scholarly journals Combining split-sample testing and hidden Markov modelling to assess the robustness of hydrological models

2021 ◽  
Vol 25 (8) ◽  
pp. 4611-4629
Author(s):  
Etienne Guilpart ◽  
Vahid Espanmanesh ◽  
Amaury Tilmant ◽  
François Anctil
Keyword(s):  
Hidden Markov ◽  
Land Use Changes ◽  
Hydrologic Model ◽  
Markov Modelling ◽  
Future Evolution ◽  
Considerable Uncertainty ◽  
Wide Range ◽  
Split Sample ◽  
The Future ◽  
Sample Testing

Abstract. The impacts of climate and land-use changes make the stationary assumption in hydrology obsolete. Moreover, there is still considerable uncertainty regarding the future evolution of the Earth’s climate and the extent of the alteration of flow regimes. Climate change impact assessment in the water sector typically involves a modelling chain in which a hydrological model is needed to generate hydrologic projections from climate forcings. Considering the inherent uncertainty of the future climate, it is crucial to assess the performance of the hydrologic model over a wide range of climates and their corresponding hydrologic conditions. In this paper, numerous, contrasted, climate sequences identified by a hidden Markov model (HMM) are used in a differential split-sample testing framework to assess the robustness of a hydrologic model. The differential split-sample test based on a HMM classification is implemented on the time series of monthly river discharges in the upper Senegal River basin in West Africa, a region characterized by the presence of low-frequency climate signals. A comparison with the results obtained using classical rupture tests shows that the diversity of hydrologic sequences identified using the HMM can help with assessing the robustness of the hydrologic model.

scholarly journals A Robust calibration/validation protocol of a hydrological model using hidden Markov states

2020 ◽  
Author(s):  
Etienne Guilpart ◽  
Vahid Espanmanesh ◽  
Amaury Tilmant ◽  
François Anctil
Keyword(s):  
Hidden Markov ◽  
Land Use Changes ◽  
Hydrologic Model ◽  
Climate Trend ◽  
Future Evolution ◽  
Considerable Uncertainty ◽  
Senegal River ◽  
Wide Range ◽  
Sample Test ◽  
Earth’S Climate

Abstract. The impacts of climate and land-use changes make the stationary assumption in hydrology obsolete. Moreover, there is still considerable uncertainty regarding the future evolution of the Earth's climate and the extent of the alteration of flow regimes. In that context, it is crucial to assess the performance of a hydrologic model over a wide range of climates and their corresponding hydrologic conditions. We propose a calibration/validation protocol based on the differential split-sample test and numerous, contrasted, climate sequences identified through a Hidden Markov Model (HMM) classification. The proposed protocol is tested on the Senegal River in West Africa. Results show that when the time series of river discharges does not exhibit a clear climate trend, or when it has multiple change points, classical rupture tests are useless and HMM classification is a viable alternative as long as the climate sub-sequences are long enough.

scholarly journals Detecting land use and climate impacts on water yield ecosystem service in arid and semi-arid areas. A study in Sirvan River Basin-Iran

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jahanbakhsh Balist ◽  
Bahram Malekmohammadi ◽  
Hamid Reza Jafari ◽  
Ahmad Nohegar ◽  
Davide Geneletti
Keyword(s):  
Land Use ◽  
River Basin ◽  
Ecosystem Service ◽  
Climatic Factors ◽  
Land Use Changes ◽  
Climate Impacts ◽  
Water Yield ◽  
Future Evolution ◽  
The Future ◽  
The Impact

AbstractThis study investigates how land use and climate changes affect water yield ecosystem service (ES) in the Sirvan River basin, located in Iran’s Kurdistan and Kermanshah provinces. By detecting land-use and climatic parameter changes in the past, their future evolution were modeled by scenario making. For this purpose, we developed two land-use scenarios (low and high urbanization) and two climatic scenarios (Representative Concentration Pathway 2.6 and RCP 8.5). The implemented scenarios showed how the amount of water yield in the basin and sub-basins changes in the future based on climate and land-use changes. The results showed that, concerning land use, the forest has decreased from 2013 to 2019, and built-up areas have increased. Also, the results showed that precipitation has been declining in the long term, and the temperature has been rising. Finally, the Water yield in 2019 was higher than in 2013 and lower in the future based on forecast scenarios. This trend will continue until 2040. In addition, it was found that the t effects of these factors on water yield ES are a complex process, and based on the results, the impact of climatic factors is more significant than the one of land-use change. We could conclude that this region will face more environmental problems in the future.

