Flexible thermocells for utilization of body heat

Plastic thermo-electrochemical ceils （thermocells） involving aqueous potassium ferricyanide/ferrocyanide electrolyte have been investigated as an alternative to conventional thermoelectrics for thermal energy harvesting. Plastic thermocells that consist of all pliable materials such as polyethylene terephthalate （PET）, fabrics, and wires are flexible enough to be wearable on the human body and to be wrapped around cylindrical shapes. The performance of the thermocells is enhanced by incorporating carbon nanotubes into activated carbon textiles, due to improved charge transfer at the interface. In cold weather conditions （a surrounding temperature of 5 ℃）, the thermocell generates a short-circuit current density of 0.39 A/m2 and maximum power density of 0.46 mW/m2 from body heat （temperature of 36℃）. For practical use, we have shown that the thermocell charges up a capacitor when worn on a T-shirt by a person. We also have demonstrated that the electrical energy generated from waste pipe heat using a serial array of the thermocells and voltage converters can power a typical commercial light emitting diode （LED）.

Human-Like Robot Sensing Mediated by Body Heat

This paper presents a novel robotic sensor system that can monitor volatile chemicals and airflow. The system is modelled on characteristics of the human body that are thought to have a significant influence on the human odour and airflow senses. In particular, the effect of buoyant airflow due to body heat acts to gather volatile chemicals over large areas of the human body and carry them to the nose. It is postulated that this effect increases the receptive area for human olfaction. In addition, the interaction between rising air heated by the body and external airflow produces a temperature distribution about head height that can be used to infer airflow direction and magnitude. A heated sensor system was constructed to investigate these effects and the resulting sensor was mounted on a mobile robot. The design of the sensor system is described. Results are presented which demonstrate its ability to measure airflow direction and detect chemical signals over a wider receptive field compared with an unheated sensor.

Multi-objective constructal design for quadrilateral heat generation body based on thermal-entransy theory and NSGA-Ⅱ

Based on thermal-entransy theory, the multi-objective constructal design of quadrilateral heat generation body(HGB) with similar shapes of leaves is studied further. The relationship between the aspect ratio of quadrilateral HGB and average temperature difference based on thermal-entransy dissipation is compared with that between the aspect ratio of quadrilateral HGB and the maximum temperature difference(MTD). The relationship between a composite function, consisting of linear weighting sum of the average temperature difference and MTD, and aspect ratio is obtained, and the optimal aspect ratios under minimum composite function with different weighting coefficients are obtained. Using the NSGA-Ⅱ algorithm, the Pareto frontier containing a series of compromise results of average temperature difference and MTD is obtained, and optimization results are compared using the deviation index. There is no aspect ratio to make both MTD and average temperature difference reach the minimum, and the optimal aspect ratio under the minimum MTD is smaller than that under the minimum average temperature difference. The optimal aspect ratio is obtained by making the composite function reach the minimum, and the optimal aspect ratios obtained by minimizing the composite function with different weighting coefficients are different. Compared with the construct of the initial design, the value of the composite function with optimal construct decreases by 1.9%, and the aspect ratio of the quadrilateral HGB decreases by 9.1%. The average temperature difference with the optimal construct increases by 2.1%, and the MTD with the optimal construct decreases by 5.6%. The deviation index under multi-objective optimization is smaller than that under single-objective optimization, and the obtained construct has better comprehensive thermal conductivity. Compared with TOPSIS and LINMAP decision-making methods, the average temperature difference with composite function optimization increases by 0.55% and 0.62% respectively, but the MTD with composite function optimization decreases by 0.84% and 0.96%.

Technological,environmental and biological factors:referent variance values for infrared imaging of the bovine

Background： Despite its variety of potential applications, the wide implementation of infrared technology in cattle production faces technical, environmental and biological challenges similar to other indicators of metabolic state. Nine trials, divided into three classes （technological, environmental and biological factors） were conducted to illustrate the influence of these factors on body surface temperature assessed through infrared imaging. Results： Evaluation of technological factors indicated the following： measurements of body temperatures were strongly repeatable when taken within ]0 s; appropriateness of differing infrared camera technologies was influenced by distance to the target; and results were consistent when analysis of thermographs was compared between judges. Evaluation of environmental factors illustrated that wind and debris caused decreases in body surface temperatures without affecting metabolic rate; additionally, body surface temperature increased due to sunlight but returned to baseline values within minutes of shade exposure. Examination/investigation/exploration of animal factors demonstrated that exercise caused an increase in body surface temperature and metabolic rate. Administration of sedative and anti-sedative caused changes on body surface temperature and metabolic rate, and during late pregnancy a foetal thermal imprint was visible through abdominal infrared imaging. Conclusion： The above factors should be considered in order to standardize operational procedures for taking thermographs, thereby optimizing the use of such technology in cattle operations.

