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Mohd Alawi AH, Hudha K, Kadir ZA, Amer NH. Hysteresis Behavior Modeling of Magnetorheological Elastomers under Impact Loading Using a Multilayer Exponential-Based Preisach Model Enhanced with Particle Swarm Optimization. Polymers (Basel) 2023; 15:polym15092145. [PMID: 37177291 PMCID: PMC10181239 DOI: 10.3390/polym15092145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2023] [Revised: 04/27/2023] [Accepted: 04/28/2023] [Indexed: 05/15/2023] Open
Abstract
Magnetorheological elastomers (MREs) are a type of smart material that can change their mechanical properties in response to external magnetic fields. These unique properties make them ideal for various applications, including vibration control, noise reduction, and shock absorption. This paper presents an approach for modeling the impact behavior of MREs. The proposed model uses a combination of exponential functions arranged in a multi-layer Preisach model to capture the nonlinear behavior of MREs under impact loads. The model is trained using particle swarm optimization (PSO) and validated using experimental data from drop impact tests conducted on MRE samples under various magnetic field strengths. The results demonstrate that the proposed model can accurately predict the impact behavior of MREs, making it a useful tool for designing MRE-based devices that require precise control of their impact response. The model's response closely matches the experimental data with a maximum prediction error of 10% or less. Furthermore, the interpolated model's response is in agreement with the experimental data with a maximum percentage error of less than 8.5%.
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Affiliation(s)
- Alawiyah Hasanah Mohd Alawi
- Department of Mechanical Engineering, Faculty of Engineering, National Defence University of Malaysia, Kem Sungai Besi, Kuala Lumpur 57000, Malaysia
| | - Khisbullah Hudha
- Department of Mechanical Engineering, Faculty of Engineering, National Defence University of Malaysia, Kem Sungai Besi, Kuala Lumpur 57000, Malaysia
| | - Zulkiffli Abd Kadir
- Department of Mechanical Engineering, Faculty of Engineering, National Defence University of Malaysia, Kem Sungai Besi, Kuala Lumpur 57000, Malaysia
| | - Noor Hafizah Amer
- Department of Mechanical Engineering, Faculty of Engineering, National Defence University of Malaysia, Kem Sungai Besi, Kuala Lumpur 57000, Malaysia
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2
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Mostafa AMA, Zakaly HMH, Issa SAM, Uosif MAM, Alrowaili ZA, Zhukovsky MV. Exploring the Potential of Zirconium-89 in Diagnostic Radiopharmaceutical Applications: An Analytical Investigation. Biomedicines 2023; 11:biomedicines11041173. [PMID: 37189792 DOI: 10.3390/biomedicines11041173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 04/06/2023] [Accepted: 04/10/2023] [Indexed: 05/17/2023] Open
Abstract
This study highlights the use of 89Zr-oxalate in diagnostic applications with the help of WinAct and IDAC2.1 software. It presents the biodistribution of the drug in various organs and tissues, including bone, blood, muscle, liver, lung, spleen, kidneys, inflammations, and tumors, and analyzes the maximum amount of nuclear transformation per Bq intake for each organ. The retention time of the maximum nuclear transformation and the absorbed doses of the drug in various organs and tissues are also examined. Data from clinical and laboratory studies on radiopharmaceuticals are used to estimate the coefficients of transition. The accumulation and excretion of the radiopharmaceutical in the organs is assumed to follow an exponential law. The coefficients of transition from the organs to the blood and vice versa are estimated using a combination of statistical programs and digitized data from the literature. WinAct and IDAC 2.1 software are used to calculate the distribution of the radiopharmaceutical in the human body and to estimate the absorbed doses in organs and tissues. The results of this study can provide valuable information for the biokinetic modeling of wide-spectrum diagnostic radiopharmaceuticals. The results show that 89Zr-oxalate has a high affinity for bones and a relatively low impact on healthy organs, making it helpful in targeting bone metastases. This study provides valuable information for further research on the development of this drug for potential clinical applications.
