Method for Monitoring the Stator Core of a Powerful Turbo Generator

The article is devoted to the development of an automatic method and device for monitoring the pressing of the stator core of a powerful turbo generator during its assembling at the manufacturer. The core is assembled and pressed in an upright position in separate parts; at each stage, it is necessary to monitor places with weakened solidity. The unevenness of the compaction density causes a relative displacement of the active steel sheets and losses of iron, as well as the appearance and development of certain defects (loosening of the teeth of the extreme packages, coloring of fragments of the active steel sheets, local closure of the sheets and heating of the packages), which can eventually cause severe accidents and failure of the turbo generator. Existing methods, including automatic ones, do not allow performing reliable monitoring. The method proposed by the authors for detecting places with weakened solidity is based on automatic measurement of the specific pressure of pressing during deformation of special control samples. A device for its implementation has been developed, which is a ring installed on the end surface of the core. Cells with control samples are evenly placed in the ring. The largest decrease in the sample thickness caused by the highest specific pressure corresponds to the smallest defect, and vice versa. As a pressure converter, it is proposed to use a flat metal membrane and a capacitive sensor with a digital output. The characteristics of the converter were calculated and experimentally verified. The specific pressure measurement results were processed using a special electronic unit. The device that has been developed makes it possible to improve labor productivity when monitoring the core, diagnose defects with greater reliability and eliminate them, and, ultimately, increase the reliability of the turbo generator as well as its durability.

Non-eddy-resolving modelling and parametrization of turbulent convection over sea ice leads and evaluation with airborne observations

<p><span><span>The polar ocean regions are characterised by a large variety of interactions between sea ice surfaces</span><span>, open water</span><span>, and the atmosphere. Especially between late autumn and spring, leads (open-water channels in sea ice) may play a crucial role within this system: Due to large temperature differences between the surface of leads and the near-surface atmosphere, strong turbulent convective plumes are generated with an enhanced turbulent transport of heat, moisture, and momentum. In consequence, lead-generated convection has a strong impact on the characteristics of the polar atmospheric boundary layer (ABL). </span></span></p><p><span><span>We apply a plume- but non-eddy-resolving, microscale model to study the convection over three different leads, which had been observed during the aircraft campaign STABLE over the Arctic Marginal Sea Ice Zone in March 2013. Model simulations are performed using a local and a non-local turbulence closure. The latter represents a lead-width-dependent approach for </span><span>the </span><span>turbulent fluxes </span><span>based on large eddy simulation </span><span>and it is</span><span> designed for an idealised, </span><span>lead-perpendicular</span><span>, and near-neutral inflow in an ABL of 300m </span><span>thickness</span><span>. </span><span>The observed cases from STABLE are also characterised by lead-perpendicular inflow conditions</span><span>, but the ABL is much shallower than in the ideali</span><span>s</span><span>ed cases and the inflow stratification is </span><span>partly</span><span> (slightly) stable. </span><span>Our main goal is to study the quality of both parametrizations and to evaluate, if the non-local parametrization shows advantages as compared to the local closure.</span></span></p><p><span><span>We show that the basic</span><span> observed features of the lead-generated convection are represented with both closures </span><span>despite some minor differences that will be explained</span><span>. However, the advantages of the non-local closure become clearly obvious by the physically more realistic representation of regions with observed vertical entrainment or where the observations hint at counter-gradient transport. Moreover, we also show that some weaknesses of the simulations can be </span><span>almost </span><span>overcome by introducing two further modifications </span><span>of</span><span> the non-local closure. We consider our results as another important step in the development of atmospheric turbulence parametrizations </span><span>for </span><span>non-eddy-resolving, microscale simulations of</span><span> strongly inhomogeneous convective </span><span>boundary layers</span><span>.</span></span></p>

