565 research outputs found
A Geometric Approach to Multiple Viewpoint Human Body Pose Estimation
No full textPeople detection and re-identification is a crucial capability for mobile robots working in a human environment, as well as for human-robot interaction. Re-identification systems can be based on the observation of a number of cues, including the analysis of the human body pose, that can be accurately detected analyzing RGB-D data, currently widely used in robot vision. On the other hand, intelligent video surveillance is going towards multi-viewpoint RGB camera systems: skeletal trackers working on images are currently unable to provide performance similar to those based on 3D data. To overcome such flaws, this paper proposes a method for merging together the results provided by a body pose estimation algorithm observing the same scene from different viewpoints: this enhances the accuracy level, and lets the system recover 3D information, leading to a target representation which is more similar to the one obtained using 3D sensors. Such similarity is a first step to achieve a stronger cooperation between robots and camera networks, a capability that opens new scenarios in robotics
Design and performance of a nozzle-type rainfall simulator for landslide triggering experiments
No full textRainfall simulators represent a widespread tool for studying hydrologic processes involving interactions of rainwater with soils, such as soil erosion, overland flow generation, and infiltration. Nevertheless, researchers must often develop devices suiting their particular needs, due to a lack of a standard design. In this case, a rainfall simulator was needed for the production of heavy rainfall, to be applied for the study of infiltration dynamics and landslide triggering on an artificial hillslope with a planar size of 2 m by 6 m. Therefore, the goal of this study was to design and test a rainfall simulator characterized by the following main properties: i) range of rainfall intensity varying from 50 to 150 mm/h, ii) spatial uniformity of the produced rain of at least 80%, and iii) limited impact energy on the soil in order to avoid surface erosion, which can alter the infiltration processes responsible for the landslide triggering. To achieve these objectives, three nozzles were first individually tested, in order to identify the main variables affecting their functioning and performance. Further investigations were then carried out to find the best configuration of nozzles for the final version of the full-scale rainfall simulator and test its performance. Depending on the desired rainfall range, four different configurations of nozzles, distinguished by the number of active nozzles and their location, were chosen to cover the required intensity interval. The simulator performance was assessed via the Christiansen uniformity coefficient (CU), which resulted in values larger than 80%. The drop size distribution was assessed by means of the oil method and used for the calibration of a numerical model aimed at estimating the impact energy of the drops falling onto the soil. This allowed for the assessment of the rainfall potential erosion and its spatial distribution, highlighting that the surface erosion generated by the proposed rainfall simulator is limited, corresponding to the kinetic energy exerted by natural rainfall rates of no more than 10 mm/h
Numerical and physical modeling to assess landslide triggering induced by hydrological hillslope processes
No full textLandslide triggering induced by high-intensity rainfall infiltration in hillslopes is a complex phenomenon that involves hydrological processes operating at different spatio-temporal scales. Empirical methods give useful information about landslide-prone areas and rainfall intensity and duration that generate slope failures, but they do not provide the theoretical framework needed to achieve an in-depth understanding of the involved physical processes. This fact limits the predictive use of these empirical methods, which are usually site-dependent and unable to assess the landslide hazard with respect to different land uses proposed for mitigation purposes. Depending on rainfall intensity, slope geometry, and soil hydraulic properties, the runoff/infiltration process controls water pressure changes in both the saturated and unsaturated zones, affecting the behavior of shear strength and seepage forces, and, as a consequence, the slope stability. In this study, we tackle the whole process by using both numerical and physical approaches, the former being developed to design (a priori) and analyze (a posteriori) a number of experiments carried out in an ad hoc designed artificial hillslope. The maximum height of the embankment, contained in a reinforced concrete box, is 3.5 m, with length of 6 m and width of 2 m, so that a 2:3 slope can be built. On each lateral side of the box, 50 openings closed with screw caps allow the insertion on properly chosen positions of the control instrumentation (6 tensiometers and 6 TDR sensors). The monitoring network, connected to an automatic acquisition system, is completed by two piezometers, one evaporimeter, and two stream gages able to evaluate both the surface runoff and subsurface contributions to the total outflow. The numerical tool we use is a distributed physically-based catchment simulator (CATHY, CATchment Hydrology) able to model both surface routing and subsurface flow in a coupled fashion. In order to demonstrate the effectiveness of the proposed physical and numerical investigation approach, we report on the arrangement of laboratory facilities (including the non-trivial design and building of the rainfall simulator system), the theoretical design of physical experiments, and a preliminary analysis of experimental evidence
Calibration of water content reflectometer sensors with a large soil sample
No full textIn situ measurement of soil water content is of fundamental importance in vadose zone processes. While time domain reflectometry (TDR) is a universally accepted technique, having been developed since the 1980s, water content reflectometer (WCR) is still a relatively new technique and does not hold a similar background. The main goal of this study was to establish an accurate calibration curve for WCR sensors to be installed in an artificial hillslope designed to study the triggering of shallow landslides. Therefore, high accuracy calibration at the high end of the water content range and for large soil volumes was necessary. An experimental device was specifically designed to provide a calibration procedure for a soil control volume commensurate with the application scale of the probes in the hillslope. A large box container (60 by 50 by 60 cm) was used, inside which three WCR probes and three tensiometers were arranged. A drip emitter produced assigned flow rates, while a load cell at the base measured the time evolution of the infiltrated water mass. Water content was evaluated at approximately steady-state flow conditions for infiltration and drainage experiments, performed with varying degrees of compaction to detect the effect of the porosity on the calibration curve. The experimental results suggest a calibration relationship linearly depending not only on the WCR output signal but also on the porosity. In addition, the calibration curve provided by the manufacturer significantly underestimates the soil water content, with a range of predicted volumetric water content values between 3 and 35%, compared with actual values varying between 19 and 61%
Full-scale physical model of landslide triggering
No full textLandslide triggering induced by high-intensity rainfall infiltration in hillslopes is a complex phenomenon that involves hydrological processes operating at different spatio-temporal scales. Empirical methods give rough information about landslide-prone areas, without investigating the theoretical framework needed to achieve an in-depth understanding of the involved physical processes.