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Affiliation(s)
- Ahmed M A Mostafa
- Physics Department, College of Science, Jouf University, Sakaka P.O. Box 2014, Saudi Arabia
| | - Hesham M H Zakaly
- Institute of Physics and Technology, Ural Federal University, Ekaterinburg 620002, Russia
- Physics Department, Faculty of Science, Al-Azhar University, Assiut Branch, Assiut 71524, Egypt
| | - Shams A M Issa
- Physics Department, Faculty of Science, Al-Azhar University, Assiut Branch, Assiut 71524, Egypt
- Department of Physics, Faculty of Science, University of Tabuk, Tabuk P.O. Box 47512, Saudi Arabia
| | - Mohamed A M Uosif
- Physics Department, College of Science, Jouf University, Sakaka P.O. Box 2014, Saudi Arabia
| | - Ziyad A Alrowaili
- Physics Department, College of Science, Jouf University, Sakaka P.O. Box 2014, Saudi Arabia
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3
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Khan U. Temperature, meal size and body size effects on the gastric evacuation of rainbow trout: modelling optimum and upper thermal limits. J Fish Biol 2022; 100:1388-1398. [PMID: 35338479 DOI: 10.1111/jfb.15049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 03/08/2022] [Accepted: 03/22/2022] [Indexed: 06/14/2023]
Abstract
This study examined the rate and course of gastric evacuation (GE) in rainbow trout Oncorhynchus mykiss in relation to meal size, body size and temperature. The GE experiments were performed on small (mean ± 95% C.I., 17.7 ± 0.5 cm total length), medium (22. 9 ± 0.2 cm) and large (28.3 ± 0.3 cm) rainbow trout fed meals of different sizes using commercial food pellets at water temperatures T ranging from 7.8°C to 19.2°C. Estimating the shape parameter of a general power function suggested that the square root function adequately described the GE in rainbow trout independently of meal size. The effects of total body length L and weight W on gastric evacuation rate (GER) were described by simple power functions. The square root function was further expanded by a temperature function with temperature optimum to describe the effect of temperature. The expanded square root function revealed a considerable effect of body size and temperature on the GER of rainbow trout. The GER increased exponentially with rising temperature, reached an optimum at c. 18.5°C and then declined abruptly to zero at c. 21°C. The GER of rainbow trout could thus be described by d S t d t = - 0.00152 L 0.75 e 0.08 T 1 - e 1.18 T - 20.9 S t (g h-1 ) or d S t d t = - 0.00440 W 0.26 e 0.08 T 1 - e 0.97 T - 21.1 S t (g h-1 ), where St is the current stomach content mass (g), and at post-prandial time t (h). These functions should prove useful to calculate total GE time as well as stomach fullness at different post-prandial times and therefore provide valuable information to develop optimal feeding strategies for farming of rainbow trout.
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Affiliation(s)
- Umar Khan
- Institute of Marine Sciences and Technology, Karadeniz Technical University, Trabzon, 61080, Turkey
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4
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Guimard A, Joulia F, Prieur F, Poszalczyk G, Helme K, Lhuissier FJ. Exponential Relationship Between Maximal Apnea Duration and Exercise Intensity in Non-apnea Trained Individuals. Front Physiol 2022; 12:815824. [PMID: 35145428 PMCID: PMC8821942 DOI: 10.3389/fphys.2021.815824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 12/22/2021] [Indexed: 11/13/2022] Open
Abstract
It is well known that the duration of apnea is longer in static than in dynamic conditions, but the impact of exercise intensity on the apnea duration needs to be investigated. The aim of this study was to determine the relationship between apnea duration and exercise intensity, and the associated metabolic parameters. Ten healthy active young non-apnea trained (NAT) men participated in this study. During the first visit, they carried out a maximum static apnea (SA) and a maximal progressive cycle exercise to evaluate the power output achieved at peak oxygen uptake (PVO2peak). During the second visit, they performed four randomized dynamic apneas (DAs) at 20, 30, 40, and 50% of PVO2peak (P20, P30, P40, and P50) preceded by 4 min of exercise without apnea. Duration of apnea, heart rate (HR), arterial oxygen saturation (SpO2), blood lactate concentration [La], rating of perceived exertion (RPE), and subjective feeling were recorded. Apnea duration was significantly higher during SA (68.1 ± 23.6 s) compared with DA. Apnea duration at P20 (35.6 ± 11.7 s) was higher compared with P30 (25.6 ± 6.3 s), P40 (19.2 ± 6.7 s), and P50 (16.9 ± 2.5 s). The relationship between apnea duration and exercise intensity followed an exponential function (y = 56.388e-0.025 x ). SA as DA performed at P20 and P30 induces a bradycardia. Apnea induces an SpO2 decrease which is higher during DA (-10%) compared with SA (-4.4%). The decreases of SPO2 recorded during DA do not differ despite the increase in exercise intensity. An increase of [La] was observed in P30 and P40 conditions. RPE and subjective feeling remained unchanged whatever the apnea conditions might be. These results suggest that the DA performed at 30% of VO2peak could be the best compromise between apnea duration and exercise intensity. Then, DA training at low intensity could be added to aerobic training since, despite the moderate hypoxia, it is sufficient to induce and increase [La] generally observed during high-intensity training.
