experiments and the kinetic evaluation of thermogravimetric data for isothermal conditions also demonstrated an exponential relationship between heating durations and temperature thresholds. Abbreviations: DTA, differential thermal analysis; DTG, derivative thermogravimetric analysis; SOM, soil organic matter; TGA, thermogravimetric analysis; WDPT, water drop penetration time. more...
- Published
- 2008
35. Semianalytical thermal analysis of thermal focal length on Nd:YAG rods
- Author
-
Shi, Peng, Chen, Wen, Li, Long, and Gan, Ansheng
- Subjects
Thermal analysis -- Methods ,Garnet -- Thermal properties ,Garnet -- Optical properties ,Astronomy ,Physics - Abstract
Based on the theory of semianalytical thermal analysis, the temperature field and thermal lens effects within a diode-end-pumped Nd:YAG rods were investigated. A general expression of the temperature field within Nd:YAG rods was obtained through the analysis of a diode-end-pumped Nd:YAG rod, using what we believe to be a new method to solve a heat conduction equation ofisotropic material. Calculating the thermal focal length within the diode-end-pumped Nd:YAG rods was done by an analysis of the additional optical path differences caused by heat, which was in good agreement with experimental results. These results show that the maximum temperature on the pump face of Nd:YAG rods is 51.9 [degrees]C and the thermal focal length is 22.4 cm when the output power of the diode laser is 10 W. Under the same conditions, the experimental value of the thermal focal length is 21.0 cm. The difference between the theoretical analysis and the experimental result is only 6.7%. Results from this work can provide the theoretical basis for the optimized design of diode-end-pumped all-solid-state lasers. OCIS codes: 120.6810, 140.3480, 140.3580. more...
- Published
- 2007
36. Permian-Triassic high thermal regime in the Alps: result of late Variscan collapse or continental rifting? Validation by numerical modeling
- Author
-
Marotta, Anna Maria and Spalla, Maria Iole
- Subjects
Alps -- Natural history ,Finite element method -- Usage ,Thermal analysis -- Methods ,Earth sciences - Abstract
The Permian-Triassic igneous activity, associated with regional scale deformation developed under high-temperature/low-pressure (HT-LP) metamorphic conditions and widely recorded in the pre-Alpine crust of the European Alps, can result from late orogenic collapse of a collisional belt or from lithospheric thinning leading to a continental rifting process. In order to reduce this ambiguity, we use a two-dimensional finite element model to give new insights on the sequence of mechanisms operating during active ocean-continent convergence, followed by continental collision and pure gravitational evolution and on the regional geodynamic interpretation of the Paleozoic-Mesozoic evolution of the Alpine area. The modeling predictions are compared with the PT climax conditions of Variscan and Permian-Triassic metamorphism affecting the continental crust of the Helvetic to Southalpine domains. The good agreement between model predictions and natural data realized for the early to Neovariscan evolution indicates that during Paleozoic, the pre-Alpine crust of the Alps was part of an active ocean-continent convergence margin and an intracontinental suture zone. Furthermore, modeling results support the interpretation envisaging a Permian-Triassic lithospheric extension as responsible for the HT metamorphism and related intense igneous activity. This evolution was precursor of the Mesozoic oceanization, during which the tectonic units, coupled and accreted during the Variscan subduction and collision, were separated to form the two passive European and Adriatic continental margins. doi:10.1029/2006TC002047. more...
- Published
- 2007
37. Steady-state thermal simulation of weld applied to a practical axisymmetric weldment
- Author
-
Uchida, Ken, Sumiya, Rie, Murofushi, Tadashi, and Jimbo, Masakazu
- Subjects
Computer-generated environments -- Usage ,Computer simulation -- Usage ,Welded joints -- Mechanical properties ,Welded joints -- Thermal properties ,Thermal analysis -- Methods ,Engineering and manufacturing industries - Abstract
Steady-state Eulerian analysis on thermal simulation of welds using moving coordinates is known as a very computationally efficient method. This paper presents a method of Eulerian analysis that uses commercial computational fluid dynamics code. In order to show the practical availability of the Eulerian method, the method is applied to an analysis of a circumferential weld of a core shroud in a boiling water reactor. In this analysis, the double ellipsoidal power density distribution model proposed by Goldak, Chakravarti, and Bibby (1984, Metall. Trans. B, 15B, pp. 299-305) is applied for the weld heat source, the temperature dependency of thermal properties is considered, and the effect of latent heat is treated by enthalpy method. Comparison of the analyzed temperature histories at several locations on the surface of the weldment to the measured results shows that the numerical results reproduce the measured results well. [DOI: 10.1115/1.2716430] Keywords: weld, thermal analysis, steady state, Eulerian, moving coordinates, CFD code more...
