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Boulder-induced form roughness and skin shear stresses in a gravel-bed stream

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Journal of Mountain Science 2024年第1期21卷 346-360页

作者： DAS ratul DATTA Akash Civil Engineering Department National Institute of Technology AgartalaAgartala-799046India

Boulder spacing in mountain rivers and near-wake flow zones within the boulder array is very useful for fish habitat and growth of aquatic *** present study aims to investigate how the boulder array and spacing influence the near-bed flow structures in a gravel-bed *** are staggered over a gravel-bed stream with three different inter-boulder spacing namely(a)large(b)medium and(c)small *** acoustic Doppler velocimeter was used for flow measurements in a rectangular channel and the results were compared with those acquired from numerical *** time-averaged velocity profiles at the near-wake flow zones of boulders experience maximum flow retardation which is an outcome of the boulder-induced form *** ratio of velocity differences associated to form and skin roughness and its positive magnitude reveals the dominance of form roughness closest to the *** roughness computed is 1.75 to 2 times higher than the skin roughness at the near-wake flow *** particular,the collective immobile boulders placed at different inter-boulder spacings developed high and low bed shear stresses closest to the *** low bed shear stresses characterised by a secondary peak developed at the trough location of the boulders is attributed to the skin shear ***,the spatial averaging of time-averaged flow quantities gives additional impetus to present an improved illustration of fluid shear *** formation of form-induced shear stress is estimated to be 17%to 23%of doubleaveraged Reynolds shear stress and partially compensates for the damping of time-averaged Reynolds shear stress in the interfacial *** quadrant analysis of spatial velocity fluctuations depicts that the form-induced shear stresses are dominant in the interfacial sub-layer and have no significance above the gravel-bed surface.

关键词： Array of boulders Near wake flow zones Velocity distributions Skin roughness Form induced shear stresses

Prevalence of Argulus sp. in Indian Major Carps from Bhangore Block of South 24 Parganas District, West Bengal, India

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Journal of Fisheries Science 2020年第1期2卷 5-8页

作者： ratul chakraborty Debapriyo Mukherjee Avishek Bardhan Prasenjit Mali Koel Bhattacharya Sanyal Gadadhar Dash Department of Aquatic Animal Health Faculty of Fishery SciencesWest Bengal University of Animal and Fishery Sciences(WBUAFS)5-Budherhat RoadChakgaria CampusP.O.PanchasayarKolkata-700094West BengalIndia

The study was carried out to find the prevalence and severity of Argulus *** Indian Major Carps(IMCs)collected from Bhangore block of South 24 Parganas district of West Bengal during November 2018 to August ***(2019)recorded the highest parasitic prevalence(PFI,83.33%)and the month of August(2019)recorded the lowest parasitic prevalence(PFI,9%).The identities of selected parasites were further confirmed by molecular identification through 18S rDNA *** study revealed that Argulus *** had great economic implications especially in the winter months and is one of the most prevalent problems in fresh water aquaculture systems.

关键词： Argulus Bhangore Indian major carps Parasites Prevalence Severity

Moisture regime influence on soil carbon stock and carbon sequestration rates in semi-arid forests of the National Capital Region, India

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Journal of Forestry Research 2020年第6期31卷 2323-2332页

作者： Urvashi Tomar ratul Baishya Department of Botany University of DelhiDelhi 110007India

Understanding the dynamics of soil carbon is crucial for assessing the soil carbon storage and predicting the potential of mitigating carbon dioxide from the atmosphere to the biomass and *** present study evaluated variations of soil carbon stock in semi-arid forests in India under diff erent moisture *** organic carbon(SOC)and soil inorganic carbon(SIC)stocks were determined in diff erent moisture regimes ***,post-monsoon,winter and pre-monsoon seasons at 0–10 and>10–20 cm *** stock showed signifi cant variations under different moisture *** highest SOC stock was during winter(22.81 Mg C ha−1)and lowest during the monsoon season(2.34 Mg C ha−1)among all the ridge forests under *** and SIC stock under diff erent moisture regimes showed signifi cant negative correlation with soil moisture(p<0.05),as a sudden increase in soil moisture after rainfall results in an increase in carbon loss due to microbial decomposition of accumulated carbon during the dry *** was an increase in annual SOC stock and a decrease(or no change in some cases),in SIC stock at both the depths during the study *** SOC and SIC sequestration rates were estimated as any increase/decrease in the respective stock during each successive *** sequestered ranged between 0.046 and 0.741 Mg C ha−1 y−***,SIC sequestration ranged between 0.013 and 0.023 Mg C ha−1 y−1 over all ridge forests up to 20 cm *** Delhi ridge forests,which accounts to 0.007%of the semi-arid regions of India,contribute 0.25–0.32%of the national potential(semi-arid region)for SOC sequestration up to 20 cm *** estimates of the rate of C sequestration in this study provide a realistic image of carbon dynamics under present climatic conditions of semi-arid forests,and could be used in developing a database and formulating new strategies for carbon dioxide mitigation by enhancing soil C sequestration rates.