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Affiliation(s)
- Alexandre Guimard
- Université Sorbonne Paris Nord, Hypoxie et Poumon, H&P, INSERM, UMR 1272, Bobigny, France.,Département STAPS, Université Sorbonne Paris Nord, Bobigny, France
| | - Fabrice Joulia
- Center for Cardiovascular and Nutrition Research (C2VN), INSERM 1263, INRAE 1260, Aix Marseille Université, Marseille, France.,UFR STAPS, Toulon, France
| | - Fabrice Prieur
- Université Paris-Saclay, CIAMS, Orsay, France.,Université d'Orléans, CIAMS, Orléans, France
| | - Gauthier Poszalczyk
- Université Sorbonne Paris Nord, Hypoxie et Poumon, H&P, INSERM, UMR 1272, Bobigny, France.,Département STAPS, Université Sorbonne Paris Nord, Bobigny, France
| | - Kader Helme
- Université Sorbonne Paris Nord, Hypoxie et Poumon, H&P, INSERM, UMR 1272, Bobigny, France.,Département STAPS, Université Sorbonne Paris Nord, Bobigny, France
| | - François J Lhuissier
- Université Sorbonne Paris Nord, Hypoxie et Poumon, H&P, INSERM, UMR 1272, Bobigny, France.,Assistance Publique - Hôpitaux de Paris, Hôpitaux Universitaires Paris Seine-Saint-Denis, Hôpital Jean Verdier, Médecine de l'Exercice et du Sport, Bondy, France
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5
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Wu L, Hu S, Liu C. Exponential-Distance Weights for Reducing Grid-like Artifacts in Patch-Based Medical Image Registration. Sensors (Basel) 2021; 21:s21217112. [PMID: 34770418 PMCID: PMC8588231 DOI: 10.3390/s21217112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 10/19/2021] [Accepted: 10/21/2021] [Indexed: 11/17/2022]
Abstract
Patch-based medical image registration has been well explored in recent decades. However, the patch fusion process can generate grid-like artifacts along the edge of patches for the following two reasons: firstly, in order to ensure the same size of input and output, zero-padding is used, which causes uncertainty in the edges of the output feature map during the feature extraction process; secondly, the sliding window extraction patch with different strides will result in different degrees of grid-like artifacts. In this paper, we propose an exponential-distance-weighted (EDW) method to remove grid-like artifacts. To consider the uncertainty of predictions near patch edges, we used an exponential function to convert the distance from the point in the overlapping regions to the center point of the patch into a weighting coefficient. This gave lower weights to areas near the patch edges, to decrease the uncertainty predictions. Finally, the dense displacement field was obtained by this EDW weighting method. We used the OASIS-3 dataset to evaluate the performance of our method. The experimental results show that the proposed EDW patch fusion method removed grid-like artifacts and improved the dice similarity coefficient superior to those of several state-of-the-art methods. The proposed fusion method can be used together with any patch-based registration model.
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Affiliation(s)
- Liang Wu
- School of Control Science and Engineering, Shandong University, Jinan 250061, China;
| | - Shunbo Hu
- School of Information Science and Engineering, Linyi University, Linyi 276005, China
- Correspondence: (S.H.); (C.L.)
| | - Changchun Liu
- School of Control Science and Engineering, Shandong University, Jinan 250061, China;
- Correspondence: (S.H.); (C.L.)