Effectiveness of combination endoscopic therapy for colonic anastomotic leaks

Background Colonic anastomotic leaks are associated with significant morbidity and mortality. Whereas small case series suggest that fully covered self-expandable metal stents (FCSEMS) are effective, no larger studies have examined the impact of combination endoscopic therapy on colonic anastomotic leaks. Methods Our retrospective cohort study reviewed 51 patients undergoing endoscopic therapy for colonic anastomotic leaks between 2011 and 2018. Patients receiving combination therapy involving FCSEMS plus local closure (n = 24) were compared with patients receiving FCSEMS alone (n = 18) or endoscopic suturing alone (n = 9). The primary outcomes were technical and clinical success (resolution of leak, removal of percutaneous drains, avoidance of surgical reoperation, and reversal of temporary diversion). Results Clinical success was achieved in 55 % of patients. Clinical success was achieved in 18/24 patients (75 %) with combination therapy compared with 6/18 patients receiving FCSEMS alone (33 %, adjusted risk ratio [RR] 2.16, 95 % confidence interval [CI] 1.10 – 4.24; P = 0.02) and 4 /9 patients undergoing endoscopic suturing alone (44 %, RR 1.91, 95 %CI 0.84 – 4.31; P = 0.10). Stent migration occurred in 40 % of patients. Conclusions This large series demonstrates that combination therapy was associated with a higher rate of clinical success, and future prospective studies are warranted.

Closure coefficients in scale-free complex networks

The formation of triangles in complex networks is an important network property that has received tremendous attention. The formation of triangles is often studied through the clustering coefficient. The closure coefficient or transitivity is another method to measure triadic closure. This statistic measures clustering from the head node of a triangle (instead of from the centre node, as in the often studied clustering coefficient). We perform a first exploratory analysis of the behaviour of the local closure coefficient in two random graph models that create simple networks with power-law degrees: the hidden-variable model and the hyperbolic random graph. We show that the closure coefficient behaves significantly different in these simple random graph models than in the previously studied multigraph models. We also relate the closure coefficient of high-degree vertices to the clustering coefficient and the average nearest neighbour degree.

The vortex gas scaling regime of baroclinic turbulence

The mean state of the atmosphere and ocean is set through a balance between external forcing (radiation, winds, heat and freshwater fluxes) and the emergent turbulence, which transfers energy to dissipative structures. The forcing gives rise to jets in the atmosphere and currents in the ocean, which spontaneously develop turbulent eddies through the baroclinic instability. A critical step in the development of a theory of climate is to properly include the eddy-induced turbulent transport of properties like heat, moisture, and carbon. In the linear stages, baroclinic instability generates flow structures at the Rossby deformation radius, a length scale of order 1,000 km in the atmosphere and 100 km in the ocean, smaller than the planetary scale and the typical extent of ocean basins, respectively. There is, therefore, a separation of scales between the large-scale gradient of properties like temperature and the smaller eddies that advect it randomly, inducing effective diffusion. Numerical solutions show that such scale separation remains in the strongly nonlinear turbulent regime, provided there is sufficient drag at the bottom of the atmosphere and ocean. We compute the scaling laws governing the eddy-driven transport associated with baroclinic turbulence. First, we provide a theoretical underpinning for empirical scaling laws reported in previous studies, for different formulations of the bottom drag law. Second, these scaling laws are shown to provide an important first step toward an accurate local closure to predict the impact of baroclinic turbulence in setting the large-scale temperature profiles in the atmosphere and ocean.

Occlusion at 5 Years of Age Following Hard Palate Closure With Vestibular Flap

Objective: This study aims to assess occlusal relationships and frequency of oronasal fistula at 5 years of age following 2 hard palate closure techniques and to compare results. Design: Retrospective longitudinal study. Setting: Institutional study. Patients: Study patients included 57 patients with nonsyndromic complete unilateral cleft lip and palate who were consecutively treated. All patients underwent our early 2-stage protocol for palatoplasty, which consisted of soft palate plasty at 1 year of age and hard palate closure at 1.5 years of age. Twenty-nine patients underwent hard palate closure using vestibular flap (VF group) technique (2009-2011) and 28 patients underwent conventional hard palate closure with local palatal flap (LPF group) technique (2006-2008). Main Outcome Measures: Occlusal relationships were assessed with 5-year-olds’ index, and frequency of oronasal fistula was investigated. Results: Average 5-year-olds’ index scores for VF and LPF groups were 3.11 and 3.57, respectively ( P < .001). Oronasal fistula occurred in approximately 7% of patients in the VF group and in 18% of patients in the LPF group. Conclusion: Hard palate closure with VF technique may provide better occlusal relationships at 5 years of age than does conventional local closure with the LPF.