Features of optative modality in Macedonian language (with emphasis on the functionalities of independent da-construction)

2020 ◽  
pp. 301-323
Author(s):  
Natalya I. Kikilo ◽  
Keyword(s):  
Detailed Analysis ◽  
Present Article ◽  
Literary Language ◽  
Natural Context ◽  
Wide Range ◽  
Verb Forms ◽  
Text Types ◽  
The Future ◽  
The Subject ◽  
Ritual Context

In the Macedonian literary language the analytic da-construction used in an independent clause has a wide range of possible modal meanings, the most common of which are imperative and optative. The present article offers a detailed analysis of the semantics and functions of the Macedonian optative da-construction based on fiction and journalistic texts. The first part of the article deals with the specificities of the optative as a category which primarily considers the subject of a wish. In accordance with the semantic characteristics of this category, optative constructions are used in those discourse text types where the speakers are explicitly designated (the most natural context for the optative is the dialogue). The analysis of the Macedonian material includes instances of atypical usage of the optative da-construction, in which the wish of the subject is not apparent and thereby produces new emotional tonalities perceptible to the reader of a fiction/journalistic text. The study describes Macedonian constructions involving two different verb forms: 1) present tense form (da + praes) and 2) imperfective form (da + impf). These constructions formally designate the hypothetical and counterfactual status of the optative situation, respectively. Thus, the examples in the analysis are ordered according to two types of constructions, which reflect the speaker’s view on the probability of the realisation of his/her wish. Unrealistic wishes can be communicated through the present da-construction, while the imperfective construction denotes situations in which the wish can be realised in the future. The second part of the article is devoted to performative optative da-constructions, which express formulas of speech etiquette, wishes and curses. The analysis demonstrates that these constructions lose their magical functions, when used outside of the ritual context, and begin to function as interjections.

On the identity of socialism in modern China

2019 ◽  
pp. 75-89
Author(s):  
A.B. Lyubinin
Keyword(s):  
Economic System ◽  
Modern China ◽  
Soviet Society ◽  
Chinese Society ◽  
Transitional Form ◽  
Global Development ◽  
Future Evolution ◽  
The Future ◽  
Marxist Concept

The article comments on the concept of «socialism with Chinese specificity», which forms the ideological basis of the «Chinese miracle». The ideological origins of this concept, starting with Confucianism, are revealed. It has evolved to become increasingly pragmatic and to adapt to the realities of national and global development. The relation of this concept with the Marxist concept of socialism is shown. The article substantiates the fundamental theoretical thesis that in the objective-essential sense (in the elimination of, in particular, national specifics) Chinese society is a transitional form to socialism (a certain analogue of the Soviet society of the NEP period). The author talks about a «heterogeneous», «mixed» socio-economic system, the vector and nature of the future evolution of which will depend crucially on the strategic course of the CPC.

Key directions and methodological features of modern studies of land use changes

2019 ◽  
pp. 62-68
Author(s):  
Pavlo Kazmir ◽  
Lyubomyr Kazmir
Keyword(s):  
Land Use ◽  
Land Use Changes ◽  
Scientific Discipline ◽  
Shared Responsibility ◽  
Management Tools ◽  
Land Change Science ◽  
Wide Range ◽  
Land Relations ◽  
Future Policy ◽  
Planning Methodology

Interest in land-use changes (LUC) research has been growing rapidly in recent years. This topic has already become the subject of a separate scientific discipline – land use science (or land change science). In order to formulate relevant future policy and develop appropriate land-use management tools, it is crucial to know how the LUC шьзфсе the environment and society condition. For Ukraine, where the structure of land use and the system of land resources management have significantly changed during the years of post-socialist transformation of land relations, the study of the LUC on a modern methodological basis is especially actual. The paper, based on a critical analysis of publications in leading international journals over the last thirty years, identifies key directions of LUC studies and analyzes their methodological features. There is a significant increase of the number of works based on the results of meta-studies and the use of a wide range of methods for modeling the LUC processes, their causes and possible consequences. The great "synergistic potential" of integration of the selected directions is noted, which makes it possible to accelerate the development of the general theory of land use and increase its use efficiency in substantiation of management decisions in the sphere of land use and modernization of the mechanisms of state land, spatial and ecological policies with consideration of existing and potential globalizing challenges. In this context, the key role of the land use integrated planning methodology at regional and local levels is emphasized. This methodology would require close cooperation between government, business and the public in developing a common vision for the implementation of specific land use plans and projects based on the principles of subsidiarity, participativity and shared responsibility.

