Embedded AM-FM Signal Decomposition Algorithm for Continuous Human Activity Monitoring

AM-FM decomposition techniques have been successfully used for extracting significative features from a large variety of signals, helping realtime signal monitoring and pattern recognition, since they represent signals as a simultaneous composition of amplitude modulation and frequency modulation, where the carriers, amplitude envelopes, and the instantaneous frequencies are the features to be estimated. Human activities often involve repetitive movements, such as in running or cycling, where sinusoidal AM-FM decompositions of signals have already demonstrated to be useful to extract compact features to aid monitoring, classification, or detection. In this work we thus present the challenges and results of implementing the iterated coherent Hilbert decomposition (ICHD), a particularly effective algorithm to obtain an AM-FM decomposition, within a resource-constrained and low-power ARM Cortex-M4 microcontroller that is present in a wearable sensor we developed. We apply ICHD to the gyroscope data acquired from an inertial measurement unit (IMU) that is present in the sensor. Optimizing the implementation allowed us to achieve real-time performance using less then 16 % of the available CPU time, while consuming only about 5.4 mW of power, which results in a run-time of over 7 days using a small 250 mAh rechargeable cell

Influence of process parameters and alloying type on properties of laser quenched PM-steels

Different alloyed PM steels have been laser quenched in industrial equipment laser diodes (4 kW, controlled by material surface temperature). The aim of this work is to investigate their responses to different process condition and different alloying metals, i.e. Cu, Ni, Mo, Cr and C. Furthermore the microstructure of hardened layer, heat affected zone (HAZ) and bulk zone Pre-alloyed, diffusion bonded and hybrid raw materials have been used. Design of Experiments has been the approach for evaluating the effect of treatment parameters (i.e temperature, spot size and speed) and to develop predictive models, correlating such parameters to hardening depth and scratch hardness number. Results demonstrated which valuable properties could be achieved, even through relatively low alloying. The promising results are encouraging since they allow to forecast a possible positive combination of high local hardness and wear resistance of high precision PM part

Lesson by SARS-CoV-2 disease (COVID-19): whole-body CT angiography detection of "relevant" and "other/incidental" systemic vascular findings

Objectives: Increasing evidence suggests that SARS-CoV-2 infection may lead to severe and multi-site vascular involvement. Our study aimed at assessing the frequency of vascular and extravascular events' distribution in a retrospective cohort of 42 COVID-19 patients. Methods: Patients were evaluated by whole-body CT angiography between March 16 and April 30, 2020. Twenty-three out of the 42 patients evaluated were admitted to the intensive care unit (ICU). Vascular and extravascular findings were categorized into "relevant" or "other/incidental," first referring to the need for immediate patient care and management. Student T-test, Mann-Whitney U test, or Fisher exact test was used to compare study groups, where appropriate. Results: Relevant vascular events were recorded in 71.4% of cases (n = 30). Pulmonary embolism was the most frequent in both ICU and non-ICU cases (56.5% vs. 10.5%, p = 0.002). Ischemic infarctions at several sites such as the gut, spleen, liver, brain, and kidney were detected (n = 20), with multi-site involvement in some cases. Systemic venous thrombosis occurred in 30.9% of cases compared to 7.1% of systemic arterial events, the first being significantly higher in ICU patients (p = 0.002). Among incidental findings, small-sized splanchnic arterial aneurysms were reported in 21.4% of the study population, with no significant differences in ICU and non-ICU patients. Conclusions: Vascular involvement is not negligible in COVID-19 and should be carefully investigated as it may significantly affect disease behavior and prognosis. Key points: • Relevant vascular events were recorded in 71.4% of the study population, with pulmonary embolism being the most frequent event in ICU and non-ICU cases. • Apart from the lung, other organs such as the gut, spleen, liver, brain, and kidneys were involved with episodes of ischemic infarction. Systemic venous and arterial thrombosis occurred in 30.9% and 7.1% of cases, respectively, with venous events being significantly higher in ICU patients (p = 0.002). • Among incidental findings, small-sized splanchnic arterial aneurysms were reported in 21.4% of the whole population

Road traffic pollution and childhood leukemia: a nationwide case-control study in Italy