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Yi Z, Huang Z, Lai S, He W, Wang L, Chi F, Zhang C, Shui L, Zhou G. Driving Waveform Design of Electrowetting Displays Based on an Exponential Function for a Stable Grayscale and a Short Driving Time. Micromachines (Basel) 2020; 11:mi11030313. [PMID: 32188157 PMCID: PMC7142935 DOI: 10.3390/mi11030313] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 03/09/2020] [Accepted: 03/12/2020] [Indexed: 11/29/2022]
Abstract
The traditional driving waveform of the electrowetting display (EWD) has many disadvantages, such as the large oscillation of the target grayscale aperture ratio and a long time for achieving grayscale. Therefore, a driving waveform based on the exponential function was proposed in this study. First, the maximum driving voltage value of 30 V was obtained by testing the hysteresis curve of the EWD pixel unit. Secondly, the influence of the time constant on the driving waveform was analyzed, and the optimal time constant of the exponential function was designed by testing the performance of the aperture ratio. Lastly, an EWD panel was used to test the driving effect of the exponential-function-driving waveform. The experimental results showed that a stable grayscale and a short driving time could be realized when the appropriate time constant value was designed for driving EWDs. The aperture ratio oscillation range of the gray scale could be reduced within 0.95%, and the driving time of a stable grayscale was reduced by 30% compared with the traditional driving waveform.
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Affiliation(s)
- Zichuan Yi
- College of Electron and Information, University of Electronic Science and Technology of China, Zhongshan Institute, Zhongshan 528402, China; (Z.Y.); (F.C.); (C.Z.); (L.S.)
| | - Zhenyu Huang
- Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China; (W.H.); (L.W.); (G.Z.)
- Shenzhen Guohua Optoelectronics Tech. Co., Ltd., Shenzhen 518110, China;
- Correspondence: ; Tel.: +86-0755-2941-5855
| | - Shufa Lai
- Shenzhen Guohua Optoelectronics Tech. Co., Ltd., Shenzhen 518110, China;
| | - Wenyao He
- Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China; (W.H.); (L.W.); (G.Z.)
| | - Li Wang
- Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China; (W.H.); (L.W.); (G.Z.)
- Shenzhen Guohua Optoelectronics Tech. Co., Ltd., Shenzhen 518110, China;
| | - Feng Chi
- College of Electron and Information, University of Electronic Science and Technology of China, Zhongshan Institute, Zhongshan 528402, China; (Z.Y.); (F.C.); (C.Z.); (L.S.)
| | - Chongfu Zhang
- College of Electron and Information, University of Electronic Science and Technology of China, Zhongshan Institute, Zhongshan 528402, China; (Z.Y.); (F.C.); (C.Z.); (L.S.)
| | - Lingling Shui
- College of Electron and Information, University of Electronic Science and Technology of China, Zhongshan Institute, Zhongshan 528402, China; (Z.Y.); (F.C.); (C.Z.); (L.S.)
- Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China; (W.H.); (L.W.); (G.Z.)
| | - Guofu Zhou
- Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China; (W.H.); (L.W.); (G.Z.)
- Shenzhen Guohua Optoelectronics Tech. Co., Ltd., Shenzhen 518110, China;
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7
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Stegall SE, Collette T, Kinjo T, Takahashi T, Romanowich P. Quantitative Cross-Cultural Similarities and Differences in Social Discounting for Gains and Losses. Front Public Health 2019; 7:297. [PMID: 31696100 PMCID: PMC6817477 DOI: 10.3389/fpubh.2019.00297] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 10/02/2019] [Indexed: 11/24/2022] Open
Abstract
Social discounting is when resource allocation decreases as social distance increases. Studies fitting different quantitative models to social discounting data have shown that a q-exponential function based on Tsallis' statistics best fits loss data, whereas a hyperbolic power function best fits gain data. However, a social discounting sign effect, where losses are discounted less than equivalent gains, has not been consistently found. This study fit four different quantitative social discounting models to gain and loss data for 40 United States (US) participants. We compared quantitative model fits to previous studies collected with Japanese and German participants to determine if (1) different quantitative social discounting models best fit loss and gain data, (2) US participants discounted less gains than Japanese participants, but not losses, and (3) US participants showed the sign effect. Results showed that the q-exponential function and the hyperbolic power function best fit median loss and gain data, respectively. There were no significant absolute differences between cultures for gains or losses, and US participants showed a robust sign effect. While most results for US participants were consistent with previous data, future cross-cultural social discounting studies are needed that manipulate sign as well as reward magnitude to determine best quantitative model fits. Social discounting results are also discussed in relation to their application to important health behaviors such as smoking and obesity.
