scholarly journals Abrupt Change Detection Method Based on Features of Lorenz Trajectories

Atmosphere ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 781
Author(s):  
Chaojiu Da ◽  
Binglu Shen ◽  
Jian Song ◽  
Cairang Xaiwu ◽  
Guolin Feng
Keyword(s):  
Time Series ◽  
Climate Changes ◽  
Abrupt Change ◽  
Atmospheric Model ◽  
Original Method ◽  
Lorenz Equation ◽  
Dynamical Characteristics ◽  
Abrupt Changes ◽  
The Times ◽  
The Right

This paper presents a definition of bifurcation-type abrupt changes based on the bifurcation features of Lorenz trajectories. These abrupt changes are the result of the transition behavior of dynamical system trajectories among different equilibrium regions. We demonstrate that these bifurcation-type jumps can better reflect the nature of abrupt change. In analyzing the features of Lorenz equation trajectories, a dynamical method for detecting bifurcation-type abrupt changes is presented. A numerical solution of the Lorenz equation is adopted, using a curve integral or vector product to construct a time series of positive and negative values. Changes in the sign of this time series accurately determine whether the trajectory is in the right or left equilibrium region, and the points at which the time series is equal to zero are the times at which the trajectory jumps between different equilibrium regions, that is, the occurrence times of bifurcation-type abrupt changes. This method is completely dependent on the dynamical characteristics of the system. A theoretical approach for detecting abrupt climate changes based on the dynamical characteristics of the atmospheric model is described. Compared with the original method of identifying abrupt climate changes, this method has dynamic significance and can detect abrupt changes in multi-dimensional time series. Although this method can be applied theoretically, applications to real atmospheric data first require the data to be smoothed.

Monitoring abrupt changes in satellite time series by seasonal confidence interval of regression residuals

2016 ◽  
Vol 14 (04) ◽  
pp. 1650022
Author(s):  
Zeng-Guang Zhou ◽  
Chang-Miao Hu ◽  
Ping Tang ◽  
Zheng Zhang
Keyword(s):  
Time Series ◽  
Confidence Interval ◽  
Regression Model ◽  
Seasonal Variability ◽  
Abrupt Change ◽  
Time Series Data ◽  
Series Data ◽  
Test Technique ◽  
Regression Residuals ◽  
Abrupt Changes

Near real-time monitoring of abrupt changes in satellite time series is important for timely warning of land covers changes. Regression model-based method has been frequently used to detect abrupt change (outlier or anomaly) in time series data. Abrupt change is often determined by residuals test after regression. A simple and widely used residuals test technique is confidence interval (CI), which is often time-independent or constant in many studies. However, satellite time series data is characterized by seasonal variability and periodicity. Although the periodicity could be fitted well by a seasonal-trend regression model, the seasonal variability still remains in the residuals of the regression model. The seasonal variability would lead to less reliable results if abrupt changes are detected by a constant confidence interval (CCI). In order to improve the reliability of abrupt change monitoring in satellite time series, in this paper we develop a criterion namely seasonal confidence interval (SCI) of regression residuals. Experimental evaluations with some simulated and actual satellite time series data demonstrate better performance of the proposed SCI criterion than the CCI criterion for monitoring abrupt changes in satellite time series.

scholarly journals Evaluation of Performance of Different Methods in Detecting Abrupt Climate Changes

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Chunyu Zhao ◽  
Yan Cui ◽  
Xiaoyu Zhou ◽  
Ying Wang
Keyword(s):  
Sample Size ◽  
Climate Changes ◽  
Abrupt Change ◽  
Surface Air Temperature ◽  
Dynamic Structure ◽  
Kendall Test ◽  
Evaluation Of Performance ◽  
Abrupt Changes ◽  
The Mean ◽  
Temperature Records

