Search Results (17)

Drop-on-demand (DoD) printing is an additive manufacturing technique that utilizes functional inks containing nanoparticles (NPs) to fabricate electronic circuits or devices on a variety of substrates. One of the most promising applications for such technology is the aerospace industry, due to the capability of this method to fabricate custom low-weight geometric films. This work evaluates the performance of a gold (Au) nanoparticle (NP)-based film printed on a ceramic substrate for avionics applications, following the environmental temperature guidance of the Radio Technical Commission for Aeronautics (RTCA) DO-160. Experimental results show that the Au films, printed on alumina substrates, successfully survived the environmental temperature procedures for airborne equipment. The thermal coefficient of resistance (TCR) of the films was measured to be $2.7\times {10}^{-3} {°\mathrm{C}}^{-1}.$ Full article

Considering the presence of airborne viruses, there is a need for renovation in refuse chutes, regarded as the first step in recycling household waste in buildings. This study aimed to revise the design of existing refuse chutes in light of the challenging experiences in waste management and public health during the coronavirus pandemic. This research primarily focused on the risks posed by various types of coronaviruses, such as the novel coronavirus (COVID-19) and acute respiratory syndrome (SARS and SARS-CoV), on stainless steel surfaces, with evidence of their survival under certain conditions. Refuse chutes are manufactured from stainless steel to resist the corrosive effects of waste. In examining the existing studies, it was observed that Casanova et al. and Chowdhury et al. found that the survival time of coronaviruses on stainless steel surfaces decreases as the temperature increases. Based on these studies, mechanical revisions have been made to the sanitation system of the refuse chute, thus increasing the washing water temperature. Additionally, through mechanical improvements, an automatic solution spray entry is provided before the intake doors are opened. Furthermore, to understand airflow and clarify flow parameters related to airborne infection transmission on residential floors in buildings equipped with refuse chutes, a computational fluid dynamics (CFD) analysis was conducted using a sample three-story refuse chute system. Based on the simulation results, a fan motor was integrated into the system to prevent pathogens from affecting users on other floors through airflow. Thus, airborne pathogens were periodically expelled into the atmosphere via a fan shortly before the intake doors were opened, supported by a PLC unit. Additionally, the intake doors were electronically interlocked, ensuring that all other intake doors remained locked while any single door was in use, thereby ensuring user safety. In a sample refuse chute, numerical calculations were performed to evaluate parameters such as the static suitability of the chute body thickness, static compliance of the chute support dimensions, chute diameter, chute thickness, fan airflow rate, ventilation duct diameter, minimum rock wool thickness for human contact safety, and the required number of spare containers. Additionally, a MATLAB code was developed to facilitate these numerical calculations, with values optimized using the Fmincon function. This allowed for the easy calculation of outputs for the new refuse chute systems and enabled the conversion of existing systems, evaluating compatibility with the new design for cost-effective upgrades. This refuse chute design aims to serve as a resource for readers in case of infection risks and contribute to the literature. The new refuse chute design supports the global circular economy (CE) model by enabling waste disinfection under pandemic conditions and ensuring cleaner source separation and collection for recycling. Due to its adaptability to different pandemic conditions including pathogens beyond coronavirus and potential new virus strains, the designed system is intended to contribute to the global health framework. In addition to the health measures described, this study calls for future research on how evolving global health conditions might impact refuse chute design. Full article