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Affiliation(s)
- Sarah E. Stegall
- Department of Psychology, The University of Texas at San Antonio, San Antonio, TX, United States
| | - Tyler Collette
- Department of Psychology, The University of Texas at San Antonio, San Antonio, TX, United States
| | - Takuji Kinjo
- Department of Behavioral Science, Hokkaido University, Sapporo, Japan
| | - Taiki Takahashi
- Department of Behavioral Science, Hokkaido University, Sapporo, Japan
| | - Paul Romanowich
- Department of Psychology, Gonzaga University, Spokane, WA, United States
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Chen X, Pickwell-MacPherson E. A Sensitive and Versatile Thickness Determination Method Based on Non-Inflection Terahertz Property Fitting. Sensors (Basel) 2019; 19:s19194118. [PMID: 31547626 PMCID: PMC6806189 DOI: 10.3390/s19194118] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 09/12/2019] [Accepted: 09/22/2019] [Indexed: 11/24/2022]
Abstract
The accuracy of thin-film characterization in terahertz spectroscopy is mainly set by the thickness uncertainty. Physical thickness measurement has limited accuracy for thin-film samples thinner than a few hundreds of micrometers and is sometimes even impossible. The temporal resolution of time-domain terahertz spectrometers is not sufficient to resolve such thin films. Previously reported numerical methods mainly only work for materials with low dispersion and absorption. Here, we propose a novel method for thickness determination by fitting a non-inflection offset exponential function to the material optical properties. Theoretical analysis predicts the best fitting to only be achieved when the correct thickness is given. Transmission measurements on a thin-film polymer, water, and a lactose pallet verify the theory and show the accurate thickness determination and property characterization on materials which are either achromatic or dispersive, transparent or absorptive, featureless or resonant. The measurements demonstrate the best versatility and sensitivity compared to the state-of-art. The method could be widely adapted to various types of research and industrial applications.
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Affiliation(s)
- Xuequan Chen
- Department of Electronic Engineering, The Chinese University of Hong Kong, Hong Kong 999077, China.
| | - Emma Pickwell-MacPherson
- Department of Electronic Engineering, The Chinese University of Hong Kong, Hong Kong 999077, China.
- Physics Department, Warwick University, Coventry CV4 7AL, UK.
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9
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Xu S, Zhou H, Wang J, He Z, Wang D. SINS/CNS/GNSS Integrated Navigation Based on an Improved Federated Sage-Husa Adaptive Filter. Sensors (Basel) 2019; 19:E3812. [PMID: 31484447 DOI: 10.3390/s19173812] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 08/18/2019] [Accepted: 08/29/2019] [Indexed: 11/22/2022]
Abstract
Among the methods of the multi-source navigation filter, as a distributed method, the federated filter has a small calculation amount with Gaussian state noise, and it is easy to achieve global optimization. However, when the state noise is time-varying or its initial estimation is not accurate, there will be a big difference with the true value in the result of the federated filter. For the systems with time-varying noise, adaptive filter is widely used for its remarkable advantages. Therefore, this paper proposes a federated Sage–Husa adaptive filter for multi-source navigation systems with time-varying or mis-estimated state noise. Because both the federated and the adaptive principles are different in updating the covariance of the state noise, it is required to weight the two updating methods to obtain a combined method with stability and adaptability. In addition, according to the characteristics of the system, the weighting coefficient is formed by the exponential function. This federated adaptive filter is applied to the SINS/CNS/GNSS integrated navigation, and the simulation results show that this method is effective.
