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Abstract Background Small-cell lung cancer (SCLC) is a leading cause of cancer-related death. However, the prognostic value of the tumor shrinkage rate (TSR) after chemotherapy for SCLC is still unknown. Methods We performed a retrospective analysis of 235 patients with SCLC. The TSR cutoff was determined based on receiver-operating characteristic curve analysis. The associations of TSR with progression-free survival (PFS) and overall survival (OS) were assessed using univariate and multivariate Cox proportional hazards models. Survival curves were obtained by the Kaplan–Meier method and compared using the log-rank test. Recurrence patterns after first-line treatment were summarized in a pie chart. A nomogram was constructed to validate the predictive role of the TSR in SCLC. Results The TSR cutoff was identified to be − 6.6%. Median PFS and OS were longer in the group with a TSR − 6.6%. Brain metastasis-free survival was better in the group with a TSR

IntroductionOxidative stress has been identified as a major contributor to the pathogenesis of DR, and many diagnostic and therapeutic strategies have been developed to target oxidative stress. Our aim was to understand the contribution of the country of origin of the publication, the institution, the authors, and the collaborative relationship between them.MethodsWe performed a bibliometric analysis to summarize and explore the research hotspots and trends of oxidative stress in the DR.ResultsWe observe an upward trend in the number of posts on related topics from year to year. Expanding on this, Queens University Belfast is the most influential research institution. Current research hotspots and trends focus on the mechanism of autophagy and NLRP3 inflammasome's role in oxidative stress in DR.DiscussionWe conducted a multi-dimensional analysis of the research status of oxidative stress in diabetic retinopathy through bibliometric analysis, and proposed possible future research trends and hotspots.

BackgroundThrough preoperative localization, surgeons can easily locate ground glass nodules (GGNs) and effectively control the extent of resection. Therefore, it is necessary to choose an appropriate puncture positioning method. The purpose of this study was to evaluate the effectiveness and safety of medical glue and positioning hooks in the preoperative positioning of GGNs and to provide a reference for clinical selection.MethodsFrom March 30, 2020 to June 13, 2022, a total of 859 patients with a CT diagnosis of GGNs requiring surgical resection were included in our study at the hospital. Among them, 21 patients who either opted out or could not undergo preoperative localization for various reasons were excluded. Additionally, 475 patients who underwent preoperative localization using medical glue and 363 patients who underwent preoperative localization through positioning hooks were also excluded. We conducted statistical analyses on the baseline data, success rates, complications, and pathological results of the remaining patients. The success rates, complication rates, and pathological results were compared between the two groups—those who received medical glue localization and those who received positioning hook localization.ResultsThere was no statistically significant difference between the two groups of patients in terms of age, body mass index, smoking history, location of the nodule, distance of the nodule from the pleura, or postoperative pathological results (P > 0.05). The success rate of medical glue and positioning hooks was 100%. The complication rates of medical glue and positioning hooks during single nodule positioning were 39.18% and 23.18%, respectively, which were significantly different (p < 0.001); the complication rates during multiple nodule positioning were 49.15% and 49.18%, respectively, with no statistically significant differences (p > 0.05). In addition, the method of positioning and the clinical characteristics of the patients were not found to be independent risk factors for the occurrence of complications. The detection rate of pulmonary nodules also showed some positive correlation with the spread of COVID-19 during the 2020–2022 period when COVID-19 was prevalent.ConclusionWhen positioning a single node, the safety of positioning hooks is greater than when positioning multiple nodes, the safety of medical glue and positioning hooks is comparable, and the appropriate positioning method should be chosen according to the individual situation of the patient.

