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Journal articles on the topic 'Optical instrument transformer'
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1
Kurosawa, K., S. Yoshida, E. Mori, G. Takahashi, and S. Saito. "Development of an optical instrument transformer for DC voltage measurement." IEEE Transactions on Power Delivery 8, no. 4 (1993): 1721–26. http://dx.doi.org/10.1109/61.248279.
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Christensen, L. H. "Design, construction, and test of a passive optical prototype high voltage instrument transformer." IEEE Transactions on Power Delivery 10, no. 3 (1995): 1332–37. http://dx.doi.org/10.1109/61.400913.
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Cui Xiang and Zhang Guoqiang. "Sensitivity analysis and automatic design of voltage ratio in an optical instrument voltage transformer." IEEE Transactions on Magnetics 35, no. 3 (1999): 1769–72. http://dx.doi.org/10.1109/20.767373.
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Temkina, Valentina, Andrei Medvedev, and Alexey Mayzel. "Research on the Methods and Algorithms Improving the Measurements Precision and Market Competitive Advantages of Fiber Optic Current Sensors." Sensors 20, no. 21 (2020): 5995. http://dx.doi.org/10.3390/s20215995.
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An electromagnetic instrument transformer is a common device used to measure large current values in high-voltage electrical networks; it has been in use for more than a century. However, the optical current transformer, a promising technology also known as a fiber optic current sensor (FOCS), offers increased safety and ease of operation, as well as the absence of errors caused by the magnetic circuit of legacy transformers. Although the FOCS scheme is well known and has been actively developed for over a quarter century, it has certain disadvantages that limit its use. This paper describes the authors’ efforts to solve these problems in order to make FOCS technology competitive and widely adopted. We upgraded the FOCS optical circuit, expanded the frequency band of the captured current signal, and reduced the solution’s cost. We designed new signal processing algorithms to compensate for errors caused by internal factors in the measurement circuit, as well as those caused by environmental influences. We developed an FOCS computer model based on the Jones matrix formalism to enhance the experimental debugging. It allowed us to define the requirements for elements of the optical circuit and its production accuracy.
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Yang, Hong Lei, Shi Bin Liang, Xue Peng Miao, Min Cao, and Ming Chang. "Research and Application of Optical Fiber Sensing Technology on High Voltage Transmission Line Monitoring." Applied Mechanics and Materials 462-463 (November 2013): 59–63. http://dx.doi.org/10.4028/www.scientific.net/amm.462-463.59.
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On-line monitoring of high voltage transmission lines can prevent or reduce the accidents of transmission reduced by icing,wave,breeze vibrations of electric wires and the dropping of electrical insulators.An on-line monitoring system of high voltage transmission lines based on optical fiber sensing technology is setted in this paper.Fiber optic signal demodulation instrument in the transformer substation receives the signal sent by the optical fiber Bragg grating sensors fitted on transmission lines and electric power towers,and then the signal was sent to the transmission line monitoring center by the power system network.Field hang net experiments shows that the system can monitor the high voltage transmission lines accurately for a long time.
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Sawa, T., K. Kurosawa, T. Kaminishi, and T. Yokota. "Development of optical instrument transformers." IEEE Transactions on Power Delivery 5, no. 2 (1990): 884–91. http://dx.doi.org/10.1109/61.53098.
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Bassan, Fabio R., Joao B. Rosolem, Claudio Floridia, et al. "Power-over-Fiber LPIT for Voltage and Current Measurements in the Medium Voltage Distribution Networks." Sensors 21, no. 2 (2021): 547. http://dx.doi.org/10.3390/s21020547.
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In this work, we present the design, laboratory tests, and the field trial results of a power-over-fiber (PoF) low power instrument transformer (LPIT) for voltage and current measurements in the medium voltage distribution networks. The new proposed design of this power-over-fiber LPIT aims to overcome the drawbacks presented by the previous technologies, such as the continuous operation (measuring and data transmission) for a wide current range conducted in the medium voltage transmission lines, damage due to lightning strikes, accuracy dependency on vibration, position and temperatures. The LPIT attends the accuracy criteria of IEC 61869-10 and IEC 61869-11 in terms of current and voltage accuracy and it attends the practical criteria adopted by Utilities companies including voltage measurements without removing the coating of the covered conductors. The PoF based LPIT was developed to be applied at 11.9 kV, 13.8 kV, and 23.0 kV phase-to-phase nominal voltages, and in two current ranges 1.25–30 A and 37.5–900 A. The digital data transmission of current, voltage, and temperature from the sensing unit to the processing unit uses a special synchronism technique and it is performed by two 62.5 µm multimode fibers in 850 nm. The optical powering in 976 nm is also performed by one 62.5 µm multimode fiber from the processing unit to the sensor unit. We presented all details of the sensor design and its laboratory characterization in terms of accuracy and temperature correction. We also presented the results of field tests of the sensor made in two different conditions: in a standard distribution network and an experimental hybrid fiber/power distribution network. We believe that these studies aim to incorporate optical fiber and devices, digital technologies, communications systems in electrical systems driving their evolution.
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Mingotti, Alessandro, Lorenzo Bartolomei, Lorenzo Peretto, and Roberto Tinarelli. "On the Long-Period Accuracy Behavior of Inductive and Low-Power Instrument Transformers." Sensors 20, no. 20 (2020): 5810. http://dx.doi.org/10.3390/s20205810.
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The accuracy evaluation of instrument transformers is always a key task when proper control and management of the power network is required. In particular, accuracy becomes a critical aspect when the grid or the instrumentation itself is operating at conditions different from the rated ones. However, before focusing on the above non-rated conditions, it is important to fully understand the instrument transformer behavior at rated conditions. To this end, this work analyzed the accuracy behavior of legacy, inductive, and low-power voltage transformers over long periods of time. The aim was to find patterns and correlations that may be of help during the modelling or the output prediction of voltage transformers. From the results, the main differences between low-power and inductive voltage transformers were pointed out and described in detail.
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Cundeva-Blajer, Marija. "Application of optimization methods for improved electrical metrology." ACTA IMEKO 5, no. 3 (2016): 9. http://dx.doi.org/10.21014/acta_imeko.v5i3.378.
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<p class="Abstract"><span lang="EN-US">In electrical quantities metrology numerous examples of stochastic processes exist and a need for optimal solutions is posed. Here stochastic genetic algorithm optimization is used for solving two typical metrological problems: 1) minimization of the metrological parameters (final accuracy) in the design process of instruments and 2) predicting metrological reference standard’s time-drift, i.e. re-calibration interval. The first case is the optimal metrological design of a combined instrument transformer and the second case is the analysis of resistance standard time-drift.</span></p>
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Mingotti, Alessandro, Lorenzo Peretto, Lorenzo Bartolomei, Diego Cavaliere, and Roberto Tinarelli. "Are Inductive Current Transformers Performance Really Affected by Actual Distorted Network Conditions? An Experimental Case Study." Sensors 20, no. 3 (2020): 927. http://dx.doi.org/10.3390/s20030927.
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The aim of this work is to assess whether actual distorted conditions of the network are really affecting the accuracy of inductive current transformers. The study started from the need to evaluate the accuracy performance of inductive current transformers in off-nominal conditions, and to improve the related standards. In fact, standards do not provide a uniform set of distorted waveforms to be applied on inductive or low-power instrument transformers. Moreover, there is no agreement yet, among the experts, about how to evaluate the uncertainty of the instrument transformer when the operating conditions are different from the rated ones. To this purpose, the authors collected currents from the power network and injected them into two off-the-shelf current transformers. Then, their accuracy performances have been evaluated by means of the well-known composite error index and an approximated version of it. The obtained results show that under realistic non-rated conditions of the network, the tested transformers show a very good behavior considering their nonlinear nature, arising the question in the title. A secondary result is that the use of the composite error should be more and more supported by the standards, considering its effectiveness in the accuracy evaluation of instrument transformers for measuring purposes.
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van der Krift, Theo, Ulrike Ziese, Willie Geerts, and Bram Koster. "Computer-Controlled Transmission Electron Microscopy: Automated Tomography." Microscopy and Microanalysis 7, S2 (2001): 968–69. http://dx.doi.org/10.1017/s1431927600030919.
