Effect of Shell Temperature on Thermal Resistance and Junction Temperature for Power Diode

Accurate measurement of junction temperature can avoid thermal failure of diode. During aging test, junction temperature should be indirectly calculated by testing its thermal resistance. In this paper, junction-to-case thermal resistance (Rthjc) of XX diode is tested by T3ster based on transient dual interface method. Its Rthjc is about 1.23K/W at 25°C and contains PN junction thermal resistance, metal shell thermal resistance and Sn-based solder thermal resistance, respectively. These three types of thermal resistance decrease in order. Effect of shell temperature on junction temperature and Rthjc is then discussed. As shell temperature increases, temperature variation of PN junction before and after heating and corresponding thermal resistance Rthjc both increase.

Optimizing Walnut Storage Conditions: Effects of Relative Humidity, Temperature, and Shelling on Quality after Storage

With increasing walnut production in California, walnuts are stored for longer times. It is increasingly important to optimize storage conditions, wherever possible, to reduce quality degradation. We examined the effects of temperature (5, 15, and 25 °C) and relative humidity (20%, 40%, and 60% in year 1 and 40%, 60%, and 80% in year 2) on the rate of quality degradation of four walnut varieties. The relationship between water activity and moisture content was investigated for each variety. In addition, the effects of harvest timing (early vs. late) and storage as shelled or in-shell product were investigated. Later harvested walnuts had darker kernel color (P < 0.001), and walnuts stored as kernels (shelled) had higher rates of peroxide formation and free fatty acid development than walnuts stored in-shell. Temperature had a significant effect on quality with faster degradation at higher temperatures. There was a significant interaction between temperature and relative humidity effects on quality. The effects of relative humidity were often not significant at storage temperatures of 5 °C but were apparent at 15 °C and at 25 °C. Managing relative humidity during walnut storage is difficult under typical commercial storage conditions; however, when low temperature storage is used, quality is preserved even when relative humidity is not controlled, although storage at 80% relative humidity should be avoided. To reduce the rate of color darkening and rancidity development during commercial storage, operators should emphasize storage at lower temperatures, at least below 15 °C.

Japon Bıldırcınlarında Yumurta Ağırlığı, Kuluçka Sıcaklığı ve Kabuk Sıcaklığının Kuluçka Sonuçlarına Etkilerinin Belirlenmesi

In this study, a total of 402 Japanese quail hatching eggs from 32 weeks of age flock to determine shell temperature, temperature differences between shell and setter temperatures, relative weight (water) loss from eggs in setter period and effects on incubation results. All the eggs were divided into two egg weight groups (≤12 g and >12 g) and they were randomly and equally distributed to the setter trays. As expected, day old chick weight was significantly affected by the egg weight. The lighter eggs lost more water than heavier ones. Although the embryo cannot produce a noticeable level of heat in the first half of the development period (endothermic phase), since it begins to generate more noticeable heat in the second half (exothermic phase), the shell temperature is found to be higher than the setter temperature. This table is more pronounced in heavier eggs. In the first half of the development period, while the shell temperature was higher in light eggs than in heavy ones, the shell temperature, in egg weight groups, was differed by the setter floors during the latter half. Generally, in this late period, when the growing embryo now produces more noticeable heat, the higher shell temperatures were measured in heavier eggs and in eggs where set in upper-trays. The lighter eggs where set in lower-trays were found to be having lower shell temperatures than the eggs in all other combinations. Late embryonic mortalities were higher in heavier eggs.

Fabrication of a novel core–shell–shell temperature-sensitive magnetic composite with excellent performance for papain adsorption

A novel core–shell–shell temperature-sensitive magnetic composite was designed. The composites showed excellent performance for papain adsorption and could thermally protect papain.

Modelling R Coronae Borealis stars: effects of He-burning shell temperature and metallicity

ABSTRACT The R Coronae Borealis (RCB) stars are extremely hydrogen-deficient carbon stars that produce large amounts of dust, causing sudden deep declines in brightness. They are believed to be formed primarily through white dwarf mergers. In this paper, we use mesa to investigate how post-merger objects with a range of initial He-burning shell temperatures from 2.1 to 5.4 × 108 K with solar and subsolar metallicities evolve into RCB stars. The most successful model of these has subsolar metallicity and an initial temperature near 3 × 108 K. We find a strong dependence on initial He-burning shell temperature for surface abundances of elements involved in the CNO cycle, as well as differences in effective temperature and radius of RCBs. Elements involved in nucleosynthesis present around 1 dex diminished surface abundances in the 10 per cent solar metallicity models, with the exception of carbon and lithium that are discussed in detail. Models with subsolar metallicities also exhibit longer lifetimes than their solar counterparts. Additionally, we find that convective mixing of the burned material occurs only in the first few years of post-merger evolution, after which the surface abundances are constant during and after the RCB phase, providing evidence for why these stars show a strong enhancement of partial He-burning products.

