Harsh Applications Research Articles

Boosting Point Set-Based Network with Optimal Transport Optimization for Oriented Object Detection

When handling complex remote sensing scenarios, rotational angle information can improve detection accuracy and enhance algorithm robustness, providing support for fine-grained detection. Point set representation is one of the most commonly used methods in arbitrary-oriented object detection tasks, leveraging discrete feature points to represent oriented targets and achieve high accuracy in angle prediction. However, due to the inherent discreteness of point set representation, it is prone to significant impact from isolated points and representational ambiguity in harsh application scenarios, leading to inaccurate detection. To address this issue, an efficient aerial object detector named BE-Det is proposed, which uses the optimal transport (OT) strategy to constrain the positions of isolated points. Additionally, a candidate point set quality evaluation scheme is designed to effectively assess the quality of candidate point sets. Experimental results on two challenging aerial datasets demonstrate that the proposed method outperforms several advanced detection methods.

A Robust Core-Shell Nanofabric with Personal Protection, Health Monitoring and Physical Comfort for Smart Sportswear.

Smart textiles with a high level of personal protection, health monitoring, physical comfort, and wearing durability are highly demanded in clothing for harsh application scenarios, such as modern sportswear. However, seamlessly integrating such a smart clothing system has been a long-sought but challenging goal. Herein, based on coaxial electrospinning techniques, a smart non-woven textile (Smart-NT) integrated with high impact resistance is developed, multisensory functions, and radiative cooling effects. This Smart-NT is comprised of core-shell nanofibers with an ionic conductive polymer sheath and an impact-stiffening polymer core. The soft smart textile, with a thickness of only 800µm, can attenuate over 60% of impact force, sense pressure stimulus with sensitivity up to 201.5 kPa-1, achieve temperature sensing resolution of 0.1°C, and reduce skin temperature by ≈17°C under a solar intensity of 1kWm-2. In addition, the stretchable Smart-NT is highly durable and robust, retaining its multifunction features over 10000 bending and multiple washing cycles. Finally, application scenarios are demonstrated for real-time health monitoring, body protection, and physical comfort of smart sportswear based on Smart-NT for outdoor sports. The strategy opens a new avenue for seamless integration of smart clothing systems.

A non-absorption-loss immune TDLAS sensor for online Mach number evaluation in supersonic flows

Tunable diode laser absorption spectroscopy (TDLAS) techniques are widely used in combustion monitoring by using direct absorption spectroscopy (DAS). However, the DAS method is sensitive to laser intensity fluctuations and fails to work in harsh application cases. A non-absorption-loss immune TDLAS sensor was proposed for robust online evaluation of Mach number from temperature and speed in supersonic flows and in situ validated on a scramjet. Spectral lines of H2O at 7185.58 and 7444.35 cm−1 were selected to perform evaluations of target molecules, i.e., of water vapor. In highly turbulent supersonic flows of Mach 2.8, the proposed TDLAS sensor has improved the signal-to-noise ratio (SNR) of the transmitted laser intensity by about 6.46 dB, compared to the conventional single-ended TDLAS sensor. When the ramjet was running stably, the average Mach number was 2.82, and standard deviations of the Mach number were less than 0.09. Relative errors of measured Mach numbers were less than 1.39 %. The proposed sensor monitors the entire ramjet engine process from ignition to propellant cut-off at a rate of 5 kHz and yields detailed insights for ramjet performance evaluation.

Effect and mechanism of ionic liquid-polymer composite coating on enhancing hydrogen embrittlement resistance of X80 pipeline steel for hydrogen blended natural gas transportation

Blending hydrogen into existing natural gas pipelines is a cost-effective method for large-scale hydrogen transportation. However, high hydrogen ratios cause hydrogen embrittlement in pipeline steel, limiting transportation efficiency. Due to complex structures and harsh application conditions, existing coatings are difficult to apply on pipelines. To tackle such issues, we propose an ionic liquid-polymer composite coating using epoxy resin as coating substrate, based on the competitive adsorption of methane and hydrogen on pipeline steel. Ionic liquids with high methane selectivity were selected via quantum chemical calculation. The protective effect of coatings was characterized using hydrogen pre-charging constant strain tensile tests. Simulation and experimental results demonstrate that epoxy resin coatings reduce hydrogen embrittlement in X80 steel. Modified with selective CH4/H2 permeability ionic liquids, the epoxy resin coating enhances methane and hydrogen competitive adsorption on the steel surface, improving hydrogen embrittlement resistance. This novel coating offers a viable solution for achieving safe and high ratio hydrogen blended transportation in natural gas pipeline.

