Rate Of Temperature Change Research Articles

Preliminary analysis of startup transient for an ultra-small lithium-cooled space reactor power system

A multi-phases startup scheme based on the reactor startup first, followed by the closed Brayton cycle (CBC) machinery was proposed for the startup condition of an ultra-small lithium-cooled space reactor power system (ULCR) with a CBC conversion system concept scheme. The scheme minimizes the auxiliary motor power required for the turbomachinery startup. The overall startup process includes 7 phases. In the low-power operation phase, by controlling the turbomachinery shaft speed and helium-xenon (He–Xe) working fluid mass flow, the turbomachinery output power was balanced with the needed motor power. Therefore, the auxiliary equipment of the power conversion system was minimized. As the turbomachinery speed and He–Xe mass flow increased to the rated conditions, the core was in low temperature and low power steady-state operation, which was conducive to keep system in safety conditions for the automatic control system. With the reactivity insertion, the core temperature was finally increased to the rated operating condition, and the CBC conversion system's output power increased to the rated output power. The transient process of the designed startup scheme was calculated and analyzed by using the developed transient analysis program TACSNR. The results show that the change rate of the core average temperature at the rising phases was less than 1.1 K s−1. During the whole startup process, the parameters of the ULCR system are all in the safe range.

ВИБІР ТЕХНОЛОГІЧНИХ ПАРАМЕТРІВ ЛАЗЕРА ДЛЯ ОТРИМАННЯ НАНОСТРУКТУР НА ІНСТРУМЕНТАЛЬНІЙ СТАЛІ У12А

According to the improved model of the thermal interaction of laser radiation and the processing material, a study of the change in the maximum temperature at different depths of the surface layer was carried out on the example of tool steel U12A. The rate of change of the maximum temperature and temperature stress as a function of the heat flux density of laser radiation (LV) was also studied. The range of LV density was taken within q=108...1011 W/m2 for different times of its action, which corresponds to the conditions for the possible occurrence of NS. The study of the dependence of the rate of change of the maximum temperature on U12A steel on the density of the heat flow at different depths showed that during all times of its action, rates of temperature change of more than 107 K/s are realized, which indicates that, according to this criterion, the formation of NS is possible over the entire range of densities heat flow and at all investigated depths. To determine the possibility of accelerating the formation of NS, the values of temperature stresses in the zone of action on U12A were calculated at a density of 108...1011 W/m2 at different depths with an action time of t=10-4 ...10-10c. Which showed that the direct formation of NS from the action of temperature stresses is practically impossible, however, at a time of 10-5...10-4 of their values, they approach those required at a heat flux density of 1011 W/m2. In order to determine the technological parameters that ensure the production of NS, spatial dependences of the volume of NS on the heat flux density and the time of its action were constructed for the radius of the spot R=10-6 m (Fig. 8) and R=5•107 m (Fig. 9) . It was determined that obtaining NS is more realistic for the size of the spot 5•107 m, although the probability of obtaining them is also low. In fig. 10 and 11 show similar dependences for the grain size on the heat flux density and the time of its action for the spot size R=10-6 m and R=5•107 m when acting on U12A tool steel. The obtained spatial pictures allow, knowing the required grain size, to choose the technological parameters that allow them to be implemented. All this will be required during the development of the technology for obtaining strengthening nanostructured coatings on the cutting tool.

Preliminary study of a dual channel solar photocatalytic ventilation wall system for year-round air purification and building energy savings

With the aim of meeting the weak adaptability to different seasons and low solar energy utilization efficiency for solar ventilation wall system. In the present work, a novel dual-channel solar photocatalytic ventilation wall (DSPVW) integrated with a photovoltaic (PV) panel and phase change materials (PCM) has been numerically proposed and simulated in winter and summer in subtropical climate zone. A range of performance indicators, such as outlet temperature, air heating gain, and clean air delivery rate (CADR), is evaluated. Furthermore, a comparative analysis is performed to assess the energy and exergy characteristics, distribution, comfortable temperature range percentage (CTRP), energy consumption and savings rate of three different systems: typical solar photocatalytic ventilation wall (SPVW), dual-channel solar photocatalytic ventilation wall (DSPVW), and DSPVW-PV/PCM. Results show that melting temperature of 313.15 K and 323.15 K respectively shows a good performance in winter and summer. The rate of temperature change and peak temperature to the outlet air slow down and decrease with the increase of PCM thickness, resulting in a cooling effect of 1.27 % and 2.83 % in winter and summer. In addition, the simulations with small channels exhibit poor thermal performance but better air purification effect, reaching total CADR as high as 69.46 m3 and 67.33 m3 respectively in winter and summer. Meanwhile, the energy consumption and energy saving rate of the DSPVW-PV/PCM is −3.09 kW and 75.7 %, respectively, compared to the SPVW system. This study could contribute to the widespread adoption and application of solar ventilation walls in regions with hot summers and warm winters.

