Average Temperature Error Research Articles

Prediction and analysis of breakthrough extruding force based on a modified FE-model in large-scale extrusion process

P91 steel is considered an appropriate material for high-quality pipes used in nuclear plant. In the extrusion process on 680-million-newton-tonnage forging and extruding machine to manufacture long seamless P91 pipes with large diameter and wall-thickness, the extruding force peak during the process will exceed 500 million newtons. For security consideration, prediction of extruding force, especially breakthrough force, must be accurate to avoid accidents like jamming. A modified finite element model has been developed to predict the extruding force in large-scale glass lubricant hot extrusion of P91 pipes and declare the relationship between the friction ratio and container temperature. On the basis of the practical extrusion results obtained on 360-million-newton-tonnage extruding machine and characteristics of large-scale extrusion, the billet cooling period and new viscous friction model on billet–container interface are added or established as the modification on the most significant sensitive factors. Using the modified model, the average temperature error after cooling is 3.23 °C and the maximum decrease of simulation results of breakthrough extruding force on 360-MN machine is 17 MN. The predicted results correspond to the decreasing tendency of the measured ones. The deviation between the simulated breakthrough extruding force and measured one on 680-MN machine is only 0.3%, which validates the accuracy of force-predicting model. This study may offer the basis for precise prediction for complete large-scale extrusion process and provide guidance to reduce the breakthrough force in the extrusion process.

Evaluation of 3D measurement using CT-TDLAS

In order to satisfy the requirements of high quality and optimal material manufacturing process, it is important to control the environment of the manufacturing process. Depending on these processes, it is possible to improve the quality of the product by adjusting various gases. With the advent of the tunable laser absorption spectroscopy (TDLAS) technique, the temperature and concentration of the gases can be measured simultaneously. Among them, computed tomography-tunable diode laser absorption spectroscopy (CT-TDLAS) is the most important technique for measuring the distributions of temperature and concentration across the two-dimensional planes. This study suggests a three-dimensional measurement to consider the irregular flow of supplying gases. The simultaneous multiplicative algebraic reconstruction technique (SMART) algorithm was used among the CT algorithms. Phantom datasets have been generated by using Gaussian distribution method. It can show expected temperature and concentration distributions. The (HITRAN) database in which the thermo-dynamical properties and the light spectra of H2O are listed were used for the numerical test. The relative average temperature error ratio in the results obtained by the SMART algorithm was about 3.2% for temperature. The maximum error was 86.8 K.

LoCool: Fighting Hot Spots Locally for Improving System Energy Efficiency

Elevated on-chip temperatures significantly degrade performance, energy-efficiency, and lifetime of processors. The cooling system for a chip is typically designed to remove the worst-case heat generated per unit area. Cooling demand, however, spatially and temporally varies across a chip as hot spots occur on different locations with different intensities. Thus, designing a homogeneous cooling system for a chip can be inefficient. Recently, hybrid cooling strategies, such as integrating thermoelectric coolers (TECs) with microchannel liquid cooling, have been explored for hot spot mitigation. The efficiency of such a cooling system strongly depends on the operating point of each cooling method, as well as the locations and intensities of the hot spots. To this end, we first devise a compact thermal modeling method for the design and evaluation of hybrid cooling systems in a fast and accurate way. The proposed model provides up to four orders of magnitude speedup in simulation time compared to COMSOL multiphysics simulations with less than 2.9 °C average temperature error. Leveraging our fast model, we develop LoCool, a hybrid cooling optimization method, which jointly determines the most energy-efficient cooling settings for a given chip power distribution and temperature constraint. LoCool determines the liquid flow rate and the input current for each TEC depending on the cooling requirements for individual hot spots as well as for the background heat. Experimental evaluation shows up to 40% cooling energy savings compared to designing homogeneous cooling systems under the same thermal constraints.

Improvement of Temperature Control Performance of Thermoelectric Dehumidifier Used Industry 4.0 by the SF-PI Controller

This paper proposes the series connected fuzzy-proportional integral (SF-PI) controller, which is composed of the fuzzy control and the PI controller to improve temperature control performance of dehumidifier using a thermoelectric element. The control of conventional PI controller usually uses fixed gain. For that reason, it is limited in achieving satisfactory control performance in both transient-state and steady-state. The fuzzy control within SF-PI controller adjusts the input value of PI controller according to operating condition. The PI controller within the SF-PI controller controls the temperature of the thermoelectric element using that value. The SF-PI controller can achieve more accurate temperature control than a conventional PI controller for that reason. The SF-PI controller has been tested for various indoor environmental conditions such as temperature and relative humidity conditions. The average temperature error of the SF-PI controller between the reference temperature and the thermoelectric element temperature is 22% of traditional PI’s value and consumption power is reduced by about 10%. Therefore, the SF-PI controller proposed in this paper can improved the performance of temperature control of dehumidifier using thermoelectric element. The power consumed by buildings accounts for a significant portion of the total power consumption, of which the air conditioner represents the largest energy consumer. In this paper, it is possible to reduce the energy consumption by improving the performance of the dehumidifier, one of the air conditioners, and it can be applied to various control fields in the future.