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The integration of computers and transmission electron microscopes (TEM) in combination with the availability of computer networks evolves in various fields of computer-controlled electron microscopy. Three layers can be discriminated: control of electron-optical elements in the column, automation of specific microscope operation procedures and display of user interfaces. The first layer of development concerns the computer-control of the optical elements of the transmission electron microscope (TEM). Most of the TEM manufacturers have transformed their optical instruments into computer-controlled image capturing devices. Nowadays, the required controls for the currents through lenses and coils of the optical column can be accessed by computer software. The second layer of development is aimed toward further automation of instrument operation. For specific microscope applications, dedicated automated microscope-control procedures are carried out. in this paper, we will discuss our ongoing efforts on this second level towards fully automated electron tomography. The third layer of development concerns virtual- or telemicroscopy. Most telemicroscopy applications duplicate the computer-screen (with accessory controls) at the microscope-site to a computer-screen at another site. This approach allows sharing of equipment, monitoring of instruments by supervisors, as well as collaboration between experts at remote locations.Electron tomography is a three-dimensional (3D) imaging method with transmission electron microscopy (TEM) that provides high-resolution 3D images of structural arrangements. with electron tomography a series of images is acquired of a sample that is tilted over a large angular range (±70°) with small angular tilt increments.
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Li, Qian, Samuel D. Marks, Sunil Bean, et al. "Simultaneous scanning near-field optical and X-ray diffraction microscopy for correlative nanoscale structure–property characterization." Journal of Synchrotron Radiation 26, no. 5 (2019): 1790–96. http://dx.doi.org/10.1107/s1600577519008609.
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A multimodal imaging instrument has been developed that integrates scanning near-field optical microscopy with nanofocused synchrotron X-ray diffraction imaging. The instrument allows for the simultaneous nanoscale characterization of electronic/near-field optical properties of materials together with their crystallographic structure, facilitating the investigation of local structure–property relationships. The design, implementation and operating procedures of this instrument are reported. The scientific capabilities are demonstrated in a proof-of-principle study of the insulator–metal phase transition in samarium sulfide (SmS) single crystals induced by applying mechanical pressure via a scanning tip. The multimodal imaging of an in situ tip-written region shows that the near-field optical reflectivity can be correlated with the heterogeneously transformed structure of the near-surface region of the crystal.
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Cundeva, Marija, Ljupco Arsov, and Goga Cvetkovski. "Genetic algorithm coupled with FEM‐3D for metrological optimal design of combined current‐voltage instrument transformer." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 23, no. 3 (2004): 670–76. http://dx.doi.org/10.1108/03321640410540584.
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Liu, Chen Yao, and Kuo Bin Liu. "Design and Modeling of Anisolationstep-Down Transformer by Piezoelectric Material." Applied Mechanics and Materials 431 (October 2013): 231–36. http://dx.doi.org/10.4028/www.scientific.net/amm.431.231.
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The energy conversion and the step-down voltage waveform of apiezo transformer are required to achieve an optimal working condition of the resonant frequency. To fulfill this requirement, a reliable and precise instrument is needed to scan the resonant point of the piezo transformer such that its output power performance can conform to the required specification. This paper describes the design and modeling of a new step-down piezo transformer deployed in NSRRC. This transformer is capable of delivering energy conversion with a highly efficient performance, better than that of a traditional transformer, and the voltage transfer ratio is correct. Use ofa simulation circuit model to develop its driver circuit is included in the design of this new step-down transformer. It has been tested and proved to work satisfactorily in power conversion with excellent efficiency and reliability.
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Mortazavi, Seyed Hossein. "Satellite optical misalignment test procedure subject to theodolites." Aircraft Engineering and Aerospace Technology 89, no. 1 (2017): 176–83. http://dx.doi.org/10.1108/aeat-10-2014-0179.
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Purpose The purpose of this study is to address the concept and the step-by-step procedure of a high-precision optical alignment test for spacecrafts using digital theodolites. The proposed scheme focuses on the non-contact alignment qualification of spacecraft components during the integration and test phases until the launch event. Design/methodology/approach The proposed approach is based on the exploitation of the auto-collimation feature of theodolites and several prisms attached to the requested component and satellite configuration. As soon as the misalignment measurement including the difference between the real and desired attitude or position aberration of an instrument is made, the results must be transformed from the component level to the system level for misalignment error identification in the spacecraft dynamic model. Findings The paper introduces the main instruments, the defined coordinate systems and the architecture of the optical spacecraft misalignment test. Moreover, the guideline of the test implementation and the resulting data process have been presented carefully. Research limitations/implications There is no limitation associated with this method because the procedure is applicable for high-precision typical missions. Practical implications This paper describes a fully implementable scheme to examine any possible inaccuracy in mounting of the spacecraft components both in position and orientation. The test can be performed without the need for a huge budget or complicated hardwares. Originality/value The contribution of this work revolves around illustrating the context and procedure of the spacecraft misalignment test which has remained unknown in literature despite the frequent implementation in the different satellite projects.
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Mitsakakis, Nicholas, Karen E. Bremner, George Tomlinson, and Murray Krahn. "Exploring the Benefits of Transformations in Health Utility Mapping." Medical Decision Making 40, no. 2 (2020): 183–97. http://dx.doi.org/10.1177/0272989x19896567.
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Background. Quality-of-life research and cost-effectiveness analyses frequently require data on health utility, a global measure of health-related quality of life. When utilities are unavailable, researchers have “mapped” descriptive instruments to utility instruments, using samples of responses to both instruments. Health utilities have an idiosyncratic distribution, with upper bound and probability mass at 1, left skewness, and kurtosis. Estimation of mean utility values conditional on covariates is of interest, particularly in health utility mapping applications. Traditional linear regression may be unsuitable because fundamental assumptions are violated. Complex statistical methods come with deficiencies that may outweigh their benefits. Aim. To investigate the benefits of transforming the health utility response variable before fitting a linear regression model. Methods. We compared log, logit, arcsin, and Box-Cox transformations with an untransformed model, using several measures of model accuracy. We made our evaluation by designing and conducting a simulation study and reanalyzing data from 2 published studies, which “mapped” a psychometric descriptive instrument to a utility instrument. Results. In the simulation study, log transformation with smearing estimator had in most cases the lowest bias but one of the highest variances, especially for estimating low utility values under small sample size. The untransformed model was outperformed by the transformed models. Findings were inconclusive for the analysis of real data, where arcsin gave the lowest error for one of the data sets, while the untransformed model had the best performance for the other. Conclusions. We identified the benefits of transformations and offered suggestions for future modeling of health utilities. However, the benefits were moderate and no single transformation appeared to be universally optimal, suggesting that selection requires examination on a case-by-case basis.
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Jaschke, Christian, and Peter Schegner. "Computing the Coupling Resistances in High-Current Instrument Transformers Considering Skin and Proximity Effect." IEEE Transactions on Magnetics 53, no. 11 (2017): 1–7. http://dx.doi.org/10.1109/tmag.2017.2718239.
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Mingotti, Alessandro, Lorenzo Peretto, and Roberto Tinarelli. "Toward the Standardization of Limits to Offset and Noise in Electronic Instrument Transformers." Sensors 20, no. 14 (2020): 4061. http://dx.doi.org/10.3390/s20144061.
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The scenario of instrument transformers has radically changed from the introduction of the Low-Power version, both passive and active. The latter type, typically referred to as Electronic Instrument Transformers (EITs), has no dedicated standard within the IEC 61869 series yet. To this purpose, in the authors’ opinion, it is worth understanding how the limits of typical disturbances affecting EITs should be standardized. In particular, after a brief review of the standards, the work presented a mathematical approach to determine the sources of signal disturbances influence, which affect the rms value, on the ratio error. From the results, we discussed that the emergence of disturbances generated within the EIT is a critical aspect to be studied with data of typical off-the-shelf devices. Therefore, to guarantee a correct operation of the devices, a proper standardization of the sources of disturbance should be provided.
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Cundeva-Blajer, Marija, and Ljupco Arsov. "FEM-3D electromagnetic field analysis coupled with genetic algorithm for measurement uncertainties estimation and optimal design of an instrument transformer." International Journal of Applied Electromagnetics and Mechanics 28, no. 1-2 (2008): 25–31. http://dx.doi.org/10.3233/jae-2008-952.
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Pytlech, Robert. "Mixed D-Core With a Distributed Air Gap as an Alternative for Medium Voltage Instrument Transformers." IEEE Transactions on Magnetics 46, no. 10 (2010): 3816–25. http://dx.doi.org/10.1109/tmag.2010.2049855.
