Data Analysis and Performance Evaluation of Japanese Dual-sensor Systems Tested in Croatia

Two years ago, the Croatian Mine Action Center–Center for Testing Development and Training Ltd. tested two Japanese dual-sensor systems for humanitarian demining in Croatia. The test’s results show that these detection systems can potentially increase the accuracy of mine-detecting operations, but several improvements to the sensors may be required before the systems are fully effective

Air-Coupled Ultrasonic Ferroelectret Receiver with Additional DC Voltage

Highly sensitive air-coupled ultrasonic sensors are essential for various applications such as testing of composite materials. One of the major challenges for the development of air-coupled ultrasonic sensors is the impedance matching to air. With a lower acoustic impedance than the usual piezoelectric materials, charged cellular polypropylene film (cPP) offers better matching to air with a similar piezoelectric coefficient. The piezoelectric behaviour demonstrated by cPP comes from polarized air cells that create a permanent internal voltage. The sensitivity of the sensor varies with the application of an additional DC bias voltage. Thus, this work presents a cPP ultrasonic sensor with an improvement of up to 15 ± 1 dB on the signal-to-noise ratio

ITEP Test Trials for Detection Reliability Assessment of Metal Detectors

The total detection reliability of a mine-searching system is governed by the following three elements: Intrinsic capability, which describes the basic physical-technical capability of the method. Application factors, which include those due to environment. Human factor, which is the effect of human operators on the detection reliability. Some of these can be determined in simple laboratory measurements in which the effect on detection capability of individual parameters is measured. However, the human factor and some aspects of the effects of environmental conditions on the system need to be treated statistically

Global age-sex-specific mortality, life expectancy, and population estimates in 204 countries and territories and 811 subnational locations, 1950–2021, and the impact of the COVID-19 pandemic: a comprehensive demographic analysis for the Global Burden of Disease Study 2021

