Thermal Micro Research Articles

EVALUATION OF THERMAL COMFORT IN TERMS OF OCCUPATIONAL SAFETY IN WEAVING FACILITIES BY FUZZY LOGIC

The fuzzy-based approach was chosen because fuzzy logic enables computerization of human reasoning. In recent years, Forecast accuracy and applicability to success in general. Models that show as fuzzy were developed. Data that are difficult to collect with exceptional predictive accuracy can be developed by utilizing the experience of fuzzy logic based models. One of the basic conditions necessary for a person to continue his life in a healthy way is to keep the body temperature at a normal temperature. Thermal comfort means that the majority of the workers in the working environment are in a certain comfort while continuing their physical and mental activities in terms of climatic conditions such as temperature, humidity and air flow rate. If the thermal comfort conditions are insufficient in the working environment, distress is felt and discomfort begins, and accordingly, the working capacity and work efficiency of the person decreases. In this article, temperature physiology and occupational health will be evaluated with fuzzy logic in weaving business. Recognition of risks in the work environment is the most important factor in preventing occupational disease, work-related illness and occupational accidents. The air flow velocity Va (m/s) read from the thermal micro air conditioner is a parameter related to how people in an environment perceive the environment in which the components of personal and environmental factors affecting thermal comfort are expressed mathematically, using PMV and PMV value. The index PPD change, which indicates the rate of change, was determined with the help of fuzzy logic.

Development of an Early Embryo Detection Methodology for Quail Eggs Using a Thermal Micro Camera and the YOLO Deep Learning Algorithm.

Poultry production utilizes many available technologies in terms of farm-industry automation and sanitary control. However, there is a lack of robust techniques and affordable equipment for avian embryo detection and sexual segregation at the early stages. In this work, we aimed to evaluate the potential use of thermal micro cameras for detecting embryos in quail eggs via thermal images during the first 168 h (7 days) of incubation. We propose a methodology to collect data during the incubation period. Additionally, to support the visual analysis, YOLO deep learning object detection algorithms were applied to detect unfertilized eggs; the results showed its potential to distinguish fertilized eggs from unfertilized eggs during the incubation period, after filtering radiometric images. We compared YOLOv4, YOLOv5 and SSD-MobileNet V2 trained models. The mAP@0.50 of the YOLOv4, YOLOv5 and SSD-MobileNet V2 was 98.62%, 99.5% and 91.8%, respectively. We also compared three testing datasets for different intervals of rotation of eggs, as our hypothesis was that fewer turning periods could improve the visualization of fertilized egg features, and applied three treatments: 1.5 h, 6 h, and 12 h. The results showed that turning eggs in different periods did not exhibit a linear relation, as the F1 Score for YOLOv4 of detection for the 12 h period was 0.569, that for the 6 h period was 0.404 and that for the 1.5 h period was 0.384. YOLOv5 F1 Scores for 12 h, 6 h and 1.5 h were 1, 0.545 and 0.386, respectively. SSD-MobileNet V2 performed F1 scores of 0.60 for 12 h, 0.22 for 6 h and 0 for 1.5 h turning periods.

Supercritical carbon dioxide in an array of micro impinging jets

Heat transfer of micro multi-jet with supercritical carbon dioxide is experimentally studied. A thermal micro specimen chip constituting of a concentric distribution of three resistance temperature detectors (RTDs) on a serpentine heater, which was mechanically supported by a 500 µm thick fused silica substrate, was microfabricated and used to obtain the heat transfer coefficient under a range of operating conditions. The jets issued from a concentric array of thirteen micro jets with an interject spacing (S/d) of ∼ 1.5, each measuring ∅205 µm, which were perpendicularly positioned over the temperature sensors with a relative standoff, L/d, of 7.3. The effect of radial position, heat flux, mass flux and inlet pressure on the heat transfer were studied at an inlet temperature of 21.7 °C.Results showed a uniform heat transfer coefficient over the heater with optimum values recorded mostly around the pseudocritical condition. In addition, the heat transfer coefficient increased with pressure above the critical condition, which was tied to a corresponding increase in the pseudocritical temperature. Furthermore, the observed heat transfer characteristics of the micro jet impingement cooling using multi-jet were compared to single jet under the same working conditions. This comparison showed that although the multi-jet ensued a more uniform temperature distribution over the heater, the single jet performed better due to an undermined heat transfer process in the multi-jet — a consequence of the jet-to-jet interaction.

