The approximation between thermal sensation votes (TSV) and predicted mean vote (PMV): A comparative analysis

The Fanger's predicted mean vote (PMV) model is used to evaluate thermal comfort. However, when PMV is compared to people's real thermal sensations, collected in field studies, some discrepancies are verified. One of the components for the calculation of PMV is clothing surface temperature (t_cl), which can be a factor that contributes towards these discrepancies. The aim of this study was to propose alternative methods for predicted mean vote, seeking to reduce these discrepancies. The mathematical Newton's method was applied to obtaining t_cl values. The PMV₁ was determined by replacing the t_cl values in the traditional equation of PMV as described by ISO 7730 (2005). The second model of thermal prediction, named as PMV₂, was obtained by a multiple linear regression considering the thermal sensation votes, the metabolic rate and the six heat exchange mechanisms. Two groups (welders and army officers) were used to verify the accuracy of the methods used in this research. The results show that both methods were able to describe the thermal sensation votes. For the welder group, both PMV₁ and PMV₂ overestimated the results: when people voted TSV = 0, PMV₁ = 0.64 and PMV₂ = 0.23. In the case of the army officers group, applying PMV₁, when TSV = 0, PMV₁ = 1.47. The application of the multiple regression increased the potential of PMV₂ to obtain responses closer to those provided by the occupants of the thermal environment studied: when TSV = 0, PMV₂ = 0.0068, demonstrating a greater effectiveness of this method.     

Comparative analysis of methods for determining the metabolic rate in order to provide a balance between man and the environment

The incorrect determination of metabolic rate can be linked to discrepancies between the model of the PMV (Predicted Mean Vote) and real thermal sensation collected in field studies. Aiming to improve the correlation of the PMV model and the real thermal sensation, this work established new values for the metabolic rate: one way being called “calculated” using Newton's Method and the other called "measured" using a metabolic analyzer. Welder's activities were evaluated, through the measurements of environmental and personal variables. New values of metabolic rate were determined for this activity. The values found for the calculated form and the measured one were, respectively, 178.63 and 145.46 W/m², different from the range provided by the table of ISO 8996 (2004) for this activity (75–125 W/m²). In order to verify which of the values of the metabolic rate was closer to the real thermal sensation of PMV, a linear regression was made between the PMV and the real thermal sensation in three ways: S × PMV_tabulated (R² = 0.1749), S × PMV_calculated (R ² = 0.7481) and S × PMV_measured (R² = 0.7854). It was found that the values measured by the instrument gave a higher coefficient of determination which was chosen for the correction of the table. The correction of the table provides a value of M_predicted, that is a value of metabolic rate that corrects the values provided by the tables of ISO 8996 (2004), by means of a correction coefficient. For the welder's activities in a metal-mechanics industry, tabulated values can be multiplied by the correction coefficient 1.4648 in order to minimize inaccuracies. The PMV_predicted, obtained through the M_predicted, when related to the actual thermal sensation, provides a coefficient of determination of 0.7511, thereby improving the model of the PMV.     