- Published
- 2007
38. Fast thermal simulation for runtime temperature tracking and management
- Author
-
Pu Liu, Hang Li, Lingling Jin, Wei Wu, Tan, Sheldon X.-D., and Jun Yang
- Subjects
Circuit designer ,Integrated circuit design ,Thermal analysis -- Methods ,Power conditioning -- Methods ,Circuit design -- Analysis - Published
- 2006
39. Transient thermal analysis for board-level chip-scale packages subjected to coupled power and thermal cycling test conditions
- Author
-
Wang, Tong Hong, Lee, Chang-Chi, Lai, Yi-Shao, and Lin, Yu-Cheng
- Subjects
Microelectronic packaging -- Methods ,Thermal analysis -- Methods ,Semiconductor device ,Electronics - Abstract
In this work, thermal characteristics of a board-level chip-scale package, subjected to coupled power and thermal cycling test conditions defined by JEDEC, are investigated through the transient thermal analysis. Tabular boundary conditions are utilized to deal with time-varying thermal boundary conditions brought by thermal cycling. It is obvious from the analysis that the presence of power cycling leads to a significant deviation of the junction temperature from the thermal cycling profile. However, for components away from the die, the deviation is insignificant. Moreover, for low-power applications, temperature histories from coupled power and thermal cycling are approximately linear combinations of temperature histories from pure power cycling and the ones from pure thermal cycling. [DOI: 10.1115/1.2229229] Keywords: power cycling, thermal cycling, JEDEC, transient thermal analysis more...
- Published
- 2006
40. Phase transformations in the high-[T.sub.c] superconducting compounds, [Ba.sub.2][RCu.sub.3][O.sub.7-δ] (R = Nd, Sm, Gd, Y, Ho, and Er)
- Author
-
Wong-Ng, W., Cook, L.P., Su, H.B., Vaudin, M.D., Chiang, C.K., Welch, D.R., Fuller, Jr., E.R., Yang, Z., and Bennett, L.H.
- Subjects
Phase transformations (Statistical physics) -- Research ,X-rays -- Diffraction ,Thermal analysis -- Methods ,Superconductors -- Chemical properties -- Composition - Abstract
1. Introduction Recent advances in coated conductor science and engineering have brought commercial high-[T.sub.c] superconductor technology closer to reality (1). It is now likely that many potential large-scale industrial applications […] more...
- Published
- 2006
41. Melting of nanostructured drugs embedded into a ploymeric matrix
- Author
-
Bergese, P., Colombo, I., Gervasoni, D., and Depero, Laura E.
- Subjects
Chemistry, Physical and theoretical -- Research ,Thermal analysis -- Methods ,Chemicals, plastics and rubber industries - Abstract
The melting behavior of nanostructured organic materials (drugs) embedded into a cross-linked polymeric matrix is studied. The complex microstructure of these nanocomposites, yielded by the polymer matrix in which molecular clusters and nanocrystals of drug plus a cospiquous fraction of water are confined, demanded synergic application of thermal analysis and temperature resolved X-ray diffraction. more...
- Published
- 2004
42. Lyophilization: a primer: optimized freeze-drying cycles can offer scientific and business advantages
- Author
-
Scoffin, Katriona and Ciccolini, Laura
- Subjects
Thermal analysis -- Methods ,Freeze-drying -- Methods -- Usage ,Pharmaceutical industry -- Production processes -- Production management -- Quality management -- Standards ,Business ,Pharmaceuticals and cosmetics industries - Abstract
Freeze drying, or lyophilization, is a stabilization method that is widely used in the pharmaceutical industry for drugs, vaccines, antibodies, and other biological material. Because the product is dried without [...] more...
- Published
- 2013
43. Determination of the total oxygen isotopic composition of nitrate and the calibration of a [[DELTA].sup.17]O nitrate reference material
- Author
-
Michalski, Greg, Savarino, Joel, Bohlke, J.K., and Thiemens, Mark
- Subjects
Nitrates ,Thermal analysis -- Methods ,Isotope separation -- Methods ,Programming tutorial ,Chemistry - Abstract
A thermal decomposition method was developed and tested for the simultaneous determination of [[delta].sup.18]O and [[delta].sup.17]O in nitrate. The thermal decomposition of AgN[O.sub.3] allows for the rapid and accurate determination of [sup.18]O/ [sup.16]O and [sup.17]O/[sup.16]O isotopic ratios with a precision of [+ or -] 1.5 [per thousand] for [[delta].sup.18]O and [+ or -] 0.11 [per thousand] for [[DELTA].sup.17]O ([[DELTA].sup.17]O = [[delta].sup.17]O - 0.52 x [[delta].sup.18]O). The international nitrate isotope reference material IAEA-NO3 yielded a [[delta].sup.18]O value of +23.6 [per thousand] and [[DELTA].sup.17]O of -0.2 [per thousand], consistent with normal terrestrial mass-dependent isotopic ratios. In contrast, a large sample of NAN[O.sub.3] from the Atacama Desert, Chile, was found to have [[DELTA].sup.17]O = 21.56 [+ or -] 0.11 [per thousand] and [[delta].sup.18]O = 54.9 [+ or -] 1.5 [per thousand], demonstrating a substantial mass-independent isotopic composition consistent with the proposed atmospheric origin of the desert nitrate. It is suggested that this sample (designated USGS-35) can be used to generate other gases (C[O.sub.2], CO, [N.sub.2]O, [O.sub.2]) with the same [[DELTA].sup.17]O to serve as measurement references for a variety of applications involving mass-independent isotopic compositions in environmental studies. more...