For advanced aircraft, the temperature environment inside the cabin is very severe due to the high flight speed and the compact concentration of the electronic equipment in the cabin. Accurately predicting the temperature environment induced inside the cabin during the flight of the aircraft can determine the temperature environment requirements of the onboard equipment inside the cabin and provide an accurate input for the thermal design optimization and test verification of the equipment. The temperature environment of the whole aircraft is divided into zones by the cluster analysis method; the heat transfer mechanism of the aircraft cabin is analyzed for the target area; and the influence of internal and external factors on the thermal environment is considered to establish the temperature environment prediction model of the target cabin. The coefficients of the equations in the model are parameterized to extract the long-term stable terms and trend change terms; with the help of the measured data of the flight state, the model coefficients are determined by a stepwise regression method; and the temperature value inside the aircraft cabin is the output by inputting parameters such as flight altitude, flight speed, and external temperature. The model validation results show that the established temperature environment prediction model can accurately predict the change curve of the cabin temperature during the flight of the aircraft, and the model has a good follow-up performance, which reduces the prediction error caused by the temperature hysteresis effect. For an aircraft, the estimated error is 2.8 °C at a confidence level of 95%. Engineering cases show that the application of this method can increase the thermal design requirements of the airborne equipment by 15 °C, increase the low-temperature test conditions by 17 °C, and avoid the problems caused by an insufficient design and over-testing. This method can accurately predict the internal temperature distribution of the cabin during the flight state of the aircraft, help designers determine the thermal design requirements of the airborne equipment, modify the thermal design and temperature test profile, and improve the environmental worth of the equipment. Full article

It is vital to maximize the safety of outdoor constructions, airplanes, and space vehicles by protecting against the impact of airborne debris from increasing winds due to climate change, or from bird strikes or micrometeoroids. In a widely-used compression-molded short glass fiber polyester bulk-molded compound (SGFRP-BMC) with 55% wt. CaCO₃ filler, the center of the mother panel has lower impact strength than the outer sections with solidification texture angles and short glass fiber (SGF) orientations being random from 0 to 90 degrees. Therefore, a new double-step process of: (1) reducing commercial fiber length without change in molding equipment; followed by a (2) 0.86 MGy dose of homogeneous low-voltage electron beam irradiation (HLEBI) to both sides of the finished samples requiring no chemicals or additives, which is shown to increase the Charpy impact value (a_uc) about 50% from 6.26 to 9.59 kJm⁻² at median-accumulative probability of fracture, P_f = 0.500. Shortening the SGFs results in higher fiber spacing density, S_f, as the thermal compressive stress site proliferation by action of the CTE difference between the matrix and SGF while the composite cools and shrinks. To boost impact strength further, HLEBI provides additional nano-compressive stresses by generating dangling bonds (DBs) creating repulsive forces while increasing SGF/matrix adhesion. Increased internal cracking apparently occurs, raising the a_uc. Full article

We conducted a pilot study to investigate air quality indoors in two classrooms and outdoors on the school grounds in a California community with historically high PM_2.5 (fine particulate matter, diameter < 2.5 μm). We used computer-controlled scanning electron microscopy of passive samples to identify major PM types, which were used to help interpret continuous PM_2.5 and black carbon sensor data. The five major PM types were sodium salt particles with sulfur, calcium, or chlorine; aluminosilicate dusts; carbonaceous combustion agglomerates; biogenic particles; and metal-rich particles. Based on morphological evidence of water droplets, the salt particles are hypothesized to be secondary aerosols formed via the reaction of sodium chloride fog droplets with sulfur from regional sources. The carbonaceous agglomerates had unusual morphologies consistent with low-temperature combustion and smoke from open-burning activities observed nearby. The passive PM sampler and continuous sensor results indicated lower concentrations in the classroom equipped with an air cleaner. Passive samples collected in one classroom exhibited enhanced PM_10–2.5 crustal particles and PM_2.5 metal particles, suggesting a potential local PM source in that room. Future study designs that enable longer passive sampling times would reduce detection limits and sample contamination concerns. The determination of major airborne particle types in a given environment makes this technique a useful and unique community exposure assessment tool, even in these limited-duration (48 h) deployments. Full article

