Design of the absolute position sensors with Hall elements

Práce se zabývá možností použití lineárních Hallových snímačů vyráběných jako integrované obvody pro konstrukci absolutních snímačů polohy a natočení. Hallovy snímače ve spojení s permanentními magnety umožňují rozměrově malou konstrukci. V této práci je popsán návrh a řešení absolutního lineárního snímače polohy pro lineární pohon Stewartovy platformy a absolutních snímačů natočení pro robotický manipulátor Mini-swing. Použití těchto snímačů přináší mnoho výhod, ty hlavní jsou minimální rozměry a vysoká rozlišovací přesnost.This work deals with possibilities of use of linear Hall sensors which are made as integrated circuit for construction of absolute sensors of position and rotary position. Hall sensors with permanent magnets allow a smaller construction. In this work there is described a design and solution of absolute linear sensor of position for linear drive of Stewart's platform and absolute sensors of rotary position for robotic manipulator Mini-swing. Use of these sensors adds many advantages, primary minimal size and high resolution.

Bats and Caves: Activity and Ecology of Bats Wintering in Caves

Temperate regions of the world undergo a marked range of seasonal variation, most becoming extremely cold during the winter. Bats are the only group of vertebrates that have successfully exploited caves as permanent shelter. Although bats may use caves throughout all year, their most important role in ecology of temperate bats is as hibernacula. Here, we summarize various aspects of bat hibernation ecology, including variation in flight activity at the cave entrance; patterns of bat hibernation behaviour; site selection in hibernacula, including the importance of temperature during hibernation; and level of bat movement activity inside the cave. In addition, we review present knowledge on white‐nose syndrome, one of the most important threats to cave‐dwelling bats

Nephrocalcinosis in farmed salmonids: diagnostic challenges associated with low performance and sporadic mortality

Disease conditions that involve multiple predisposing or contributing factors, or manifest as low performance and/or low-level mortality, can pose a diagnostic challenge that requires an interdisciplinary approach. Reaching a diagnosis may also be limited by a lack of available clinical profile parameter reference ranges to discriminate healthy fish from those affected by specific disease conditions. Here, we describe our experience investigating poorly performing rainbow trout (Oncorhynchus mykiss) in an intensive recirculation aquaculture, where reaching a final diagnosis of nephrocalcinosis was not as straightforward as one would wish. To list the issues making the diagnosis difficult, it was necessary to consider the creeping onset of the problem. Further diagnostic steps needed to ensure success included obtaining comparative data for fish blood profiles and water quality from both test and control aquacultural systems, excluding infections with salmonid pathogenic agents and evaluating necropsy findings. Major events in the pathophysiology of nephrocalcinosis could be reconstructed as follows: aquatic environment hyperoxia and hypercapnia RIGHTWARDS ARROW blood hypercapnia RIGHTWARDS ARROW blood acid-base perturbation (respiratory acidosis) RIGHTWARDS ARROW metabolic compensation (blood bicarbonate elevation and kidney phosphate excretion) RIGHTWARDS ARROW a rise in blood pH RIGHTWARDS ARROW calcium phosphate precipitation and deposition in tissues. This case highlights the need to consider the interplay between water quality and fish health when diagnosing fish diseases and reaching causal diagnoses.O

A New Method to Perform Direct Efficiency Measurement and Power Flow Analysis in Vibration Energy Harvesters

Measuring the efficiency of piezo energy harvesters (PEHs) according to the definition constitutes a challenging task. The power consumption is often established in a simplified manner, by ignoring the mechanical losses and focusing exclusively on the mechanical power of the PEH. Generally, the input power is calculated from the PEH’s parameters. To improve the procedure, we have designed a method exploiting a measurement system that can directly establish the definition-based efficiency for different vibration amplitudes, frequencies, and resistance loads. Importantly, the parameters of the PEH need not be known. The input power is determined from the vibration source; therefore, the method is suitable for comparing different types of PEHs. The novel system exhibits a combined absolute uncertainty of less than 0.5% and allows quantifying the losses. The approach was tested with two commercially available PEHs, namely, a lead zirconate titanate (PZT) MIDE PPA-1011 and a polyvinylidene fluoride (PVDF) TE LDTM-028K. To facilitate comparison with the proposed efficiency, we calculated and measured the quantity also by using one of the standard options (simplified efficiency). The standard concept yields higher values, especially in PVDFs. The difference arises from the device’s low stiffness, which produces high displacement that is proportional to the losses. Simultaneously, the insufficient stiffness markedly reduces the PEH’s mechanical power. This effect cannot be detected via the standard techniques. We identified the main sources of loss in the damping of the movement by the surrounding air and thermal losses. The latter source is caused by internal and interlayer friction

Clinical and Laboratory Parameters of Carp Edema Virus Disease: A Case Report

In the present study, we describe a natural outbreak of carp edema virus disease (CEVD) in koi carp, concentrating on clinical manifestation, gross and microscopic pathology, immunological parameters, viral diagnostics, and phylogenetic analysis. Examination of white blood cell parameters showed increased monocyte and decreased lymphocyte counts in CEV-affected fish compared to healthy control fish. Regarding immune system functioning, the present work shows, for the first time, enhanced phagocytic activity in CEV-affected fish. Respiratory burst of phagocytes was strongly increased in diseased fish, the increase being attributed to an increased phagocyte count rather than enhancement of their metabolic activity. The present work also newly shows histopathological changes in the pancreatic tissue of diseased koi.O