ABSTRACT: The rise of operational noise as an environmental pollutant for farm animals is an emerging concern. The mechanisms through which music can alleviate oxidative stress, inflammation, and apoptosis induced by noise exposure remain underexplored. This study aims to investigate the alleviating effects and underlying mechanisms of long-term music exposure on noise-induced damage to the chicken spleen. Male Arbor Acres (AA) broilers were divided into four groups: control (C), acute noise stimulation (NS), noise stimulation with music mitigation (NSM), and music only (M). NS and NSM groups were exposed to noise (simulating sudden intensity noise, 115 to 120dB) for 10 minutes daily for a week, starting at 14-days-old. NSM and M groups then received 28 days of 6-hour daily music (Mozart K.448, 60–65 dB). The results showed that noise stimulation significantly activated the Keap-1/Nrf2 and NF-κB signaling pathways. Long-term music intervention has also been demonstrated to successfully mitigate oxidative stress and abnormal apoptosis induced by acute noise stimulation. Microscopic examination of the spleen revealed that acute noise stimulation resulted in an increase in splenic cells, a decrease in lymphocytes, and blurred boundaries between the red and white pulps in the NS group. However, these pathological changes were alleviated in the NSM group following music intervention. Compared with the control group, the NS group exhibited significantly elevated oxidative stress parameters. In contrast, music intervention in the NSM group notably improved antioxidant capacity and partially alleviated morphological abnormalities in the spleen. Additionally, noise stimulation activated the NF-κB pathway, upregulating the downstream genes of the inflammatory factors IL-1β, IL-6, and TNF-α. Noise-induced mitochondrial damage led to apoptosis, as observed by TUNEL staining, along with increased gene and protein expression of Bcl-2, Bax, Cyt-C, Casp-3, Casp-8, and Casp-9. These findings indicate that acute noise exposure can induce splenic damage via oxidative stress, inflammation, and apoptosis by modulating the Keap-1/Nrf2 and NF-κB pathways. Prolonged music stimulation effectively mitigates noise-induced damage, offering a vital experimental foundation for further research on noise pollution's impact on organisms and music's alleviating role.

ABSTRACT: The aim of this study was to investigate the effects of prolonged exposure to varying levels of music or noise on the behavioral, physiological, and immune responses of pullets following their transfer to an egg-laying facility. A total of 240 one-day-old Hy-Line Brown pullets were randomly assigned to five groups: 0 dB sound stimulation, low-decibel music (65–75 dB), high-decibel music (85–95 dB), low-decibel noise (65–75 dB), and high-decibel noise (85–95 dB) stimuli. Pullets received music or noise stimuli 10 h per d from 1-day-old to 16-wk-old and were then transferred to the egg-laying facility. The results indicated that feeding and drinking behaviors significantly decreased (P < 0.05), whereas feather pecking, aggression, and preening behaviors significantly increased (P < 0.05) in the pullets after transfer. Pullets also had higher serum cortisol (COR) levels (P < 0.05), whereas immunoglobulin Y (IgY), tumor necrosis factor-α (TNF-α), interferon-γ (INF-γ), interleukin-1β (IL-1β), interleukin-2 (IL-2) and interleukin-6 (IL-6) levels significantly increased (P < 0.05). Low-decibel sound stimuli increased aggressive behavior and decreased pecking behavior (P < 0.05). High-decibel sound stimuli decreased feather pecking, cage pecking, aggression, and sham dustbathing behaviors (P < 0.05). In addition, a low-decibel sound stimulus decreased the serum COR content, and increased the serum IL-6 level in the transferred pullets. A high-decibel sound stimulus also induced shorter tonic immobility (TI) durations in pullets on d 7 after transport stress. Meanwhile, high-decibel sound stimulus decreased the serum IL-6 and TNF-α levels of pullets. In conclusion, the transfer has detrimental effects on the pullets. Long-term sound stimulation effectively mitigated the negative impact of transportation stress on pullets. Among them, the high-decibel sound stimulus showed more promise in relieving transport stress.

In marine environments, viruses play a pivotal role, yet deep-sea bacteriophages remains largely uncharacterized. The bacterium Labrenzia aggregata RF14, isolated from the Mariana Trench at a depth of 4,000 meters, harbors prophage regions based on a previous study. In this study, we induced a temperate bacteriophage from it using mitomycin C. The bacteriophage exhibited an icosahedral structure with a non-extendable tail and was named vB_LagS-V1. The genome size of it is 39,329 bps with a 59.46% G+C content, encoding 60 putative open reading frames. Genomic and phylogenetic analyses demonstrated that vB_LagS-V1 along with many bacteriophages infecting Hyphomicrobiales, constituted a newly unclassified family, which we designated as Hyphoviridae. Within this novel family, vB_LagS-V1 is distinct with isolated phages and clustered with two uncultured prophages within Labrenzia, forming an unclassified new genus, given a name of Labrenmarinevirus. The codon usage correlation and absence of tRNAs found in vB_LagS-V1, also prevail in some deep-sea bacteriophages, highlighting their adaptations to the deep-sea prokaryotic hosts. Moreover, vB_LagS-V1 encoded two auxiliary metabolic genes, cysteine dioxygenase and phosphoadenosine phosphosulfate reductase, which might help the phage and its host adapt to high hydrostatic pressure in the deep-sea environments. Our study will significantly contribute to the understanding of deep-sea bacteriophages and their interactions with hosts in extreme environments.