- Published
- 2002
44. Measurement of transfer matrices and source terms of premixed flames
- Author
-
Paschereit, C.O., Schuermans, B., Polifke, W., and Mattson, O.
- Subjects
Gas-turbines -- Combustion chambers ,Thermal analysis -- Methods ,Matrix mechanics -- Research ,Engineering and manufacturing industries ,Science and technology - Abstract
An experimental method to determine the thermoacoustic properties of a gas turbine combustor using a lean-premixed low emission swirl stabilized burner is presented. To model thermoacoustic oscillations, a combustion system can be described as a network of acoustic elements, representing for example fuel and air supply, burner and flame, combustor, cooling channels, suitable terminations, etc. For most of these elements, simple analytical models provide an adequate description of their thermoacoustic properties. However, the complex response of burner and flame (involving a three-dimensional flow field, recirculation zones, flow instabilities, and heat release) to acoustic perturbations has--at least in a first step--to be determined by experiment. In our approach, we describe the burner as an active acoustical two-port, where the state variables pressure and velocity at the inlet and the outlet of the two port are coupled via a four element transfer matrix. This approach is similar to the 'black box' theory in communication engineering. To determine all four transfer matrix coefficients, two test states, which are independent in the state vectors, have to be created. This is achieved by using acoustic excitation by loudspeakers upstream and downstream of the burner, respectively. In addition, the burner might act as an acoustic source, emitting acoustic waves due to an unsteady combustion process. The source characteristics were determined by using a third test state, which again must be independent from the two other state vectors. In application to a full size gas turbine burner, the method's accuracy was tested in a first step without combustion and the results were compared to an analytical model for the burner's acoustic properties. Then the method was used to determine the burner transfer matrix with combustion. An experimental swirl stabilized premixed gas turbine burner was used for this purpose. The treatment of burners as acoustic two-ports with feedback including a source term and the experimental determination of the burner transfer matrix is novel. more...
- Published
- 2002
45. Stable and metastable phase diagram of the two-component system (CH(sub)3)(sub)3--(CH(sub)3)CCl(sub)3: an example of crossed isodimorphism
- Author
-
Pardo, Luis C., Barrio, Maria, Tamarit, Josep LI., Negrier, Philippe, and Lopez, David O.
- Subjects
Chemistry, Physical and theoretical -- Research ,Isomorphism (Crystallography) -- Analysis ,Thermal analysis -- Methods ,Chemicals, plastics and rubber industries - Published
- 2001
46. Stripping Analysis of Nucleic Acids at a Heated Carbon Paste Electrode
- Author
-
Wang, Joseph, Grundler, Peter, Flechsig, Gerd-Uwe, Jasinski, Markus, Rivas, Gustavo, Sahlin, Eskil, and Paz, Luis Lopez
- Subjects
Nucleic acids -- Analysis ,Electrodes, Carbon -- Design and construction ,Electrochemistry -- Research ,Potentiometry -- Methods ,Thermal analysis -- Methods ,Chemistry - Abstract
A new electrically heated carbon paste electrode has been developed for performing adsorptive stripping measurements of trace nucleic acids. Such coupling of electrochemistry at electrically heated electrodes with adsorptive constant-current stripping chronopotentiometry offers distinct advantages for trace measurements of nucleic acids. The application of increased temperatures during the deposition step results in dramatic (4-34-fold, depending on temperature applied) enhancement of the stripping signal. Such improvement is attributed to the accumulation step at the heated electrode. Forced thermal convection near the electrode surface facilitates the use of quiescent solutions and hence of ultrasmall volumes. Using an electrode temperature of 32 degrees C and a quiescent solution during the 1-min accumulation, the response is linear over the 1-8 mg/L range tested, with a detection limit of 0.5 mg/L. Such electrode heating technology offers great promise for various applications involving thermal manipulations of nucleic acids. more...