In this study, we tackle this issue through physical experiments developed in an artificial hillslope realized in the Department of Civil, Environmental and Architectural Engineering of the University of Padua. The structure consists of a reinforced concrete box containing a soil prism with the following maximum dimensions: 3.5 m high, 6 m long, and 2 m wide. In order to analyze and examine the triggered failure state, the experiments are carried out with intensive monitoring of pore water pressure and moisture content response. Subsurface monitoring instruments are installed at several locations and depths to measure downward infiltration and/or a rising groundwater table. We measure the unsaturated soil water pressure as well as positive pore pressures preceding failure in each experiments with six tensiometers. The volumetric water content is determined through six Time Domain Reflectometry probes. Two pressure transducers are located in observation wells to determine the position of the water table in time. Two stream gauges are positioned at the toeslope, for measuring both runoff and subsurface outflow. All data are collected and recorded by an acquisition data system from Campbell Scientific.
The artificial hillslope is characterized by well-known and controlled conditions, which are designed to reproduce an ideal set-up susceptible to heavy rainfall landslide. The hydrologic forcing is generated by a rainfall simulator realized with nozzles from Sprying System and. specifically designed to produce a spatially uniform rainfall of intensity ranging from 50 to 150 mm/h.
The aim of our experiments is to reproduce the instability trigger that occurs in saturated or partially unsaturated conditions depending on the specific characteristics of the soil and its initial conditions; the retention curve of fine sand and the initial porosity are taken into account to highlight the hydrological condition of the surface layer during the trigger occurrence. Through our experimental setup we can investigate the succession of phases and their magnitude that cause the landslide trigger, in order to understand the instability mechanism that heavy rainfall can induce in fine sandy hillslopes. Particular attention is given on the role of water pressure head, not only with respect to the violation of Coulomb failure within a sloping soil, but also with respect to the subsequent deformation that involves the upper hillslope layers.
In particular, we report here on the characterization of the sandy terrain used in the experiments and the preliminary results, together with a first discussion of the observed data
Problematiche relative all’innesco delle frane superficiali
No full textIl saper riconoscere l’instabilità superficiale dei versanti, dalla quale originano colate detritiche o di fango, spesso comprese nel più generico termine di frane superficiali, risulta determinante nella definizione delle aree soggette a rischio idrogeologico e necessita di studi volti ad inquadrare le dinamiche idrologiche e meccaniche che determinano il collasso. Nella nota sono riportate le prime evidenze delle esperienze svolte su di un pendio strumentato messo a punto per indagare l’innesco di movimenti superficiali conseguenti ad una precipitazione intensa su di un terreno incoerente
Experimental performance evaluation of LoRa wireless links
No full textLAUREA MAGISTRALEAl giorno d'oggi, la comunicazione a lungo raggio con una bassa velocità in bit e un basso consumo energetico ha permesso a LoRa di rivoluzionare la tecnologia IoT (Internet of Things). Le prestazioni di LoRa sono state analizzate per verificare la fattibilità delle applicazioni per interni. Il caso di studio è stato realizzato in uno degli edifici del Politecnico di Milano utilizzando la comunicazione punto-punto. Grazie alla sua convenienza, viene utilizzato Arduino MKR WAN 1300 basato su Atmel SAMD21 e un modulo Lo-Ra Murata CMWX1ZZABZ. I valori sperimentali di RSSI e PER sono stati calcolati e analizzati variando parametri quali potenza di trasmissione, fattore di diffusione e larghezza di banda.Now-a-days, long range communication with low bit rate and low power consumption has enabled LoRa to revolutionize IoT(Internet of Things) technology. LoRa performance was analyzed in to see the viability for Indoor applications. The case study was made in one of the Politecnico di Milano buildings using point-to-point communication. Owing to its cost effectiveness, Arduino MKR WAN 1300 is used which is based on Atmel SAMD21 and a Murata CMWX1ZZABZ Lo-Ra module. Experimental values of RSSI and PER were calculated and analyzed by varying the parameters like transmission power, spreading factor and the bandwidth