As an environmental enrichment, music can positively influence the immune function, while noise has an adverse effect on the physical and mental health of humans and animals. However, whether music-enriched environments mitigate noise-induced acute stress remains unclear. To investigate the anti-inflammatory effects of music on the immune organs of broiler chickens under conditions of early-life acute noise stress, 140 one-day-old white feather broilers (AA) were randomly divided into four groups: control (C), the music stimulation (M) group, the acute noise stimulation (N) group, the acute noise stimulation followed by music (NM) group. At 14 days of age, the N and NM groups received 120 dB noise stimulation for 10 min for one week. After acute noise stimulation, the NM group and M group were subjected to continuous music stimulation for 14 days (6 h per day, 60 dB). At 28 days of age, the body temperature of the chicks, the histopathological changes, quantification of ROS-positive density and apoptosis positivity in tissues of spleen, thymus, and bursa of Fabricius (BF) were measured. The results showed that acute noise stimulation led to an increase in the number and area of splenic microsomes and the cortex/medulla ratio of the detected immune organs. The activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) of immune tissues of broilers in N group were decreased compared to the broilers in C group, while the mRNA levels of malondialdehyde (MDA), TNF-α, IL-1, and IL-1β increased. In addition, the gene and protein expression levels of IKK, NF-κB, and IFN-γ of three immune organs from broilers in the N group were increased. Compared to the C and N group, chickens from the NM group showed a decrease in the number and area of splenic follicles, an increase in the activities of SOD and GSH-Px, and a decrease in the expression levels of MDA, TNF-α, IL-1, and IL-1β. Therefore, a music-enriched environment can attenuate oxidative stress induced by acute noise stimulation, inhibiting the activation of the NF-κB signaling pathway and consequently alleviating the inflammatory response in immune organs.

ABSTRACT Through particles sinking as well as the movement of water masses, a fraction of bacterioplankton and virioplankton can be transported vertically from the surface to the deep oceans, and display significant changes in viral–bacterial interactions. The survival and activity of the sinking prokaryotes and viruses in the deep-sea environment is crucial for our understanding of deep-sea ecosystems and biogeochemical cycles. However, due to the substantial challenge involved in situ deep-sea incubation, the effect of the deep-sea environments on the ecology of surface prokaryotes and viruses is poorly studied. To fill this knowledge gap, we used an in situ deep-sea long-term incubation device to examine the effect of the natural deep-sea environment on the stability and activity of four viruses and their hosts (Prochlorococcus, Synechococcus, and heterotrophic bacteria) isolated from the surface ocean. Our results showed that viral particles had still not decayed completely after in situ incubation for 1 year, with an average retention rate of 5.69% ± 5.13% (ranging from 1.25% to 13.06%) for infectivity and 68.11% ± 40.50% (ranging from 8.55% to 99.08%) for particles. This suggests that surface viruses probably retain long-term infectivity after sinking and may influence deep-sea microbial populations in terms of activity, function, diversity, and community structure through viral–bacterial interactions and ultimately affect deep-sea biogeochemical cycles. IMPORTANCE The survival of the sinking prokaryotes and viruses in the deep-sea environment is crucial for deep-sea ecosystems and biogeochemical cycles. Through an in situ deep-sea long-term incubation device, our results showed that viral particles and infectivity had still not decayed completely after in situ incubation for 1 year. This suggests that, via infection and lysis, surface viruses with long-term infectious activity in situ deep-sea environments may influence deep-sea microbial populations in terms of activity, function, diversity, and community structure and ultimately affect deep-sea biogeochemical cycles, highlighting the need for additional research in this area.