NUMERICAL SIMULATIONS OF A CENTERED CONDUCTING BODY ON NATURAL CONVECTION AND HEAT TRANSFER IN AN ENCLOSURE

Numerical simulations are performed for laminar natural convection heat transfer from a centered conducting body enclosed in a square cavity. A high accuracy un steady numerical method is used, combining the unique condition of the pressure, the convergent solutions and the streamfunction value of the inside heat conducting body are given simultaneously. Two examples are simulated with this numerical method and compared with the experimental results. The results of the numerical solutions are consistent with the experimental results. It shows that the numerical method is valid and feasible.

Highly stretchable double-network gel electrolytes integrated with textile electrodes for wearable thermo-electrochemical cells

Thermo-electrochemical cells(TECs)provide a new potential for self-powered devices by converting heat energy into electricity.However,challenges still remain in the fabrication of flexible and tough gel electrolytes and their compat-ibility with redox actives;otherwise,contact problems exist between electrolytes and electrodes during stretching or twisting.Here,a novel robust and neutral hydrogel with outstanding stretchability was developed via double-network of crosslinked carboxymethyl chitosan and polyacrylamide,which accommodated both n-type(Fe^(2+)/Fe^(3+))and p-type([Fe(CN)_(6)]^(3-)/[Fe(CN)_(6)]^(4-))redox couples and maintained stretchability(>300%)and recoverability(95%compression).Moreover,poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)textile elec-trodes with porous structure are integrated into gel electrolytes that avoid contact issues and effectively boost the P_(max) of n-and p-type thermocell by 76%and 26%,respectively.The optimized thermocell exhibits a quick current density response and is continually fully operational under deformations,which satisfies the working conditions of wearable devices.Multiple thermocells(four pairs)are effectively connected in alternating single n-and p-type cells in series and out-putted nearly 74.3 mV atΔT=10℃.The wearable device is manufactured into a soft-pack thermocells to successfully harvest human body heat and illuminate an LED,demonstrating the potential of the actual application of the thermocell devices.

High-sensitivity self-powered temperature/pressure sensor based on flexible Bi-Te thermoelectric film and porous microconed elastomer

Electronic skins are artificial skin-type multifunctional sensors,which hold great potentials in intelligent robotics,limb prostheses and human health monitoring.However,it is a great challenge to independently and accurately read various physical signals without power supplies.Here,a self-powered flexible temperature-pressure bimodal sensor based on high-performance thermoelectric films and porous microconed conductive elastic materials is presented.Through introducing flexible heat-sink design and harvesting body heat energy,the thin-film thermoelectric device could not only precisely sense temperature signal but also drive the pressure sensor for detecting external tactile stimulus.The integration of Bi-Te based thermoelectric film with high stability in wide temperature range enables the sensor to sense the ambient temperature with high resolution(<0.1 K)as well as excellent sensitivity(3.77 mV K^(-1)).Meanwhile,the porous microconed elastomer responds to pressure variation with low-pressure detection(16 Pa)and a high sensitivity of 37 kPa^(-1).Furthermore,the bimodal sensor could accurately and simultaneously monitor human wrist pulse and body temperature in real time,which demonstrates promising applications in self-powered electronic skins for human health monitoring systems.

Thermal design for the high-power LED lamp

This paper summarizes different kinds of heat sinks on the market for high power LED lamps. Analysis is made on the thermal model of LED, PCB and heat sink separately with a simplified mode provided. Two examples of simulation are illustrated as a demonstration for the thermal simulation as guidance for LED lamp design.

Temperature Distributions in Power Series， Visualization and Measurement of a Thermal Wake

The present paper derived temperature distributions in power series in a steady laminar wake behinda slender streamlined heated body of revolution. The temperature distribution of the wake behind thebody from = 2 to 70 were fully explored using a recirculating water channel. The thermal wakepatterns behind the body were visualized with the aid of infrared pictures and H2 bubbles.