Wire Temperature Research Articles

Flutter and Thermal Buckling Analysis for Composite Laminated Panel Embedded with Shape Memory Alloy Wires in Supersonic Flow

The flutter and thermal buckling behavior of laminated composite panels embedded with shape memory alloy (SMA) wires are studied in this research. The classical plate theory and nonlinear von-Karman strain-displacement relation are employed to investigate the aeroelastic behavior of the smart laminated panel. The thermodynamic behaviors of SMA wires are simulated based on one-dimensional Brinson SMA model. The aerodynamic pressure on the panel is described by the nonlinear piston theory. Nonlinear governing partial differential equations of motion are derived for the panel via the Hamilton principle. The effects of ply angle of the composite panel, SMA layer location and orientation, SMA wires temperature, volume fraction and prestrain on the buckling, flutter boundary, and amplitude of limit cycle oscillation of the panel are analyzed in detail.

Study on the Temperature of the Bridge Wire in the Initiator Used in Nuclear Explosion Valve

This paper established the mathematical model of bridge wire temperature rise under direct current condition and gave the solution. It computed bridge wire temperature by using the thermal-electric coupling method provided by ANSYS-Workbench finite element analysis software. In the end, the temperature bridge wire applied to different electric current was measured by the infrared thermal imaging temperature measurement method. The result shows that the ANSYS simulation results are in agreement with the theoretical calculation and the experimental results. It is feasible to compute bridge wire temperature of initiator by using ANSYS-Workbench software, and it is an important method to analyze complex structure of pyrotechnics.

Monitoring System Design of Underground Repository for Radioactive Wastes – In Situ Demonstrator

This paper describes the qualification of sensors envisioned for Cigeo, the planned deep disposal center for French radioactive waste. More precisely, it describes an in situ demonstrator, similar with the system planned to monitor intermediate level long lived radioactive wastes cells. These cells would be a tunnel, located 490 m deep, with 9 m in diameter, with concrete liners realized in three steps. The demonstrator was instrumented in 2011 in the Andra's Underground Research Laboratory. The instruments provide useful information on sensors' adaptability to the environment; robustness and technology comparisons (accordance and discrepancies). As an example, accordance between localized sensors and distributed measurements for strains, by optical fiber sensors and vibrating wire extensometers and temperatures, by optical fiber sensors and platinum probe, was verified. After 3 years more than 95% of sensors still provide measurements and show no drift over time.

External natural convection from a Joule heated horizontal platinum wire in water at low Rayleigh number

We report an experimental study of external natural convection from a Joule heated horizontal platinum wire immersed in water in a relative large cavity. Through that the platinum wire was used both as a heater and a thermistor for measuring a small temperature increment, our experiments were performed with much lower Rayleigh numbers in a range from 10−5 to 10−2 for water. Contrary to the general expectation, it is found that a local minimum Nusselt number happens at a critical Rayleigh number, which are about 5.0×10−4 and 1×10−4 for the platinum wires with diameters of 50.8μm and 20.1μm, respectively. The Nusselt number decreases rather than increases as usual with Rayleigh number before reaching the critical value, and the temperature of platinum wire fluctuates wildly over time at the critical condition. Corresponding experiments by using silicon oil instead of water, however, did not show such phenomena, which indicate that natural or free convection from a micro object may be fluid dependent.

Pool boiling heat transfer driven by an acoustic standing wave in terrestrial gravity and microgravity

Terrestrial and microgravity pool boiling generated from a platinum wire heater in the presence of an acoustic standing wave were performed using degassed FC-72 Fluorinert liquid. The sound wave was created by driving a half wavelength resonator at a frequency of 10.15kHz. Microgravity conditions were created using the 2.1 second drop tower on the campus of Washington State University. Burnout of the heater wire, often encountered with heat flux controlled systems, was avoided by using a constant temperature controller to regulate the heater wire temperature. The amplitude of the acoustic standing wave was increased from 28kPa to over 70kPa and these pressure measurements were made using a hydrophone fabricated with a small piezoelectric ceramic. Cavitation incurred during experiments at higher acoustic amplitudes contributed to the vapor bubble dynamics and heat transfer. The heater wire was positioned at three different locations within the acoustic field: the acoustic node, antinode, and halfway between these locations. Complete boiling curves are presented to show how the applied acoustic field enhanced boiling heat transfer and increased critical heat flux in the terrestrial environment, while in microgravity the acoustic field was found to be capable of filling the role of terrestrial gravity in maintaining nucleate boiling. Video images provide information on the interaction between the vapor bubbles and the acoustic field.