关键词： Soil organic carbon Soil inorganic carbon Carbon sequestration Moisture regime Semi-arid forests

Stand structure and species diversity regulate biomass carbon stock under major Central Himalayan forest types of India

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Ecological Processes 2021年第1期10卷 195-212页

作者： Siddhartha Kaushal ratul Baishya Ecology&Ecosystem Research Laboratory Department of BotanyUniversity of DelhiDelhi 110007India

Background:Data on the impact of species diversity on biomass in the Central Himalayas,along with stand structural attributes is sparse and ***,few studies in the region have related population structure and the influence of large trees on *** data is crucial for maintaining Himalayan biodiversity and carbon ***,we investigated these relationships in major Central Himalayan forest types using nondestructive methodologies to determine key factors and underlying ***:Tropical Shorea robusta dominant forest has the highest total biomass density(1280.79 Mg ha^(−1))and total carbon density(577.77 Mg C ha^(−1))along with the highest total species richness(21 species).The stem density ranged between 153 and 457 trees ha^(−1) with large trees(>70 cm diameter)contributing 0–22%.Conifer dominant forest types had higher median diameter and Cedrus deodara forest had the highest growing stock(718.87 m^(3) ha^(−1));furthermore,*** contributed maximally toward total carbon density(14.6%)among all the 53 species *** semecarpifolia–Rhododendron arboreum association forest had the highest total basal area(94.75 m^(2) ha^(−1)).We found large trees to contribute up to 65%of the growing *** percent of the species contributed more than 50%of the carbon *** dominance regulated the growing stock significantly(R^(2)=0.707,p<0.001).Temperate forest types had heterogeneous biomass distribution within the forest *** found total basal area,large tree density,maximum diameter,species richness,and species diversity as the predominant variables with a significant positive influence on biomass carbon *** structural attributes and diversity influenced the ordination of study sites under PCA *** showed no significant correlation with either biomass or species diversity ***:The results suggest biomass hyperdominance with both selection effects and niche complementarit

关键词： Biomass hyperdominance Elevational gradient Growing stock Large trees Carbon allocation Forest management

Seasonality and moisture regime control soil respiration, enzyme activities, and soil microbial biomass carbon in a semi-arid forest of Delhi, India

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Ecological Processes 2020年第1期9卷 579-591页

作者： Urvashi Tomar ratul Baishya Ecology&Ecosystem Research Laboratory Department of BotanyUniversity of DelhiDelhi 110007India

Soil respiration,soil enzymes,and microbial biomass are important in carbon cycling in the terrestrial ecosystem which is generally limited by environmental factors and soil carbon ***,we tried to assess the factors affecting the functional aspects of these processes in a semi-arid *** monitored soil respiration(surface)using a portable infrared gas analyzer(Q-Box SR1LP Soil Respiration Package,Qubit Systems,Canada)equipped with a soil respiration chamber(Model:G 180).Soil respiration was measured at midday during each season throughout the study *** enzymatic activities and microbial biomass carbon(MBC)were analyzed following the standard protocol for a year during peak time in four seasons at 0-10 cm and 10-20 cm *** respiration shows significant variation with highest in monsoon(3.31μmol CO2 m−2 s^(−1))and lowest in winter(0.57μmol CO2 m^(−2) s^(−1)).Similarly,β-glucosidase,dehydrogenase,and phenol oxidase activity ranged from 11.15 to 212.59μg PNP g^(−1) DW h^(−1),0.11 to 16.47μg TPF g^(−1) DW h^(−1),and 4102.95 to 10187.55μmol ABTS+g^(−1) DW min^(−1),*** ranged from 17.08 to 484.5μgCg^(−1).Besides,soil respiration,soil enzymes(exceptβ-glucosidase),and MBC were significantly correlated with soil ***,optimum moisture and temperature played a significant role in determining variations in soil microbiological processes(exceptβ-glucosidase activity);the carbon cycling in the study area is assisted by enzyme activity;dehydrogenase and phenol oxidase played a significant role in soil respiration;hence,this landscape is sensitive to environmental changes.