Effects of temperature cycles on human thermal comfort in built environment under summer conditions

Dynamic temperature control strategies are feasible for enhancing energy flexibility and reducing energy consumption in buildings. However, guidelines for designing such dynamic thermal environments are lacking. In this study, 30 participants were recruited to undergo four experimental cycles formed by combining two temperature ranges (25–28 °C and 26–29 °C) and two temperature change rates (3 °C/h and 6 °C/h). Variations in the subjective perception and physiological responses with time were recorded throughout the experiments. The participants reported cooler thermal sensation and better thermal comfort for the same temperature during the ramp-down phase than during the ramp-up phase, which was more pronounced at faster temperature changes. The limits on temperature variations in the current standards underestimate the thermal acceptability of people. Although the temperature cycles exceeded the limits in the standards, sustained thermal comfort and high thermal acceptability were achieved when the temperature changed within 25–28 °C. At a rapid 6 °C/h change rate, the thermal sensation briefly deviated from the comfort zone when Top changed within 26–29 °C, suggesting that the limits should be set relative to the temperature change span. The comfortable temperature ranges for change rates of 3 °C/h and 6 °C/h in summer conditions were 22.8–28.7 °C and 22.8–28.4 °C, respectively, which are broader than the recommended indoor temperature range for summer in the Chinese standard. These findings indicate the potential of temperature variations to extend the thermal comfort zones while consuming less energy without requiring additional cooling devices.

Investigating temperature change rate and pore confinement effect on thermal properties of phase change materials for de-icing and low-temperature applications in cementitious composites

Incorporation techniques of phase change materials (PCM) in cementitious composites have a significant influence on thermal properties. This study investigated the thermal behavior of low-temperature PCM when subjected to varying temperature change rates and pore confinement inside the porous network of lightweight aggregates (LWA) and encapsulation using melamine-formaldehyde-based polymer. Three categories of thermal energy storage (TES) specimens were prepared: (i) Bulk PCM (i.e., liquid PCM), (ii) micro-encapsulated PCM (MPCM), and (iii) four different LWAs infused with PCM (PCM-LWA). The thermal properties of small-scale individual TES specimens were analyzed using a low-temperature differential scanning calorimeter (LT-DSC) to evaluate the effect of ramp rates. Dynamic vapor sorption (DVS) analysis was utilized to characterize the pore structure of LWAs. LT-DSC results show that undercooling of the PCM significantly increases with the rise in ramp rate for all the specimens; temperature change rate affects the nucleation and crystallization growth process during the phase transition. Pore structure characterization of LWAs indicates that the majority of the pores (> 92 %) were larger than 17.3 nm (i.e., macropores). Confined liquid properties are subjected to modification due to interaction with the confining surfaces, as explained by Gibbs-Thomson theory. PCM incorporated in the LWA porous network experienced variable degree of supercooling during phase transition; magnitude of confinement pressure is dependent on the pore diameter, structure, and tortuosity. Experimental evidence suggested that PCM-LWA will exhibit gradual expulsion of enthalpy of fusion over a larger temperature range (i.e., ∼−5 °C to 4.28 °C) in comparison to MPCM (i.e., ∼4.28 °C).

Prediction of Lithium Battery Health State Based on Temperature Rate of Change and Incremental Capacity Change

With the use of Li-ion batteries, Li-ion batteries will experience unavoidable aging, which can cause battery safety issues, performance degradation, and inaccurate SOC estimation, so it is necessary to predict the state of health (SOH) of Li-ion batteries. Existing methods for Li-ion battery state of health assessment mainly focus on parameters such as constant voltage charging time, constant current charging time, and discharging time, with little consideration of the impact of changes in Li-ion battery temperature on the state of health of Li-ion batteries. In this paper, a new prediction method for Li-ion battery health state based on the surface difference temperature (DT), incremental capacity analysis (ICA), and differential voltage analysis (DVA) is proposed. Five health factors are extracted from each of the three curves as input features to the model, respectively, and the weights, thresholds, and number of hidden layers of the Elman neural network are optimized using the Whale of a Whale Algorithm (WOA), which results in an average decrease of 43%, 49%, and 46% in MAE, RMSE, and MAPE compared to the Elman neural network. For the problem where the three predictions depend on different sources, the features of the three curves are fused using the weighted average method and predicted using the WOA–Elman neural network, whose MAE, RMSE, and MAPE are 0.00054, 0.0007897, and 0.06547% on average. The results show that the proposed method has an overall error of less than 2% in SOH prediction, improves the accuracy and robustness of the overall SOH estimation, and reduces the computational burden to some extent.

