signal change
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Atmosphere ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 109
Chengzhi Xiang ◽  
Ailin Liang

In the CO2 differential absorption lidar (DIAL) system, signals are simultaneously collected through analog detection (AD) and photon counting (PC). These two kinds of signals have their own characteristics. Therefore, a combination of AD and PC signals is of great importance to improve the detection capability (detection range and accuracy) of CO2-DIAL. The traditional signal splicing algorithm cannot meet the accuracy requirements of CO2 inversion due to unreasonable data fitting. In this paper, a piecewise least square splicing algorithm is developed to make signal splicing more flexible and efficient. First, the lidar signal is segmented, and according to the characteristics of each signal, the best fitting parameters are obtained by using the least square fitting with different steps. Then, all the segmented and fitted signals are integrated to realize the effective splicing of the near-field AD signal and the far-field PC signal. A weight gradient strategy is also adopted in signal splicing, and the weights of the AD and PC signals in the spliced signal change with the height. The splicing effect of the improved algorithm is evaluated by the measured signal, which are obtained in Wuhan, China, and the splice of the AD and PC signals in the range of 800–1500 m are completed. Compared with the traditional method, the evaluation parameter R2 and the residual sum of squares of the spliced signal are greatly improved. The linear relationship between the AD and PC signals is improved, and the fitting R2 of differential absorption optical depth reaches 0.909, indicating that the improved signal splicing algorithm can well splice the near-field AD signal and the far-field PC signal.

2021 ◽  
Vol 22 (7) ◽  
pp. 1661-1672
Sheng Dong Sheng Dong ◽  
Jibiao Zhou Sheng Dong ◽  
Shuichao Zhang Jibiao Zhou ◽  
Lin Guo Shuichao Zhang ◽  
Zhijian Wang Lin Guo

2021 ◽  
Vol 24 (3) ◽  
pp. 28-45
Ivan P. Ohrymenko ◽  
Nikolai N. Kolchevsky ◽  
Pavel P. Petrov

The general principles of gravitational waves detection are considered in this paper. Current gravitational wave detectors represent modernized Michelson interferometer LIGO-detector. Reduction of vibrations in the system and high stabilization of the reflective mirrors is one of the technical problem of the LIGO. It is proposed to study the features of the LIGO-detector with movable mirrors. The software simulating the operation of the LIGO and providing an opportunity to study its characteristics and capacity is developed and named LIGO-RM. The primary goal of the modelling is to study the signal of the gravitational waves detector with oscillating mirrors. The LIGO-RM contains graphic user interface (GUI) that provides interactive control of mirrors movement nature and monitoring of detector signal change. The software simulates the presence of gravitational wave of a requested type and makes it able to monitor its effect on the operation results of the LIGO interferometer in interactive mode or as a numerical outcome. A range of numerical experiments is conducted and the signals on the detector with and without mirrors oscillations are shown. The results of calculations and a possibility of the registration of the gravitational waves using the LIGO-detector with movable mirrors are discussed.

Sensors ◽  
2021 ◽  
Vol 21 (22) ◽  
pp. 7567
Seokhwan Kim ◽  
Jinjoo Han ◽  
Heeseok Chung ◽  
Yong-Keun Choi ◽  
Ayemeh Bagheri Hashkavayi ◽  

In recent years, cerium oxide (CeO2) nanoparticles (NPs) have drawn significant attention owing to their intrinsic enzyme mimetic properties, which make them powerful tools for biomolecular detection. In this work, we evaluated the effect of pyrophosphate (PPi) on the oxidase activity of CeO2 NPs. The presence of PPi was found to enhance the oxidase activity of CeO2 NPs, with enhanced colorimetric signals. This particular effect was then used for the colorimetric detection of target nucleic acids. Overall, the PPi-enhanced colorimetric signals of CeO2 NPs oxidase activity were suppressed by the presence of the target nucleic acids. Compared with previous studies using CeO2 NPs only, our proposed system significantly improved the signal change (ca. 200%), leading to more sensitive and reproducible colorimetric analysis of target nucleic acids. As a proof-of-concept study, the proposed system was successfully applied to the highly selective and sensitive detection of polymerase chain reaction products derived from Klebsiella pneumoniae. Our findings will benefit the rapid detection of nucleic acid biomarkers (e.g., pathogenic bacterial DNA or RNA) in point-of-care settings.

Polymers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3755
Xin Lu ◽  
Konstantin Hicke ◽  
Mathias Breithaupt ◽  
Christoph Strangfeld

We present a preliminary investigation on distributed humidity monitoring during the drying process of concrete based on an embedded polymer optical fiber (POF). The water dissipated into the POF changes several properties of the fiber such as refractive index, scattering coefficient and attenuation factor, which eventually alters the Rayleigh backscattered light. The optical time domain reflectometer (OTDR) technique is performed to acquire the backscattered signal at the wavelengths 650 nm and 500 nm, respectively. Experimental results show that the received signal increases at 650 nm while the fiber attenuation factor clearly increases at 500 nm, as the concrete dries out. In the hygroscopic range, the information retrieved from the signal change at 650 nm agrees well with the measurement result of the electrical humidity sensors also embedded in the concrete sample.

