Observer-Based Control of Tilting-Pad Thrust Bearings

The active control of hydrodynamic bearings is beginning to receive more attention in the pursuit of lower power losses and reduced maintenance. This paper presents a method by which, from simple measurements, rich information can be deduced from a running bearing that can used to modify the operating parameters of the unit. The bearing is a line-pivot, unidirectional, steadily loaded, directly lubricated tilting pad thrust bearing. This control is achieved by designing an Observer whose inputs include the output measurement(s) from the bearing. The Observer is, in some ways, an inverse model of the bearing (or Plant) that runs in parallel to the bearing and estimates the states of the bearing, such as the applied load, pivot height, minimum film thickness, maximum temperature, effective temperature and power loss. These estimated parameters can then be used in a control algorithm to modify bearing parameters such as inlet temperature or pivot location. It is demonstrated that disturbances in the load on the bearing can be detected simply by measuring a representative temperature in the bearing or changes in pivot height. Appropriate corrective action can then be employed. Whilst only steady-state operation is considered, the method could be developed to study time-varying situations.

Modern gold standard of cardiac output measurement – A simplified bedside measurement of individual oxygen uptake in the cath lab

Objectives Cardiac output (CO) measurements employing the direct Fick principle represent the gold standard in right-sided heart catheterization (RHC). The current widespread approach in hemodynamic workup however uses the indirect Fick principle with assumed values for oxygen uptake (VO2) leading to incorrect CO values in up to 25% of patients. We have tested a contemporary breath-by-breath gas analyzer that allows precise real-time measurements of VO2 with appropriate time and effort to serve the direct Fick principle. Methods By means of a small and mobile metabolic cart assembled with widely used components of a standard spiroergometer, we performed bedside measurements of individual VO2. In 33 unselected, consecutive patients with various indications for RHC we compared CO values derived from indirect vs. direct Fick calculations. Results In 28 of the 33 patients, VO2 measurements were completed with a plausible dataset within a median of 3.2 (interquartile range 2.8–6.2) min. In nine of the 28 patients, CO values based on measured VO2 values differed by more than 20% from CO calculations based on assumed VO2 values with value deviations scattering over a broad range in both directions (maximally +52% to minimally −46%). Conclusions The bedside measurement of VO2 for gold standard CO determination is technically feasible within a few min and can thus be easily included in any RHC protocol. As modern therapy for numerus indications demand a precise upfront measurement of hemodynamics, our method might help to correctly identify patients for costly therapies.

Developing the Test Bench Software for the Technical Inspection of Volumetric Hydraulic Drives

Introduction. The article describes the test bench specialized software, developed for technical inspection of domestic and foreign volumetric hydraulic drives in repair enterprises and service centers. The results of bench tests using a hydraulic bench and software are presented. Materials and Methods For the application software development, G graphical programming language of the Laboratory Virtual Instrumentation Engineering Workbench (Lab- View) programming environment developed by the National Instruments Company has been used. The reliability of the results obtained has been confirmed by a series of bench tests of domestic and foreign volumetric hydraulic drives. Results. There has been developed and implemented new test bench software for the technical inspection of hydraulic drives of different models from domestic and foreign manufacturers in repair plants and service centers. The software is used to capture, process and store data from the sensors during testing, to calculate and output measurement data, to conduct nonlaboratory analysis of the testing process in graphical, textual and video formats, to calibrate sensors, and to store the test results in the electronic library system. The specialized software runs under the Microsoft Windows 7 x86 (32-bit) operating system and is installed on a personal computer of the hydraulic bench data processing unit. The developed software is characterized by the ergonomics of the user interface, the ability to control all the parameters of diagnosing the tested volumetric hydraulic drives. Discussion and Conclusion. Specialized software and the test bench permit high accurate monitoring of all technical condition parameters of the most common domestic and foreign volumetric hydraulic drives in accordance with the requirements of the manufacturers in the repair enterprises and service centers.