Seasonal Evolution of Stable Thermal Stratification in Central Area of Lake Ladoga

The complete climatic courses of the parameters of stable thermal stratification for the central part of Lake Ladoga, the largest European lake, are presented on the basis of empirical relationships, taking into account the physical processes governing water temperature variations. For the first time, the seasonal cycle of the surface water temperature, the temperature and the depth of the thermocline, and the hypolimnion temperature are calculated using the vertical profiles of the temperature obtained from the central area of Lake Ladoga. Temperature data are used for the period of in situ observations from 1897 to the present. The proposed functional forms of the temporal temperature cycle and the course of thermocline’s boundaries deepening are useful for examination and simulation of the heat vertical transport from air to water. Approximation curves for the parameters of heating and cooling periods were developed with high significant determination coefficients. Time dependencies of the climatic rates of change in water temperature and the depth of the thermocline boundaries were determined from the onset of stable stratification to its dissipation. The highest rate of water temperature change in the heating stage takes place in late June–early July, which at the water surface, is 0.32 °C/day, while in the thermocline layer, it is 0.18 °C/day. The peak velocity during the cooling stage at the surface occurs in late August–early September and is 0.14 °C/day, whereas in the thermocline, it is 0.08 °C/day and takes place between September and early October. During the period of heating, the deepening parameters of the thermocline layer do not fluctuate very much, only within the range of 0.1–0.3 m/day. During the cooling period, under the influence of free convection, rates increase drastically. The maximum rates of deepening during the period of full autumn mixing reach 1.8 m/day. When the autumn overturn occurs, the epilimnion thickness equals the bottom depth, and the bottom temperature reaches its maximum during the annual cycle. Climatic norms of the stratification parameters against which it is necessary to assess climate change are calculated.

Evaluation of drastic temperature change on temperature stress of asphalt mixture during microwave deicing

Microwave deicing is an efficient and environment-friendly technology for asphalt pavement. Previous studies have shown that silicon carbide can improve the deicing efficiency of pavement, but the influence of drastic temperature change during microwave deicing on the temperature stress and temperature fatigue life is undefined. In this study, the temperature stress during heating and cooling were analysed by numerical simulation, and the mechanism of stress change was discussed. Finally, the temperature fatigue performance of pavement was evaluated. The simulation results showed that an increase in the temperature rising rate did not necessarily increase the temperature stress, and there was no stress accumulation after microwave deicing. The temperature stress was affected by both the temperature change rate and the heat transfer performance, and good heat transfer performance of asphalt mixture could reduce the temperature stress. Besides, the drastic temperature change did not necessarily reduce the temperature fatigue life of pavement.

Rapid threat assessment in the Drosophila thermosensory system

Neurons that participate in sensory processing often display “ON” responses, i.e., fire transiently at the onset of a stimulus. ON transients are widespread, perhaps universal to sensory coding, yet their function is not always well-understood. Here, we show that ON responses in the Drosophila thermosensory system extrapolate the trajectory of temperature change, priming escape behavior if unsafe thermal conditions are imminent. First, we show that second-order thermosensory projection neurons (TPN-IIIs) and their Lateral Horn targets (TLHONs), display ON responses to thermal stimuli, independent of direction of change (heating or cooling) and of absolute temperature. Instead, they track the rate of temperature change, with TLHONs firing exclusively to rapid changes (>0.2 °C/s). Next, we use connectomics to track TLHONs’ output to descending neurons that control walking and escape, and modeling and genetic silencing to demonstrate how ON transients can flexibly amplify aversive responses to small thermal change. Our results suggest that, across sensory systems, ON transients may represent a general mechanism to systematically anticipate and respond to salient or dangerous conditions.

