Sensorless model-based displacement estimator for piezoelectric actuator through a practical three-stage mechanism.

Piezoelectric elements (PEMs) are used in a variety of applications. In this paper, we developed a new simple sensorless method for a Piezoelectric Actuator (PEA), which includes piezostack elements and a three-stage amplification mechanism. This research focuses on a piezoelectric actuator that incorporates a three-stage amplification system, where the outcome of one stage serves as the input for the subsequent one. The actuator receives two types of inputs: the voltage applied to the piezoelectric elements and the mechanical load it carries. Its output is defined by the rotation angle observed at the end of the third amplification stage. To indirectly measure the actuator's displacement, a basic external circuit is utilized. The precise movement of these actuators is essential. To circumvent the high costs and limitations associated with highly accurate displacement sensors, there has been a growing interest in sensorless control methods. Certain electrical signals, when measured, can provide an estimation of displacement. However, induced voltage measurements are not effective for piezoelectric stacks. Two more promising measures are the voltage and current of the piezoelectric material. Given that the electrical charge on these actuators closely reflects their displacement with minimal hysteresis across a broad frequency spectrum, it's proposed that displacement can be effectively gauged through current measurements that assess charge. The core contribution of this paper is the introduction and validation, both theoretically and experimentally, of a hybrid algorithm that leverages these two electrical signals to enhance the accuracy of displacement estimates. This was confirmed using a laboratory setup. The primary benefit of this research is the presentation of a straightforward sensorless control algorithm, poised for further exploration within the realm of piezoelectric actuators. The simplicity of both the theoretical model and the sensorless technique facilitates their application across a diverse range of piezoelectric actuators and amplification systems, thereby streamlining the design, modeling, and control strategy development for various actuators. The innovation of this study stems from the application of an uncomplicated sensorless estimation algorithm, coupled with a system-level perspective on piezoelectric actuators. This approach utilizes a simple, adaptable model suitable for a wide array of applications and operational techniques.

Inferior turbinate reduction: comparing post-operative bleeding between different surgical techniques.

OBJECTIVE: Post-operative bleeding is one of the most common and severe complications of turbinate surgery. This study compared post-operative bleeding following partial turbinectomy, submucosal turbinate reduction and endoscopic turbinoplasty. METHODS: Post-operative bleeding was assessed in patients who underwent inferior turbinate intervention by partial turbinectomy, submucosal turbinate reduction or endoscopic turbinoplasty between January 2016 and November 2017 and had completed at least one month of follow up. RESULTS: Of 1035 patients who underwent inferior turbinate surgery during the study period, 751 were included. Of these, 56 (7.5 per cent) presented to the emergency room with post-operative bleeding; 31 (8.4 per cent) had undergone partial turbinectomy, 19 (10.7 per cent) had undergone submucosal turbinate reduction and 6 (3.0 per cent) had undergone endoscopic turbinoplasty. The odds ratio of requiring an intervention to control bleeding was significantly lower in the endoscopic turbinoplasty group than in the submucosal turbinate reduction group (odds ratio = 3.26, 95 per cent confidence interval = 1.02-10.43). CONCLUSION: Endoscopic turbinoplasty had the lowest rate of post-operative bleeding and the lowest rate of patients requiring intervention.

System Identification and Mathematical Modeling of A Piezoelectric Actuator through A Practical Three-Stage Mechanism.

Piezoelectric elements (PEMs) are used in a variety of applications. In this paper, we developed a full analytical model and a simple system identification (SI) method of a piezoelectric actuator, which includes piezostack elements and a three-stage amplification mechanism. The model was derived separately for each unit of the system. Next, the units were combined, while taking into account their coupling. The hysteresis phenomenon, which is significant in piezoelectric materials, is described extensively. The theoretical model was verified in a laboratory setup. This setup includes a piezoelectric actuator, measuring devices and an acquisition system. The measured results were compared to the theoretical results. Some of the most well-known forms of system identification are shown briefly, while a new and simple algorithm is described systematically and verified by the model. The main advantage of this work is to provide a solid background and domain knowledge of modelling and system identification methods for further investigations in the field of piezoelectric actuators. Due to their simplicity, both the model and the system identification method can be easily modified in order to be applied to other PEMs or other amplification mechanism methods. The main novelty of this work lies in applying a simple system identification algorithm while using the system-level approach for piezoelectric actuators. Lastly, this review work is concluded and some recommendations for researchers working in this area are presented.

Temporal and spatial aspects of experimental tonic pain: Understanding pain adaptation and intensification.

