Automatic segmentation and classification of seven-segment display digits on auroral images

In this paper we describe a new and fully automatic method for segmenting and classifying digits in seven-segment displays. The method is applied to a dataset consisting of about 7 million auroral all-sky images taken during the time period of 1973–1997 at camera stations centred around Sodankylä observatory in northern Finland. In each image there is a clock display for the date and time together with the reflection of the whole night sky through a spherical mirror. The digitised film images of the night sky contain valuable scientific information but are impractical to use without an automatic method for extracting the date–time from the display. We describe the implementation and the results of such a method in detail in this pape

A scalable nanogenerator based on self-poled piezoelectric polymer nanowires with high energy conversion efficiency

Nanogenerators based on piezoelectric materials convert ever-present mechanical vibrations into electrical power for energetically autonomous wireless and electronic devices. Nanowires of piezoelectric polymers are particularly attractive for harvesting mechanical energy in this way, as they are flexible, lightweight and sensitive to small vibrations. Previous studies have focused exclusively on nanowires grown by electrospinning, but this involves complex equipment, and high voltages of $\approx$ 10 kV that electrically pole the nanowires and thus render them piezoelectric. Here we demonstrate that nanowires of poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) grown using a simple and cost-effective template-wetting technique, can be successfully exploited in nanogenerators without poling. A typical nanogenerator comprising $\approx$ 10$^{10}$ highly crystalline, self-poled, aligned nanowires spanning $\approx$ 2 cm$^2$ is shown to produce a peak output voltage of 3 V at 5.5 nA in response to low-level vibrations. The mechanical-to-electrical conversion efficiency of 11% exhibited by our template-grown nanowires is comparable with the best previously reported values. Our work therefore offers a scalable means of achieving high-performance nanogenerators for the next generation of self-powered electronics.SKN is grateful for support from the Royal Society through a Dorothy Hodgkin Fellowship. VN acknowledges the Herchel Smith Fund, University of Cambridge for a Fellowship. This work was supported by the EPSRC Cambridge NanoDTC, EP/G037221/1.This is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1002/aenm.20140051

Electrodynamics and energy characteristics of aurora at high resolution by optical methods

Technological advances leading to improved sensitivity of optical detectors have revealed that aurora contains a richness of dynamic and thin filamentary structures, but the source of the structured emissions is not fully understood. In addition, high resolution radar data have indicated that thin auroral arcs can be correlated with highly varying and large electric fields, but the detailed picture of the electrodynamics of auroral filaments is yet incomplete. The ASK instrument is a state-of-the-art ground-based instrument designed to investigate these smallest auroral features at very high spatial and temporal resolution, by using three EMCCDs in parallel for three different narrow spectral regions. ASK is specifically designed to utilize a new optical techique to determine the ionospheric electric fields. By imaging the long-lived O+ line at 732~nm, the plasma flow in the region can be traced, and since the plasma motion is controlled by the electric field, the field strength and direction can be estimated at unprecedented resolution. The method is a powerful tool to investigate the detailed electrodynamics and current systems around the thin auroral filaments. The two other ASK cameras provide information on the precipitation by imaging prompt emissions, and the emission brightness ratio of the two emissions, together with ion chemistry modeling, is used to give information on the energy and energy flux of the precipitating electrons. In this paper, we discuss these measuring techniques, and give a few examples of how they are used to reveal the nature and source of fine scale structuring in the auror

Observation of Confinement-Induced Self-Poling Effects in Ferroelectric Polymer Nanowires Grown by Template Wetting

Ferroelectric polymer nanowires grown using a template-wetting method are shown to achieve an orientated 'self-poled' structure resulting from the confined growth process. Self-poling is highly desirable as it negates the need for high electric fields, mechanical stretching and/or high temperatures typically associated with poling treatments in ferroelectric polymers, as required for piezoelectric and/or pyroelectric applications. Here, we present differential scanning calorimetry, infrared spectroscopy and dielectric permittivity measurements on as-fabricated template-grown polyvinylidene fluoride-trifluoroethylene (P(VDF-TrFE)) nanowires, and quantitatively compare the results with spin-cast films of the same composition that have been electrically poled, both before and after subsequent de-poling temperature treatment. The measurements reveal remarkably similar trends between the physical properties of the as-grown nanowires and the electrically poled film samples, providing insight into the material structure of the 'self-poled' nanowires. In addition, piezo-response force microscopy (PFM) data is presented that allow s for unambiguous identification of self-poling in ferroelectric polymer nanostructures, and indicates the suitability of the template-wetting approach in fabricating nanowires that can be used directly for piezoelectric/pyroelectric applications, without the need for post-deposition poling/processing.The authors are grateful for financial support from the European Research Council through an ERC Starting Grant (Grant no. ERC-2014-STG-639526, NANOGEN). R.A.W. thanks the EPSRC Cambridge NanoDTC, EP/G037221/1, for studentship funding.This is the author accepted manuscript. It is currently under an indefinite embargo pending publication by Wiley

