Dispersion-engineered silicon nitride waveguides for mid-infrared supercontinuum generation covering the wavelength range 0.8-6.5 mu m

We numerically demonstrate the generation of a mid-infrared supercontinuum (SC) through the design of an on-chip complementary metal oxide semiconductor (CMOS) compatible 10-mm-long air-clad rectangular waveguide made using stoichiometric silicon nitride (Si 3 N 4 ) as the core and MgF 2 glass as its lower cladding. The proposed waveguide is optimized for pumping in both the anomalous and all-normal dispersion regimes. A number of waveguide geometries are optimized for pumping at 1.55 μ m with ultrashort pulses of 50-fs duration and a peak power of 5 kW. By initially keeping the thickness constant at 0.8 μ m, four different structures are engineered with varying widths between 3 μ m and 6 μ m. The largest SC spectral evolution covering a region of 0.8 μ m to beyond 6.5 μ m could be realized by a waveguide geometry with a width of 3 μ m. Numerical analysis shows that increasing width beyond 3 μ m by fixing thickness at 0.8 μ m results in a reduction of the SC extension in the long wavelength side. However, the SC spectrum can be enhanced beyond 6.5 μ m by increasing the waveguide thickness beyond 0.9 μ m with the same peak power and pump source. To the best of our knowledge, this is first time report of a broad SC spectral evolution through numerical demonstration in the mid-infrared region by the silicon nitride waveguide. In the case of all-normal dispersion pumping, a flatter SC spectra can be predicted with the same power and pump pulse but with a reduced bandwidth spanning 950–2100 nm

Realisability Semantics for Intersection Types and Expansion Variables

Expansion was invented at the end of the 1970s for calculating principal typings for $\lambda$-terms in type systems with intersection types. Expansion variables (E-variables) were invented at the end of the 1990s to simplify and help mechanise expansion. Recently, E-variables have been further simplified and generalised to also allow calculating type operators other than just intersection. There has been much work on denotational semantics for type systems with intersection types, but none whatsoever before now on type systems with E-variables. Building a semantics for E-variables turns out to be challenging. To simplify the problem, we consider only E-variables, and not the corresponding operation of expansion. We develop a realisability semantics where each use of an E-variable in a type corresponds to an independent degree at which evaluation occurs in the $\lambda$-term that is assigned the type. In the $\lambda$-term being evaluated, the only interaction possible between portions at different degrees is that higher degree portions can be passed around but never applied to lower degree portions. We apply this semantics to two intersection type systems. We show these systems are sound, that completeness does not hold for the first system, and completeness holds for the second system when only one E-variable is allowed (although it can be used many times and nested). As far as we know, this is the first study of a denotational semantics of intersection type systems with E-variables (using realisability or any other approach)

Oracle Inequalities and Optimal Inference under Group Sparsity

We consider the problem of estimating a sparse linear regression vector $\beta^*$ under a gaussian noise model, for the purpose of both prediction and model selection. We assume that prior knowledge is available on the sparsity pattern, namely the set of variables is partitioned into prescribed groups, only few of which are relevant in the estimation process. This group sparsity assumption suggests us to consider the Group Lasso method as a means to estimate $\beta^*$. We establish oracle inequalities for the prediction and $\ell_2$ estimation errors of this estimator. These bounds hold under a restricted eigenvalue condition on the design matrix. Under a stronger coherence condition, we derive bounds for the estimation error for mixed $(2,p)$-norms with $1\le p\leq \infty$. When $p=\infty$, this result implies that a threshold version of the Group Lasso estimator selects the sparsity pattern of $\beta^*$ with high probability. Next, we prove that the rate of convergence of our upper bounds is optimal in a minimax sense, up to a logarithmic factor, for all estimators over a class of group sparse vectors. Furthermore, we establish lower bounds for the prediction and $\ell_2$ estimation errors of the usual Lasso estimator. Using this result, we demonstrate that the Group Lasso can achieve an improvement in the prediction and estimation properties as compared to the Lasso.Comment: 37 page

