RCA Satcom: In-orbit experience

The system characteristics of the Satcom batteries and Satcom power system are briefly discussed. Performance of the nickel cadmium 22 cell batteries onboard in parallel with independent redundant charges providing the charge rates is reported. Performance onboard reconditioning with individual cell bypasses with 1 ohm resistors is discussed for the F-1 and F-2 spacecraft

Tracking Users across the Web via TLS Session Resumption

User tracking on the Internet can come in various forms, e.g., via cookies or by fingerprinting web browsers. A technique that got less attention so far is user tracking based on TLS and specifically based on the TLS session resumption mechanism. To the best of our knowledge, we are the first that investigate the applicability of TLS session resumption for user tracking. For that, we evaluated the configuration of 48 popular browsers and one million of the most popular websites. Moreover, we present a so-called prolongation attack, which allows extending the tracking period beyond the lifetime of the session resumption mechanism. To show that under the observed browser configurations tracking via TLS session resumptions is feasible, we also looked into DNS data to understand the longest consecutive tracking period for a user by a particular website. Our results indicate that with the standard setting of the session resumption lifetime in many current browsers, the average user can be tracked for up to eight days. With a session resumption lifetime of seven days, as recommended upper limit in the draft for TLS version 1.3, 65% of all users in our dataset can be tracked permanently.Comment: 11 page

A Comparison of Accuracy of Image- versus Hardware-based Tracking Technologies in 3D Fusion in Aortic Endografting

OBJECTIVES: Fusion of three-dimensional (3D) computed tomography and intraoperative two-dimensional imaging in endovascular surgery relies on manual rigid co-registration of bony landmarks and tracking of hardware to provide a 3D overlay (hardware-based tracking, HWT). An alternative technique (image-based tracking, IMT) uses image recognition to register and place the fusion mask. We present preliminary experience with an agnostic fusion technology that uses IMT, with the aim of comparing the accuracy of overlay for this technology with HWT. METHOD: Data were collected prospectively for 12 patients. All devices were deployed using both IMT and HWT fusion assistance concurrently. Postoperative analysis of both systems was performed by three blinded expert observers, from selected time-points during the procedures, using the displacement of fusion rings, the overlay of vascular markings and the true ostia of renal arteries. The Mean overlay error and the deviation from mean error was derived using image analysis software. Comparison of the mean overlay error was made between IMT and HWT. The validity of the point-picking technique was assessed. RESULTS: IMT was successful in all of the first 12 cases, whereas technical learning curve challenges thwarted HWT in four cases. When independent operators assessed the degree of accuracy of the overlay, the median error for IMT was 3.9 mm (IQR 2.89-6.24, max 9.5) versus 8.64 mm (IQR 6.1-16.8, max 24.5) for HWT (p = .001). Variance per observer was 0.69 mm(2) and 95% limit of agreement ±1.63. CONCLUSION: In this preliminary study, the error of magnitude of displacement from the "true anatomy" during image overlay in IMT was less than for HWT. This confirms that ongoing manual re-registration, as recommended by the manufacturer, should be performed for HWT systems to maintain accuracy. The error in position of the fusion markers for IMT was consistent, thus may be considered predictable

PERANCANGAN MODEL BISNIS “Barber ON“ : E-MARKETPLACE UNTUK BARBERSHOP

Potensi perkembangan penyedia layanan potong rambut secara online di Indonesia masih terbuka sangat lebar. Penetrasi teknologi internet dan perangkat internet bergerak yang cukup tinggi berperan penting dalam terbentuknya era digital saat ini yang semakin mempersingkat jarak antara pemasar dan konsumen targetnya, Perubahan zaman ke era digital pun lebih cepat dirasakan dan tidak dapat dihindari. Fakta membuktikan jumlah pengguna internet di Indonesia terus meningkat dengan pesat setiap tahunnya. Laporan hasil survei pada tahun 2017 oleh Asosiasi Penyelenggara Jasa Internet Indonesia (APJII) mencatat sebanyak 143 juta jiwa penduduk Indonesia telah terhubung dengan internet. Kemudian, berdasarkan hasil survei APJII tahun 2017 penetrasi pengguna internet di Indonesia sebesar 54,68 persen dari total populasi penduduk Indonesia 262,2 juta jiwa. Pertumbuhan penetrasi pengguna internet di Indonesia selama 7 tahun kebelakang cukup besar dimana dari 42 juta jiwa di tahun 2010 meningkat pesat di tahun 2017 yang tercatat 143,26 juta jiwa. Berdasarkan jenis kelaminnya penetrasi pengguna internet pria adalah sebesar 51,43 persen. Melihat peluang tersebut Barber ON mengajukan suatu model bisnis, yaitu aplikasi smartphone yang dapat di kustomisasi untuk mempermudah konsumen agar dapat terhubung dengan para barber yang kebanyakan berasal dari kampung ASGAR (asli Garut). Pasar untuk Barber ON pada tahap awal ini ditargetkan untuk penduduk pria Tangerang Selatan dengan rentang umur 20-49 tahun. Data BPS tahun 2017 mencatat sebanyak 416,126 pria pada rentang umur tersebut di Indonesia. Dengan investasi awal sebesar Rp 1.037.000.000, payback period diproyeksikan dalam waktu 4 tahun 3 bulan dengan NPV Rp 498.837.021,44 dan IRR 23% pada kondisi most likely

Economic feasibility study of solar PV and wind turbines in Morocco applying Monte Carlo simulation

In this work, an economic feasibility study has been conducted on solar PV and wind turbine in Morocco using Monte Carlo simulation. By using historical measured data of solar irradiance and wind speed on different cities across Morocco and taking into account other factors that may affect the results on the economic profitability of the previously mentioned renewable plants, many different outcomes were computed to help interested parties take decisions on this type of activity. First, a review on the regulatory framework of the country has been done. Later, using solar irradiance and wind speed data of each city, probability distribution functions were assigned on each city, which allowed to consider the meteorological uncertainties in the calculations. The tools used to discuss the results are the net present value (NPV) and the levelized cost of electricity (LCOE). A comparison has been done between the solar PV with different tracking configurations and the onshore wind turbine at different levels of power capacity. The results reveal that regions close to the desert are more suitable to implement solar PV related projects, and the southern coastal regions are better befitting for wind turbines. This work is an academic research and results are computed using theoretical methods

From Artifacts to Outcomes: Comparison of HMD VR, Desktop, and Slides Lectures for Food Microbiology Laboratory Instruction

Despite the value of VR (Virtual Reality) for educational purposes, the instructional power of VR in Biology Laboratory education remains under-explored. Laboratory lectures can be challenging due to students' low motivation to learn abstract scientific concepts and low retention rate. Therefore, we designed a VR-based lecture on fermentation and compared its effectiveness with lectures using PowerPoint slides and a desktop application. Grounded in the theory of distributed cognition and motivational theories, our study examined how learning happens in each condition from students' learning outcomes, behaviors, and perceptions. Our result indicates that VR facilitates students' long-term retention to learn by cultivating their longer visual attention and fostering a higher sense of immersion, though students' short-term retention remains the same across all conditions. This study extends current research on VR studies by identifying the characteristics of each teaching artifact and providing design implications for integrating VR technology into higher education