Forest fires require rapid and precise early smoke detection to minimize damage. This study focuses on employing smoke recognition methods for early warning systems in forest fire detection, identifying smoke as the primary indicator. A significant hurdle lies in the absence of a large-scale dataset for real-world early forest fire smoke detection. Early smoke videos present characteristics such as smoke plumes being small, slow-moving, and/or semi-transparent in color, and include images where there is background interference, posing critical challenges for practical recognition algorithms. To address these issues, this paper introduces a real-world early smoke monitoring video dataset as a foundational resource. The proposed 4D attention-based motion target enhancement network includes an important frame sorting module which adaptively selects essential frame sequences to improve the detection of slow-moving smoke targets. Additionally, a 4D attention-based motion target enhancement module is introduced to mitigate interference from smoke-like objects and enhance recognition of light smoke during the initial stages. Moreover, a high-resolution multi-scale fusion module is presented, incorporating a small target recognition layer to enhance the network’s ability to detect small smoke targets. This research represents a significant advancement in early smoke detection for forest fire surveillance, with practical implications for enhancing fire management.

This study centers on leveraging smoke detection for preemptive forest smoke detection. Owing to the inherent ambiguity and uncertainty in smoke characteristics, existing smoke detection algorithms suffer from reduced detection accuracy, elevated false alarm rates, and occurrences of omissions. To resolve these issues, this paper employs an efficient YOLOv8 network and integrates three novel detection modules for enhancement. These modules comprise the edge feature enhancement module, designed to identify smoke ambiguity features, alongside the multi-feature extraction module and the global feature enhancement module, targeting the detection of smoke uncertainty features. These modifications improve the accuracy of smoke area identification while notably lowering the rate of false alarms and omission phenomenon occurrences. Meanwhile, a large forest smoke dataset is created in this paper, which includes not only smoke images with normal forest backgrounds but also a considerable quantity of smoke images with complex backgrounds to enhance the algorithm’s robustness. The proposed algorithm in this paper achieves an AP of 79.1%, 79.2%, and 93.8% for the self-made dataset, XJTU-RS, and USTC-RF, respectively. These results surpass those obtained by the current state-of-the-art target detection-based and neural network-based improved smoke detection algorithms.

The hot deformation behavior of titanium matrix composites plays a crucial role in determining the performance of the formed components. Therefore, it is significant to establish an accurate constitutive relationship between material deformation parameters and flow stress. In this study, hot compression experiments were conducted on a (2.5 vol%TiB + 2.5 vol%TiC)/TC4. The experiments were performed under temperatures ranging from 1013.15 to 1133.15 K and strain rates ranging from 0.001 to 0.1 s−1. Based on the stress–strain data obtained from the experiment, the constitutive models were established by using the Arrhenius model and the BP neural network algorithm, respectively. Considering the relationship between strain rate, hot working temperature, and flow stress, a comparative analysis was conducted to evaluate the prediction accuracy of two different constitutive models. The research results indicate that the flow stress of (2.5 vol%TiB + 2.5 vol%TiC)/TC4 increases with decreasing temperature and increasing strain rate, and the stress–strain curve shows obvious work hardening and softening behaviors. Both the Arrhenius model and the BP neural network algorithm are effective in predicting the hot compression flow stress of (2.5 vol%TiB + 2.5 vol%TiC)/TC4, but the average relative error and root mean square error of the BP neural network algorithm are smaller and the correlation coefficient is higher, thus possessing higher accuracy and reliability.

Abstract Boson quantum error correction is an important means to realize quantum error correction information processing. In this paper, we consider the connection of a single-mode Gottesman-Kitaev-Preskill (GKP) code with a two-dimensional (2D) surface (surface-GKP code) on a triangular quadrilateral lattice. On the one hand, we use a Steane-type scheme with maximum likelihood estimation for surface-GKP code error correction. On the other hand, the minimum-weight perfect matching (MWPM) algorithm is used to decode surface-GKP codes. In the case where only the data GKP qubits are noisy, the threshold reaches σ ≈ 0.5 ( $$\bar{p}\approx 12.3 \%$$ p ¯ ≈ 12.3 % ). If the measurement is also noisy, the threshold is reached σ ≈ 0.25 ( $$\bar{p}\approx 10.02 \%$$ p ¯ ≈ 10.02 % ). More importantly, we introduce a neural network decoder. When the measurements in GKP error correction are noise-free, the threshold reaches σ ≈ 0.78 ( $$\bar{p}\approx 15.12 \%$$ p ¯ ≈ 15.12 % ). The threshold reaches σ ≈ 0.34 ( $$\bar{p}\approx 11.37 \%$$ p ¯ ≈ 11.37 % ) when all measurements are noisy. Through the above optimization method, multi-party quantum error correction will achieve a better guarantee effect in fault-tolerant quantum computing.

