Search Results (60)

This study explores the flame retardancy and structural behavior of silicone foam composites filled with halogen-free flame retardants, aiming to evaluate their feasibility for use in mass transportation applications. Silicone foam specimens incorporating magnesium hydroxide and expandable graphite were prepared and compared with unfilled silicone foam under both static and dynamic loading conditions. Uniaxial compression and simple shear tests were conducted to assess mechanical behavior, and a second-order Ogden model was employed to represent hyperelasticity in the finite element analysis. Fire performance was evaluated using cone calorimeter tests in accordance with ISO 5660-1. The results showed a 53.6% reduction in peak heat release rate (PHRR) and a 48.1% decrease in MARHE upon the addition of flame retardants, satisfying relevant fire safety standards. Although the addition of fillers increased the compressive stiffness and reduced rebound resilience, static comfort indices remained within acceptable ranges. These findings confirm that halogen-free filled silicone foams exhibit significantly enhanced fire retardancy while maintaining sufficient mechanical integrity and seating comfort, demonstrating their potential as eco-friendly alternatives to conventional polyurethane foams in large-scale transportation applications. Full article

Graphene films are widely used in thermal management of electronic devices due to their excellent properties such as high flexibility, high thermal conductivity and light weight. However, in the traditional preparation process, some structural defects are introduced, which will lead to an increase in phonon scattering, thereby reducing the thermal conductivity of graphene. Therefore, a new method for preparing graphene thin films is proposed by using the evaporation method; the graphene oxide composite film is prepared by adding carbon-rich molecules (CRMs) to the graphene oxide dispersion liquid. The experimental results show that the addition of a mass fraction of 0.15% CRMs helps to form continuous strips and channels, which are beneficial to the construction of the internal aromatic structure of graphene and improve the crystallinity of graphene film. The in-plane thermal conductivity of the composite film increased from 598.74 W/(m·K) to 704.27 W/(m·K) after adding carbon-rich molecules. However, excess CRMs can lead to the formation of disordered structures during graphitization, which will reduce the thermal conductivity of the film to a certain extent. The radiation properties of graphene films are also proposed to verify the validity of the above conclusions, and the results show that the graphene film with a mass fraction of 0.24% CRMs has better heat dissipation performance, which can be reduced by 5 °C compared with that of pure graphene film. Through the application of graphene in new energy car seats, it is proved that compared with the resistance wire seats, graphene seats have better performance in terms of a fast heating speed and uniform heating. Full article

The urban microclimate of Avenida dos Aliados and Praça da Liberdade was subjected to comprehensive examination through twelve measurement campaigns at six strategic observation points over the course of two seasons, namely summer and winter, between 2019 and 2020. The study employed an objective approach based on measurements to evaluate key microclimatic factors, including air temperature, which ranged from 15 °C in winter to a peak of 38 °C in summer, and Relative Humidity (RH), which varied from 50% to 85%. Additionally, wind speed was recorded between 1.0 m/s and 2.5 m/s, along with solar radiation levels, which significantly impacted Surface Temperatures (T_surf), reaching up to 38.0 °C in some areas. A parallel subjective survey questionnaire was conducted with 123 participants. In particular, the preference for shaded areas was highlighted through a thermal sensation map, with some places in Praça da Liberdade being a favored spot during summer due to its vegetation and lower T_surf. The study identified solar exposure, wind patterns, and T_surf as the key determinants of thermal comfort. It is noteworthy that shaded areas, particularly those with a substantial amount of greenery, were found to alleviate discomfort from the heat, thereby making them the preferred choice for pedestrians. Furthermore, the study underscored the significance of incorporating adaptive elements, such as greenery, shading structures, and ventilation corridors, into urban design to enhance comfort across different seasons. Results contribute with valuable insights for urban planners. The data indicate that urban design should prioritize the inclusion of pedestrian-friendly elements, such as shaded walkways and seating areas, to promote the active use of public spaces. This approach is particularly relevant in the context of climate change, where seasonal variations and increasing temperatures may exacerbate discomfort in urban environments. Full article

This study shows how the fire regulations for railway seats used in international traffic have changed over the last 30 years. In the past, a paper cushion was used as a flame source, and today, a 15 kW burner is used; consequently, the requirements have increased. In the paper cushion test, a foam with a density of between 60 and 95 kg/m³, a flame-retardant fleece, and a cover fabric was usually sufficient in terms of fire safety. Today, a high-quality flame-retardant foam is necessary to meet the requirements for flaming with the 15 kW burner. Two comparable seat structures show very different heat release and smoke formation in the paper cushion test due to different foam additives. If high-quality flame-retardant foams with a cover fabric are used for the 15 kW flame treatment, the results of the two test institutes show good agreement. If the seats that meet the requirements of the paper cushion test are flamed using the 15 kW treatment, they can catch fire and thus exhibit very different heat release rates, as the CERTIFER interlaboratory test with 12 participating test institutes shows. The heat release of old and new leather was examined, and it was found that the flame retardant applied to the leather surface appeared to have aged over the years and that the flame retardant was therefore no longer effective. The heat release of flame-retardant foams with a cover fabric was measured using irradiation with a cone calorimeter and flame treatment. Very different curves were observed, which means that it is not possible to draw simple conclusions about the heat release during flame treatment from the cone measurement. Full article