Background The association of childhood leukemia with traffic pollution was considered in a number of studies from 1989 onwards, with results not entirely consistent and little information regarding subtypes. Aim of the study We used the data of the Italian SETIL case-control on childhood leukemia to explore the risk by leukemia subtypes associated to exposure to vehicular traffic. Methods We included in the analyses 648 cases of childhood leukemia (565 Acute lymphoblastic–ALL and 80 Acute non lymphoblastic-AnLL) and 980 controls. Information on traffic exposure was collected from questionnaire interviews and from the geocoding of house addresses, for all periods of life of the children. Results We observed an increase in risk for AnLL, and at a lower extent for ALL, with indicators of exposure to traffic pollutants. In particular, the risk was associated to the report of closeness of the house to traffic lights and to the passage of trucks (OR: 1.76; 95% CI 1.03–3.01 for ALL and 6.35; 95% CI 2.59–15.6 for AnLL). The association was shown also in the analyses limited to AML and in the stratified analyses and in respect to the house in different period of life. Conclusions Results from the SETIL study provide some support to the association of traffic related exposure and risk for AnLL, but at a lesser extent for ALL. Our conclusion highlights the need for leukemia type specific analyses in future studies. Results support the need of controlling exposure from traffic pollution, even if knowledge is not complete

Comparison - By nanoindentation - Among PM steels obtained from diffusion-bonded powders (nominally equivalent)

In principle, powdered raw materials, produced by a given process and having equal chemical com-position, are supposed to be equivalent. In previous research works, the differences among response to sintering behaviour have been investigated on P/M steels based on four diffusionbonded powders (Fe + Ni + Cu + Mo), with atomized iron base, at the same alloy contents. Two levels of carbon (0.3 and 0.6 wt%) and two sintering conditions have been investigated, in industrial manufacturing conditions. However the comparison of dimensional changes, carbon content, and hardness reveals only modest differences. The comparison of microhardness distribution, fractal analysis, pore features, microstructure patterns show some clear differences, sometimes not univocal. The previously achieved results show that the claimed equivalence is not adequately and completely confirmed by closer and more complete comparative evaluation of experimental data. Only accurate analyses of microhardness and microstructure distributions seem powerful tools to rate, with modest sensitivity, the real similarity of the so claimed equivalent ironbase powders. Clearer differences have been shown by dilatometric analysis. To verify these observed differences, nanoindentation tests have been carried out. Each material has been characterized by nanoindentation measurement, for any process condition. The measured values, plotted on normal distribution graphs, only partially confirm the differences revealed by dilatometry. Some different ranking of diffusion level results from nanoindentation. This recently developed method, suitable to characterize very small volumes of material, appears suitable to find even minor differences among materials that could appear equivalent if evaluated by simpler and easier test methods

Tempra laser di acciai sinterizzati omogenei o disomogenei [Laser hardening of homogeneous and inhomogeneous p/m steels]

An experimental investigation with 4 kW diodes laser system was carried out to study the effects of laser hardening process parameters on properties of P/M steels, based on prealloyed and diffusion-bonded powders. Eight different process parameters have been applied to optimize the process afterwards they have been set to two different compositions. The independent variables investigated have been: surface temperature, T, and laser travel speed (mm/min). The microstructural features of the laser hardened P/M steels were analyzed using LOM and the surface morphology has been characterized by SEM. Hardened depth both via hardness test and via optical measures were evaluated as well and used as responses for the ANOVA of the experimental data gathered. This work reveals the possibility to apply a selective and precise hardening treatment, like Laser Transformation hardening (LHT), to high-property P/M steel parts. Thanks to ANOVA analysis the correlation between energy; density (ED) and optical dimension of treated zone has been identified. By increasing temperature and speed the density energy ED decreases, indeed at high temperature and speed the heated zone is larger. At the same speed, a temperature increase leads to a surface hardness decrease. A similar value of hardness depth (about 0.8 mm) has been detected by means of hardness profiles. The result has been strengthened by scratch test. The parabolic zone presents a very fine martensitic structure on the top of laser trail, and bainite microstructure on transition zone, as literature related. The transition zone between the laser affected zone and the base metal exhibits a micro hardness gradient. It is also possible to notice some Cu diffusion from outer to inner zone. By comparison among LHT specimens and sintering-hardened and stress-relieved one, (characterized by similar chemical compositions) penetration depth and hardness values appear similar. Transformation Hardening (LTH) is a suitable process for producing hard surface, on defined spots of P/M components, through the action of a scanning laser beam. The short heating time enables to decrease part distortion and surface oxidation, in comparison with sinter hardened. The possibility of very selective and precise hardening treatment seems to open new possibilities to widen the use of high-property P/M parts, based on advanced design, for demanding applications

First Multi-Detector Computed Tomography Evidence of Transcatheter Pacing System Migration and Embolization into the Pulmonary Vasculature

: Transcatheter leadless pacemaker dislodgment is a rare and potentially fatal complication of leadless device implantation. We present the first case of multidetector computed tomography images of leadless pacemaker migration and embolization in the pulmonary middle lobe artery. The patient was managed by percutaneous retrieval of the dislodged device and re-implantation in the appropriate position