Background Estimates of demographic metrics are crucial to assess levels and trends of population health outcomes. The profound impact of the COVID-19 pandemic on populations worldwide has underscored the need for timely estimates to understand this unprecedented event within the context of long-term population health trends. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 provides new demographic estimates for 204 countries and territories and 811 additional subnational locations from 1950 to 2021, with a particular emphasis on changes in mortality and life expectancy that occurred during the 2020–21 COVID-19 pandemic period. Methods 22 223 data sources from vital registration, sample registration, surveys, censuses, and other sources were used to estimate mortality, with a subset of these sources used exclusively to estimate excess mortality due to the COVID-19 pandemic. 2026 data sources were used for population estimation. Additional sources were used to estimate migration; the effects of the HIV epidemic; and demographic discontinuities due to conflicts, famines, natural disasters, and pandemics, which are used as inputs for estimating mortality and population. Spatiotemporal Gaussian process regression (ST-GPR) was used to generate under-5 mortality rates, which synthesised 30 763 location-years of vital registration and sample registration data, 1365 surveys and censuses, and 80 other sources. ST-GPR was also used to estimate adult mortality (between ages 15 and 59 years) based on information from 31 642 location-years of vital registration and sample registration data, 355 surveys and censuses, and 24 other sources. Estimates of child and adult mortality rates were then used to generate life tables with a relational model life table system. For countries with large HIV epidemics, life tables were adjusted using independent estimates of HIV-specific mortality generated via an epidemiological analysis of HIV prevalence surveys, antenatal clinic serosurveillance, and other data sources. Excess mortality due to the COVID-19 pandemic in 2020 and 2021 was determined by subtracting observed all-cause mortality (adjusted for late registration and mortality anomalies) from the mortality expected in the absence of the pandemic. Expected mortality was calculated based on historical trends using an ensemble of models. In location-years where all-cause mortality data were unavailable, we estimated excess mortality rates using a regression model with covariates pertaining to the pandemic. Population size was computed using a Bayesian hierarchical cohort component model. Life expectancy was calculated using age-specific mortality rates and standard demographic methods. Uncertainty intervals (UIs) were calculated for every metric using the 25th and 975th ordered values from a 1000-draw posterior distribution. Findings Global all-cause mortality followed two distinct patterns over the study period: age-standardised mortality rates declined between 1950 and 2019 (a 62·8% [95% UI 60·5–65·1] decline), and increased during the COVID-19 pandemic period (2020–21; 5·1% [0·9–9·6] increase). In contrast with the overall reverse in mortality trends during the pandemic period, child mortality continued to decline, with 4·66 million (3·98–5·50) global deaths in children younger than 5 years in 2021 compared with 5·21 million (4·50–6·01) in 2019. An estimated 131 million (126–137) people died globally from all causes in 2020 and 2021 combined, of which 15·9 million (14·7–17·2) were due to the COVID-19 pandemic (measured by excess mortality, which includes deaths directly due to SARS-CoV-2 infection and those indirectly due to other social, economic, or behavioural changes associated with the pandemic). Excess mortality rates exceeded 150 deaths per 100 000 population during at least one year of the pandemic in 80 countries and territories, whereas 20 nations had a negative excess mortality rate in 2020 or 2021, indicating that all-cause mortality in these countries was lower during the pandemic than expected based on historical trends. Between 1950 and 2021, global life expectancy at birth increased by 22·7 years (20·8–24·8), from 49·0 years (46·7–51·3) to 71·7 years (70·9–72·5). Global life expectancy at birth declined by 1·6 years (1·0–2·2) between 2019 and 2021, reversing historical trends. An increase in life expectancy was only observed in 32 (15·7%) of 204 countries and territories between 2019 and 2021. The global population reached 7·89 billion (7·67–8·13) people in 2021, by which time 56 of 204 countries and territories had peaked and subsequently populations have declined. The largest proportion of population growth between 2020 and 2021 was in sub-Saharan Africa (39·5% [28·4–52·7]) and south Asia (26·3% [9·0–44·7]). From 2000 to 2021, the ratio of the population aged 65 years and older to the population aged younger than 15 years increased in 188 (92·2%) of 204 nations. Interpretation Global adult mortality rates markedly increased during the COVID-19 pandemic in 2020 and 2021, reversing past decreasing trends, while child mortality rates continued to decline, albeit more slowly than in earlier years. Although COVID-19 had a substantial impact on many demographic indicators during the first 2 years of the pandemic, overall global health progress over the 72 years evaluated has been profound, with considerable improvements in mortality and life expectancy. Additionally, we observed a deceleration of global population growth since 2017, despite steady or increasing growth in lower-income countries, combined with a continued global shift of population age structures towards older ages. These demographic changes will likely present future challenges to health systems, economies, and societies. The comprehensive demographic estimates reported here will enable researchers, policy makers, health practitioners, and other key stakeholders to better understand and address the profound changes that have occurred in the global health landscape following the first 2 years of the COVID-19 pandemic, and longer-term trends beyond the pandemic

