Time-frequency representation of earthquake accelerograms and inelastic structural response records using the adaptive chirplet decomposition and empirical mode decomposition

In this paper, the adaptive chirplet decomposition combined with the Wigner-Ville transform and the empirical mode decomposition combined with the Hilbert transform are employed to process various non-stationary signals (strong ground motions and structural responses). The efficacy of these two adaptive techniques for capturing the temporal evolution of the frequency content of specific seismic signals is assessed. In this respect, two near-field and two far-field seismic accelerograms are analyzed. Further, a similar analysis is performed for records pertaining to the response of a 20-story steel frame benchmark building excited by one of the four accelerograms scaled by appropriate factors to simulate undamaged and severely damaged conditions for the structure. It is shown that the derived joint time–frequency representations of the response time histories capture quite effectively the influence of non-linearity on the variation of the effective natural frequencies of a structural system during the evolution of a seismic event; in this context, tracing the mean instantaneous frequency of records of critical structural responses is adopted. The study suggests, overall, that the aforementioned techniques are quite viable tools for detecting and monitoring damage to constructed facilities exposed to seismic excitations

Influencia de reemplazo de ceniza de caña de azúcar sobre las propiedades físicas y mecánicas de adoquines tipo II para pavimentos de tránsito liviano, Trujillo 2019

El presente proyecto de investigación se desarrolló en la ciudad de Trujillo en el laboratorio de la Universidad Privada del Norte, se determinó la influencia del porcentaje de ceniza de caña de azúcar sobre las propiedades físicas y mecánicas de adoquines tipo II para tránsito liviano. En el diseño de mezcla, se realizaron ensayos según las normas técnicas peruanas (NTP) para la caracterización de los agregados, así como para la resistencia a la compresión se empleó la NTP. La presente investigación es de tipo experimental, porque por medio de la manipulación de la variable independiente, porcentaje de la ceniza de caña de azúcar, se determinará la influencia que genera sobre la variable dependiente: la adición de ceniza de caña de azúcar mejorara las propiedades físicas y mecánicas de los adoquines, en cuanto el diseño de la investigación es experimental puro, ya que se puede controlar y limitar las variaciones de la ceniza. Se concluyó que se influye de manera positiva en la resistencia a la compresión a edades de 7, 14 y 28 días con respecto al patrón, también se pudo comprobar que agregando la ceniza de caña de azúcar hasta el 12 % aumenta la resistencia a la compresión y a partir del 15% ya empieza a disminuir por debajo del patrón, de la misma manera sucede en el ensayo de absorción a menor cantidad de ceniza mayor es la cantidad de agua que absorbe y a mayor cantidad de ceniza menor es la cantidad de agua que absorbe.This research project was developed in the city of Trujillo in the laboratory of the Universidad Privada del Norte, the influence of the percentage of sugarcane ash on the physical and mechanical properties of type II pavers for light traffic was determined. In the mix design, tests were carried out according to the Peruvian technical standards (NTP) for the characterization of the aggregates, as well as for the compressive strength the NTP was used. The present investigation is of an experimental type, because through the manipulation of the independent variable, percentage of sugarcane ash, the influence it generates on the dependent variable will be determined: the addition of sugarcane ash will improve the properties physical and mechanical pavers, as the research design is pure experimental, since it is possible to control and limit ash variations. It was concluded that the compressive strength is positively influenced at ages 7, 14 and 28 days with respect to the pattern, it was also found that adding sugarcane ash up to 12% increases the compressive strength and starting at 15% it already begins to decrease below the standard, in the same way it happens in the absorption test at a lower amount of ash the greater the amount of water it absorbs and the greater the amount of ash the lower the amount of water it absorbs

Potential trade-offs between eliminating plastics and mitigating climate change: An LCA perspective on Polyethylene Terephthalate (PET) bottles in Cornwall

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordThe aim of this study is to investigate whether eliminating plastics entirely under existing waste infrastructure and management practices could have an adverse effect on climate change, using a case study on the hypothetical substitution of Polyethylene Terephthalate (PET) with glass as the material for bottling liquids in the domestic sector in Cornwall, England. A life cycle environmental impacts-based model was created using high resolution local data on household waste and current management practices in combination with Life Cycle Assessment (LCA) datasets. The model allows users to define key system parameters such as masses of materials, transport options and end-of-life processes and produces results for 11 environmental impact categories including the Global Warming Potential (GWP). The results from the application of this model on the case study of Cornwall have shown that the substitution of PET with glass as the material for bottling under the current waste infrastructure and management practices could lead to significant increases in GWP and hinder efforts to tackle climate change. A sensitivity analysis of the glass/PET mass ratio suggests that in order to achieve equal GWP the glass bottles need to become approximately 38% of the weight they are now. Increasing the recycled content and decreasing losses during the recycling processes could also help lower the GWP by 18.9% and 14.5%, respectively. This model can be expanded further to include more types of plastics and other regions to evaluate designs of new regional circular economy with less plastics waste and pollution. Our study suggests that it is necessary and crucial to consider the specific waste infrastructure and management practices in place and use science-based models that incorporate life cycle thinking to evaluate any solutions to plastics pollution in order to avoid problem shifting.Engineering and Physical Sciences Research Council (EPSRC

