IMPLEMENTASI CHALLENGE RESPONSE AUTHENTICATION MECHANISM (CRAM) UNTUK KEAMANAN TRANSAKSI PERANGKAT IoT

This research aims to secure data transaction in Internet of Things (IoT)devices using the challenge-response authentication mechanism (CRAM). The research choose uses ESP 8266 and ESP 32 to develop the system for their ability to run micropython programming language. Using a random challenge to grant authentication protects the system from replay attack from intruders. In each authentication process, the client receives a 10 digit random number to be encrypted using a shared key and sent back to the server. The server then checks if the client posses the correct key by decrypting the encrypted challenge using the same shared key. Access is granted if the decryption result is equal to the original challenge

Arguments hydrogéochimiques en faveur de Trias évaporitique non affleurant dans le massif du Djurdjura (dorsale kabyle, élément des Maghrébides)

L'analyse des eaux pose à nouveau la question de l'importance des faciès gypso-salifères dans le Trias de la dorsale kabyle du Djurdjura. Cette dernière est un élément de l'orogène alpin périméditerranéen où le Trias est décrit comme étant formé essentiellement de grès et de pélites avec des niveaux marneux et dolomitiques. Dans les régions telliennes, plus méridionales, il est représenté par des formations marno-gypsifères de grande épaisseur (Trias tellien), en position tectonique constamment anormale. On ne rencontre généralement pas de formations évaporitiques en surface dans le massif du Djurdjura. Les analyses chimiques de la majorité des sources le confirment. Toutefois la source de Tinzert, dont l'impluvium est constitué essentiellement de calcaires montre un cortège d'éléments d'origine évaporitique (fortes teneurs en chlorures, sodium et sulfates et la présence du strontium) et plaide pour la présence de niveaux évaporitiques du Trias, à la base de l'aquifère drainé par cette source. Le rapport Sr2+/Ca2+ (en ‰) de la source de Tinzert (3 1000 mg·l-1), sodium (> 500 mg·l-1), sulfates (> 200 mg·l-1) and potassium (> 25 mg·l-1).During flood periods, because of dilution and quick conduit flows in the upper calcareous zones, the water type becomes calcium bicarbonate. During this period, waters flowing out of the spring are traced by the limestone shallow waters (transit of epikarstic waters). On top and upstream from Tinzert, less than 20 metres to the South, Tala Agouni Lansar displays a very different chemical type, calcium bicarbonate. This fact demonstrates that Tinzert sodium chloride content is acquired by water which stays in the deep saturated zone (Figs. 3 et 4), and that longitudinal faults divide the lithological units into segments.Analyses of strontium in waters demonstrate that most of the springs (ABDESSELAM, 1995) have low Sr2+ contents (0.06-0.23 mg·l-1). Tinzert spring has a much higher content (0.35-1.83 mg·l-1 ; Table 1). The use of the Sr2+ /Ca2+ ratio (‰) enabled us to distinguish among aquifers completely developed in limestones, others related to Triassic sandstones and one related to salty layers. The map of Sr2+ /Ca2+ ratios indicates that the springs related to Triassic outcrops have the higher values (Fig. 3).According to the Sr2+ /Ca2+ ratio (‰), three groups can be distinguished:- springs related to limestones, with no relationship with Triassic formations, have a low Sr2+/Ca2+ ratio ( 5‰) classifies this water into the category of waters originating from the alpine Triassic evaporites (MEYBECK, 1984). This high ratio is coupled with the high sulfate, and especially the chloride and sodium content of these waters. This spring is situated on the trace of a north-east thrust sheet sole that probably includes Triassic in its lower part, which concerns the whole Haïzer massif of about 8 km. The water transit is probably either in the upper thrust sheet, or in the lower one, following the East-West axis lowering of the structure.The springs of the Djurdjura display well-differentiated hydrochemical responses. Several springs that only drain limestone have a standard calcium bicarbonate chemical type (Sr2+/Ca2+ < 1 ‰). Other springs (Sr2+/Ca2+ =1 - 1.5 ‰) are characteristic of waters that have flowed in the sandstone and dolomitic Triassic layers, which are observed on the outcrops. Tinzert spring at least, which drains the middle part of the limestone range (Fig. 4, Sr2+/Ca2+=3 - 8.77 ‰), is characterised by waters which have transited through the evaporitic Triassic. The waters of Tinzert spring have also high chloride, sodium and sulfate contents.In the Djurdjura, where evaporitic Triassic formations do not generally outcrop, except in very small lenses, an argument can be made for the existence of deep evaporitic Triassic deposits on the basis of the hydrochemical response of perennial springs

