Contact Heat Evoked Potentials in China: Normal Values and Reproducibility

Background: Contact heat evoked potentials (CHEPs) is used to diagnose small fiber neuropathy (SFN). We established the normal values of CHEPs parameters in Chinese adults, optimized the test technique, and determined its reproducibility.Methods: We recruited 151 healthy adults (80 men; mean age, 37 ± 14 years). CHEPs was performed on the right forearm to determine the optimal number of stimuli, and then conducted at different sites to establish normal values, determine the effects of demographic characteristics and baseline temperature, and assess the short- (30 min) and long-term (1 year) reproducibility. N2 latency/height varied with age and sex, while P2 latency/height and N2–P2 amplitude varied with age. The optimal number of stimuli was three.Results: N2 latency/height (t = 5.45, P < 0.001) and P2 latency/height (χ2 = −4.06, P < 0.001) decreased and N2–P2 amplitude (t = −5.01, P < 0.001) and visual analog scale score (χ2 = −5.84, P < 0.001) increased with increased baseline temperature (35 vs. 32°C). CHEPs parameters did not differ with time (baseline vs. 30 min vs. 1 year).Conclusion: We established normal CHEPs values in Chinese adults. We found that CHEPs parameters changed with baseline temperature and that the short- and long-term test reproducibility were satisfactory.

A simplified mathematical model for total temperature rise calculation in non-oriented silicon steel cold rolling deformation zone

In tandem cold rolling, the control of the temperature of high-grade non-oriented silicon steel is a difficult problem for its large deformation resistance and the preheating procedure before rolling. And it is complicated to calculate the total temperature rise of rolling deformation zone due to the comprehensive influence of the plastic deformation heat, the friction heat and the contact heat loss. So, to precisely calculate the total temperature rise, firstly, based on the four classical cold rolling force formulas, the initial total temperature rise calculation models are established correspondingly by theoretically analyzing the temperature rise of deformation heat, the temperature rise of friction heat and the temperature drop of contact heat loss; then, the model based on the improved Lian rolling force formula is adopted, which leads to calculated best matching the measured temperature; finally, considering the complex formula calculation of the initial model, based on the influences of different rolling parameters on the total temperature rise, a simplified model for convenient calculation is proposed by the nonlinear regression analysis of the initial model calculation results and main rolling parameters, which is convenient for the actual application by the field technicians.

Non-contact heat transfer models identification for laser hyperthermia of semi-transparent materials

The identification of mathematical models of heat transfer traditionally involves the installation of temperature sensors inside the sample under study and registration of the response to external thermal effects. In cases where the use of contact methods for measuring temperature is impossible, it is necessary to develop new approaches to determining the unknown thermophysical and radiation-optical characteristics. Laser hyperthermia of superficial tissues is one such case. The paper proposes a method for identifying a model of one-dimensional unsteady heating of a semitransparent sample using non-contact thermometry. A feature of the physical process under consideration is the possibility of its discretization. Due to this, a two-stage iterative procedure for solving the inverse heat transfer problem was formulated. The implementation of the proposed algorithm using software made it possible to carry out a computational experiment. The results showed the effectiveness of this approach. The presented method can be used in the development of means for monitoring and regulating the laser hyperthermia procedure.

A novel approach to generate non-isotropic surfaces for numerical quantification of thermal contact conductance

The quantification of heat flow between machine tool components is of major importance for a precise thermal prediction of the entire system. A common coupling condition between individual components is the contact heat transfer coefficient connecting the temperature field with the corresponding heat transfer at the investigated interface. However, the majority of numerical and analytical approaches assume isotropic contact surface profiles and neglect distinct surface structures caused by the manufacturing process. This assumption causes inaccuracies in the modeling as isotropic surfaces lead to an overprediction in heat transfer. Hence, this paper presents a novel approach to generate surface structures for numerical calculations considering the used machining parameters. Predicted contact heat transfer coefficients of the old as well as the new generation approach are presented and compared to experimental results offering the basis for future comprehensive investigations considering multiple parameters and materials.

Modeling of weak shock waves propagation in aqueous foam layer

Dynamics of low-intensity air shock waves in the shock tube containing an aqueous foam layer is theoretically investigated. Modeling of studied process is carried out using two-phase model of aqueous foam developed by the authors in single-pressure, single-speed and two-temperature approximations. The model takes into account the Ranz-Marshall interphase contact heat transfer, effective Herschel-Bulkley viscosity, which describes foam behavior as a non-Newtonian fluid, and elastic properties of aqueous foam under a weak shock impaction without destruction of foam structure. Properties of air and water as the foam components are described by realistic equations of state. Computer implementation of the aqueous foam model is carried out in the solver, developed by the authors in OpenFOAM software. The influence of aqueous foam viscoelastic properties on the intensity and structure of a shock wave has been investigated. When analyzing the obtained solutions, reliability of the proposed model and method of numerical modeling is estimated by comparative analysis of the found solutions and literature experimental data.

Numerical study of combustion and heat transfer in a composite heat carrier generator

To investigate the operational problems of the composite heat carrier generator (CHCG) in actual industrial applications such as overheating and poor safety performance, an integrated analytical model was established. For this model, the commercial software Fluent was first applied to simulate the gas-liquid turbulent flow, diesel vaporization and combustion, and the mixing process between the flue gas and the preheated water. Taking the parameters obtained from the Fluent model as the boundary condition, an indirect contact heat transfer model considering the heat transfer between the hot flue gas and the cold water has been solved. Based on this model, the areas where the phenomena of overheating and high thermal stress are prone to occur have been determined, and the size of the water sleeve has been redesigned.

Development of a novel brief quantitative sensory testing protocol that integrates static and dynamic pain assessments: Test-retest performance in healthy adults

Objective Quantitative sensory testing is an expanding pain research domain with numerous clinical and research applications. There is a recognized need for brief reliable quantitative sensory testing protocols that enhance assessment feasibility. This study aimed to integrate static (pain threshold, tolerance, suprathreshold) and dynamic (conditioned pain modulation, offset analgesia, temporal summation) pain reactivity measures into a brief 20-minute protocol that uses a single portable device. The test-retest performance of this optimized protocol was evaluated. Design Using a test-retest design, the brief quantitative sensory testing assessment was administered to participants on two occasions separated by exactly 7 days. Setting A clinical psychology research laboratory at Syracuse University. Subjects Participants were 33 healthy adults recruited from Syracuse University’s online research participation pool. Methods A portable computerized quantitative sensory testing device delivered contact-heat pain to assess static and dynamic pain measures in participants. Dynamic responses were continuously recorded using a computerized visual analog scale. Results Pain threshold, tolerance, and suprathreshold exhibited excellent reliability (intraclass correlations ranged from 0.80 to 0.83). Conditioned pain modulation, offset analgesia, temporal summation yielded reliability in the good to excellent range (intraclass correlations ranged from 0.66 to 0.71). Conclusions Findings suggested that this brief integrated QST protocol may reliably monitor human pain reactivity over brief periods. This protocol may enhance quantitative sensory testing feasibility in clinical and research settings.