Study of Unconventional Alternatives to Vertical Breakwater

The main objective of the breakwaters is to protect the port, the beach or the beach facilities from strong waves and storms, as they help to establish calm inside the port and thus achieve safety for ships, and ease of operation. This research aims to present study unconventional alternatives to vertical breakwater. In this study, two different models of vertical wave barriers implemented were chosen for their study and evaluation of the hydrodynamic performance. The first model is a vertical wall with circular slots and the second model is a vertical wall with square slots. A comparison was made between the two models it was found that the square slots reduce the transmission of waves more than circular slots by 5 to 20%. The use of two circular slotted walls decreases wave transmission by up to 30% and increases wave energy dissipation by up to 40% as compared to a single wall. With increasing relative length (h/L), the horizontal wave force rises. The relative wave forces (F/Fo), at porosity ( ) =0.25, was greater than at porosity ( ) = 0.50 by 10 to 30%. At the openings, the wave velocity is high, and the wave energy dissipation factor was also high; the higher the wave amplitude, the greater the wave energy dissipation factor

Ultra-broadband mid-infrared supercontinuum generation using chalcogenide rib waveguide

The ultrabroadband mid-infrared (MIR) supercontinuum (SC) generation using dispersion-tailored Ge11.5As24Se64.5 chalcogenide (ChG) glass rib-waveguide has been investigated numerically. An air-clad 1-cm-long rib-waveguide employing MgF2 glass for its lower cladding shows that an ultrabroadband MIR SC spanning from 1.8 to 8 μm and extending over more than 2 octave could be generated with a relatively low peak power of 0.5 kW pumped at a wavelength of 3.1 μm. Our estimated bandwidth is the largest reported so far for SC generated using ChG rib-waveguide pumped at a wavelength of 3.1 μm with a low peak power of 0.5 kW. We carry out simulations by varying peak power ranges between 0.1 and 3 kW. Our analysis through rigorous numerical simulations show that SC can be extended further into the MIR up to 10 μm using the same pump pulses with a relatively modest peak power of 3 kW

PENGEMBANGAN LEMBAR KERJA PESERTA DIDIK BIOLOGI BERBASIS KETERAMPILAN PROSES SAINS PADA KELAS XI SMA NEGERI 1 PANGKEP

Kurikulum 2013 mensyaratkan kemampuan keterampilan proses sains harus dimiliki peserta didik dalam pembelajaran serta menuntut guru dapat mengembangkan bahan ajar yang memacu keaktifan dalam kelas. Diperlukan suatu pendekatan dan sumber belajar yang tepat. Pendekatan Keterampilan Proses Sains dan Lembar Kerja Peserta Didik (LKPD) dapat disatukan untuk menjawab masalah diatas. Rumusan masalah pada penelitian ini adalah (i) Bagaimana mengembangkan Lembar Kerja Peserta Didik (LKPD) berbasis Keterampilan Proses Sains pada mata pelajaran Biologi kelas XI SMA ? (ii) Bagaimanakah validitas, kepraktisan, dan efektifitas Lembar Kerja Peserta Didik (LKPD) berbasis Keterampilan Proses Sains pada mata pelajaran Biologi kelas XI SMA? Tujuan penelitian ini adalah (i) Untuk mengembangkan Lembar Kerja Peserta Didik (LKPD) Berbasis Keterampilan Proses Sains pada mata pelajaran Biologi kelas XI SMA. (ii) Untuk mengetahui Lembar Kerja Peserta Didik (LKPD) berbasis Keterampilan Proses Sains pada mata pelajaran Biologi kelas XI SMA yang memenuhi kriteria Valid, Praktis, dan Efektif yang telah dikembangkan. Penelitian ini adalah penelitian pengembangan (Research and development). Penelitian dan pengembangan adalah usaha untuk merancang dan mengembangkan produk baru.. Model pengembangan yang digunakan untuk mengembangkan LKPD berbasis KPS adalah model pengembangan ADDIE (Analysis, Design, Development, Implementation, and Evaluation). Lokasi penelitian di SMA Negeri 1 Pangkep. Subjek penelitian adalah kelas XI MIA 2. Hasil penelitian menunjukkan bahwa nilai rata-rata total kevalidan LKPD berbasis KPS adalah 4,26 berada dalam kategori valid. Persentase rata-rata nilai respon peserta didik adalah 87,46% berada pada kategori sangat baik dan respon peserta didik terhadap LKPD adalah positif. Sedangkan persentase rata-rata nilai respon guru 100% berada pada kategori sangat kuat dengan respon terhadap LKPD adalah positif. Hasil belajar peserta didik sebesar 90,32% mencapai KKM sehingga dikatakan efektif. Kesimpulannya adalah LKPD berbasis KPS pada materi sistem ekskresi yang dikembangkan adalah valid, praktis, efektif Kata Kunci: LKPD Biologi, Keterampilan Proses Sains