59 research outputs found
An Experimental Analysis on the Readiness of Currently-Deployed 5G Networks for Positioning
No full textThis article studies the positioning capabilities offered by currently operational fifth-generation (5G) cellular networks operating in the n78 band. We consider four mobile operators in Milan, Italy, and compare their network readiness for positioning by passively measuring and analyzing the time of arrival (ToA) and the received power extracted from synchronization signal blocks (SSBs) signals periodically broadcasted by the base stations (BS). We focus on urban and rural areas, showing that the TOA accuracy significantly varies over the two types of areas and among network operators. Our operator-agnostic analysis reveals that the current state of network synchronization presents strong issues that hinder positioning services at present. Major efforts on synchronization protocols and technologies are required by telecommunication manufacturers and operators
Functional response of graminoid species to changing summer water availability: insight into the effects of climate change in sub-Mediterranean meadows
No full textWe measured leaf area, dry mass and plant height and calculated SLA on randomly collected leaf samples of dominant graminoid species (three replicates for each treatment with different watering frequency), at three times of one growing season, and tested the effect of treatments on these variables, controlling for phenological state of plant, leaf state and time of data collection.
We found that in some perennial late spring/early summer-flowering species (i.e. Cynosurus cristatus and Lolium perenne), reduced rainfall, jointly with phenological phase and time, affected in the same direction both leaf area and dry mass, leaving SLA values substantially unchanged during the growing season. Additional rain increased significantly SLA in Cynosurus cristatus, due to a higher increase in leaf area than in dry mass. In other perennial species (i.e. Arrhenatherum elatius and Elymus repens) with later reproductive cycle, increase in drought caused a significant decrease in SLA, associated to a reduction in leaf area, especially at the end of the treatment (summer end), indicating a shift of plant strategy to a lower efficiency in resource acquisition and use. Contrariwise, the increase in drought within a growing season, had a modest influence on plant height. These results suggest that response patterns of leaf traits to reduced water availability are species-specific and are probably linked to species’ functional structure
Species trait syndrome drives the leaves’ functional variations of dominant grasses to modifications in summer water supply
No full textClimate change models predict a strong reduction of average precipitation, especially of the summer rainfall, and an increase in intensity and frequency of drought events in the Mediterranean region. The research aim was to understand how four dominant grass species (Arrhenatherum elatius, Cynosurus cristatus, Elymus repens, and Lolium perenne) in sub-Mediterranean meadows (central Apennines, Italy) modulate their resource acquisition and conservation strategies to short-term variation of the pattern of summer water supply. During summer 2016, using a randomized block design, we tested the effect of three patterns of summer water supply, differing in water amount and watering frequency, on leaf area, leaf dry mass, specific leaf area (SLA), leaf senescence, and plant height. Our results showed that dominant grass species can modulate their strategies to variation of the pattern of summer water supply, but the response of leaf traits and plant height is mediated by the set of functional characteristics of the species. E. repens and A. elatius, with summer green leaves, lower SLA, later flowering period, and deeper roots, were less influenced by changes in water amount. C. cristatus and L. perenne, which display acquisitive strategies (persistent leaves, higher SLA values), earlier flowering, and shallower roots were more influenced by changes in the pattern of summer water supply. Our results suggest that a short-term decrease in water availability might affect primarily species with trait syndromes less adapted to face summer drought
Integration of 5G and GNSS Technologies for Enhanced Positioning: An Experimental Study
No full textThis paper presents an experimental study on the integration of the fifth generation (5G) cellular network and the Global Navigation Satellite System (GNSS) for positioning. Along with the use of experimental data collected from both 5G and GNSS deployed technologies, the novelty of this research includes the design of a Bayesian tracking methodology based on extended Kalman filtering for processing the 5G Time of Flights (TOFs) and jointly estimating the user position and the clock offsets of the 5G Base Stations (BSs), as well for their fusion with GNSS observations (both single and dual frequency). Data collection and experimental analyses are conducted in both static and mobile positioning scenarios. For standalone 5G positioning, we demonstrate the need of tracking the clock offsets of BSs, as they currently represent a primary impairment for precise positioning. In static conditions, we manage to reduce the positioning error from more than 100 m to approximately 5 m by jointly estimating these offsets and correct the TOFs accordingly, showcasing that the current 5G network is a possible alternative to single frequency code-only GNSS positioning. The 5G+GNSS hybrid solution is shown to guarantee a more reliable and accurate positioning as the two technologies mutually assist each other, particularly when single frequency GNSS processing is considered. On the other hand, when the GNSS receiver is able to perform dual frequency processing, location estimation does not benefit from the hybridization with 5G as GNSS is already highly accurate. Overall, the achieved results confirm the viability of 5G+GNSS integration from an experimental standpoint, showing the potentialities of the currently-deployed 5G network for positioning
Urban overheating mitigation through facades: the role of new and innovative cool coatings
No full textIndustrialized renovation of the building envelope: realizing the potential to decarbonize the European building stock