A neutron scattering perspective on the structure, softness and dynamics of the ligand shell of PbS nanocrystals in solution

Time-averaged and energy-resolved neutron and X-ray scattering reveal the structure of the ligand shell, temperature-dependent diffusion and the phonon spectrum of PbS nanocrystals functionalized with oleic acid in solution.

LSTM based prediction algorithm and abnormal change detection for temperature in aerospace gyroscope shell

Purpose Abnormal changes in temperature directly affect the stability and reliability of a gyroscope. Predicting the temperature and detecting the abnormal change is great value for timely understanding of the working state of the gyroscope. Considering that the actual collected gyroscope shell temperature data have strong non-linearity and are accompanied by random noise pollution, the prediction accuracy and convergence speed of the traditional method need to be improved. The purpose of this paper is to use a predictive model with strong nonlinear mapping ability to predict the temperature of the gyroscope to improve the prediction accuracy and detect the abnormal change. Design/methodology/approach In this paper, an double hidden layer long-short term memory (LSTM) is presented to predict temperature data for the gyroscope (including single point and period prediction), and the evaluation index of the prediction effect is also proposed, and the prediction effects of shell temperature data are compared by BP network, support vector machine (SVM) and LSTM network. Using the estimated value detects the abnormal change of the gyroscope. Findings By combined simulation calculation with the gyroscope measured data, the effect of different network hyperparameters on shell temperature prediction of the gyroscope is analyzed, and the LSTM network can be used to predict the temperature (time series data). By comparing the performance indicators of different prediction methods, the accuracy of the shell temperature estimation by LSTM is better, which can meet the requirements of abnormal change detection. Quick and accurate diagnosis of different types of gyroscope faults (steps and drifts) can be achieved by setting reasonable data window lengths and thresholds. Practical implications The LSTM model is a deep neural network model with multiple non-linear mapping levels, and can abstract the input signal layer by layer and extract features to discover deeper underlying laws. The improved method has been used to solve the problem of strong non-linearity and random noise pollution in time series, and the estimated value can detect the abnormal change of the gyroscope. Originality/value In this paper, based on the LSTM network, an double hidden layer LSTM is presented to predict temperature data for the gyroscope (including single point and period prediction), and validate the effectiveness and feasibility of the algorithm by using shell temperature measurement data. The prediction effects of shell temperature data are compared by BP network, SVM and LSTM network. The LSTM network has the best prediction effect, and is used to predict the temperature of the gyroscope to improve the prediction accuracy and detect the abnormal change.

Margins Assessment of Pressure-Temperature Limit Curves for a RPV

In order to prevent brittle fracture, the pressure and temperature in a reactor pressure vessel (RPV) is controlled by pressure-temperature (P-T) limit curves during the heat-up and cool-down processes. Nuclear power plants should update the P-T limit curves periodically, because of RPV material irradiation embrittlement. Too restricted P-T limit curves may cause difficulty of operating a reactor. The 2007 edition of the RCCM code Annex ZG provides a new method for defining the P-T limit curves. In this paper, two types of the P-T limit curves for a French type RPV are established by different methods, which are the current operation limits based on the 1993 edition of the RCCM code and the new proposed limits according to the 2007 edition of the code. The margins of the current P-T limit curves are evaluated by comparing with the new proposed limit curves. Furthermore, the reasonability of improvements of the new P-T limit curve method is discussed, and their individual effects are investigated, including the conventional defect size, the required material toughness and the stress intensity factor plastic correction. The present results indicate that the current P-T limit curves for the RPV studied are conservative and have about 25∼70 °C margin in the transition temperature range and about 10∼12MPa in the upper shell temperature range, depending on different conditions. The new P-T limit curve method, which not only removes some conservative assumptions in the previous method but also restricts some requirements, is more reasonable and can provide a relaxed operation window. Present results can be a reference for the nuclear power plant owner to release the operation limits and is helpful in enhancing our understanding of the P-T limit curve.