At present, the research and application of aeromagnetic compensation are almost all based on the Tolles–Lawson (T–L) model. With the development of unmanned aerial vehicles (UAVs), the number of intelligent electronic devices in UAVs is increasing, and the magnetic environment of the platform is becoming more and more complicated. Research shows that the magnetic interference caused by airborne electronic equipment has been very significant, sometimes even reaching 100 nT. The traditional airborne magnetic compensation method based on the T–L model cannot effectively compensate the magnetic interference caused by airborne electronic equipment. Aiming at the problem of magnetic interference of airborne electronic equipment of UAVs, this paper analyzes the origin of magnetic interference of airborne electronic equipment using experiments, and it was found that it is related to the power supply current, and the characteristics of magnetic interference are similar to permanent magnet materials. Based on this feature, we eliminated the magnetic interference caused by the working current of airborne equipment by establishing a linear compensation model based on the current’s source. The experimental data show that the current interference source model proposed in this paper can effectively compensate the magnetic interference generated by airborne electronic equipment and the compensation improvement ratio (IR) is greater than 10. Full article

Much agricultural and forestry land in the world cannot be accessed by ground planting equipment because of traffic, terrain, and other factors. This not only causes low efficiency and waste of resources, but also has a negative impact on the sustainable development of forestry. Therefore, it is significant to develop an accurate, efficient, and energy-saving aerial precision seeding system using unmanned aerial vehicle (UAV) technology to meet the actual needs of forestry planting. In this study, a UAV precision afforestation system with a GUI, afforestation UAV, positioning system, and information interaction system were developed using related approaches such as electronic information technology. The UAV airborne seeding device added a control circuit and electronic chip to control the launching speed of the cylinder and seed loading speed, while the UAV flight speed is jointly controlled to accurately control the UAV seeding depth and seed spacing. The experimental results showed that the maximum seeding depth of the afforestation equipment was 6.7 cm. At the same seed launching speed, the smaller the content of sand and gravel in the soil, the higher the sowing qualification index, and the greater the sowing depth. The average absolute error of dynamic route RTK-automatic control seeding position accuracy was 7.6 cm, and the average error of static position hovering seeding was 7.7 cm. Resulting from the separate sown experiments of three crops, the sowing pitch angle of 75° gave the highest germination rate. The UAV seeding device has a low missing seed index and a qualified seeding index of more than 95% at 120 r/min seeding speed. The seeding device studied in this paper has a good seeding effect, can meet the requirements of afforestation, and provides a new technical means for managing forest and plant resources. Full article

The immobilization of titanium dioxide, particularly commercial TiO₂ P25, on the surface of recycled rubber tiles presents a solution for achieving passive air protection. A completely new purpose for tiles was obtained by addressing air pollution and related health issues. Modified rubber tiles were prepared using a sol–gel method with three different proportions of TiO₂ (2, 4, and 10 g) in the solution. The nature of TiO₂ nanoparticles and their respective binding on the tile surface was determined using scanning electron microscopy (SEM) equipped with electron dispersion X-ray spectrometry (EDS) and Fourier-transform infrared (FTIR) spectroscopy. The SEM-EDS results showed that the most successful immobilization was achieved with the lowest amount of TiO₂ in the sol–gel solution. The FTIR results confirmed a band at 950 cm⁻¹ that was attributed to the Ti-O-Si bond. The stability and environmental impact of the treated rubber substrates were investigated by a leaching test. Photocatalytic oxidation was confirmed by the oxidation of NH₃ to N₂. Based on the results obtained, rubber substrates with an addition of 2 g of TiO₂ have demonstrated prospects for further tests of the photocatalytic degradation of airborne pollutants. Full article

With the rapid development of unmanned aerial vehicles (UAVs) technology, using UAVs for magnetic surveys is a booming branch. However, the magnetic interference generated by the UAV hinders the further application of UAV magnetic survey systems. In addition to the interference caused by the UAV maneuvering, the dynamic interference of airborne equipment has also been found and become one of the factors restricted by the detection accuracy of magnetic surveys. This paper proposes a multi-source two-channel linear time-invariant (MTLI) correlation model, considering the maneuvering magnetic interference and airborne equipment magnetic interference. The magnetic interference can be estimated and compensated by interference correlation without current sensors. Compared with the traditional aeromagnetic compensation process and other compensation methods considering the magnetic interference of airborne equipment, the proposed method can provide stable compensation effects in maneuvers and smooth flight, and the workflow is simple and fast. The actual flight experiment is conducted, and the results show that the two kinds of UAV interference fields are suppressed significantly with a root mean square error of 0.0062 and 0.0296 nT in smooth flight and maneuvering flight. Full article