Thermal aware floorplanning incorporating temperature dependent wire delay estimation

Temperature has a negative impact on metal resistance and thus wire delay. In state-of-the-art VLSI circuits, large thermal gradients usually exist due to the uneven distribution of heat sources. The difference in wire temperature can lead to performance mismatch because wires of the same length can have different delay.Traditional floorplanning algorithms use wirelength to estimate wire performance. In this work, we show that this does not always produce a design with the shortest delay and we propose a floorplanning algorithm taking into account temperature dependent wire delay as one metric in the evaluation of a floorplan. In addition, we consider other temperature dependent factors such as congestion and interconnect reliability.The experiment results show that a shorter delay can be achieved using the proposed method.

Numerical Analysis of Transient Temperature Response of Soap Film

Measurements of thermophysical properties of thin liquid films are important to understand interfacial phenomena due to film structures composed of amphiphilic molecules in soap film, phospholipid bilayer of biological cell and emulsion. A transient hot-wire technique for liquid films less than 1 $$\upmu $$ m thick such as soap film has been proposed to measure the thermal conductivity and diffusivity simultaneously. Two-dimensional heat conduction equations for a solid cylinder with a liquid film have been solved numerically. The temperature of a thin wire with liquid film increases steeply with its own heat generation. The feasibility of this technique is verified through numerical experiments for various thermal conductivities, diffusivities, and film thicknesses. Calculated results indicate that the increase in the volumetric average temperature of the thin wire sufficiently varies with the change of thermal conductivity and diffusivity of the soap film. Therefore, the temperature characteristics could be utilized to evaluate both the thermal conductivity and diffusivity using the Gauss–Newton method.

Retraction. Ultrahigh magnetoresistance at room temperature in molecular wires.

Retraction. Ultrahigh magnetoresistance at room temperature in molecular wires.

Decomposition processes of H3NBH3 (borazane), (BH)3(NH)3 (borazine), and B(CH3)3 (trimethylboron) on heated W wire surfaces

The decomposition mechanisms of H3NBH3, (BH)3(NH)3, and B(CH3)3 on heated W wire surfaces were examined using mass spectrometric and laser spectroscopic techniques. These chemicals can be source materials for catalytic chemical vapor deposition as well as for B-atom doping. All the species could be decomposed well when the wire temperature was over 2.0×103K. When H2 was introduced, the production of B atoms was confirmed in the decomposition of H3NBH3 and B(CH3)3, but not for (BH)3(NH)3. H3NBH3 and B(CH3)3 may be candidates as safe precursors for B-atom doping, while (BH)3(NH)3 could be a viable candidate as a BN film precursor.

전기철도 전차선로의 설치 상태 판단을 위한 복합검측 기술 구현

The railway catenary systems consist of a complex structure, electrical and mechanical conditions are exposed to dangerous environment due to current collection between pantograph and catenary systems. These two types of conditions for the catenary systems are critically assessed for management and are becoming increasingly more dependent on reliable inspection system. In this paper, a new measurement system which enables inspection of catenary faults was studied and implemented. The system uses wavelength band of ultraviolet (UV) and IR (Infrared) to measure the insulation of corona and temperature of catenary wire. In order to determine the sensitivity of implemented system, the performance test such as distance detection range of UV camera and temperature resolution of IR camera were conducted, respectively. The field test of development system was also conducted in metro and high-speed line using mobile type UV and IR multi-composited measurement systems.