Novel Procedure for Laboratory Scale Production of Composite Functional Filaments for Additive Manufacturing

Successful 3D printing by material extrusion of functional parts for new devices requires high quality filaments. Uniform homogeneity and good dispersion of particles embedded in filaments typically takes several cycles of extrusion or well-prepared feedstock by injection molding, industrial kneaders or twin-screw compounding. These methods need specific production devices that are not available in many laboratories non-specialized in polymer research, such as those working on different material science and technology topics that try to connect with additive manufacturing. Therefore, laboratory studies are usually limited to compositions and filler concentrations provided by commercial companies. Here, we present an original laboratory scale methodology to custom-prepare the feedstock for extruding magnetic composite filaments for fused filament fabrication (FFF), which is attainable by a desktop single-screw extruder. It consists in encapsulating the fillers in custom made capsules that are used as feedstock and reach the melting area of the extruder maintaining the same concentration of fillers. Results have shown that our approach can create smooth and continuous composite filaments with good homogeneity and printability with fine level of dimensional control. We further show the good dispersion of the particles in the composite filament using X-Ray Tomography, which enabled a 3D reconstruction of the spacial distribution of the embedded magnetic particles. The major advantage of this new way of preparing the composite feedstock is that it avoids the hassle of multiple extrusion runs and industrial machinery, yet providing uniform filaments of well controlled filler concentration, which is predictable and reproducible. The proposed methodology is suitable for different polymer matrices and applicable to other functional particle types, not just limited to magnetic ones. This opens an avenue for further laboratory scale development of novel functional composite filaments, useful for any community. This democratization of complex filament preparation, including consumers preparing their own desired uniform novel filaments, will facilitate to unify efforts nearing 3D printing of new functional devices.Fondo Europeo de Desarrollo Regional MAT-201677265-RJunta de Andalucía US-1260179, P18-RT-74

Understanding the urbanization impacts of high-speed rail in China

Advances in transport technology have been shown to play a vital role in urban development over millennia. From the engineering and pavement innovations of the Roman road network to the aerospace breakthroughs that enabled jet aircraft, cities have been reshaped by the mobility changes resulting from new designs for moving people and goods. This article explores the urbanization impacts of High-Speed Rail’s introduction in China, which has built the world’s largest High-Speed Rail network in record time. Since High-Speed Rail was launched in Japan in 1964, this technology has worked to reshape intercity travel as a revolutionary transportation alternative. High-Speed Rail has developed steadily across Japan, France, Germany, Italy, Switzerland during the 1970s and 1980s. It expanded to Russia, Spain, the United Kingdom, and Sweden in the 1990s. In the 21st century, China began developing High-Speed Rail on an unprecedented scale, and now has a national network that is longer than the totality of the rest of the world’s High-Speed Rail operations combined. China’s High-Speed Rail operation is exerting a transformative influence on urban form and function. This article synthesizes secondary research results to analyse the impacts of HSR on urbanization. These effects include population redistribution, urban spatial expansion and industrial development. We offer a typol-ogy that considers the urban effects of High-Speed Rail at three spatial levels: the station area, the urban jurisdiction, and the regional agglomeration. When organized through our typology, research findings demonstrate that High-Speed Rail influences urban population size, urban spatial layout and industrial development by changing the acces-sibility of cities. We highlight the processes by which High-Speed Rail ultimately affects the urbanization process for people, land use, and industrial development. However, High-Speed Rail’s impacts on urbanization are not always positive. While leveraging the development opportunity enabled by High-Speed Rail, governments around the world should also avoid potential negative impacts by drawing lessons from the experience of High-Speed Rail’s rapid de-ployment in China

Quantification of plastics in agriculture and fisheries at a regional scale: A case study of South West England

