HPM meters are required for the assessment of fields generated by sources of high-power microwaves. Finding the inverse calibration curves for such instruments is important for ensuring accuracy. The procedure is relatively simple for meters consisting of linear devices but there can also be hardware solutions implementing nonlinear ones. The objective of the present work was to develop a convenient procedure to allow finding such a curve when the meter uses a D-dot probe and a power detector. For that purpose, the results of low voltage measurements describing the properties of the detector were first analysed. Then a software code was developed to estimate the RMS value of an incident field based on measured output and frequency response. The response was estimated with very low electric field. And finally, the performance of the proposed procedure was verified by tests conducted with high electric field in a TEM cell. High conformity of the output of the meter with fields of known values was demonstrated. The maximum error related to the meter range did not exceed 4%.
The objective of the study was to assess the potential use of optical measuring instruments to determine the minimum chip thickness in face milling. Images of scanned surfaces were analyzed using mother wavelets. Filtration of optical signals helped identify the characteristic zones observed on the workpiece surface at the beginning of the cutting process. The measurement data were analyzed statistically. The results were then used to estimate how accurate each measuring system was to determine the minimum uncut chip thickness. Also, experimental verification was carried out for each mother wavelet to assess their suitability for analyzing surface images.
We present spectral emission characteristics from laser-plasma EUV/SXR sources produced by irradiation of < 1 J energy laser pulse on eleven different double stream gas puff targets, with most intense electronic transitions identified in the spectral range from 1 nm to 70 nm wavelength which corresponds to photon energy from 18 eV to 1240 eV. The spectra were obtained using grazing incidence and transmission spectro- graphs from laser-produced plasma emission, formed by the interaction of a laser beam with a double stream gas puff target. Laser pulses with a duration of 4 ns and energy of 650 mJ were used for the experiment. We present the results obtained from three different spectrometers in the wavelength ranges of SXR (1–5.5 nm), SXR/EUV (4–15.5 nm), and EUV (10–70 nm). In this paper, detailed information about the source, gas targets under investigation, the experimental setup, spectral measurements and the results are presented and discussed. Such data may be useful for the identification of adequate spectral emissions from gasses in the EUV and SXR wavelength ranges dedicated to various experiments (i.e. broadband emission for the X-ray coherence tomography XCT) or may be used for verification of magnetohydrodynamic plasma codes.
The article presents methodology for testing the electric strength of vacuum chambers designed for modern medium voltage switchgear developed by the authors, using two innovative test stands designed and constructed by the research team above. Verification of the correctness of operation of the test stands, as well as the validity of the developed methodology was carried out by performing a series of tests. It was determined that below certain pressure values in the tested chamber (from about 5.0×10 0 Pa for station 1 and for about 4.0×10 -1 Pa for station 2), the electric strength maintains a constant value, which guarantees stable operation of the vacuum chamber. The values of the total measurement uncertainty for the electric strength tests were also estimated.
The Lithuanian national standard of electric resistance is maintained as the basis for calibration and measurement capabilities published in the key comparison database of the International Bureau of Weights and Measures (BIPM). The stability and uncertainty of the resistance value measurements, performed since 2004 using the calibrated values of the standard resistors to predict their future behaviour as well as influence of environmental conditions, are discussed. Also discussed is the recovery of a standard resistor which had undergone a mechanical disturbance. It is concluded that the standard resistors operated by the Lithuanian National Electrical Standards Laboratory feature stable drift of resistance, which is well predicted by means of linear regression.
Virtual reality (VR) has become a realistic alternative to conventional learning methods in numerous fields including military training. Accurate and precise tracking of a user wearing a head-mounted display is necessary to achieve an immersive VR experience. The widely available SteamVR system, where licensed users can design and construct trackers optimized for a given application can be an alternative to very expensive professional motion tracking. This paper presents the complete design process of a SteamVR tracker dedicated to a shooting simulation in a VR environment.We describe the optimization and simulation of the tracker’s shape and configuration of the sensors. In the simulation phase the developed model had better parameters than its commercial counterparts. Next, the optimized prototype was constructed and configured. The dedicated and automated measuring arrangement provided experimental verification of the tracker’s performance. Tracking performance as well as the accuracy and precision of both position and orientation measurements were determined and compared with simulations, which proved that the simulation software can accurately predict selected properties of the proposed tracker.
