Journal of Water Supply Research and Technology-aqua最新文献_第6页

Evaluation of the groundwater recharge potential zone by using the GIS and remote sensing in the Ziway Abijata sub-basin, Central Rift Valley of Ethiopia 基于GIS和遥感的埃塞俄比亚中部裂谷Ziway Abijata次盆地地下水补给潜力区评价

IF 4.3

Journal of Water Supply Research and Technology-aqua Pub Date : 2023-07-21 DOI: 10.2166/ws.2023.183

M. Badasa, Mengistu Muleta Gurmessa, Geda Feyera Negasa, Dereje Oljira, Misgana Lamessa Dinsa, Kiros Tsegay Deribew, Zenebe Reta Roba, D. O. Gemeda

{"title":"Evaluation of the groundwater recharge potential zone by using the GIS and remote sensing in the Ziway Abijata sub-basin, Central Rift Valley of Ethiopia","authors":"M. Badasa, Mengistu Muleta Gurmessa, Geda Feyera Negasa, Dereje Oljira, Misgana Lamessa Dinsa, Kiros Tsegay Deribew, Zenebe Reta Roba, D. O. Gemeda","doi":"10.2166/ws.2023.183","DOIUrl":"https://doi.org/10.2166/ws.2023.183","url":null,"abstract":"\u0000 \u0000 Groundwater is fresh water that is stored in an underground zone, which is less vulnerable to pollution than surface water and communally used for economic, social, and ecological purposes. This study aimed to evaluate groundwater recharge potential by using a geographic information system (GIS) and remote sensing in the Ziway Abijata sub-basin, Central Rift Valley of Ethiopia. In the present study, six parameters such as soil drainage, slope, lineament density, drainage density, soil texture, and land use land cover were used. ArcGIS 10.3, ERDAS Imagine 2015, IDRISI Selva 17, Arc SWAT 10.3, and Google Earth Pro were applied. The results revealed that about 58 km2 (2.1%) and 1442.5 km2 (53.9%) were ranked as excellent and good for the groundwater recharge potential. Consequently, about 1183.2 km2 (43.4%) was covered by a moderate groundwater recharge zone. Larger parts of the study area were dominated by good and moderate groundwater recharge zones. Based on the results of this study, we recommended that the decision-makers, environmentalists, geologists, and other stakeholders will have a critical role in the improvements of the future sustainability and proper management of groundwater in the study area. Further researchers can investigate other remaining ecological parameters and socio-economic data that were not included in the present study.","PeriodicalId":17553,"journal":{"name":"Journal of Water Supply Research and Technology-aqua","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2023-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73495484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A method for water supply network DMA partitioning planning based on improved spectral clustering 一种基于改进谱聚类的供水管网DMA分区规划方法

IF 4.3

Journal of Water Supply Research and Technology-aqua Pub Date : 2023-07-20 DOI: 10.2166/ws.2023.180

Qiansheng Fang, Hongyu Zhao, Chenlei Xie, Tao Chen

{"title":"A method for water supply network DMA partitioning planning based on improved spectral clustering","authors":"Qiansheng Fang, Hongyu Zhao, Chenlei Xie, Tao Chen","doi":"10.2166/ws.2023.180","DOIUrl":"https://doi.org/10.2166/ws.2023.180","url":null,"abstract":"In recent years, the scale and complexity of water distribution networks (WDNs) have been increasing with the acceleration of urbanization process. It has become a hot research focus to use district metering area (DMA) for more efficient management and control of WDNs. This article proposes a multistage DMA planning method based on improved weighted spectral clustering and genetic algorithm, aiming to address issues such as high investment cost and large differences in the water network demand distribution. First, the actual case pipe network is transformed into an undirected weighted graph based on graph theory, and a similarity matrix is formed by combining the physical properties and hydraulic characteristics of the water network. Then, based on the similarity matrix, the weighted spectral clustering algorithm is used to preliminarily divide the WDN, and the performance of the water supply pipe network formed with different division quantities and different weighting schemes is discussed. Finally, the genetic algorithm is used to optimize the arrangement of valves and flow meters on boundary pipes to generate the final configuration of DMA. The results show that the proposed method has a significant improvement in pipe network topology, hydraulic performance index, and economy compared with the traditional DMA method.","PeriodicalId":17553,"journal":{"name":"Journal of Water Supply Research and Technology-aqua","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79476709","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Simulation of groundwater dynamic conditions in the Baiquan spring region under optimal groundwater resource allocation 地下水资源优化配置下百泉泉地区地下水动态条件模拟