Control of wire transfer behaviors in hot wire laser welding

Hot wire laser welding reduces the requirement of wire feeding accuracy and improves wire deposition efficiency with preheating wire by resistance heat. Due to merits like low heat input and high deposition rate, this method has broad potential applications like welding and additive manufacturing. It is a key problem to maintain stable wire transfer in hot wire laser welding since the preheated wire should be kept contacted with the work piece to maintain high temperature. A high-speed imaging system was used to observe wire transfer behaviors, which are divided into three types: fusing transfer, continuous transfer, and wire hit transfer. Only the continuous transfer is the stable wire transfer, which guarantees good weld formation. The wire transfer behavior is determined by wire temperature, and the temperature criterion of wire transfer is obtained by image analysis and temperature measurement. Two characteristic points P1 and P2 on the filler wire were found out, whose temperatures were used to judge wire transfer behaviors. The temperature criterion of the stable wire transfer is interpreted that the temperature of P1 (TP1) must be no more than the wire solidus and the temperature of P2 (TP2) must be no less than the wire liquidus. A heat conduction model of hot wire laser welding was established to calculate TP1 and TP2 for the used 308-L stainless wire. The welding parameters, which made up isothermal surfaces of TP1 = 1398 °C and TP2 = 1454 °C, respectively, the solidus and liquidus of the used wire, were obtained by iteration calculation of wire temperature. The parameters window of the stable wire transfer was located between the two isothermal surfaces. For the stable wire transfer in hot wire laser welding, the resistance heat of the wire cannot exceed the heat which fuses the wire tip outside the molten pool. Meanwhile, the total heat of the wire, including the resistance heat and the heat conducted from the molten pool, must exceed the heat which melts the wire tip inside the molten pool.

Phonon-engineered thermal transport in Si wires with constant and periodically modulated cross-sections: A crossover between nano- and microscale regimes

The transition between nanoscale and microscale thermal transport regime at room temperature in silicon wires with constant and periodically modulated cross-section is theoretically investigated. Extrapolating the calculated thermal conductivity from the nano- to micrometer range, we find the characteristic dimensions of the wires where a crossover between nanoscale and microscale thermal transport occurs. This crossover is observed in both generic (smooth) and cross-section-modulated wires. In case of smooth silicon wires, we reveal a strong dependence of the crossing point position on the boundary roughness. For silicon wires with weak boundary roughness, the crossover occurs at cross-sections ∼60 nm × 300 nm, while for very rough boundaries it occurs at cross-sections ∼150 nm × 750 nm. In case of the periodically modulated wires, the crossover between nano- and microscale regimes occurs at typical cross-sections ∼120 nm × 120 nm of the narrow segment, and it is almost independent of boundary roughness. A strong distinction from the case of smooth wires is attributed (i) to the different trends at the nanometer scale, wherefrom the extrapolation was performed, and (ii) to the different phonon–boundary scattering due to the specific geometry. For modulated silicon wires, the influence of modulation thickness, modulation length, and cross-sectional area on the phonon thermal conductivity at the room temperature is analyzed. A possibility of thermal transport engineering in cross-section-modulated wires by resizing them is revealed in both nano- and microscale regimes. The presented results pave the way towards a better understanding of thermal transport reduction in Si nanowires with engineered diameter modulations and shed light on the crossover between nano- and microscale regimes of thermal transport.

Characterization of the frictional losses and heat transfer of oscillatory viscous flow through wire-mesh regenerators

In this paper, new relations for calculating heat transfer and pressure drop characteristics of oscillatory flow through wire-mesh screen regenerator such as Darcy permeability, Forchheimer’s inertial coefficient, and heat transfer area per unit volume, as a function of the wire diameter are presented. According to the derived relations, thinner wires have higher pressure drop and higher heat transfer rate. The relations are applicable for all regenerative cryocoolers. Embedding the new relations into a numerical model, three Stirling-type orifice pulse tube cryocoolers with three regenerators different in length and diameter but same volume in a variety of wire diameters, have been modeled. The results achieved by the model reveal that the local heat transfer coefficient decreases with increase of the wire diameter and the length-to-diameter ratio. In addition, it was shown that the mean absolute gas–solid wire temperature difference is a linear function of wire diameter in the range investigated. The results show that for larger length-to-diameter ratios, Forchheimer’s effect will dominate frictional losses, and the variations of the frictional losses are proportional to the inverse of the wire diameter. Wire diameter has been optimized to maximize the coefficient of performance of the cryocooler. Shorter regenerators have thinner optimum wires.