Data transferring and analysis with Arduino and LoRa network
No full textLAUREA MAGISTRALELo scopo di questo lavoro è monitorare e ottenere condizioni ambientali come quelle relative
umidità e temperatura di una particolare area usando LoRaWAN. I clienti ottengono il
privilegio di iscriversi agli argomenti di temperatura e / o umidità relativa in cui il MQTT
il broker trasmetterà i dati al mio client Node-RED. Le caratteristiche aggiuntive di questo lavoro
include una lunga durata della batteria e basso costo. Il nodo finale LoRa funziona con una banda ISM a 868 MHz
trasmette i valori al gateway LoRa sul server di rete LoRa. I clienti possono
recuperare le informazioni su qualsiasi periodo desiderato.The aim of this work is to monitor and obtain environmental conditions such as relative
humidity and temperature of a particular area using the LoRaWAN. The clients get the
privilege to subscribe to the temperature and/or relative humidity topics where the MQTT
broker will relay the data to my Node-RED client. The additional features of this work
include long battery life and low cost. The LoRa end node operating at 868 MHz ISM band
transmits the values to the LoRa gateway over the LoRa network server. The clients can
retrieve the information over any desired period
Insights Into Late-Onset Rheumatoid Arthritis (LORA): Characteristics (Clinical and Imaging), Comorbidities, and Therapeutic Targets
No full textLate-onset rheumatoid arthritis (LORA) is defined as rheumatoid arthritis (RA) manifesting after the age of 65 years, although the terminology remains somewhat ambiguous. With the advent of a super-aging society and extended life expectancies, a significant increase in the incidence of LORA is anticipated. In comparison to young-onset RA (YORA), LORA is predominantly characterized by a higher incidence of acute onset, augmented disease activity and constitutional symptoms, a propensity for systemic manifestations, increased erythrocyte sedimentation rate at disease onset, reduced seropositivity, a predilection for involvement of large and proximal joints with symptoms resembling polymyalgia rheumatica, a higher frequency of erosive disease, and a more evenly distributed gender ratio. Elderly individuals, particularly those with multimorbidity and on multiple medications (polypharmacy), are at an elevated risk of developing geriatric syndromes, including sarcopenia and frailty. The response to TNF inhibitors in elderly individuals with RA is generally comparable to that in younger patients, though it may be slightly diminished. The duration of the disease appears to have a more pronounced impact on outcomes than the patient's age. For the management of LORA, it is critical to adopt a patient-specific approach. Non-frail LORA patients who are otherwise aging healthily should receive aggressive treat-to-target management. Conversely, in pre-frail and frail patients, the therapeutic focus should be on averting the progression of irreversible geriatric conditions. The confluence of multimorbidity, polypharmacy, and geriatric syndromes in this patient population necessitates a tailored therapeutic approach to maintain patient autonomy and functional status
np-CECADA: Enhancing Ubiquitous Connectivity of LoRa Networks
No full textLong Range Wide Area Networks (LoRaWAN) offer ubiquitous communications for The Internet of Things (IoT). However, there are many challenges in rolling out LoRaWAN - mainly scalability, energy efficiency, Packet Reception Ratio (PRR), and keeping the channel access as simple as unslotted ALOHA. To this end, we design non-persistent Capture Effect Channel Activity Detection Algorithm (np-CECADA), which is a novel, distributed protocol for the MAC layer of LoRaWAN. It utilizes Channel Activity Detection (CAD), which is a built-in imperfect mechanism for channel sensing and minimal feedback from the gateways. In np-CECADA each device independently adapts backoff times based on the traffic in its vicinity and the transmission power based on the heuristically inferred probability of capturing the channel. To achieve this, first, we carried out an extensive on-field evaluation to measure the effectiveness of CAD and capture effect in LoRa. Using them we designed np CECADA and developed ns-3 modules. Packet Reception Ratio of np-CECADA is 15.74× and 5.13× higher than vanilla LoRaWAN and p-CARMA, respectively. Channel utilization is 11.24× higher compared to LMAC. Further, on a testbed of 30 LoRa devices np-CECADA outperforms LoRaWAN up to 5 times.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.Embedded System
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