Experimentally validated numerical model of thermal and flow processes within the permanent magnet brushless direct current motor

In this paper, a numerical model describing the heat transfer and air flow inside and outside the casing of the permanent magnet brushless direct current (PM BLDC) motor is presented. In the model, a conjugate heat transfer including the heat conduction with heat sources in windings, magnets, bearings, natural and forced convection and radiation phenomena within internal and external air domain were analysed. The complex geometrical model included windings, a magnet circuit, a rotor with neodymium magnets, a PCB electronic plate, plastic covers, internal air between solid parts as well as a portion of the external air. The validation process of the developed model was realised on the basis of the velocity and temperature fields. The experimental data were recorded by 7 constant temperature anemometers at 4 levels above the motor housing, Laser Doppler Anemometry sensors in two axes inside the rear portion of the motor and 25 thermocouples fixed inside and outside the motor. The experimental and numerical tests were performed for 4 motor loadings and 3 rotational speeds. The average temperature error for the internal point was of 9 K, while that of the external points was of 2 K. The velocity field was very well predicted close to the housing wall in terms of horizontal and vertical components. A slightly worse agreement was found for the vertical component, especially in the vicinity of the shaft. The results were consistent for all the considered motor loadings and rotational speeds.

2 m survey method and its improved device application in Dongshan geothermal field in Xiamen in China

Preliminary geothermal surveys to identify areas of potential geothermal anomalies are the most important stage in traditional hydrothermal-type geothermal resource exploration procedures. Temperature gradient wells are limited because of their accessibility issues and high costs, whereas the 2 m survey is considered a rapid, efficient, and inexpensive method to measure temperature accurately and allow for rapid vectoring toward geothermal anomalies in cases where thermal groundwater is not overlain by near-surface cold aquifers. An improved quick and portable measurement device is developed that adds in situ thermal conductivity tests based on temperature. The device, which is easy to assemble, portable, and suitable for two or three people in field work, had been calibrated by laboratory experiments. The device was applied in Dongshan geothermal field, Xiamen City in China, and 18 measurement positions were arranged. Results clearly described the geothermal anomalies in the area and revealed two temperature anomaly centers, namely a strong one in the eastern area and a weak one in the western area. Moreover, a speculated fault provided a hydraulic connection between the eastern and western areas. According to the 2 m survey, a steady-state heat conduction model has been used to inverse the 20 m temperature. The average temperature error of all boreholes in 20 m is 3 °C, whereas the relative errors between actual and forecast values are less than 10 %. Therefore, the 2 m survey method and improved device shows good performance in preliminary geothermal surveys.

Ambient condition desensitization of a fiber Raman temperature sensing system based on a dynamic sampling-correction scheme.

One of the most important performance indicators of a fiber optic distributed temperature sensing (DTS) system is its operational stability, which depends on the performance of each device making up the system. Such individual device performance itself is affected by temperature and other environmental conditions. As a result, ambient fluctuations invariably lead to measurement uncertainties and drifts, seriously degrading the system performance. To ameliorate such adverse effects of the environment, we propose a dynamic sampling-correction scheme, which we have implemented on our fiber optic Raman DTS system, resulting in an average temperature error within 1°C when the main chassis undergoes a temperature variation over the range -25°C-45°C. The drastically improved system stability foreshadows better performance and reliability in engineering applications.