Superhydrophobic Tensile Designability of Silicone Rubber Composites.

Silicone rubber has broad applications in the field of industrial engineering due to its stable physical and chemical properties. However, the superhydrophobic properties, of silicone rubber, especially large deformation superhydrophobic properties, were not satisfactory for many harsh application environments and complex engineering structures. Here, we report the preparation of superhydrophobic tensile designable silicone rubber composites by a mixed deposition process that included powder deposition and smoke deposition. The infrared test showed that the deposited powder from silicone rubber combustion was mainly composed of SiO2 and short chain siloxane. The mixed deposited surface with a rich micro-nanostructure, which was the key to the formation of superhydrophobic properties. The water contact angle (WCA) and sliding angle (SA) of coating surface could reach 157.6° and 5° ± 1°, respectively, and the tensile designability of superhydrophobic surface is closely related to the prestretched process. In addition, bounce tests, high temperature tests, and solvent resistance tests showed the application potential of modified silicone rubber composites in the field of engineering.

High-temperature hydrogen sensor based on MOFs-derived Mn-doped In2O3 hollow nanotubes

Developing high-temperature hydrogen (H2) sensors with fast response speed is urgently demanded in harsh application environments, especially for chemical industries and the aerospace field. Herein, we have reported a facile strategy to synthesize Mn-doped In2O3 hollow nanotubes (Mn-In2O3) by solvothermal and annealing route using In-MOFs as precursors. The experimental results indicate that the obtained products possess hollow nanotube structures with plenty of holes and Mn doping greatly boosts the gas-sensing performance of In2O3-based sensors towards H2. In particular, the responses of 3 mol% Mn-In2O3 are 2.57 and 2.3 towards 50 ppm H2 at 360 °C and 400 °C, respectively, which are much higher than those of bare In2O3 hollow nanotubes. Besides, the sensor based on 3 mol% Mn-In2O3 exhibits a low limit of detection (25 ppb), excellent selectivity, rapid response/recovery speed (∼4 and ∼15 s@20 ppm), and excellent stability at high temperature (360 °C). Such enhancement of H2-sensing properties can be put down to the hollow structure derived from In-MOFs and abundant oxygen vacancy defects produced by Mn doping. The Mn-In2O3 hollow nanotubes could be regarded as promising materials for selectively detecting H2 in a wide range of concentrations.

Multidimensional Evaluation Methods for Deep Learning Models in Target Detection for SAR Images

As artificial intelligence technology advances, the application of object detection technology in the field of SAR (synthetic aperture radar) imagery is becoming increasingly widespread. However, it also faces challenges such as resource limitations in spaceborne environments and significant uncertainty in the intensity of interference in application scenarios. These factors make the performance evaluation of object detection key to ensuring the smooth execution of tasks. In the face of such complex and harsh application scenarios, methods that rely on single-dimensional evaluation to assess models have had their limitations highlighted. Therefore, this paper proposes a multi-dimensional evaluation method for deep learning models used in SAR image object detection. This method evaluates models in a multi-dimensional manner, covering the training, testing, and application stages of the model, and constructs a multi-dimensional evaluation index system. The training stage includes assessing training efficiency and the impact of training samples; the testing stage includes model performance evaluation, application-based evaluation, and task-based evaluation; and the application stage includes model operation evaluation and model deployment evaluation. The evaluations of these three stages constitute the key links in the performance evaluation of deep learning models. Furthermore, this paper proposes a multi-indicator comprehensive evaluation method based on entropy weight correlation scaling, which calculates the weights of each evaluation indicator through test data, thereby providing a balanced and comprehensive evaluation mechanism for model performance. In the experiments, we designed specific interferences for SAR images in the testing stage and tested three models from the YOLO series. Finally, we constructed a multi-dimensional performance profile diagram for deep learning object detection models, providing a new visualization method to comprehensively characterize model performance in complex application scenarios. This can provide more accurate and comprehensive model performance evaluation for remote sensing data processing, thereby guiding model selection and optimization. The evaluation method proposed in this study adopts a multi-dimensional perspective, comprehensively assessing the three core stages of a model’s lifecycle: training, testing, and application. This framework demonstrates significant versatility and adaptability, enabling it to transcend the boundaries of remote sensing technology and provide support for a wide range of model evaluation and optimization tasks.

