•High sensitivity volatile organic compounds (VOCs) sensors based on a tapered small core single mode fiber (TSCSMF) and a microfiber coupler (MFC) are reported.•Silica based materials containing ...immobilized Nile red prepared by sol-gel method with two different recipes (recipe I and recipe II) are investigated.•The experimental results show that the sensor based on an MFC with recipe I has detection limits of ∼77 ppb and ∼281 ppb to ethanol and methanol respectively.•Both sensors are demonstrated fast response times of less than 5 min, while the recovery times varied from 7 min to 12 min.•In addition, simultaneous measurement of ethanol and methanol by using another TSCSMF based sample (7.0 μm) coated with recipe II.
High sensitivity volatile organic compounds (VOCs) sensors based on a tapered small core single mode fiber (TSCSMF) and a microfiber coupler (MFC) are reported. The TSCSMF had a waist diameter of ∼5.1 μm and the MFC had a waist diameter of ∼1.9 μm each and both were fabricated using a customized microheater brushing technique. Silica based materials containing immobilized Nile red prepared by sol-gel method with two different recipes (recipe I and recipe II) are investigated. Initially recipe I based coating materials were applied to the surfaces of the TSCSMF and MFC. The experimental results show that the sensor based on an MFC shows much better sensitivities of −0.130 nm/ppm and −0.036 nm/ppm to ethanol and methanol than those of the TSCSMF based sensor. The corresponding minimum detectable concentration change of the MFC based sensor are calculated to be ∼77 ppb and ∼281 ppb to ethanol and methanol respectively. Both sensors are demonstrated fast response times of less than 5 min, while the recovery times varied from 7 min to 12 min. In addition, another TSCSMF based sample (∼7.0 μm) coated with a mixed layer of sol silica and Nile red prepared by recipe II was fabricated to achieve simultaneous measurement of ethanol and methanol, employing a second-order matrix approach.
Atmospheric drag is an important factor affecting orbit determination and prediction of low-orbit space debris. To obtain accurate ballistic coefficients of space debris, we propose a calculation ...method based on measured optical angles. Angle measurements of space debris with a perigee height below 1400 km acquired from a photoelectric array were used for orbit determination. Perturbation equations of atmospheric drag were used to calculate the semi-major-axis variation. The ballistic coefficients of space debris were estimated and compared with those published by the North American Aerospace Defense Command in terms of orbit prediction error. The 48 h orbit prediction error of the ballistic coefficients obtained from the proposed method is reduced by 18.65% compared with the published error. Hence, our method seems suitable for calculating space debris ballistic coefficients and supporting related practical applications.
Atmospheric drag is an important influencing factor in precise orbit determination and the prediction of low-orbit space debris. It has received widespread attention. Currently, calculating ...atmospheric drag mainly relies on different atmospheric density models. This experiment was designed to explore the impact of different atmospheric density models on the orbit prediction of space debris. In the experiment, satellite laser ranging data published by the ILRS (International Laser Ranging Service) were used as the basis for the precise orbit determination for space debris. The prediction error of space debris orbits at different orbital heights using different atmospheric density models was used as a criterion to evaluate the impact of atmospheric density models on the determination of space-target orbits. Eight atmospheric density models, DTM78, DTM94, DTM2000, J71, RJ71, JB2006, MSIS86, and NRLMSISE00, were compared in the experiment. The experimental results indicated that the DTM2000 atmospheric density model is best for determining and predicting the orbits of LEO (low-Earth-orbit) targets.
Initial orbit determination (IOD), as a basis for initial orbit association and accurate orbit determination (OD), has a crucial role in the process of obtaining space debris orbit information. Among ...the traditional methods, the Gooding method has better convergence and stability. In this study, the Gooding method is enhanced to solve the issues discovered. A novel initial orbit determination (IOD) method is developed using the proposed improvement measures of the single-parameter initial value determination (SIVD) method, the fitted-curve noise suppression method, the restricted corrective value solution method, the removal of trivial solutions, etc. The experimental results verify the effectiveness of the improved method. The success rate of the initial orbit determination reached 99%, and the accuracy of the solved orbit parameters was significantly improved, especially the semi-major axis (SMA) error of less than 50 km, accounting for 88% of the total. It can be seen that the method meets the demand of space-based space debris cataloging for initial orbit association and can serve in the field of space situational awareness, which has important practical significance and application potential.
