Solitons in a parametrically driven damped discrete nonlinear Schr\"odinger equation

We consider a parametrically driven damped discrete nonlinear Schr\"odinger (PDDNLS) equation. Analytical and numerical calculations are performed to determine the existence and stability of fundamental discrete bright solitons. We show that there are two types of onsite discrete soliton, namely onsite type I and II. We also show that there are four types of intersite discrete soliton, called intersite type I, II, III, and IV, where the last two types are essentially the same, due to symmetry. Onsite and intersite type I solitons, which can be unstable in the case of no dissipation, are found to be stabilized by the damping, whereas the other types are always unstable. Our further analysis demonstrates that saddle-node and pitchfork (symmetry-breaking) bifurcations can occur. More interestingly, the onsite type I, intersite type I, and intersite type III-IV admit Hopf bifurcations from which emerge periodic solitons (limit cycles). The continuation of the limit cycles as well as the stability of the periodic solitons are computed through the numerical continuation software Matcont. We observe subcritical Hopf bifurcations along the existence curve of the onsite type I and intersite type III-IV. Along the existence curve of the intersite type I we observe both supercritical and subcritical Hopf bifurcations.Comment: to appear in "Spontaneous Symmetry Breaking, Self-Trapping, and Josephson Oscillations in Nonlinear Systems", B.A. Malomed, ed. (Springer, Berlin, 2012

Influence of ultrafiltration membrane characteristics on adsorptive fouling with dextrans

This paper presents a detailed investigation of fouling mechanisms for ultrafiltration membranes with polysaccharides obtained by studying membrane–solute (static adsorption) and membrane–solute–solute interactions (ultrafiltration (UF)). Two polyethersulfone (PES) membranes and one stabilized cellulose (cellulosic) membrane with a nominal cut-off of 10 kg/mol and dextrans with average molar mass (M) of 4, 10 and 15 kg/mol were used. The membranes before and after static adsorption of dextran were characterized by captive bubble contact angle and tangential streaming potential measurements as well as ultrafiltration sieving curves for polyethylene glycols. Significant water flux reductions (4–15%), which also correlated with dextran molar mass, and changes of the other membrane characteristics occurred after static dextran adsorption for the PES membranes. An empirical model to describe the correlation between the relative water flux reduction and the concentration of solute had also been proposed. In contrast, no significant changes could be detected for the cellulosic membrane. Significant membrane–solute interactions had also been confirmed in the ultrafiltration experiments with dextrans where irreversible fouling had been observed for the PES but not for the cellulosic membranes. The results provide fundamental information for a better understanding of fouling by polysaccharides. In particular, it had been confirmed that hydrophilic and neutral dextrans can significantly foul PES membranes via adsorption to the surface of the membrane polymer. On this basis, methods for control of this fouling can be properly developed

Discrete solitons in electromechanical resonators

We consider a parametrically driven Klein--Gordon system describing micro- and nano-devices, with integrated electrical and mechanical functionality. Using a multiscale expansion method we reduce the system to a discrete nonlinear Schrodinger equation. Analytical and numerical calculations are performed to determine the existence and stability of fundamental bright and dark discrete solitons admitted by the Klein--Gordon system through the discrete Schrodinger equation. We show that a parametric driving can not only destabilize onsite bright solitons, but also stabilize intersite bright discrete solitons and onsite and intersite dark solitons. Most importantly, we show that there is a range of values of the driving coefficient for which dark solitons are stable, for any value of the coupling constant, i.e. oscillatory instabilities are totally suppressed. Stability windows of all the fundamental solitons are presented and approximations to the onset of instability are derived using perturbation theory, with accompanying numerical results. Numerical integrations of the Klein--Gordon equation are performed, confirming the relevance of our analysis

Peran Kepemimpinan Chief Information Officer (CIO) Dalam Penyelerasan Strategi TI Dan Bisnis

Pemanfaatan teknologi informasi pada Perusahaan atau organisasi sudah banyak dilakukan. Namun demikian penggunaannya masih sebatas pada tingkat teknis atau operasional dan belum sepenuhnya mendukung proses bisnis yang ada. Dibutuhkan seorang CIO yang mampu menyeleraskan strategi TI dengan strategi bisnis agar Perusahaan atau organisasi mampu bertahan hidup di lingkungan bisnis yang kompetitif. Namun ada beberapa hambatan yang dihadapi oleh seorang CIO, salah satunya terdapat “dinding pemisah” antara CIO dan staf TI. Dibutuhkan peran kepemimpinan CIO dan kompetensi soft skill sehingga bisa menghilangkan sekat pemisah demi terwujudnya keselarasan strategi TI dan bisnis yang lebih matang

Fluxon analogues and dark solitons in linearly coupled Bose-Einstein condensates

Two effectively one-dimensional parallel coupled Bose-Einstein condensates in the presence of external potentials are studied. The system is modelled by linearly coupled Gross-Pitaevskii equations. In particular, grey-soliton-like solutions representing analogues of superconducting Josephson fluxons as well as coupled dark solitons are discussed. Theoretical approximations based on variational formulations are derived. It is found that the presence of a magnetic trap can destabilize the fluxon analogues. However, stabilization is possible by controlling the effective linear coupling between the condensates.Comment: 14 pages, 7 figures, The paper is to appear in Journal of Physics