The wastewater generated from monosodium glutamate production displays distinctive features of elevated salinity, organic content, as well as nitrogen and phosphorus concentrations, and its indiscriminate disposal poses a significant threat to water quality and can cause detrimental impacts on aquatic ecosystems. The application of microalgae for monosodium glutamate wastewater (MSGW) treatment can result in simultaneous wastewater purification and biomass recovery. In this study, the algae species capable of thriving in diluted MSGW were screened, and the wastewater composition and growth conditions were optimized to obtain high algal biomass and nutrient removal rate. Among the tested species, Chlorella sp. FACHB-30 demonstrated superior potential for MSGW treatment and achieved a maximum specific growth rate of 0.28 d−1 and the highest COD removal rate of 61.50% over a 20-day cultivation period with trace metals supplementation in the wastewater. Moreover, the cultivation of Chlorella sp. FACHB-30 yielded considerable reductions in total phosphate (69.09%), total nitrogen (26.93%), and NH4+-N (51.91%) levels in the wastewater. The optimum conditions for achieving maximum algal density and highest nutrient removal were determined as light intensity of 150 μmol m−2s−1, inoculation concentration of 1 × 105 cells mL−1, and an iron concentration of 10−5 mol L−1. Finally, under the optimized conditions, the removal rates of total phosphate, total nitrogen, NH4+-N, and COD were determined to be 87.60%, 68.05%, 75.89%, and 77.96%, respectively. The findings of this study highlight the potential for enhancing the nutrient removal efficiency of microalgae-based MSGW treatment through the implementation of a combined approach that involves the selection of tolerant strains, optimization of cultivation conditions, and refinement of wastewater composition.

Iron is a limiting factor that controls the phytoplankton biomass of the ocean and plays an important role in the lipid production of microalgae. Elucidating the effects of different iron valences on microalgae is helpful for their commercial production. We investigated the growth, photosynthesis, and fatty acid profile of the model diatom Phaeodactylum tricornutum cultured with depleted Fe, Fe2+, Fe2+/Fe3+, and Fe3+. Samples were taken every 24 h for 8 days, and their cell density, photosynthetic pigment content, chlorophyll fluorescence, total fatty acid content, and fatty acid composition were analyzed. The cell densities of the Fe2+ and Fe2+/Fe3+ groups were significantly higher than those of the control and Fe3+ groups (p < 0.05). They were 1.26 times and 1.23 times higher than those in the Fe-depleted group. The contents of chlorophyll a and c in the Fe2+ group were significantly higher than those in the Fe-depleted group (p < 0.05). The chlorophyll fluorescence results show that Fe2+ enhanced the photosynthesis of P. tricornutum to a greater extent than Fe3+. On the eighth day of harvest, Fv/Fm and Y(II) in the Fe2+ group were 0.672 and 0.476, respectively, being 1.10 and 1.19 times greater than those in the Fe3+ group and 1.15 and 1.33 times greater than those in the Fe-depleted group, respectively. Compared with the control group, the levels of saturated fatty acids of the Fe2+/Fe3+ and Fe3+ groups were significantly higher (p < 0.05) at 21.36 ± 1.24% and 21.20 ± 0.13%, respectively. The levels of polyunsaturated fatty acids of the Fe2+/Fe3+ group were significantly lower (p < 0.05) at 29.82 ± 2.75%. Our results show that P. tricornutum exhibited physiological plasticity, including changes in photosynthetic activities and shifts in fatty acid composition, in response to different iron valences and that Fe2+ was more beneficial to the biomass production of this species than Fe3+. These findings are applicable to the production of biomass and polyunsaturated fatty acids.

Oxepinamides are a class of fungal oxepins with biological activities. Here, the authors elucidate the biosynthetic pathway of oxepinamide F from Aspergillus ustus and show that it involves enyme-catalysed oxepin ring formation, hydroxylation-induced double bond migration, epimerization and methylation.