2021 ◽  
Vol 15 ◽  
Jiayu Xiao ◽  
Matthew M. Padrick ◽  
Shlee S. Song ◽  
Zhaoyang Fan ◽  
Konrad H. Schlick

Intracranial atherosclerotic disease (ICAD) is a dynamic process that leads to ischemic stroke. Symptomatic ICAD patients still suffer a high recurrent rate even under standard treatment. In this case report, to better understand the response of intracranial atherosclerotic plaques to medication, serial MR imaging was added to standard clinical workup in a 47-year-old male patient with acute occipital lobe infarction at baseline, 3-month, 6-month, and 12-month post index stroke to directly visualize the morphology and signal change of plaques. We noticed that one of the plaques showed dramatic worsening at 3-month imaging follow-up despite a decrease in low-density lipoprotein level. Early identification of patients who do not respond well to medication is critical to prevent the recurrence of cardiovascular events in ICAD patients.

2021 ◽  
Vol 11 (1) ◽  
pp. 69-90
Åke Viberg

The paper focuses on the role of the Swedish spatial particles upp ‘up’ and ner ‘down’ to signal the endpoint-of-motion in the description of motion situations and is based on Swedish original fiction texts and their translations into English, German, French and Finnish. Frequently the endpoint is marked with a locative preposition such as på ‘on’ or i ‘in’, and then a particle is required to signal change-of-place. In German and Finnish, the particle is often zero translated and change-of-place is indicated by case. The particle is often zero translated also in French, a V(erb)-framed language. This leads to contrasts at the conceptual level since verticality is not expressed. The result points to radical intra-typological differences between S(atellite)-framed languages in the expression of Path depending on general morpho-syntactic differences. Another important conclusion is that several different classes of motion verbs must be distinguished even in S-languages to describe the expression of change-of-place.

2021 ◽  
Vol 33 (1) ◽  
Eui Yub Jung ◽  
Seongmin Jeong ◽  
Sun-Kyu Kim ◽  
Sung-Sahn Lee ◽  
Dong Jin Ryu ◽  

Abstract Purpose The purpose of this study is to classify the discoid lateral meniscus (DLM) according to the signal and shape in magnetic resonance imaging (MRI), and to provide information not only in diagnosis but also in treatment. Materials and Methods We reviewed 162 cases who diagnosed with DLM by MRI and underwent arthroscopic procedures from April 2010 to March 2018. Three observers reviewed MRI findings of all cases and predicted arthroscopic tear using three MRI criteria (criterion 1,2 and 3). Among three criteria, the criterion that most accurately predicts arthroscopic tear was selected. Using this criterion, the cases of predicted tear were named group 1. In addition, group 1 was divided into three subgroups (group 1a, 1b and 1c) by deformation or displacement on MRI and arthroscopic type of tear and procedures were analyzed according to these subgroups. Results The intra-meniscal signal change itself (criterion 3) on MRI showed the highest agreement with the arthroscopic tear. No meniscal deformation and displacement on MRI (group 1a) showed no specific type of tear and more cases of meniscal saucerization. The meniscal deformation on MRI (group 1b) showed more simple horizontal tears and more cases of meniscal saucerization. The meniscal displacement on MRI (group 1c) showed more peripheral tears and more cases of meniscal repair and subtotal meniscectomy. Comparing arthroscopic type of tear and type of arthroscopic procedure between three subgroups, there were significant differences in three groups (P < .05). Conclusions Intra-meniscal signal change itself on MRI is the most accurate finding to predict arthroscopic tear in symptomatic DLM. In addition, subgroup analysis by deformation or displacement on MRI is helpful to predict the type of arthroscopic tear and procedures.

2021 ◽  
Vol 29 (3) ◽  
pp. 230949902110472
Hiroko Iwakawa ◽  
Shigeharu Uchiyama ◽  
Yasunari Fujinaga ◽  
Masanori Hayashi ◽  
Masatoshi Komatsu ◽  

Purpose We aimed to evaluate the extent of collagenase clostridium histolyticum (CCH) diffusion in Dupuytren’s contracture (DC) for tissues outside of the contracture cord using Magnetic Resonance Imaging (MRI) immediately after CCH injection. Methods: 10 male patients aged 57–79 with DC of the metacarpophalangeal (MCP) joints were examined. Extension deficits were 10–60°(mean, 34.3) and 0–60°(mean, 26.6) in the MCP and proximal interphalangeal (PIP) joints, respectively. CCH injection was performed according to the standard method. MRI was performed within 15 min of CCH injection. Results: In all 10 cases, the extended area of high-intensity signal change outside of the cord was observed on short-T1 inversion recovery images (STIRs). Continuity from the insertion site was observed in the area of signal change involving the flexor tendon and neurovascular bundle. The signal change area spanned distally and proximally beyond the injection level. The signal change area expanded along the tendon sheath but no signal changes were observed inside the flexor tendon, suggesting the tendon sheath serves as a protective barrier from the CCH solution. After 1 week of injection, the mean decrease in contracture was 32.5°(94.7%) for the MCP joint and 19.8°(74.4%) for the PIP joint. In nine out of 10 cases, the extension deficit was within five degrees of full extension in the affected finger. There was no neurovascular injury or tendon rupture at 3 months of observation. Conclusions: MRI indicated the possible leakage of the drug outside of the cord during the early phase after administration, suggesting that CCH could persistently affect healthy tissues until CCH inactivates its enzyme process.

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