Electrified railways are an example of AC single phase distribution networks. A non-negligible amount of active and nonactive power may be related to harmonics, especially for distorted highly-loaded systems. The paper considers the relevance of the harmonic power terms in order to identify distortion sources in a single-point perspective, in line with the approach of EN 50463 for the quantification of the power and energy consumption. Some single-point Harmonic Producer Indicators (HPI) based on harmonic active power direction and nonactive distortion power terms are reviewed and evaluated using pantograph voltage and current measured during several hours of runs in two European AC railways (operated at 16.7 and 50 Hz). The HPI based on active power shows to be consistent and provides detailed information of rolling stock characteristic components under variable operating conditions; those based on nonactive distortion power are global indexes and hardly can operate with complex harmonic patterns in variable operating conditions.
The paper presents a detailed theoretical background for coordinate measurement uncertainty evaluation by means of Type B evaluation method, taking into account information on accuracy of a coordinate measuring system given with the formula for maximum permissible errors of length measurement and verification test results. A proposal for evaluation of the verification test results is made. A measurement model based on the point-plane distance equation is presented. A detailed analysis of the partial derivatives (sensitivity factors in an uncertainty budget) of the measurement model is presented. The analyses of measurement uncertainty for different geometrical characteristicswere conducted using this measurement model. Examples of uncertainty evaluation for geometrical deviations are presented: position of a point related to a datum plane and flatness in the case of convex or concave surfaces. The examples include detailed uncertainty budgets.
The paper examines the usage of Convolutional Bidirectional Recurrent Neural Network (CBRNN) for a problem of quality measurement in a music content. The key contribution in this approach, compared to the existing research, is that the examined model is evaluated in terms of detecting acoustic anomalies without the requirement to provide a reference (clean) signal. Since real music content may include some modes of instrumental sounds, speech and singing voice or different audio effects, it is more complex to analyze than clean speech or artificial signals, especially without a comparison to the known reference content. The presented results might be treated as a proof of concept, since some specific types of artefacts are covered in this paper (examples of quantization defect, missing sound, distortion of gain characteristics, extra noise sound). However, the described model can be easily expanded to detect other impairments or used as a pre-trained model for other transfer learning processes. To examine the model efficiency several experiments have been performed and reported in the paper. The raw audio samples were transformed into Mel-scaled spectrograms and transferred as input to the model, first independently, then along with additional features (Zero Crossing Rate, Spectral Contrast). According to the obtained results, there is a significant increase in overall accuracy (by 10.1%), if Spectral Contrast information is provided together with Mel-scaled spectrograms. The paper examines also the influence of recursive layers on effectiveness of the artefact classification task.
This article concerns a new method of assessing the thread cutting process and the quality of the formed thread using the method of optical observation of the workpiece during machining. A series of digital images of the thread profile was taken in transmitted light for each tool infeed. Such images, obtained with high resolution for three angular positions, were binarized, with the space between ridges taken in successive infeeds identified as “void”, and its projection was then parameterized. Two of these parameters, area of void and aspect ratio, were used as indicators of the technological quality of the thread. The suitability of the selected parameters for technological description of the thread was verified using the example of titanium alloy thread turning under ambient and cryogenic conditions.
In automatic and accurate reading recognition of analog meters based on machine vision, one of important issues is the detection of pointer features, which includes the meter center and pointer image processing. The current automatic-recognition approaches to reading analog meters often consist in locating the meter center based on the dial region or its border. The located center is not coincident with the rotation center of pointer which leads to inevitable reading errors. In the paper, the centripetalism of annular scale lines is used to calculate the position of the pointer rotation center. First, it uses the region growing method to locate the dial region and uses the eccentricity measure to extract annular scale lines. Second, the parameters of these scale lines are estimated with the Hough transform method. Then, the common intersection of a group of lines, i.e., the meter rotation center, is determined with the maximum probability criterion. Finally, the pointer centerline and direction are detected through the calculated center and the Hough transform results. The simulated and experimental results demonstrate that the proposed method can accurately locate the pointer rotation center and obtain pointer centerline. Moreover, it is applicable to the meter image captured under a slant camera view or with uneven light illumination.