Abstract Background There has been little published data on estimates of HBV and/or HCV coinfection in HIV-positive patients in China or an understanding of how this coinfection varies with different factors. Therefore, this study aimed to determine, through a systematic review and meta-analysis, the prevalence of HBV and/or HCV in HIV-positive patients in China and explore variations in prevalence. Methods The Medicine, Web of Science, Chinese Web of Knowledge, and Wanfang databases were searched using a search strategy combining key words and related disease-specific subject terms to identify relevant cohort or cross-sectional studies published up to April 2019. Included articles were assessed for quality. Pooled prevalence and 95% confidence intervals (CIs) were calculated according to study region and other specific characteristics. Results Our searches identified 7843 records, but only 66 studies were included in our meta-analysis. The pooled HBsAg prevalence in HIV-positive patients was 13.7% (95% CI 12.3–15.3%), with variations found in terms of age and geographic region. The meta-HCV prevalence was 24.7% (95% CI 19.3–30.5%), which varied over the study period and age. The pooled HBV-HCV coinfection prevalence was 3.5% (95% CI 2.4–4.8%), with variations found in terms of age and geographic region. Conclusion Given the high burden of HBV and HCV coinfections in HIV-positive patients, the incorporation of comprehensive screening, treatment, prevention, and vaccination programs into general HIV management in China is imperative.

As industrial development increases, electric machine systems are more widely used in industrial production. Rolling bearings play a key role in machine systems and so the prevention of faults in rolling bearings is more important than ever before. Recently, with the development of artificial intelligence, neural networks have been used to monitor the remaining useful life of rolling bearings. However, there are two problems with this technique. First, a network trained by data for a single operating condition (source domain) cannot predict the remaining useful life of bearings under a different operating condition (target domain), such as a different load or speed. Second, a large number of labeled data are needed for network training, but the acquisition of labeled data for different operating conditions is a challenging task. To address these problems, this paper proposes a domain-adaptive adversarial network, in which a transfer learning strategy and maximum mean discrepancy algorithm are used for network optimization, so that remaining useful life can be predicted without labeled data in target domain training. Our results confirm that a model trained by source domain data alone cannot predict the remaining useful life of bearings under different conditions, but the domain-adaptive adversarial network can accurately predict remaining useful life for varying operating conditions. The method proposed also exhibits good performance even if there are noises in the signals.

The determination of the antiferromagnetic (AFM) orders by the anisotropic magnetoresistance (AMR) is one of the key components to the AFM-spintronics. Here the authors report enhanced AMR ~160% in Sr2IrO4 due to the combination of atomic scale giant-MR-like effect and magnetocrystalline anisotropy energy.

This paper presents a measurement-based analysis of wideband 39 GHz millimeter wave (mm-wave) dual-polarized propagation channel under the impact of foliage presence between a transmitter (Tx) and a receiver (Rx). The measurements were conducted in a rich-vegetation area, and the so-called direction-scan-sounding (DSS) method which rotates a horn antenna in angular domains was applied, aiming at investigating the direction-of-arrival (DoA)-dependent characteristics of polarimetric channels. Four Tx-to-Rx polarization configurations were considered, including co-polarization scenarios with vertical Tx-polarization to vertical Rx-polarization (VV) and horizontal to horizontal (HH), as well as cross-polarization with vertical to horizontal (VH) and horizontal to vertical (HV), which allow scrutinizing the differences in delay-direction dispersion for usually-encountered scenarios. A foliage loss model for various vegetation depths in VV polarization configuration, was also presented in this paper. The results show that the foliage-loss DoA spectra for VH and HV are similar, while the spectra exhibit less penetration loss in most directions for VV than for the HH. Furthermore, the presence of vegetation between the Tx and the Rx leads to larger dispersion in delay compared to the clear line-of-sight (LoS) scenario, particularly for vertical polarization in the Tx side, and additionally, the foliage presence also results in evident DoA dispersion, specially in the HV scenario. Selectivity in directions caused by foliage is more significant in vertically-polarized Tx scenarios than in the horizontally-polarized Tx scenarios. A statistical model is established summarizing these comparison details.

This paper introduces a measurement campaign to investigate the characteristics of massive multiple-input multiple-output (MIMO) channels in both line-of-sight (LoS) and obstructed LoS suburban outdoor environments. The measurements are conducted at the center frequency of 3.5 GHz with a bandwidth of 160 MHz. The transmitter is equipped with a 4 × 8 planar patch antenna array and the receiver is equipped with a 4 × 8 cylindrical patch antenna array. Each patch consists of two antenna ports which have main polarizations of +45° and -45°, respectively, resulting in a total of 64 × 64 sub-channels. We examined the influence of different polarization combinations on channel characteristics such as power delay profile (PDP), K-factor and delay spread for both LoS and obstructed LoS scenarios. Results show that the characteristics are more dependent on the Rx antennas rather than the Tx antennas. When the Rx antennas are facing the Tx antenna array, the received power is higher, the K-factor is lower and the delay spread is lower in cross-polarization cases with respect to the co-polarization ones in general. When the Rx antennas are back-facing the Tx antenna array, lower powers, higher K-factors and higher delay spreads can be observed in cross-polarization cases with respect to the co-polarization cases. In conclusion, the polarimetric influence on the channel characteristics depends on the antenna structure as well as the environment.