IF 4.3

Journal of Water Supply Research and Technology-aqua Pub Date : 2023-07-19 DOI: 10.2166/ws.2023.179

Kaidi Yan, Demin Liu

{"title":"Simulation of groundwater dynamic conditions in the Baiquan spring region under optimal groundwater resource allocation","authors":"Kaidi Yan, Demin Liu","doi":"10.2166/ws.2023.179","DOIUrl":"https://doi.org/10.2166/ws.2023.179","url":null,"abstract":"\u0000 Xingtai, once a famous city for its spring groups in history, has become one of the regions in the country where water resources are in high demand due to the long-term over-exploitation of groundwater resources. In the region where the springs in the area have dried up and been cutting off over the years, including Baiquan and Dahuo. In order to allocate the amount of water diverted from the Middle Section of the South-North Water Diversion Project reasonably, to effectively make the springs re-rushing and restore the groundwater level, this research established a numerical groundwater model based on the hydrogeological conditions of the study area. The calculated model is used to discuss the hydrodynamical patterns changes and predict the flow rate of spring groups under different allocations of supplement diversion schemes quantifiably. It was found that the scheme of using the amount of river diversion to rehabilitate the Xingtai urban funnel was most conducive to the recovery of groundwater levels in the spring groups, which is due to the reduction in groundwater extraction and has reduced the influence range of the urban funnel and improved the hydrodynamic conditions in the northern preferential runoff zone. The results have demonstrated the feasibility of re-rushing the spring groups.","PeriodicalId":17553,"journal":{"name":"Journal of Water Supply Research and Technology-aqua","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2023-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78713285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

IF 4.3

Journal of Water Supply Research and Technology-aqua Pub Date : 2023-07-18 DOI: 10.2166/ws.2023.175

Hari Krishna, Jeeoot Singh, V. Dwivedi, D. Singh

{"title":"Effect of dissimilarity of N and mass flow rates on yearly overall energy, exergy, and efficiency of PVT-FPC included dual-slope solar desalting units","authors":"Hari Krishna, Jeeoot Singh, V. Dwivedi, D. Singh","doi":"10.2166/ws.2023.175","DOIUrl":"https://doi.org/10.2166/ws.2023.175","url":null,"abstract":"\u0000 \u0000 This research paper investigates the impact of variation in the number of collectors (N) and mass flow rate (ṁfr) on yearly overall energy, exergy, and efficiency of a dual-slope solar desalting unit incorporated with N number of photovoltaic thermal flat plate collectors (NPVT-FPC-DSU). The denouement of this research work will be useful for the designer and installer of such a system in deciding the number of collectors according to the requirement. An exhaustive calculation is carried out considering all four kinds of climatic conditions in each month of the year for the weather of New Delhi, India. Fundamental equations of NPVT-FPC-DSU and all pertinent sets of values have been dined to the data processing code developed in MATLAB to estimate annual freshwater production, energy, thermal and electrical exergies, overall energy, exergy, and efficiency. Finally, values of these parameters except annual overall electrical energy recede with the augmentation in ṁfr value, and they become approximately constant exceeding ṁfr value of 0.10 kg/s. Conversely, an increase in the values of the above-mentioned parameters has been obtained with the increase in the value of N. Moreover, the optimum value of N is found to be 4 and 8 from yearly overall energy and exergy efficiency viewpoints, respectively.","PeriodicalId":17553,"journal":{"name":"Journal of Water Supply Research and Technology-aqua","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2023-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79876217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Water footprint assessment and its importance in Indian context: a meta-review 水足迹评估及其在印度背景下的重要性:一项荟萃综述

