Second-order sensitivity of parallel shear flows and optimal spanwise-periodic flow modifications

The question of optimal spanwise-periodic modification for the stabilisation of spanwise-invariant flows is addressed. A 2nd-order sensitivity analysis is conducted for the linear temporal stability of parallel flows U0 subject to small-amplitude spanwise-periodic modification e*U1, e<<1. Spanwise-periodic modifications have a quadratic effect on stability, i.e. the 1st-order eigenvalue variation is zero. A 2nd-order sensitivity operator is computed from a 1D calculation, allowing one to predict how eigenvalues are affected by any U1, without actually solving for modified eigenvalues/eigenmodes. Comparisons with full 2D stability calculations in a plane channel flow and in a mixing layer show excellent agreement. Next, optimisation is performed on the 2nd-order sensitivity operator: for each eigenmode streamwise wavenumber and base flow modification spanwise wavenumber b, the most stabilising profiles U1 are computed, together with lower bounds for the variation in leading eigenvalue. These bounds increase like b^-2 as b goes to 0, yielding a large stabilising potential. However, 3D modes with wavenumbers |b0|=b and b/2 are destabilised, thus larger control wavenumbers should be preferred. The modification U1 optimised for the most unstable streamwise wavenumber has a stabilising effect on other streamwise wavenumbers too. Finally, the potential of transient growth to amplify perturbations and stabilise the flow is assessed. Combined optimal perturbations that achieve the best balance between transient linear amplification and flow stabilisation are determined. In the mixing layer with b<1.5, these combined optimal perturbations appear similar to transient growth-only optimal perturbations, and achieve a more efficient overall stabilisation than optimal 1D and 2D modifications computed for stabilisation only. This is consistent with the efficiency of streak-based control strategies.Comment: 23 pages, 15 figure

Tinjauan Yuridis Tindak Pencemaran Nama Baik Melalui Media Sosial Berdasarkan Pasal 27 Ayat (3) Undang-undang Nomor 11 Tahun 2008 Tentang Informasi Dan Transaksi Elektronik Dikaitkan Dengan Kebebasan Berpendapat

Globalization era that we encounter has been the mark of technology growth itself. Globalization became the catalyst for the information technology era to be born. The stream that spread around the world nowdays causing changes in all aspect of human life, especially in developing nations, including Indonesia. In years now, motive of crime also developing in many forms, on of them is defamation, slander, and libel via social media, in Indonesia this is known as one of the cyber crimes. And has been obliged under law as state in Article of section (3) of Act No. 11 of 2008 stating Informastion and Electronic Transaction. The freedom of speech which has been regulated under of Act Perss No 40 of 1999, is the rights of every humas but it should be taking every responsibly just as stated on the Article 19 of Universal Declaration of Human Right and Acticle 29 in United Nations (UN)

From Dimensional Reduction of 4d Spin Foam Model to Adding Non-Gravitational Fields to 3d Spin Foam Model

A Kaluza-Klein like approach for a 4d spin foam model is considered. By applying this approach to a model based on group field theory in 4d (TOCY model), and using the Peter-Weyl expansion of the gravitational field, reconstruction of new non gravitational fields and interactions in the action are found. The perturbative expansion of the partition function produces graphs colored with su(2) algebraic data, from which one can reconstruct a 3d simplicial complex representing space-time and its geometry; (like in the Ponzano-Regge formulation of pure 3d quantum gravity), as well as the Feynman graph for typical matter fields. Thus a mechanism for generation of matter and construction of new dimensions are found from pure gravity.Comment: 11 pages, no figure, to be published in International Journal of Geometric Methods in Modern Physic

Intravitreal Bevacizumab for Photodynamic Therapy-Induced Massive Macular Detachment in Acute Central Serous Chorioretinopathy

We present a long followed up case of acute central serous chorioretinopathy (CSC) complicated by a severe visual loss due to massive pigment epithelium detachment of the macula after a full-dose photodynamic therapy (PDT). Rapid anatomical and functional improvement was observed after a single intravitreal injection of bevacizumab. To our knowledge, we report the first case of PDT-treated CSC complicated by severe visual loss. We can only speculate that the serous detachment of the posterior pole might have been caused by PDT-induced VEGF overexpression, explaining such an impressive response to Avastin treatment

Gross Margin Analysis and Constraints Faced by Small Scale Rice Producers in the West Region of Cameroon

This study was carried out to analyze gross margin and constraints faced by small scale rice producers in the West Region of Cameroon. A multistage stratified random sampling technique was used in selecting the respondents. A total of 192 small scale rice producers were purposively selected from four (4) out of eight divisions. Data were collected using structured questionnaires and interview schedule, administered on the respondents were analyzed using descriptive statistics. The Results indicated that an average small scale rice farmer obtained a gross margin of 67,000 fcfa per hectare despite high cost of fertilizer and agrochemical (16.82 percent); Poor marketing systems (13.55 percent); Insect and disease attack (13.28 percent); Poor infrastructure (13.28 percent); poor storage facility (12.84 percent); limited access to credit (11.78 percent); Lack of improved varieties of seeds (6.90 percent); land tenure system (6.73 percent) and lack of extension agents (4.78 percent) were identified to be the major constraints in small scale rice production in the West Region of Cameroon. However, to increase farmers’ gross margin in the studied area, it is recommended that Agro processing industries should be established in the studied area with aimed at reducing the cost of fertilizers and agrochemicals. Keyswords: Gross Margin, Constraints, Small scale producers, Cameroo

Analisis Pajak Hotel dalam Paradigma Pelayanan Publik untuk Meningkatkan Pendapatan Asli Daerah Kota Batu

: There various ways conducted by government for the welfare of its people, one of them is to seek capital from the community itself and return it to the community as well. While on the other hand the services to the taxpayersprovided by the government, sometimes less maximum. Thus, it is necessary to investigate the public services to hotel taxpayersas well as the resisting factor in supporting public services. The research method used qualitative research with the types and sources of data included primary and secondary data. The collection of data through observation, interviews, and documentation. The research instrument includedthe researchers themselves, interview, and field notes, purposive sampling technique including sampling, and informants of government officials in the public Revenue agency. The validity of the data used triangulation techniques. Analysis was by reduction, presentation, and conclusionswithdrawing. Batu\u27s Local Revenue Agency (DISPENDA) has conducted its services to the taxpayer well in accordance with Regulation No. 25 of 2009 on Public Service. The supporting factors included: good communication has been done, the ability of service personnels were good. Meanwhile the resisting factors included: inadequatefacilities, infrastructure and operating facilities as obliged byRegulation No. 25 of 2009 on Public Service. Keywords: Taxes, Public Services, Local Revenu