The Effect of Epoxy Resin on the Infiltration of Porous Metal Parts Formed through Laser Powder Bed Fusion

Laser powder bed fusion (L-PBF) additive manufacturing technology can print multi-material parts with multiple functions/properties, and has great potential for working in harsh application environments. However, the metal blank formed by sintering metal powder material with binder added through L-PBF has an obvious porous structure and insufficient mechanical properties, and few studies have been conducted studying this. In this paper, epoxy resin was used to impregnate the blank of porous metal parts formed by L-PBF with iron-based powder material at a certain temperature, and a cross-linked curing reaction was carried out with three kinds of phenolic resin in different proportions under the action of a curing agent, so as to fill the pores and achieve the desired mechanical properties. The characteristic peaks of each group of epoxy resin were characterized using Fourier transform infrared spectroscopy (FT-IR) and H-nuclear magnetic resonance (1H-NMR) spectrums. The microstructure, decomposition temperature, and residue of four epoxy resin dispersion systems were analyzed with a scanning electron microscope (SEM), a thermal gravimetric analyzer (TGA), and derivative thermogravimetry (DTG). The results show that the density of the porous metal parts was obviously improved, the heat resistance temperature of the parts could reach 350 °C, and the tensile strength of the sample after EP2-1 impregnation was increased by 4–6 times after curing at 160 °C for 6 h. Therefore, the use of an epoxy resin dispersion system can increase the porosity of L-PBF porous metal parts, but can also significantly improve their mechanical properties, which can help them to meet the requirements of applications as model materials, biological materials, and functional materials to provide a feasible solution.

Thermal-to-Electrical Conversion Based on Salinity Gradient Driven by Evaporation.

Constructing concentration differences between anions and cations at the ends of an ionic conductor is an effective strategy in electricity generation for powering wearable devices. Temperature gradient or salinity gradient is the driving force behind such devices. But their corresponding power generation devices are greatly limited in actual application due to their complex structure and harsh application conditions. In this study, a novel ionic concentration gradient electric generator based on the evaporation difference of the electrolyte is proposed. The device can be constructed without the need for semipermeable membranes, and operation does not need to build a temperature difference. As a demonstration, a PVA-Na ionic hydrogel is prepared as an electrolyte for the device and achieved a thermovoltage of more than 200mV and an energy density of 77.94 J m-2 at 323 K. Besides, the device exhibits the capability to sustain a continuous voltage output for a duration exceeding 1500min, as well as enabling charging and discharging cycles for 100 iterations. For practical applications, a module comprising 16 sub-cells is constructed and successfully utilized to directly power a light-emittingdiode. Wearable devices and their corresponding cell modules are also developed to recycle body heat.

Self-sustaining personal all-day thermoregulatory clothing using only sunlight

The human body must stay within a certain temperature range for comfort and safety. However, challenges for thermoregulatory clothing exist for harsh application scenarios, such as full day/night cycles, frigid polar regions, and space travel. We developed a flexible and sustainable personal thermoregulatory clothing system by integrating a flexible organic photovoltaic (OPV) module to directly acquire energy from sunlight and bidirectional electrocaloric (EC) devices. The flexible OPV-EC thermoregulatory clothing (OETC) can extend the human thermal comfort zone from 22°–28°C to 12.5°–37.6°C with a fast thermoregulation rate. The low energy consumption and high efficiency of the EC device allows for 24 hours of controllable and dual-mode thermoregulation with 12 hours of sunlight energy input. This self-powered wearable thermoregulatory platform has a simple structure, compact design, high efficiency, and strong self-adaptability with sunlight as the sole energy source.