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Ghaderi, Abbas, Alessandro Mingotti, Lorenzo Peretto, and Roberto Tinarelli. "Low-Power Voltage Transformer Smart Frequency Modeling and Output Prediction up to 2.5 kHz, Using Sinc-Response Approach." Sensors 20, no. 17 (2020): 4889. http://dx.doi.org/10.3390/s20174889.
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The instrument transformers scenario is moving towards the adoption of a new generation of low-power instrument transformers. This disruptive change also requires that the modeling, characterization, and testing of those devices must be improved. Therefore, this study focuses on a smart approach developed by the authors in a previous study to estimate the output of low-power voltage transformers (LPVT). The approach—which is based on a sort of modeling in the frequency domain (the so-called sinc-response)—allows obtaining the behavior of the LPVT at rated and distorted conditions. Experimental tests performed on off-the-shelf devices confirm the applicability and effectiveness of the proposed approach when estimating the output response of LPVTs.
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Mingotti, Alessandro, Lorenzo Peretto, and Roberto Tinarelli. "Smart Characterization of Rogowski Coils by Using a Synthetized Signal." Sensors 20, no. 12 (2020): 3359. http://dx.doi.org/10.3390/s20123359.
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With the spread of new Low-Power Instrument Transformers (LPITs), it is fundamental to provide models and characterization procedures to estimate and even predict the LPITs’ behavior. In fact, distribution system operators and designers of network models are looking for all forms of information which may help the management and the control of power networks. For this purpose, the paper wants to contribute to the scientific community presenting a smart characterization procedure which easily provides sufficient information to predict the output signal of a Low-Power Current Transformer (LPCT), the Rogowski coil. The presented procedure is based on a synthetized signal applied to the Rogowski coil. Afterwards, the validity of the procedure is assessed within the Matlab environment and then by applying it on three off-the-shelf Rogowski coils. Simulations and experimental tests and results involving a variety of distorted signals in the power quality frequency range and by adopting a quite simple measurement setup demonstrated the effectiveness and the capability of the procedure to correctly estimate the output of the tested device.
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Nezami, Md Manzar, Md Danish Equbal, Shakeb A. Khan, Shiraz Sohail, and Sherif S. M. Ghoneim. "Classification of Cellulosic Insulation State Based on Smart Life Prediction Approach (SLPA)." Processes 9, no. 6 (2021): 981. http://dx.doi.org/10.3390/pr9060981.
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The state of cellulosic solid kraft paper (CSKP) insulation, to a large extent, is an indication of a transformer’s health. It not only reflects the condition of transformer but also diagnose its residual life. The quantity of 2-furfuraldehyde (2-FAL), carbon dioxide (CO2), and carbon monoxide (CO) dissolved in the transformer oil are useful diagnostic indicators to predict the state of the CSKP insulation. In this work, the current physical state of the CSKP is determined with the help of easily measurable parameters, like temperature, moisture, and the aging time. Here, the degree of deterioration of CSKP insulation has been determined using an integrated insulation health assessment system. This technique integrates a two-stage system comprising of a neural network (NN) model followed by a Smart Life Prediction Approach (SLPA). A thermo-moisture-aging multi-layer feed-forward NN model has been developed to predict the concentrations of 2-FAL, CO2, and CO, which are further correlated to estimate the Degree of Polymerization (DP) values adopting an SLPA. The advantage of the proposed integrated system is that it provides an alternative means of paper health assessment based on Dissolved Gas Analysis (DGA) without estimating dissolved gas concentrations in oil, thereby avoiding the use of sophisticated measuring instruments. The optimal configuration of the NN model has been achieved at minimum iterations with an average cross-validation mean square error of 3.78 × 10−7. The proposed system thereby avoids destructive and offline measurement of DP and facilitates real-time condition monitoring of oil-immersed transformers. The test results of the developed system show considerable reliability in determining insulation health using easily measurable parameters. Furthermore, the system’s performance is compared with reported work and has been found to provide encouraging outcomes.
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Martínez, Ana María, Paula Giudici, Alicia Beatriz Trigubó, et al. "Crystalline Quality, Composition Homogeneity, Tellurium Precipitates/Inclusions Concentration, Optical Transmission, and Energy Band Gap of Bridgman Grown Single-Crystalline Cd1−xZnxTe (0 ≤ x ≤ 0.1)." Materials 14, no. 15 (2021): 4207. http://dx.doi.org/10.3390/ma14154207.
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Cd1−xZnxTe (0 ≤ x ≤ 0.1) ingots were obtained by Bridgman’s method using two different speeds in order to find the optimal conditions for single-crystalline growth. Crystalline quality was studied by chemical etching, the elemental composition by wavelength dispersive spectroscopy (WDS), tellurium (Te) precipitates/inclusions concentration by differential scanning calorimetry (DSC), optical transmission by Fourier transformed infrared spectrometry (FTIR), and band gap energy (Egap) by photoluminescence (PL). It was observed that the ingots grown at a lower speed were those of the best crystalline quality, having at most three grains of different crystallographic orientation. The average dislocations density in all of them were similar and correspond to materials of good quality. EPMA results indicated that the homogeneity in the composition was excellent in the ingots central part. The concentration of Te precipitates/inclusions in all ingots was below the instrument (DSC) detection limit, 0.25% wt/wt. In the case of wafers from Cd0.96Zn0.04Te and Cd0.90Zn0.10Te ingots, the optical transmission was better than that of commercial materials and varied between 60% and 70%, while for pure CdTe, the transmission range was between 50% and 55%, the latter being decreased by the presence of Te precipitates/inclusions. The band gap energy Eg of different wafers was experimentally obtained by PL measurements at 76 K. We observed that Eg increased with the Zn concentration of the wafers, following a linear regression comparable to those proposed in the literature, and consistent with the results obtained with other techniques.
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Artale, Giovanni, Giuseppe Caravello, Antonio Cataliotti, et al. "PQ and Harmonic Assessment Issues on Low-Cost Smart Metering Platforms: A Case Study." Sensors 20, no. 21 (2020): 6361. http://dx.doi.org/10.3390/s20216361.
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This paper presents a feasibility study on how to implement power quality (PQ) metrics in a low-cost smart metering platform. The study is aimed at verifying the possibility of implementing PQ monitoring in distribution networks without replacing existing smart metering devices or adding new modules for PQ measurements, thus zeroing the installation costs. To this aim, an electronic board, currently used for remote energy metering, was chosen as a case study, specifically the STCOMET platform. Starting from the specifications of this device, the possibility of implementing power quality metrics is investigated in order to verify if compliance with standard requirements for PQ instruments can be obtained. Issues related to device features constraints are discussed; possible solutions and correction algorithms are presented and experimentally verified for different PQ metrics with a particular focus on harmonic analysis. The feasibility study takes into account both the use of on-board voltage and current transducers for low voltage applications and also the impact of external instrument transformers on measurement results.
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Mingotti, Alessandro, Federica Costa, Gaetano Pasini, Lorenzo Peretto, and Roberto Tinarelli. "Modeling Capacitive Low-Power Voltage Transformer Behavior over Temperature and Frequency." Sensors 21, no. 5 (2021): 1719. http://dx.doi.org/10.3390/s21051719.
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The use of capacitive dividers (CDs) in medium-voltage (MV) networks started as simple voltage detectors and as rough voltage measurement instruments for protective purposes. Now, with the spread of intelligent electronic devices and renewable energy sources at the distribution level, capacitive dividers are designed and installed to perform accurate voltage measurements. Such a requirement is mandatory when the power quality has to be assessed. Therefore, CDs are currently being used either for power frequency or for high-frequency (supraharmonic- or partial-discharge-level) measurements. In this paper, typical off-the-shelf CDs are studied and modeled to understand how they behave in a wide range of frequencies and when the temperature varies. To this purpose, specific setups and tests have been developed and performed. From the results, it is clear that with proper modeling of CDs, it is possible to exploit them for measuring phenomena in a wide range of frequencies, including the effects due to temperature variations and self-resonances.
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Hutao, Cui, Cheng Xiaojun, Xu Rui, and Cui Pingyuan. "RHC‐based attitude control of spacecraft under geometric constraints." Aircraft Engineering and Aerospace Technology 83, no. 5 (2011): 296–305. http://dx.doi.org/10.1108/00022661111159906.