Fatigue Correstion Behavious of AISI 304 Stainles Steel in 3.5% NaCl Solution

Failuredue to corrosion fatigue is a phenomenon that often occurs in thestructure associated with a corrosive environment. Stepuse ofmaterialssuch as AISI 304 stainlesshas been done, buta failuredue to corrosion fatigue phenomena still occur and can not be understood and explained by the experts. This study focused on assessing changes in behaviorof AISI 304stainless steelareexperiencingrepeatedloadingincorrosive environment. The behavior changes observed with fatigue testing in laboratory air and 3.5% NaCl solution, using a fatigue testing machine typerotary bending, specimens weremadeaccording to ASTME-466 andASTMF-1801 for corrosionfatiguetesting.Fatigue testing presented in S-Ncurve and fracture patterns observed, observed in3.5% NaCl solution and constantstress 369.53 MP apitgrowth measurements done on sevenl evels and four levels of cycles for corrosion potential and current measurements a represented in the polarizationcurve. The results showe dthat the endurance limit of the laboratoryair environment at stress 323.34MPa and 3.5% NaCl solution decreases, up to stress 277.15 MPa at1.7x107cycles. Ductile fracture pattern is in the airand 3.5% NaCl solutionis brittle. Pits and cracks growth, failure is dominated by crack propagation and increase the number of cycles resulting in decreased surface potential and corrosion current density increases

Analisis Pengendalian Kualitas Statistika Pada Proses Produksi Pipa Electric Resistance Welded (ERW) Di PT. X

Pengendalian kualitas dalam industri manufaktur sangat diperlukan agar produk yang dihasilkan sesuai dengan standar yang telah ditetapkan dan mampu bersaing. PT. X yang memproduksi berbagai jenis pipa baja, salah satunya adalah pipa Electric Resistance Welded (ERW). Namun dalam prosesnya, bagian Quality Control belum menerapkan peta kendali statistika untuk pemecahan masalah melalui Statistical Process Control (SPC). Pengendalian kualitas yang dilakukan melibatkan tiga karakteristik kualitas pipa ERW yaitu diameter, panjang, dan berat pipa ERW. Pengendalian terhadap mean proses menggunakan Peta Kendali T2Hotelling, sedangkan untuk pengendalian variabilitasnya menggunakan Peta Kendali Generalized Variance. Penelitian ini membagi data menjadi dua tahap. Berdasarkan proses produksi pipa ERW dengan menggunakan peta kendali peta kendali T2Hotelling dan peta kendali Generalized Variance terdapat pengamatan yang out of control. Faktor Penyebabnya utama proses tidak terkendali antara lain faktor utama yaitu manusia karena kesalahan dalam pengukuran. Hasil indeks kapabilitas proses pipa ERW menunjukkan kapabilitas proses dari karakteristik kualitas produksi pipa ERW secara multivariat sudah kapabel dan variasi proses lebih kecil toleransi dari batas spesifikasi yang ditentukan. Nilai indeks kapabilitas Cpm tahap II lebih kecil daripada indeks kapabilitas tahap

Karakterisasi Resistensi Gulma Synedrella Nodiflora terhadap Herbisida Reflex Menggunakan Gen Ppx2l sebagai Penanda Molekuler

Fomesafen as an active substance of Reflex herbicide can inhibit PPOase, an enzyme playing important role in chlorophyl biosynthesis. Deletion of three bases at gene encoding PPOase, i.e. PPX2L, was reported as one of resistance mechanisms against PPOase inhibiting herbicides. Nevertheless, only a few studies on molecular characterization of Synedrella nodiflora resistance against Reflex were reported. Therefore, this study was aimed to (1) know the sequence of PPX2L gene isolated from resistant S. nodiflora against Reflex, (2) perform homology study of PPX2L gene from resistant S. nodiflora and various plant species in data base, and (3) know the sequence of PPX2L gene responsible to S. nodiflora resistance against Reflex. The PCR products of susceptible S. nodiflora showed three bands, in that of 500 bp is strongly assumed as PPX2L gene. Susceptible S. nodiflora is genetically different from susceptible A. tuberculatus, indicated by the absence of three base pairs at position 834, 835 and 836 in susceptible S. nodiflora, where in susceptible A. tuberculatus this position is occupied by CAG. Then, in both susceptible S. nodiflora and A. tuberculatus there is C at position 919 but T in resistant A. tuberculatus. At amino acid level this position is CCC (proline) in susceptible S. nodiflora, CTA (leucine) in susceptible A. tuberculatus and TTA (leucine) in resistant A. tuberculatus. Therefore, inspite of base alteration from C in susceptible A. tuberculatus to T in resistant A. tuberculatus, the amino acid formed remains constant, i.e. leucine. Significant difference is, however, observed in susceptible S. nodiflora because there is proline at the same posistion