In exploring adjuvant therapies for head and neck cancer, hyperthermia (40–45 °C) has shown efficacy in enhancing chemotherapy and radiation, as well as the delivery of liposomal drugs. Current hyperthermia treatments, however, struggle to reach large deep tumors uniformly and non-invasively. This study investigates the feasibility of delivering targeted uniform hyperthermia deep into the tissue using a non-invasive ultrasound spherical random phased array transducer. Simulations in 3D patient-specific models for thyroid and oropharyngeal cancers assessed the transducer’s proficiency. The transducer consisting of 256 elements randomly positioned on a spherical shell, operated at a frequency of 1 MHz with various phasing schemes and power modulations to analyze 40, 41, and 43 °C isothermal volumes and the penetration depth of the heating volume, along with temperature uniformity within the target area using T10, T50, and T90 temperatures, across different tumor models. Intensity distributions and volumetric temperature contours were calculated to define moderate hyperthermia boundaries. The results indicated the array’s ability to produce controlled heating volumes from 1 to 48 cm³ at 40 °C, 0.35 to 27 cm³ at 41 °C, and 0.1 to 8 cm³ at 43 °C. The heating depths ranged from 7 to 39 mm minimum and 52 to 59 mm maximum, measured from the skin’s inner surface. The transducer, with optimal phasing and water-cooled bolus, confined the heating to the targeted regions effectively. Multifocal sonications also improved the heating homogeneity, reducing the length-to-diameter ratio by 38% when using eight foci versus a single one. This approach shows potential for treating a range of tumors, notably deep-seated and challenging oropharyngeal cancers. Full article

Lower back pain (LBP) is one of the most prevalent health losses in adults worldwide. Historically, heat has been successfully used for treating pain and relieving tight muscles. Given the effective contact with the occupant’s back and proximity to the heat source, coupled with increasing commute times, automotive seats offer an opportunity to intervene. Fifteen adults (nine female) who experienced acute, subacute, and chronic lower back pain were recruited to examine the effectiveness of heat delivered to the lower back in providing temporary pain relief. Participants sat in a car seat for 38 min on two days, which included a 5-min baseline followed by a 33-min intervention; control, or localized. For the control condition, participants sat for 33 min without any thermal devices on, while the localized condition heated and maintained the seat surface temperature of the lower seat back area to ~45 °C. Over the 33-min control condition, the back skin temperature increased by ~1–2 °C and did not impact the subjective LBP. Heating the lower back for 33 min to ~39 °C reduced the subjective LBP by 10%. We demonstrated that lower back pain can be alleviated from an automotive seat providing heat to the lower back within normal commute times in those with lower back pain. Full article

This study examines heat exposure and its impact on the thermal comfort and health of spectators within a semi-outdoor American college football stadium in the southeastern United States. Over 50 sensors were deployed during the 2016 season from late August to late November to measure temperature and humidity across various stadium locations. Significant variations in temperature, heat index, and a modified version of the physiological equivalent temperature (mPET) were found within the stadium, with some areas exceeding National Weather Service heat alert thresholds during certain games. Moreover, mean temperatures in the stadium were higher than those measured at a nearby weather station, while the mean heat index was higher in the seating areas than in other stadium locations and at the nearby weather station. Reductions in modeled wind speed resulted in significant decreases in thermal comfort and greater physical stress among spectators, particularly when the wind was calm. Heat-related illness comprised up to two-thirds of all cases treated by first aid and emergency medical services during particularly hot games. Most of these occurred in the most thermally oppressive parts of the stadium. These results highlight the need for greater monitoring of heat exposure inside stadiums, earlier implementation of heat action plans to raise awareness and educate spectators on heat mitigation strategies, and incorporation of stadium design modifications that improve circulation, increase shade, and reduce crowding. Full article

