Time-temperature Thresholds and Safety Factors for Thermal Hazards from Radiofrequency Energy above 6 GHz

This article addresses the process to optimally select safety factors and characteristic values for the Eurocodes. Five amendments to the present codes are proposed: (1) The load factors are fixed, γG = γQ, by making the characteristic load of the variable load changeable, it simplifies the codes and lessens the calculation work. (2) Currently, the characteristic load of the variable load is the same for all variable loads. It creates excess safety and material waste for the variable loads with low variation. This deficiency can be avoided by applying the same amendment as above. (3) Various materials fit with different accuracy in the reliability model. This article explains two options to reduce this difficulty. (4) A method to avoid rounding errors in the safety factors is explained. (5) The current safety factors are usually set by minimizing the reliability indexes regarding the target when the obtained codes include considerable safe and unsafe design cases with the variability ratio (high reliability/low) of about 1.4. The proposed three code models match the target β50 = 3.2 with high accuracy, no unsafe design cases and insignificant safe design cases with the variability ratio 1.07, 1.03 and 1.04.

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Analytical solution of one-dimensional Pennes’ bioheat equation

Open Physics ◽

10.1515/phys-2020-0197 ◽

2020 ◽

Vol 18 (1) ◽

pp. 1084-1092

Author(s):

Hongyun Wang ◽

Wesley A. Burgei ◽

Hong Zhou

Keyword(s):

Analytical Solution ◽

Radiofrequency Energy ◽

Bioheat Equation ◽

Surface Cooling ◽

One Dimensional ◽

The Fourier Transform ◽

The One ◽

Parameter Values ◽

Mathematical Derivation ◽

Effect Of Surface

Abstract Pennes’ bioheat equation is the most widely used thermal model for studying heat transfer in biological systems exposed to radiofrequency energy. In their article, “Effect of Surface Cooling and Blood Flow on the Microwave Heating of Tissue,” Foster et al. published an analytical solution to the one-dimensional (1-D) problem, obtained using the Fourier transform. However, their article did not offer any details of the derivation. In this work, we revisit the 1-D problem and provide a comprehensive mathematical derivation of an analytical solution. Our result corrects an error in Foster’s solution which might be a typo in their article. Unlike Foster et al., we integrate the partial differential equation directly. The expression of solution has several apparent singularities for certain parameter values where the physical problem is not expected to be singular. We show that all these singularities are removable, and we derive alternative non-singular formulas. Finally, we extend our analysis to write out an analytical solution of the 1-D bioheat equation for the case of multiple electromagnetic heating pulses.

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Assessment of the thermal hazards and oxidization mechanism of coloured corn starch dust by TG–FTIR

Journal of Loss Prevention in the Process Industries ◽

10.1016/j.jlp.2020.104380 ◽

2021 ◽

Vol 69 ◽

pp. 104380

Author(s):

Rui Liang ◽

Qiuyue Liang ◽

Zhenbao Li ◽

Qingyun Zhou ◽

Lei Li ◽

...

Keyword(s):

Corn Starch ◽

Thermal Hazards

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Analysis of the Safety Factors of Municipal Road Undercrossing Existing Bridge Based on Fuzzy Analytic Hierarchy Process Methods

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/03611981211031887 ◽

2021 ◽

pp. 036119812110318

Author(s):

Yonghong Yang ◽

Yu Chen ◽

Zude Tang

Keyword(s):

Safety Assessment ◽

Evaluation Method ◽

Comprehensive Evaluation ◽

Safety Evaluation ◽

Safety Factors ◽

Analytic Hierarchy ◽

Road Engineering ◽

Existing Bridges ◽

Hierarchy Process ◽

Engineering Projects

Increasing traffic volume and insufficient road lanes often require municipal roads to be reconstructed and expanded. Where a road passes under a bridge, the reconstruction and expansion project will inevitably have an impact on the bridge. To evaluate the safety impact of road engineering projects on bridges, this paper evaluates the safety of the roads and ancillary facilities of highway bridges involved in municipal road engineering projects. Based on a comprehensive analysis of the safety factors of municipal roads undercrossing existing bridges, a fuzzy comprehensive analytic hierarchy process (AHP) evaluation method for the influence of road construction on the safety of existing bridges is proposed. First, AHP is used to select 11 evaluation factors. Second, the target layer, criterion layer, and index layer of evaluation factors are established, then a safety evaluation factor system is formed. The three-scale AHP model is used to determine the weight of assessment indexes. Third, through the fuzzy comprehensive AHP evaluation model, the fuzzy hierarchical comprehensive evaluation is carried out for the safety assessment index system. Finally, the fuzzy comprehensive evaluation method is applied to the engineering example of a municipal road undercrossing an existing expressway bridge. The comprehensive safety evaluation of the existing bridge reflects the practicability and feasibility of the method. It is expected that, with further development, the method will improve the decision-making process in bridge safety assessment systems.

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