1,720,975 research outputs found
The use of wool as fiber-reinforcement in cement-based mortar
No full textAs the mechanical response is better than in plain cement-based mortars, fiber-reinforced mortars are widely used in the construction industry. Specifically, the fracture toughness in tension increases with the volume and the aspect ratio (i.e., the ratio between length and diameter) of the fibers, which are generally made with polymeric (e.g., polyethylene, polyvinylchloride, etc.) or inorganic (e.g., glass, carbon, etc.) materials, or with steel. However, some vegetal fibers, such as bamboo and hemp, have been also introduced in the last decades. To produce new mortars with animal fibers, the use of wool as fiber-reinforcement is investigated for the first time in the present paper. According to UNI EN 196-1-2006, three point bending tests have been performed on three series of beams: plain mortar, mortar reinforced with 1% in volume of wool, and mortar reinforced with 1% in volume of treated wool. In the latter case, wool is previously treated with atmospheric plasma in order to modify the nano-metric properties of the fiber surface. As a result, both the flexural strength and the ductility increase when wool, plain or treated, is added to cementitious mortars. In other words, wool does improve the mechanical and ecological performances of cementitious mortars and creates a link between textile and construction market
Ergonomic Comfort of Trekking Backpacks: Measurements of Pressure Exerted by Shoulder Straps and Hip Belt in Female Users
No full textThe pressure exerted by trekking backpacks (BPs) of different volumes and construction designs was measured in six female users using a pneumatic sensor. The aim was to investigate the effects of gender-specific design on ergonomic comfort. Although no difference was found in terms of pressure in the female BP models, a correlation was found between pressure and biometric characteristics (BMI, chest and waist circumference). The results suggest that the ergonomic comfort of BP depends on the size of the user, with slim users more likely to experience uncomfortably high pressure from shoulder straps and hip belt
Metodo di valutazione del comfort termico e progettazione di capi innovativi
No full textDocumentazione del convegno conclusivo del progetto Hite
Thermo-physiological comfort of soft-shell back protectors under controlled environmental conditions
No full textThe aim of the study was to investigate thermo-physiological comfort of three back protectors identifying design features affecting heat loss and moisture management. Five volunteers tested the back protectors in a climatic chamber during an intermittent physical activity. Heart rate, average skin temperature, sweat production, microclimate temperature and humidity have been monitored during the test. The sources of heat losses have been identified using infrared thermography and the participants answered a questionnaire to express their subjective sensations associated with their thermo-physiological condition. The results have shown that locally torso skin temperature and microclimate depended on the type of back protector, whose design allowed different extent of perspiration and thermal insulation. Coupling physiological measurements with the questionnaire, it was found that overall comfort was dependent more on skin wetness than skin temperature: the participants preferred the back protector with the highest level of ventilation through the shell and the lowest level of microclimate humidity
Thermoregulation of feet in cold environments: A study on alpinism
No full textThermal comfort plays a crucial role in the performance and well-being of mountaineers, especially in extreme
environments. The aim of this study was to develop a reliable protocol to assess the thermal comfort of
mountaineering boots, with a specific focus on temperature variations in different regions of the foot and their
correlation with physiological factors. Two different models of mountaineering boots were tested at two different
environmental temperature (-15◦C and -30◦C). The mean skin temperature, measured according to International
Standards BS EN ISO 9886:2004, was used as an indicator of overall thermal comfort. Physiological factors such
as heart rate (HR), body mass index (BMI) and body surface area (BSA) were also measured to understand their
relationship to thermoregulation. Kruskal-Wallis and Pearson’s ProductMoment correlation tests were performed
to investigate whether there was a statistically significant relationship.
The results showed significant differences in foot temperature among the Testers, indicating variations in the
perception of thermal comfort. The correlation analysis showed a strong positive relationship between mean
skin temperature and HR, highlighting the influence of physiological factors on thermal comfort.
In addition, the analysis showed that the dorsum and hallux areas had the largest temperature variations,
suggesting the occurrence of vasoconstriction and potential discomfort.
