Efficient Global Occupancy Mapping for Mobile Robots using OpenVDB

In this work we present a fast occupancy map building approach based on the VDB datastructure. Existing log-odds based occupancy mapping systems are often not able to keep up with the high point densities and framerates of modern sensors. Therefore, we suggest a highly optimized approach based on a modern datastructure coming from a computer graphic background. A multithreaded insertion scheme allows occupancy map building at unprecedented speed. Multiple optimizations allow for a customizable tradeoff between runtime and map quality. We first demonstrate the effectiveness of the approach quantitatively on a set of ablation studies and typical benchmark sets, before we practically demonstrate the system using a legged robot and a UAV.Comment: 6 pages, presented in Agile Robotics Workshop at IROS202

Model Predictive Anti-Surge Control of Centrifugal Compressors with Variable-Speed Drives

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Constrained spectrum control using MPC

Well-known model predictive control (MPC) theory for constrained linear time-invariant (LTI) systems is extended to accommodate hard constraints and cost penalizations on the spectra of the system’s output trajectories. Thus the proposed method facilitates enforcing constraints, and placing weights, on the harmonic content of input-, state- and output-trajectories, in addition to the usual constrained control objectives. The proposed methods are demonstrated by the example problem of reducing torsional vibrations in a drive-shaft

Juvenile mortality in captive lesser kudu (Tragelaphus imberbis) at Basle Zoo and its relation to nutrition and husbandry

Since 1956, when the Basle Zoo (Switzerland) initiated the breeding of lesser kudu (Tragelaphus imberbis), 43% of the lesser kudu juveniles died before reaching an age of 6 mo. In this study, the objective was to obtain the pathological findings, nutritional history, and family tree information in order to evaluate the influence of husbandry on juvenile mortality in these animals. The main cause of death was white muscle disease (WMD), diagnosed in 14 cases (26%) of the deceased juveniles. Although enclosure size had remained constant and animal accessibility to the public was constantly high, both herd size and juvenile mortality had increased from 1956–2004. The diet consumed by the whole group in 2004 had deficient levels of vitamin E and selenium. The increasing linear trend of the mortality rate since the 1960s was significant, and there was a significant correlation between herd size and overall juvenile mortality. In contrast, there was no correlation between herd size and the occurrence of juvenile mortality associated specifically with WMD. Other investigated factors (sex, inbreeding, and season) had no significant effect on overall mortality up to 6 mo of age or on mortality associated with WMD. These results characterize both a dietary and a husbandry problem, and are supported by a lack of similar juvenile mortality in another facility where the diet was supplemented with vitamin E, animal numbers were kept low, and the enclosure structure offered more retreat options for the animals

Studies on CuCe0.75Zr0.25Ox preparation using bacterial cellulose and its application in toluene complete oxidation

A series of CuCe0.75Zr0.25Ox catalysts (CCZ) were synthesized based on the environmental‐friendly bacterial cellulose (BC) by using the sol‐gel method. The corresponding synthesis mechanism, physicochemical properties of the catalysts and catalytic performances for toluene oxidation were comprehensively studied. In the presence of BC without sugar, the CCZ−A synthesized by ethanol‐gel exhibits better catalytic activity than the CCZ−W synthesized by water‐gel, which may be due to the different roles of BC in different solvents. However, it is worth noting that the graft copolymerization between BC and active metal (Ce4+, Cu2+) is the same process in both water‐gel and ethanol‐gel. The activity of CCZ‐SW synthesized by water‐gel using BC with sugar is obviously higher than that of CCZ−W and CCZ−A. The temperature of complete degradation of toluene over CCZ‐SW is 205 °C, which is 35 °C lower than that of CCZ−W. The results from BET, Raman and H2‐TPR indicate that the larger the specific surface area, the more oxygen vacancies and better low‐temperature reducibility, that are mainly responsible for the excellent activity of CCZ‐SW. The existence of sugar in BC could hinder the agglomeration of active metal particles during the calcination process. Combined with the results of in situ DRIFT, the adsorbed toluene on the catalyst surface is oxidized into alkoxide, aldehydic and carboxylic acid species as intermediates before the complete oxidation into CO2 and H2O.

Cervical Artery Dissection and Sports

Cervical artery dissection (CeAD) occurring in the context of sports is a matter of concern for CeAD patients. They seek advice on the role of sports in CeAD and on the safety of resuming sports after CeAD. The scarcity of studies and guidelines addressing these issues poses a challenge. We aimed at summarizing the current knowledge about CeAD and sports in order to provide an informed, comprehensive opinion for counseling CeAD patients. We took into account pathophysiological considerations, observations of cases reports, series, and registries, and conclusions by analogy from aortic dissection or inherited connective tissue syndromes. In summary, practicing active sports as the cause of CeAD seems uncommon. It seems recommendable to refrain from any kind of sports activities for at least 1 month, which can be extended in case of an unfavorable clinical or neurovascular course. We recommend starting with sport activities at low intensity-preferably with types of endurance sports-and to gradually increase the pace in an individually tailored manner, taking into circumstances of the occurrences of the CeAD in the individual patient (particularly in relation to sports), the meaning of sports activities for the individual well-being, the presence or absence of comorbidities and of neurological sequela, neurovascular findings, and whether there are signs of an underlying connective tissue alteration. Major limitations and several forms of bias are acknowledged. Still, in the absence of any better data, the summarized observations and considerations might help clinicians in advising and counseling patients with CeAD in clinical practice