Development of Stand-Alone DC Energy Datalogger for Off- Grid PV System Application Based on Microcontroller

This article presents a microcontroller-based direct current (DC) energy data logger developed by adapting low-cost ATmega328 by measuring the PV system DC and voltage characteristics while simultaneously recording the measured value over time to compute the energy production Watt-hour (Wh). The prototype logger has been tested on a live 1 kW standalone PV system where the voltage sensor detects PV series array output voltage ranging between 0–50 VDC by a voltage divider sensing circuit. For accurate sensing of the current output measurement from the PV array, 50A ACS756 hall effect IC was integrated as the current sensor. The data was measured and saved in text format with comma-separated values (CSV) in an SD card, read using Microsoft Excel software. The liquid crystal display (LCD) showed the actual value of the recording process’s current, voltage, power, and duration in minutes. The recorded data has been compared to the standard laboratory digital multimeter for calibration manually to justify the measurement value. The error is minimized to 0.6% average by varying the constant float value in the programming code. The advantage of developing this logger is that the development cost is much cheaper than the standard commercial PV energy meter, can be reproduced for other DC application energy measurements, and easily modify the voltage and current range to suit the application. Apart from that, this logger also provides high accuracy performance, and its independent characteristic is practical for off-grid or off-site PV system use.

Comparison of Cardiac Output Measurement by Electrical Velocimetry with Echocardiography in Extremely Low Birth Weight Neonates

<b><i>Introduction:</i></b> Electrical velocimetry (EV) offers a noninvasive tool for continuous cardiac output (CO) measurements which might facilitate hemodynamic monitoring and targeted therapy in low birth neonates, in whom other methods of CO measurement are not practicably feasible. <b><i>Methods:</i></b> This prospective observational study compared simultaneous cardiac output measurements by electrical velocimetry (CO_EV) with transthoracic echocardiography (CO_TTE) in extremely low birth weight (ELBW) neonates in the neonatal intensive care unit (NICU). Echocardiography was performed by 1 single examiner. Data were analyzed by Bland-Altman analysis and independent-samples analysis of variance. A mean percentage error (MPE) of &#x3c;30% and limits of agreement (LOA) up to ±30% were considered clinically acceptable. <b><i>Results:</i></b> Thirty-eight ELBW neonates were studied and yielded 85 pairs of CO_EV and CO_TTE measurements. Bland-Altman analysis showed an overall bias (the mean difference) and LOA of −126 and −305 to +52 mL min⁻¹, respectively, and an MPE of 66%. Patients with patent ductus arteriosus had a higher bias with LOA and MPE of −166.8, −370.7 to +37 mL min⁻¹, and 69%, respectively. The overall true precision was 58%. <b><i>Conclusion:</i></b> This study showed high bias and lack of agreement between EV and TTE for measurement of CO in ELBW infants in NICU, limiting applicability of EV to monitor absolute values.

Geometric Segmentation of 3D Scanned Surfaces for Multi-Sensor Coordinate Metrology

In modern industry, multi-sensor metrology methods are increasingly applied for fast and accurate 3D data acquisition. These method typically start with fast initial digitization by an optical digitizer, the obtained 3D data is analyzed to extract information to provide guidance for precise re-digitization and multi-sensor data fusion. The raw output measurement data from optical digitizer is dense unsorted points with defects. Therefore a new method of analysis has to be developed to process the data and prepare it for metrological verification. This article presents a novel algorithm to manage measured data from optical systems. A robust edge-points recognition method is proposed to segment edge-points from a 3D point cloud. The remaining point cloud is then divided into different patches by applying the Euclidean distance clustering. A simple RANSAC-based method is used to identify the feature of each segmented data patch and derive the parameters. Subsequently, a special region growing algorithm is designed to refine segment the under-segmentation regions. The proposed method is experimentally validated on various industrial components. Comparisons with state-of-the-art methods indicate that the proposed method for feature surface extraction is feasible and capable of achieving favorable performance and facilitating automation of industrial components.