Interferometer based on multiple beam interferences inside a hollow core fiber (HCF) structure (also known as an antiresonant reflecting optical waveguide) has been attracting interest of many ...researchers due to its periodic transmission spectrum containing high quality factor spectral dips. Functionalized HCF structures have been demonstrated for a wide range of applications in humidity, magnetic field, and biosensing. Here, we report a new application of the HCF-based structure with a partial silver coating layer for sensing of twist. It is configured by a fusion splicing a section of 4.5-mm long HCF between two standard single mode fibers (SMFs), followed by a sputter-coating of a very thin layer of silver on one side of the HCF surface. It is found that the spectral response of the partially silver coated HCF structure is very sensitive to the changes of input light polarization. An increase in sensitivity of the fiber structure to twist after deposition of the silver coating when the twist is applied to both the SMF and HCF sections is demonstrated by comparison with an uncoated HCF fiber structure. Experimental results show that twisting of the HCF section results in much greater changes in a selected dip's strength compared to that in the case of twisting the SMF section of the structure. The proposed HCF fiber sensors with 4.5-nm and 6.7 nm-thick silver layers show the highest sensitivities of 0.647 dB/°and 0.717 dB/° in the twist angles range of up to 10°. To the best of our knowledge, this is the highest twist sensitivity reported for intensity modulation-based fiber sensors. Moreover, the proposed sensor offers excellent measurement repeatability.
In scenarios such as nearshore and inland waterways, the ship spots in a marine radar are easily confused with reefs and shorelines, leading to difficulties in ship identification. In such settings, ...the conventional ARPA method based on fractal detection and filter tracking performs relatively poorly. To accurately identify radar targets in such scenarios, a novel algorithm, namely YOSMR, based on the deep convolutional network, is proposed. The YOSMR uses the MobileNetV3(Large) network to extract ship imaging data of diverse depths and acquire feature data of various ships. Meanwhile, taking into account the issue of feature suppression for small-scale targets in algorithms composed of deep convolutional networks, the feature fusion module known as PANet has been subject to a lightweight reconstruction leveraging depthwise separable convolutions to enhance the extraction of salient features for small-scale ships while reducing model parameters and computational complexity to mitigate overfitting problems. To enhance the scale invariance of convolutional features, the feature extraction backbone is followed by an SPP module, which employs a design of four max-pooling constructs to preserve the prominent ship features within the feature representations. In the prediction head, the Cluster-NMS method and α-DIoU function are used to optimize non-maximum suppression (NMS) and positioning loss of prediction boxes, improving the accuracy and convergence speed of the algorithm. The experiments showed that the recall, accuracy, and precision of YOSMR reached 0.9308, 0.9204, and 0.9215, respectively. The identification efficacy of this algorithm exceeds that of various YOLO algorithms and other lightweight algorithms. In addition, the parameter size and calculational consumption were controlled to only 12.4 M and 8.63 G, respectively, exhibiting an 80.18% and 86.9% decrease compared to the standard YOLO model. As a result, the YOSMR displays a substantial advantage in terms of convolutional computation. Hence, the algorithm achieves an accurate identification of ships with different trail features and various scenes in marine radar images, especially in different interference and extreme scenarios, showing good robustness and applicability.
Down syndrome (DS) is a genetic disorder caused by presence of extra copy of human chromosome 21. It is characterised by several clinical phenotypes. Motor dysfunction due to hypotonia is commonly ...seen in individuals with DS and its etiology is yet unknown. Ts1Cje, which has a partial trisomy (Mmu16) homologous to Hsa21, is well reported to exhibit various typical neuropathological features seen in individuals with DS. This study investigated the role of skeletal muscles and peripheral nerve defects in contributing to muscle weakness in Ts1Cje mice.
Assessment of the motor performance showed that, the forelimb grip strength was significantly (P<0.0001) greater in the WT mice compared to Ts1Cje mice regardless of gender. The average survival time of the WT mice during the hanging wire test was significantly (P<0.0001) greater compared to the Ts1Cje mice. Also, the WT mice performed significantly (P<0.05) better than the Ts1Cje mice in the latency to maintain a coordinated motor movement against the rotating rod. Adult Ts1Cje mice exhibited significantly (P<0.001) lower nerve conduction velocity compared with their aged matched WT mice. Further analysis showed a significantly (P<0.001) higher population of type I fibres in WT compared to Ts1Cje mice. Also, there was significantly (P<0.01) higher population of COX deficient fibres in Ts1Cje mice. Expression of Myf5 was significantly (P<0.05) reduced in triceps of Ts1Cje mice while MyoD expression was significantly (P<0.05) increased in quadriceps of Ts1Cje mice.
