Synthesis of electrical networks interconnecting PZT actuators to damp mechanical vibrations

This paper proves that it is possible to damp mechanical vibrations of some beam frames by means of piezoelectric actuators interconnected via passive networks. We create a kind of electromechanical wave guide where the electrical velocity group equals the mechanical one thus enabling an electromechanical energy transfer. Numerical simulations are presented which prove the technical feasibility of proposed deviceComment: International Symposium on Applied Electromagnetics and Mechanics in honor of Professor K.Miya, Tokyo: 2000. 9 page

Pseudo-Sylvester domains and skew laurent polynomials over firs

Building on recent work of Jaikin-Zapirain, we provide a homological criterion for a ring to be a pseudo-Sylvester domain, that is, to admit a division ring of fractions over which all stably full matrices become invertible. We use the criterion to study skew Laurent polynomial rings over free ideal rings (firs). As an application of our methods, we prove that crossed products of division rings with free-by-{infinite cyclic} and surface groups are pseudo-Sylvester domains unconditionally and Sylvester domains if and only if they admit stably free cancellation. This relies on the recent proof of the Farrell--Jones conjecture for normally poly-free groups and extends previous results of Linnell--L\"uck and Jaikin-Zapirain on universal localizations and universal fields of fractions of such crossed products

The compressive failure of graphite/epoxy plates with circular holes

The behavior of fiber reinforced composite plates containing a circular cutout was characterized in terms of geometry (thickness, width, hole diameter), and material properties (bending/extensional stiffness). Results were incorporated in a data base for use by designers in determining the ultimate strength of such a structure. Two thicknesses, 24 plies and 48 plies were chosen to differentiate between buckling and strength failures due to the presence of a cutout. Consistent post-buckling strength was exhibited by both laminate configurations

The use of fish silage in different composition for the growth of carp Cyprinus carpio L.

This study aims to examine the fish silage for total gain weight, growth rate, and the specific growth rate of common carp (Cyprinus carpio L.), which is cultivated in 12 nets (1x0,5x1m), with the density of 10 fish (3-5 cm) on each net. The experimental design used was a completely randomized design (CRD) with 4 treatments and 3 replications; treatment A with 10% fish silage, treatment B with fish silage 20%, treatment C with 30% fish silage and treatment D were commercial pellet. The ANOVA test showed that the treatment effect among feed A, B, C, and D tested did not give a significant difference to total gain weight, growth rate and the specific growth of carp fry.Keyword: common carp, fish silage, fish feed, growth ABSTRAKPenelitian ini bertujuan untuk menelaah pemberian silase ikan bagi pertumbuhan mutlak, pertumbuhan nisbi, dan pertumbuhan harian ikan mas (Cyprinus carpio L.), yang dipelihara dalam petak-petak jaring berukuran 1x 0,5 x 1 m, dengan padat penebaran 10 ekor ikan berukuran  3-5 cm. Rancangan percobaan yang digunakan adalah rancangan acak lengkap (RAL) dengan 4 perlakuan dan 3 ulangan; perlakuan A pelet berkomposisi silase ikan 10%, perlakuan B pelet berkomposisi silase ikan 20 %, perlakuan C pelet berkomposisi silase ikan 30 % dan perlakuan D adalah pelet komersil. Uji ANOVA menunjukkan bahwa pengaruh perlakuan di antara pakan A, B, C, dan D yang diujicobakan tidak memberikan perbedaan yang nyata terhadap pertumbuhan mutlak, pertumbuhan nisbi dan pertumbuhan harian benih ikan mas.Kata kunci : ikan mas, silase ikan, pakan ikan, pertumbuha

FAUNA BENTOS BERUKURAN LEBIH DARI 1MM DI MUARA SUNGAI SARIO, KOTA MANADO

Benthic fauna is a group of benthic organisms that live on the bottom of the water or bottom of sedimentary grounds or among sediments. This study aims to understand the distribution and types of benthic faunal organisms measuring > 1mm in the Sario river at a depth of 1-3 m. Benthos sampling was carried out using a grab sampler with three repetitions. The benthic sediment sample was sieved using a 1000 m (1.0 mm) sieve. The sediment retained in the sieve was identified based on its morphological characters using a stereomicroscope. Furthermore, the number of organisms found was counted and analyzed according to the calculation of the ecological index. The results of the identification of benthic faunal organisms >1mm got a total of 60 individuals from 9 families earning an average density of 222.1 ind/m2, Diversity Index 1.04 (medium category), Uniformity Index 0.47 (medium category), and Dominance Index 0.44 (no one dominates). Keywords: Benthic Fauna, Sario River, Density, Ecological Index Abstrak Fauna bentos merupakan kelompok organisme bentos yang hidup di dasar perairan atau dasar sedimen maupun di antara sedimen. Penelitian ini bertujuan untuk mendapatkan gambaran distribusi dan jenis organisme fauna bentos yang berukuran > 1mm di daerah muara sungai Sario pada kedalaman 1-3 m. Pengambilan sampel bentos dilakukan dengan menggunakan grab sampler dengan pengulangan sebanyak tiga kali. Sampel sedimen bentos diayak menggunakan saringan 1000 µm (1,0 mm). Sedimen yang tertahan di saringan kemudian diidentifikasi berdasarkan karakter morfologi dengan menggunakan bantuan mikroskop stereo. Selanjutnya jumlah organisme yang ditemukan dihitung dan dianalisis menurut perhitungan indeks ekologi. Hasil identifikasi organisme fauna bentos >1mm mendapatkan total 60 individu dari 9 famili mendapatkan hasil rata-rata kepadatan 222,1 ind/m2, Indeks Keanekaragaman 1,04 (kategori sedang), Indeks Keseragaman 0,47 (kategori sedang) dan Indeks Dominansi 0,44 (tergolong tidak ada yang mendominasi). Kata Kunci: Fauna bentos, Muara Sungai Sari, Kelimpahan, Indeks ekologi &nbsp