Evidence for enhanced mixing on the super-meteoritic Li-rich red giant HD 233517

Context. HD 233517 is among the most Li-rich stars in the sky. It is a rapidly rotating, single K giant thought to be on its first ascent on the red giant branch. The star has also the highest known infrared excess among any of the known first-ascent giants.Aims. We revisit the physical parameters of the system and aim to map its surface temperature distribution.Methods. New time-series photometry and high-resolution spectroscopy were obtained with our robotic facilities STELLA and Amadeus Automatic Photoelectric Telescope (APT) in 2007–2011. Inverse line-profile modelling is performed on a total of 167 echelle spectra and six Doppler images are presented.Results. Light and radial-velocity variations suggest a stellar rotation period of 47.6±0.3 d. The atmospheric parameters agree with previous studies and verify a super-meteoritic log 7 Li abundance of 4.29±0.10 with undetected 6 Li, while the metals are generally deficient by –0.4 dex with respect to the Sun. We determine a lower than normal isotopic carbon ratio of 12 C/13 C = 9+4 -2 . Our Doppler images indicate warm and cool spots with an average temperature contrast of just ±65 K with respect to the effective temperature. Doppler maps from Li i 670.78 reveal practically identical surface morphology, with a higher average contrast of ±160 K and errors that are five times larger. Reconstructions with simultaneously 1617 and 3007 spectral lines showed both a signal degradation with respect to our 56-line final image. An error analysis indicates an average temperature error per surface pixel of just ±4 K. Conclusions. HD 233517 appears to be an old (≈10–Gyr) single 0.95–M ⊙ giant currently undergoing mild mass loss in the form of a wind. The cool and warm photospheric features are interpreted to be merely locations of suppressed and enhanced convection, respectively, probably intermingled by a yet undetected weak magnetic field. The low carbon-isotope ratio is indicative of extra mixing rather than of an engulfing event. We tentatively conclude that HD 233517 operates an enhanced non-axisymmetric mixing process that leads to an inhomogeneous super-granulation pattern on the surface in form of large cool and warm features.

Locatable-Body Temperature Monitoring Based on Semi-Active UHF RFID Tags

This paper presents the use of radio-frequency identification (RFID) technology for the real-time remote monitoring of body temperature, while an associated program can determine the location of the body carrying the respective sensor. The RFID chip's internal integrated temperature sensor is used for both the human-body temperature detection and as a measurement device, while using radio-frequency communication to broadcast the temperature information. The adopted RFID location technology makes use of reference tags together with a nearest neighbor localization algorithm and a multiple-antenna time-division multiplexing location system. A graphical user interface (GUI) was developed for collecting temperature and location data for the data fusion by using RFID protocols. With a puppy as test object, temperature detection and localization experiments were carried out. The measured results show that the applied method, when using a mercury thermometer for comparison in terms of measuring the temperature of the dog, has a good consistency, with an average temperature error of 0.283 °C. When using the associated program over the area of 12.25 m2, the average location error is of 0.461 m, which verifies the feasibility of the sensor-carrier location by using the proposed program.

Fabricating optical fibre-top cantilevers for temperature sensing

In this paper, we propose techniques to fabricate micro-cantilevers onto the end of standard single mode optical fibres using a combination of picosecond laser machining and focused ion beam milling techniques and demonstrate their use as temperature sensors. Using this approach the cantilever can be pre-aligned with the core of the fibre during fabrication, therefore offering a stable and straightforward means of optically addressing the cantilever. The cantilever is designed to measure deflection over a range of 10 µm using a simple readout technique. A phase recovery algorithm is employed to reduce the interrogation error to around 2–3 nm. Finally, a temperature cycling experiment demonstrates that the cantilever could be used as a temperature sensor from room temperature to 500 °C with an average rms temperature error from 20 °C to 500 °C of ∼±1.4 °C.

A Model for Water Surface Temperature Retrieval from HJ-1B/IRS Data and Its Application

Water surface temperature is one of the important environmental parameters at the breeding aquatics area in shore.The highly dynamic monitoring of this temperature will help to arrange aquaculture production and breeding production.Remote sensing technology is a very efficacious means for monitoring water surface temperature in high dynamic condition.At present,weather and ocean satellites which have lower spatial resolution are widely used in water surface temperature remote sensing monitoring,with the spatial resolution being 1 000 m.However,water bodies in shore are influenced by land and ocean as well as the spatial changes of water surface temperature,and hence satellites data which have higher spatial resolution are needed to meet the monitoring for water surface temperature in high dynamic condition.HJ-1B/IRS has a 4-band infrared sensor(IRS).One of the bands is the thermal band which can be used to retrieve water surface temperature.In this paper,data of about ten images of HJ-1B/IRS thermal band obtained from 2008 to 2009 and the atmosphere measurement data at the time when the HJ-1B satellite passed through the area were collected.Based on the monowindow algorithm and referring to the temperature product from EOS/MODIS,the authors established a model for water surface temperature retrieval from HJ-1B/IRS data.Moreover,a comparison was made between two retrieval methods for surface temperature from HJ-1B/IRS thermal band and from the temperature product by EOS/MODIS.The results show that the absolutely average temperature error from the monowindow algorithm and from the temperature product by EOS/MODIS is 7.84℃,while that from the method proposed in this paper is 0.83℃.The model for water surface temperature retrieval from HJ-1B/IRS data established in this paper was applied in the area of Liaodong Bay for the purpose of carrying out dynamic monitoring of water surface temperature.