Versuchsplanung für Prüfung und Bewertung in der humanitären Minenräumung

This thesis proposes a design of experiment for testing and evaluation of the equipment and the methods used in manual mine clearance. The thesis is based on several metal detector trials and a trial of manual demining methods. The core of this dissertation comprises four metal detector trials performed in Germany and Croatia in 2003 and 2005. The purpose of these trials was to investigate the feasibility of the tests described in the CWA (Comit´e Europ´een de Normalisation /CEN/ Workshop Agreement) 14747:-2003, the standard for testing metal detectors for humanitarian demining. The goals of the trials were: to find an appropriate design of experiment for testing metal detectors; to establish the use of ROC diagrams (Receiver Operating Characteristics) and POD curves (Probability of Detection) in the analysis of the experimental results; and to gain practical experience in organising and conducting metal detector trials. A part of this thesis is devoted to a trial of manual demining methods performed in Mozambique in 2004. The main goal of that trial was to compare the speed of various manual demining methods, including the most common excavation methods. The outcome of this work are the proposals and recommendations for an update of the standard for testing metal detectors CWA 14747:2003. Maximum detection height measurements were performed as a part of the metal detector trial carried out in Croatia in 2005. The results reveal a high variability of the maximum detection height. This high variability needs to be taken into account in all experiments. A part of the variability is caused by the differences between the operators and by the setup of the metal detector. It is therefore recommended that two kinds of experiments with the maximum detection height as a response variable are defined in the next update of CWA 14747:2003. The first kind should include the setup, the soil and the operator as factors in the design of experiment. The in-soil measurements with the same detector should be performed with repeated setups and with several operators. The second kind of experiments should be experiments evaluating the influence of other predictor variables. In those experiments, it is recommended to perform one-factor or multiple-factor in-air measurements with the operators and the setup as a block. The main part of the metal detector trials described in this thesis were the detection reliability tests. Detection reliability tests as described in CWA 14747:2003 come closest to representing the real field conditions in demining. They include many environmental influences and, most importantly, many of the human factor influences. However, each test design is a compromise between fully representative conditions and cost effectiveness. In this thesis, a fractional factorial design based on the Graeco-Latin square is proposed as a solution to the experimental problem. The results are reported in the form of ROC diagrams and POD curves. The crossover design enables each operator to work with fewer detector models within a certain time. The variations of the design enabled an unbiased comparison of detectors in each soil and with each target model separately. It is recommended that the solutions proposed in this thesis be incorporated in the standard CWA 14747:2003. It has been shown that maximum detection height measurements provide the information about the best possible performance of a metal detector in a reliability test.Diese Doktorarbeit stellt eine Versuchsplanung für Prüfung und Bewertung von Geräten und Methoden vor, die in der manuellen Minenräumung eingesetzt werden. Die Grundlage hierfür wurde mit einer Reihe von verschiedenen Versuchsreihen zum Test von Metalldetektoren und einer Versuchsreihe zur Untersuchung von ausgewählten manuellen Minenräumtechniken erarbeitet. Im Mittelpunkt dieser Dissertation stehen vier Versuchsreihen zum Test von Metalldetektoren, die in Deutschland und Kroatien in den Jahren 2003 und 2005 durchgeführt wurden. Der Anlass dieser Versuchsreihen war, die Durchführbarkeit der Tests, die im CWA (Comit´e Europ´een de Normalisation /CEN/ Workshop Agreement) 14747:2003, dem europäischen Standard zum Test von Metalldetektoren in der humanitären Minenräumung, beschrieben sind, zu untersuchen. Die Ziele waren, eine geeignete statistische Versuchsplanung zum Test von Metalldetektoren aufzustellen, ROC-Diagramme (Receiver Operating Characteristics) und POD-Kurven (Probability of Detection) für die Analyse der experimentellen Ergebnisse einzuführen und praktische Erfahrungen bei der Organisation und Durchführung von Metalldetektortests zu sammeln. Ein weiterer Teil der Arbeit wurde einer Versuchsreihe auf dem Gebiet der manuellen Mineräumung gewidmet, die im Jahr 2004 in Mosambik durchgeführt wurde. Das Hauptziel dieser Versuchsreihe war, die Geschwindigkeit verschiedener manueller Entminungsmethoden zu vergleichen. Eingeschlossen waren die am häufigsten verwendeten manuellen Ausgrabungsmethoden, die keinen Metalldetektor verwenden. Die Ergebnisse dieser Dissertation sind Vorschläge und Empfehlungen zur Aktualisierung des europäischen Standards zum Test von Metalldetektoren CWA 14747:2003. Als Teil der Versuchsreihe in Kroatien in 2005 wurden Messungen des maximalen Detektionsabstandes durchgeführt. Die Ergebnisse ließen eine hohe Variabilität des maximalen Detektionsabstandes erkennen. Diese hohe Variabilität muss bei allen Experimenten in Betracht gezogen werden. Ein Teil dieser Variabilität wird von den Unterschieden zwischen den bedienenden Personen und der Geräteeinstellung hervorgerufen. Deshalb werden für die nächste Aktualisierung des CWA 14747:2003 zwei verschiedene Arten von Experimenten mit dem maximalen Detektionsabstand als Zielvariable empfohlen. Die erste sollte die Geräteeinstellung, den Bodentyp und das bedienende Personal als Faktoren in der Versuchsplanung enthalten. Die Messungen im Boden sollten mit wiederholten Geräteeinstellungen und verschiedenen Personen durchgeführt werden. Die zweite Art von Experimenten sollte die Bewertung des Einflusses von anderen Wirkungsvariablen beinhalten. Bei diesen Versuchen wird empfohlen die Experimente mit einem oder mehreren Faktoren in Luft durchzuführen, wobei die bedienenden Personen und die Geräteeinstellung jeweils für sich einen Block bilden. Die Zuverlässigkeitstests zur Minendetektion, beschrieben im CWA 14747:2003, kommen realen Bedingungen bei der Entminung am nächsten. Darin enthalten sind sowohl viele der Umweltbedingungen als auch viele der überaus wichtigen Einflüsse des Faktors Mensch. Jede Versuchsplanung stellt jedoch einen Kompromiss zwischen vollständig repräsentativen Bedingungen und der Kosteneffektivität dar. Zur Lösung dieses experimentellen Problems wird in dieser Doktorarbeit die fraktionell faktorielle Versuchsplanung basierend auf dem griechisch-lateinischen Quadrat vorgestellt. Die Versuchsergebnisse werden in Form von ROC-Diagrammen und POD-Kurven dargestellt. Die Überkreuz-Planung (”crossover design”) ermöglicht, dass jede Person nur wenige Geräte in einem bestimmten Zeitabschnitt bedient. Die Variationen in der Versuchsplanung erlauben weiterhin einen erwartungstreuen Vergleich der Leistungen der Detektoren in jedem Boden und bei jedem Minentyp separat. Es wird empfohlen, die in dieser Dissertation vorgeschlagenen Lösungen in die nächste Version des Standards CWA 14747:2003 einzuarbeiten. Es wurde nachgewiesen, dass die systematischen Messungen des maximalen Detektionsabstandes die bestmögliche Leistung eines Detektors in einem Zuverlässigkeitstest wiedergeben