PMV model is insufficient to capture subjective thermal response from Indians

A controlled laboratory experiment was carried out on forty Indian male college students for evaluating the effect of indoor thermal environment on occupants' response and thermal comfort. During experiment, indoor temperature varied from 21 °C to 33 °C, and the variables like relative humidity, airflow, air temperature and radiant temperature were recorded along with subject's physiological parameters (skin (T_sk) and oral temperature (T_c)) and subjective thermal sensation responses (TSV). From T_sk and T_c, body temperature (T_b) was evaluated. Subjective Thermal Sensation Vote (TSV) was recorded using ASHRAE 7-point scale. In PMV model, Fanger's T_sk equation was used to accommodate adaptive response. Stepwise regression analysis result showed T_b was better predictor of TSV than T_sk and T_c. Regional skin temperature response, suppressed sweating without dipping, lower sweating threshold temperature and higher cutaneous threshold for sweating were observed as thermal adaptive responses. These adaptive responses cannot be considered in PMV model. To incorporate subjective adaptive response, mean skin temperature (T_sk) is considered in dry heat loss calculation. Along with these, PMV-model and other two methodologies are adopted to calculate PMV values and results are compared. However, recent literature is limited to measure the sweat rate in Indians and consideration of constant Ersw in PMV model needs to be corrected. Using measured T_sk in PMV model (Method₁), thermal comfort zone corresponding to 0.5 ≤ PMV ≤ 0.5 was evaluated as (22.46–25.41) °C with neutral temperature of 23.91 °C, similarly while using TSV response, wider comfort zone was estimated as (23.25–26.32) °C with neutral temperature at 24.83 °C, which was further increased to with TSV-PPD_new relation. It was observed that PMV-model overestimated the actual thermal response. Interestingly, these subjects were found to be less sensitive to hot but more sensitive to cold. A new TSV-PPD relation (PPD_new) was obtained from the population distribution of TSV response with an asymmetric distribution of hot-cold thermal sensation response from Indians. The calculations of human thermal stress according to steady state energy balance models used on PMV model seem to be inadequate to evaluate human thermal sensation of Indians.     

Dynamic clothing insulation. Measurements with a thermal manikin operating under the thermal comfort regulation mode

The main objective of the present work is the assessment of the thermal insulation of clothing ensembles, both in static conditions and considering the effect of body movements. The different equations used to calculate the equivalent thermal resistance of the whole body, namely the serial, the global and the parallel methods, are considered and the results are presented and discussed for the basic, the effective and the total clothing insulations. The results show that the dynamic thermal insulation values are always lower than the corresponding static ones. The highest mean relative difference [(static-dynamic)/static] was obtained with the parallel method and the lowest with the serial. For I_cl the mean relative differences varied from 0.5 to 13.4% with the serial method, from 5.6 to 14.6% with the global and from 7.2 to 17.7% with the parallel method. In addition, the dynamic tests presents the higher mean relative differences between the calculation methods. The results also show that the serial method always presents the higher values and the parallel method the lowest ones. The relative differences between the calculation methods {[(serial-global)/global] and [(parallel-global)/global]} were sometimes significant and associated to the non-uniform distribution of the clothing insulation. In fact, the ensembles with the highest thermal insulation values present the highest differences between the calculation methods.     

The asymptotic behaviour,the angles of departure,and the angles of approach,of the characteristic frequency loci

In algebraic function theory, there is a well established method which uses ‘Newton's diagram’ to find the series expansions of an algebraic function q(x) in the neighbourhood of a point x₀ . In this paper it is shown how, for a linear, time-invariant, multi-variable feedback system, this method can be used to find :

(i) the asymptotic behaviour of the characteristic frequency loci (multivariable root loci) ;

(ii) the angles of departure of the characteristic frequency loci from the open-loop poles ; and

(iii) the angles of approach of the characteristic frequency loci to the finite zeros of such a system.     

基于人体热舒适性指标PMV的暖通空调控制器

分析了人类对暖通空调系统的要求,介绍了暖通空调控制的现状,提出了一种新的基于人体热舒适性指标PMV的暖通空调控制器,该控制器能满足人类对暖通空调系统健康、舒适和节能的要求,是一种理想的暖通空调控制器。     

On the behaviour of approximate Newton methods

Newton's method for solving non linear operator equations requests at each step the solution of a linear equation. When these equations are solved only approximately we have a so called Approximate Newton Method (A.N.M.). In this paper we examine the convergence and the order of convergence of A.N.M.'s under Kantorovich type hypotheses, giving criteria for controlling the behaviour of the iterations. Moreover a posteriori error estimates are proposed. The application of the general results to the case of Newton-Iterative methods is illustrated.     