关键词： Soil respiration Enzyme activities Microbial biomass carbon Seasons Semi-arid forest

State of Safety Prediction of Power Lithium Ion Batteries in Context of Aging and Capacity Fade for Electric Vehicles

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State of Safety Prediction of Power Lithium Ion Batteries in...

作者： ratul 西南科技大学

学位级别：硕士

在现代时代,电池成为一种强大的替代能源,选择锂离子化学电池技术是这种能源系统的高效选择。然而,锂离子电池安全应用始终是重要的问题。研究表明,作为电池管理系统的重要指标,安全状态与电池安全使用紧密相关。但是,测量可靠的安全状... 详细信息

在现代时代,电池成为一种强大的替代能源,选择锂离子化学电池技术是这种能源系统的高效选择。然而,锂离子电池安全应用始终是重要的问题。研究表明,作为电池管理系统的重要指标,安全状态与电池安全使用紧密相关。但是,测量可靠的安全状态非常困难,因为它的值不能由传感器直接计算,并且还没有准确的解决方案。到目前为止,基于模型的方法是对动态安全状态预测的有效解决方案。因此作为一项临时研究,本研究工作利用电池老化模型和容量衰减模型,提出了一种可靠的高功率锂离子电池状态安全预测方法。为了完成这项研究工作中的准确安全评估状态,请遵循以下过程,1.将安全状态定义为电池老化和容量衰减的函数。2.根据内阻增长建立了电池老化模型。3.进行混合脉冲功率特性测试以识别参数。4.引入“Knee-Arrhenius算法”以识别电池的容量衰减。5.合并子模型输出,并确定电池的安全状态。子模型的输出是新引入的寿命终止索引的寿命终止状态。两种模型的寿命终止值分别通过传统的内部电阻计算,混合脉冲功率特性测试方法和建议的“Knee-Arrhenius”算法方法来计算。每个模型研究的老化现象是循环老化。实验研究包括三个实验过程:评估循环老化的循环寿命,验证电池老化模型的混合脉冲功率特性测试以及验证容量衰减模型的容量特性测试。所有实验均在25°C恒温条件下进行。曲线拟合结果显示出较低的R-平方误差率（0.98?0.99）,并且表明实验设计和数学分析符合锂离子电池的动态特性。此外,在锂离子电池的典型使用寿命内,提出的“拐点-阿伦尼乌斯”算法也显示出有效且较早的拐点估计值,错误率小于0.15%。

关键词：锂离子电池安全状态生命的尽头拐点算法 Arrhenius模型容量衰减 Knee-Arrhenius算法

Exploring the influencing factors for non-utilisation of healthcare facilities during childbirth:a special mixed-method study of Bangladesh and 13 other low-and middle-income countries based on Demographic and Health Survey data

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Family Medicine and Community Health 2019年第4期7卷 1-9页

作者： Tanjim Siddiquee Henry ratul Halder Md Akhtarul Islam Statistics Discipline Khulna UniversityKhulnaBangladesh

Objective To identify the associated factors affecting the decision regarding institutional delivery for pregnant women in 14 low-and middle-income countries(LMICs).Design A special mixed-method design was used to combine cross-sectional studies for harmonising data from Bangladesh and 13 other countries to obtain extended viewpoints on non-utilisation of institutional healthcare facilities during *** Demographic and Health Survey(DHS)data for 14 LMICs were used for the *** There are several kinds of datasets in the *** them‘Individual Women’s Records’was used as this study is based on all ever-married *** In the binary logistic and meta-analysis models for Bangladesh,ORs for birth order were 0.57 and 0.51 and for respondents’age were 1.50 and 1.07,*** all 14 LMICs,the most significant factors for not using institutional facilities during childbirth were respondents’age(OR 0.903,95%CI 0.790 to 1.032)and birth order(OR 0.371,95%CI 0.327 to 0.421).Conclusion Birth order and respondents’age were the two most significant factors for non-utilisation of healthcare facilities during childbirth in 14 LMICs.

