Strong Reflection Research Articles

A Frequency Reconfigurable Antireflection Metasurface for GPR

Abstract The antireflection metasurface (AM) is employed in ground penetrating radar (GPR) to mitigate the strong reflection of electromagnetic waves at the air-ground interface due to impedance mismatch. However, due to constraints imposed by the relative bandwidth (RBW) and manufacturing processes, these layers tend to exhibit excessive thickness and bulky shape, narrow RBW, and fixed functionality in a passive configuration. This paper presents a novel, dual-band, independent wideband tuning, frequency reconfigurable AM based on varactor diodes with center frequencies of 1.35 GHz and 2.60 GHz. This metasuface possesses positive characteristics such as a single layer, the ultrathin thickness (0.03 \& 0.06$\lambda$), the wide RBW (43.3\% \& 27.4\%) and remarkable antireflection. The aforementioned metasurface achieves the described mechanisms and features through the destructive interference theory and the combine element technique. Numerical simulation results of surface currents and electric field energy power demonstrate the antireflection property. The equivalent electromagnetic parameter retrieval results also provide equivalent impedance conditions for non-perfect antireflection. The proposed AM samples demonstrates notable stepwise frequency reconfigurable characteristics in free-space experiments. The imaging effect after loading this AM is significantly improved in real-world GPR ballast roadbed anomaly detection experiments. This approach provides significant research value and promising prospects across various disciplines, including the stepped-frequency GPR, microwave imaging, and interdisciplinary fields.

Spectrally selective and thermally insulating hybrid nanofiber aerogel coolers for building energy conservation

With the advancement of worldwide carbon neutralization, passive radiative cooling (PRC) has attracted tremendous interest in energy conservation by dissipating heat into the ultracold outer space without any electricity consumption. Despite some progress has been made in tailoring spectral properties for PRC, it still remains a crucial challenge in fabricating efficient and low-cost coolers for building energy saving. Herein, hierarchical cellulose-based aerogel coolers consisting of beads-on-string structural electrospun nanofibers are manufactured for all-day and all-region energy saving by combining radiative cooling and thermal insulation in one design. The hierarchically porous architectures and well-designed chemical compositions endow the aerogels with strong solar reflectance (∼0.974), high mid-infrared emittance (∼0.985), and ultra-low thermal conductivity (0.0285 W (m K)−1), achieving a sub-ambient cooling of ∼8.24 °C during the daytime and ∼7.41 °C during the nighttime. The aerogels also exhibit exceptional compressive resiliency, anti-aging, and self-cleaning properties, promising for durable cooling under harsh conditions. The building energy simulations show that about 23.1 kWh m−2 of the total energy consumption per year can be saved if the aerogel coolers are widely deployed as building envelopes in China. This work provides new perspectives for the development of advanced aerogel coolers for future energy saving applications.

Method for Extracting Optical Element Information Using Optical Coherence Tomography

This study examines the measurement of film thickness, curvature, and defects on the surface or inside of an optical element using a highly accurate and efficient method. This is essential to ensure their quality and performance. Existing methods are unable to simultaneously extract the three types of information: thickness, curvature, and defects. Spectral-domain optical coherence tomography (SD-OCT), a non-invasive imaging technique with imaging depths down to the millimeter scale, provides the possibility of detecting the optical element components’ parameters. In this paper, we propose an error correction model for compensating delay differences in A-scan, field curvature, and aberration to improve the accuracy of system fitting measurements using SD-OCT. During data processing, we use the histogram-equalized gray stretching (IAH-GS) method to deal with strong reflections in the thin film layers inside the optics using individual A-scan averages. In addition, we propose a window threshold cutoff algorithm to accurately identify defects and boundaries in OCT images. Finally, the system is capable of rapidly detecting the thickness and curvature of film layers in optical elements with a maximum measurement depth of 4.508 mm, a diameter of 15 × 15 mm, a resolution of 5.69 microns, and a sampling rate of 70 kHz. Measurements were performed on different standard optical elements to verify the accuracy and reliability of the proposed method. To the best of our knowledge, this is the first time that thickness, curvature, and defects of an optical film have been measured simultaneously, with a thickness measurement accuracy of 1.924 µm, and with a difference between the calibrated and nominal curvature measurements consistently within 1%. We believe that this research will greatly advance the use of OCT technology in the testing of optical thin films, thereby improving productivity and product quality.

