Investigation on Online DGA Monitoring to Determine Transformer Health Index Using Machine Learning

The Dissolve Gas Analysis (DGA) to determine the ageing and degradation of the transformer is standard and routine periodic maintenance. In general, there are two DGA analysis methods which are conventional (lab-based) and online monitoring. DGA monitoring will be able to access to detect incipient fault and transformer failure. Several techniques are available to analyse, interpret and diagnose the DGA result, such as IEEE standard, IEC 60599 standard, Key Gas Method, and Duval methods. There are several Machine Learning (ML) techniques has been explored such as Support Vector Machine (SVM), Artificial Neural Network (ANN), K-Neural Neighbours (KNN), Random Neural Network (RNN), and Fuzzy Logic for determining the transformer condition, including fault diagnostic and fault detection. However, there are unexplored studies to combine the commercial device to determine the Health Index (HI) of Transformer. In this study, an ML method with the available input feature from the commercial device to the network is trained to determine the HI. In general, the benchmark dataset from the existing work is employed to validate the proposed investigation. There are 730 datasets comprising five different classes; 1) Very Good, 2) Good, 3) Fair, 4) Poor, 5) Very Poor in determining the HI of a transformer. Conventional rule to partition the train and testing dataset with a 70:30 ratio is employed in this study. The maximum accuracy results and method for 1) M1 is 66.67% for ANN, 2) M2 is 68.49% for ANN, 3) M3 is 76.71% for KNN, 4) M5 is 76.26% for ANN, 5) M6 is 79.00% for ANN and 6) M7 is 86.30% for ANN. In conclusion, the multi-gas device will have a good accuracy performance and provide a good HI indicator to classify the condition of the transformer, which can be used for preventive maintenance.

The Lightfield Microscope Eyepiece

Lightfield microscopy has raised growing interest in the last few years. Its ability to get three-dimensional information about the sample in a single shot makes it suitable for many applications in which time resolution is fundamental. In this paper we present a novel device, which is capable of converting any conventional microscope into a lightfield microscope. Based on the Fourier integral microscope concept, we designed the lightfield microscope eyepiece. This is coupled to the eyepiece port, to let the user exploit all the host microscope’s components (objective turret, illumination systems, translation stage, etc.) and get a 3D reconstruction of the sample. After the optical design, a proof-of-concept device was built with off-the-shelf optomechanical components. Here, its optical performances are demonstrated, which show good matching with the theoretical ones. Then, the pictures of different samples taken with the lightfield eyepiece are shown, along with the corresponding reconstructions. We demonstrated the functioning of the lightfield eyepiece and lay the foundation for the development of a commercial device that works with any microscope.

Calibration of a Digital Current Transformer Measuring Bridge: Metrological Challenges and Uncertainty Contributions

In this paper, we consider the calibration of measuring bridges for non-conventional instrument transformers with digital output. In this context, the main challenge is represented by the necessity of synchronization between analog and digital outputs. To this end, we propose a measurement setup that allows for monitoring and quantifying the main quantities of interest. A possible laboratory implementation is presented and the main sources of uncertainty are discussed. From a metrological point of view, technical specifications and statistical analysis are employed to draw up a rigorous uncertainty budget of the calibration setup. An experimental validation is also provided through the thorough characterization of the measurement accuracy of a commercial device in use at METAS laboratories. The proposed analysis proves how the calibration of measuring bridges for non-conventional instrument transformers requires ad hoc measurement setups and identifies possible space for improvement, particularly in terms of outputs’ synchronization and flexibility of the generation process.

Multimodal and Multiview Wound Monitoring with Mobile Devices

Along with geometric and color indicators, thermography is another valuable source of information for wound monitoring. The interaction of geometry with thermography can provide predictive indicators of wound evolution; however, existing processes are focused on the use of high-cost devices with a static configuration, which restricts the scanning of large surfaces. In this study, we propose the use of commercial devices, such as mobile devices and portable thermography, to integrate information from different wavelengths onto the surface of a 3D model. A handheld acquisition is proposed in which color images are used to create a 3D model by using Structure from Motion (SfM), and thermography is incorporated into the 3D surface through a pose estimation refinement based on optimizing the temperature correlation between multiple views. Thermal and color 3D models were successfully created for six patients with multiple views from a low-cost commercial device. The results show the successful application of the proposed methodology where thermal mapping on 3D models is not limited in the scanning area and can provide consistent information between multiple thermal camera views. Further work will focus on studying the quantitative metrics obtained by the multi-view 3D models created with the proposed methodology.

Fiber Optic Sensors Based on the Faraday Effect

Some 175 years ago Michael Faraday discovered magnetic circular birefringence, now commonly known as the Faraday effect. Sensing the magnetic field through the influence that the field has on light within the fiber optic sensor offers several advantages, one of them fundamental. These advantages find application in the measurement of electric current at high voltages by measuring the induced magnetic field, thus warranting application for this kind of fiber optic sensor (FOS) in future smart grids. Difficulties in designing and manufacturing high-performance FOSs were greatly alleviated by developments in optical telecommunication technology, thus giving new impetus to magnetometry based on the Faraday effect. Some of the major problems in the processing of optical signals and temperature dependence have been resolved, yet much effort is still needed to implement all solutions into a single commercial device. Artificial structures with giant Faraday rotation, reported in the literature in the 21st century, will further improve the performance of FOSs based on the Faraday effect. This paper will consider obstacles and limits imposed by the available technology and review solutions proposed so far for fiber optic sensors based on the Faraday effect.