Revealing the room temperature superplasticity in bulk recrystallized molybdenum

Body-centered cubic refractory metallic materials exhibit excellent high-temperature strength, but often suffer from brittle intergranular fracture due to the recrystallization-induced enrichment of trace elements at grain boundaries (GBs). Here, we report a fully-recrystallized pure molybdenum (Mo) material with room temperature (RT) superplasticity, fabricated by a facile method of powder metallurgy, Y-type hot rolling and annealing. By engineering the ultralow concentration of O at GBs, the inherent GB brittleness of Mo can be largely eliminated, which, in conjunction with high fractions of soft texture and low angle GBs, enables a significant development of ordered dislocation networks and the effective dislocation transmission across low angle GBs. Synergy of these factors greatly suppress the brittle intergranular fracture of Mo, contributing to an enhanced deformability of 108.7% at RT. These findings should have general implication for fabricating a broad class of refractory metals and alloys toward harsh applications.

Charge Dynamics Engineering Sparks Hetero-Interfacial Polarization for an Ultra-Efficient Microwave Absorber with Mechanical Robustness.

Microwave absorbers with high efficiency and mechanical robustness are urgently desired to cope with more complex and harsh application scenarios. However, manipulating the trade-off between microwave absorption performance and mechanical properties is seldom realized in microwave absorbers. Here, a chemistry-tailored charge dynamic engineering strategy is proposed for sparking hetero-interfacial polarization and thus coordinating microwave attenuation ability with the interfacial bonding, endowing polymer-based composites with microwave absorption efficiency and mechanical toughness. The absorber designed by this new conceptual approach exhibits remarkable Ku-band microwave absorption efficiency (-55.3dB at a thickness of 1.5mm) and satisfactory effective absorption bandwidth (5.0GHz) as well as desirable interfacial shear strength (97.5MPa). The calculated differential charge density depicts the uneven distribution of space charge and the intense hetero-interfacial polarization, clarifying the structure-performance relationship from a theoretical perspective. This work breaks through traditional single performance-oriented design methods and ushers a new direction for next-generation microwave absorbers.

Cryoforged nanotwinned CoCrNi medium-entropy alloy with exceptional fatigue property at cryogenic temperature

The extraordinary work hardening ability and fracture toughness of the face-centered cubic medium-entropy alloy (MEA) at cryogenic temperature make them good candidates for harsh applications. In this work, we developed a hierarchical twin architecture in coarse grained CoCrNi MEA using multidirectional cryoforging (MDCF) technique and low-temperature annealing. The unique substructure brought a notable enhancement in the cryogenic tensile strength-ductility balance, as well as an impressive 106-cycle fatigue strength of up to 1100 MPa at cryogenic temperature, which is superior to other cryogenic alloys. The exceptional fatigue property of MDCF-MEA is ascribed to the synergistic effect of high-density dislocations and a dense nanotwin/microband network, providing high strength and the ability to suppress local surface roughening and crack initiation. Our work demonstrates a practical route to further extend CoCrNi MEA for the cryogenic application.

Design of Microbial Corrosion Assessment Model for Protective Coatings based on Combined Weight TOPSIS

Instrumentation has a wide range of applications in various fields. In today’s rapid development of information technology and the economy, it plays an indispensable role. The application environment of instrumentation in many fields is complex and harsh. Therefore, the requirements for instrumentation materials are also more stringent. This paper mainly focuses on the special fields of aerospace, petrochemical, marine, and nuclear energy. The application status of instrumentation and its harsh application environment have been researched. This paper researched the main corrosion failure modes of instrumentation materials, and put forward suggestions and solutions for corrosion protection methods.