Physiological strains in hot-humid conditions while wearing disposable protective clothing commonly used by the asbestos removal industry

Abstract

The purpose of this study is to investigate workers' responses to work in hot-humid conditions while wearing protective clothing commonly used by the asbestos removal industry, and to evaluate the effects of resting between work bouts in a cool environment on the physiological strain. Seven male students wearing impermeable protective clothing and air masks were exposed to the following conditions for 100 min on separate days: (1) hot conditions (35°C/85%RH), (2) cool conditions (20°C/85%RH), and (3) hot/cool conditions (working in hot conditions and resting in cool conditions). After 12 min rest, the subjects worked on an ergometer (70 Watts) for 18 min. This experimental schedule was repeated three times under each environmental condition. Rectal temperature (T_π), heart rate (HR), sweat rate (SR) and discomfort sensation were recorded. Two of the subjects were not able to complete the experiment in hot conditions. The increases in T_π and HR with time were not found in cool conditions. Although T_π increased in hot/cool conditions, it was almost half of that in hot conditions. Since HR did not return to the pre-work level during recovery in hot conditions, HR during work was accompanied by increases in HR at pre-work. HR during work in hot/cool conditions was higher than that in cool conditions, HR at pre-work, however, was almost the same as that in cool conditions because of rapid recovery. The means of SR in hot and hot/cool conditions were five and four times greater than that in cool conditions, respectively. Discomfort sensation was improved by resting in cool conditions either at rest in cool conditions or during work in hot conditions. The rate of body heat storage that was calculated at the end of each work and recovery period showed that it was positive even in recovery under the hot conditions. It also presented a significant negative phase in recovery under the hot/cool conditions. Thermal stress was linked to work in protective clothing in hot-humid environments. However, the physiological strains were dramatically ameliorated by resting between work periods in a cool environment. The idea of a ‘cool room’ inside the workplace, so to reduce thermal stress, is proposed.     

Stability analysis of wave-crab gaits of a quadruped

Crab walking is as important as forward walking as applied to walking machine control. Crab walking is especially important to a quadruped since a quadruped has a similar leg geometric layout in both longitudinal and lateral directions. In the studies of forward walking gaits, the wave gait was found to be the optimally stable. In this article, the wave gait is applied to the crab walking of a quadruped and it is modified into four types of wave-crab gaits according to the range of crab angle. The stability formulae of these wave-crab gaits are then derived analytically based on the following three stability measurements: stability margin (S_m), body-longitudinal (or lateral) stability margin (S_bl or S_bt) and crab longitudinal stability margin (S_cl). S_m is the true stability index under quasi-static walking condition. However, the equations are more complicated. S_bl (or S_bt) is simpler and can be used as a good approximation of S_m. S_cl was commonly adopted as the stability index in the previous gait studies. Nevertheless, S_cl is found to be misleading for a large portion of crab angle range. The analytical results derived in this paper are useful to the geometric design and to the real-time control of a quadruped.     

室内舒适性指标PMV的区间Ⅱ型T-S模糊建模

预测平均投票值(PMV)是室内热环境的标准化指标,其涉及的数学模型复杂且存在不确定性,不能适应实时控制的需要.同时,传统的采用一个PMV值评价热环境的方法具有局限性,不能反映不同位置人体舒适感的差异.为了处理测量噪声和人体因素带来的不确定性,通过对室内气流和传热计算流体动力学( CFD)模拟数值以准确描述PMV值,建立...     

The structured controllability radius of linear delay systems

In this article, we shall deal with the problem of calculation of the controllability radius of a delay dynamical systems of the form x′(t)?=?A ₀ x(t)?+?A ₁ x(t???h ₁)?+?···?+?A _k x(t???h _k )?+?Bu(t). By using multi-valued linear operators, we are able to derive computable formulas for the controllability radius of a controllable delay system in the case where the system's coefficient matrices are subjected to structured perturbations. Some examples are provided to illustrate the obtained results.     