We present the design, fabrication, and testing of a drone-mountable gas sensing platform for environmental monitoring applications. An array of graphene-based field-effect transistors in combination with commercial humidity and temperature sensors are used to relay information by wireless communication about the presence of airborne chemicals. We show that the design, based on an ESP32 microcontroller combined with a 32-bit analog-to-digital converter, can be used to achieve an electronic response similar, within a factor of two, to state-of-the-art laboratory monitoring equipment. The sensing platform is then mounted on a drone to conduct field tests, on the ground and in flight. During these tests, we demonstrate a one order of magnitude reduction in environmental noise by reducing contributions from humidity and temperature fluctuations, which are monitored in real-time with a commercial sensor integrated to the sensing platform. The sensing device is controlled by a mobile application and uses LoRaWAN, a low-power, wide-area networking protocol, for real-time data transmission to the cloud, compatible with Internet of Things (IoT) applications. Full article

This study aimed to elucidate the physicochemical characteristics and occupational exposure of silica powder and airborne particles as byproducts generated from the first scrubbers of chemical vapor deposition and diffusion processes during maintenance in a semiconductor facility sub fab to reduce unknown risk factors. The chemical composition, size, morphology, and crystal structure of powder and airborne particles as byproducts were investigated using a scanning electron microscopy and transmission electron microscopy equipped with an energy dispersive X-ray spectroscopy, and an X-ray diffraction. The number and mass concentration measurements of airborne particles were performed by using an optical particle sizer of a direct-reading aerosol monitor. All powder and airborne particle samples were mainly composed of oxygen (O) and silicon (Si), which means silica. The byproduct particles were spherical and/or nearly spherical and the particle size ranged from 10 to 90 nm, based on primary particles. Most of the particles were usually agglomerated within a particle size range from approximately 100 nm to 35 µm. In addition, most of the powder samples exhibited diffraction patterns with a broad and relatively low intensity at 2θ degrees 21.6–26.7°, which is similar to that of pure amorphous silica. The above results show the byproduct particles are amorphous silica, which are considered a less toxic foam compared to crystalline silica. The number and mass concentrations of PM10 (particles less than 10 µm in diameter) ranged from 4.250–78.466 particles/cm³ and 0.939–735.531 µg/m³, respectively. In addition, 0.3–1.0 and 2.5–10 µm particles occupied the highest portion of the number and mass concentrations, respectively. Meanwhile, several peak exposure patterns were observed at a specific step, which is the process of removing powder particles on the inner chamber and cleaning the chamber by using a vacuum cleaner and a clean wiper, during the maintenance task. Full article

The paper describes the influence of power electronics, energy processing, and emergency radio systems (ERS) immunity testing on onboard aircraft equipment and ground stations providing air traffic services. The implementation of next-generation power electronics introduces potential hazards for the safety and reliability of aircraft systems, especially the interferences from power electronics with high-power processing. The paper focuses on clearly identifying, experimentally verifying, and quantifiably measuring the effects of power electronics processing using switching modes versus the electromagnetic compatibility (EMC) of emergency radio systems with electromagnetic interference (EMI). EMI can be very critical when switching power radios utilize backup receivers, which are used as aircraft backup systems or airport last-resort systems. The switching power electronics process produces interfering electromagnetic energy to create problems with onboard aircraft radios or instrument landing system (ILS) avionics services. Analyses demonstrate significant threats and risks resulting from interferences between radio and power electronics in airborne systems. Results demonstrate the impact of interferences on intermediate-frequency processing, namely, for very high frequency (VHF) radios. The paper also describes the methodology of testing radio immunity against both weak and strong signals in accordance with recent aviation standards and guidance for military radio communication systems in the VHF band. Full article

