An individualized and multi-segmental bioheat model for predicting local conditions of the human body under various thermal environments.

Thermoregulatory bioheat models have attracted the attention of researchers due to their conformity with the basis of human thermal perception. For this reason, various models have been presented, such as simplified thermoregulatory bioheat (STB), individualized thermoregulatory bioheat (ITB), and multi-segmental thermoregulatory bioheat (MSTB). In the present study and based upon previous models, an individual multi-segment thermoregulatory bioheat (IMTB) model has been introduced. In this model, the body is subdivided into 17 segments and 3 layers, with the blood circulatory system consisting of arteries, veins, and superficial veins. Also, IMTB can evaluate the individual parameters effects (such as height, weight, gender, and age) on physiological parameters and active/passive systems. Finally, this new model was evaluated in human thermal response predictions over a wide range of transient and steady-state environmental conditions (5.0< Tair(°C) <50.0, 31.0 < RH (%)<70.0) and various individual characteristics (male and female, 20 < age (years) < 69, 50

Assessment of overall body thermal sensation based on the thermal response of local cutaneous thermoreceptors.

In non-uniform environments, different body parts may experience different ranges of physical/environmental parameters. Therefore, to assess the overall thermal sensation in non-uniform environments, the local temperature/thermal sensation of various body parts should be calculated. The local temperature/thermal sensation based on cutaneous thermoreceptor (TRs) responses has been evaluated using MSTB (Multi-Segmental Thermoregulatory Bioheat) model and LTRESP (Local Thermal Response) index in our recent studies. In the present study, a new combined method was proposed to evaluate the overall thermal sensation considering the effects of local sensations of various body segments. In this new method, the local sensations predicted by LTRESP index were defined as the input data for UCB model to predict the overall thermal sensation. So, there was no need to feed it with experimental data to assess the whole-body thermal sensation. Meanwhile, in this method, the overall thermal sensation was predicted taking into account the cutaneous TRs thermal responses. The results indicated that the new combined method could evaluate the overall thermal sensation with a reasonable accuracy under different environmental conditions. Thus, the new method could be practical for predicting the overall thermal sensation in both uniform and non-uniform thermal environments.

A new local thermal bioheat model for predicting the temperature of skin thermoreceptors of individual body tissues.

Under non-uniform environments, the human body thermal perception depends on the thermal responses of cutaneous thermoreceptors (TRs) in different body parts. However, skin TRs thermal response includes static and dynamic parts depending on TRs temperature and its change rate, respectively. Thus, it is necessary to evaluate the time-dependent temperatures of cutaneous TRs in different body parts. The Pennes equation is one of the most important bioheat equations for computing the temperature of biological bodies, but, it has been used for evaluating the mean temperature of the whole body, considering average properties for all body parts. In the present study, the Pennes equation was solved for 16 body parts by considering appropriate thermal/physiological properties for each segment. In addition, a controlling system was added to the Pennes equation by applying the thermoregulatory mechanisms of 65-node Tanabe (65MN) model. The time-dependent skin temperatures of the 16 body segments were obtained by solving the localized thermoregulatory bioheat equation. The validation of the present model was carried out using published experimental data and a good agreement was found.

A new local index for predicting local thermal response of individual body segments.

Physiologically, the thermal sensation/perception of human body is related to the response of cutaneous thermoreceptors (TRs) to the environment. However, the thermal response of skin warm and cold TRs is a function of two important factors: TRs temperatures and their time derivative at the subcutaneous locations of TRs. The available thermal models based on TRs response consider the same sensitivity for all thermal receptors of body. Thus, they estimate an average value of thermal response for whole body TRs. Therefore, considering the physiological thermal perception of humans, this study has presented a local thermal response index for estimating local sensation of different body segments based on local thermal response of individual TRs. Further, this index has used the ASHRAE thermal sensation scales to express the TRs thermal responses. Also, the new multi-segmental thermoregulatory bioheat model (MSTB) is utilized to calculate the individual TRs temperature. Finally, the predicted local thermal sensation by the new local index has been compared with published measured data under uniform/non-uniform thermal conditions. The results show that the local thermal sensation of individual body parts could be evaluated by the new local predictive index (LTRESP) with reasonable accuracy under various thermal conditions.

Effect of resilient architecture in an ancient windmill in the Sistan region on natural ventilation enhancement.

Over centuries different elements have been developed in architectures for ensuring adequate natural ventilation in residential units. This study assesses the different components of an ancient windmill in Sistan, Iran, on the structure's indoor air quality (IAQ) enhancement. Several climatic scenarios have been defined by the wind analysis of Sistan meteorological data and analyzed by CFD. The site measurements confirm the accuracy of the simulation results. In the windmill, two deflectors facing the prevailing wind are the significant elements which, in addition to directing wind toward the entrance, could form vortices near the east and west openings leading to suction ventilation. Alteration of the wind speed and angle from 10 to 15 m/s and 30° to 17° would increase the air change per hour (ACH) by 150% and 110%, respectively. Meanwhile, the ACHs were higher than the ASHRAE desired level (ACH > 0.35).