No full textGiven the European building stock’s current size and state, its potential to be renovated up to an energy-neutral quality is getting much attention, contributing to energy transition and other sustainable and societal benefits. To tackle this potential, both the number of buildings that undergo renovation and the amount of the resulting energy savings need to increase. Industrialization and prefabrication of renovation are effective strategies to improve productivity, achieve high energy performance and minimize on-site construction time. This chapter investigates current practices and future potential for industrialized renovation of the building envelope. The definitions and application of industrialized techniques in the design and construction of renovation are discussed, particularly regarding the renovation process and design concepts. Finally, the chapter provides an outlook on essential aspects for the future implementation of industrialized building envelope retrofit. Understanding current practices and how to improve industrialized renovation is instrumental to the upscaling of renovation that leads to the decarbonization of the building stock.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Building Product InnovationDesign of Construtio
FORGOTTEN PAGES FROM ION MACOVEI’S CREATION
No full textThis article is devoted to Ion Macovei’s creation, namely, to his Symphonieta Florile dalbe (lily-whiteflowers) in the version for string orchestra, realized by conductor Dumitru Goia. The author presents some information about the history of this creation and analyses the six-part cycle of the Symphonieta, where every movement has its own title in Latin. The character of these miniatures which are closely connected with Moldova calendar folklore, and first of all, with the carol genre, determined the use of both archetypes of the monodic melody and of the early heterophony principles as well as the mode systems characteristic of regional musical folklore. here is also an analysis of the methods of orchestration used by Dumitru Goia in the score of the Symphonieta
A feasibility study of 5G positioning with current cellular network deployment
No full textThis research examines the feasibility of using synchronization signals broadcasted by currently deployed fifth generation (5G) cellular networks to determine the position of a static receiver. The main focus lies on the analysis of synchronization among the base stations of a real 5G network in Milan, Italy, as this has a major impact on the accuracy of localization based on time of arrival measurements. Understanding such properties, indeed, is fundamental to characterize the clock drifts and implement compensation strategies as well as to identify the direct communication beam. The paper shows how the clock errors, i.e., inaccurate synchronization, among 5G base stations exhibit a significant bias, which is detrimental for precise cellular positioning. By compensating the synchronization errors of devices' clocks, we demonstrate that it is in principle possible to localize a static user with an accuracy of approximately 8-10 m in non-obstructed visibility conditions, for urban and rural scenarios, using the deployed 5G network operating at 3.68 GHz and relying on broadcast signals as defined by 5G Release 15 standard. This work has been funded by the European Space Agency (ESA) Navigation Innovation and Support Program (NAVISP) Element 2 pillar which aims at improving the competitiveness of the industry of the participating States in the global Positioning, Navigation and Timing (PNT) market
CFD Study of Diffuse Ceiling Ventilation through Perforated Ceiling Panels
No full textDiffuse Ceiling Ventilation (DCV) is a promising concept to address internal air quality and thermal comfort requirements in contemporary buildings. Sound-absorbing perforated ceiling panels are common in office rooms and can be used as air diffusers without modifications. The optimization of such systems is not a trivial procedure, and numerical simulation can represent an important tool to carry out this task. Today, most of the numerical studies on DCV are performed using porous medium models and focus on the general system performance rather than on the optimization of the diffuser design. In previous studies, a CFD model was used to optimize the size and distribution of the ceiling perforation. In the study presented in this paper, the results of simulations conducted on a full-scale three-dimensional domain and the performance comparison between a continuous and non-continuous perforation distribution are given. The results show that the non-continuous diffuser design does not disturb the internal comfort and does not introduce a negative effect in the system performance. The different configurations lead to a different air distribution in the room, but in both cases, the velocity magnitude is always well below values leading to draft discomfort
Numerical investigation of a diffuse ventilation ceiling system for buildings with natural and hybrid ventilation
No full textThe need to meet requirements, both in terms of ventilation and thermal comfort in modern buildings, has led to the development of different concepts for ventilation, among which the so-called Diffuse Ceiling Ventilation (DCV). This system makes use of the space between the ceiling slabs and the suspended ceiling as a plenum for fresh air, while the suspended ceiling itself becomes an air diffuser element. If compared to traditional solutions, this allows a higher amount of ventilation air to be injected in the room at lower speed, and a more even distribution of the fresh air within the room. Furthermore, it allows an easy integration with sound-absorbing perforated ceiling panels, since their typical design makes them particularly fit to be used as air diffusers. This paper builds upon a previous work by the authors where CFD simulations were used to optimise the dimension and the distribution of the perforation pattern in the panels to achieve an even air speed distribution. In this work, the performance of the perforated ceiling is investigated in a more comprehensive way, evaluating the thermal comfort in the room when varying the outdoor temperature. This solution is in fact meant to work in combination with natural or hybrid ventilation strategies, where the fresh air flow is supplied from the façade. Numerical simulations were performed on a typical office room, considering both the winter and the summer season, for different inlet air temperatures. This solution demonstrated a positive impact on the indoor conditions and on the thermal comfort inside the room in most of the cases but the most extreme ones. The thermal stratification in the room demonstrated to remain within a satisfactory level
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