We compared and evaluated the performance of five methods for detecting abrupt climate changes using a time series with artificially generated abrupt characteristics. Next, we analyzed these methods using annual mean surface air temperature records from the Shenyang meteorological station. Our results show that the movingt-test (MTT), Yamamoto (YAMA), and LePage (LP) methods can correctly and effectively detect abrupt changes in means, trends, and dynamic structure; however, they cannot detect changes in variability. We note that the sample size of the subseries used in these tests can affect their results. When the sample size of the subseries ranges from one-quarter to three-quarters of the jump scale, these methods can effectively detect abrupt changes; they perform best when the sample size is one-half of the jump scale. The Cramer method can detect abrupt changes in the mean and trend of a series but not changes in variability or dynamic structure. Finally, we found that the Mann-Kendall test could not detect any type of abrupt change. We found no difference in the results of any of the methods following removal of the mean, creation of an anomaly series, or normalization. However, detrending and study period selection affected the results of the Cramer and Mann-Kendall methods; in the latter case, they could lead to a completely different result.

Ameloblastic Fibroma Associated With Impacted 3rd Molar: A Case Report

2017 ◽  
Vol 1 (7) ◽  
pp. 18-21
Author(s):  
K Indira Priyadarshini ◽  
Karthik Raghupathy ◽  
K V Lokesh ◽  
B Venu Naidu
Keyword(s):  
Relative Frequency ◽  
Posterior Region ◽  
Radiographic Examination ◽  
Dental Eruption ◽  
Ameloblastic Fibroma ◽  
Odontogenic Origin ◽  
The Common ◽  
The Times ◽  
The Right ◽  
Slow Growing

Ameloblastic fibroma is an uncommon mixed neoplasm of odontogenic origin with a relative frequency between 1.5 – 4.5%. It can occur either in the mandible or maxilla, but predominantly seen in the posterior region of the mandible. It occurs in the first two decades of life. Most of the times it is associated with tooth enclosure, causing a delay in eruption or altering the dental eruption sequence. The common clinical manifestation is a slow growing painless swelling and is detected during routine radiographic examination. There is controversy in the mode of treatment, whether conservative or aggressive. Here we reported a 38 year old male patient referred for evaluation of painless swelling on the right posterior region of the mandible associated with clinically missing 3rd molar. The lesion was completely enucleated under general anesthesia along with the extraction of impacted molar.

Agree to Disagree: Towards A Peaceful Co-Existence amongst Multi-Religious Community (Setuju untuk Tidak Bersetuju: Kearah Kehidupan Aman Ber-sama Dikalangan Masyarakat Berbilang Agama)

2017 ◽  
Vol 14 (1) ◽  
pp. 248-267
Author(s):  
Maulana Akbar Shah @ U Tun Aung ◽  
Mohammed Farid Ali ◽  
Muhammad Adil Khan Afridi
Keyword(s):  
Hard Work ◽  
Religious Community ◽  
Individual Choice ◽  
Human Race ◽  
Living Together ◽  
Peace And Security ◽  
The Times ◽  
The Right

Abstract Since the number of intricate problems with regard to peace and security faced by mankind on our sphere has been greater than what they can bear, the survival of human race on earth becomes a significant priority to be contemplated. Despite hard work and continued effort rendered by many experts, they face more serious issues and their resolutions are far from reality. It is because, in the author’s mind, rights and responsibilities are not properly observed. Particularly, in the area of religion people have lack of respecting the right of others and most of the times they are irresponsible. Every individual has their own choices according to their culture and belief which may not be acceptable to others. If every individual allows others to enjoy at their own choice while observing his own belief and tradition, we all can live in this world peacefully. This concept of living together with individual choice while respecting other’s choice may be called the concept of “agree to disagree” according to the author’s work. This ideology, which is yet to be well observed in our society, can surely replace violence with peaceful co-existence in the multi-religious and multi-cultural societies.   Keywords: Agree to Disagree, Mankind, Religious Dispute, Multi-Cultural Societies, peaceful Co-Existence. Abstrak Sejak masalah berkaitan dengan keharmonian dan keselamatan yang dialami manusia melebihi yang boleh ditanggung, kehidupan manusia di dunia ini menjadi satu keutamaan  yang perlu dipertimbangkan. Walaupun banyak usaha dan langkah diambil oleh pihak pakar, mereka mengalami masalah lain yang lebih serius dan resolusi mereka adalah jauh dari matlamat. Ini kerana, dalam minda pengarang, hak dan tanggungjawab tidak diperhatikan dengan betul. Terutamanya dalam hal agama, orang kekurangan kehormatan terhadap hak orang lain dan kebanyakkannya adalah tidak bertanggungjawab. Setiap individu mempunyai kepercayaan dan hak masing-masing yang tidak boleh diterima oleh yang lain. Jika setiap individu membenarkan yang lain untuk mempunyai kepercayaan dan hak masing-masing, manusia semua boleh hidup dengan aman. Konsep ini boleh dipanggil sebagai konsep “setuju untuk tidak bersetuju” menurut kajian pengarang. Ideologi ini, yang masih belum diperhatikan dengan sepenuhnya dalam masyarakat kita, pasti boleh menggantikan keganasan dengan kehidupan aman bersama dalam masyarakat berbilang kaum dan budaya. Kata Kunci: Setuju untuk Tidak Bersetuju, Manusia, Pertikaian Agama, Masyarakat Berbilang Agama, Kehidupan Aman Bersama.