IF 4.3

Journal of Water Supply Research and Technology-aqua Pub Date : 2023-07-17 DOI: 10.2166/ws.2023.174

M. Mehla, M. Kothari, Pardeep Singh, S. R. Bhakar, K. Yadav

{"title":"Water footprint assessment and its importance in Indian context: a meta-review","authors":"M. Mehla, M. Kothari, Pardeep Singh, S. R. Bhakar, K. Yadav","doi":"10.2166/ws.2023.174","DOIUrl":"https://doi.org/10.2166/ws.2023.174","url":null,"abstract":"\u0000 \u0000 With the increasing population and per capita demand for freshwater, the burden of natural resources has increased many folds. Indian agriculture is still largely dependent on conventional methods of crop production that are mainly inefficient. Water security is essential for social and economic development, having an indispensable role in enhancing health, well-being, and economic progress, particularly in a developing country like India. Water footprint (WF) is an important indicator that helps ascertain the direct and indirect use of water in any process. WF modeling in agriculture enables us to pinpoint the impacts and limitations of the current crop production system. Assessing vulnerabilities across various regions and time helps us prepare actions to improve water productivity and promote sustainable water use. There is considerable spatial variability in blue, green, and gray WF among the different states of India due to their varied climate, soil, and topographic characteristics. WF assessment is critical for developing water allocation strategies, planning water trade, making policies, and implementing remedial measures. This paper describes the significance of WF and its proper management for sustainable crop production in India.","PeriodicalId":17553,"journal":{"name":"Journal of Water Supply Research and Technology-aqua","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2023-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89949644","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A catastrophe identification method for rainfall time series coupled sequential Mann-Kendall algorithm and Bernaola Galvan algorithm: a case study of the Qinglong River watershed, China 降雨时间序列耦合序列Mann-Kendall算法和Bernaola Galvan算法的突变识别方法——以青龙河流域为例

IF 4.3

Journal of Water Supply Research and Technology-aqua Pub Date : 2023-07-17 DOI: 10.2166/ws.2023.176

Xingpo Liu, Chenchen Jia, Yaozhi Chai

{"title":"A catastrophe identification method for rainfall time series coupled sequential Mann-Kendall algorithm and Bernaola Galvan algorithm: a case study of the Qinglong River watershed, China","authors":"Xingpo Liu, Chenchen Jia, Yaozhi Chai","doi":"10.2166/ws.2023.176","DOIUrl":"https://doi.org/10.2166/ws.2023.176","url":null,"abstract":"\u0000 \u0000 The identification of rainfall catastrophe characteristics is important for rainfall consistency testing in hydrostatistical analysis. In this study, a new classification framework method (trend, mean and change-rate catastrophe) coupled Sequential Mann-Kendall (SQ-MK) algorithm and Bernaola-Galvan heuristic segmentation (B-G) algorithm was proposed, and a rainfall catastrophe identification scheme was carried out for the Qinglong River watershed, Northern China. Meanwhile, the accuracy of catastrophe identification was improved by the robustness of the algorithm and the parameter optimization method of the B-G algorithm. Results revealed that (1) the most significant point of trend catastrophe in the Qinglong River watershed was in 1997. The trend catastrophe identification based on the SQ-MK algorithm was sensitive to the length of time series. (2) The sensitivity of parameter P0 (Range value (R) = 2.889) in the B-G algorithm was greater than that of parameter l0 (R = 0.333). The mean catastrophe points for the Qinglong River watershed were in 1997, 2002 and 2009. (3) The mean catastrophe identification based on the B-G algorithm was insensitive to the length of time series. (4) There was no change-rate catastrophe point in the Qinglong River watershed. Trend catastrophe and mean catastrophe did not necessarily lead to change-rate catastrophe.","PeriodicalId":17553,"journal":{"name":"Journal of Water Supply Research and Technology-aqua","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2023-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77305799","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Performance evaluation of pilot-scale reverse osmosis spiral wound membrane for water desalination systems 用于海水淡化系统的中试反渗透螺旋缠绕膜性能评价

