Clarifying Optimum Setting Temperatures and Airflow Positions for Personal Air Conditioning System on Flight

In recent years, the demand for air travel has increased and many people have traveled by plane. Most passengers, however, feel stressed due to the limited cabin space. In order to make these passengers more comfortable, a personal air-conditioning system for the entire chair is needed. This is because the human body experiences discomfort from localized heating or cooling, and thus, it is necessary to provide appropriate airflow to each part of the body. In this paper, a personal air-conditioning system, which consists of six vertically installed air-conditioning vents, will be proposed. To clarify the setting temperature of each vent, the airflow around the passenger and the operative temperature of each part of the body is investigated using fluid simulation. In the simulation, the ideal temperature for each part of the body is defined and compared with the operative temperature to verify how close both temperatures are, resulting in determining the ideal setting temperature. The simulation result shows, that most parts of the body reach their ideal temperatures. In addition, the optimum setting temperature and position of each air-conditioning vent, which contribute to maintaining the thermal comfort of the human body on the plane, is clarified.

Magnetic Pulse Hybrid Joining of Polymer Composites to Metals

To lighten their vehicles, car manufacturers are inclined to substitute steel structures with aluminum alloys or composites parts. They are then faced with the constraints inherent to dissimilar (galvanized steel/aluminum) or hybrid (metal/composite) assemblies. Recent developments in magnetic pulse welding seems to offer a viable route. Very fast, this process can be robotized and generates a very localized heating system which limits the formation of intermetallic and damage the composite. Low energy consumption, without filler metal or smoke it is recognized as an environmentally friendly process. In this paper, electromagnetic pulse welding is exploited to assemble polymer composite to metals. Two techniques, a metallic insert in polymer composite or an external patch, have been tested with possible design considerations.

Effect of Tool Pin Geometry on the Microhardness and Surface Roughness of Friction Stir Processed Recycled AA 6063

Friction stir processing was experimented on recycled aluminum alloy 6063 to investigate the effects of varying friction stir tool pin geometry and friction stir processing parameters on the microhardness and surface roughness. Different tool pin geometry has great influence on the outcome as it alters the ability to provide localized heating and better material flow. This study was performed using two different types of tool pin geometry, namely, the cylindrical threaded and the taper threaded pins, across varying rotational speeds and feed rates. The mechanical properties of the processed workpiece were inspected and analyzed in terms of microhardness, microstructure, and surface roughness. The results show that the taper threaded tool offers the highest improvement in microhardness up to 63% at the lowest rotational speed and highest feed rate at 1150 rpm and 30 mm/min, respectively, and this is supported by microscopy images showing finer grains with the compact and homogenous distribution. The taper threaded tool also provided a better surface roughness than the cylindrical threaded tool. However, the surface produced by cylindrical threaded at 30 mm/min feed rates is as smooth and consistent as that of taper threaded tool.

Experimental Demonstration of a Stacked Hybrid Optoacoustic-Piezoelectric Transducer for Localized Heating and Enhanced Cavitation

Laser-generated focused ultrasound (LGFU) is an emerging modality for cavitation-based therapy. However, focal pressure amplitudes by LGFU alone to achieve pulsed cavitation are often lacking as a treatment depth increases. This requires a higher pressure from a transmitter surface and more laser energies that even approach to a damage threshold of transmitter. To mitigate the requirement for LGFU-induced cavitation, we propose LGFU configurations with a locally heated focal zone using an additional high-intensity focused ultrasound (HIFU) transmitter. After confirming heat-induced cavitation enhancement using two separate transmitters, we then developed a stacked hybrid optoacoustic-piezoelectric transmitter, which is a unique configuration made by coating an optoacoustic layer directly onto a piezoelectric substrate. This shared curvature design has great practical advantage without requiring the complex alignment of two focal zones. Moreover, this enabled the amplification of cavitation bubble density by 18.5-fold compared to the LGFU operation alone. Finally, the feasibility of tissue fragmentation was confirmed through a tissue-mimicking gel, using the combination of LGFU and HIFU (not via a stacked structure). We expect that the stacked transmitter can be effectively used for stronger and faster tissue fragmentation than the LGFU transmitter alone.