1431 Stoma Intubation, Isolation and Negative Pressure Wound Therapy for Complex Stoma-Associated Wounds: New Technique and Case Series

Background The use of negative pressure wound therapy (NPWT) in colorectal surgery has been demonstrated for treating perineal defects, enterocutaneous fistula and stoma dehiscence. Here we describe a technique for closure of complex stoma-associated wounds using a novel commercial intubation device alongside NPWT to protect the surrounding wound from the stoma effluent. The device has previously described for use with enterocutaneous fistula. We present two cases that have been successfully treated with this technique. Technique and Cases The first case is of 88-year-old women with a retracted loop ileostomy and the second a 48 year-old male with a retracted end colostomy. Both patients underwent significant emergency peristomal debridement and in both cases the commercial device was deployed to intubate the stoma. VAC foam and standard adhesive dressings were used to form a quality seal and the pressure set to 125mmHg. In both cases near complete healing was achieved to the point that standard stoma bags and management could be used. Conclusions This is the first description of the use of an isolation device in complex stoma associated wounds. We have found the Fistula Funnel to be highly effective in this context.

Effect of Ge Mole Fraction on Performance of Underlapped Gate-All-Around SiGe-Source Tunneling Field-Effect Transistors

In this paper, we propose the design optimization of underlapped Si1–xGex-source tunneling field-effect transistors (TFETs) with a gate-all-around structure. The band-to-band tunneling rates, tunneling barrier widths, I–V transfer characteristics, threshold voltages, on/off current ratios, and subthreshold swings (SSs) were analyzed by varying the Ge mole fraction of the Si1–xGex source using a commercial device simulator. In particular, a Si0.2Ge0.8-source TFET among our proposed TFETs exhibits an on/off current ratio of approximately 1013, and SS of 27.4 mV/dec.

In Vitro Evaluation of the Stabilization Time of Chemical Bonds During Setting Reaction and Microhardness of Preheated Glass-Ionomer Cements

SUMMARY Objectives: To evaluate the effect of preheating glass-ionomer cement (GIC) restorative materials on stabilization time (ST) of their metal carboxylate bonds and on microhardness. Methods and Materials: Two conventional highviscosity GICs, Ketac Universal (3M ESPE) and Equia Forte (GC), were evaluated. The thermographic camera was used to measure the temperature inside the glass-ionomer cement capsules before and after heating. The preheating of capsules was performed at 54°C for 30 seconds in a commercial device. Characterization of ST in the GICs was determined by Fourier Transform Infrared (FTIR) spectroscopy. For this, 10 samples of each material were prepared, five in the non-preheated group (control) and five with preheating. FTIR spectra were obtained 10 minutes after mixing (control group) or after heating and then every 10 minutes for 120 minutes. For the microhardness test, 20 cylindrical specimens (3 mm height × 6 mm diameter) were prepared for each material (10 preheated, 10 control). The microhardness was determined at three time intervals: 10 minutes after mixing, after the ST as detected through the FTIR part of the study, and after one week. Knoop microhardness was assessed using a diamond indenter with a 25 g load and 15 seconds dwell time. Results: Ketac Universal showed an increase in temperatures of 15.7°C for powder and 3.6°C for liquid, while Equia Forte showed 16.4°C for powder and 8.5°C for liquid. FTIR spectra indicated that preheating reduced the ST for Equia Forte but increased it for Ketac Universal. Preheating increased the initial microhardness (T1) of Equia Forte. With maturation over one week, it was observed that preheating significantly improved the microhardness of both materials compared with the control specimens. Conclusion: Preheating influenced the ST and the microhardness of Ketac Universal and Equia Forte. The ST and microhardness of Ketac Universal increased after seven days, whereas Equia Forte showed a reduced ST and increased microhardness from the outset.

Optoacoustic imaging of gold nanorod based photothermal therapy

Gold Nanorod Photothermal Therapy (GNR-PTT) is a minimally invasive technique and an alternative to surgery for destroying tumors while sparing normal tissues. Gold Nanorods (GNRs) with strong extinction peaks in the near infra-red (NIR) spectrum is a good candidate to convert light into thermal energy to destroy tumors. Opto-acoustic imaging (OAI) is a non-invasive method that detects time-resolved acoustic waves created by short pulses of NIR in tissue. It leads to a pressure rise in the irradiated volume. The question of whether OAI is a suitable candidate for temperature monitoring of GNR-PTT in the NIR spectrum was examined. In this thesis, for the first time, GNRs in a gel phantom was used to monitor the temperature during PTT with different laser powers and GNR concentrations. The imaging was performed by a commercial device IMAGIO, Seno, TX. The results show changes of the OA signal follow to temperature changes. The concentration of GNR and the power have a significant role in producing good results.