IF 4.3

Journal of Water Supply Research and Technology-aqua Pub Date : 2023-07-17 DOI: 10.2166/ws.2023.172

Mohamed Allam, H. Soussa, Ezzat Elalfy

{"title":"Performance evaluation of pilot-scale reverse osmosis spiral wound membrane for water desalination systems","authors":"Mohamed Allam, H. Soussa, Ezzat Elalfy","doi":"10.2166/ws.2023.172","DOIUrl":"https://doi.org/10.2166/ws.2023.172","url":null,"abstract":"\u0000 The increasing scarcity of potable water increases the demand for non-conventional potable water resources such as desalination. Experiments are carried out using a pilot-scale device of the desalination process for three configurations of membrane allocation inside the pressure vessel. Configuration (A) is one pressure vessel containing one spiral wound membrane (SWM), (B) is four pressure vessels each containing one SWM connected in parallel, and (C) is one pressure vessel containing four membranes connected in parallel. The effect of applied pressure, temperature, and water salinity is studied. Moreover, a mathematical model using Ansys Fluent was developed and verified using the experimental data. The mathematical model is applied to an idealized case of an actual desalination plant. The main findings are (1) Configuration (B) and (C) accomplished higher permeate discharge comparing to (A) by an average percentage of 60 and 50, respectively, while (C) has the lowest output salinity by 30% from configuration (A). (2) The mathematical model is found to reduce the operating pressure of the plant by 8%.","PeriodicalId":17553,"journal":{"name":"Journal of Water Supply Research and Technology-aqua","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2023-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72686092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Tunnel water burst disaster management engineering based on artificial intelligence technology – taking Yonglian Tunnel in Jiangxi province as the object in China 基于人工智能技术的隧道突水灾害管理工程——以江西永联隧道为研究对象

IF 4.3

Journal of Water Supply Research and Technology-aqua Pub Date : 2023-07-12 DOI: 10.2166/ws.2023.170

Dan Li, Haowen Xu, Ting Jiang, Hong Ding, Yong Xiang

{"title":"Tunnel water burst disaster management engineering based on artificial intelligence technology – taking Yonglian Tunnel in Jiangxi province as the object in China","authors":"Dan Li, Haowen Xu, Ting Jiang, Hong Ding, Yong Xiang","doi":"10.2166/ws.2023.170","DOIUrl":"https://doi.org/10.2166/ws.2023.170","url":null,"abstract":"\u0000 Due to the influence of the groundwater system, mountain rock layers, climate rainfall, and tunnel length and depth, underground tunnel (UT) is prone to water inrush (WI) disasters, thus leading to delays and obstacles in construction projects. This article takes the Yonglian Tunnel as the research objective and explores the water and mud inrush disasters that occurred from July to August 2012. The Yonglian Tunnel is a control project of the Jilian Expressway in Jiangxi Province. This article aims to study and analyze the WI disaster management of UT using artificial intelligence technology, and to deepen the understanding of its causes. It will affect the factors, hazards, and related disaster management engineering methods of the Utah WI disaster. By establishing a back propagation neural network model and a radial basis function neural network model, the risk of WI disasters in tunnels, the degree of harm caused by WI, and the ability to control them were predicted and analyzed, and the stability and error values of the models were compared.","PeriodicalId":17553,"journal":{"name":"Journal of Water Supply Research and Technology-aqua","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2023-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80411410","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Improved RUSLE model to simulate the effect of slope forest area on soil and water conservation 改进RUSLE模型，模拟坡面林区水土保持效果

