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The influence of atmospheric drivers, environmental factors, and urban land use on extreme hourly precipitation trends over the CONtiguous United States for 40 years at 4-km resolution (CONUS404)
No full textHigh-resolution datasets provide unique insights into extreme precipitation dynamics, capturing atmospheric, environmental, and anthropogenic influences missed by coarser data. Here, we use the 4 km CONUS404 dataset (1980–2021) to analyze trends in extreme hourly precipitation across the contiguous USA and adjacent regions. Using the 42 highest hourly precipitation values (HP42) from the 42-year dataset, we estimate regression slopes for their annual occurrence and intensity. ANOVA analysis examines the effects of elevation and land use on HP42 trends, while Multiple Linear Regression (MLR) assesses the effects of atmospheric drivers (dew point temperature, El Niño, La Niña, and North Atlantic Oscillation). Positive frequency slopes dominate central and northeastern regions, while decreases occur in the West and Southwest. Magnitude slopes are less spatially consistent but near zero in the high-elevation, arid regions of the West. Dew point temperature (TD) drives magnitude trends, while frequency trends are influenced by TD, La Niña, and the positive North Atlantic Oscillation index. Elevation significantly shapes frequency trends, with higher trends at lower and medium elevations (200–1000 m) and weaker trends above 1500 m. Land use impacts vary with elevation; Urban areas show decreasing frequency across several elevations, while natural land uses such as forests and wetlands often exhibit an increase or stabilization in precipitation trends at various elevations. Aggregating variables to coarser resolutions improves MLR model performance, unveiling significant factors by reducing noise. Hotspot analysis reveals that larger cities (e.g., New York, Los Angeles) have concentrated precipitation hotspots, while smaller cities (e.g., Memphis and Nashville) exhibit scattered trends. The overlap between frequency and magnitude clusters highlights shared drivers, suggesting increased vulnerability in peri-urban areas. These findings underscore the need for adaptive strategies addressing the complex interplay of urbanization, elevation, and climate factors
Procedure for the multi-objective design and sustainability optimization of composite sandwich structures in aircraft cabin applications
No full textIn engineering, optimizing products across multiple performance metrics - such as cost, weight, and environmental sustainability - presents a significant challenge. Composite sandwich structures, in particular, offer a vast design space with diverse materials and geometric parameters, leading to conflicting design objectives. This study presents a procedure integrating Genetic Algorithms (GA), Finite Element Analysis (FEA), and rule-based performance metric calculations to address these challenges. GA facilitate efficient exploration of the design space, while via FEA mechanical performance is evaluated, and via rule-based calculations economic and ecological metrics are assessed. The procedure is applied to an aircraft partition-like sandwich structure, demonstrating its effectiveness in balancing trade-offs and achieving holistic design optimization. This approach provides valuable tools and insights for engineers and designers working with advanced composite materials, highlighting its potential to support sustainable development and informed decision-making in product design
Innovative responses to copycats: insights from China's restaurant industry
No full textThis study delves into a pressing issue in the restaurant industry: the challenge of catering copycats, which are unauthorized imitations of menu items and services that can lead to lost market share and hinder innovation. Focusing on Chinese restaurants, it employs multi-wave surveys and analyzes 929 responses to investigate the impact of copycat threats on innovation. The study reveals both linear and nonlinear effects of these threats, highlighting the role of customer and supplier co-creation as mediators. It underscores the importance of understanding how different types of restaurants vary in their innovative responses to imitation. The research enriches the behavior of the firm theory by demonstrating how restaurants can proactively drive innovation in the face of imitation. It extends the applicability of value co-creation theory, illustrating the role of interactions with suppliers and customers in shaping innovative strategies, thereby enhancing dynamic capabilities to adapt to market demands and changes
Opening the floodgates : How big companies can reap the benefits of internal crowdfunding
No full textDigital technologies enable employees at all levels to participate in distributed decision-making. We examine the design principles, benefits, and challenges of a new type of distributed decision-making: internal crowdfunding. We build on a five-year case study of internal crowdfunding contests at Siemens AG to deepen our understanding of the design principles of internal crowdfunding and its potential for corporate innovation. Based on this data, we discuss the three design choices in internal crowdfunding (contributors, configuration, and control), find four key benefits (decentralization, cross-collaboration, institutionalization, and intrapreneurship), and identify three key challenges (dealing with rejected ideas, evaluation biases, and implementation and follow-on funding) and potential actions by managers to overcome them. The paper contributes to both the emerging literature on internal crowdfunding and the literature on distributed decision-making
Experimental validation for the combination of funnel control with a feedforward control strategy