The pulsed eddy current (PEC) inspection is considered a versatile non-destructive evaluation technique, and it is widely used in metal thickness quantifications for structural health monitoring and target recognition. However, for non-ferromagnetic conductors covered with non-uniform thick insulating layers, there are still deficiencies in the current schemes. The main purpose of this study is to find an effective feature, to measure wall thinning under the large lift-off variations, and further expand application of the PEC technology. Therefore, a novel method named the dynamic apparent time constant (D-ATC) is proposed based on the coil-coupling model. It associates the dynamic behavior of the induced eddy current with the geometric dimensions of the non-ferromagnetic metallic component by the time and amplitude features of the D-ATC curve. Numeral calculations and experiments show that the time signature is immune to large lift-off variations.

Helicopter autorotation trajectory planning problems have been dealt within computationally expensive optimal control algorithms. This paper presents an efficient helicopter autorotation trajectory planning method, using functional tensor-train- (FT-) based dynamic programming (DP) algorithms. The autorotation trajectory planning method is shown real-time feasible, which involves general helicopter autorotation dynamics at the same time. To validate the dynamic feasibility of the trajectories, a trajectory-tracking controller using active disturbance rejection control (ADRC) is designed to ensure a helicopter model tracks the trajectories. Finally, a helicopter autorotation simulation with a six-degree-of-freedom high-fidelity multibody-based helicopter model is demonstrated for validation.

Boiling, the most frequent edible way to hotpot seasoning (HS), exerts a significant impact on the aroma of HS. The present study employed, for the first time, a novel switchable system between GC-O-MS and GC×GC-O-MS (SGC/GC×GC-O-MS) to study the aroma compounds of HS and hotpot seasoning boiling liquid (HSBL). A total of 79 aroma compounds and 56 aroma-active compounds were identified. The aroma extract dilution analysis (AEDA) was used to analyze the differences between the key aroma-active components in the HS and HSBL. The results showed that 13 aroma-active components were significantly affected by boiling, such as D-limonene, methional, and linalool. Moreover, a total of 22 key aroma-active components were identified through the odor activity values (OAVs) calculation. Of them, (E)-2-octenal (fatty) and linalool showed a significant difference, suggesting them to be the most critical aroma-active compounds in the HSBL, and HS, respectively. Finally, the correlation between key aroma-active compounds and the sensory properties of HS and HSBL was studied. These results demonstrated that the OAVs of key aroma-active compounds could characterize the real information of samples through bidirectional orthogonal partial least squares (O2PLS). The analysis results were consistent with the sensory evaluation results.

The aerodynamic performance of a reduced-scale coaxial rigid rotor system in hover and steady forward flights was experimentally investigated to gain insights into the effect of interference between upper and lower rotors and the influences of the advance ratio, shaft tilt angle and lift offset. The rotor system featured by 2 m-diameter, four-bladed upper and lower hingeless rotors and was installed in a coaxial rotor test rig. Experiments were conducted in the Φ3.2 m wind tunnel at China Aerodynamics Research and Development Center (CARDC). The rotor system was tested in hover states at collective pitches ranging from 0° to 13° and it was also tested in forward flights at advance ratios up to 0.6, with specific focus on the shaft tilt angle and lift offset sweeps. To ensure that the coaxial rotor was operating in a similar manner to that of the real flight, the torque difference was trimmed to zero in hover flight, whilst the constant lift coefficient was maintained in forward flight. An isolated single-rotor configuration test was also conducted with the same pitch angle setting in the coaxial rotor. The hover test results demonstrate that the figure of merit (FM) value of the lower rotor is lower than that of the upper rotor, and both are lower than that of the isolated single rotor. Moreover, the coaxial rotor configuration can contribute to better hover efficiency under the same blade loading coefficient (CT/σ). In forward flight, the effective lift-to-drag (L/De) ratio of the coaxial rigid rotor does not monotonously change as the advance ratio increases. Increases in the required power and drag in the case with a high advance ratio of 0.6 leads to the decreasing L/De ratio of the rotor. Meanwhile, the L/De ratio of the rotor is relatively high when the rotor shaft is tilted backward. The increasing lift offset tends to result in reduced required rotor power and an increase in the rotor drag. When the effect of the reduced rotor power is greater than that of the increased rotor drag, the L/De ratio increases as the lift offset increases. The L/De ratio can benefit significantly from lift offset at a high advance ratio, but it is much less influenced by lift offset at a low advance ratio. The forward performance efficiency of the upper rotor is poorer than that of the lower rotor, which is significantly different from the case in the hover flight.

