Droughts and aridity in northeast Brazil

ABSTRACT. Results of a study of droughts and aridity in northeast Brazil are presented in this paper. The study is based on the analysis of yearly water balances at fifteen stations in the region. Incidence of droughts of varying intensities at the stations is discussed. Climatic shifts at the stations are evaluated on the basis of the moisture index values. The use of the cumulative deviation technique in drought studies is briefly mentioned.

Cumulative deviation of a subpopulation from the full population

Assessing equity in treatment of a subpopulation often involves assigning numerical “scores” to all individuals in the full population such that similar individuals get similar scores; matching via propensity scores or appropriate covariates is common, for example. Given such scores, individuals with similar scores may or may not attain similar outcomes independent of the individuals’ memberships in the subpopulation. The traditional graphical methods for visualizing inequities are known as “reliability diagrams” or “calibrations plots,” which bin the scores into a partition of all possible values, and for each bin plot both the average outcomes for only individuals in the subpopulation as well as the average outcomes for all individuals; comparing the graph for the subpopulation with that for the full population gives some sense of how the averages for the subpopulation deviate from the averages for the full population. Unfortunately, real data sets contain only finitely many observations, limiting the usable resolution of the bins, and so the conventional methods can obscure important variations due to the binning. Fortunately, plotting cumulative deviation of the subpopulation from the full population as proposed in this paper sidesteps the problematic coarse binning. The cumulative plots encode subpopulation deviation directly as the slopes of secant lines for the graphs. Slope is easy to perceive even when the constant offsets of the secant lines are irrelevant. The cumulative approach avoids binning that smooths over deviations of the subpopulation from the full population. Such cumulative aggregation furnishes both high-resolution graphical methods and simple scalar summary statistics (analogous to those of Kuiper and of Kolmogorov and Smirnov used in statistical significance testing for comparing probability distributions).

Modern Trends in Variability of Climatic Characteristics in the Area of Makhachkala and Hydrological Consequences for the Turali Lakes

Within the limits of a century-long weakly positive trend of air temperature in the surface layer, periods of increased and decreased values of temperature, precipitation, air humidity, evaporation, water balance and moisture coefficient of the average for the year and individual seasons are highlighted. For this purpose, absolute and cumulative deviation values of characteristics are used. The results show, that the forecast of an acceleration of the rate of warming in the twenty-first century proved to be correct. The last cycle, which began in 2010-2012, is characterized by the most rapid increase in climate factors, that exacerbate the negative water balance in comparison with previous periods. This leads to the drying up of the Turaly lakes located on the southern side of the Makhachkala-Caspian agglomeration. The obtained results call into question the possibility and feasibility of using dry estuaries as water bodies for fish farming.

Change-Point Analysis of Precipitation and Drought Extremes in China over the Past 50 Years

Increases in climate extremes and their impacts have attracted global attention recently. In this study, the change-point years of precipitation extremes (PEs) and drought extremes (DEs) were investigated by Moving t-Test at 500 stations across the six regions in China. The detailed temporal change processes of them were demonstrated by the cumulative deviation method based on the data from nine typical stations. The results showed that: 1) DEs were more significantly and widely increased than PEs, the stations with increasing trends of PEs and DEs accounted for greater than 52.6% and 61.6% of the total, respectively; 2) increasing trends of DEs were mainly distributed in the east of Hu Huanyong Line. In this area, the increasing change-point years of DEs often occurred in the early 1980s in the south of the Yangzi River, while occurred in the 1990s in the north of the Yangzi River; 3) increasing trends of PEs were mainly distributed in Qing-Tibet Platen, Northwest China, and the southeastern area of Hu Huanyong Line. In these areas, the increasing change-point years of PEs often occurred around 1990 in the southeast of Hu Huanyong Line, while often occurred in the early 1980s in Qing-Tibet Platen. The results indicated that the area in the southeast of Hu Huanyong Line was under the threats of both PEs and DEs, this may produce severe impacts on agriculture, environment, water resources management, human society, etc.

Spatio-temporal variation of rainfall over Bihar State, India

This study detected, for the first time, the long term annual and seasonal rainfall trends over Bihar state, India, between 1901 and 2002. The shift change point was identified with the cumulative deviation test (cumulative sum – CUSUM), and linear regression. After the shift change point was detected, the time series was subdivided into two groups: before and after the change point. Arc-Map 10.3 was used to evaluate the spatial distribution of the trends. It was found that annual and monsoon rainfall trends decreased significantly; no significant trends were observed in pre-monsoon, monsoon, post-monsoon and winter rainfall. The average decline in rainfall rate was –2.17 mm·year−1and –2.13 mm·year−1for the annual and monsoon periods. The probable change point was 1956. The number of negative extreme events were higher in the later period (1957–2002) than the earlier period (1901–1956).

Evaluating the cumulative rainfall deviation approach for projecting groundwater levels under future climate

In south-western Australia (SWA) groundwater levels have been declining under the changing climate associated with a decline of rainfall. Possible future groundwater yields in SWA have been estimated under a range of climate change scenarios using a number of numerical groundwater models. For the Northern Perth Basin (NPB) in SWA, where no groundwater models were available, a relatively simple statistical method CDFM (Cumulative Deviation from Mean) has been applied using HARTT (Hydrograph Analysis and Rainfall Time Trends), an automated derivation of the CDFM. This study has evaluated the potential of the CDFM to project groundwater levels under various future climate scenarios in the NPB. Firstly, HARTT projections were validated by comparing with the modelled hydrographs in areas where numerical groundwater models were available. It was evident that HARTT may overestimate future declines or rises in groundwater levels depending on the time a new climate regime is imposed on the model. Secondly, HARTT was applied to suitable bores in the NPB under future climate scenarios. HARTT projected a slight decline under a drier future climate than under the historical future climate and a moderate or slight rise in groundwater levels under a wetter future climate. If historical climatic conditions continue until 2030, groundwater levels are expected to slightly rise in the NPB.

Research on Verfiable Design Model for Design Defect of Mechanical Assembly

Final assembly deviations of mechanical products are determined by accumulation, coupling and propagation of all parts tolerances in the assembly system, whether the final assembly meets the design specification or not can only be obtained after the assembly is completed. The verifiable design model in this paper took object-oriented Petri net as logic lever carrier, and embedded deviation in form of matrix to Petri net, and then analyzed and calculated the assembly deviation from the logical and numerical lever synchronically, after that the final cumulative deviation is obtained. If the cumulative deviation exceeded precision limit, key influence factors to the cumulative deviation could be analyzed. The assembly design defect is identified and located in the design process, and the synchronization of design and verification is achieved. This model has some excellent characteristics, such as modularization, reusability, and capability to describe structural logical relationships.

Fault Diagnosis of a Two Spool Turbo-Fan Engine Using Transient Data: A Genetic Algorithm Approach

Traditionally engine fault diagnosis has been performed at steady state conditions. There are several problems which can only be detected by transient data analysis like bearing fault, some control problems etc.. In addition, gas turbine performance deviation due to a component fault is more likely to be magnified during transients, when compared with the same parameter deviations at steady states. The specific approach used in this paper is to compare model-based information with measured data obtained from the engine during a slam acceleration. The measured transient data (from actual engine) is compared with a set of simulated data from the engine transient model, under similar operating conditions and known faults through a Cumulative Deviation. The Cumulative Deviations obtained from the comparisons are minimized for the best match using Genetic Algorithm. The Genetic Algorithm has been tailored to use real coding [1] method and to meet the requirements of the new procedure. The paper describes the application of the approach to a 2-spool turbofan engine and discusses the preliminary studies conducted.