scholarly journals Frequency Division Multiplexing of Terahertz Waves Realized by Diffractive Optical Elements

2021 ◽  
Vol 11 (14) ◽  
pp. 6246
Author(s):  
Paweł Komorowski ◽  
Patrycja Czerwińska ◽  
Mateusz Kaluza ◽  
Mateusz Surma ◽  
Przemysław Zagrajek ◽  
...  
Keyword(s):  
Frequency Division Multiplexing ◽  
Diffractive Optical Elements ◽  
Frequency Division ◽  
Terahertz Waves ◽  
Optical Elements ◽  
Telecommunication Systems ◽  
Wide Range ◽  
The Future ◽  
Wireless Telecommunication ◽  
Finite Distance

Recently, one of the most commonly discussed applications of terahertz radiation is wireless telecommunication. It is believed that the future 6G systems will utilize this frequency range. Although the exact technology of future telecommunication systems is not yet known, it is certain that methods for increasing their bandwidth should be investigated in advance. In this paper, we present the diffractive optical elements for the frequency division multiplexing of terahertz waves. The structures have been designed as a combination of a binary phase grating and a converging diffractive lens. The grating allows for differentiating the frequencies, while the lens assures separation and focusing at the finite distance. Designed structures have been manufactured from polyamide PA12 using the SLS 3D printer and verified experimentally. Simulations and experimental results are shown for different focal lengths. Moreover, parallel data transmission is shown for two channels of different carrier frequencies propagating in the same optical path. The designed structure allowed for detecting both signals independently without observable crosstalk. The proposed diffractive elements can work in a wide range of terahertz and sub-terahertz frequencies, depending on the design assumptions. Therefore, they can be considered as an appealing solution, regardless of the band finally used by the future telecommunication systems.

Digital Authoritarianism and the Future of Human Rights

2021 ◽  
pp. 1-27
Author(s):  
Tiberiu Dragu ◽  
Yonatan Lupu
Keyword(s):  
Human Rights ◽  
New Technologies ◽  
Theoretic Model ◽  
Human Rights Abuses ◽  
Human Rights Regime ◽  
Wide Range ◽  
The Future ◽  
Technological Developments ◽  
Game Theoretic ◽  
Strategic Context

Abstract How will advances in digital technology affect the future of human rights and authoritarian rule? Media figures, public intellectuals, and scholars have debated this relationship for decades, with some arguing that new technologies facilitate mobilization against the state and others countering that the same technologies allow authoritarians to strengthen their grip on power. We address this issue by analyzing the first game-theoretic model that accounts for the dual effects of technology within the strategic context of preventive repression. Our game-theoretical analysis suggests that technological developments may not be detrimental to authoritarian control and may, in fact, strengthen authoritarian control by facilitating a wide range of human rights abuses. We show that technological innovation leads to greater levels of abuses to prevent opposition groups from mobilizing and increases the likelihood that authoritarians will succeed in preventing such mobilization. These results have broad implications for the human rights regime, democratization efforts, and the interpretation of recent declines in violent human rights abuses.

Report on CLEF 2019

2019 ◽  
Vol 53 (2) ◽  
pp. 108-118
Author(s):  
Martin Braschler ◽  
Linda Cappellato ◽  
Fabio Crestani ◽  
Nicola Ferro ◽  
Gundula Heinatz Bürki ◽  
...  
Keyword(s):  
Standard Test ◽  
Future Perspectives ◽  
Research Papers ◽  
Test Collections ◽  
Lessons Learnt ◽  
Wide Range ◽  
The Future ◽  
20Th Anniversary

This is a report on the tenth edition of the Conference and Labs of the Evaluation Forum (CLEF 2019), held from September 9--12, 2019, in Lugano, Switzerland. CLEF was a four day event combining a Conference and an Evaluation Forum. The Conference featured keynotes by Bruce Croft, Yair Neuman, and Miguel Martínez, and presentation of peer reviewed research papers covering a wide range of topics in addition to many posters. The Evaluation Forum consisted to nine Labs: CENTRE, CheckThat, eHealth, eRisk, ImageCLEF, LifeCLEF, PAN, PIR-CLEF, and ProtestNews, addressing a wide range of tasks, media, languages, and ways to go beyond standard test collections. CLEF 2019 marked the 20th anniversary of CLEF, which was celebrated with a dedicated session and a book on the lessons learnt in twenty years of evaluation activities and the future perspectives for CLEF. CLEF 2019 also introduced the Industry Days to further extend the reach and impact of CLEF.