Study on start-up characteristics of a heat pipe cooled reactor coupled with a supercritical CO2 Brayton cycle

The new megawatt nuclear power system coupling a heat pipe cooled reactor with a supercritical CO2 Brayton cycle is considered one of the most promising energy conversion systems for large Unmanned Undersea Vehicles (UUVs). This system combines the characteristics of a heat pipe cooled reactor and a S-CO2 Brayton cycle, such as heat pipe start-up limitations and significant thermal inertia. It is unclear whether existing start-up control strategies for either heat pipe cooled reactors or S-CO2 Brayton cycle are suitable for this new system. Therefore, the start-up characteristics and the control strategies of the new megawatt nuclear power system are investigated in this study. A simulation code is developed for the study of the start-up characteristics of this system, which includes models for the reactor, heat pipes, and the S-CO2 Brayton cycle. The validation of the code is conducted based on the experiments as well as the design values. Good agreement between the calculation results and the experimental values or the design values are obtained. And then, the control scheme and start-up strategy of the new system are proposed. The start-up process is divided into four sub-stages, that is, core start-up from cold to critical state, heat pipes start-up, compressor start-up and turbine preheating, and branch switching. Different control strategies are applied to each sub-stage. The results show that the shaft raising rate of 2000 rpm/min is effective in overcoming expansion resistance without causing excessive overshoot in mass flowrate. This control strategy can achieve stable start-up of the new system without exceeding a temperature change rate of 10 K/min. This research may serve as a reference for the conceptual design of this new megawatt nuclear power system.

Finite element heat transfer analysis in selective laser melting of AlSi10Mg alloy using bi-directional scan strategy: Enhanced thermal conductivity considerations

In the present work, a 3D finite element model was created using the commercial ABAQUS software to analyze the selective laser melting process of AlSi10Mg powder in a bidirectional multi-track, multi-layer configuration. The focus of this investigation was to examine distribution of temperature, melt pool geometry, thermal history, and the temperature change rate. To improve the accuracy of the results, the enhanced thermal conductivity was utilized to incorporate the Marangoni convection effect. The results revealed that, in the initial track, the maximum temperature and dimensions of the melt pool increased, ultimately reaching a plateau as the deposited path extended. However, using a bidirectional scan strategy, the maximum temperature at the second track reached its peak and then stabilized. While the maximum heating and cooling rates in the first track showed a nearly identical trend, both parameters decreased at the beginning of the second track and then began to rise again. It can be attributed to the overlapping of the molten zone between the first and second tracks. With an increase in the number of tracks, the maximum temperature, melt pool width, and depth increased until they reached a steady state, with specific values of 2093 K, 258 μm, and 150 μm, respectively. Introducing more layers initially caused an increase in the maximum temperature and dimensions of the melt pool, which eventually reached a steady-state condition. Finally, temperature distribution of the steady-state simulated melt pool was found to match with thermal behavior and eutectic Si features of the experimental sample.

Controls of thermal response of temperate lakes to atmospheric warming

Atmospheric warming heats lakes, but the causes of variation among basins are poorly understood. Here, multi-decadal profiles of water temperatures, trophic state, and local climate from 345 temperate lakes are combined with data on lake geomorphology and watershed characteristics to identify controls of the relative rates of temperature change in water (WT) and air (AT) during summer. We show that differences in local climate (AT, wind speed, humidity, irradiance), land cover (forest, urban, agriculture), geomorphology (elevation, area/depth ratio), and water transparency explain >30% of the difference in rate of lake heating compared to that of the atmosphere. Importantly, the rate of lake heating slows as air warms (P < 0.001). Clear, cold, and deep lakes, especially at high elevation and in undisturbed catchments, are particularly responsive to changes in atmospheric temperature. We suggest that rates of surface water warming may decline relative to the atmosphere in a warmer future, particularly in sites already experiencing terrestrial development or eutrophication.

Experimental study on heat transfer performance using a hybrid cooling method combined of a flat-plate heat pipe and spray cooling

A hybrid cooling system consists of spray cooling as condensing end and flat-plate heat pipe (FPHP) as heat-transfer medium was previously studied on the effects of the volume flow rate and the inlet temperature. As an extension, this paper using multi-nozzle arrays to promote the forced convection heat transfer and changing the surface roughness of the FPHP to improve the phase change heat transfer. It was found that the impinging energy and drainage channel formed by multi-nozzle arrays were the main reasons for the enhancement in convection region. However, in the phase-change section, a uniform thin liquid film and surface roughness apparently improved the evaporation and nucleate boiling. Relative to our previous study, a maximum heat flux removal was increased from 70 W/cm2 to 90 W/cm2 at surface roughness (Ra = 1.62 μm) with a surface superheat only 4.17℃, the heat transfer coefficient of 21.6 W·cm-2·K-1 and an enhancement of 28.6 % were obtained. Furthermore, the transition temperature and the temperature change rate were studied to explore the vapor flow modes and thermal response characteristics of the FPHP. As the transition temperature Ttr = 251 K, and the Knusden number＜0.01, the FPHP consistently maintained a continuum flow regime during startup, stabilization, and dry-out processes. Impressively, the temperature change rate of the FPHP remained below 0.015℃/s, resulting in a temperature change of only 0.9℃ within one minute. This exceptional temperature stability ensured reliable operation for electronic components.

