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Experimental study of rain affected optical wireless link to investigate regression parameters for tropical Indian monsoon

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OPTICAL AND QUANTUM ELECTRONICS 2023年第4期55卷 384-384页

作者： Soni, Gireesh G. Tripathi, Abhishek Shroti, Manaswi Agarwal, Kushagra Shri G S Inst Technol & Sci Dept Elect & Instrumentat Engn Appl Phys & Optoelect Indore India Kalasalingam Acad Res & Educ Dept Comp Sci & Engn Srivilliputhur India

The prediction of rain rate and corresponding attenuation is a vital parameter to be considered while analyzing a terrestrial free space optical (FSO) communication link. Actual tropical rainfall occurs for 15% of the year, therefore hourly data of rain rate must be accurately estimated for higher rainfall sites. This paper is concerned with the empirical determination of the power-law coefficients that allow for the development of a rain model. The measured attenuation for tropical rainy weather significantly varies from defined International Telecom Union (ITU-R) standard. The experimental work is examined using optimized laser wavelength, launched power and link range. The purpose of the study is to obtain the regression parameters (k and alpha ) for rain specific attenuation (RSA) applicable to tropical weather conditions. The test rain channel is imitated in the laboratory, where a 10 Mb/s, 1550 nm on-off keying (OOK) signal is propagated through the rain closet chamber of 0.5 x 0.5 x 5 m(3). The effective optical link of 15 m is made using round-trip reflection by plane mirrors, and a concave mirror is used to gather irradiance onto the receiver aperture. The average RSA is measured from collected data for maximum rain intensity of 210 mm/h for the Indian monsoon. The testbed analyses FSO link in terms of received optical power, bit error rate (BER) and Q-factor. Using the least square mean equation approach, k and a are estimated to be 0.63 and 0.91, respectively. The finding contributes to reporting power margin and improving the system performance for deploying an optical link in areas of higher rain intensity.

关键词： FSO Rainfall rate Tropical weather Rain specific attenuation regression parameters Prediction model Test chamber

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Two-stage estimation and bias-corrected empirical likelihood in a partially linear single-index varying-coefficient model

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JOURNAL OF THE ROYAL STATISTICAL SOCIETY SERIES B-STATISTICAL METHODOLOGY 2023年第4期85卷 1299-1325页

作者： Xue, Liugen Henan Univ Sch Math & Stat North Sect Jinming Ave Kaifeng 475004 Henan Peoples R China

The estimation and empirical likelihood (EL) of the parameters of interest in a partially linear single-index varying-coefficient model are studied. A two-stage method is presented to estimate the regression parameters and the coefficient functions. The asymptotic distributions of the proposed estimators are obtained. Meanwhile, a bias-corrected EL ratio for the regression parameters is proposed. It is shown that the ratio is asymptotically standard chi-squared. The result can be directly used to construct the EL confidence regions of the regression parameters. Simulation studies are carried out to evaluate the finite sample behaviour of the proposed method. An application example of a real data set is given.

关键词： two-stage method bias-corrected empirical likelihood regression parameters confidence region pointwise confidence interval

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Biometric indices of eight fish species from the catchment area of Kaptai lake, Bangladesh

ECOLOGICAL FRONTIERS

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ECOLOGICAL FRONTIERS 2024年第5期44卷 1061-1068页

作者： Rahman, Md. Khaled Rahman, B. M. Shahinur Lima, Rabina Akther Ali, Azhar Mahmud, Yahia Bangladesh Fisheries Res Inst Riverine Sub Stn Rangamati 4500 Bangladesh Bangladesh Fisheries Res Inst Shrimp Res Stn Bagerhat 9300 Bangladesh Bangladesh Fisheries Res Inst Freshwater Sub Stn Saidpur 5310 Bangladesh Bangladesh Fisheries Res Inst Mymensingh 2201 Bangladesh