关键词： income mixed birth

Face Mask and Social Distance Monitoring via Computer Vision and Deployable System Architecture

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Intelligent Automation & Soft Computing 2023年第3期35卷 3641-3658页

作者： Meherab Mamun ratul Kazi Ayesha Rahman Javeria Fazal Naimur Rahman Abanto Riasat Khan Department of Electrical and Computer Engineering North South UniversityDhakaBangladesh

The coronavirus(COVID-19)is a lethal virus causing a rapidly infec-tious disease throughout the *** awareness,taking preventive mea-sures,imposing strict restrictions on public gatherings,wearing facial masks,and maintaining safe social distancing have become crucial factors in keeping the virus at *** though the world has spent a whole year preventing and curing the disease caused by the COVID-19 virus,the statistics show that the virus can cause an outbreak at any time on a large scale if thorough preventive measures are not maintained ***ﬁght the spread of this virus,technologically developed systems have become very ***,the implementation of an automatic,robust,continuous,and lightweight monitoring system that can be efﬁciently deployed on an embedded device still has not become prevalent in the mass *** paper aims to develop an automatic system to simul-taneously detect social distance and face mask violation in real-time that has been deployed in an embedded system.A modiﬁed version of a convolutional neural network,the ResNet50 model,has been utilized to identify masked faces in *** Only Look Once(YOLOv3)approach is applied for object detection and the DeepSORT technique is used to measure the social *** efﬁciency of the proposed model is tested on real-time video sequences taken from a video streaming source from an embedded system,Jetson Nano edge computing device,and smartphones,Android and iOS *** results show that the implemented model can efﬁciently detect facial masks and social distance viola-tions with acceptable accuracy and precision scores.

关键词： Artiﬁcial intelligence COVID-19 deep learning technique face mask detection social distance monitor you only look once

Blue carbon sequestration following mangrove restoration:evidence from a carbon neutral case in China

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Ecosystem Health and Sustainability 2022年第1期8卷 471-485页

作者： Sourav Bagchi ratul Xiaoxuan Gu Peiyang Qiao Febrina Wulanda Sagala Shu Nan Nazrul Islam Luzhen Chen State Key Laboratory of Marine Environmental Science Key Laboratory of the Ministry of Education for Coastal and Wetland EcosystemsCollege of the Environment and EcologyXiamen UniversityXiamenFujianChina Forestry and Wood Technology Discipline Khulna UniversityKhulnaBangladesh

Sequestration of blue carbon(C)in mangrove plantations depends on site characteristics and plantation *** study evaluated the effects of plantation management on C sequestration at a C-neutral site in Xiamen,China.A field study was conducted on 10-year-old Sonneratia apetala and Kandelia obovata plantations(mono-Sa,mono-Ko)and a 15-year-old mixed plantation-.We found that mono-Ko had a significantly higher ecosystem C sequestration rate(3.32±0.62 kg C m^(-2)yr^(-1))than others when planted in the indirect shade of pioneer *** a non-native species,Sonneratia performed better(0.57±0.01 kg C m^(-2)yr^(-1))when planted with Kandelia than in monotypic *** temporary and long-term certified emission reduction(tCER and lCER)of the 12.98 ha mono-Ko was 4103.89 and 3693.50 net CO_(2)-e within 10 years,respectively.A literature review was conducted to show the compatibility of this study with other natural and plantation sites of China and Bangladesh(the native habitat for Sonneratia).The C sequestration of Sonneratia plantation sites in China is comparable with those in ***,the soil C accumulation rate for a Sonneratia monotypic plantation in Bangladesh decreased with age,yet the same did not occur in the plantations of China.

关键词： Blue carbon mangrove carbon density carbon accumulation plantation type