Study on Fixed-Point Growth of Thermal Bubble with Micro-Planar Induction Heater

Background: The thermal bubble-driven micro actuators have advantages of simple structure and low working voltage, which have broad prospects in the field of micro-fluidic systems. Methods: This paper presents a new type of micro-planar induction heater which can realize the fixed-point growth of thermal bubbles by adding some active cavities. The micro-planar induction heater is composed of a metal heating plate, a glass substrate, and a planar coil. Results: In the experiments, an alternating current of 80 kHz was applied to the micro-planar induction heater; both the heating time and the interruption time were 1 s controlled by a PLC. A CCD camera was used to record the generation process of thermal bubbles, including nucleation, growth, and shrinkage. The experimental results show that thermal bubbles can grow and contract periodically at the position of the cavities when the cavities diameter is 50 μm and 90 μm, respectively. The ideal thickness of the heating plate is between 6 μm and 13 μm. Conclusion:: Here, the fixed-point growth of the thermal bubble with a micro-planar induction heater has been studied. This kind of fixed-point growth of thermal bubbles can be used in micro actuators, such as micro ejectors, micro mixers, and micro pumps.

Microablative Fractional Radiofrequency as a Therapeutical Option for Genitourinary Syndrome of Menopause: Perspectives.

The genitourinary syndrome in menopause can occur at different stages of life, with different causes or triggering factors, such as prolonged use of antiestrogens, chemotherapy, radiotherapy, and extensive vaginal surgeries, which can alter vascularization, hydration, collagen quality, and tissue elasticity. Despite hormonal therapy being considered the best evidenced treatment for genitourinary syndrome of menopause (GSM), there are limitations concerning the latter. Thus, alternative, complementary, or even substitutive treatments have emerged, such as energy use, promoting thermal tissue stimulation to improve tropism. Due to its practicality and feasibility, the micro ablative fractional radiofrequency (MAFRF) has gained space among these energies. It uses high-frequency electromagnetic waves and promotes thermal micro points in the superficial and deep dermis. The safety of these energies limits thermal action laterality and depth. Laterally, it is essential for an adequate regenerative effect without scarring marks or sequelae; the appropriate depth is important for stimulating the obligatory tissue repair response with the production and reorganization of collagen, elastic fibers, increased vascularization and hydration, and the consequent improvement in tropism. In gynecology, the MAFRF is used with therapeutic indication and functional improvement; it is applied to the entire length of the vaginal walls, the vulvar vestibule, urethral meatus, labia minora, clitoris prepuce, labia majora, perineum, and perianal region. The MAFRF has been proved to be an effective and safe treatment for GSM, with long-lasting effects, significantly reducing symptoms and improving vaginal tropism. This review aims to analyze the MAFRF as a non-hormonal therapeutic option for GSM.

Thermal Behavior and Characteristics of Functional Groups on Lignite Secondary Oxidation

ABSTRACT At present, the thermal behavior of lignite and the reaction process of functional groups during secondary oxidation have not been accurately explained. Therefore, the macro thermal behavior and micro characteristics of spontaneous combustion of lignite during secondary oxidation were studied. Coal samples were pre-oxidized to 80 °C, 120 °C, 160 °C, and 200 °C (labeled as raw coal, C-80, C-120, C-160, and C-200, respectively). A thermogravimetric (TG) analyzer and Fourier-Transform Infrared (FTIR) spectrometer were used. The results showed that the high adsorption temperature T1 and critical temperature T2 of C-80 were higher than those of raw coal by 4.41 °C and 11.07 °C, respectively. They indicated that pre-oxidation inhibited the low-temperature oxidation process. The active temperature T4 gradually decreased from C-80 to lower than that of raw coal. The T4 of C-200 was about 20 °C lower than that of raw coal, proving that pre-oxidation accelerated oxygen absorption and the weight-gaining process. The activation energy of pre-oxidized coal samples was significantly lower than that of raw coal samples. The C-80 and C-120 samples had the lowest activation energies: 114.542 kJ/mol and 114.539 kJ/mol, respectively. The content of free hydroxyl groups in pre-oxidized coal samples decreased in general. At C-120, the aliphatic hydrocarbon generation rate significantly increased, and the percentage of peak area continued to increase. During secondary oxidation of C-120 coal samples, various absorption peaks gradually enhanced. Consequently, C-120 was more prone to spontaneous combustion during secondary oxidation.