Fatigue Damage Monitoring for Mining Vehicles using Data Driven Models

The life and condition of a mine truck frame are related to how the machine is used. Damage from stress cycles is accumulated over time, and measurements throughout the life of the machine are needed to monitor the condition. This results in high demands on the durability of sensors, especially in a harsh mining application. To make a monitoring system cheap and robust, sensors already available on the vehicles are preferred rather than additional strain gauges. The main question in this work is whether the existing on-board sensors can give the required information to estimate stress signals and calculate accumulated damage of the frame. Model complexity requirements and sensors selection are also considered. A final question is whether the accumulated damage can be used for prognostics and to increase reliability. The investigation is performed using a large data set from two vehicles operating in real mine applications. Coherence analysis, ARX-models, and rain flow counting are techniques used. The results show that a low number of available on-board sensors like load cells, damper cylinder positions, and angle transducers can give enough information to recreate some of the stress signals measured. The models are also used to show significant differences in usage by different operators, and its effect on the accumulated damage.

Achieving lasting corrosion protection for superhydrophobic epoxy coatings with photothermal conversion property via constructing functionalized graphene nanoplatelet

Conferring versatility to the epoxy (EP) coating is highly desirable to achieve long-term corrosion resistance. In this work, a simple and effective strategy is reported to integrate corrosion protection, superhydrophobicity, and photothermal conversion into EP coating. Specifically, a functional filler based on graphene nanoplatelet is fabricated by the anchoring of polytannic acid and the grafting reaction of octadecylamine. The good interface compatibility, excellent adhesive strength (4.8 MPa), and stable superhydrophobicity (water contact angle of 152.4° and water sliding angle of 7.4°) provide a reinforced barrier effect (low water absorption and low permeability of oxygen and chloride ions), resulting in the impedance modulus of the composite coating being nearly three orders of magnitude higher than that of the pure EP coating after 28 days of immersion in 3.5 wt% NaCl solution. Furthermore, the surface temperature rises rapidly to 78.4 °C within 2 min under the sunlight of 200 mW/cm2, demonstrating the efficient photothermal conversion capability of the composite coating and accelerating the evaporation of water from the coating surface. Gratifying, the superhydrophobic property of the composite coating can be restored even after the salt spray test, which is attributed to the migration of long-chain alkyl under sunlight irradiation. Therefore, the prepared composite coating with photothermal conversion and superhydrophobic performance is expected to be a promising candidate for long-lasting corrosion protection under harsh application environments.

Surface Damage Identification of Wind Turbine Blade Based on Improved Lightweight Asymmetric Convolutional Neural Network

Wind turbine blades are readily damaged by the workplace environment and frequently experience flaws such as surface peeling and cracking. To address the problems of cumbersome operation, high cost, and harsh application conditions with traditional damage identification methods, and to cater to the wide application of mobile terminal devices such as unmanned aerial vehicles, a novel lightweight asymmetric convolution neural network is proposed. The network introduces a lightweight asymmetric convolution module based on the improved asymmetric convolution, which applies depthwise separable convolution and channel shuffle to ensure efficient feature extraction capability while achieving a lightweight design. An enhanced Convolutional Block Attention Module (CBAM) embedded with a spatial attention module with a selective kernel, enhances the acquisition of spatial locations of damage features by combining multi-scale feature information. Experiments are carried out to verify the efficacy and the generalizability of the network proposed for the recognition task. A comparison experiment of common lightweight networks based on transfer learning is also conducted. The experimental results show that the lightweight network proposed in this article has better experimental metrics, including 99.94% accuracy, 99.88% recall, and 99.92% precision.

Edge-Hosted Mn-N4-C12 Site Tunes Adsorption Energy for Ultralow-Temperature and High-Capacity Solid-State Zn-Air Battery