Noninvasive thermometry assisted by a dual-function ultrasound transducer for mild hyperthermia

Mild hyperthermia is increasingly important for the activation of temperature-sensitive drug delivery vehicles. Noninvasive ultrasound thermometry based on a 2-D speckle tracking algorithm was examined in this study. Here, a commercial ultrasound scanner, a customized co-linear array transducer, and a controlling PC system were used to generate mild hyperthermia. Because the co-linear array transducer is capable of both therapy and imaging at widely separated frequencies, RF image frames were acquired during therapeutic insonation and then exported for off-line analysis. For in vivo studies in a mouse model, before temperature estimation, motion correction was applied between a reference RF frame and subsequent RF frames. Both in vitro and in vivo experiments were examined; in the in vitro and in vivo studies, the average temperature error had a standard deviation of 0.7°C and 0.8°C, respectively. The application of motion correction improved the accuracy of temperature estimation, where the error range was 1.9 to 4.5°C without correction compared with 1.1 to 1.0°C following correction. This study demonstrates the feasibility of combining therapy and monitoring using a commercial system. In the future, real-time temperature estimation will be incorporated into this system.

A surgical device for radiofrequency ablation of large liver tumors

Radiofrequency ablation has become an accepted treatment option of patients with primary and metastatic liver tumors. We propose an ablation electrode array consisting of 4–8 blade shaped electrodes arranged in a circular geometry for the treatment of large liver tumors. We developed a 3D code based on the finite difference method for evaluating the effect of different numbers of electrodes (4, 6 and 8) and electrode distance on lesion size. The configuration with six electrodes can ablate a volume of 70 × 70 × 40 mm3 in approximately 5 min, with tissue temperature above 50 °C throughout the treatment volume. We then performed an experimental study in polyacrylamide gel in order to validate the theoretical results. The average temperature error between the simulation and the experiment was 3.8% at the center of the electrode array. This study shows that the proposed device potentially allows more rapid treatment of large tumors than current radiofrequency ablation devices.

Extended-range predictions with ECMWF models: Interannual variability in operational model integrations

A set of 30-day integrations made with the operational ECMWF model over a period of three and a half years (from 1985 to 1988) is studied. the impact of model reformulations during this period on the climate drift of the model is assessed, and the level of extended-range forecast skill achieved by the operational model is studied. Diagnostics of zonal average 30-day mean wind and temperature error show a systematic reduction in the extratropics over three years. It is argued that these improvements are consistent with the changes in model formulation. Eddy fluxes of heat and momentum, and levels of eddy kinetic energy are similarly improved. We also show that the ability to simulate blocking activity in the extended range has improved substantially over the three winters. From maps showing the ratio of systematic to total error it is concluded that, by the final winter, the middle-latitude extended-range error is almost entirely associated with random errors. This is supported by the growth of the dispersion, or spread, between forecasts initialized 24 hours apart. In particular, for the extended winter 1987/88, it is shown that the asymptotic level of (internal) spread is comparable with the asymptotic level of (external) skill. By contrast, in the tropics, the total error is dominated by the systematic error for all years. Despite improvements to the model, extended-range forecast skill is modest. Skill has been measured in a spatially-filtered three-dimensional phase space, spanned by rotated EOF (empirical orthogonal function) coefficients of 500 mb height, which contain the principal weather regimes in the atmosphere. On average the skill scores are consistent with those of other major centres studying dynamical extended-range prediction. In particular there is evidence of skill to day 15 and possibly to day 20 in middle latitudes. Beyond day 20 skill is marginal. We demonstrate that in the winter sample of operational-model forecasts, skill is correlated with the observed value of the first rotated EOF, which can be described as a global version of the Pacific/North American mode. By contrast, the ability to predict monthly mean fields in the tropics depends primarily on a knowledge of the boundary forcing, including sea surface temperature. It is shown that some aspects of the interannual variations in the summer monsoon circulation can be predicted, in particular the tropical easterly jet anomalies, African rainfall, and, to a much lesser extent, Indian monsoon rainfall.