Energy and flux variations across thin auroral arcs

Two discrete auroral arc filaments, with widths of less than 1 km, have been analysed using multi-station, multi-monochromatic optical observations from small and medium field-of-view imagers and the EISCAT radar. The energy and flux of the precipitating electrons, volume emission rates and local electric fields in the ionosphere have been determined at high temporal (up to 30 Hz) and spatial (down to tens of metres) resolution. A new time-dependent inversion model is used to derive energy spectra from EISCAT electron density profiles. The energy and flux are also derived independently from optical emissions combined with ion-chemistry modelling, and a good agreement is found. A robust method to obtain detailed 2-D maps of the average energy and number flux of small scale aurora is presented. The arcs are stretched in the north-south direction, and the lowest energies are found on the western, leading edges of the arcs. The large ionospheric electric fields (250 mV m?1) found from tristatic radar measurements are evidence of strong currents associated with the region close to the optical arcs. The different data sets indicate that the arcs appear on the boundaries between regions with different average energy of diffuse precipitation, caused by pitch-angle scattering. The two thin arcs on these boundaries are found to be related to an increase in number flux (and thus increased energy flux) without an increase in energ

LKP : Implementasi Aplikasi PRTG dalam Menyusun Traffic di Sebuah Jaringan Intranet pada PT. PERTAMINA (PERSERO)

Traffic jaringan adalah salah satu topik yang banyak dibicarakan saat ini. Banyaknya perangkat yang menggunakan teknologi jaringan membuat bidang ini juga semakin berkembang. Banyak perusahaan dan instansi memerlukan pengukuran traffic atau pengawasan traffic. Salah satunya adalah PT. Pertamina (Persero). PT. Pertamina (Persero) merupakan Badan Usaha Milik Negara yang ditugaskan Pemerintah untuk mengelola kegiatan Minyak dan Gas Bumi di Indonesia. Banyak sekali cabang-cabang perusahaan dari PT. Pertamina (Persero). Oleh karena itu PT. Pertamina (Persero) harus mengimplementasikan teknologi-teknologi terbaru. Salah satunya adalah teknologi Jaringan Komputer. Jaringan Komputer adalah sebuah system dimana beberapa device atau perangkat seperti computer , server , router , switch dihubungkan pada sebuah media yang dapat berupa kabel atau nirkabel. Manfaat dari jaringan computer adalah antar perangkat dapat berkomunikasi dengan saling menukar data melalui media dan perangkat pendukung jaringan computer. Kebutuhan akan jaringan komputer sangat penting, dimana di era globalisasi kebutuhan akan informasi sangat besar. Oleh karena itu Jaringan Komputer pada PT. Pertamina (Persero) harus di awasi, karena banyak sekali pengguna Jaringan Komputer pada perusahaan tersebut menggunakannya dengan tidak semestinya. Sehingga traffic data akan berjalan tidak stabil. Sehingga dengan dilaksanakannya kerja praktek ini, Jaringan Komputer pada PT Pertamina (Persero) diharapkan bisa di awasi dan di kontrol dengan baik. Dan hasil akhir dari kerja praktek ini adalah dibuatnya sebuah dasboard yang berisi kegiatan jaringan di PT. Pertamina (Persero)

Localized electromechanical interactions in ferroelectric P(VDF-TrFE) nanowires investigated by scanning probe microscopy

We investigate the electromechanical interactions in individual polyvinylidene fluoride-trifluoroethylene nanowires in response to localized electrical poling via a conducting atomic force microscope tip. Spatially resolved measurements of piezoelectric coefficients and elastic moduli before and after poling reveal a striking dependence on the polarity of the poling field, notably absent in thin films of the same composition. These observations are attributed to the unclamped nature of the nanowires and the inherent asymmetry in their chemical and electrical interactions with the tip and underlying substrate. Our findings provide insights into the mechanism of poling/switching in polymer nanowires critical to ferroelectric device performance.S.K.-N. and Y.C. are grateful for financial support from the European Research Council through an ERC Starting Grant (Grant No. ERC-2014-STG-639526, NANOGEN). R.A.W. thanks the EPSRC Cambridge NanoDTC, EP/G037221/1, for studentship funding. Q.J. is grateful for financial support through a Marie Sklodowska Curie Fellowship, H2020-MSCA-IF-2015-702868

NMDA receptor antagonists and pain relief: A meta-analysis of experimental trials

OBJECTIVES: We conducted a meta-analysis of controlled trials that used experimental models of acute pain and hyperalgesia to examine the analgesic effects of N-methyl-D-aspartate receptor (NMDAR) antagonists. METHODS: Six major databases were systematically searched (to 03/2018) for studies using human evoked pain models to compare NMDAR antagonists with no-intervention controls. Pain outcome data were analyzed with random-effects meta-analysis. RESULTS: Searches identified 70 eligible trials (N=1069). Meta-analysis found that low-dose ketamine (<1 mg/kg) produced a decrease in the size of hyperalgesic area (Standardized Mean Difference=0.54, CI95[0.34, 0.74], p<.001), and a 1.2-point decrease (CI95[0.88, 1.44], p<.001) in pain ratings from 4.6 to 3.4 on a 0-10 scale (a 26% reduction). Similar analgesia was observed for acute and hyperalgesic models and was constant across the dosing range (0.03-1.00 mg/kg). Moderate-high variability in effect size was observed and mild side effects (e.g. sedation, sensory disturbance) were common. No effects of dextromethorphan were found. CONCLUSIONS: Findings provide robust evidence for analgesic and anti-hyperalgesic effects of ketamine, supporting its utility for acute and chronic pain management. However, pain relief was modest, suggesting ketamine may potentially be most useful when opioids are contraindicated, rapid analgesia is required or for pain resistant to conventional medication