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PurposeThe purpose of this paper is to propose an attitude control algorithm for spacecraft with geometric constraints.Design/methodology/approachThe geometric constraint is reformulated as a quadratic form when quaternion is used as attitude parameter, then the constraint is proved to be nonconvex and is further transformed to a convex one. By designing a new constraint formulation to satisfy the real constraint in the predictive horizon, the attitude control problem is reshaped to a convex planning problem which is based on receding horizon control.FindingsThe proposed algorithm is more effective in handling geometric constraints than previous research which used single step planning control.Practical implicationsWith novel improvements to current methods for steering spacecraft from one attitude to another with geometric constraints, great attitude maneuver path can be achieved to protect instruments and meanwhile satisfy mission requirements.Originality/valueThe attitude control algorithm in this paper is designed especially for the satisfaction of geometric constraints in the process of attitude maneuver of spacecraft. By the application of this algorithm, the security of certain optical instruments, which is critical in an autonomous system, can be further assured.
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Yershov, V. N. "A Giant Meridian Circle - Reflector." Symposium - International Astronomical Union 166 (1995): 360. http://dx.doi.org/10.1017/s007418090022843x.
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A 1.5 m reflector is proposed for infrared and optical meridian observations in order to extend the fundamental coordinate system to faintest objects and to the K-infrared waveband. Classical meridian circles are unfit for the infrared observations because their lens objectives do not give good images in the infrared. But reflectors are almost never used as meridian circles due to uncertainties in their optical axis position. The main problem is that the secondary mirror is not connected with the micrometer and the circle reading system. In order to overcome this difficulty the author proposes to use an intermediary focal plane between the primary and the secondary mirrors where a luminous reference grid of wires might be placed. The Gregory optical scheme has such a focal plane, and its secondary mirror forms images of a star and the grid at the micrometer's detecting area. At the same time a special champher around the primary's central hole forms anautocollimated image of the grid near the grid itself. The micrometer measures the star image coordinates relative to two images of the reference grid. So, observations will not be affected by displacements of the secondary mirror and by those of the micrometer. The telescope's equivalent focal length has been chosen as 3 m, and the optical system has been transformed into an aplanatic Mersenne combined with an aplanatic focal reducer corrector (Popov, 1988). A new autocollimated circle reading system is chosen for the instrument (Yershov and Nemiro, 1994). The observations will be linked to the fixed optical axis of two long-focus collimators placed at the prime vertical plane.
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Vu, Ngoc Dan, Alina Vyacheslavovna Taneeva, and Vyacheslav Fedorovich Novikov. "Improvement of the gas chromatographic method for diagnosing developing defects in oil-filled electrical equipment based on the analysis of furan compounds." E3S Web of Conferences 288 (2021): 01080. http://dx.doi.org/10.1051/e3sconf/202128801080.
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During the operation of oil-filled electrical equipment under the influence of temperature, humidity and other negative factors, the destruction of paper insulation occurs. As a result of this destruction, furan compounds are formed, which get into the transformer oil. To identify the process of destruction of paper insulation, control of furan compounds in transformer oil is carried out by instrumental methods. Of these methods, the most widely used is gas chromatography using packed chromatographic columns, on the basis of which guidelines have been developed. To improve gas chromatographic methods for monitoring furan compounds, we used a highly efficient quartz capillary column filled with a polar stationary phase based on polyethylene glycol. The sample was injected into the injector of the chromatograph Chromos-GC1000 using an automated dosing system with a vial for 23 samples. Used transformer oil of the GK-1 brand of Almetyevsk electrical networks was taken as the object of research; The optimal retention characteristics of standard sorbates were preliminary determined, which were used as organic extractants of transformer oil and furan compounds. The effect of temperature on the process of chromatographic analysis of furfuryl alcohol and organic extractants was determined, on the basis of which it was established that the selectivity of separation is determined by the nature of intermolecular interactions in the sorbate-sorbent system, in particular, the formation of a hydrogen bond. It has been shown that the selectivity coefficient for the separation of furfuryl alcohol depends on the physicochemical nature of organic extractants, their boiling points and dipole moments and has the highest values for the analyzed pair of components: furfuryl alcohol - ethanol.
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Goswami, Arti Grover, and Somik V. Lall. "Jobs and Land Use within Cities: A Survey of Theory, Evidence, and Policy." World Bank Research Observer 34, no. 2 (2019): 198–238. http://dx.doi.org/10.1093/wbro/lkz004.
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Abstract Over the last century, the urban spatial structure of cities has transformed dramatically from a traditional monocentric configuration to varying forms of decentralized organization. This paper reviews theory and empirical evidence to understand the urban morphology of jobs and land use within a city. Our survey highlights four broad insights: (i) The evolution of monocentric to polycentric centers have been accompanied by structural changes within the city. (ii) The internal geography of a city is an outcome of the trade-off between the pull from agglomeration economies and the push from congestion. (iii) The presence of externalities implies that the equilibrium spatial organization achieved by profit-maximizing firms may not necessarily be optimal. This justifies the role of public policy in addressing associated market failures. (iv) The productive edge and competitiveness of a city can be enhanced by introducing policies that increase the overall connectivity to take advantage of economic opportunities across the metropolitan area. The survey also puts together a wide range of policy instruments useful in closing the gap between equilibrium urban spatial structures and the optimal outcome.
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Paek, Sung Wook, Sivagaminathan Balasubramanian, Sangtae Kim, and Olivier de Weck. "Small-Satellite Synthetic Aperture Radar for Continuous Global Biospheric Monitoring: A Review." Remote Sensing 12, no. 16 (2020): 2546. http://dx.doi.org/10.3390/rs12162546.
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Space-based radar sensors have transformed Earth observation since their first use by Seasat in 1978. Radar instruments are less affected by daylight or weather conditions than optical counterparts, suitable for continually monitoring the global biosphere. The current trends in synthetic aperture radar (SAR) platform design are distinct from traditional approaches in that miniaturized satellites carrying SAR are launched in multiples to form a SAR constellation. A systems engineering perspective is presented in this paper to track the transitioning of space-based SAR platforms from large satellites to small satellites. Technological advances therein are analyzed in terms of subsystem components, standalone satellites, and satellite constellations. The availability of commercial satellite constellations, ground stations, and launch services together enable real-time SAR observations with unprecedented details, which will help reveal the global biomass and their changes owing to anthropogenic drivers. The possible roles of small satellites in global biospheric monitoring and the subsequent research areas are also discussed.
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Avdeyev, Boris Aleksandrovich, and Alexei Viktorovich Vyngra. "Examining efficient treatment of parts during ship repair with cutting fluids cleaning in magnetic sump." Vestnik of Astrakhan State Technical University. Series: Marine engineering and technologies 2020, no. 2 (2020): 22–29. http://dx.doi.org/10.24143/2073-1574-2020-2-22-29.
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The article considers the problem of cleaning efficiency of cutting fluids used in the technological processes of parts treatment during ship repair. One of the cleaning instruments is a magnetic sump which has a high efficiency at a relatively low cost of operation and maintenance. The laboratory tests of the magnetic sump were carried out using a full-factor experiment, with changing certain parameters in order to identify the coolant purity index when cleaning from mechanical impurities. The dependencies are obtained that connect the value of the coolant purity index with the technological and construction parameters of the magnetic sump. The influence of the coolant purity index in the magnetic sump on the roughness of the polished surface of the samples was revealed. With a decreasing concentration of solids after cleaning in a magnetic sump, the surface roughness parameter of the samples decreases from 0.8 to 0.2 μm. The most rational parameters of the magnetic sump have been determined, at which the optimal surface roughness is observed when processing the engine crankshaft using coolant cleaned in a magnetic sump. The scheme of the experimental facility has been presented to determine the efficiency of cleaning the cutting fluid from the mechanical impurities in a magnetic sump, which includes a LATR adjustment transformer, a 220 / 12V step-down transformer, a voltmeter, an ammeter, a rectifier diode unit, and a magnetic sump. It has been stated that the errors of the presented experimental and calculated dependences did not exceed 10%. It has been inferred that cleaning the cutting fluid in the magnetic sump to maximum values allows increasing the intervals of machine time between cleaning the circle up to 70%.
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Mingotti, Alessandro, Lorenzo Peretto, and Roberto Tinarelli. "A Closed-form Expression to Estimate the Uncertainty of THD Starting from the LPIT Accuracy Class." Sensors 20, no. 6 (2020): 1804. http://dx.doi.org/10.3390/s20061804.