BACKGROUND: The underlying mechanisms of adaptations to pain are unclear. In order to explore whether central or peripheral mechanisms predominate, the effects of two centrally mediated phenomena - spatial summation of pain (SSP) and transcutaneous electrical nerve stimulation (TENS) - were examined. The effect of the degree of painfulness, rather than absolute stimulation intensity, was also examined. METHODS: Seventeen participants received several series of individually adjusted tonic noxious-heat stimuli (300 s), inducing an initial perceived pain of 2 (mild pain), 4 (moderate pain) and 6 (strong pain) on a visual analogue scale (VAS). The stimuli were administered to small (2.25 cm2) and large (9 cm2) areas to produce SSP and also during TENS treatment, during which 12 VAS ratings were obtained. RESULTS: Adaptation occurred during VAS-2 stimulation and was minimal, followed by intensification during VAS-4 stimulation, whereas VAS-6 stimulation always induced pain intensification. TENS failed to produce analgesia and SSP did not affect adaptation but affected intensification. Stimulation temperatures affected the magnitude of adaptation and intensification within each degree of painfulness. The mathematical models that best fitted the time trend with VAS-2 and VAS-4 were linear, whereas a power function best fitted VAS-6 stimulation. CONCLUSIONS: The mathematical models and the lack of effect of SSP on adaptation suggest that its dominant component is peripheral. Whereas relative painfulness determines whether pain adaptation or intensification occurs (probably a defence mechanism), absolute stimulation intensities influence the magnitude of the effect. Pain intensification is differentially affected by probe size, depending upon the occurrence of initial adaptation.

Variation in quantity and composition of cuticular hydrocarbons in the scorpion Buthus occitanus (Buthidae) in response to acute exposure to desiccation stress.

Scorpions exhibit some of the lowest recorded water loss rates among terrestrial arthropods. Evaporative water loss to the surrounding environment occurs mainly through the integument, and thus its resistance to water loss has paramount significance for the ability of scorpions to tolerate extremely dry habitats. Cuticular hydrocarbons (HCs) deposited on the outer epicuticle play an important role in determining cuticular waterproofing, and seasonal variation in both cuticular HC quantity and composition has been shown to correlate with water loss rates. Precursor incorporation rates into cuticle HCs have been observed to be extremely low in scorpions compared with insects. We therefore used adult male Buthus occitanus (Buthidae) in order to test HC profile plasticity during acute exposure to 14 d and 28 d of experimental desiccation. Cuticular HC profile of hydrated scorpions was similar to that reported for several other scorpion species, consisting of similar fractions of n-alkanes and branched alkanes, with no evidence for unsaturation. Most abundant of the n-alkanes were n-heptacosane (C27; 19±2% of total HCs), n-nonacosane (C29; 16±1%) and n-hentriacontane (C31; 11±1%). Exposure to desiccation stress resulted in a significant increase in the total amount of extracted HCs, and in the relative abundance of branched alkanes at the expense of n-alkanes. Together with an increase in HC chain lengths, these changes mimic previously-reported seasonal variation among freshly-collected specimens. This indicates that scorpions respond to water shortage by regulating the properties of their passive integumental barrier to water loss.

[Vaccinations in sports and recommendations for immunization against flu, hepatitis A and hepatitis B].

Intensive physical training in elite athletes can have an adverse effect on the immune system, and can increase the susceptibility to infectious diseases. The insult to the immune system includes the cellular, humoral and phagocitic pathways. The increased incidence of viral infections (in particularly of the upper respiratory tract) occurs mainly during periods of intense exercise training and competitions due to the combination of physiological and psychological stress. Other factors that may contribute to the decreased immunity and increased susceptibility to infections include eating disorders and nutritional deficiencies, jet lag, sleep deprivation, and lack of proper hygiene in shared food and sleeping quarters. For elite athletes, even a mild viral infection can be devastating due to loss of important training hours and/or compromise of competitive performance. Therefore, in addition to the goal of improving the athletes performance, another important responsibility/obligation of the staff working with athletes (physicians, nutritionists, physiotherapists, and psychologists), is to emphasize preventive medicine and maintenance of good health. In this article we define athletes, and especially elite athletes, as a population at risk of various infections, and recommend immunization against hepatitis A and B and a yearly immunization against influenza.

Mini-dose intrathecal morphine for the relief of post-cesarean section pain: safety, efficacy, and ventilatory responses to carbon dioxide.