Integrated thermal dissipation micro structures for CDFP optical module

400 Gbit/s optical module will soon be commercially deployed on a large scale due to the need for high capacity information transmission. It has much higher power density than that of 100 Gbit/s and 40 Gbit/s and therefore the thermal management still remains an obstacle. Microscale and nanoscale thermal management technology emerges and blooms. Concentrating on the thermal design of CDFP optical module, we propose two integrated thermal dissipation micro structures (ITDMS). The first is graphene thermal pad (GTP)-based one, the second is Ω-typed (OMEGA). Based on basic heat transfer equations and by SOLIDWORKS Flow Simulation software, the ITDMS are numerically validated for effective heat dissipation of CDFP optical modules and hence have great prospects for solving the heat dissipation problem of high-speed broadband optical modules due to the thermal integration solutions.

Thermal Micro-Environment during Poultry Transportation in South Central United States.

Simple SummaryThis project monitored the internal micro-environments of live poultry transport trailers during loading and transport. For the 28 trips evaluated, trailers were modified using common USA industry mitigation practices designed to optimize bird comfort under a wide range of environmental conditions. In the cold season, double boarding of the exterior area of the transport modules elevated the internal temperature more than 8 °C above ambient temperatures as low as −16 °C. However, the temperature elevation may not be sufficient when ambient temperature was below 0 °C. In the warm season, surface wetting of birds and evaporative cooling applied during on-farm loading maintained trailer thermal conditions at or below ambient temperature for part of the road transport. However, this study suggests that additional improvement in equipment design or management is warranted when temperatures are extremely cold or hot.This observational study was conducted to characterize the thermal micro- climate that broilers experienced in commercial poultry transporters under various weather conditions and typical management practices in the South Central USA. We continuously monitored temperature and relative humidity in 45 interior locations of 28 fully-loaded commercial trailers over 2 year spans from 2015–2016 in South Central USA. In the cold season, double boarding of the exterior area of the transport modules maintained temperatures at least 8 °C warmer than ambient temperatures as low as −16 °C. Overall, temperature at all locations decreased as transporters traveled from farms to processing plants during winter trips with double boards. In the hot season, assistance by evaporative cooling during on-farm loading resulted in interior temperatures within ± 2 °C of ambient conditions (up to 36 °C) during road transport. In the summer months, trailers uniformly gained 2 °C as vehicles travelled for 45 min from farms to plants. Apparent equivalent temperatures of the monitored summer trips averaged 80.5 °C, indicating possible heat stress conditions based on the thermal comfort zones defined by literature index values. For longer trips, cooling assistance on the farms may be insufficient to prevent temperatures from rising further into extremely hot conditions in the transporters, leading to a dangerous thermal environment.

Global and local environmental and energy advantages of a geothermal heat pump interacting with a low temperature thermal micro grid