No full textCurrent engineering design trends, such as lightweight machines and human–machine interaction, often lead to underactuated systems. Output trajectory tracking of such systems is a challenging control problem. Here, we use a two-design-degree of freedom control approach by combining funnel feedback control with feedforward control based on servo-constraints. We present experimental results to verify the approach and demonstrate that the addition of a feedforward controller mitigates drawbacks of the funnel controller. We also present new experimental results for the real-time implementation of a feedforward controller based on servo-constraints on a minimum phase system.Deutsche Forschungsgemeinschaft (DFG
Magnetic resonance imaging in granular flows: An overview of recent advances
No full textIn this review we explore the recent developments in the use of Magnetic Resonance Imaging (MRI) for studying granular flows. While MRI has been a valuable tool in this field for the past 40 years, recent advances in imaging hardware, reconstruction software and particles synthesis have significantly enhanced its capabilities. This article provides an overview of the current challenges of MRI and progress in the field of granular media, and gives a perspective of the possible future developments in the field
Synthesis and Application of Ti/La Based Composite Catalyst for Triglyceride Conversion into Biodiesel
No full textThe search for substitute fuels has motivated researchers to explore alternate attractive options such as conversion of used oils to biodiesel. This study is focused on the production of biodiesel from waste cooking oil by developing a porcelain supported titanium and lanthanum oxide based composite catalyst. This heterogeneous composite catalyst was synthesized by the wet-impregnation method. The reaction procedure as well as reaction parameters like methanol to oil molar ratio, different catalyst loading, reaction temperature, reaction time, and reusability of catalyst was investigated. The results show that with the help of Ti: La: Porcelain, the yield of biodiesel produced was 94% at ≥ 90°C in 7 h. For both catalysts, 5 wt% of catalyst based on oil, 36:1 methanol/oil molar ratio was reused 5 times with regeneration. Different characterization of porcelain supported titanium and lanthanum Oxides before and after trans-esterification were performed using x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive x-ray spectroscopy (EDS) techniques. The high-performance liquid chromatography (HPLC) technique was used to analyze synthesized biodiesel. The physiochemical properties of the synthesized biodiesel were performed as well, and color changes were also scrutinized. A static immersion test of copper, aluminum, zinc, iron and stainless steel in the blend of prepared biodiesel/diesel was conducted at room temperature (25 –27 °C) for 720 h utilizing the conventional method of measuring weight loss. The findings of the study revealed that blend of biodiesel/diesel sample was less corrosive to these materials compared to literature at room temperature
Using generic cities to assess flying ad-hoc network (FANET) performance
No full textFlying ad-hoc networks (FANET) offer a solution to provide communication among unmanned aerial systems (UAS) without ground infrastructure and, hence, may provide redundancy if main terrestrial communication systems fail. With a strongly growing UAS market, this redundancy is of particular importance especially if the vehicles are operated over densely populated regions, such as urban areas. To further develop the FANET technology, it is, therefore, essential to understand and predict the performance requirements for such networks and the necessary systems as they arise from the different applications. However, with the diversity of cities, the problem arises that custom-made simulation models often lack generality. For this reason, in our work, we introduce an approach to generate randomized cities and to model UAS traffic for selected applications to assess different performance metrics of the FANET. This approach comprises the creation of randomized city geometries, the derivation of UAS traffic demand on these geometries, as well as the simulation of the flights of each individual vehicle. To showcase the capabilities of the approach, we generate an exemplary city and obtain characteristic datasets of the UAS traffic which are then used to assess the FANET performance for a selected FANET application using a simplified network model. We will show that FANET performance is strongly influenced by the extent of the demand, demand distribution over time, vehicle speed, and delivery network geometry
Multiscale investigations of mechanobiology: in vitro observations and computational modeling
No full textMechanobiology is an inherently multiscale field of study that explores the relationship between mechanical forces and biological processes at various levels, from molecular and cellular to tissue and organ levels. This work presents different aspects of this multiscale system, ranging from cell migration to mechanical testing of tissue equivalents to computational modeling of tissue adaptation. The results help identify key macroscopic quantities and (sub)cellular mechanisms essential in regulating biological processes on different length and time scales in response to mechanical perturbations.Mechanobiologie befasst sich mit dem Einfluss mechanischer Reize auf biologische Prozesse und umfasst mehrere Längen- und Zeitskalen, von individuellen Molekülen über Zellen bis hin zu Organen. Diese Arbeit stellt diverse Aspekte dieses multiskalen Systems anhand von Experimenten und Computermodellen dar und beschäftigt sich vor allem mit der Zellmigration, dem mechanischen Verhalten von Gewebeäquivalenten und der Anpassung von Weichgewebe. Die Ergebnisse der einzelnen Studien heben dabei makroskopische Größen sowie inter- und intrazelluläre Mechanismen hervor, die eine wichtige Rolle bei der mechanischen Regulierung biologischer Prozesse spielen