The paper presents a circuit structure that can be used for powering an IoT (Internet of Things) sensor node and that can use energy just from its surroundings. The main advantage of the presented solution is its very low cost that allows mass applicability e.g. in the IoT smart grids and ubiquitous sensors. It is intended for energy sources that can provide enough voltage but that can provide only low currents such as piezoelectric transducers or small photovoltaic panels (PV) under indoor light conditions. The circuit is able to accumulate energy in a capacitor until a certain level and then to pass it to the load. The presented circuit exhibits similar functionality to a commercially available EH300 energy harvester (EH). The paper compares electrical properties of the presented circuit and the EH300 device, their form factors and costs. The EH circuit’s performance is tested together with an LTC3531 buck-boost DC/DC converter which can provide constant voltage for the following electronics. The paper provides guidelines for selecting an optimal capacity of the storage capacitor. The functionality of the solution presented is demonstrated in a sensor node that periodically transmits measured data to the base station using just the power from the PV panel or the piezoelectric generator. The presented harvester and powering circuit are compact part of the sensor node’s electronics but they can be also realized as an external powering module to be added to existing solutions.
Up to the present day Suhrawardy remains a controversial figure in both parts of Bengal, with Hindus often seeing him as their fierce persecutor and Bangladeshi Muslims hailing him as their country’s forefather and preacher of communal unity. This article analyses his actions during the period of his Prime Ministership (1946–1947) looking for the sources of the above dichotomy. It argues that although Suhrawardy displayed a mild communal bias at times, circumstances made him inconsistent, being as he was trapped between right wing of Muslim League, the Hindu masses unwilling to trust him and (until the end of 1946) Congress ambitions to inherit the whole Raj. The need to act quickly due to Viceroy Mountbatten’s haste, as well as the PM’s lack of social skills were other factors contributing to failure of his last initiative – United Bengal Scheme – despite his genuine efforts towards Hindu-Muslim settlement and agrarian reforms.
The main concern of the present paper is to determine which types of linguistic descriptions are fit to properly express a complex reality such as developed in Jaina theory of universals and particulars presented in the Jaina Literature of the Classical Period (5th–10th c. CE) in order to demonstrate a way in which the Jaina theory of universals and particulars has an impact upon the way we describe reality through language. I take into consideration the fact that, according to the Jaina philosophy, reality is not describable in the complete way and that there is always – in any linguistic act of picturing the world – the margin of non-cognizance and non-expressiveness. The Jaina philosophy of language offers the original solutions, different from those given by other Indian thinkers, to the abovementioned problems.
The article examines two Aramaic contracts found on the island Elephantine and dating from the early fifth century B.C. The first one is a loan contract providing for payment of compound interest on silver lent: interest not paid timely is to be added to the capital and itself becomes interest-bearing at the same rate until actual repayment. If this is not done at an agreed date, the remaining debt is doubled. The second contract concerns delivery of barley and lentils from a ship to a royal store-house deserving a garrison. The parties are the ship-officer and functionaries acting on behalf of the store-house, where barley and lentils are supposed to be brought. It is a contract of delivery combining its acceptation on the ship and the foreseen completion of the contract in the store-house with expected financial results. Both contracts refer to silver “by the stone-weights of Ptah” and record its alloy.
Jonas Hassen Khemiri, born in 1978, is one of the most interesting contemporary Swedish and European writers with a Tunisian immigrant background. His second novel Montecore: en unik tiger ( Montecore: The Silence of the Tiger), published in 2006, has got an epistolary form deducted from the exchange of letters between Kadir and Jonas. However, the main character of the novel is Abbas Khemiri – the disappearing, estranged father of Jonas – a figure close to the real writer. Khemiri’s book has got an innovative linguistic form and contains many erudite references to the phenomena of popular culture. It is also a complex portrayal of the different generations of (mainly Arab-based) immigrant and post-immigrant communities in Sweden coupled with a nuanced look on bright and dark sides of the Swedish state, model of identity and integration. This material is enriched by the examples taken from Khemiri’s novel Everything I Don’t Remember and short story As You Would Have Told It To Me (Sort Of) If We Had Known Each Other Before You Died.
This article discusses an unknown tradition from the Malay Archipelago, namely the island of Lombok. The article describes a spirit possession ceremony, as it was practised in East Lombok before being subject to a ban in 1984. It also explains the reasons for prohibition and explores a recent revival of the tradition. The discussion draws a parallel with similar traditions from late colonial Malaysia. Aside from similar functions as healing rites, the traditions many times use the same ceremonial equipment during the ceremonies and have identical symbols. This encourages us to look for connections between the Sasaks in Lombok and the Malays in Malaysia and Sumatra. The article suggests some direct connections between the two, but also takes indirect connections into consideration, for example, the rule of the Bugis-Makassarese people, who played an important role in both of these corners of the archipelago.
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