Solar-Adaptive Cooling Blocks Composed of Recycled Fabric.

Radiative cooling technologies have had a significant impact on advancing carbon neutrality efforts by significantly improving the passive cooling efficiency. The tandem of conduction and radiation enables solar-adaptive radiative cooling through the insulating effect of materials along with solar absorption, which affects the thermal state of materials and enhances radiative thermal transfer from the surface under solar irradiation. This enhancement is achieved by utilizing the porous polymeric structure of materials, which facilitates improved conduction pathways along with solar reflectance, while maintaining the effective emission of thermal radiation. In this particular scenario, blocks, which were made of recycled fibers, offer a great opportunity as solar-adaptive cooling materials, enabling their easy deployment for cooling applications. Herein, we have fabricated a porous block using fiber wastes that combines strong solar reflectance (92%) at the 1 μm region and high thermal infrared emittance (∼75%) at the 10 μm region. The combination of effective solar reflection and thermal infrared emission allows the fiber block to achieve a high cooling performance of approximately 68 W/m2 under solar irradiation. In addition, the fiber block works effectively for insulation during the night, thereby enhancing its heat retention capabilities. The economic and environmental advantages of the fiber block make it a cost-competitive and sustainable choice for near-market cooling technologies. This design is anticipated to expand the practical application range of passive cooling.

An Ultra-Broadband Electromagnetic Wave Absorbing ZrB2-Based Ceramic Composite Inspired by Barbule of Peacock.

Broadband electromagnetic wave (EMW) absorbing ceramic materials are highly required for the thermal parts of aerocraft. As members of ultrahigh temperature ceramics, ZrB2-based ceramics have great potential for applications in more extreme environments relative to the currently used silicon-based and oxide-based ceramics. However, ZrB2 is not among the traditional EMW absorbing material candidates due to its high conductivity, which induces the strong reflection of EMW due to the impedance mismatch with free space. Herein, ZrB2-based ceramic with a bionic microstructure inspired by peacock barbules is proposed. Boron nitride nanotubes acting as polarization centers inside the ZrB2-based material cause massive EMW dissipation. The ceramic shows an ultra-broadband absorption of 9.6GHz (<-10dB from 8.4 to 18GHz), almost covering the entire X and Ku bands, superior to the reported ceramics. The polarization centers successfully turn the ZrB2-based ceramic from EMW reflecting material to an excellent EMW absorbing material by the bionic barbule interspersed microstructure. The simulated metamaterial of the ceramic achieves an ultra-broad absorption (lower than -15dB) in the range of 2-40GHz. This work provides valuable insights for the development of broadband absorption material for high-temperature environments.

Enhancing RODNet detection in complex road environments based on ESM and ISM methods

In autonomous driving, accurately identifying traffic targets is crucial for ensuring the safe and reliable operation of autonomous vehicles. Millimeter-wave radar, known for its low cost, long detection range, and excellent performance under various weather conditions. Deep learning algorithms, particularly the radar object detection network (RODNet), have been effectively applied to radar target detection by analyzing the range-azimuth (RA) heatmaps that capture complex target features. However, the low angular resolution of radar RA heatmaps, combined with the high sensitivity of millimeter-wave radar to metal objects, makes adjacent targets prone to misdetection and increases the likelihood of misclassification of target types due to metal reflections from road obstacles. To address these issues, this paper proposes an innovative extension suppression method to enhance RA heatmaps, reducing interference between adjacent targets and significantly improving target resolution. Additionally, the paper incorporates Gaussian filtering, peak detection, and amplitude suppression algorithms to design an interference suppression method, accurately identifying and mitigating strong reflections from non-target regions, thereby improving detection efficiency in complex environments. The effectiveness and superiority of these methods have been fully validated, with AP improvements of 18% in overlapping scenarios, 2% in metal obstacle scenarios, and around 10% in high-speed scenarios compared to the latest methods.