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Power quality is a wide-ranging and current topic that involves a huge effort from the scientific community. Power quality issues have to be avoided or solved in order to preserve the integrity of the network and its assets. To this purpose, several power quality indexes and measurement techniques have been developed and used by experts. This paper aims at solving the issue of having an uncertainty associated to the total harmonic distortion (THD) measurements. The idea is to obtain a close-form expression, which only requires the knowledge of the instrument transformer accuracy class, to estimate the mean value and the variance of THD. After the development of such an expression, it has been tested and stressed to confirm its effectiveness and applicability in a variety of conditions, and for harmonics up to 25th (of 50 Hz), defined by the standards.
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Jordan, Carolyn E., Ryan M. Stauffer, Brian T. Lamb, et al. "New in situ aerosol hyperspectral optical measurements over 300–700 nm – Part 1: Spectral Aerosol Extinction (SpEx) instrument field validation during the KORUS-OC cruise." Atmospheric Measurement Techniques 14, no. 1 (2021): 695–713. http://dx.doi.org/10.5194/amt-14-695-2021.
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Abstract. In situ observations of spectrally resolved aerosol extinction coefficients (300–700 nm at ∼ 0.8 nm resolution) from the May–June 2016 Korea–United States Ocean Color (KORUS-OC) oceanographic field campaign are reported. Measurements were made with the custom-built Spectral Aerosol Extinction (SpEx) instrument that previously has been characterized only using laboratory-generated aerosols of known size and composition. Here, the performance of SpEx under realistic operating conditions in the field was assessed by comparison to extinction coefficients derived from commercial instruments that measured scattering and filter-based absorption coefficients at three discrete visible wavelengths. Good agreement was found between these two sets of extinction coefficients with slopes near unity for all three wavelengths within the SpEx measurement error (± 5 Mm−1). The meteorological conditions encountered during the cruise fostered diverse ambient aerosol populations with varying sizes and composition at concentrations spanning 2 orders of magnitude. The sampling inlet had a 50 % size cut of 1.3 µm diameter particles such that the in situ aerosol sampling suite deployed aboard ship measured fine-mode aerosols only. The extensive hyperspectral extinction data set acquired revealed that nearly all measured spectra exhibited curvature in logarithmic space, such that Ångström exponent (α) power law fits could lead to large errors compared to measured values. This problem was particularly acute for α values calculated over only visible wavelengths and then extrapolated to the UV, highlighting the need for measurements in this wavelength range. Second-order polynomial fits to the logarithmically transformed data provided a much better fit to the measured spectra than the linear fits of power laws. Building on previous studies that used total column aerosol optical depth observations to examine the information content of spectral curvature, the relationship between α and the second-order polynomial fit coefficients (a1 and a2) was found to depend on the wavelength range of the spectral measurement such that any given α maps into a line in (a1, a2) coefficient space with a slope of −2LN(λch), where λch is defined as the single wavelength that characterizes the wavelength range of the measured spectrum (i.e., the “characteristic wavelength”). Since the curvature coefficient values depend on λch, it must be taken into account when comparing values from spectra obtained from measurement techniques with different λch. Previously published work has shown that different bimodal size distributions of aerosols can exhibit the same α yet have differing spectral curvature with different (a1, a2). This implies that (a1, a2) contain more information about size distributions than α alone. Aerosol size distributions were not measured during KORUS-OC, and the data reported here were limited to the fine fraction, but the (a1, a2) maps obtained from the SpEx data set are consistent with the expectation that (a1, a2) may contain more information than α – a result that will be explored further with future SpEx and size distribution data sets.
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Wei, Rui, Herong Jin, and Yali Yi. "Research on the transmission error of swing-rod movable teeth transmission system." Mechanics & Industry 21, no. 4 (2020): 409. http://dx.doi.org/10.1051/meca/2020036.
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Using the two-tooth difference swing-rod movable teeth transmission system satisfying the drive function of large optical instruments as the study object, the influence of each component error on system transmission error is analysed. Each component error is presented by the vector method, and then it is transformed into equivalent error in the direction of the meshing action line based on the equivalent meshing error principle. The instantaneous transmission ratio of the system is obtained by the instantaneous velocity center method, and the system transmission error model is established. Using numerical analysis, the influence of each component error on the system transmission error is obtained. The transmission error test platform is used to test and analyze the transmission error of the two-tooth difference swing-rod movable teeth transmission system. The research results show that the swing-rod length error and the wave generator eccentric error have a great influence on the transmission error of the system among the six types of error factors, so they should be strictly controlled during design, processing and assembly. This study provides a theoretical basis for the rational allocation of machining errors and assembling errors of the two-tooth difference swing-rod movable teeth transmission system.
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Kusch, Wolfgang, Reinhold Zöllner, and Frank-Ulrich Dentler. "Georg von Neumayer: his influence on marine meteorology in the German Meteorological Service." Proceedings of the Royal Society of Victoria 123, no. 1 (2011): 27. http://dx.doi.org/10.1071/rs11027.
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Georg von Neumayer achieved outstanding scientific results and created the organisational framework for the successful completion of scientific tasks. Returning from Australia, Neumayer aimed to set up in Germany a state-owned centre for marine meteorology, hydrography, navigation, marine instruments and geomagnetism, with an emphasis on scientific research with practical application of the findings. Since 1868, a successfully operating private institute, Norddeutsche Seewarte, had existed in Hamburg. This institute provided instructions for sailing routes and the optimal use of favourable winds and currents. In 1875, the institute was transformed into an imperial institution, the ‘Deutsche Seewarte’ (German Marine Observatory), with a broad spectrum of marine responsibilities including meteorological forecasts and warnings, data acquisition and management, and climatology. Its first director was Georg von Neumayer, who led it to worldwide recognition. In 1903, he retired but the Deutsche Seewarte continued in his spirit. At the end of World War II, the institute was destroyed by bombs and ceased to exist. Today, the tasks are shared between Marine Meteorological Office of the Deutscher Wetterdienst specialising in the marine meteorological and related topics and the Federal Maritime and Hydrographic Agency.
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Liang, Fan, Xing Li Wu, Shi Gang Cui, and Li Zhao. "The Mixed Kalman and H Infinity Filter Based Robust Model Following Control Algorithm for CABG Beating Heart Surgery." Applied Mechanics and Materials 543-547 (March 2014): 1360–64. http://dx.doi.org/10.4028/www.scientific.net/amm.543-547.1360.
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In the CABG surgery the robot dynamically cancels the relative motion between the point of interest (POI) on the beating heart and robotic instruments, such that the surgeon can operate as if the heart is stationary. However, the highly nonlinear and non-stationary nature of the beating heart motion poses difficulties for robot to follow the characteristics of the beating heart motion. Furthermore, the surgery has potential safety risk if the robot system could not track the POI properly. Therefore, in order to minimize the effects caused by the uncertainty in the heart motion model during the surgery, a robust prediction based model following control algorithm is proposed here. The adaptive Autoregressive (AR) model integrated the mixed Kalman and H infinity filter to estimate the state of the beating heart motion in the sense of minimizing minimize both RMS motion estimation error and worst case motion estimation error. In addition, the linear quadratic optimal tracking theory was used to implement the model following controller. In such way a complicated heart motion tracking problem transformed to dynamic model following problem and the robust property of the tracking control is more effective. The method is verified by two prerecorded distinguished datasets on 3D test bed robotics.
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HEAMAWATANACHAI, SUMET, KITTIPONG CHAEMTHET, and TAWAT CHANGPAN. "DEVELOPMENT OF A MACHINE-VISION-BASED SYSTEM FOR RECORDING OF FORCE CALIBRATION DATA." International Journal of Modern Physics: Conference Series 24 (January 2013): 1360018. http://dx.doi.org/10.1142/s2010194513600185.
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This paper presents the development of a new system for recording of force calibration data using machine vision technology. Real time camera and computer system were used to capture images of the reading from the instruments during calibration. Then, the measurement images were transformed and translated to numerical data using optical character recognition (OCR) technique. These numerical data along with raw images were automatically saved to memories as the calibration database files. With this new system, the human error of recording would be eliminated. The verification experiments were done by using this system for recording the measurement results from an amplifier (DMP 40) with load cell (HBM-Z30-10kN). The NIMT's 100-kN deadweight force standard machine (DWM-100kN) was used to generate test forces. The experiments setup were done in 3 categories; 1) dynamics condition (record during load changing), 2) statics condition (record during fix load), and 3) full calibration experiments in accordance with ISO 376:2011. The captured images from dynamics condition experiment gave >94% without overlapping of number. The results from statics condition experiment were >98% images without overlapping. All measurement images without overlapping were translated to number by the developed program with 100% accuracy. The full calibration experiments also gave 100% accurate results. Moreover, in case of incorrect translation of any result, it is also possible to trace back to the raw calibration image to check and correct it. Therefore, this machine-vision-based system and program should be appropriate for recording of force calibration data.