In recent years, microelectronics technology has entered the era of nanoelectronics/integrated microsystems. System in Package (SiP) and System on Chip (SoC) are two important technical approaches for microsystems. The development of micro-system technology has made it possible to miniaturize airborne and missile-borne electronic equipment. This paper introduces the design and implementation of an aerospace miniaturized computer system. The SiP chip uses Xilinx Zynq^® SoC (2ARM^® + FPGA), FLASH memory and DDR3 memory as the main components, and integrates with SiP high-density system packaging technology. The chip has the advantages of small size and ultra-low power consumption compared with the traditional PCB circuit design. A pure software-based DDR3 signal eye diagram test method is used to verify the improvement inf the signal integrity of the chip without the need for probe measurement. The method of increasing the thermal conductive silver glue was used to improve the thermal performance after the test and analysis. The SiP chip was tested and analyzed with other mainstream aviation computers using a heading measurement of extended Kalman filter (EKF) algorithm. The paper has certain reference value and research significance in the miniaturization of the aviation computer system, the heat dissipation technology of SiP chip and the test method of signal integrity. Full article

With the continuous application of high-power electronic equipment in aircraft, highly efficient heat transfer technology has been emphasized for airborne applications. In this paper, a thermal management system based on an antifreeze liquid cooling loop and a vapor compression refrigeration loop is presented for high-power airborne equipment in a helicopter. The simulation models of the thermal management system are built in order to study its control strategy for the changing flight conditions. The antifreeze-refrigerant evaporator and air-refrigerant condenser are specially validated with the experimental data. A dual feedforward proportion integration differentiation and expert control algorithm are adopted in the inlet temperature of the cold plate and sub-cooling control of the refrigerant by regulating the compressor speed and the fan speed, respectively. A preheating strategy for antifreeze is set up to decrease its flow resistance in cold day conditions. The control strategy for the thermal management system is finally built based on the above control methods. In this paper, two extreme conditions are discussed, including cold and hot days. Both the simulation results show that the superheated, sub-cooling and antifreeze inlet temperature of the cold plate can be controlled at 3 to8 °C, −10 to −3 °C and 18 to22 °C, respectively. Under the same changing flight envelope, the coefficient of performance of the vapor compression refrigeration loop is relatively stable on the cold day, which is about 6, while it has a range of 2.58–4.9 on the hot day. Full article

The inductive proximity sensor (IPS) is applicable to displacement measurements in the aviation field due to its non-mechanical contact, safety, and durability. IPS can increase reliability of position detection and decrease maintenance cost of the system effectively in aircraft applications. Nevertheless, the specialty in the aviation field proposes many restrictions and requirements on the application of IPS, including the temperature drift effect of the resistance component of the IPS sensing coil. Moreover, reliability requirements of aircrafts restrict the use of computational-intensive algorithms and avoid the use of process control components. Furthermore, the environment of airborne electronic equipment restricts measurements driven by large current and proposes strict requirements on emission tests of radio frequency (RF) energy. For these reasons, a differential structured IPS measurement method is proposed in this paper. This measurement method inherits the numerical separation of the resistance and inductance components of the IPS sensing coil to improve the temperature adaptation of the IPS. The computational complexity is decreased by combining the dimension-reduced look-up table method to prevent the use of process control components. The proposed differential structured IPS is equipped with a differential structure of distant and nearby sensing coils to increase the detection accuracy. The small electric current pulse excitation decreases the RF energy emission. Verification results demonstrate that the differential structured IPS realizes the numerical decoupling calculation of the vector impedance of the sensing coil by using 61 look-up table units. The measuring sensitivity increased from 135.5 least significant bits (LSB)/0.10 mm of a single-sensing-coil structured IPS to 1201.4 LSB/0.10 mm, and the linear approximation distance error decreased from 99.376 μm to −3.240 μm. The proposed differential structured IPS method has evident comparative advantages compared with similar measuring techniques. Full article