Ts1Cje mice exhibited weaker muscle strength. The lower population of the type I fibres and higher population of COX deficient fibres in Ts1Cje mice may contribute to the muscle weakness seen in this mouse model for DS.
Objective
We assessed whether hematoma expansion (HE) and favorable outcome differ according to type of intracerebral hemorrhage (ICH).
Methods
Among participants with ICH enrolled in the TICH‐2 ...(Tranexamic Acid for Hyperacute Primary Intracerebral Haemorrhage) trial, we assessed baseline scans for hematoma location and presence of cerebral amyloid angiopathy (CAA) using computed tomography (CT, simplified Edinburgh criteria) and magnetic resonance imaging (MRI; Boston criteria) and categorized ICH as lobar CAA, lobar non‐CAA, and nonlobar. The main outcomes were HE and favorable functional outcome. We constructed multivariate regression models and assessed treatment effects using interaction terms.
Results
A total of 2,298 out of 2,325 participants were included with available CT (98.8%; median age = 71 years, interquartile range = 60‐80 years; 1,014 female). Additional MRI was available in 219 patients (9.5%). Overall, 1,637 participants (71.2%) had nonlobar ICH; the remaining 661 participants (28.8%) had lobar ICH, of whom 202 patients had lobar CAA‐ICH (8.8%, 173 participants according to Edinburgh and 29 participants according to Boston criteria) and 459 did not (lobar non‐CAA, 20.0%). For HE, we found a significant interaction of lobar CAA ICH with time from onset to randomization (increasing risk with time, pinteraction < 0.001) and baseline ICH volume (constant risk regardless of volume, pinteraction < 0.001) but no association between type of ICH and risk of HE or favorable outcome. Tranexamic acid significantly reduced the risk of HE (adjusted odds ratio = 0.7, 95% confidence interval = 0.6–1.0, p = 0.020) without statistically significant interaction with type of ICH (pinteraction = 0.058). Tranexamic acid was not associated with favorable outcome.
Interpretation
Risk of HE in patients with lobar CAA‐ICH was not independently increased but seems to have different dynamics compared to other types of ICH. The time window for treatment of CAA‐ICH to prevent HE may be longer. ANN NEUROL 2022;92:921–930
•n-Heptane HCCI combustion under air and oxygen intake was compared.•n-Heptane auto-ignition postponed due to higher specific heat capacity as oxygen increase.•The increment of heat release fraction ...during low temperature reaction is studied.•Oxygen enrichment lead to suppressed negative temperature coefficient.•The mechanism of low temperature reaction enhancement as oxygen increase is investigated.
To take maximum advantage of the high efficiency of homogeneous charge compression ignition combustion mode and internal combustion Rankine cycle concept, in this study, the n-heptane auto-ignition characteristics have been investigated using a compression ignition internal combustion Rankine cycle engine test bench and a zero-dimensional thermodynamic model coupled with a detailed kinetic model. The n-heptane auto-ignition process shows that under both air and oxygen intake, a typical two-stage combustion in which oxygen enrichment has very minor effects on the n-heptane high temperature reaction. The higher specific heat capacity of oxygen compared with nitrogen leads to an overall increased specific heat capacity, which lowers the in-cylinder temperature during compression stroke, thereby delaying the low temperature reaction initial timing. The higher oxygen content also improves the H-atom abstraction, first O2 addition, second O2 addition and peroxyalkylhydroperoxide isomerization, thereby improving the overall reaction rate and the heat release fraction of low temperature reaction. As a result, the in-cylinder temperature at the end of low temperature reaction also increases, thereby shortening significantly the negative temperature coefficient duration compared with a combustion cycle using air as oxidizer.
In this paper, a microdisk resonator with two whispering-gallery modes (WGMs) is proposed for label-free biochemical sensing. According to the transmission responses of the two WGMs with different ...coupling gaps, there is the critical coupling status for the WGM (0, 36) while there is no critical coupling status for the WGM (1, 28). For the WGMs (0, 36) and (1, 28), the refractive index (RI) sensitivities of 45.8821 and 72.9402 nm/RIU are obtained, and the corresponding RI detection limits (DLs) of 8.5902 × 10 -4 and 1.9228 × 10 -3 RIU are achieved, respectively. Moreover, the proposed sensor also has the temperature sensitivities of 0.0730 and 0.0703 nm/K, which correspond to the temperature DLs of 0.1631 and 0.6263 K, respectively. By constructing a characteristic matrix, it is demonstrated that simultaneous measurement of the RI and temperature can be achieved.
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