Sub-millimter and terahertz-wave packaging for large chip-width MMICs

We present novel waveguide packaging for sub-millimeter and terahertz-wave devices, which is suitable for large chip-width MMICs and doesn't require any additional fabrication process. With full electromagnetic simulation, we analyze possible wave modes in a rectangular waveguide with thin E-plane slits formed for inserting large-width MMICs into the split waveguide block and show that parasitic modes can be well suppressed by lossy and high-dielectric material. For a 1.1-mm-wide test IC in the 260-320 GHz band, measured transition loss is around 1 dB with more than 60 dB inter-port isolation.1154Ysciescopu

Local structural analyses on molten terbium fluoride in lithium fluoride and lithium–calcium fluoride mixtures

X-ray absorption fine structure (XAFS) measurements on terbium fluoride in molten lithium fluoride and in molten lithium–calcium fluoride mixtures, (e.g. 0.20TbF3–0.80LiF, 0.20TbF3–0.62LiF–0.18CaF2, 0.20TbF3–0.48LiF–0.32CaF2, 0.50TbF3–0.50LiF, and 0.50TbF3–0.38LiF–0.12CaF2), have been carried out. In the solid state, coordination number of terbium (Ni) and inter ionic distances between terbium and fluorine in the first neighbor (ri) are nearly constant in all mixtures. In 0.20TbF3–0.80LiF, 0.20TbF3–0.62LiF–0.18CaF2 and 0.50TbF3–0.50LiF mixtures, Ni's decrease from ca. 8 to 6 and ri's also decrease from ca. 2.29 to 2.26 Å on melting. On the other hands, in molten 0.20TbF3–0.48LiF–0.32CaF2 and 0.50TbF3–0.38LiF–0.12CaF2 mixtures, Ni's are slightly larger than 6 and ri's do not change. These facts correspond to the amount of F− supplied by solvent melts, i.e. the effect of CaF2 becomes predominant at bCaF2 > 0.32 in ternary 0.20TbF3–aLiF–bCaF2 mixtures and at bCaF2 > 0.12 in ternary 0.50TbF3–aLiF–bCaF2 mixtures

Sr(ii) extraction by crown ether in HFC: entropy driven mechanism through H₂PFTOUD

The solvent extraction of Sr(II) was carried out using dicyclohexano-18-crown-6 (DCH18C6) and two HFC mixed solvents MS1 and MS2, where MS1 was composed of 30/60 (w/w)% trans-1, 2-dichloroethylene/HFC-43 (HFC-43: 1, 1, 1, 2, 2, 3, 4, 5, 5, 5-decafluoropentane) and MS2 was 5/95 (w/w)% heptane/HFC-43. Nitric acid and perfuruoro-3-6-9-trioxaundecane-1, 11-dioic acid (H₂PFTOUD) were used to study the effect of acid on the extraction. The maximum distribution ratio of Sr(II) (DSr) observed for H2PFTOUD conditions was ∼180, and >10 times larger than aqueous nitric acid conditions. The DSr value was influenced by concentrations of the DCH18C6, Sr(II), and acid, and by temperature. The composition of extracted complexes was estimated using slope analysis as an Sr(II)–anion–DCH18C6 ratio of ∼1 : 2 : 1. From the extended X-ray absorption fine structure (EXAFS) measurements of Sr(II) in the aqueous and organic phases, it is inferred that regardless of the acid used, DCH18C6 coordinates to the first coordination sphere of the Sr(II) extracted complexes and Sr(II) is hydrated (complexation with H₂PFTOUD cannot be distinguished) in the aqueous phase. Thermodynamic data were significantly changed by choice of acid, i.e., both enthalpy and entropy values were negative for nitric acid conditions, on the other hand, entropy values were large and positive for H₂PFTOUD conditions. These results have demonstrated that the combination of HFC solvent and crown ether is applicable for metal extraction

Reverse loading tests of steel tube under biaxial stress states

Biaxial loading and reverse loading tests were performed using seamless carbon steel tubes. Biaxial stress components in the axial and circumferential directions were applied to the tubular specimens using a servo-controlled multiaxial tube expansion testing machine developed by Kuwabara and Sugawara (2013). The tubular specimens were loaded under linear tensile stress paths. Contours of plastic work were measured in the principal stress space, and the differential hardening (DH) behavior was observed; the shapes of the contours of plastic work changed with an increase in plastic work. In addition, small uniaxial tensile specimens were fabricated from the mother tube wall in axial and hoop directions, and tension–compression reverse loading tests were performed to quantitatively evaluate the Bauschinger effect of the test material. Moreover, bilinear stress path experiments were performed to investigate the effects of axial prestraining on the change in the Bauschinger effect; compressive preloading in the axial direction (first loading) was followed by the application of linear stress paths in the first quadrant of the principal stress space (second loading). The measured Bauschinger effect in the second loading was different from those measured in the uniaxial reverse loading tests for the as-received material. The material model will be utilized to improve the accuracy in the numerical analyses of the cold working processes for fabricating steel tubes

リフレクター近傍リクエストフィルタリングによるDRDoS攻撃回避

DRDoS攻撃のうちDNSamp攻撃では，リフレクターと呼ばれる踏み台サーバによってデータ量が大幅に増幅され，標的サーバやそのネットワークに負荷をかける．本研究では，増幅発生前の不正クエリの段階で攻撃パケットを遮断することが可能な，ISPが実装することを想定したシステムを開発した．本システムでは，プロバイダネットワークと利用者の境界に同じ機能を持つ機器を設置する．これらの機器の中で，リフレクター近傍の機器ではDNSクエリの増加を検知し，フィルタリングを行う．しかし，これにより標的サーバからリフレクターへの正規クエリを遮断する可能性がある．そのため，標的サーバ近傍の機器で正規通信に対してポート番号の変換を行うことにより，リフレクター近傍の機器での攻撃通信と正規通信の識別を可能とした．これにより，通信増加が正規クエリであった場合には通信を阻害することなく，DNSamp攻撃を約1.2秒程度で回避することができた