A Machine Learning Application for Raising WASH Awareness in the Times of COVID-19 Pandemic (Preprint)

2020 ◽  
Author(s):  
Rohan Pandey ◽  
Vaibhav Gautam ◽  
Ridam Pal ◽  
Harsh Bandhey ◽  
Lovedeep Singh Dhingra ◽  
...  
Keyword(s):  
Machine Learning ◽  
Natural Language Processing ◽  
Natural Language ◽  
Machine Translation ◽  
Language Processing ◽  
User Feedback ◽  
Who Guidelines ◽  
The Times ◽  
The Right ◽  
Local Languages

BACKGROUND The COVID-19 pandemic has uncovered the potential of digital misinformation in shaping the health of nations. The deluge of unverified information that spreads faster than the epidemic itself is an unprecedented phenomenon that has put millions of lives in danger. Mitigating this ‘Infodemic’ requires strong health messaging systems that are engaging, vernacular, scalable, effective and continuously learn the new patterns of misinformation. OBJECTIVE We created WashKaro, a multi-pronged intervention for mitigating misinformation through conversational AI, machine translation and natural language processing. WashKaro provides the right information matched against WHO guidelines through AI, and delivers it in the right format in local languages. METHODS We theorize (i) an NLP based AI engine that could continuously incorporate user feedback to improve relevance of information, (ii) bite sized audio in the local language to improve penetrance in a country with skewed gender literacy ratios, and (iii) conversational but interactive AI engagement with users towards an increased health awareness in the community. RESULTS A total of 5026 people who downloaded the app during the study window, among those 1545 were active users. Our study shows that 3.4 times more females engaged with the App in Hindi as compared to males, the relevance of AI-filtered news content doubled within 45 days of continuous machine learning, and the prudence of integrated AI chatbot “Satya” increased thus proving the usefulness of an mHealth platform to mitigate health misinformation. CONCLUSIONS We conclude that a multi-pronged machine learning application delivering vernacular bite-sized audios and conversational AI is an effective approach to mitigate health misinformation. CLINICALTRIAL Not Applicable

Construct Validity

2017 ◽  
Author(s):  
Richard McCleary ◽  
David McDowall ◽  
Bradley J. Bartos
Keyword(s):  
Time Series ◽  
Construct Validity ◽  
Hypothesis Test ◽  
Secondary Data ◽  
Time Frame ◽  
Primary Data ◽  
Optimal Time ◽  
Intervention Model ◽  
Right Hand ◽  
The Right

Chapter 8 focuses on threats to construct validity arising from the left-hand side time series and the right-hand side intervention model. Construct validity is limited to questions of whether an observed effect can be generalized to alternative cause and effect measures. The “talking out” self-injurious behavior time series, shown in Chapter 5, are examples of primary data. Researchers often have no choice but to use secondary data that were collected by third parties for purposes unrelated to any hypothesis test. Even in those less-than-ideal instances, however, an optimal time series can be constructed by limiting the time frame and otherwise paying attention to regime changes. Threats to construct validity that arise from the right-hand side intervention model, such as fuzzy or unclear onset and responses, are controlled by paying close attention to the underlying theory. Even a minimal theory should specify the onset and duration of an impact.

