Burst Detection by Water Demand Nowcasting Based on Exogenous Sensors

Bursts of drinking water pipes not only cause loss of drinking water, but also damage below and above ground infrastructure. Short-term water demand forecasting is a valuable tool in burst detection, as deviations between the forecast and actual water demand may indicate a new burst. Many of burst detection methods struggle with false positives due to non-seasonal water consumption as a result of e.g. environmental, economic or demographic exogenous influences, such as weather, holidays, festivities or pandemics. Finding a robust alternative that reduces the false positive rate of burst detection and does not rely on data from exogenous processes is essential. We present such a burst detection method, based on Bayesian ridge regression and Random Sample Consensus. Our exogenous nowcasting method relies on signals of all nearby flow and pressure sensors in the distribution net with the aim to reduce the false positive rate. The method requires neither data of exogenous processes, nor extensive historical data, but only requires one week of historical data per flow/pressure sensor. The exogenous nowcasting method is compared with a common water demand forecasting method for burst detection and shows sufficiently higher Nash-Sutcliffe model efficiencies of 82.7% - 90.6% compared to 57.9% - 77.7%, respectively. These efficiency ranges indicate a more accurate water demand prediction, resulting in more precise burst detection.

     

Food security problems in sub-Saharan Africa: Operations Research as a tool of analysis

For many years, the author has been involved in teaching and research in the use of Operations Research as a tool of analysis to study food security problems in sub‐Saharan Africa, in particular, grass root problems of poor farmers. The paper presents an introduction to the way Operations Research methods have been applied in case studies and research projects, and discusses in retrospect the author's views on the strengths and limitations of the application of Operations Research. The paper has in particular been written for people who are not familiar with applications of Operations Research in agriculture, and are interested to learn about its potential usefulness in practice. The retrospective part is largely based on food security studies in e.g. Tanzania, Burkina Faso, Bénin, Togo and Eritrea and on participation in several interdisciplinary research programmes in Africa.     

In situ laser heating and radial synchrotron x-ray diffraction in a diamond anvil cell

We report a first combination of diamond anvil cell radial x-ray diffraction with in situ laser heating. The laser-heating setup of ALS beamline 12.2.2 was modified to allow one-sided heating of a sample in a diamond anvil cell with an 80 W yttrium lithium fluoride laser while probing the sample with radial x-ray diffraction. The diamond anvil cell is placed with its compressional axis vertical, and perpendicular to the beam. The laser beam is focused onto the sample from the top while the sample is probed with hard x-rays through an x-ray transparent boron-epoxy gasket. The temperature response of preferred orientation of (Fe,Mg)O is probed as a test experiment. Recrystallization was observed above 1500 K, accompanied by a decrease in stress.     

Characterizing the nano and micro structure of concrete to improve its durability

New and advanced methodologies have been developed to characterize the nano and microstructure of cement paste and concrete exposed to aggressive environments. High resolution full-field soft X-ray imaging in the water window is providing new insight on the nano scale of the cement hydration process, which leads to a nano-optimization of cement-based systems. Hard X-ray microtomography images of ice inside cement paste and cracking caused by the alkali–silica reaction (ASR) enables three-dimensional structural identification. The potential of neutron diffraction to determine reactive aggregates by measuring their residual strains and preferred orientation is studied. Results of experiments using these tools are shown on this paper.     

Similarities and differences in four views of David.

In this article, each author gives a brief comment on similarities he or she sees throughout the case formulations captured in the articles by Watson (2010a), Silberschatz (2010), Goldfried (2010), and Caspar (2010). A systematic comparison is added. Overall, the impression is confirmed and maintained that if authors are ready to renounce the use of the jargon of their specific approach, many similarities can be found. There are nevertheless differences that would lead us to expect a different course of therapy and different effects beyond the main effect of recovery in the case of David, pursuing the conceptualization and interventions proposed by Watson (2010b). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evaluation of the safety assurance level for Salmonella spp. throughout the food production chain in Switzerland

In Switzerland. the safeguarding of food is the responsibility of industry, organizations, and governmental authorities. The dispersion of the tasks and the diversity of implemented safety measures among involved stakeholders do not allow a general overview of the national safety assurance level provided. A comprehensive evaluation of the level of safety assurance provided for foodborne pathogens such as Salmonella spp. is therefore lacking, and the prevalence of Salmonella spp. at various points in the food production chain is not known. The objectives of this study were to (i) collect data on safety measures implemented throughout the food production chain in Switzerland regarding Salmonella spp.; (ii) evaluate the safety assurance level for Salmonella spp. at each step of the production chain for chicken meat, pork, beef, and milk and dairy products (bovine origin); and (iii) gather data on the prevalence of the pathogen at each step. Data on implemented safety assurance measures for Salmonella spp. were gathered from the various stakeholders in the food production chain. The data were analyzed by a semiquantitative method that considered the quality and relevance of the implemented safety measures for Salmonella spp. The safety assurance level for Salmonella spp. was evaluated from "no safety assurance" to "very good safety assurance." Available results of testing for Salmonella spp. from 1998 to 2000 were used for calculating the prevalence of the pathogen throughout the food production chain. The results showed a varying safety assurance level for Salmonella spp. throughout the food production chain. Strengths (e.g., feed production for chickens) and weaknesses (e.g., pork production) were observed. These results serve as a basis for a rational optimization of the system.     

Acoustic emission (AE) measurements to determine the dynamic flying characteristics of optical sliders

Flying heads carrying a magnetic coil and a high numerical aperture lens for magneto-optic recording or a solid immersion lens for optical phase change recording, respectively, are promising approaches for increasing the data density. A classic approach to dynamically evaluate the flight attitude of flying heads in data storage is acoustic emission (AE) testing of the head/disk interaction using special glide heads. In our paper we introduce the application of AE test heads for measuring the flying characteristics of optical far field and near field sliders. In comparison to conventional external AE sensors, i.e. sensors mounted somewhere in the drive, these AE elements are directly mounted on the sliders thus yielding a higher pulse shape and a better signal to noise ratio. This set-up allows a clear identification of the head disk contact. To calibrate the sensor a bump disk was fabricated and used for AE measurements.