Hue Guidance Network for Single Image Reflection Removal.

Reflection from glasses is ubiquitous in daily life, but it is usually undesirable in photographs. To remove these unwanted noises, existing methods utilize either correlative auxiliary information or handcrafted priors to constrain this ill-posed problem. However, due to their limited capability to describe the properties of reflections, these methods are unable to handle strong and complex reflection scenes. In this article, we propose a hue guidance network (HGNet) with two branches for single image reflection removal (SIRR) by integrating image information and corresponding hue information. The complementarity between image information and hue information has not been noticed. The key to this idea is that we found that hue information can describe reflections well and thus can be used as a superior constraint for the specific SIRR task. Accordingly, the first branch extracts the salient reflection features by directly estimating the hue map. The second branch leverages these effective features, which can help locate salient reflection regions to obtain a high-quality restored image. Furthermore, we design a new cyclic hue loss to provide a more accurate optimization direction for the network training. Experiments substantiate the superiority of our network, especially its excellent generalization ability to various reflection scenes, as compared with state-of-the-arts both qualitatively and quantitatively. Source codes are available at https://github.com/zhuyr97/HGRR.

Fabrication of core-shell Fe4N@C with sea-island structure by one-step nitriding method as efficient electromagnetic wave composite absorber

Porous structure design and magnetic-dielectric composite are effective ways to develop electromagnetic wave (EMW) absorbing materials with light-weight, thin-thickness, large effective absorption bandwidth (EAB), and strong reflection loss (RL). This article presents a simple one-step nitridation method for synthesizing Fe4N@C compounds with sea-island like and core-shell structures. The optimal RL value of Fe4N@C is up to -60.01dB, and the EAB (frequency range for RL< -10 dB) is 5GHz (11.1-16.1GHz) with a thickness of 1.9mm. The EAB reaches 5.5GHz (12.5-18GHz) when the matching thickness is 1.7mm. The multi-component design achieved excellent impedance matching properties. The carbon frame connects the core-shell particles to form a three-dimensional porous structure, providing multiple reflection losses. Therefore, this work provides a convenient way to design efficient and lightweight EMW absorbers with special structures.

Sedimentation-controlled double BSRs and implications for paleo hydrate dissociation in the Shenhu area, south China sea

Double/multiple bottom-simulating reflectors (BSRs) have been discovered worldwide, but their preservation and formation mechanism remain unclear because most studies are based on seismic data, lacking direct evidence like well logging data. This study introduces a novel well log-based interpretation of double BSR, suggesting that the secondary BSR (BSR2) is the interface between little residual gas and the overlying water-saturated sediment, and the free gas is trapped by capillary seals. The BSR2's amplitude is influenced by the nearby porosity, with lower porosity resulting in stronger reflections. Seismic attributes reveal a dynamic process of hydrate cycle that hydrate dissociation occurs above BSR2, followed by gas migrate to form a new BSR1. The upshift of BSR2 is mainly controlled by sedimentation rate, which varies across different regions, leading to larger upshifts in areas with higher sedimentation rates. Moreover, BSR2's upshift is negatively related to the reflection magnitude of BSR2, because rapidly depositing sediments with higher porosity and lower percolation threshold allow lesser gas sealed beneath the BSR2. Our findings suggest that double BSRs are predominantly formed in muddy sediments under rapid geological events like rapid sedimentation. However, each BSR can be preserved as well as observed to indicate that the BSR has existed for an extended period of time during which the geologic environment has been relatively stable, e.g., low sedimentation rates. This detailed sedimentation-controlled BSR adjustment provides new insights for the interpretation of double BSR and the paleo hydrate dissociation.