Development of MgB2 superconducting wire for the low activation superconducting magnet system operated around core D-T plasma

MgB2 is one of the “low activation superconductors”, because the half-life of the induced radio-activity on the MgB2 is much shorter than that of Nb-based superconductors such as NbTi, Nb3Sn and Nb3Al. MgB2 wire would become an alternative material for Nb-Ti wire for the Poloidal Field and correction feedback coils, if the critical current density (Jc) around the magnetic field of 4T could be improved. We found that addition of Cu using the compound Mg2Cu was an effective method to enhance Jc and succeed to fabricate 100m length of MgB2 wire with Cu addition. Jc of the 100m long MgB2 with Cu addition was comparable to that of a NbTi wire, and the small solenoid coil using Cu added MgB2 wire reached a central magnetic field of 2.62T. We found that MgB2 wire is an alternative material to commercial NbTi wires under the hard neutron irradiation in a fusion reactor. Furthermore, we also fabricated a Cu added MgB2 wire using isotope pure boron-11 (11B) powder as the boron source to reduce the radioactivity. The critical temperature (Tc) of the MgB2 wire using 11B powder was found to be 37K, and Tc was found to be changed by different boron materials.

Online Antiicing Technique for the Catenary of the High-Speed Electric Railway

To solve problems of catenary icing, this paper presents an online antiicing technique using the Joule effect on the catenary of the high-speed electric railway. According to its scheme, a couple of static var generators (SVGs) are, respectively, placed at the traction power substation and sectioning post to automatically generate an adjusted current, varying with the change of temperature, wind speed, and traction load, which will be obtained by online monitoring. The online antiicing current is not only determined by the developed heat balance equation for the contact wire, but also the developed relationship of the distributed current on catenary and the voltage of the traction network. The simulation and experimental results on an autotransformer (AT) traction power-supply system illustrate that the temperature of the contact wire can be maintained above 0 $^{\circ}$ C with the antiicing current and the voltage of traction network also in the normal range.

Effects of the porous media distribution on the performance improvement for isothermal chamber

In order to improve the isothermal performance of isothermal chamber, how the distribution of thin copper wire on chamber cross-section enhances the heat transfer from wall to center was studied in this paper. Firstly, the heat conduction model was established and the temperature fields and the center temperature were calculated under the condition of the copper wire was stuffed uniformly. Secondly, under the circumstance that the temperature of chamber wall, the average stuffed density of copper wire and initial temperature in the center were certain, taking the maximum of center temperature as the optimization objective after heat conduction lasting 15 s, the variable density method and the adaptive growth method were used respectively to optimize the distribution of copper wire in order to enhance the heat conduction from the chamber wall to the center. Compared with the uniformly filling, the results of the center temperature were increased 4.94% and 16.50% respectively. Moreover the corresponding copper wire porosity distribution curves were obtained. Finally, the copper wire in the isothermal chamber was layered filled based on the optimized results. Then the verification experiments and verification simulation were carried out to verify that change the distribution of copper wire could enhance the heat conduction from the wall to center. Moreover, according to the results of discharging experiments for isothermal chamber, it was verified that the filling scheme could improve the isothermal performance of isothermal chamber.

Three-dimensional characteristics analysis of the wire-tool vibration considering spatial temperature field and electromagnetic field in WEDM

In this paper, a three-dimensional multi-physics coupling model (thermal model, electromagnetic field model and structural model) is proposed for analyzing and controlling the vibration of wire electrode in cutting thin plate process. Firstly, a three-dimensional thermal model is developed to evaluate temperature distribution of wire electrode considering heat convection and heat conduction, and the numerical solutions of wire temperature increment are performed under different process parameters. Secondly, the mechanism of electromagnetic force acting on wire tool is clarified in detail, and a spacial finite element method (FEM) program is designed to analyze the electromagnetic field considering electromagnetic induction. Then, combining thermal model with electromagnetic field model, and conventional structural model, a multi-physics coupling model is established to acquire the frequency and amplitude of wire vibration under random multiple-spark discharges. Furthermore, the simulational results of multi-physics coupling model on wire vibration show a good agreement with experimental data, and the influencing rules of processing parameters on wire vibration are also illustrated to seek the best parameter combination. Eventually, three practical methods are presented to restrain wire vibration performance, and the significant effects on suppressing the wire vibration and improving geometric accuracy have been obtained. • A three-dimensional characteristics analysis of the wire-tool vibration considering spatial temperature and electromagnetic field has been carried out in this paper. Furthermore, combining the thermal model with electromagnetic field and structural mechanics, a multi-physics coupling model has been developed to calculate frequency and amplitude of wire vibration by finite element method. • A set of Taguchi experiment ( L 27 5 3 ) has been performed to investigate the reliability and feasibility of the proposed coupling model. Moreover, the simulational results of multi-physics coupling model on wire vibration show a good agreement with experimental data. • Three practical methods have been presented to restrain wire vibration performance, and the lateral vibration has been reduced with approximately 50% and corner-accuracy of a workpiece has been improved significantly.