Urban heat island affects cities climate and results in higher air temperature with respect to the surrounding rural zones. Anthropogenic heat released by human activities exacerbates this phenomenon which impacts on environmental and energy fields. Air conditioning is commonly used to achieve comfort indoor conditions in the warmer urban climate but it is also one of the serious cause of the urban heat islands. The heat rejected by the condensers of air conditioning systems, increases the air temperature next to the buildings in which they are installed. In this paper a system consisting of a ground-source heat pump, a low temperature thermal network and a series of electric heat pumps, is analysed. The thermal grid is the heat source/sink for the water to water electric heat pumps that are installed at each end-user of a multi-purpose six floors building located in Naples (Southern of Italy). In cooling mode the condenser heat is discarded in the ground by the ground source heat pump that operates between the lower temperature thermal grid and the borefield. In the heating period the thermal network is heated by the ground source heat pump, that draws energy from the ground. The models simulating the energy conversion systems, the low temperature thermal network and the building, are implemented in the dynamic simulation software TRNSYS 17. A first advantage of the proposed configuration is the avoided interaction with the outside air and the corresponding mitigation of the urban heat island phenomenon. A second one is the higher coefficient of performance of the water to water electric heat pumps, operating with a lower temperature gap with respect to the case in which the electric heat pumps interact with the outside air. Furthermore, the interaction with thermal grid allows high seasonal performance due to the low fluctuation of the temperature with respect to the air. Finally this energy efficient system could be simply installed not only in the new buildings, but also in refurbishments. The proposed system is compared with a conventional one installed in each dwelling consisting of an air to water air conditioner for cooling operation and a boiler for heating. Interesting global and local environmental advantages are obtained.

Dynamic pull-in of thermal cantilever nanoswitches subjected to dispersion and axial forces using nonlocal elasticity theory

Precise analysis of nanoelectromechanical systems has an outstanding contribution in performance improvement of such systems. In this research, the dynamic instability of a cantilever nanobeam connected to a horizontal spring is analyzed. The system is subjected to thermal, electrostatic and molecular (Casimir and van der Waals) forces. By applying the Eringen’s nonlocal elasticity theory, the equilibrium equations are derived. The nonlinear dynamics governing equations of the actuated thermal switch are solved by reduced order method. Finally, the effects of several system parameters on the dynamic behavior of the nanocantilever are examined in detail. It is concluded that considering the nonlocal theory results in increasing the rigidity of cantilever nanobeams, unlike fixed-fixed nanobeams. Furthermore, the nonlocality affects more significantly by increasing the temperature of cantilevers; however, it is completely the opposite for double-clamped beams. The obtained results can be considered for modeling and analysis of several thermal micro and nanosystems.

Numerical modelling, simulation and fabrication of 3-D hemi-spherical convex micro features using Reverse Micro EDM

Reverse Micro Electrical Discharge Machining (RMEDM), a variant of Micro Electrical Discharge Machining (MEDM) is a non-contact thermal micro machining process extensively used for fabrication of high aspect ratio single or multiple 2.5-D features with different cross-sections like square, circular, triangular etc. The process capability is limited by difficulty in debris ejection through the small inter-electrode gap (few μm) which causes debris sticking to electrodes and thereby creating unwanted secondary and higher order erosion that affects the features generated. In this paper, an attempt has been made to numerically model, simulate and experimentally investigate the fabrication of 3-D convex hemi-spherical micro feature by taking advantage of the effect of secondary and higher order erosion of debris. Array of 3-D hemispherical shaped micro features finds application in the field of micro lens let arrays, solar cells etc. Results indicate that use of taper ended blind hole leads to debris accumulation towards the corners and edges of cathode which enhances the possibility of secondary and higher order erosion at those areas leading to generation of 3-D convex hemi-spherical micro feature on the anode. Also, the relation between material removal by secondary and higher order erosion to that of primary erosion during machining was derived. Different values of k0 (averaged for entire machining depth) were found affecting the shape of generated micro feature. In this study, material removal by secondary and higher order erosion was found to be five times that of primary erosion.

A study of the current density analysis for two type method on the invar alloy in electrochemical machining

Invar alloy is important material used for the OLED (Organic light emitting diode) shadow-mask in the mobile display industry due to its characteristics of smallest thermal expansion coefficient. Consumers in modern society demand higher display resolution. Electrochemical machining is one of the methods for obtained these high-resolution requirements. Electrochemical machining is a non-contact method that has advantages regarding defects like thermal strain and micro burrs compared to other non-conventional machining methods. For precision electrochemical machining using different shape electrodes, the current density should be controlled precisely. The purpose of this study is to apply the FEM (Finite elements method) analysis in order to investigate the current density in the electrochemical machining. And the current density distribution between invar alloy and electrode are carried out with shape electrode type and micro array film type under the same conditions by simulation methods. FEM analysis results show that using shape electrode type, current density distribution is very concentrated. And also by micro array pattern film, desired current density which is needed for electrochemical machining could be obtained easily. More precise electrochemical machining can be available by controlling the current density between the suitable type and invar alloy.