Greenhouse localized heating powered by a polygeneration system

Energy consumption in greenhouse heating could reach up to 90% of the total energy requirement depending on the type of greenhouse, environmental control equipment and location of the greenhouse. The use of climate conditioning technologies that exploit renewable energy and the application of passive systems to improve the energy efficiency and the sustainability of the greenhouse sector are recommended. During winter 2020-2021, an experimental test was carried out at the University of Bari in a Mediterranean greenhouse heated by a polygeneration system, composed of a solar system and an air-water heat pump. Three localized heating systems were tested to transfer thermal energy close to plants of Roman lettuce. Heating pipes were placed inside the cultivation substrate in the underground pipe system and on the cultivation substrate in the laid pipe system. The third system consists of metal plates heated by steel tubes and placed in the aerial area of plants. A weather climatic station and a sensor system interfaced with a data logger for continuous data acquisition and storage were used. The plate system was the best for air temperature rising, as it allowed an increase of 3.6% compared to the set-up without any localised heating system. The underground pipe system was the best for the soil heating, as it achieved a temperature increase of 92%. Localized soil heating systems contributed significantly to an earlier harvest by almost 2 weeks.

Role of localized heating on the workability of powder metallurgical Al–4% Ti components in cold compression

In the present work, localised heating has been adopted at the damage site of the cold upset materials and the role of this mechanism on the workability has been analysed. Cylindrical specimens containing 96% aluminium and 4% titanium were prepared through powder metallurgy technique with an aspect ratio (height to diameter) of 1 by suitable pressures. A series of cold upsetting test was conducted and the material properties for various preforms initial relative densities (80%, 85% and 90%) were determined under the stable strain rate. The flow of metals was analysed using a finite element tool and it was observed that the metal flow starts from near the centre zone to the equatorial zone and the damage happens in the outer position because of more amount of accumulated stresses and the pores. These stresses and pores decrease the workability of the final component. Hence, the present research is intended to reduce the stresses and minimize the pores by applying a localized heating (100 °C–250 °C) at the equatorial sites of the components and thereby increasing the workability of the material. Also, heating selectively at the equatorial site of the workpiece improves the workability due to change in grain size and it was noticed that the grain size of the developed porous preforms was high for the higher heating conditions due to the growth of the grains. Therefore, the localized heating adopted in this work is a superior method to enhance the workability of the powder samples and this novel technique could be useful in improving the workability of the structural components that have extensive applications in the automobile and aerospace industries.

Effect of Local Heat Application During Exercise on Gene Expression Related to Mitochondrial Homeostasis.

Determine the impact of local muscle heating during endurance exercise on human skeletal muscle mitochondrial-related gene expression. Twelve subjects (25±6 yrs, 177±8 cm, 78±16 kg, and VO2peak peak 45±8 ml·kg-1·min-1) cycled with one leg heated (HOT) and the other serving as a control (CON). Skin and intramuscular temperatures were taken before temperature intervention (Pre), after 30 min (Pre30), after exercise (Post) and four hours after exercise (4Post). Muscle biopsies were taken from each leg at Pre and 4Post. Intramuscular temperature increased within HOT (34.4±0.7ºC to 36.1±0.5ºC, p<0.001) and was higher than CON at Pre30 (34.0±0.7ºC, p<0.001). However, temperatures at POST were similar (HOT 38.4±0.7ºC, CON 38.3±0.5ºC, p=0.661). Skin temperature was higher than CON at Post30 (30.3±1.0ºC, p<0.001) and Post (HOT 34.6±0.9ºC, CON 32.3±1.6ºC, p<0.001). PGC-1α, VEGF and NRF2 mRNA increased with exercise (p<0.05) but was not altered with heating (p>0.05). TFAM increased after exercise with heat application (HOT, p=0.019) but not with exercise alone (CON, p=0.422). There was no difference in NRF1, ESRRα, or any of the mitophagy related genes in response to exercise or temperature (p>0.05). In conclusion, TFAM is enhanced by local heat application during endurance exercise, whereas other genes related to mitochondrial homeostasis are unaffected. Novelty: The main finding of this study is that localized heating increased TFAM mRNA expression. The normal exercise-induced increased PGC-1α gene expression was unaltered by local muscle heating.

Filtration of Nanoparticle Agglomerates in Aqueous Colloidal Suspensions Exposed to an External Radio-Frequency Magnetic Field

The study investigated the phenomenon of the fast aggregation of single-domain magnetic iron oxide nanoparticles in stable aqueous colloidal suspensions due to the presence of a radio-frequency (RF) magnetic field. Single-domain nanoparticles have specific magnetic properties, especially the unique property of absorbing the energy of such a field and releasing it in the form of heat. The localized heating causes the colloid to become unstable, leading to faster agglomeration of nanoparticles and, consequently, to rapid sedimentation. It has been shown that the destabilization of a stable magnetic nanoparticle colloid by the RF magnetic field can be used for the controlled filtration of larger agglomerates of the colloid solution. Two particular cases of stable colloidal suspensions were considered: a suspension of the bare nanoparticles in an alkaline solution and the silica-stabilized nanoparticles in a neutral solution. The obtained results are important primarily for biomedical applications and wastewater treatment.