In this paper, the performances of a space-alternating generalized expectation-maximization (SAGE) algorithm and a MUltiple Signal Identification Classification (MUSIC) technique are compared when they are used to estimate the parameters of multipath components in a propagation channel from measurement data acquired by stepping a horn antenna in directions. The impacts of the horn antenna's half-power beamwidth (HPBW) and the stepping strategy on root mean squared estimation error and the intrinsic resolution of the estimators are investigated through simulations. The results demonstrate that the performances of both methods rely on the settings of the direction-scan strategy and the antenna HPBW. In general, the MUSIC algorithm, which owns a superior resolution, is less sensitive to the scan configuration and more suitable for scenarios of high signal-to-noise power ratio compared with the SAGE algorithm. Measurement data collected at 13-17 GHz is processed by using both algorithms. The results show that the MUSIC technique can be used to provide similar results with those of the SAGE algorithm at a time consumption significantly reduced.

Main rotor actuator failure leads to catastrophic accidents for single main rotor helicopters. This paper focuses on safe landing trajectories after an actuator is locked in place by the remaining actuators, without introducing other control inputs. A general swashplate geometry is described, and new reconfiguration solutions for the control mixer are presented. The safe landing trajectories are obtained by formulating a nonlinear optimal control problem based on a nonlinear helicopter dynamic model and geometry constraints due to actuator failure. Safe landing trajectory results are shown with various initial forward velocities of all actuator failure cases. The safe initial speed boundaries are also explored by employing speed sweeps.

As an electromagnetic field conversion tool in the transient electromagnetic method (TEM), the weak coupling coils reduce the mutual inductance of its transmitter and receiver coils by special structural optimization, so the detection signal can be protruded from the primary field interference generated by the transmitter coil; thus, this kind of coil design can significantly improve the signal-to-noise ratio. However, with the popularity of drag or aerial TEM exploration, the structural stability problem caused by bumps or windage leads to non-negligible primary field leakages, thereby reducing the detection reliability. This paper incorporates the primary field shielding stability as a key indicator of the weak coupling designs and proposes a calibration scheme for this stability assessment, based on which the shielding stability of five typical weak coupling coil designs is quantitatively compared, and the relationship between the primary field density and the shielding stability explored in this study may contribute to the selection and improvement of TEM coils.

The multi-coil sensor consisting of a series of sub-coils provides a reliable way to avoid signal distortion from excitation field. Compared with conventional coil sensors, the multi-coil sensor exhibits more complex signal conversion performance, and the conventional equivalent circuit cannot reveal the possible attenuated oscillation, which seriously degrades the detection reliability. Based on a novel equivalent circuit model, this research investigates the causes of signal oscillation and proposes and validates an effective solution, which contributes to the signal transmission characteristics of multi-coil sensors for engineering applications.

The tunnel seismic method allows for the detection of the geology in front of a tunnel face for the safety of tunnel construction. Conventional geophones have problems such as a narrow spectral width, low sensitivity, and poor coupling with the tunnel wall. To tackle issues above, we propose a semi-automatic coupling geophone equipped with a piezoelectric sensor with a spectral range of 10−5000 Hz and a sensitivity of 2.8 V/g. After the geophone was manually pushed into the borehole, it automatically coupled with the tunnel wall under the pressure of the springs within the device. A comparative experiment showed that the data spectrum acquired by the semi-automatic coupling geophone was much higher than that of the conventional geophone equipped with the same piezoelectric sensor. The seismic data were processed in combination with forward modeling. The imaging results also show that the data acquired by the semi-automatic coupling geophone were more in line with the actual geological conditions. In addition, the semi-automatic coupling geophone’s installation requires a lower amount of time and cost. In summary, the semi-automatic coupling geophone is able to efficiently acquire seismic data with high fidelity, which can provide a reference for tunnel construction safety.