Air-Coupled Ultrasonic Ferroelectret Receiver with Additional DC Voltage

Highly sensitive air-coupled ultrasonic sensors are essential for various applications such as testing of composite materials. One of the major challenges for the development of air-coupled ultrasonic sensors is the impedance matching to air. With a lower acoustic impedance than the usual piezoelectric materials, charged cellular polypropylene film (cPP) offers better matching to air with a similar piezoelectric coefficient. The piezoelectric behaviour demonstrated by cPP comes from polarized air cells that create a permanent internal voltage. The sensitivity of the sensor varies with the application of an additional DC bias voltage. Thus, this work presents a cPP ultrasonic sensor with an improvement of up to 15 ± 1 dB on the signal-to-noise ratio

Broadband Air-Coupled Ultrasound Emitter and Receiver Enable Simultaneous Measurement of Thickness and Speed of Sound in Solids

Air-coupled ultrasound sensors have advantages over contact ultrasound sensors when a sample should not become contaminated or influenced by the couplant or the measurement has to be a fast and automated inline process. Thereby, air-coupled transducers must emit high-energy pulses due to the low air-to-solid power transmission ratios (10−3 to 10−8). Currently used resonant transducers trade bandwidth—a prerequisite for material parameter analysis—against pulse energy. Here we show that a combination of a non-resonant ultrasound emitter and a non-resonant detector enables the generation and detection of pulses that are both high in amplitude (130 dB) and bandwidth (2 µs pulse width). We further show an initial application: the detection of reflections inside of a carbon fiber reinforced plastic plate with thicknesses between 1.7 mm and 10 mm. As the sensors work contact-free, the time of flight and the period of the in-plate reflections are independent parameters. Hence, a variation of ultrasound velocity is distinguishable from a variation of plate thickness and both properties are determined simultaneously. The sensor combination is likely to find numerous industrial applications necessitating high automation capacity and opens possibilities for air-coupled, single-side ultrasonic inspection