Resonant Metasurfaces with Van Der Waals Hyperbolic Nanoantennas and Extreme Light Confinement

This work reports on a metasurface based on optical nanoantennas made of van der Waals material hexagonal boron nitride. The optical nanoantenna made of hyperbolic material was shown to support strong localized resonant modes stemming from the propagating high-k waves in the hyperbolic material. An analytical approach was used to determine the mode profile and type of cuboid nanoantenna resonances. An electric quadrupolar mode was demonstrated to be associated with a resonant magnetic response of the nanoantenna, which resembles the induction of resonant magnetic modes in high-refractive-index nanoantennas. The analytical model accurately predicts the modes of cuboid nanoantennas due to the strong boundary reflections of the high-k waves, a capability that does not extend to plasmonic or high-refractive-index nanoantennas, where the imperfect reflection and leakage of the mode from the cavity complicate the analysis. In the reported metasurface, excitations of the multipolar resonant modes are accompanied by directional scattering and a decrease in the metasurface reflectance to zero, which is manifested as the resonant Kerker effect. Van der Waals nanoantennas are envisioned to support localized resonances and can become an important functional element of metasurfaces and transdimensional photonic components. By designing efficient subwavelength scatterers with high-quality-factor resonances, this work demonstrates that this type of nanoantenna made of naturally occurring hyperbolic material is a viable substitute for plasmonic and all-dielectric nanoantennas in developing ultra-compact photonic components.

Insights into the crustal and the magmatic feeding structure at the Payunia Volcanic Province highlighted by geophysical methods, in the retroarc of the Southern Central Andes

The Payunia Volcanic Province is a Quaternary volcanic plateau emplaced in the retroarc area in the northern Neuquén Mesozoic Basin, associated with a hydrocarbon system. At deeper levels, this basin is linked to different intrusive systems that developed in the retroarc region at different times, during the Jurassic, Cretaceous, Eocene, Miocene, and even the Quaternary which influenced the hydrocarbon system maturity. We analyzed the Moho structure through this retroarc region, as well as the crustal structure affected by different stages of regional extension. From continuous seismic noise data, we calculated the autocorrelograms to obtain the reflection response below each seismological station. This allowed imaging the surface of primary crustal reflectors and in a few stations the top of an asthenospheric anomaly (SWAP) found by magnetotelluric survey and in concordance with satellite magnetic data. The crustal reflectors were identified in all stations at a mean two-way travel time of about ∼8.5 s and ∼12.5 s using frequency bands of about 1.0–2.4 Hz. Therefore, this is the first geophysical research that estimates the depth of the magmatic system, hosted at the top of the lower crust and the Moho discontinuity. The deepest reflector, only recognized in 4 stations, was observed with a two-way travel time of 17.2 s to 19.6 s. We used a mean one-dimensional Vp model to obtain the corresponding reflector depths which constrain the two-dimensional forward gravity model that fits with the observed regional anomaly for the region. We finally established a relationship between the shallowest sublithospheric electrical conductivity anomalies determined in previous researches and the strong deep reflections observed in some of the seismological stations. This information may help to constrain geochemical and petrological models and re-evaluate the hydrocarbon system maturity of the northern Neuquén basin.

Study of Millimeter-Wave Fuze Echo Characteristics under Rainfall Conditions Using the Monte Carlo Method

Due to the similarity in wavelength between millimeter-wave (MMW) signals and raindrop diameters, rainfall induces significant attenuation and scattering effects that challenge the detection performance of MMW fuzes in rainy environments. To enhance the adaptability of frequency-modulated MMW fuzes in such conditions, the effects of rain on MMW signal attenuation and scattering are investigated. A mathematical model for the multipath echo signals of the fuze was developed. The Monte Carlo method was employed to simulate echo signals considering multiple scattering, and experimental validations were conducted. The results from simulations and experiments revealed that rainfall increases the bottom noise of the echo signal, with rain backscatter noise predominantly affecting the lower end of the echo signal spectrum. However, rain conditions below torrential levels did not significantly impact the detection of strong reflection targets at the high end of the spectrum. The modeling approach and findings presented offer theoretical support for designing MMW fuzes with improved environmental adaptability.