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OLAGUNJU, Olasunkanmi Olusogo. "A Précis on Intellectual Property Rights: Challenges and Prospects for Nigeria's Economy." GATR Global Journal of Business Social Sciences Review 8, no. 3 (2020): 153–61. http://dx.doi.org/10.35609/gjbssr.2020.8.3(2).
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Objective - This research study examines the benefits and advantages associated with Intellectual Property Rights (IPRs) in Nigeria's ecosystem. It scrutinises the contributions of safety or security of heroic inventions and innovations to economic growth. Methodology/Technique – With the adoption of institutional theory, this study examines the pertinent legal instruments, administration and challenges of IPRs in Nigeria. The paper is specifically built on content analysis, key informant interviews, and expert insights which are used to unearth the institutional framework for transforming IPRs into sustainable economic or financial assets. Finding – Based on content validity of the research, it is concluded that IPRs can be transformed into sustainable economic wealth or tangible financial resources with the creation of institutional apparatus for mitigating theft, piracy, or illegal transfer of IPRs in Nigeria as well as other developing nations. Consequently, some key policy suggestions necessary to secure IPRs for economic growth or optimal performance are espoused in this study. Novelty - The paper makes findings relevant to how institutional weaknesses actually spearhead the growth of theft, piracy, and illegal exchange or utilisation of intellectual resources of Nigeria. Type of Paper: Review. JEL Classification: O31, O43, K21, O1, O17 Keywords: Institution; Rights; Economy; Property; Security; Administration. Reference to this paper should be made as follows: OLAGUNJU, O.O. 2020. A Precís on Intellectual Property Rights: Challenges and Prospects for Nigeria's Economy, Global J. Bus. Soc. Sci. Review 8(3): 153 – 161. https://doi.org/10.35609/gjbssr.2020.8.3(2)
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Yin, Liang, Ruonan Yang, and Yuliang Yao. "Channel Sounding and Scene Classification of Indoor 6G Millimeter Wave Channel Based on Machine Learning." Electronics 10, no. 7 (2021): 843. http://dx.doi.org/10.3390/electronics10070843.
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Millimeter wave, especially the high frequency millimeter wave near 100 GHz, is one of the key spectrum resources for the sixth generation (6G) mobile communication, which can be used for precise positioning, imaging and large capacity data transmission. Therefore, high frequency millimeter wave channel sounding is the first step to better understand 6G signal propagation. Because indoor wireless deployment is critical to 6G and different scenes classification can make future radio network optimization easy, we built a 6G indoor millimeter wave channel sounding system using just commercial instruments based on time-domain correlation method. Taking transmission and reception of a typical 93 GHz millimeter wave signal in the W-band as an example, four indoor millimeter wave communication scenes were modeled. Furthermore, we proposed a data-driven supervised machine learning method to extract fingerprint features from different scenes. Then we trained the scene classification model based on these features. Baseband data from receiver was transformed to channel Power Delay Profile (PDP), and then six fingerprint features were extracted for each scene. The decision tree, Support Vector Machine (SVM) and the optimal bagging channel scene classification algorithms were used to train machine learning model, with test accuracies of 94.3%, 86.4% and 96.5% respectively. The results show that the channel fingerprint classification model trained by machine learning method is effective. This method can be used in 6G channel sounding and scene classification to THz in the future.
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Li, Huimin, Shoudao Huang, Derong Luo, Jian Gao, and Peng Fan. "Dynamic DC-link Voltage Adjustment for Electric Vehicles Considering the Cross Saturation Effects." Energies 11, no. 8 (2018): 2046. http://dx.doi.org/10.3390/en11082046.
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The demands of remarkable reliability and high power density of traction systems are becoming more and more rigorous. The conflicting requirements imposed on the control strategy are higher accuracy and higher efficiency over the whole speed range. However, parameter variations caused by the cross coupling and magnetic saturation effect (omitted from the cross saturation effects in the following) are usually neglected in conventional control strategies, which could reduce the control precision. In order to fully consider the influence of parameter changes on the motor control and derive an approach that could realize the maximum efficiency during the whole speed range, this paper proposes a dynamic DC-link voltage adjustment strategy considering the cross coupling and magnetic saturation effects. The strategy can be categorized into three parts. Firstly, the torque request is transformed to the optimal current reference signal. Secondly, the differences between the setpoint and the real-time feedback signals of torque and voltage can be applied in the linearized function in the did,q coordinate. The solution guides the current vector into the optimal direction under the current and voltage limits to ensure the safety and reliability of the motor. Finally, last, the bus voltage can be modified according to the asked terminal voltage. A 10 kW prototype which instrumented a bidirectional DC-DC converter to regulating the bus voltage has been studied. The simulation and experiment results verify that the proposed control strategy can reduce the inverter losses in low speed region by offering the low bus voltage and track the actual maximum torque control trace more accurately, meanwhile, the flux weakening region can be delayed in high speed region by applying a high bus voltage. It helps the motor realize the high utilization rate of the DC-link voltage and guarantees the system reliability and robustness.
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Magnani, Lorenzo. "Thinking through drawing." Knowledge Engineering Review 28, no. 3 (2013): 303–26. http://dx.doi.org/10.1017/s026988891300026x.
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AbstractThe concept ofmanipulative abductionis devoted to capture the role of action in many interesting cognitive situations: action provides otherwise unavailable information that enables the agent to solve problems by starting and performing a suitable abductive process of generation or selection of hypotheses. We observe that many external things, usually inert from an epistemological point of view, can be transformed intoepistemic mediators. I will present some details derived from the history of the discovery of the non-Euclidean geometries that illustrate the relationships between strategies for anomaly resolution and visual thinking. Geometrical diagrams are external representations that play both amirrorrole (to externalize rough mental models) and anunveilingrole (as gateways to imaginary entities). I describe them as epistemic mediators able to perform various explanatory, non-explanatory, and instrumental abductive tasks (discovery of new properties or new propositions/hypotheses, provision of suitable sequences of models as able to convincingly verifying theorems, etc.). I am also convinced that they can be exploited and studied in everyday non-mathematical applications also to the aim of promoting new trends in artificial intelligence modeling of various aspects of hypothetical reasoning: finding routes, road signs, buildings maps, for example, in connection with various zooming effects of spatial reasoning. I also think that the cognitive activities of optical, mirror, and unveiling diagrams can be studied in other areas of manipulative and model-based reasoning, such as the ones involving creative, analogical, and spatial inferences, both in science and everyday situations so that this can extend the epistemological, computational, and the psychological theory.
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Subagiono, Yon, Harnedi Maizir, and Reni Suryanita. "Perilaku Mekanik Bata Ringan Dengan Penambahan Silica Fume." Jurnal Rekayasa Sipil (JRS-Unand) 16, no. 3 (2020): 194. http://dx.doi.org/10.25077/jrs.16.3.194-204.2020.
