Assessing the effects of non-stationarity on reservoir yield estimations: A case study of the Southern Okavango Integrated Water Development system in Botswana

Streamflow data used for water resources planning should ideally be stationary, and any non-stationary behaviour is taken into account. However, with limited time series data, the influence of non-stationarity is often hidden and can result in unreliable estimates. This paper examines the impact of non-stationarity on the Southern Okavango Integrated Water Development (SOIWD) project that was carried out with streamflow collected between 1969 and 1989 against an extended time series from 1990 to 2019. To achieve this, (a) the statistics of these inflows and (b) the reliability of satisfying water demands from the proposed reservoirs were tested based on the two periods (1969–1989 and 1990–2019). The results show that average monthly flows for July, August and September significantly change when peak outflows from the delta occur. Given the expected variability of the flow regime, an uncertainty approach utilising flow perturbation from ±5% to ±90% was also used to investigate the system's response to changes in the driving flow conditions. The increasing availability of flow data from 1990 to 2019 has shown that the SOIWD system would not have satisfied the water demand as it would not be operationally viable. This confirms the importance of accounting for non-stationarity in reservoir yield estimation and reemphasises its importance in hydrological studies.     

Investigation of nanoyarn preparation by modified electrospinning setup

Higher ordered structures of nanofibers, including nanofiber‐based yarns and cables, have a variety of potential applications, including wearable health monitoring systems, artificial tendons, and medical sutures. In this study, twisted assemblies of polyacrylonitrile (PAN), polyvinylidene fluoride trifluoroethylene (PVDF‐TrFe), and polycaprolactone (PCL) nanofibers were fabricated via a modified electrospinning setup, consisting of a rotating cone‐shaped copper collector, two syringe pumps, and two high voltage power supplies. The fiber diameters and twist angles varied as a function of the rotary speed of the collector. Mechanical testing of the yarns revealed that PVDF‐TrFe and PCL yarns have a higher strain‐to‐failure than PAN yarns, reaching 307% for PCL nanoyarns. For the first time, the porosity of nanofiber yarns was studied as a function of twist angle, showing that PAN nanoyarns are more porous than PCL yarns. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44813.     

A study of the temperature sensitivity of GaAs-(Al,Ga)As multiplequantum-well GRINSCH lasers

We have measured the temperature sensitivity, T₀, of GaAs-(Al,Ga)As, GRINSCH, multiple quantum-well (MQW) lasers with different numbers of quantum wells ranging from one to ten. Our data suggests that there is an optimum number of wells, namely five, where T ₀ is highest. Using a temperature-dependent model based on drift-diffusion equations, we have systematically analyzed the temperature sensitivity of a MQW GaAs-(Al, Ga)As laser. The T₀ versus well-number behavior observed experimentally is verified, and the important temperature-dependent factors are identified     

Application of artificial neural networks in the geographical identification of coffee samples

The recognition of the characteristics of coffee associated with a given agricultural system and aimed at adding value and attending the consumers’ demands stimulates the production of types of coffee properly described. The objective of this study was to explore and to explain the physicochemical characteristics and sensory attributes of the coffee grown in Parana State (Southern Brazil) based on an integrated approach of the terrior and the application of artificial neural network. Physicochemical variables of green coffee beans and roasted coffee beans were determined, as well as sensory attributes of the beverage. One hundred and seventy-two coffee samples were analyzed for moisture, proteins, chlorogenic acids, tannins, total acidity, total lipids, caffeine, total and reducing sugars and minerals. These properties were tabulated and presented to artificial neural network multilayer perceptron to be identified as the region and the city of planting. The artificial neural network classified correctly and tested 100% of the samples grown by region. For the database containing information by city, the automatic mode of the software Statistica 9.0 was used. The neural network showed 99% accuracy in training and 100% accuracy in the stage of testing and validation.     

A robust auto‐adaptive approach for serial acquisition of generalized multi‐carrier spread spectrum in multipath fading mobile channels

In this paper, a new robust auto‐adaptive approach for pseudo‐noise (PN) code acquisition is proposed. It is applied to the generalized multi‐carrier direct‐sequence code‐division multiple‐access (MC DS‐CDMA) systems communicating over frequency‐selective multipath Rayleigh fading channels. This new approach is based on the constant false alarm rate (CFAR) detection algorithm, referred here as automatic selection partial sum ordered statistics (ASPSOS)‐CFAR. The proposed approach does not require any prior information about the background environment and uses maximum likelihood estimation (MLE) method to detect the interfering signals group in the ranked cells for the full reference window. Once this group is identified and censored, the remaining smaller ranked cells are combined to form an estimate of the background noise level to compute the adaptive threshold. Through simulations, the performance of the proposed detector is analyzed and compared with traditional CFAR detectors based on fixed or automatic censoring algorithms. The obtained results show that the proposed detector eliminates the drawbacks of the previously related detectors and offers a robust detection performance to enhance the acquisition process in heterogeneous background environments.     

Improved understanding of metal ion reservoirs within barrier-metal systems

Within integrated circuits there are many instances where low current density lines feed directly (without a via) into a single line of much higher current density, for example with clock or power supply distribution. This work demonstrates and discusses increased lifetime with increasing numbers of current feed lines in a barrier metal interconnect system. The low current density feed lines (branches) act as reservoirs or sources of additional Al and Cu ions, which can re-fill portions of voids and/or slow void growth in the high current density line (trunk). It is discussed that any area of metal at a lower current density might be considered a reservoir or source of metal ions for higher current density regions, and can effectively extend the lifetime of the higher current density region. Narrow lines may get more benefit than wide lines. Increasing reservoir size will increase lifetime, within limits.     

Choosing communication portfolios to accomplish tasks: The effects of individual differences

The myriad of information communication technologies (ICTs) available today has changed the way students choose and use them. Specifically, individuals are increasingly relying on a mix of ICTs for communication to accomplish tasks. Yet, past studies on ICT use has largely assumed that people use a single ICT per task. We attempt to address this gap by focusing on the influence of individual differences on the choice of communication portfolio (a mix of ICTs) to accomplish learning tasks in school-based settings. Specifically, we focus on two dimensions of individual differences: learning styles and individuals’ perceptions. Results suggest that individual differences do have effects on the choice of communication portfolios to accomplish tasks. In particular, we found that students who preferred to learn by hearing tended to choose the complex communication portfolio to accomplish their tasks. Interestingly, our results also indicate that students preferred to use the simple communication portfolio when communication partners were perceived to be unavailable.     

Influence du processus de coping de l’enfant d’age scolaire sur son adaptation à la séparation parentale et aux conflits entre ses parents.

There exists an abundant literature on the effects of parental separation on children. However, few studies focus on the coping process employed by children to help them deal with this familial restructuring. Eighty-five children and their parents, from intact or separated families, answered questionnaires measuring parental conflicts, the child’s coping process, and the child’s adaptation to validate a theoretical model of child adaptation and to identify the mechanisms by which this process is related to their adaptation. The model takes into account the coping process of children subjected to family-related stress. Path analyses show that threat appraisal influences the choice of coping strategies, and reveal that active strategies influence the perceived efficacy of the coping strategies. The results also show that the children’s coping process is partially tied to their adaptation in various ways. However, avoidance and support seeking coping strategies could have different impacts on the adaptation of the children of each group. This study also draws attention to the direct impact of conjugal conflicts on the child’s adaptation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)