Raindrop Size Distribution Characteristics of the Precipitation Process of 2216 Typhoon “Noru” in the Xisha Region

This study focuses on the comparative analysis and research of the raindrop size distribution (DSD) in the outer rainband and inner rainband of Typhoon “Noru” in 2022, using the OTT-Parsivel raindrop spectrometer deployed on Yongxing Island, Sansha City. The results indicate that precipitation intensity is lower when composed mainly of small and medium raindrops and increases with the presence of larger raindrops. Stronger precipitation is associated with a higher number of large raindrops. Due to the interaction of cold and warm air masses, the raindrop concentration is higher, and the raindrop diameters are larger compared to Typhoons “LEKIMA” and “RUMBIA”. The entire process predominantly consists of numerous small- to medium-sized raindrops, characteristic of a tropical typhoon. The precipitation in the inner and outer rainbands exhibits consistent types, characterized by a unimodal raindrop size distribution with a narrow spectral width, typical of stratiform-mixed cloud precipitation, where stratiform precipitation constitutes a significant portion. Strong echo reflectivity factors are often associated with higher raindrop number concentrations and larger particle sizes. The Z-R relationship of the precipitation shows a smaller coefficient but a consistent exponent compared to the standard. The calculated shape parameter slope relationship is Λ=0.02μ2+0.696μ+1.539, providing a reference for localizing the Z-R relationship in the South China Sea.

Synthesis and characterization of novel yellow-green Cr, Zn-codoped Ba(Mg6Ti6)O19 pigments with high NIR reflectance

This work reports a series of yellow-green near-infrared (NIR) reflective pigments, Ba(Mg6-x-yZnyTi6-xCr2x)O19 (x = 0–1.0, y = 0–2.5), with strong NIR reflectivity for solar thermal energy regulation. Comprehensive analyses were carried out to characterize the obtained pigments including X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, UV–Vis–NIR spectrophotometry, and CIE L*a*b* color measurement. Absorption spectra of Ba(Mg6-xTi6-xCr2x)O19 showed that the yellow-green absorption is attributed to the octahedrally coordinated Cr3+ with d-d electron transitions of 4A2(F)→4T1(F) and 4A2(F)→4T2(F). However, their broad absorption peak centered at 1200 nm severely deteriorated the insulating properties of the pigments. Through substituting Mg with Zn, the obtained pigment Ba(Mg2.5Zn2.5Ti5Cr2)O19 showed an excellent NIR solar reflectance (R* = 67 %) with color performances (L* = 61.98, a* = −18.72, b* = 22.23). EnergyPlus simulation results show that for a warm city (Haikou), the Ba(Mg2.5Zn2.5Ti5Cr2)O19 coating for the external surface of a model house (TSR = 35 %, R* = 55 %) can reduce annual cooling energy consumption by 8 % of the house.

Optimizing MOF‐Derived Electromagnetic Wave Absorbers through Gradient Pore Regulation for Pareto Improvement

AbstractPorous materials emerging as potential high‐efficiency electromagnetic (EM) wave absorbers confront a critical trade‐off between impedance matching and attenuation capability. In this study, a versatile strategy is reported to overcome this challenge by constructing gradient pores via solvent‐assisted linker exchange for the fabrication of metal‐organic framework (MOF) derived Fe/Fe3Co7/Co/C composites with high porosity. The impedance and attenuation characteristics of single‐pored and gradient‐pored derivatives are investigated through combined experimental and simulation approaches. Simulated space EM field, loss density, and Smith charts reveal significantly enhanced EM interactions and optimized impedance within the pores. Compared to individual MOF derivatives, the gradient derivative exhibits improved impedance matching from the large‐pored shell and superior attenuation capability from the small‐pored core, giving rise to a Pareto improvement in EM absorption with strong reflection loss (−64.7 dB) and wide effective adsorption bandwidth (5.8 GHz) at a thickness of 2.5 mm. This work not only advances a novel gradient pore strategy for constructing efficient absorbers with enhanced impedance matching and attenuation capability, but also sheds light on the underlying mechanisms of EM interaction with varied porosity, offering insights for extended designs in magnetic, electric and optic devices.