The Anderson transition: time reversal symmetry and universality

We report a finite size scaling study of the Anderson transition. Different scaling functions and different values for the critical exponent have been found, consistent with the existence of the orthogonal and unitary universality classes which occur in the field theory description of the transition. The critical conductance distribution at the Anderson transition has also been investigated and different distributions for the orthogonal and unitary classes obtained.Comment: To appear in Physical Review Letters. Latex 4 pages with 4 figure

Antibacterial Activity and Zoochemical Analysis of Sea Urchin Diadema setosum (Leske, 1778) Extract From Aertembaga Waters, Bitung City

Sea urchin is one of the marine biotas that produce bioactive compounds and has biological activity, one of which is antibacterial. This study aims to determine the antibacterial activity of the crude extract of D. setosum gonad and its fractionation against test bacteria Staphylococcus aureus and Escherichia coli and to conduct a zoochemical analysis to determine the content of bioactive compounds. The antibacterial test used the disc diffusion method while the chemical analysis was carried out qualitatively. The results showed that the methanol, ethyl acetate, and n-hexane fraction had antibacterial activity against the two test bacteria. The ethyl acetate fraction was the fraction that showed the highest antibacterial activity, its inhibition zone was 8 mm against S. aureus and 7,5 mm against E. coli. The zoochemical analyses of the ethyl acetate fraction from gonads extract showed positive results for alkaloid compound, phenolic, and saponinKeywords: Sea urchin Gonad, Antibacterial, Disc diffusion, Zoochemistry, ExtractionAbstrakBulu babi merupakan salah satu biota laut yang memproduksi senyawa bioaktif dan memiliki aktivitas biologis salah satunya adalah antibakteri. Tujuan penelitian ini mengetahui aktivitas antibakteri dari ekstrak kasar gonad bulu babi D. setosum dan hasil fraksinasi terhadap bakteri Staphylococcus aureus dan Escherichia coli serta melakukan analisis zookimia untuk mengetahui kandungan senyawa bioaktif. Pengujian antibakteri menggunakan metode difusi cakram sedangkan analisis kimia dilakukan secara kualitatif. Hasil penelitian menunjukkan baik fraksi metanol, fraksi etil asetat, dan fraksi n-heksana memiliki aktivitas antibakteri terhadap kedua bakteri uji. Fraksi etil asetat merupakan fraksi yang memperoleh aktivitas antibakteri tebaik dengan diameter zona hambat 8 mm terhadap bakteri S.aureus dan 7,5 mm terhadap bakteri E. coli. Hasil uji zookimia fraksi etil asetat menunjukkan bahwa ekstrak gonad D. setosum mengandung senyawa dari golongan alkaloid, fenolik, dan saponin.Kata kunci : Gonad Bulu Babi (D. setosum ), Antibakteri, difusi cakram, Zookimia, Ekstraks

The Use of Fish Silage in Different Composition for the Growth of Carp Cyprinus Carpio L.

Penelitian ini bertujuan untuk menelaah pemberian silase ikan bagi pertumbuhan mutlak, pertumbuhan nisbi, dan pertumbuhan harian ikan mas (Cyprinus carpio L.), yang dipelihara dalam petak-petak jaring berukuran 1x 0,5 x 1 m, dengan padat penebaran 10 ekor ikan berukuran 3-5 cm. Rancangan percobaan yang digunakan adalah rancangan acak lengkap (RAL) dengan 4 perlakuan dan 3 ulangan; perlakuan A pelet berkomposisi silase ikan 10%, perlakuan B pelet berkomposisi silase ikan 20 %, perlakuan C pelet berkomposisi silase ikan 30 % dan perlakuan D adalah pelet komersil. Uji ANOVA menunjukkan bahwa pengaruh perlakuan di antara pakan A, B, C, dan D yang diujicobakan tidak memberikan perbedaan yang nyata terhadap pertumbuhan mutlak, pertumbuhan nisbi dan pertumbuhan harian benih ikan mas

Metal-insulator transition in three dimensional Anderson model: universal scaling of higher Lyapunov exponents

Numerical studies of the Anderson transition are based on the finite-size scaling analysis of the smallest positive Lyapunov exponent. We prove numerically that the same scaling holds also for higher Lyapunov exponents. This scaling supports the hypothesis of the one-parameter scaling of the conductance distribution. From the collected numerical data for quasi one dimensional systems up to the system size 24 x 24 x infinity we found the critical disorder 16.50 < Wc < 16.53 and the critical exponent 1.50 < \nu < 1.54. Finite-size effects and the role of irrelevant scaling parameters are discussed.Comment: 4 pages, 2 figure