Biometric indices viz. i) Length-weight relationships (LWRs), ii) form factor (a(0.3)) and iii) condition factors (relative K-R and Fulton's K-F) were presented for 8 fish species collected from Kaptai lake at five sampling points including Rangamati Sadar, Barkal, Naniarchar, Langadu and Kaptai upazila. A total of 3204 individuals belonging to 3 families were measured and weighed between August 2020 to April 2021 by the catch assessment survey with different types of fishing gear (seine net, current net, gill net and lift net). Calculations were made for the parameters a and b of the eq. W = aTL(b). The analysis of covariance (ANCOVA) revealed significant differences between stations in LWRs for all species (P < 0.01). The parameter b of the LWRs ranged from 2.34 (Parambassis lala) to 3.34 (Ailia coila) with a mean value of 2.98 (SE: 0.11) and 50% of its fall within the interval 2.9-3.2. Results showed that 3 species showed positive allometric growth (Gonialosa manminna, Ailia coila, and Eutropiichthys vacha), 3 showed negative allometric growth (Gudusia chapra, Chanda baculis, and Parambassis lala), and 2 exhibited isometric growth (Corica soborna, Chanda nama). The findings further indicated that the LWRs of 8 species were highly correlated (r(2) > 0.90, P < 0.001). The a(3.0) value estimated for eight species varied from 0.0043 to 0.0114. The K-R value ranged from 0.26 to 4.97 and K-F value ranged from 0.17 to 2.89;showed significant differences of K-R and K-F between stations for eight species. As per FishBase, a new record for the maximum size of C. soborna and C. baculis was documented as 7.1 cm and 8.1 cm, respectively. This research is the first to provide information on biometric indices for six species (C. soborna, C. nama, C. baculis, P. lala, A. coila and E. vacha) in Kaptai Lake, which may aid in management and conservation throughout the country, including their geographical distribution.

关键词： Length-weight relationships Form factor regression parameters Condition factor Kaptai Lake Bangladesh

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Length-Weight Relationship and Condition Factor of Sixteen Demersal Fish Species from the Southern part of the Marmara Sea, Turkey

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JOURNAL OF ICHTHYOLOGY 2022年第4期62卷 543-551页

作者： Karadurmus, U. Bandirma Onyedi Eylul Univ Maritime Vocat Sch Dept Underwater Technol Balikesir Turkey

The Marmara Sea is an important acclimatization zone and biological transition for the biota of the Mediterranean Sea and the Black Sea. Overfishing, pollution, and changes due to global climate change put constant pressure on marine organisms in the Sea of Marmara. Therefore, monitoring and management of fishery resources of the Sea of Marmara have specific importance. The health level and temporal variation of 16 different demersal fish species in the Sea of Marmara were investigated based on length-weight relationship parameters and condition factors. Five of them are new length-weight relationship records in the Sea of Marmara (Raja miraletus, Lepidorhombus boscii, Scophthalmus maximus, Trachinus draco and Zeus faber);additional records expand the known size range for six species (Mullus surmuletus, R. clavata, Scorpaena porcus, Scyliorhinus canicula, Squalus acanthias and Torpedo marmorata). The values of a (intercept) varied between 0.0024 and 0.0564, whereas the b (slope) values varied between 2.6284 and 3.2084. The coefficient of determination was relatively high in most species (R-2 >= 0.95), except for S. porcus and T. marmorata. The condition factor of some species (Merlangius merlangus, Merluccius merluccius, M. barbatus, L. boscii, S. maximus, Solea solea, S. acanthias, T. marmorata and Z. faber) were low (K < 1). The results obtained can be beneficial for the fisheries management and conservation purpose of studied species in future studies.

关键词： length-weight relationship fish growth condition factor population dynamics regression parameters Marmara Sea

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Monthly variations in growth pattern and condition factor of Periophthalmodon septemradiatus (Gobiiformes: Periophthalminae) living along the Bassac River in Viet Nam

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PEERJ 2022年 10卷 e13880页

作者： Quang Minh Dinh Ton Huu Duc Nguyen Ngon Trong Truong Diep Xuan Doan Tien Thi Kieu Nguyen Can Tho Univ Sch Educ Dept Biol Can Tho Vietnam Can Tho Univ Biotechnol Res & Dev Inst Dept Mol Biotechnol Can Tho Vietnam Van Lang Univ Van Lang Sch Engn & Technol Med Chem Hitech Agr & Bioact Cpds Res Grp Ho Chi Minh City Vietnam An Khanh High Sch Dept Biol Can Tho Can Tho Vietnam

Periophthalmodon septemradiatus (Hamilton, 1822) is a unique mudskipper living in the mudbanks from estuarine to riverine regions in the Vietnamese Mekong Delta (VMD), but there is no data on its growth patterns and condition factors that are helpful for fish resource assessment and adaptation understanding. This study was conducted at five sites, from the lower (Soc Trang province) to middle (Can Tho city) and upper (An Giang province) reaches of Bassac River in VMD, to provide knowledge on growth patterns and condition factors to this mudskippers. Fish samples were caught using traps and hands for 24 months, from July 2017 to June 2019, at these five sites. The total length and weight of 3,417 individuals (1,340 females and 2,077 males) varied by sex, season and site (p < 0.001 for all cases). This species exhibited a positive allometric type as the slope (b = 3.06 +/- 0.01) of the length-weight relationship (LWR) was >3 (p < 0.001) for both sexes. The growth pattern changed with sex as mudskipper showed isometry in females but positive allometry in males. Maturity also affected fish growth type since it shifted from negative allometry in immature groups to positive allometry in mature groups. The growth pattern of fish changed from isometry in the dry season to positive allometry in the wet season. The mudskipper showed isometry at the lower reaches in Soc Trang but positive allometry at the middle and upper reaches in Can Tho and An Giang. The condition factor (CF) did not change according to sex, size and season, but with month and site variables. The present environmental condition in these studied sites tended to be not good enough for this fish as CF (0.95 +/- 0.01) was less than 1 (p < 0.001). The findings provided basic information on the growth and adaptation of P. septemradiatus being helpful in fish adaptation understanding an d resource conservation in VMD.

