Users’ Thermal Response to a Simulated Tablet Computer Surface

2015 ◽  
Author(s):  
Han Zhang ◽  
Alan Hedge ◽  
Beiyuan Guo
Keyword(s):  
Surface Temperature ◽  
Electronic Device ◽  
Thermal Sensation ◽  
Thermal Response ◽  
Heating Surface ◽  
Lower Surface ◽  
Design Guidelines ◽  
Tablet Computer ◽  
Thermal Discomfort ◽  
Computer Controlled

It has been reported that tablet computer surface temperatures can rise from room temperature up to 47°C. Holding a warm or hot computer surface might cause user’s thermal discomfort and possibly skin burns. The use of a tablet often requires holding the device for prolonged time with multiple fingers and palm areas in contact with the tablet lower surface. Previous research has not tested whole finger/palm thermal sensation at a specific surface temperature in a moderate environmental heat range. The current research investigates user’s thermal sensations on the palm and fingers, in response to warm/heat stimuli in a tablet size device with a longer contact duration than used in previous studies, to provide ergonomic design guidelines for electronic device designers and manufacturers. A tablet-size heating surface was developed comprising of nine rectangular aluminum heating pads connected with computer-controlled heaters and thermal sensors. Participants were asked to report their finger/palm thermal sensation and comfort every 45 seconds when they held the prototype for 90 seconds. Results showed a positive linear relationship between surface temperature and user’s thermal sensation and thermal discomfort. Duration of holding the prototype had no significant effect on user’s thermal comfort, but it did significantly affect thermal sensation ratings.

Surface and Indoor Temperature Effects on User Thermal Responses to Holding a Simulated Tablet Computer

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Han Zhang ◽  
Alan Hedge ◽  
Beiyuan Guo
Keyword(s):  
Surface Temperature ◽  
Thermal Comfort ◽  
Ambient Temperature ◽  
Heat Dissipation ◽  
Thermal Sensation ◽  
Lower Surface ◽  
Tablet Computer ◽  
Ambient Temperatures ◽  
Surface Temperatures ◽  
Series Of Experiments

A series of experiments was conducted to investigate participant thermal responses to different surface temperatures, from 34 to 44 °C, for a simulated tablet computer in different ambient temperatures (13 °C, 23 °C, and 33 °C). Two subjective measures, thermal sensations and thermal comfort, were reported by the participants. Within the same ambient temperature, participants' thermal sensation and discomfort scores were positively correlated with the increase of surface temperature (higher surface temperatures gave warmer sensations). Thermal comfort also decreases with the increase of surface temperature in the tested range. In addition, ambient temperature moderated the effect of surface temperature on participants' thermal sensation scores. The higher surface temperature of 44 °C was rated warmer at 33 °C than 13 °C, but lower surface temperatures (34–38 °C) were rated less warm at 33 °C than 13 °C. On the other hand, all the surface temperatures were perceived less uncomfortable in an environment at 13 °C environment than at 33 °C. The findings can be used to set limits for future tablet computer heat dissipation designs to improve user's thermal experiences.

The effect of temperature change rate on user thermal sensation and its implication for tablet computer heat dissipation design

2016 ◽  
Vol 60 (1) ◽  
pp. 785-789 ◽  
Author(s):  
Han Zhang ◽  
Alan Hedge
Keyword(s):  
Surface Temperature ◽  
Temperature Change ◽  
Heat Dissipation ◽  
Thermal Sensation ◽  
Heating Surface ◽  
Rate Of Change ◽  
Effect Of Temperature ◽  
Tablet Computer ◽  
Change Rate ◽  
Temperature Change Rate

Past research has shown that the rate of change of skin surface temperature can affect thermal sensation. This study investigated users’ thermal responses to a tablet heating surface with different heat pads and different temperature change rates. The test conditions included: A. keeping the surface at a constant 42°C, B. increasing the surface temperature from 38°C to 42°C at a rate of 0.02°C/s in progressive intervals, C. increasing the temperature at 0.15°C/s in progressive intervals, and D. Heating two left and right side pads alternately from 38°C to 42°C at 0.15°C/s in progressive intervals. Overall results showed the lowest temperature change rate of 0.02°C/s was most preferred in terms of thermal comfort. The findings suggest a potential to improve user thermal experience by dissipating tablet computer heat at a lower temperature change rate, or by alternating the dissipation areas.

scholarly journals Thermal response of heat-resistant layer with pyrolysis

2012 ◽  
Vol 16 (1) ◽  
pp. 69-78 ◽  
Author(s):  
Haiming Huang ◽  
Xu Xiaoliang ◽  
Guo Huang ◽  
Zimao Zhang
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Phase Transitions ◽  
Surface Temperature ◽  
Thermal Response ◽  
Heating Surface ◽  
Matrix Composites ◽  
Heat Resistant ◽  
High Silica ◽  
Resistant Layer

A model is developed for analyzing the thermal response of the heat-resistant layer composed of high silica fiber reinforced phenolic matrix composites(SiO2/P) and aluminum, in which pyrolysis and phase transitions are exsited, such as melt, vaporization and sublimation. Based on this model, the thermal response of the heat-resistant layer with different SiO2/P thickness is calculated under a heat flux by using FORTRAN codes. As indicated in the results, the slope of temperature gets a sudden decline at the pyrolysis interface, which is due to the latent heat of pyrolysis; the thickness of heat-resistant layer has little influence on the heating-surface temperature, however, the back temperature may increase with the decreasing thickness; and the thermal conductivity of carbonized layer is very important to thermal response.