In this paper, by comparing the archaeological remains of meditation caves in Kucha and Termez and by referring to Buddhist literature, we aim at gaining a better understanding of how meditation was practiced in both regions. In Kucha and Termez the arid climate shifted between extreme summer heat and extreme winter cold, making the caves ideal choices for meditation. In Kucha, various types of meditation caves have been recorded. These include small cells for seated meditation, single corridors, and corridors that intersect to form a cross or an inverted U plan. The latter type is associated with a residence and a courtyard, which show many similarities with the complexes located in the mounds south and west of the monastery of Kara Tepe. Two possible uses of the corridor-shaped caves have been proposed based on various factors, such as the distance of the caves from the surface monastery, the similarity of the type, the presence of a courtyard in front of the caves, and the existence of a cell where a person could repose. Buddhist accounts remark on the importance of mindful pacing (Skt. caṅkrama; Chi. jingxing 經行) along with sitting meditation in the daily practice of bhikṣus. According to descriptions in the vinaya, we can infer the possibility of having several types of pathways for mindful pacing, besides the most common straight path. Note also that various ancient records of Buddhist monks mention monuments associated with mindful pacing. Drawing on both architectural remains of the investigated areas and textual evidence, we suggest that the carved corridors, both single and intersecting, might have been specifically designed for mindful pacing. In the better-preserved complexes, the length of the courtyard’s sides corresponds with that of the corridors. While the courtyard could have been utilized for various activities, the similarity in size between corridors and the courtyard hints at its potential use for mindful pacing in mild weather. Furthermore, because the Kara Tepe monastery could accommodate less than fifteen monks, the presence of several meditation complexes, each consisting of four intersecting corridors and a small cell, implies that these units were intended for a monk to live in seclusion for a period. Full article

This study investigates the applicability of eco-friendly silicone materials with improved flame retardancy as interior materials for Korean urban railway vehicles, focusing on developing nonslip pads for seats made of non-combustible materials. Fire safety standards vary worldwide, necessitating country-specific testing and analysis. For application to the interior of railway vehicles in Korea, technical standards for the flame-retardant performance of railway vehicles were evaluated, and nonslip pads for seats were tested by comparing two types of flame-retardant silicone. In addition to fire property testing on a specimen basis, experimental verification was performed on a full chair assembly including silicone pads. Passenger comfort testing through pressure measurements was also conducted alongside fire safety performance testing The actual fire test showed that the maximum average heat release rate value was about 20% lower than the standard’s upper limit. Using flame-retardant silicone pads enhances fire safety and passenger comfort, satisfactorily meeting the required performance standards for Korean railway vehicles. Full article

The terrestrial heat flow and lithospheric thermal structure of sedimentary basins are crucial for understanding basin dynamics and assessing geothermal resources. This study computed the heat flow in the Hubao Basin using rock thermal conductivity and borehole temperature data. Combined with the geophysical profile of the Yinshan Orogenic Belt–Hubao Basin–Ordos Basin, the lithospheric thermal structure was studied, and the geodynamic mechanism is discussed. The results indicate that the heat flow in the Hubao Basin ranges from 64.0 to 73.8 mW/m². The Moho temperature along the profile varies between 570 and 652 °C, and the thickness of the thermal lithosphere ranges from 122.7 to 138.8 km. Using the backstripping method to calculate the crust–mantle heat flow ratio, we find that this ratio in in the Hubao Basin is approximately 1, indicating a “warm crust, warm mantle” type of lithospheric thermal structure. This is related to the combined effects of extensional tectonics since the Late Jurassic and Early Cretaceous, westward subduction of the Pacific Plate, remote effects from the Indian Ocean Plate, and the development of deep-seated faults within the basin. The combined effects of lithospheric thinning and deep-seated faults have resulted in thermal anomalies in the Hubao Basin. Full article

Car-sharing services, which provide short-term vehicle rentals in urban centers, are rapidly expanding globally but also face numerous challenges. A significant challenge is the effective management of fleet selection to meet user expectations. Addressing this challenge, as well as methodological and literature gaps, the objective of this article is to present an original methodology that supports the evaluation of the suitability of vehicle fleets used in car-sharing systems and to identify the vehicle features preferred by users necessary for specific types of travel. The proposed methodology, which incorporates elements of transportation system modeling and concurrent analysis, was tested using a real-world case study involving a car-sharing service operator. The research focused on the commuting needs of car-sharing users for work or educational purposes. The study was conducted for a German car-sharing operator in Berlin. The research was carried out from 1 January to 30 June 2022. The findings indicate that the best vehicles for the respondents are large cars representing classes D or E, equipped with a combustion engine with a power of 63 to 149 kW, at least parking sensors, navigation, hands-free, lane assistant, heated seats, and high safety standards as indicated by Euro NCAP ratings, offered at the lowest possible rental price. The results align with market trends in Germany, which focus on the sale of at least medium-sized vehicles. This suggests a limitation of small cars in car-sharing systems, which were ideologically supposed to be a key fleet in those kinds of services. The developed methodology supports both system operators in verifying whether their fleet meets user needs and urban policymakers in effectively managing policies towards car-sharing services, including fleet composition, pricing regulations, and vehicle equipment standards. This work represents a significant step towards enhancing the efficiency of car-sharing services in the context of smart cities, where personalization and optimizing transport are crucial for sustainable development. Full article