关键词： Fish growth Isometry Length-weight relationship Mekong Delta Negative allometry regression parameters

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Statistical Analysis of the Dynamics of Coronavirus Cases using Stepwise Switching regression

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CYBERNETICS AND SYSTEMS ANALYSIS 2020年第6期56卷 943-952页

作者： Knopov, P. S. Korkhin, A. S. Natl Acad Sci Ukraine VM Glushkov Inst Cybernet Kiev Ukraine Pridneprovskaya Acad Construct & Architecture Dnipro Ukraine

The dynamics of coronavirus cases is proposed to be modeled using switching regression whose switching points are unknown. The stepwise process of constructing the regression in time is described. The dynamics of the ... 详细信息

关键词： regression switching points regression parameters stepwise estimation infection coronavirus

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An Approximate Method of Constructing a Switching regression with Unknown Switch Points

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CYBERNETICS AND SYSTEMS ANALYSIS 2020年第3期56卷 426-438页

作者： Korkhin, A. S. Prydniprovska State Acad Civil Engn & Architectur Dnipro Ukraine

The method is applicable to regressions whose variables are time series. The estimation method is based on the fact that these series are considered as observed values of continuous random functions of time. This property makes it possible to solve the estimation problem using gradient methods for optimization problems. Examples of using the proposed method are given.

关键词： regression switch points regression parameters continuous time discrete time estimation

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Continuous-Time Switching regression Method with Unknown Switching Points

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CYBERNETICS AND SYSTEMS ANALYSIS 2020年第1期56卷 68-80页

作者： Knopov, P. S. Korkhin, A. S. Natl Acad Sci Ukraine VM Glushkov Inst Cybernet Kiev Ukraine Prydniprovska State Acad Civil Engn & Architectur Dnipro Ukraine

Linear regression with switching in continuous time is considered. A method for estimation of switching points and switching regression parameters is described. Examples of its use are given.

关键词： regression continuous time switching regression parameters evaluation

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Evaluation of gray box thermostatic expansion valve mass flow models

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INTERNATIONAL JOURNAL OF REFRIGERATION-REVUE INTERNATIONALE DU FROID 2018年 96卷 161-168页

作者： Behfar, Alireza Yuill, David Univ Nebraska Coll Engn Durham Sch Architectural Engn & Construct Peter Kiewit Inst 1110 South 67th St Omaha NE 68182 USA

Thermostatic expansion valves (TXVs) are widely used in air-conditioning and commercial refrigeration systems. Accurate predictions of the refrigerant mass flow rate across a refrigeration cycle are desired in many engineering processes and applications such as a computer simulation model, for control purposes, or for fault detection and diagnostics (FDD). Several researchers have developed mass flow models for TXVs. This paper reviews and analyzes four gray-box TXV mass flow models in the literature and evaluates and compares their performance. Three of the models were developed for air-conditioners, but in the current work their applicability to refrigeration system modeling is assessed, with the use of normal and faulted laboratory data from a commercial walk-in cooler and a freezer. Model regression parameters are calculated during the training process with the use of parameter estimation techniques and a training dataset. The models are then used to predict the mass flow rates for several validation data points. Each of the models is found to perform well for the majority of the data points for the freezer, typically with errors below 10%, but application of the models to the cooler's dataset resulted in relatively large errors. The source of the model deviations includes the difficulty associated with the calculation of the TXV diaphragm force and the thermodynamic states of a two-phase refrigerant at the inlet of the valve. The presence of a liquid line receiver, which are common in refrigeration equipment, appears to cause some model deviation. (C) 2018 Elsevier Ltd and IIR. All rights reserved.

关键词： Mass flow rate TXV models Gray-box regression parameters

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Constructing a Switching regression with Unknown Switching Points

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CYBERNETICS AND SYSTEMS ANALYSIS 2018年第3期54卷 443-455页

作者： Korkhin, A. S. Natl Mining Univ Dnipro Ukraine

Switching regression is considered in the case where switching points are unknown. A general method is described to estimate switching points and parameters of linear regression with switching. Examples of its use are... 详细信息

关键词： regression switching regression parameters evaluation

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