Robust operation of Zn-air batteries (ZABs) with high capacity and excellent energy efficiency is desirable for practical harsh applications, whose bottlenecks are mainly originated from the sluggish oxygen catalytic kinetics and unstable Zn|electrolyte interface. In this work, we synthesized the edge-hosted Mn-N4-C12 coordination supported on N-doped defective carbon (Mn1/NDC) catalyst, exhibiting a good bifunctional performance of the oxygen reduction/evolution reaction (ORR/OER) with a low potential gap of 0.684 V. Theoretical calculation reveals that the edge-hosted Mn-N4-C12 coordination displayed the lowest overpotential of the ORR/OER owing to the decreased adsorption free energy of OH*. The Mn1/NDC-based aqueous ZABs deliver impressive rate performance, ultralong discharging lifespan, and excellent stability. Notably, the assembled solid-state ZABs demonstrate a high capacity of 1.29 Ah, a large critical current density of 8 mA cm-2, and robust cycling stability with excellent energy efficiency at -40 °C, which should be attributed to the good bifunctional performance of Mn1/NDC and anti-freezing solid-state electrolyte (SSE). Meanwhile, the zincophilic nanocomposite SSE with high polarity accounts for the stable Zn|SSE interface compatibility. This work not only highlights the importance of the atomic structure design of oxygen electrocatalysts for ultralow-temperature and high-capacity ZABs but also spurs the development of sustainable Zn-based batteries at harsh conditions.

Self-healing behaviors of metallized high-temperature dielectric films for capacitor applications

High-temperature metallized film capacitors (MFCs) are urgently desired in harsh application environments. Although there are a large number of research on polymer dielectrics with satisfactory energy storage property and excellent thermal resistance, it is not clear about the self-healing performance which is the key factor determining whether they can be applied in practice. In this paper, the self-healing behaviors of the metallized high-temperature dielectric films of poly (ethylene 2,6-naphthalate) (PEN), poly (ether ketone) (PEEK) and polyimide (PI) have been explored. Specifically, the influence of polymer chemistry, sheet resistance and interlayer pressure on self-healing process is analyzed in detail. It is found that the high carbon content in PI leads to the self-healing failure at low sheet resistance, though it displays small self-healing energy at high sheet resistance. The probability of successful self-healing of the metallized PEEK film is greatly reduced at high interlayer pressure. In addition, high self-healing energy which would lead to the fast ageing of MFC is obtained in PEEK. Fortunately, PEN with relatively low carbon content and the aliphatic-aromatic alternating structure shows brilliant self-healing ability at different sheet resistances and interlayer pressures with reasonable self-healing energy. Hence, PEN may be a promising candidate for high-temperature MFC from the perspective of self-healing.

Early Strength Evolution of Cement Grouts Adopted in Reinforced Concrete Subjected to Na2SO4 Corrosion

Due to the harsh application environment, sodium sulfate corrosion poses a considerable threat to the performance of reinforced concrete. Considering high fluidization and early strength cement grouts (HECG) are widely adopted in the repair engineering of reinforced concrete, HECG are also subjected to the action of corrosive substances. Even though numerous research results disclosed the effect of sodium sulfate corrosion on the performance and the degradation mechanisms of conventional cement grouts, the degradation mechanisms of HECG under sodium sulfate corrosion are still to be studied because HECG have the exceptional characteristics of high fluidization and early strength that conventional cement grouts do not have. Hence, the compressive and flexural strengths of HECG after corrosion with different sodium sulfate solution concentrations and corrosion times were tested in this study. Moreover, the evolution of the microstructure of HECG in the process of corrosion was analyzed with a Scanning Electron Microscope (SEM) test. The changes in the hydration products were investigated through the X-ray diffraction (XRD) test and the Differential Scanning Calorimeter (DSC) test. Consequently, the degradation mechanisms of HECG in the case of different sodium sulfate solution concentrations and corrosion times were revealed. The results indicate that the corrosion of sodium sulfate and hydration exists simultaneously when the corrosion time is less than 7 days. When the corrosion time is 14 days, the hydration of HECG was complete. The main source of the early strength of HECG is that the C-S-H gel crosses and clings to form a solid and compact whole in three-dimensional space. The effect of Na2SO4 on the early strength formation of HECG is that the corrosion of Na2SO4 can postpone the conversion of CH crystal into C-S-H gel and damage the generated CH crystal. This study on the degradation mechanisms of HECG exposed to sodium sulfate corrosion can provide new ideas for sulfate resistance and durability design of HECG.