scholarly journals Sensitivity Analysis of Sentinel-1 Backscatter to Oil Palm Plantations at Pluriannual Scale: A Case Study in Gabon, Africa

2021 ◽  
Vol 13 (11) ◽  
pp. 2075
Author(s):  
J. David Ballester-Berman ◽  
Maria Rastoll-Gimenez
Keyword(s):  
Time Series ◽  
Sensitivity Analysis ◽  
Oil Palm ◽  
Time Interval ◽  
Potential Candidate ◽  
Initial Growth ◽  
Natural Forests ◽  
Wet Season ◽  
Radar Signatures ◽  
The Times

The present paper focuses on a sensitivity analysis of Sentinel-1 backscattering signatures from oil palm canopies cultivated in Gabon, Africa. We employed one Sentinel-1 image per year during the 2015–2021 period creating two separated time series for both the wet and dry seasons. The first images were almost simultaneously acquired to the initial growth stage of oil palm plants. The VH and VV backscattering signatures were analysed in terms of their corresponding statistics for each date and compared to the ones corresponding to tropical forests. The times series for the wet season showed that, in a time interval of 2–3 years after oil palm plantation, the VV/VH ratio in oil palm parcels increases above the one for forests. Backscattering and VV/VH ratio time series for the dry season exhibit similar patterns as for the wet season but with a more stable behaviour. The separability of oil palm and forest classes was also quantitatively addressed by means of the Jeffries–Matusita distance, which seems to point to the C-band VV/VH ratio as a potential candidate for discrimination between oil palms and natural forests, although further analysis must still be carried out. In addition, issues related to the effect of the number of samples in this particular scenario were also analysed. Overall, the outcomes presented here can contribute to the understanding of the radar signatures from this scenario and to potentially improve the accuracy of mapping techniques for this type of ecosystems by using remote sensing. Nevertheless, further research is still to be done as no classification method was performed due to the lack of the required geocoded reference map. In particular, a statistical assessment of the radar signatures should be carried out to statistically characterise the observed trends.

scholarly journals The anatomy of past abrupt warmings recorded in Greenland ice

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
E. Capron ◽  
S. O. Rasmussen ◽  
T. J. Popp ◽  
T. Erhardt ◽  
H. Fischer ◽  
...  
Keyword(s):  
Climate Changes ◽  
Ice Core ◽  
Ice Cores ◽  
Climate System ◽  
Data Availability ◽  
Tight Coupling ◽  
Decadal Scale ◽  
Abrupt Changes ◽  
Systematic Pattern ◽  
The Last Glacial

AbstractData availability and temporal resolution make it challenging to unravel the anatomy (duration and temporal phasing) of the Last Glacial abrupt climate changes. Here, we address these limitations by investigating the anatomy of abrupt changes using sub-decadal-scale records from Greenland ice cores. We highlight the absence of a systematic pattern in the anatomy of abrupt changes as recorded in different ice parameters. This diversity in the sequence of changes seen in ice-core data is also observed in climate parameters derived from numerical simulations which exhibit self-sustained abrupt variability arising from internal atmosphere-ice-ocean interactions. Our analysis of two ice cores shows that the diversity of abrupt warming transitions represents variability inherent to the climate system and not archive-specific noise. Our results hint that during these abrupt events, it may not be possible to infer statistically-robust leads and lags between the different components of the climate system because of their tight coupling.

scholarly journals Spatial and Temporal Spread of the COVID-19 Pandemic Using Self Organizing Neural Networks and a Fuzzy Fractal Approach

2021 ◽  
Vol 13 (15) ◽  
pp. 8295
Author(s):  
Patricia Melin ◽  
Oscar Castillo
Keyword(s):  
Neural Networks ◽  
Time Series ◽  
Temporal Trends ◽  
Main Idea ◽  
Temporal Analysis ◽  
Virus Propagation ◽  
Self Organizing Maps ◽  
Fractal Approach ◽  
The Times ◽  
Self Organizing