Temperature Field Analysis of 400 MN Heavy Die Forging Press Based on Finite Element Method

Heat conduction and thermal radiation of workpiece could increase temperature of the steel wire wound frame and the moving beam, which may lead to huge creep deformation, pre-stress loss of steel wire and performance degradation of the hydraulic oil. So it is practically important to analyze the temperature field of the die forging press. Steady and transient temperature field analyses are performed for 400 MN forging press by using ABAQUS to study the temperature field characteristics of the ejection cylinder and steel wires of the moving beam and the frame. The results show that when working temperature of the die is 300 ℃,wire temperature is below 75 ℃ after 48 h, while oil temperature is above 70 ℃ after 8.4 h, the latter exceeds the permit limit. Since the improvement of heat dissipation could not decrease temperature effectively, scheme A in which the heat insulation gaskets are added to the bottom and the top of the cylinder and scheme B in which the insulation gaskets are added between the die and the die holder are proposed. It is verified by the simulation that the latter could decrease oil temperature effectively and meet the design requirements, the oil temperature could keep below 70 ℃ after 48 h. The FEM results agree well with the experimental data, which verifies the validity of the FEM modeling. This work provides beneficial reference for structural design and forging process design.

Design of one Electrothermal Cutting Machine Used for Producing Packaging Material

Based on the problems of low precision, single-function of the plastic molding machine, a smaller electrothermal cutting machine is developed and designed, which is composed with processing platform, positioning clamp, resistance wire conjoined chuck, cantilever beam, fixed mounts, etc. Regulate the temperature of resistance wire to achieve the cutting of foam model with different melting point by adjusting voltmeter and regulating transformer; adjusting the rotatable positioning cones meshed with the adjusted range of positioning clamp and the adjustable distance between positioning clamp and resistance wire can make model with different requirements. The machine is mainly used in cutting and molding of plastic materials, such as foam and sponge, during the experimental teaching and advertising design. Results of the performance test show that using the machine with auxiliary manual operation is more convenient, efficient and accurate than the traditional making process of plastic model.

Influence of the Materials Combination for the Surface Temperature of the Bimetallic Wire Deformed in the Cold Drawing Process

The article discusses the mathematical and practical methodology for evaluating the temperature on the surface of bimetallic wire after deformation in the drawing die. The components of bimetallic wire on the cross-section are the following materials: - a core, brass M63 (CuZn37) - shell M1E copper (Cu – ETP), - a core, aluminum Al (A199, 5) - shell M1E copper (Cu – ETP). An outer layer (shell) in such combinations is always a copper with two different thicknesses of 1.5 mm and 0.5 mm, which means that the proportion of copper on the cross section of the bimetal was respectively 64% and 32%. The bimetallic wires samples used for measurements were obtained by mechanical cladding. In the first step of the process, the cooper tubes M1E were put on the aluminium and brass wires M63, and then in a second step, each set combination was subjected to a simultaneous deformation with a total true strain φlc~ 1. Thus obtained the bimetal wires were the blank material for determining the surface temperature. In the drawing process there were used two different drawing speeds, and for each was applied the two individual size of deformation of 15% and 30%. The temperature on the surface of the layered wire depending on the single deformation and drawing speed was determined using a thermographic camera and it was also calculated according to mathematical formulas. The article discusses the preliminary results necessary to conduct further deliberations on the temperature decomposition on the longitudinal section of the bimetallic wire deformed in the drawing die.