Scaling procedures in climate science: Using temporal scaling to identify a paleoclimate analogue

Using past episodes of climate change as a source of evidence to inform our projections about contemporary climate change requires establishing the extent to which episodes in the deep past are analogous to the current crisis. However, many scientists claim that contemporary rates of climate change (e.g., rates of carbon emissions or temperature change) are unprecedented, including compared to episodes in the deep past. If so, this would limit the utility of paleoclimate analogues. In this paper, I show how a data adjustment procedure called “temporal scaling,” which must be applied to both contemporary and past rate data, complicates the claim that contemporary rates are truly unprecedented. On top of giving actionable recommendations to scientists, this paper advances the philosophical literature concerning the use of models that are known to be somewhat disanalogous to their target systems.

Heat Transfer in Solid by Using Linear Differential Equation

Abstract: Differential equations are fundamental importance in engineering mathematics because any physical law s and relations appear mathematically in the form of such equations. . The rate of heat conduc- tion in a specified direction is proportional to the temperature gradient,which isthe rate of change in temperature with distance in that direction. In this paper we discussed about first order linear homogeneous equations, first order linear non homogeneous and the application of first order differential equationto heat transfer analysis particularly in heat conduction in solids.

Contrasting effects of different organic amendments on the microbial responses to extreme temperature changes

Soil organic amendments can change microbial communities, potentially impacting their resilience to environmental stresses and, consequently, their transformation of soil carbon and nitrogen. While several studies have investigated the impact of a few organic amendments on microbial resilience to stresses in the form of absolute change in environmental conditions, the potential stress effects of different rates of change have received much less attention. The rate of change in environmental properties such as temperature may induce different microbial stress responses, given the reliance of microbial defensive mechanisms on time-dependent signalling and activation processes. In this research, we explored the relevance of the rate of temperature change as a microbial stressor and evaluated the potential use of organic amendments in steering soil ecological response. We monitored the changes in microbial properties and concentrations of different carbon and nitrogen fractions to temperature change treatments of 2.5 and 30 °C/d after the application of three commonly available rural organic amendments to a podzol soil in a laboratory incubation study. Results showed significant effects of the temperature treatments on bacterial and total microbial DNA concentrations, as well as on dissolvable and insoluble carbon and nitrogen ratios regardless of the organic amendment treatment. Temperature impacts on respiration rates, priming rates and the concentration of soil hot water extractable carbon and nitrogen differed depending on the organic amendment treatment. Results demonstrated that compost-amended soils were least sensitive to the temperature treatments, while grasses and fermented grasses treatments were generally more sensitive while showing opposite responses. Our findings indicate that organic amendments might be utilized to manipulate the impact of environmental stresses on soil carbon and nitrogen concentrations, and highlight the need for future research to investigate the relevant ecological properties and mechanisms.

Cold-Temperature Coding with Bursting and Spiking Based on TRP Channel Dynamics in Drosophila Larva Sensory Neurons.

Temperature sensation involves thermosensitive TRP (thermoTRP) and non-TRP channels. Drosophila larval Class III (CIII) neurons serve as the primary cold nociceptors and express a suite of thermoTRP channels implicated in noxious cold sensation. How CIII neurons code temperature remains unclear. We combined computational and electrophysiological methods to address this question. In electrophysiological experiments, we identified two basic cold-evoked patterns of CIII neurons: bursting and spiking. In response to a fast temperature drop to noxious cold, CIII neurons distinctly mark different phases of the stimulus. Bursts frequently occurred along with the fast temperature drop, forming a peak in the spiking rate and likely coding the high rate of the temperature change. Single spikes dominated at a steady temperature and exhibited frequency adaptation following the peak. When temperature decreased slowly to the same value, mainly spiking activity was observed, with bursts occurring sporadically throughout the stimulation. The spike and the burst frequencies positively correlated with the rate of the temperature drop. Using a computational model, we explain the distinction in the occurrence of the two CIII cold-evoked patterns bursting and spiking using the dynamics of a thermoTRP current. A two-parameter activity map (Temperature, constant TRP current conductance) marks parameters that support silent, spiking, and bursting regimes. Projecting on the map the instantaneous TRP conductance, governed by activation and inactivation processes, reflects temperature coding responses as a path across silent, spiking, or bursting domains on the map. The map sheds light on how various parameter sets for TRP kinetics represent various types of cold-evoked responses. Together, our results indicate that bursting detects the high rate of temperature change, whereas tonic spiking could reflect both the rate of change and magnitude of steady cold temperature.