In this article, the evolution in both space and time of the COVID-19 pandemic is studied by utilizing a neural network with a self-organizing nature for the spatial analysis of data, and a fuzzy fractal method for capturing the temporal trends of the time series of the countries considered in this study. Self-organizing neural networks possess the capability to cluster countries in the space domain based on their similar characteristics, with respect to their COVID-19 cases. This form enables the finding of countries that have a similar behavior, and thus can benefit from utilizing the same methods in fighting the virus propagation. In order to validate the approach, publicly available datasets of COVID-19 cases worldwide have been used. In addition, a fuzzy fractal approach is utilized for the temporal analysis of the time series of the countries considered in this study. Then, a hybrid combination, using fuzzy rules, of both the self-organizing maps and the fuzzy fractal approach is proposed for efficient coronavirus disease 2019 (COVID-19) forecasting of the countries. Relevant conclusions have emerged from this study that may be of great help in putting forward the best possible strategies in fighting the virus pandemic. Many of the existing works concerned with COVID-19 look at the problem mostly from a temporal viewpoint, which is of course relevant, but we strongly believe that the combination of both aspects of the problem is relevant for improving the forecasting ability. The main idea of this article is combining neural networks with a self-organizing nature for clustering countries with a high similarity and the fuzzy fractal approach for being able to forecast the times series. Simulation results of COVID-19 data from countries around the world show the ability of the proposed approach to first spatially cluster the countries and then to accurately predict in time the COVID-19 data for different countries with a fuzzy fractal approach.

Political Autobiography and the Art of the Plausible: R. A. Butler at the Foreign Office, 1938–1939

1985 ◽  
Vol 28 (4) ◽  
pp. 901-922 ◽  
Author(s):  
Paul Stafford
Keyword(s):  
Twentieth Century ◽  
Educational System ◽  
Spanish Civil War ◽  
British Politics ◽  
Suez Crisis ◽  
Foreign Office ◽  
Post War ◽  
The Times ◽  
The Right ◽  
Enoch Powell

R. A. Butler has been one of the outstanding figures in twentieth-century British politics. After his death The Times described him as ‘the creator of the modern educational system, the key-figure in the revival of post-war Conservatism, arguably the most successful chancellor since the war and un-questionably a Home Secretary of reforming zeal’. His record of achievement was unequalled by his rivals in the contests for the party leadership in 1957 and in 1963, but on both occasions the leadership eluded him. How and why this happened was understandably of the greatest interest to those who reviewed Rab's memoirs, The art of the possible, which were published in 1971. These memoirs won unanimous praise for their literary excellence, but otherwise met with a rather mixed reception. Enoch Powell, one of Rab's supporters in 1963, described them as ‘a work of astonishing self-revelation [belonging] with the classic Confessions. Augustine and Rousseau were not more unsparing of themselves than Rab…’ The ‘large episodes’ of Rab's career, Powell went on, ‘are treated with a generous vision (including, it need not be added, a generosity to Rab) which leaves the reader with improved understanding and perspective’. Powell's comments were echoed by others on the Right, but the Left was more critical. Anthony Howard noted that ‘what tend…to get wholly left out are the mistakes and blunders’ – the now infamous Villacoublay meeting during the Suez crisis; and Rab's astonishing admission to the journalist George Gale during the 1964 campaign that the election was slipping Labour's way. Harold Wilson, who had offered Rab the mastership of Trinity, was perhaps the least charitable of all. He found The art of the possible disappointing because, he claimed, Rab underwrote the great occasions. Rab's reticence about Suez, however, upset Wilson less than the description of his tribulations at the hands of Labour MPs as government spokesman for the policy of non-intervention during the Spanish Civil War. Here was an issue which could excite the older soldiers of the British Left, and if Wilson was alone among Rab's reviewers in making more than passing reference to Rab's association with appeasement this was why.

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