To determine the safety, efficacy, and the ventilatory responses to carbon dioxide (CO2) of mini-dose intrathecal morphine, 33 healthy women who underwent cesarean section with spinal anesthesia using 0.75% bupivacaine in 8.25% dextrose were studied. Patients were randomly assigned to receive, in a double-blind fashion, either morphine 0.25 mg (group I, n = 11), morphine 0.1 mg (group II, n = 10), or saline (group III, placebo group, n = 12) in 0.5 ml volume mixed with the bupivacaine. In both groups I and II excellent postoperative analgesia with long duration was obtained (27.7 +/- 4.0 and 18.6 +/- 0.9 hours, respectively, X +/- SEM). All patients in group III required an analgesic (8 mg subcutaneous morphine) within 3 hours of spinal anesthesia. Seven patients in group I and four patients in group II developed mild pruritus that did not require treatment. Ventilatory responses to CO2 showed no evidence of depression attributable to either the 0.25 or 0.1 mg of morphine, but significant depression of the CO2 responses was observed in group III patients after administration of subcutaneous morphine. It is concluded that a dose as low as 0.1 mg of intrathecal morphine gives excellent analgesia with minimal to no side effects and that subcutaneous morphine is associated with marked depression of the ventilatory variables.

Auditory brain-stem evoked potentials to clicks at different presentation rates: estimating maturation of pre-term and full-term neonates.

Auditory brain-stem evoked potentials ABEPs were recorded from 57 neonates ranging in gestational age between 27 and 43 weeks. Averages and standard deviations of I, III and V peak latencies, I-V, I-III and III-V inter-peak latency differences (IPLDs), for 10/sec and 55/sec clicks were calculated for each age group. An additional measure, the net effect of increasing stimulus rate (ISR), was calculated by subtracting 10/sec measures from their 55/sec counterparts. Correlations between ABEP measures and subject age were determined. The results of this study demonstrate a significant correlation between gestational age and electrophysiological measures of peripheral, as well as central, conduction: an inverse correlation between age and peak latencies as well as IPLDs. The slope of this correlation was steeper for the higher stimulus rate. The slope of 55/sec measures vs. age was the sum of the respective slopes of 10/sec measures and of ISR. The maturation of 10/sec measures may reflect white matter development, while ISR changes with gestational age represent maturation of synaptic efficacy. Thus, the maturation of 55/sec measures reflect the combined maturation of nerve conduction velocity and synaptic efficacy along the neonatal auditory nerve and brain-stem. This differential evaluation may enable more accurate determination of developmental age of neonates, with respect to total maturation as well as its constituents.

Comparative reliability of D-xylose absorption and serum beta-carotene measurements in small intestinal disease.

Comparative reliability of D-xylose absorption and serum beta-carotene measurements was studied in 63 healthy and sick children suspected of having proximal small intestinal disease. Group 1 included children with newly diagnosed celiac disease (CD) who were on a normal diet (xylose, n = 46; carotene, n = 43); group 2 included children with CD in remission (xylose, n = 17; carotene, n = 15); group 3 included children with CD in remission, but who were exposed to a gluten-containing diet for an average of 1.4 years (xylose, n = 19; carotene, n = 17); and group 4 included 17 healthy children, insofar as this study is concerned, in whom serum carotene was examined. The means of serum xylose of groups 1 and 3 were significantly lower than the mean of group 2 (p less than 0.001 in both cases). D-Xylose had a sensitivity of 76.9% and a specificity of 100%. The mean serum carotene concentration for group 2 patients with CD in remission was equal to the mean of group 4, which included healthy children. The means of groups 1 and 3 were significantly lower than the means of groups 2 and 4 (p less than 0.001 in all cases). Serum beta-carotene had a sensitivity of 95% and a specificity of 87.5%. The use of these two serum tests in combination would give a specificity of 100% and a sensitivity of 94.1%.(ABSTRACT TRUNCATED AT 250 WORDS)

Pulmonary capillary leak associated with methylmethacrylate during general anesthesia. A case report.

Noncardiogenic pulmonary edema (capillary leak syndrome) developed in a 61-year-old woman after methylmethacrylate was inserted for total hip replacement. The diagnosis was based on the low pulmonary artery and pulmonary artery wedge pressures, low systemic vascular resistance, relative hypovolemia, and clear pulmonary edema. The diagnosis of capillary leak syndrome can be confirmed by the finding of a protein composition of the pulmonary edema approximating that of plasma. The mechanism causing the capillary leak syndrome is unclear, but may be related to hypersensitivity, i.e., a previous hip arthroplasty, or to the release of vasoactive substances. Management consisted of fluid replacement to maintain cardiac output, and mechanical ventilation with positive end expiratory pressure to provide adequate oxygenation.