Newton's method for the Navier-Stokes equations with finite-element initial guess of stokes equations

It is shown that finite element solutions of Stokes equations may be chosen as the initial guess for the quadratic convergence of Newton's algorithm applied to Navier-Stokes equations provided there are sufficiently small mesh size h and the moderate Reynold's number. We provide also a mixed convergence analysis in terms of iterations and finite-error estimates of the initial guess with a regularity estimate and error analysis for each Newton's step.     

Approximate Inverse Preconditioners for the Conjugate Gradient Method

The method of Conjugate Gradients is known to converge for symmetric positive definite systems of equations. This paper applies it to non-symmetric and ill-conditioned matrices. In order to facilitate convergence, an approximate inverse is used to precondition the Conjugate Gradient method. This is achieved by applying Newton's method. Three versions of Newton's method are introduced to compute the approximate inverse. Convergence of each version is compared. Numerical experimentation is done for some known "ill-conditioned" problems.     

Evaluation of the DART 3D model in the thermal domain using satellite/airborne imagery and ground-based measurements

This work provides an evaluation of the discrete anisotropy radiative transfer (DART) three-dimensional (3D) model in assessing the simulation of directional brightness temperatures (T _b) at both sensor and surface levels. Satellite imagery acquired with the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), airborne imagery acquired with the Airborne Hyperspectral Scanner (AHS) sensor and ground-based measurements collected over an agricultural area were used to evaluate the DART model at nadir views. Directional radiometric temperatures measured with a goniometric system at ground level were also used to evaluate modelling results at different view angles. The DART model was evaluated over three homogeneous plots: bare soil (BS), green grass (GG) and sand (NS). The results show good agreement between the simulations and the satellite, airborne and ground-based measurements, with root mean square errors (RMSEs) less than 2.0 K. However, three major discrepancies were found: (1) differences greater than 4.0 K over BS when comparing DART and ASTER, attributed to turbulence-induced temperature fluctuations, (2) higher differences in sensor-level than in surface-level comparisons when using AHS due to thermal heterogeneity of the selected regions of interest in the image and also to differences in atmospheric correction performed over the imagery and the correction included in the DART model, especially for bands located in the lowest atmospheric transmissivity regions and (3) RMSEs greater than 2.0 K when comparing DART results and ground measurements over the NS plot, due to the strong emissivity correction in the 8.0–9.0 μm bands, where the measured emissivity was below 0.75. Despite these discrepancies, we show that the DART model is a useful tool for simulating remotely sensed thermal images over different landscapes. Finally, new versions of this model are continuously being released to solve technical problems and improve the simulation results.     

First-principles calculation of L10 -disorder phase equilibria for Fe–Ni system

By combining Cluster Variation Method with FLAPW electronic structure total energy calculations and the Debye–Grüneisen theory within quasi-harmonic approximation, L1₀-disorder phase equilibria for Fe–Ni system are calculated. The transition temperature, 483 K, determined in the present calculation is lower than that obtained in the previous calculation without thermal vibration effects. The decrease of the transition temperature is ascribed to the enhanced phase stability of a disordered phase due to the thermal softening of a lattice.     

An intelligent HVAC control strategy for supplying comfortable and energy-efficient school environment