Study on Thermal Environment of Sports Field in Different Materials

2013 ◽  
Vol 361-363 ◽  
pp. 538-541
Author(s):  
Yong Qiang Xiao ◽  
Ying Xue Cao
Keyword(s):  
Surface Temperature ◽  
Air Temperature ◽  
Thermal Environment ◽  
Thermal Sensation ◽  
Early Summer ◽  
Artificial Turf ◽  
Environmental Characteristics ◽  
Thermal Discomfort ◽  
Instrumental Measurement ◽  
Cooling Methods

Natural lawn and artificial turf, which have a great difference on practical function and thermal environment characteristics, are widely used in sports field. In order to obtain the quantitative differences on thermal environment in summer, instrumental measurement and questionnaires are used in this paper to investigate the thermal environmental characteristics of natural lawn and artificial turf, respectively. Meanwhile human thermal sensation in the two lawns was also evaluated. The results show that the foliar surface temperature and mean air temperature in artificial turf is significantly higher than that of natural lawn in early summer. Due to thermal discomfort and the potential hurt for athletes on artificial turf field, cooling methods such as sprinkle are recommended.

The Influence of Micro Scale Ratchet Depth on the Motion of Leidenfrost Drop

2015 ◽  
Author(s):  
Jeong Tae Ok ◽  
Sunggook Park
Keyword(s):  
Surface Temperature ◽  
Water Drop ◽  
Lower Surface ◽  
Driving Mechanism ◽  
Entire Surface ◽  
Depth Effect ◽  
Micro Scale ◽  
Temperature Range ◽  
Aspect Ratios ◽  
Surface Temperatures

The influence of ratchet depth on the motion of Leidenfrost water drop was investigated as a continuous effort to reveal the driving mechanism. Continuous directional rebounding behavior of the drop was observed only at below 200°C on both micro ratchets with two different depth-to-period aspect ratios (1:5 and 1:10) and sharp ridges. Overall, the shallow ratchets generated more efficient drop mobility in the entire surface temperature range of 193–299°C due to the increased area between the bottom of the drop and the ratchet surface, caused by the geometrical benefit. However, the depth effect was only critical at relatively lower surface temperatures.

scholarly journals A COMBINED USE OF FDM AND DOE METHOD TO DERIVE A NEW TRANSIENT SIMPLIFIED SEMI-ANALYTICAL MODEL: A CASE STUDY OF ANHYDRITE RADIANT SLAB

2020 ◽  
Vol 330 ◽  
pp. 01002
Author(s):  
Abdelatif Merabtine ◽  
Abdelhamid Kheiri ◽  
Salim Mokraoui
Keyword(s):  
Surface Temperature ◽  
Analytical Model ◽  
Numerical Models ◽  
Thermal Response ◽  
Sensitivity Study ◽  
Conventional Heating ◽  
Heating Systems ◽  
Combined Use ◽  
Scale Test ◽  
Radiant Floor Heating

Radiant floor heating systems (FHS) are considered as reliable heating systems since they ensure maintaining inside air temperature and reduce its fluctuations more efficiently than conventional heating systems. The presented study investigates the dynamic thermal response of an experimental FHS equipped with an anhydrite radiant slab. A new simplified model based on an analytical correlation is proposed to evaluate the heating radiant slab surface temperature and examine its thermal behavior under dynamic conditions. In order the validate the developed analytical model, an experimental scenario, under transient conditions, was performed in a monitored full-scale test cell. 2D and 3D numerical models were also developed to evaluate the accuracy of the analytical model. The method of Design of Experiments (DoE) was used to both derive meta-models, to analytically estimate the surface temperature, and perform a sensitivity study.