Evidence for moth pollination in a rhinomyiophilous Erica species from the Cape Floristic Region of South Africa.

Contrasting pollination syndromes in closely related species suggest that floral trait divergence is associated with differences in pollination system, but empirical observations are required to confirm syndrome-based predictions. We present a comparative study of two closely related Erica species with contrasting pollination syndromes from the Cape Floristic Region of South Africa. Ericacylindrica has narrowly tubular pale and strongly scented flowers and is known to be hawkmoth-pollinated. The closely related Ericainfundibuliformis has bright flower colours and appears to lack scent, traits that are suggestive of pollination by long-tongued nemestrinid flies (rhinomyiophily). Floral trait measurements revealed that both species exhibit predominantly upright flower orientation and elongated floral tubes, although tube length of E.infundibuliformis is consistently greater than that of E.cylindrica. For both species, petals are brighter than floral tube surfaces, but flowers of E.cylindrica lack the strong UV reflectance found in E.infundibuliformis. Nectar of E.infundibuliformis is more concentrated and produced in larger volumes. Scent composition, but not evening scent emission rates, differed between the species: scent of E.cylindrica is dominated by aromatic compounds, whereas scent of E.infundibuliformis is dominated by (E)-ocimene and other terpenoid compounds and is emitted at higher rates during the day than the evening. Pollinator observations contradicted trait-based predictions: although a single nemestrinid fly captured in the vicinity of E.infundibuliformis did carry Erica pollen, almost all other diurnal flower visitors were nectar-robbing Hymenoptera which did not carry Erica pollen. Contrary to predictions, at two sites and over two flowering seasons, flowers were consistently visited in the evenings by several species of settling moths and hawkmoths which carried pollen, almost exclusively of Erica, on their proboscides. Our findings thus suggest that, despite objective differences in key floral traits between the closely related hawkmoth-pollinated E.cylindrica and E.infundibuliformis, moths are also important pollinators of E.infundibuliformis. A bimodal pollination system involving predominant pollination by moths and occasional visits by long-proboscid flies could partially reconcile findings with predictions. Our study further suggests that hawkmoth pollination may be more widespread in both Erica and the broader Cape flora than has hitherto been assumed and emphasises the importance of nocturnal pollinator observations.

Envelope normalized reflection waveform inversion

AbstractThe reflection waveform inversion has the capability to reconstruct the background velocity model using only the reflection data by employing a migration/demigration process. Utilizing the waveform discrepancy to update the background velocity model, the conventional reflection waveform inversion method heavily relies on the true‐amplitude migration/demigration technique to reproduce the primary amplitude information from the observed reflections. We can reproduce the amplitude of observed reflections by performing least‐squares reverse time migration to estimate the reflectivity in each iteration. However, this strategy is quite time‐consuming. To avoid the need for the true‐amplitude migration/demigration or least‐squares reverse time migration, we develop an amplitude‐independent reflection waveform inversion method that uses an envelope‐normalized objective function. The envelope‐normalized waveform difference can extract the phase residuals accurately as a function of time. Compared with the global energy–normalized misfit, our proposed envelope‐normalized objective function is essentially a phase‐matched measurement. At the same time, due to the amplitude independence of our proposed objective function, the subsequent weak reflections contribute with a similar weight to the total value of the misfit as the strong early reflections do. This makes it possible to recover the deep subsurface velocity. Synthetic data of the Sigsbee model and marine streamer field data applications validate that our amplitude‐independent reflection waveform inversion method can further improve the resolution and accuracy by aligning the reflection events of synthetic and observed data phase to phase without the need to perform true‐amplitude migration/demigration or least‐squares reverse time migration as in conventional reflection waveform inversion.