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Bata beton ringan memiliki keuntungan praktis dan ekonomis dalam pelaksanaan kontruksi sehingga permintaan pasar untuk bata ringan semakin meningkat selama beberapa tahun terakhir. Selain itu pemakaian bata beton konvensional sebagai bahan bagunan non-struktural dinilai masih cukup besar massa jenisnya sehingga memberikan beban lebih ke struktur bangunan. Untuk itu diperlukan bata beton yang memiliki bobot yang lebih ringan sehingga dapat meningkatkan efisiensi baik bahan dan beban yang ditahan struktur maupun pondasi dari bangunan. Penggunaan bata ringan pada umumnya sebagai non struktur berupa dinding panel dan pelat atap. Salah satu cara untuk mengurangi kepadatan bata beton ringan adalah dengan menambahkan pori-pori udara dalam campuran pasta semen atau mortar. Penambahan pori-pori udara dilakukan dengan penambahan foaming agent. Dalam perkembangan teknologi bahan bata ringan perlu ditingkatkan lagi efisiensi dari segi penggunaan bahan dan kualitas bata ringan itu sendiri. Penelitian ini bertujuan untuk menganalisis komposisi campuran yang optimal pada bata ringan tipe Cellular Lightweight Concrete dengan penambahan silica fume. Benda uji dibuat dalam ukuran 10 cm x 20 cm x 60 cm dengan memvariasikan komposisi silica fume dalam 5 komposisi yaitu 0%, 5%, 10% 15% dan 20% dari berat semen yang digunakan dalam campuran bahan. Selanjutnya dilakukan perawatan bata ringan pada umur 3 hari, 7 hari, 14 hari, 21 hari dan 28 hari. Pengujian mekanik yang dilakukan adalah pengujian kuat tekan secara merata pada bagian atas bata ringan. Instrumen pengukuran yang digunakan pada penelitian adalah load cell sebagai pengukur beban dan Linear Variable Differential Transformer (LVDT) untuk mengukur penurunan (displacement) yang terjadi pada permukaan yang dibebani. Data keluaran yang dapat diperoleh dari pengujian ini adalah kuat tekan, modulus elastisitas dan displacement. Nilai kuat tekan bata ringan pada umur 28 hari untuk komposisi 1 sebesar 0,47 MPa, komposisi 2 sebesar 0,82 MPa, komposisi 3 sebesar 0,87 MPa, komposisi 4 sebesar 0,70 MPa, dan komposisi 5 sebesar 0,61 MPa. Berdasarkan hasil penelitian dapat disimpulkan bahwa komposisi bahan campuran yang menggunakan bahan tambah silica fume dengan persentase 10% dari berat semen menghasilkan kuat tekan yang paling tinggi dengan penurunan permukaan sebesar 3.5 mm saat dibebani dan modulus elastisitas 527.62 kg/m3. Diharapkan hasil penelitian ini dapat dijadikan bahan referensi dalam industri dan penelitian bata ringan dengan bahan tambah silica fume untuk mendapatkan sifat mekanik yang optimal pada bata ringan.
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García Pazmiño, Mercedes Angélica, Francisco García Ucha, Nataly Alejandra Arévalo García, and Sylvia Teresa García Pazmmiño. "Presiones Deportivas y Disposición Óptima Combativa (Sports Pressures and Optimal Combative Disposition)." Retos, no. 35 (November 23, 2018): 335–40. http://dx.doi.org/10.47197/retos.v0i35.61911.
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La competición es el campo de prueba del deportista, donde experimentan Presiones Precompetitivas (PP), que influyen en la esfera psíquica, conductual y actitudinal del atleta. Los deportistas independiente de la edad, especialidad, experiencia deportiva, vivencian y afrontan las PP de diferente manera. El objetivo del estudio fue relacionar PP con la Disposición Óptima Combativa (DOC) y el Rendimiento Deportivo (RD), en deportistas que practican natación, triatlón, ciclismo y atletismo. El abordaje metodológico de tipo cuantitativo con diseño transversal; considerando las etapas del macrociclo de entrenamiento, se aplicó los instrumentos: Coeficiente de Valoración (CV); Perfiles del Estado de Ánimo (POMS); índice de rendimiento deportivo (IRP); síntoma de la carga psíquica de Frester (SCP); entrevista de rendimiento deportivo (RD). Se aplicó el método científico e hipotético deductivo; la técnica de entrevista y observación directa de manifestaciones fenoménicas visibles durante los entrenamientos y competencias. La hipótesis probó una correlación negativa media (r=-65); aceptando el vínculo entre las variables; es decir, a mayor presión psicológica, menor disposición óptima combativa; Los resultados demostraron que las PP externas e internas, están asociadas significativamente con en el RD, en dependencia del CV; si éste es positivo, mejorará el RD, es el caso de los atletas y ciclistas, quienes convierten las PP en retos, generando actitudes y expectativas que estimulan a una DOC y mejor RD acorde a las posibilidades y proyecciones. Finalmente, el estudio subrayó la necesidad del entrenamiento psicológico, para el desarrollo de las habilidades y destrezas psíquicas. Abstract. Competition is athletes' test field, where they experience precompetitive pressures (PP). Those experiences influence athletes’ psychic, behavioral, and attitudinal spheres. Regardless of age, specialty, or performance, sportsmen are frequently exposed to PP in different ways. The objective of this research was to relate PP with optimal combative disposition (DOC), and sports performance (RD) in athletes who practice swimming, triathlon, cycling, and running. The study utilizes a quantitative approach with a transversal design, taking into account the stages of training macrocycle. The instruments administered were: valuation coefficient (CV), Profiles of the State of Mind (POMS), sports performance Index (IRP), symptom of Frester's psychic burden (SCP), and sports performance interview (RD). The scientific and hypothetical deductive method was applied; techniques of interviewing and direct phenomena observation were performed during training and competitions. The hypothesis tested a mean negative correlation (r = -65) accepting the correlation between variables; that is, to greater psychological pressure, less optimal combative disposition. The results showed that both external and internal PP are significantly associated with RD. Moreover, external and internal PP are dependent on CV; if CV is positive, RD will improve, as the case of athletes and cyclists. They have transformed their PP into challenges, generating attitudes and expectations that stimulate DOC and better RD according to the possibilities or projections. Finally, the study emphasized the need for psychological training, for the development of psychic abilities and skills.
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Stepnov, Andrey, Vladimir Chernykh, and Alexey Konovalov. "The Seismo-Performer: A Novel Machine Learning Approach for General and Efficient Seismic Phase Recognition from Local Earthquakes in Real Time." Sensors 21, no. 18 (2021): 6290. http://dx.doi.org/10.3390/s21186290.
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When recording seismic ground motion in multiple sites using independent recording stations one needs to recognize the presence of the same parts of seismic waves arriving at these stations. This problem is known in seismology as seismic phase picking. It is challenging to automate the accurate picking of seismic phases to the level of human capabilities. By solving this problem, it would be possible to automate routine processing in real time on any local network. A new machine learning approach was developed to classify seismic phases from local earthquakes. The resulting model is based on spectrograms and utilizes the transformer architecture with a self-attention mechanism and without any convolution blocks. The model is general for various local networks and has only 57 k learning parameters. To assess the generalization property, two new datasets were developed, containing local earthquake data collected from two different regions using a wide variety of seismic instruments. The data were not involved in the training process for any model to estimate the generalization property. The new model exhibits the best classification and computation performance results on its pre-trained weights compared with baseline models from related work. The model code is available online and is ready for day-to-day real-time processing on conventional seismic equipment without graphics processing units.
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Zhang, Pei, Ying Li, Dong Wang, and Jiyue Wang. "RS-SSKD: Self-Supervision Equipped with Knowledge Distillation for Few-Shot Remote Sensing Scene Classification." Sensors 21, no. 5 (2021): 1566. http://dx.doi.org/10.3390/s21051566.
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While growing instruments generate more and more airborne or satellite images, the bottleneck in remote sensing (RS) scene classification has shifted from data limits toward a lack of ground truth samples. There are still many challenges when we are facing unknown environments, especially those with insufficient training data. Few-shot classification offers a different picture under the umbrella of meta-learning: digging rich knowledge from a few data are possible. In this work, we propose a method named RS-SSKD for few-shot RS scene classification from a perspective of generating powerful representation for the downstream meta-learner. Firstly, we propose a novel two-branch network that takes three pairs of original-transformed images as inputs and incorporates Class Activation Maps (CAMs) to drive the network mining, the most relevant category-specific region. This strategy ensures that the network generates discriminative embeddings. Secondly, we set a round of self-knowledge distillation to prevent overfitting and boost the performance. Our experiments show that the proposed method surpasses current state-of-the-art approaches on two challenging RS scene datasets: NWPU-RESISC45 and RSD46-WHU. Finally, we conduct various ablation experiments to investigate the effect of each component of the proposed method and analyze the training time of state-of-the-art methods and ours.
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Li, Xue-Ying, Yan Liu, Mei-Rong Lv, Yan Zou, and Ping-Ping Fan. "Calibration Transfer of Soil Total Carbon and Total Nitrogen between Two Different Types of Soils Based on Visible-Near-Infrared Reflectance Spectroscopy." Journal of Spectroscopy 2018 (September 25, 2018): 1–10. http://dx.doi.org/10.1155/2018/8513215.