Responses of Motor-Sport Athletes to V8 Supercar Racing in Hot Conditions

2007 ◽  
Vol 2 (2) ◽  
pp. 182-191 ◽  
Author(s):  
Matt B. Brearley ◽  
James P. Finn
Keyword(s):  
Perceived Exertion ◽  
Thermal Sensation ◽  
Sweat Rate ◽  
Thermal Strain ◽  
Body Core Temperature ◽  
Hydration Status ◽  
Borg Scale ◽  
Thermal Discomfort ◽  
Body Core ◽  
Cardiovascular Strain

Background:Despite the thermal challenge of demanding workloads performed in high cabin temperatures while wearing heavy heat-retardant clothing, information on physiological responses to racing V8 Supercars in hot conditions is not readily available.Purpose:To describe the thermal, cardiovascular, and perceptual strain on V8 Supercar drivers competing in hot conditions.Methods:Thermal strain was indicated by body-core temperature using an ingested thermosensitive pill. Cardiovascular strain was assessed from heart rate, hydration status, and sweat rate. Perceptual strain was estimated from self-rated thermal sensation, thermal discomfort (modified Gagge scales), perceived exertion (Borg scale), and perceptual strain index.Results:Prerace body-core temperatures were (mean ± SD) 37.7°C ± 0.4°C (range 37.0°C to 38.2°C), rising to 39.0°C ± 0.4°C (range 38.4°C to 39.7°C) postrace. Driver heart rates were >160 and >170 beats/min for 85.3% and 46.7% of racing, respectively. Sweat rates were 1.06 ± 0.12 L/h or 13.4 ± 1.2 mL · kg−1 · h−1, and postrace dehydration was 0.6% ± 0.6% of prerace body mass. Drivers rated thermal sensation as hot (10.3 ± 0.9), thermal discomfort as uncomfortable (3.1 ± 1.0), and perceived exertion as very hard to very, very hard (8.7 ± 1.7) after the races. Overall physiological and perceptual strain were 7.4 ± 1.0 and 7.1 ± 1.2, respectively.Conclusions:Despite the use of cooling, V8 Supercar drivers endure thermal, cardiovascular, and perceptual strain during brief driving bouts in hot conditions.

scholarly journals Thermal Comfort-Based Personalized Models with Non-Intrusive Sensing Technique in Office Buildings

2019 ◽  
Vol 9 (9) ◽  
pp. 1768 ◽  
Author(s):  
Siliang Lu ◽  
Weilong Wang ◽  
Shihan Wang ◽  
Erica Cochran Hameen
Keyword(s):  
Surface Temperature ◽  
Skin Temperature ◽  
Thermal Environment ◽  
Thermal Sensation ◽  
Correlation Coefficients ◽  
Hvac Systems ◽  
Recall Score ◽  
Support Vector ◽  
Linear Kernel ◽  
Related Factors

Heating, ventilation and air-conditioning (HVAC) systems play a key role in shaping the built environment. However, centralized HVAC systems cannot guarantee the provision of a comfortable thermal environment for everyone. Therefore, a personalized HVAC system that aims to adapt thermal preferences has drawn much more attention. Meanwhile, occupant-related factors like skin temperature have not had standardized measurement methods. Therefore, this paper proposes to use infrared thermography to develop individual thermal models to predict thermal sensations using three different feature sets with the random forest (RF) and support vector machine (SVM). The results have shown the correlation coefficients between clothing surface temperature and thermal sensation are 11% and 3% higher than those between skin temperature and thermal sensation of two subjects, respectively. With cross-validation, SVM with a linear kernel and penalty number of 1, as well as RF with 50 trees and the maximum tree depth of 3 were selected as the model configurations. As a result, the model trained with the feature set, consisting of indoor air temperature, relative humidity, skin temperature and clothing surface temperature, and with linear kernel SVM has achieved 100% recall score on test data of female subjects and 95% recall score on that of male subjects.

scholarly journals Peculiarities in Leidenfrost water droplet evaporation

2020 ◽  
Author(s):  
Tadeusz Orzechowski
Keyword(s):  
Surface Temperature ◽  
Orthogonal Projection ◽  
Water Droplet ◽  
Linear Time ◽  
Heating Surface ◽  
Droplet Evaporation ◽  
Measuring System ◽  
Main Element ◽  
Bottom Surface ◽  
Good Representation

Abstract The investigations involved a large water droplet deposited on the heating surface, the temperature of which was higher than the Leidenfrost point. The main element of the experimental setup was the heating cylinder with K-type shielded thermocouple located in its centre just below the surface. The measuring system was located on highly sensitive scales. The analysis of the droplet behaviour in time was conducted based on measured droplet mass changes over time and also photographic data recorded with high resolution digital camera. The energy balance equation is given for the assumption that evaporation from the droplet upper surface is small compared with the amount of heat dissipated from the bottom surface. The formula for the heat transfer coefficient depends on two slope values and an orthogonal projection of the drop onto the heating surface. The slopes are estimated based on the droplet diameter linear time dependence and mass versus the contact zone relationship. The solution provides a good representation of droplet evaporation under Leidenfrost conditions. The investigations, reported in the study, which concern water droplet at atmospheric pressure deposited on a hot surface with the temperature higher than the Leidenfrost point, indicate the following regularities: droplet orthogonal projection onto the heating surface changes linearly with the droplet mass, evaporation of the same amount of mass decreases linearly with an increase in the heating surface temperature, slope of the graph showing mass loss versus the heating surface temperature successively decreases.

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