A new rhombohedral phase and its 48 variants in β titanium alloy

A new rhombohedral phase (termed R′) in a solution−aging-treated titanium alloy (Ti−4.5Al−6.5Mo−2Cr− 2Nb−1V−1Sn−1Zr, wt.%) was identified. Its accurate Bravais lattice parameters were determined by a novel unit cell reconstruction method based on conventional selected-area electron diffraction (SAED) technique. The orientation relationship between R′ phase and BCC phase was revealed. The results show that the R′ phase is found to have 48 crystallographically equivalent variants, resulting in rather complicated SAED patterns with high-order reflections. A series of in-situ SAED patterns were taken along both low- and high-index zone axes, and all weak and strong reflections arising from the 48 variants were properly explained and directly assigned with self-consistent Miller indices, confirming the presence of the rhombohedral phase. Additionally, some criteria were also proposed for evaluating the indexed results, which together with the Bravais lattice reconstruction method shed light on the microstructure characterization of even unknown phases in other alloys.

Self‐Standing Chiral Covalent Organic Framework Thin Films with Full‐Color Tunable Guest‐Induced Circularly Polarized Luminescence

Exploring self‐standing chiral covalent organic framework (CCOF) thin films with controllable circularly polarized luminescence (CPL) is of paramount significance but remains challenging. Herein, we demonstrate the first example of self‐standing CCOF films employing a polymerization‐dispersion‐filtration strategy. Pristine, low‐quality CCOF films were produced by interfacial polymerization and then re‐dispersed into COF colloidal solutions. Via vacuum assisted assembly, these COF colloids were densely stacked and assembled into self‐standing, pure chiral COF films (L‐/D‐CCOF‐F) that were transparent, smooth, crack‐free and highly crystalline. These films were tunable in thicknesses, areas, and roughness, along with strong diffuse reflectance circular dichroism (DRCD) and cyan CPL signals, showing an intrinsic luminescence asymmetric factor (glum) of 4.3×10‐3. Furthermore, these COF films served as host adsorbents to load various achiral organic dye guests through adsorption. The effective chiral transfer and energy transfer between CCOF‐F and achiral fluorescent dyes endowed the dyes with strong chirality and tunable DRCD, resulting in intense, full‐color‐tunable solid‐state CPL. Notably, the ordered arrangement of dye guest molecules within the preferentially oriented chiral pores of CCOF‐F contributed to an amplified |glum| factor of 7.2×10‐2, which is state‐of‐the‐art for COF‐based CPL materials. This work provides new insights into the design and fabrication of self‐standing chiral COF films.

Lithofacies identification of deep coalbed methane reservoir based on high-resolution seismic inversion

During the exploration and development of deep coalbed methane (CBM), delineating the thickness of coal seam and lithofacies of the roof and floor is one of the major challenging tasks. In past attempts, the prediction methods of these parameters have been limited to the conventional inversion. However, the effect of coal shielding on adjacent reflecting layers restricts the identification of underlying sand effectively by conventional inversion. Also, the depth at which the deep CBM zone is located (1,500–2000 m) produces a significant overlap of P-wave impedance and Vp/Vs of sands and shale which increases classification uncertainty between these two lithofacies. We proposed a new workflow for high-precision quantitative seismic interpretation of deep CBM reservoir. Not only P-wave impedance but also GR is selected as the optimized attributes for lithofacies classification. To reduce the effect of strong reflection of coal seam and identifying thin coal layers, the seismic waveform indication inversion method is used to obtain high-resolution results of P-wave impedance and GR. It uses horizontal changes in seismic waveforms to reflect lithological assemblage characteristics for facies-controlled constraints. Then, Bayesian classification theory is used to achieve three-dimensional lithofacies classification with multi-source data. To improve the continuity and accuracy of the interpreted results, a Markov chain is applied in the Bayesian rule as the spatial prior constraint. A well-associated synthetic test and field data application in Ordos Basin demonstrates the accuracy of the proposed workflow. Compared with conventional inversion, the results of proposed workflow showed higher resolution and accuracy. By providing a new solution for the identification of roof and floor lithofacies of deep CBM reservoir, this workflow aims to contribute to the better exploration and development of deep CBM.