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Although visible-near-infrared spectroscopy can rapidly and accurately determine soil nutrients without sample destruction, some problems remain unresolved, such as the mismatch of the established spectral model with different types of samples, limiting the wide application of this technology. Here, we took riverside and mountain soils as examples to explore the calibration transfer between two different types of soils by the WMPDS-S/B algorithm (wavelet multiscale piecewise direct standardization combined with Slope/Bias correction method) and by adding new samples. The predicted TN and TC concentrations improved significantly after being transformed. Compared with adding new samples, the WMPDS-S/B algorithm obtained more accurate results. The average relative errors dropped from 440.2% (without transformation) to approximately 6% for TN and from 342.0% to approximately 7% for TC. The maximum relative errors were reduced from 538.1% to less than 20% for TN and from 403.7% to less than 20% for TC. The RMSEP decreased from 2.42 to approximately 0.04 for TN and from 15.74 to approximately 0.4 for TC. The WMPDS-S/B algorithm had advantages in selecting fewer known samples and obtaining better prediction results. In contrast to past studies, which resolved the calibration transfer between different spectrometers and the measurement environment for the same samples, our study resolved the calibration transfer between different types of samples under the same spectrometer and the measurement environment. The former could only be used for correction among instruments, while the latter fundamentally solved the problem of model sharing across different samples.
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Yao, Yang, Sungtae Shin, Azin Mousavi, et al. "Unobtrusive Estimation of Cardiovascular Parameters with Limb Ballistocardiography." Sensors 19, no. 13 (2019): 2922. http://dx.doi.org/10.3390/s19132922.
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This study investigates the potential of the limb ballistocardiogram (BCG) for unobtrusive estimation of cardiovascular (CV) parameters. In conjunction with the reference CV parameters (including diastolic, pulse, and systolic pressures, stroke volume, cardiac output, and total peripheral resistance), an upper-limb BCG based on an accelerometer embedded in a wearable armband and a lower-limb BCG based on a strain gauge embedded in a weighing scale were instrumented simultaneously with a finger photoplethysmogram (PPG). To standardize the analysis, the more convenient yet unconventional armband BCG was transformed into the more conventional weighing scale BCG (called the synthetic weighing scale BCG) using a signal processing procedure. The characteristic features were extracted from these BCG and PPG waveforms in the form of wave-to-wave time intervals, wave amplitudes, and wave-to-wave amplitudes. Then, the relationship between the characteristic features associated with (i) the weighing scale BCG-PPG pair and (ii) the synthetic weighing scale BCG-PPG pair versus the CV parameters, was analyzed using the multivariate linear regression analysis. The results indicated that each of the CV parameters of interest may be accurately estimated by a combination of as few as two characteristic features in the upper-limb or lower-limb BCG, and also that the characteristic features recruited for the CV parameters were to a large extent relevant according to the physiological mechanism underlying the BCG.
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Burger, Zoe C., Si Thu Aung, Hlaing Thazin Aung, Timothy Rodwell, and Marva Seifert. "658. Effect of HIV Status on Tuberculosis Load as Detected by Xpert MTB/RIF in Sputum vs. Saliva Samples." Open Forum Infectious Diseases 7, Supplement_1 (2020): S385—S386. http://dx.doi.org/10.1093/ofid/ofaa439.851.
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Abstract Background Tuberculosis (TB) is the most common co-infection among people living with HIV, but HIV positivity is associated with a lower Mycobacterium tuberculosis (MTB) bacillary load in sputum, making TB often difficult to diagnose with current diagnostic solutions. GeneXpert MTB/RIF (Cepheid, USA), a rapid, molecular diagnostic assay, has transformed the TB diagnostic landscape and can be used to diagnose TB and limited drug resistance in HIV patients from direct clinical samples in &lt; 2 hours, but results can be significantly affected by sample bacterial load, which is quantified by the GeneXpert MTB/RIF (Xpert) instrument using Ct values. Our primary objective was to assess how a patient’s HIV status affected their MTB bacterial load in sputum vs. saliva samples submitted for Xpert diagnosis of TB. Methods We completed a retrospective analysis of &gt;4,000 patient records from the Myanmar National TB Program captured as part of a nation-wide electronic reporting system developed with the assistance of FIND (Geneva). De-identified records included HIV status, Xpert testing results, and for a subset of patients, specimen type. With this diagnostic information, we compared the distribution of MTB load (quantified by Xpert Ct values) in sputum and saliva in HIV positive vs. HIV negative patients using STATA. Results Based on mean Ct value comparison independent of HIV status, saliva samples (mean Ct = 22.7) contained a significantly lower bacterial load of MTB as compared to sputum samples (mean Ct=19.2, p &lt; .001).Within saliva samples, a lower bacterial load was also detected in HIV positive patients (mean Ct = 26.9) compared to HIV negative patients (mean Ct = 22.3, p&lt; .05). Similarly, in sputum samples, a lower bacterial load was detected in HIV positive patients (mean Ct = 21.6) compared to HIV negative patients (mean Ct = 19.0, p &lt; .001) (Figure 1). Figure 1. Ct Values by HIV Status and Specimen Type Conclusion Sputum samples have a significantly higher bacterial load on average compared to saliva samples independent of HIV status. Additionally, when looking at both saliva and sputum as sample types, HIV positive patients have significantly lower bacterial load than individuals who are HIV negative. Based on these results, sputum is the optimal sample type for Xpert TB detection, especially in people living with HIV. Disclosures All Authors: No reported disclosures
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Antuña-Marrero, Juan-Carlos, Graham W. Mann, Philippe Keckhut, Sergey Avdyushin, Bruno Nardi, and Larry W. Thomason. "Shipborne lidar measurements showing the progression of the tropical reservoir of volcanic aerosol after the June 1991 Pinatubo eruption." Earth System Science Data 12, no. 4 (2020): 2843–51. http://dx.doi.org/10.5194/essd-12-2843-2020.
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Abstract. A key limitation of volcanic forcing datasets for the Pinatubo period is the large uncertainty that remains with respect to the extent of the optical depth of the Pinatubo aerosol cloud in the first year after the eruption, the saturation of the SAGE-II instrument restricting it to only be able to measure the upper part of the aerosol cloud in the tropics. Here we report the recovery of stratospheric aerosol measurements from two shipborne lidars, both of which measured the tropical reservoir of volcanic aerosol produced by the June 1991 Mount Pinatubo eruption. The lidars were on board two Soviet vessels, each ship crossing the Atlantic, their measurement datasets providing unique observational transects of the Pinatubo cloud across the tropics from Europe to the Caribbean (∼ 40 to 8∘ N) from July to September 1991 (the Professor Zubov ship) and from Europe to south of the Equator (∼ 40∘ N to 8∘ S) between January and February 1992 (the Professor Vize ship). Our philosophy with the data recovery is to follow the same algorithms and parameters that appear in the two peer-reviewed articles that presented these datasets in the same issue of GRL in 1993, and here we provide all 48 lidar soundings made from the Professor Zubov and 11 of the 20 conducted from the Professor Vize, ensuring we have reproduced the aerosol backscatter and extinction values in the figures of those two papers. These original approaches used thermodynamic properties from the CIRA-86 standard atmosphere to derive the molecular backscattering, vertically and temporally constant values applied for the aerosol backscatter-to-extinction ratio, and the correction factor of the aerosol backscatter wavelength dependence. We demonstrate this initial validation of the recovered stratospheric aerosol extinction profiles, providing full details of each dataset in this paper's Supplement S1, the original profiles of backscatter ratio, and the calculated profiles of aerosol backscatter and extinction. We anticipate these datasets will provide potentially important new observational case studies for modelling analyses, including a 1-week series of consecutive soundings (in September 1991) at the same location showing the progression of the entrainment of part of the Pinatubo plume into the upper troposphere and the formation of an associated cirrus cloud. The Zubov lidar dataset illustrates how the tropically confined Pinatubo aerosol cloud transformed from a highly heterogeneous vertical structure in August 1991, maximum aerosol extinction values around 19 km for the lower layer and 23–24 for the upper layer, to a more homogeneous and deeper reservoir of volcanic aerosol in September 1991. We encourage modelling groups to consider new analyses of the Pinatubo cloud, comparing the recovered datasets, with the potential to increase our understanding of the evolution of the Pinatubo aerosol cloud and its effects. Data described in this work are available at https://doi.org/10.1594/PANGAEA.912770 (Antuña-Marrero et al., 2020).