In South Korea, school buildings require significant energy inputs for heating and air-conditioning, and the majority of the occupants are adolescent students, whose health and cognitive performance are vulnerable to poor indoor air quality (IAQ) and thermal discomfort. Using field measurements, some previous studies have reported that some Korean schools have poor IAQ and thermal conditions. Thus, it is necessary to develop effective heating, ventilation, and air-conditioning (HVAC) control strategies to improve the indoor environment and reduce energy consumption. Therefore, this study proposes an intelligent HVAC integrated control strategy that can improve indoor environmental quality (IEQ) and reduce energy consumption in school buildings. The proposed strategy utilizes an integrated neural network prediction model for IEQ and a heuristic method that can optimize control objectives (i.e., the predicted mean vote [PMV], carbon dioxide [CO₂], particulate matter with diameters of 10 and 2.5 μm [PM₁₀ and PM_2.5, respectively], and HVAC energy consumption). To evaluate the control performance of the proposed strategy, the present study employs two base algorithms (i.e., a rule-based and a non-adaptive control approach) under non-disturbance and forcing disturbance scenarios. The control failure period for PMV is found to be 1.6420% and 9.4773% of the total occupancy period under the non-disturbance and forcing disturbance scenarios, respectively, while CO₂ control failure does not occur under either scenario. The control failure periods for PM₁₀ and PM_2.5 were 5.1676%, and 7.1844%, respectively, under forcing disturbance. Under the non-disturbance scenario, the proposed strategy consumed 2,467.07 kWh and 870,26 kWh for heating and cooling, respectively, representing 91.1% and 84.08% of that for the rule-based algorithm. The proposed strategy can thus effectively improve the IEQ of a building and has the potential for use in the development of integrated environmental management solutions for buildings.     

一类求解非线性奇异方程组的牛顿改进算法

受一个求解非线性奇异方程组迭代格式的启示,将两种牛顿改进算法推广成一般形式,并将其发展为一类求解具有奇异雅可比矩阵的非线性方程组的牛顿改进算法.首先,描述这类新算法的迭代格式,并导出其收敛阶,该新格式每步迭代仅需计算一次函数值和一次导函数值;然后,对测试函数进行检验,并与牛顿算法及其他奇异牛顿算法进行比较,从而验证该算法的快速收敛性;最后,通过两个实际问题验证所提出算法的有效性.     

Numerical computation of cross‐coupled algebraic Riccati equations related to H2/H∞ control problem for singularly perturbed systems

In this paper, we present a numerical algorithm to the cross‐coupled algebraic Riccati equations(CARE) related to H₂/H_∞ control problems for singularly perturbed systems (SPS) by means of Newton's method. The resulting algorithm can be widely used to solve Nash game problems and robust control problems because the CARE is solvable even if the quadratic term has an indefinite sign. We prove that the resulting iterative algorithm has the property of the quadratic convergence. Using the solution of the CARE, we construct the high‐order approximate H₂/H_∞ controller. Copyright © 2004 John Wiley & Sons, Ltd.     

Effects of heated seat and foot heater on thermal comfort and heater energy consumption in vehicle

Subjective experiments involving 12 different conditions were conducted to investigate the effects of heated seats and foot heaters in vehicles on thermal sensation and thermal comfort. The experimental conditions involved various combinations of the operative temperature in the test room (10 or 20°C), a heated seat (on/off) and a foot heater (room operative temperature +10 or +20°C). The heated seat and foot heater improved the occupant's thermal sensation and comfort in cool environments. The room operative temperature at which the occupants felt a ‘neutral’ overall thermal sensation was decreased by about 3°C by using the heated seat or foot heater and by about 6°C when both devices were used. Moreover, the effects of these devices on vehicle heater energy consumption were investigated using simulations. As a result, it was revealed that heated seats and foot heaters can reduce the total heater energy consumption of vehicles.

Statement of Relevance: Subjective experiments were conducted to investigate the effects of heated seats and foot heaters in vehicles on thermal comfort. The heated seat and foot heater improved the occupant's thermal sensation and comfort in cool environments. These devices can reduce the total heater energy consumption in vehicles.     

On the convergence order of a modified method for simultaneous finding polynomial zeros

Using Newton's corrections and Gauss-Seidel approach, a modification of single-step method [1] for the simultaneous finding all zeros of ann-th degree polynomial is formulated in this paper. It is shown thatR-order of convergence of the presented method is at least 2(1+τ _n ) where τ _n ∈(1,2) is the unique positive zero of the polynomial \(\tilde f_n (\tau ) = \tau ^n - \tau - 1\) . Faster convergence of the modified method in reference to the similar methods is attained without additional calculations. Comparison is performed in the example of an algebraic equation.