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10
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Xu Y, Zhou T. Research on In-Flight Alignment for Micro Inertial Navigation System Based on Changing Acceleration using Exponential Function. Micromachines (Basel) 2018; 10:mi10010024. [PMID: 30598021 PMCID: PMC6356345 DOI: 10.3390/mi10010024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 12/17/2018] [Accepted: 12/19/2018] [Indexed: 11/16/2022]
Abstract
In order to guarantee the stable flight of a guided projectile, it is difficult to realize in-flight alignment for the micro inertial navigation system (MINS) during its short flight time. In this paper, a method based on changing acceleration using exponential function is proposed. First, double-vector observations were derived. Then the initial attitude for the guided projectiles was estimated by the regressive quaternion estimation (QUEST) algorithm. Further, the estimated errors were analyzed, and the reason for using the changing acceleration for the in-flight alignment was explained. A simulation and semi-physical experiment was performed to show the effectiveness of the proposed method. The results showed that the initial attitude error for the rolling angle was about 0.35°, the pitch angle was about 0.1° and the heading angle was about 0.6°, in which the initial shooting angle was between 15° and 55°. In future studies, the field experiments will be carried out to test the stability of the proposed in-flight alignment for guided projectiles.
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Affiliation(s)
- Yun Xu
- School of Mechanical Engineering & Automation, Zhejiang Sci-Tech University, Hangzhou 310018, China.
| | - Tong Zhou
- School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
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11
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Wang J. Systematic analysis of residual density suggests that a major limitation in well-refined X-ray structures of proteins is the omission of ordered solvent. Protein Sci 2017; 26:1012-1023. [PMID: 28244185 DOI: 10.1002/pro.3145] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Revised: 02/21/2017] [Accepted: 02/23/2017] [Indexed: 12/23/2022]
Abstract
In the residual electron density map of a fully refined X-ray protein model, there should be no peaks arising from modeling errors or missing atoms. Any residual peaks that do occur should be contributed by random residual intensity differences between the model and the data. If the model is incomplete (i.e., some atoms are missing), there will be more positive peaks than negative ones. On the other hand, if the model includes inappropriately located atoms, there will be an excess of negative peaks. In this study, random residual peaks are quantified using the probability density function P(x), which is defined as the probability for a peak having peak height between x and x + dx. It is found that P(x) is single-exponential and symmetric for both positive and negative peaks. Thus, P(x) can be used to discriminate residual peaks contributed by random noise in complete models from residual peaks being attributable to modeling errors in incomplete models. For a number of representative structures in the PDB it is found that P(x) has far more large (greater than 5 sigma) positive peaks than large negative peaks. This excess of large positive peaks suggests that the main defect in these refined structures is the omission of ordered water molecules.
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Affiliation(s)
- Jimin Wang
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, 06520
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12
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Hanounik SB, Osborne WW, Pirie WR. Relationships between the population density of Meloidogyne incognita and growth of tobacco. J Nematol 1975; 7:352-356. [PMID: 19308181 PMCID: PMC2620134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023] Open
Abstract
Seedlings of tobacco cultivars resistant (NC95) and susceptible (McNair 30) to Meloidogyne incognita were grown in 15-cm diameter clay pots containing steamed soil infested with 0, l, 2, 4, 8, 16, 32, and 64 eggs of M. incognita per 1.5 cm(3) soil. Plants were maintained in the greenhouse for 3 weeks, and then transferred to the field for 12 weeks. Growth of tobacco was expressed separately as dry weight of leaves and as plant height. Least squares regression analysis showed that tobacco growth-nematode density interactions are in agreement with Seinhorst's exponential model Y = m + (l-m) czp. Tobacco growth was not affected significantly as nematode density was increased from 0 to tolerance levels, which were approximately 2 and 1 eggs per 1.5 cm(3) soil for the resistant and susceptible cultivars, respectively. As nematode density was increased beyond tolerance level, tobacco growth decreased sharply until a minimum yield was approached. The minimum leaf weights and plant heights of the resistant cultivar at the highest nematode density were greater than those of the susceptible cultivar.
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