This is the final version. Available from MDPI via the DOI in this record. Data Availability Statement: All data in this study are available through the online links provided throughout the document, except the data provided by FWAG, which needs to be requested.The use of plastics in agriculture and in fisheries has been vital to increase food production and meet the demands of an increasingly growing global population. However, there are several drawbacks to the use of plastics in these industries. Most plastics used in agriculture are disposed of after one single use and are highly susceptible to weathering. Abandoned, lost, or discarded fishing gear cause considerable damage to marine life. Quantification of plastic waste generation in these industries is scarce or non-existent in the case of fisheries. In this paper, we estimate the amount of plastic waste generated by agriculture and fisheries at a regional scale, considering the South West of the UK as a case study. We followed a mass balance approach to quantify the potential plastic waste generated by these industries. We find a generation of 49 kt of plastic waste in agriculture, 47% of which has an unknown fate. We estimate 454 t/year of fishing gear waste, with unclear end-of-life pathways. A detailed quantitative understanding of plastic waste generation per sector at a regional scale is fundamental for tracking plastic waste flows, locating hotspots of pollution, and planning actions to reduce the amount of plastic waste along the chain of end-users.Engineering and Physical Sciences Research Council (EPSRC

OPTICAL FIBER-BASED SENSORS AND THEIR RECENT APPLICATIONS IN SCIENCE AND ENGINEERING

Este artículo presenta una revisión de los sensores basados en fibra óptica y sus principales características y clasificación. Del mismo modo, el artículo incluye una serie de aplicaciones de sensores basados en fibra óptica con rejillas de Bragg en diferentes campos de estudio de la investigación como la medicina, la ingeniería civil, la ingeniería de comunicaciones, la química y la bioquímica, entre otros. Dichos sensores se desarrollan aprovechando ciertas características de las fibras ópticas, como la fotosensibilidad y la variación del índice de refracción de su núcleo. También se analizan las aplicaciones de la fibra óptica en la detección de señales de telecomunicaciones, en particular como dispositivo de filtrado mediante el uso de rejillas de Bragg. Debido a su versatilidad, estos dispositivos ópticos han proporcionado resultados prometedores y se han convertido en una tecnología líder en los sistemas DWDM de próxima generación, así como en las redes de detección óptica. This paper presents a review of fiber optic-based sensors and their main characteristics and classification. In the same way, the paper includes a series of applications of sensors based on fiber optics with Bragg gratings in different fields of study in research such as medicine, civil engineering, communications engineering, chemistry, and biochemistry, among others. Such sensors are developed taking advantage of certain characteristics of optical fibers, such as photosensitivity and the variation of the refractive index of their core.  Applications of fiber optics in the detection of telecommunications signals are also discussed, particularly as a filter device through the usage of Bragg gratings. Due to its versatility, these optical devices have provided promising results and have become a leading technology in next generation DWDM systems, as well as in optical sensing networks.&nbsp

Identification of dynamic displacements and modal frequencies of amedium-span suspension bridge using multimode GNSS processing

Global Navigation Satellite System (GNSS) positioning technology has been employed in the dynamic monitoring of long-span bridges in the recent years. However, it has difficulties to meet the higher accuracy requirements of the dynamic monitoring of small or medium span bridges, due to the presence of measurement noise from multipath, cycle slips, ionosphere delay, orbital errors, etc. To verify the feasibility of using current GNSS technology to monitor these bridges, a series of monitoring experiments have been carried out on the Wilford suspension bridge in Nottingham (UK) with GNSS and a triaxial accelerometer. Three GNSS data processing modes, i.e. Real-Time Kinematic (RTK), network RTK and Post-Processing Kinematic (PPK), were considered. An innovative multimode adaptive filtering (MAF) that combining adaptive filter with Chebyshev highpass filter was used to identify the dynamic displacements of the bridge from the multimode GNSS data. To validate the GNSS results, the dynamic displacements were also computed from double integration of the accelerometer-measured accelerations. The differences of the displacements between the GNSS and accelerometer results were obtained. The standard deviation and the mean deviation of these differences are less than 1 mm, which is good enough for the monitoring purposes. The modal frequencies of the bridge can be accurately identified from GNSS measurements, and successfully validated by those from the accelerometer data. Using the multimode GNSS data and the proposed the MAF algorithm, with sub-millimeter level accuracy GNSS can be used to monitor the vibration response of small or medium span bridges as well as long-span bridges

Reasons of Singles for Being Single:Evidence from Brazil, China, Czech Republic, Greece, Hungary, India, Japan and the UK

The current research aimed to examine the reasons people are single, that is, not in an intimate relationship, across eight different countries—Brazil, China, Czech Republic, Greece, Hungary, India, Japan, and the UK. We asked a large cross-cultural sample of single participants (N = 6,822) to rate 92 different possible reasons for being single. These reasons were classified into 12 factors, including one’s perceived inability to find the right partner, the perception that one is not good at flirting, and the desire to focus on one’s career. Significant sex and age effects were found for most factors. The extracted factors were further classified into three separate domains: Perceived poor capacity to attract mates, desiring the freedom of choice, and currently being in between relationships. The domain structure, the relative importance of each factor and domain, as well as sex and age effects were relatively consistent across countries. There were also important differences however, including the differing effect sizes of sex and age effects between countries