A Hybrid Achromatic Metalens

Metalenses, ultra-thin optical elements that focus light using subwavelength structures, have been the subject of a number of recent investigations. Compared to their refractive counterparts, metalenses offer reduced size and weight, and new functionality such as polarization control. However, metalenses that correct chromatic aberration also suffer from markedly reduced focusing efficiency. Here we introduce a Hybrid Achromatic Metalens (HAML) that overcomes this trade-off and offers improved focusing efficiency over a broad wavelength range from 1000-1800 nm. HAMLs can be designed by combining recursive ray-tracing and simulated phase libraries rather than computationally intensive global search algorithms. Moreover, HAMLs can be fabricated in low-refractive index materials using multi-photon lithography for customization or using molding for mass production. HAMLs demonstrated diffraction limited performance for numerical apertures of 0.27, 0.11, and 0.06, with average focusing efficiencies greater than 60% and maximum efficiencies up to 80%. A more complex design, the air-spaced HAML, introduces a gap between elements to enable even larger diameters and numerical apertures

KUALITAS SINYAL DAN KINERJA JARINGAN DATA ANTAR LORA GATEWAY RFM95

Tujuan penelitian ini menganalisis kualitas sinyal dan kinerja jaringan data antar LoRa gateway RFM95 dalam kondisi Line Of Sight. Posisi antar pemancar dan penerima saat pengukuran berada pada jarak 100 m, 200 m, 500 m dan 700 m menggunakan antenna gain 2 dB dan daya pancar 10 dbm. Perubahan Spreading Factor diterapkan untuk mendapatkan parameter-parameter yang mempengaruhi kinerja sistem LoRa yaitu antara lain RSSI terhadap jarak, SNR terhadap jarak, Packet Delivery Ratio terhadap jarak, Delay terhadap jarak, Delay terhadap panjang paket dan perbandingan perhitungan transmission delay terhadap hasil pengukuran delay. Hasil pengujian memberikan informasi bahwa RSSI menurun terhadap jarak sedangkan Spreading Factor tidak terlalu mempengaruhi RSSI. Parameter lainnya yaitu SNR dipengaruhi oleh jarak, kondisi noise pada kanal area pengukuran dan Spreading Factor. Packet Delivery Ratio menurun ketika jarak bertambah tetapi dengan menggunakan SF 9 menunjukan hasil yang lebih bagus dibandingkan dengan menggunakan SF 7, terlihat pada jarak 700m dengan SF 9 mempunyai PDR 76% sedangkan dengan SF 7 mempunyai PDR 44%. Delay dipengaruhi oleh panjang paket dan penggunaan SF9 menghasilkan delay yang lebih besar daripada SF 7 terlihat pada jarak 700m dengan SF9 menghasilkan delay 0.996678 s dan SF 7 menghasilkan delay 0.060945s&nbsp

Proceedings of the workshop "Standard Model at the LHC" University College London 30 March - 1 April 2009

Proceedings from a 3-day discussion on Standard Model discoveries with the first LHC dataComment: 9 contributions to the proceedings of the LHC Standard Model worksho

A New Scintillator Tile/Fiber Preshower Detector for the CDF Central Calorimeter

A detector designed to measure early particle showers has been installed in front of the central CDF calorimeter at the Tevatron. This new preshower detector is based on scintillator tiles coupled to wavelength-shifting fibers read out by multi-anode photomultipliers and has a total of 3,072 readout channels. The replacement of the old gas detector was required due to an expected increase in instantaneous luminosity of the Tevatron collider in the next few years. Calorimeter coverage, jet energy resolution, and electron and photon identification are among the expected improvements. The final detector design, together with the R&D studies that led to the choice of scintillator and fiber, mechanical assembly, and quality control are presented. The detector was installed in the fall 2004 Tevatron shutdown and started collecting colliding beam data by the end of the same year. First measurements indicate a light yield of 12 photoelectrons/MIP, a more than two-fold increase over the design goals.Comment: 5 pages, 10 figures (changes are minor; this is the final version published in IEEE-Trans.Nucl.Sci.