Design Features and Studies of Ammonia Electrothermal Microthrusters with Tubular Heating Elements for Small Space Vehicles

Background/Objectives: The article studies the definition of structural appearance of Electro Thermal Micro Thrusters (ETMT) with Tubular Heating Elements (THE) for Correcting Propulsion Systems (CPS) of maneuverable Small Space Vehicles (SSV). Methods: On the basis of an integrated approach we have defined structural appearance of ETMT with THE, conforming to the requirements to ensure minimum weight, manufacturability and maintainability. Findings: Structural diagrams of ETMT with THE having various lengths have been developed that provide increase in specific burst of power of ETMT in conditions of limited power consumption. Ammonia-operated prototypes of ETMT with THE have been manufactured and tested in a vacuum chamber under conditions most closely resembling the operational ones. The conducted experimental studies have shown the possibility of using ETMT with THE as part of CPS SSV in ETMT power consumption range varying from 60 to 70 W. Application/Improvements: These experimental studies are a continuation of works in creating ETMT of various designs and are of practical interest when developing CPS for maneuvering SSV 7 .

Solar heating by radiant floor: Experimental results and emission reduction obtained with a micro photovoltaic–heat pump system

Abstract An experimental research with a solar photovoltaic thermal (PVT) micro grid feeding a reversible air–water, 6 kW heating capacity heat pump, has been carried out from December 2012 to April 2013. Its purpose is to heat a laboratory that is used as a house prototype for the study of heating/cooling systems. It was built in accordance with the 2013 Spanish CTE, and has an area of 35 m 2 divided into two internal rooms: one of them housing the storage system, the solar controller, the inverter and the control system; the other one is occupied by three people. Its main thermal characteristics are: UA = 125 W/°C and a maximum thermal load about 6.0 kW at the initial time. The PVT field consists of 12 modules, with a total area of 15.7 m 2 and useful area of 14 m 2 . Each module is composed of 48 polycrystalline silicon cells of 243.4 cm 2 , which with a nominal efficiency 14% can generate a power of 180 W, being the total nominal power installed 2.16 kW. The PV system stores electricity in 250 Ah batteries from where is converted from DC to AC through a 3.0 kW inverter that feeds the heat pump. This works supplying 840 l/h of hot water at 35–45 °C to the radiant floor. The data storing system is recording variables such as solar radiation; temperatures; input power to batteries; heat produced; heat transferred by the radiant floor; heat pump’s COP; isolated ratio; and solar fraction. The objective of this work is to present and discuss the experimental results and the emission reduction of CO 2 obtained during the period from 01/12/2012 to 30/04/2013, including the detailed results of two representative days of Madrid’s climate: 28/12/2012 using only PV electricity and 21/01/2013 mixing PV and conventional electricity. The heat pump worked with a maximum COP about 6 when the difference of temperatures T C – T F was maximum, being the seasonal COP about 3.2. The period efficiency to DC electricity generation of the PV field was 9.2% and the efficiency to conversion to AC electricity to drive the heat pump was 5.7%. The global efficiency of solar conversion into heat was 18.2%, the isolation ratio was 69.3%, and the solar fraction about 65.3%. The saving emissions were 836 kgCO 2 /period in the case of a Gasoil boiler substitution and 574 kgCO 2 /period in the case of a Natural Gas boiler substitution. The heat pump contains 1.7 kg of refrigerant R410A with a GWP of 3400 kg equivalent CO 2 to IHT of 20 years. The emission of R410A to atmosphere was 0.031 kg in 13 months, being the equivalent mass of CO 2 about 106 kg. The thermal component of the modules field has not been used.