IF 4.3

Journal of Water Supply Research and Technology-aqua Pub Date : 2023-07-11 DOI: 10.2166/ws.2023.171

Hui Wang, Yu Bai, Xiaojun Man, Zhiping Tang, Shaoping Zhang

{"title":"Improved RUSLE model to simulate the effect of slope forest area on soil and water conservation","authors":"Hui Wang, Yu Bai, Xiaojun Man, Zhiping Tang, Shaoping Zhang","doi":"10.2166/ws.2023.171","DOIUrl":"https://doi.org/10.2166/ws.2023.171","url":null,"abstract":"\u0000 \u0000 The problem of soil and water loss on slope land has always been one of the key issues that people pay attention to. How to reasonably arrange tree species and planting methods can effectively improve the current situation of water loss and soil erosion. The Revised Universal Soil Loss Equation (RUSLE) model is a widely used soil erosion prediction model, but it does not consider the impact of tree height and crown size on soil erosion. In this paper, six experimental plots of soil and water conservation were carried out on the forest slope land in southern China. Six experimental plots were planted with different trees, and all kinds of data were collected for 3 years. On the basis of data analysis and machine learning methods, it is found that tree height and crown have a significant impact on soil erosion, but have no significant impact on runoff formation. With the growth of trees, the amount of soil loss in each plot gradually decreases. At the same time, an improved RUSLE model related to tree height and crown has been established, which has a high simulation effect (R2 of testing reaches 0.6775, R2 of all data reaches 0.5452).","PeriodicalId":17553,"journal":{"name":"Journal of Water Supply Research and Technology-aqua","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2023-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78578993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Application of data mining technology and intelligent information technology in the construction and management of the water conservancy project in Area A 数据挖掘技术与智能信息技术在A区水利工程建设与管理中的应用

IF 4.3

Journal of Water Supply Research and Technology-aqua Pub Date : 2023-07-11 DOI: 10.2166/ws.2023.169

Zeyou Chen, Jiaojiao Xu, Yunhui Ma, Zheyuan Zhang

{"title":"Application of data mining technology and intelligent information technology in the construction and management of the water conservancy project in Area A","authors":"Zeyou Chen, Jiaojiao Xu, Yunhui Ma, Zheyuan Zhang","doi":"10.2166/ws.2023.169","DOIUrl":"https://doi.org/10.2166/ws.2023.169","url":null,"abstract":"\u0000 A water conservancy project for the construction of foundation engineering is indispensable. Its development is very important to ensure the quality of the construction level and management and to ensure that the construction of water conservancy projects works in the direction of automation. The present water conservancy project construction and management is inefficient, hydrology prediction errors are prevalent, and the utilization rate of water resources is low. To address these issues, this paper will apply data mining technology and intelligent information technology in water conservancy project management. This helps to study better the construction and management of water conservancy projects. By employing data mining techniques, valuable data from water conservancy projects will be extracted and analyzed. The first step involves gathering the relevant data from the projects and subjecting it to data mining processes. Through careful analysis and evaluation of the data, we can predict the runoff in the reservoir hydrology of Area A. Experimental results demonstrate that utilizing data mining techniques to predict the runoff of Reservoir A from January to December 2020 yielded a difference of 3.44% between the maximum and minimum values. Furthermore, employing machine learning techniques for prediction resulted in a variation in the prediction error rate of 6.2%. The use of data mining technology can improve the efficiency of water conservancy project construction and management, and improve the utilization rate of the project.","PeriodicalId":17553,"journal":{"name":"Journal of Water Supply Research and Technology-aqua","volume":null,"pages":null},"PeriodicalIF":4.3,"publicationDate":"2023-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79181369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0