This study represents a preliminary approach to establishing a reliable protocol for assessing the thermal
performance of cold protective footwea
Thermal comfort of soft-shell back protectors for alpine skiing
No full textIntroduction
In the last few years the soft-shell back protectors have widely replaced the previously used hard-shell protectors. The soft foamed materials used for soft-shell back protectors provide great impact absorption capability due to their pseudo-dilatant behaviour that permits to the protector to be soft under low speed impacts and to become hard for high speed impacts. Moreover, the soft foams provide a better fit over the body and allow manufactures to create perforated structures of the foam pad that can improve the temperature control and moisture management. The aim of this work has been to measure how back-protectors perform, in terms of heating, cooling, moisture management and therefore overall thermal comfort, under controlled environmental conditions. Three different commercial back protectors have been used in order to compare how materials and design can influence the above mentioned thermal properties.
Materials/Methods
Five testers have tested three types of soft shell back protectors in a climatic chamber in order to evaluate the thermal performances of each back protector. Temperature and humidity sensors, distributed in 11 different body positions, have allowed the measure of the skin mean and torso temperatures and the microclimate humidity and temperature in the zone between the skin and the back-protector. Moreover, the mechanism of heat dissipation has bee studied usingthermo-graphic imaging. The tests have been performed running on a treadmill under controlled physical activity. Both objective and subjective parameters have been analysed, in order to define an appropriate method for the comparison of back protectors with different materials and designs. The physical activity level has been evaluated using an heart rate monitor, while the sweat rate has been used as indication of the thermal stress of the tester.
Results and Conclusions.
The method developed in this work has allowed a detailed evaluation on how the different types of back protectors influence the thermo-physiological comfort of the final user. The results obtained show minor differences from a global point of view (Average Skin Temperature). However, looking more in detail into the thermal micro-climate locally in the torso area (Average Torso Temperature), the differences are larger still maintaining the same thermal performance hierarchy of the average skin temperature
Thermo-physiological comfort of a PES fabric with incorporated activated carbon - Part I: preliminary physical analysis
No full textPurposeThe purpose of this paper is to evaluate the thermo‐physiological comfort of a knitted polyester (PES) fabric which contains activated carbon particles in the back‐side.Design/methodology/approachAccording to the manufacturer's intention, the activated carbon particles, added in the PES extrusion process, give permanent attributes to the garment, such as odour resistance, UV protection and evaporative cooling. These features should make the modified PES ideal for sportswear. Standard fabric characteristics (morphology, mass per unit area, thickness) have been evaluated for two similar fabrics, the one containing the modified PES yarn and the other one made of conventional PES yarn. The investigated thermo‐physiological properties were air permeability (AP), water vapour resistance (Ret ), thermal resistance (Rct ), thermal conductivity and diffusion, drying rate, vertical wicking, horizontal liquid diffusion area and buffering capacity. They have been measured in controlled thermal and humidity conditions in a climatic chamber.FindingsThe modified fabric is more hydrophilic than the conventional one, thanks to the carbon particles sorption ability. Thus, the liquid management of the modified PES fabric was found to be better. On the other hand, liquid desorption was slow and the drying time was longer. Moreover, the dry heat and the vapour transfer were found slightly worse for the modified PES, probably due to the lower AP.Originality/valueThe paper shows a comprehensive fabric characterization of a functionalized fabric, highlighting the positive and negative effects of activated carbon particles on the liquid, vapour and heat management.</jats:sec
Impact of Backpacks on Ergonomics: Biomechanical and Physiological Effects: A Narrative Review
Full text link(1) Background: the effects of load carriage packs on human gait biomechanics, physiology and metabolism depend on the weight carried, the design of the pack and its interaction with the user. (2) Methods: An extensive search in the PubMed database was performed to find all the relevant articles using the following keywords: backpack, rucksack, backpack ergonomy and sports backpack; 60 articles were included. (3) Results and significance: Double pack (DP) and T-pack (TP) designs are recommended solutions for school children, compared with backpacks (BP). For soldiers and hikers, a backpack remains the best compromise. A hip belt is recommended for BPs as well as for the back of DPs. Shorter and stiffer shoulder straps combined with a higher and tighter load placement on the back provide the best combination in terms of balance, muscle activation and energy expenditure. It is, therefore, possible to determine guidelines for designing the optimal load carriage system, depending on the application. (4) Conclusions: based on the available evidence, DP and TP are advantageous in terms of posture. DP is better than conventional BPs in terms of balance and muscle activation, but has the disadvantage of limited visibility, thermal sensation and obstructed ventilation. In general, it is desirable not to exceed 40% of body mass (BM)
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