J2220301 ヘルスケアモニタリングのためのVO2熱量センサ

Biomolecules monitoring methods has been studied for the management of diseases like diabetes or hyperlipidemia for several decades. In this study, we report on a novel high sensitive electrochemical therml micro sensor based on VO_2 for an enzymatic healthcare monitoring system. In the process of glucose oxidation with the catalysis of enzyme, heat will be generated, which can be measured by a high sensitive thermal micro sensor so that the concentration of glucose solution can be calculated. A VO_2 thin film is used as a material of thermal micro sensor due to its high temperature coefficient of resistance of 15000 ppm/℃. The VO_2 thermal micro sensor is fabricated by the technology of MEMS with high temperature resolution of 0.299 mV/√Hz. This sensor has been utilized for the estimation of glucose concentration as an example. The result of glucose estimation indicates that the time rate of the output signal has positive correlation with glucose solution concentraitons.

29pm1-E-1 単一層による多軸熱マイクロアクチュエータのための梁の形状設計

29pm1-E-1 単一層による多軸熱マイクロアクチュエータのための梁の形状設計

Key Technologies of Heterojunction Solar Cell and Module Manufacturing

ABSTRACTThe a-Si/c-Si Heterojunction Technology (HJT) or Heterojunction with intrinsic thin layer (HIT) solar cell have been fabricated in mass production，the average conversion efficiency of HJT solar cells with 3 bus bar, 5 bus bar and smart wire structures have reached 20%, 21% and 22% respectively. One of the biggest obstructions for HIT module manufacturing is the Cell-to-Module (CTM) stringing process where much power loss happened due to high temperature. The higher temperature in stringing process makes passivation quality worse and introduces much more defects. In this article, we present our investigation on CTM string connection methods, especially on which undergo low temperature to avoid thermal micro damage on cell’s functional structure. Several kinds of string connection are elaborated. The discussion will give some directions for further laboratory research and HJT manufacturing.

Structural View Study on Diamond and Copper Bonding with AlNi Micro/nano Multilayers

Abstract A novel high thermal conductivity joining between diamond heat sink and light emitting diode (LED) chip was investigated. AlNi nano/micro-multilayers were fabricated and used to test the bonding of copper and diamond by self-propagation. The thermal analysis results and micro structure observation show that the bilayer (one alternative sputtering period of aluminium and nickel layers) of the mulilayer will influence the heat release of propagation reaction, and hence help to control the bonding process with steady. The influence of the vanadium addition and the magneto-conductivity of nickel element on the structures of the multilyers were also discussed, which has relation with the bilayer either. The quality of the diamond-copper joint by nano-multilayer bonding is better than that of the silver glue bonding in shearing strength and thermal conductivity

Synthesis of carbon nanotubes using Cu-Cr-O as catalyst by chemical vapor deposition

A novel powder catalyst Cu-Cr-O applied to the synthesis of carbon nanotubes (CNTs) was developed, which was prepared via ammonia precipitation method. Techniques of thermo-gravimetric/differential scanning calorimeter (TG-DSC), X-ray diffraction (XRD) as well as scanning electron microscopy (SEM) and transmission electron microscopy (TEM) have been employed to characterize the thermal decomposition procedure, crystal phase and micro structural morphologies of the as-synthesized materials, respectively. The results show that carbon nanotubes are successfully synthesized using Cu-Cr-O as catalyst when the precursors are calcined at 400, 500, 600, and 700 °C. The results indicate that the calcination of the Cu-Cr-O catalyst at 600 °C is an effective method to get MWCNT with few nano-tube defects or amorphous carbons.

Design and Analysis of Electro thermally Actuated Microgripper

Micro-Electro-Mechanical Systems (MEMS) technology offers the opportunity to produce mechanical, electromechanical, and electrochemical devices with the same unprecedented levels of miniaturization, and functionality as modern Very Large Scale Integrated (VLSI). Micro grippers are used for manipulation of biological samples, for assembling of micro parts and for micro assembly. Electro thermal micro grippers are promising tools enabling assembly and manipulation of nano-scale structures. In this paper MEMS based U-shaped thermally actuated micro-gripper is designed using two hot and one cold arm type thermal actuator. Then the effect of coefficient of thermal expansion and poisson’s ratio on stress for thermally actuated micro-gripper is analyzed and the results shows that the stress increases with the increase in coefficient of thermal expansion and the stress decreases with the increase in poisson’s ratio.