The combined heating method of seat heating and air conditioning (A/C) was applied in the passenger compartment under different experiment conditions, using thermocouples to continuously measure the wall surfaces and air temperatures in the passenger compartment and the passengers’ skin temperatures of 17 segments. Meanwhile, a subjective evaluation questionnaire survey was conducted using a nine-point evaluation scale on the local and overall thermal sensation and thermal comfort of the passengers, and the data from the questionnaire were analyzed with the ANOVA method. The results showed that the use of the heating pad directly affected the changes in human skin temperature, which in turn affected the local and overall thermal sensation and thermal comfort. For the two thermally stimulated segments of the back and under the thighs, the skin temperature of the back was higher than that of the thighs. Using the heating pad resulted in a rapid increase in the mean skin temperature in the early period of the experiment. Thermal sensation of the back and under-thighs shifted rapidly towards the hot zone in the first 10 min, and then settled around +3, with even more significant differences between the groups. Thermal sensations in non-thermally stimulated segments changed in relation to their position on the heating pad, with slower changes in those at the “distal” end of the body, the head and the feet. Continued use of the heating pads at lower ambient temperatures maintained overall thermal comfort at a neutral level in the range of 0–1, whereas at higher ambient temperatures there was a gradual deterioration of local and overall thermal comfort. Full article

This paper investigates the microclimate in a conference room with thermal stratification, taking as a case study the chapel of Villa San Saverio, now the seat of the “Scuola Superiore” of the University of Catania (Italy). Surveys of the former chapel were conducted to monitor air temperature and relative humidity. Subsequently, the investigation relied on numerical simulations of a simplified computational fluid dynamics (CFD) model built with the DesignBuilder v7.0 software and validated by comparison with measured values. Simulations were then carried out considering three different scenarios: the current state without any HVAC system and two possible HVAC system configurations providing both air conditioning and ventilation. The results show that, from a comfort perspective, a lightweight radiant floor heating system, assisted by an appropriate ventilation system for air renewal placed at the floor level near the occupants, is preferable to floor-level fan coils and high ventilation channels. Furthermore, this was also confirmed by a preliminary energy analysis of the two HVAC options, where the ventilation effectiveness of the winter period, the temperature of the water the emitters are fed, the consequent COP value of the heat pump, and the electricity consumption were taken into consideration. Full article

Railway wheels are usually attached to axles by press-fitting; therefore, the mechanical processes taking place during operation can result in failure, with fatal consequences for the axle seats. This manuscript describes the effect of laser hardening on the residual stress state, microstructural parameters (lattice defects—dislocations, crystallites, microstrains, etc.), and mechanical properties of laser-hardened EA1N steel railway axles under fatigue life conditions. Differences were found between ground, single-track, and multi-track hardened surfaces. Tensile residual stresses, low dislocation densities and hardnesses, and different microstructures (tempered cubic martensite) were found at the overlapped tracks and at the boundary of the heat-affected zone and bulk surface compared with the hardened zone. As a result, the surface treatment of axle seats by laser hardening improved the fatigue failure resistance compared with untreated seats. Optimal properties of the integrity of the axle seat surface were achieved, including fatigue resistance, which seems to be positively influenced mainly by sufficient hardness and the appropriate microstructure. The influence of the other investigated parameters was not evident, and was reduced by the presence of fretting corrosion and press-fitting. Full article

Water-based chloroprene latex is a solvent-free, environmentally friendly adhesive. Currently, its market demand is growing rapidly. However, there are problems such as a lack of heat resistance and poor mechanical properties, which limit its application. The introduction of vinyl-POSS (OVS) into the resin structure can effectively improve the thermal stability of chloroprene adhesives. In this paper, modified waterborne chloroprene latex was prepared by copolymerization of methyl methacrylate and OVS with chloroprene latex. The results showed that vinyl-POSS was successfully grafted onto the main chain of the waterborne chloroprene latex, and the modified waterborne chloroprene latex had good storage stability. With the increase in vinyl-POSS, the tensile strength of the chloroprene latex firstly increased and then decreased, the tensile property (peel strength of 20.2 kgf) was maintained well at a high temperature (100 °C), and the thermal stability of the chloroprene latex was improved. When the addition amount was 4%, the comprehensive mechanical properties were their best. This study provides a new idea for the construction of a new and efficient waterborne chloroprene latex system and provides more fields for the practical application of waterborne chloroprene latex. This newly developed vinyl-POSS modified chloroprene latex has great application potential for use in home furniture, bags, and seat cushions. Full article