Data science assisted cohesive finite element modelling of impact behaviour of AP‐HTPB crystal binder composite

AbstractIn this work, the response of an ammonium perchlorate (AP)‐hydroxyl‐terminated polybutadiene (HTPB) composite material under impact loading is presented, utilizing computational cohesive finite element method (CFEM) simulations that are validated with drop hammer experiments. This study examined the impact behaviour of AP crystal sizes between 200 and 400 μm by varying impact velocities between 3 and 10 m/s. Based on the outcome of CFEM simulations, analysis of variance (ANOVA) tests and a response surface method (RSM) were utilized to construct a mathematical model approximating the relationships between simulation inputs and outcomes. Both computational and experimental results show that the local strain rate has a considerable positive correlation with crystal size, and the rate of temperature change has positive correlations with both crystal size and impact velocity. Further, it was observed that stiffness and compression energy are the primary factors to variances in local strain rate and rate of change of temperature. RSM has been found to be an effective tool for modelling impact responses of materials under varying experimental conditions.

Analysis of the Effect of Temperature on the Ultimate Strength of Refractory Materials

The energy efficiency of high-temperature batch aggregates largely depends on the modes of their heating and cooling. The modes of heating and cooling of aggregates in which thermal stress does not exceed the critical values of the ultimate strength of the refractories make it possible to increase their service life. The increase in the service life of refractories will lead to a reduction in the number of lining repairs and a decrease in the specific consumption of refractory materials per ton of technological product. Shorter warm-up and cool-down times result in lower energy consumption. Reducing the time for variable modes for casting ladles increases their turnover (the number of melt discharges into the ladle per day). Increasing ladle turnover not only reduces the number of ladles but also improves the economic performance of the enterprise. The ultimate strength of the refractory material significantly affects the rate of temperature change during heating and cooling of the refractory masonry. The purpose of this research is to study the dependence of the ultimate compression and tensile strengths of chamotte materials of the ShKU brand on temperature. The determination of the compression and tensile strengths was carried out on new samples of refractory materials as well as on samples of refractories that were in operation until the intermediate repair. To determine the ultimate compression strength of chamotte refractories, the standard technique for axial compression of the test specimen until its destruction was used. To determine the ultimate tensile strength, a three-point bending test was used with additional control of the surface temperature of the test sample during the test. The ultimate compression strength of chamotte refractories of the ShKU-32 brand increased for the new refractories by a maximum of 44%. For refractories that were in operation until the intermediate repair, the ultimate compression strength increased by a maximum of 56%. The value of the ultimate tensile strength at elevated temperatures turned out to be higher than the value at a temperature of 20 °C. For new refractories, the maximum ultimate tensile strength is 25% higher than the ultimate tensile strength under normal conditions. For refractories that were in operation until the intermediate repair, the maximum ultimate tensile strength increased by 24%. The obtained results can be used to increase the rate of heating or cooling of linings.

Electrophoretic Transport Through Fibrocartilage Driven by Square and Sawtooth Pulses With Decreased Joule Heating

Measurement of molecular transport through tissues can be performed using gel electrophoresis techniques but is subject to substantial changes of temperature over the course of an experiment due to conversion of electrical to thermal energy. The objective of this study is to mitigate thermal generation and accumulation while determining the electrophoretic mobility of charged molecules within annulus fibrosus cartilage tissue. By using electrical pulses as compared to direct current (DC), less total energy is input and more heat can dissipate in a given amount of time. Temperature measurements confirm that use of DC leads to higher rates of temperature change during electrophoresis, with Joule heating responsible for the thermal rise. The measured electrophoretic mobilities of two small, charged dye molecules are found to be similar among DC, square and sawtooth pulsed electrophoresis. One significant difference occurs between square and sawtooth pulses for the dye that interacts less with the cartilage tissue. Results herein suggest that accurate measurements with reduced temperature changes of thermally-sensitive tissues can be made using pulsed electrophoresis, which can lead to a better understanding of molecular transport under physiological conditions.