scholarly journals Simulating Land-Use Changes and Predicting Maize Potential Yields in Northeast China for 2050

2021 ◽  
Vol 18 (3) ◽  
pp. 938
Author(s):  
Luoman Pu ◽  
Jiuchun Yang ◽  
Lingxue Yu ◽  
Changsheng Xiong ◽  
Fengqin Yan ◽  
...  
Keyword(s):  
Land Use ◽  
Food Security ◽  
Northeast China ◽  
Land Use Changes ◽  
Sanjiang Plain ◽  
Potential Production ◽  
Potential Yield ◽  
The Sanjiang Plain ◽  
Ecological Zones ◽  
The Future

Crop potential yields in cropland are the essential reflection of the utilization of cropland resources. The changes of the quantity, quality, and spatial distribution of cropland will directly affect the crop potential yields, so it is very crucial to simulate future cropland distribution and predict crop potential yields to ensure the future food security. In the present study, the Cellular Automata (CA)-Markov model was employed to simulate land-use changes in Northeast China during 2015–2050. Then, the Global Agro-ecological Zones (GAEZ) model was used to predict maize potential yields in Northeast China in 2050, and the spatio-temporal changes of maize potential yields during 2015–2050 were explored. The results were the following. (1) The woodland and grassland decreased by 5.13 million ha and 1.74 million ha respectively in Northeast China from 2015 to 2050, which were mainly converted into unused land. Most of the dryland was converted to paddy field and built-up land. (2) In 2050, the total maize potential production and average potential yield in Northeast China were 218.09 million tonnes and 6880.59 kg/ha. Thirteen prefecture-level cities had maize potential production of more than 7 million tonnes, and 11 cities had maize potential yields of more than 8000 kg/ha. (3) During 2015–2050, the total maize potential production and average yield decreased by around 23 million tonnes and 700 kg/ha in Northeast China, respectively. (4) The maize potential production increased in 15 cities located in the plain areas over the 35 years. The potential yields increased in only nine cities, which were mainly located in the Sanjiang Plain and the southeastern regions. The results highlight the importance of coping with the future land-use changes actively, maintaining the balance of farmland occupation and compensation, improving the cropland quality, and ensuring food security in Northeast China.

scholarly journals Are we observing an NSC in course of formation in the NGC 4654 galaxy?

2021 ◽  
Vol 503 (1) ◽  
pp. 594-602
Author(s):  
R Schiavi ◽  
R Capuzzo-Dolcetta ◽  
I Y Georgiev ◽  
M Arca-Sedda ◽  
A Mastrobuono-Battisti
Keyword(s):  
Central Zone ◽  
Effective Radius ◽  
Host Galaxy ◽  
Galactic Centre ◽  
Future Evolution ◽  
Orbital Parameters ◽  
Relative Orbit ◽  
The Future ◽  
The Galaxy ◽  
Massive Clusters

ABSTRACT We use direct N-body simulations to explore some possible scenarios for the future evolution of two massive clusters observed towards the centre of NGC 4654, a spiral galaxy with mass similar to that of the Milky Way. Using archival HST data, we obtain the photometric masses of the two clusters, M = 3 × 105 M⊙ and M = 1.7 × 106 M⊙, their half-light radii, Reff ∼ 4 pc and Reff ∼ 6 pc, and their projected distances from the photometric centre of the galaxy (both <22 pc). The knowledge of the structure and separation of these two clusters (∼24 pc) provides a unique view for studying the dynamics of a galactic central zone hosting massive clusters. Varying some of the unknown cluster orbital parameters, we carry out several N-body simulations showing that the future evolution of these clusters will inevitably result in their merger. We find that, mainly depending on the shape of their relative orbit, they will merge into the galactic centre in less than 82 Myr. In addition to the tidal interaction, a proper consideration of the dynamical friction braking would shorten the merging times up to few Myr. We also investigate the possibility to form a massive nuclear star cluster (NSC) in the centre of the galaxy by this process. Our analysis suggests that for low-eccentricity orbits, and relatively long merger times, the final merged cluster is spherical in shape, with an effective radius of few parsecs and a mass within the effective radius of the order of $10^5\, \mathrm{M_{\odot }}$. Because the central density of such a cluster is higher than that of the host galaxy, it is likely that this merger remnant could be the likely embryo of a future NSC.

Sign in / Sign up

Export Citation Format

Share Document