- Published
- 2000
47. Organic thermochemistry at high ab initio levels. a G3 study of cyclic saturated and unsaturated hydrocarbons (including aromatics), 3
- Author
-
Notario, R., Castano, O., Gomperts, R., Frutos, L.M., and Palmeiro, R.
- Subjects
Organic compounds -- Research ,Chemical systems -- Analysis ,Thermal analysis -- Methods ,Enthalpy -- Measurement ,Biological sciences ,Chemistry - Abstract
Results demonstrate that the application of the G3 methodology, coupled with the atomization reaction method, to the simple cyclic, saturated, unsaturated, and aromatic molecules facilitates determination of standard heats of formation of hydrocarbons. more...
- Published
- 2000
48. THERMAL BALANCE OF ON-STREAM STORM-WATER MANAGEMENT POND
- Author
-
Van Buren, M.A., Watt, W.E., Marsalek, J., and Anderson, B.C.
- Subjects
Storm water retention basins -- Management ,Rain-water (Water-supply) -- Management ,Thermal analysis -- Methods ,Thermodynamics -- Research ,Engineering and manufacturing industries ,Environmental issues - Abstract
A methodology and assessment of the thermal balance of an on-stream storm-water pond are documented for a test facility in Kingston, Ontario, Canada. An energy balance model was used to estimate average pond water temperature as a function of thermal energy stored in the pond. Major thermal energy fluxes considered within the pond system included radiant heating and cooling of the pond, evaporation, and thermal energy inflow from the upstream catchment and outflow from the pond. A thermal energy balance was achieved between thermal energy input and output measured over the field season. During dry-weather periods, pond temperature increased as a result of solar heating, and thermal energy input exceeded output. Conversely, during wet-weather periods, pond temperature decreased as a result of limited solar radiation and replacement of warm pond water by cool inflow water from the upstream catchment, and thermal energy output exceeded input. A series of discrete temperature surveys in the pond revealed that the location of the stationary temperature probe, used to measure pond temperature, resulted in an underestimation of the average pond temperature during dry and wet-weather periods. However, this discrepancy was comparable to the difference between measured and modeled values, which further confirmed the model validity. more...
- Published
- 2000
49. Investigating the effects of oxidation and thermal degradation on electrical and chemical properties of power transformers insulation
- Author
-
Saha, T.K., Darveniza, M., Yao, Z.T., Hill, D.J.T., and Yeung, G.
- Subjects
Electric insulators -- Testing ,Electric transformers -- Design and construction ,Oxidation, Physiological -- Research ,Thermal analysis -- Methods ,Business ,Computers ,Electronics ,Electronics and electrical industries - Abstract
This paper describes the analysis of thermally accelerated aged insulation samples to investigate the degradation processes observed in the insulation of aged transformers. Accelerated ageing experiments were performed on paper wrapped insulated conductors in the presence of air and nitrogen environments over a temperature range of 115 to 145 degrees C. Effects of oxidation on the ageing of oil-paper insulation were investigated and results are presented in this paper. The conditions of aged insulation samples was investigated by a number of diagnostic techniques: (a) measurements of interfacial polarization spectra by the return voltage method (b) measurement of molecular weight and its distribution by gel permeation chromatography, (c) surface analysis by X-ray photo-electron spectroscopy and (c) a study of the oxidation of the oil by a UV-visible spectroscopy. Results from these measurements are presented in this paper and are used to analyse the degradation process with special emphasis on oxidation. Keywords: Transformer insulation, ageing, oil-paper, interfacial polarization spectra, return voltage, gel permeation chromatography, condition monitoring more...
- Published
- 1999
50. Use of solid insertion probe mass spectrometry and constant rate thermal analysis in the study of materials: determination of apparent activation energies and mechanisms of solid-state decomposition reactions
- Author
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Tiernan, M.J., Barnes, P.A., and Parkes, G.M.B.
- Subjects
Carbonates -- Analysis ,Chemical reactions -- Analysis ,Decomposition (Chemistry) -- Analysis ,Spectrum analysis -- Methods ,Thermal analysis -- Methods ,Chemicals, plastics and rubber industries - Abstract
A study describes a solid insertion probe-mass spectrometry (SIP-MS) system using low-mass samples that are heated under high vacuum to provide almost ideal experimental conditions for the measurement of apparent activation energies and the study of mechanisms of solid-state decompositions that produce a gas or gases. This SIP-MS system was used with both linear heating and constant rate thermal analysis methods to investigate the decomposition of sodium hydrogen carbonate and calcium carbonate. Results are discussed. more...
- Published
- 1999
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