Evaluation of numerical integration schemes for a partial integro-differential equation

Numerical methods are important in computational neuroscience where complex nonlinear systems are studied. This report evaluates two methodologies, finite differences and Fourier series, for numerically integrating a nonlinear neural model based on a partial integro-differential equation. The stability and convergence criteria of four finite difference methods is investigated and their efficiency determined. Various ODE solvers in Matlab are used with the Fourier series method to solve the neural model, with an evaluation of the accuracy of the approximation versus the efficiency of the method. The two methodologies are then compared

Synergistic effects of ultraviolet radiation, thermal cycling, and atomic oxygen on altered and coated Kapton surfaces

The photovoltaic (PV) power system for Space Station Freedom (SSF) uses solar array blankets which provide structural support for the solar cells and house the electrical interconnections. In the low Earth orbital (LEO) environment where SSF will be located, surfaces will be exposed to potentially damaging environmental conditions including solar ultraviolet (UV) radiation, thermal cycling, and atomic oxygen. It is necessary to use ground based tests to determine how these environmental conditions would affect the mass loss and optical properties of candidate SSF blanket materials. Silicone containing, silicone coated, and SiO(x) coated polyimide film materials were exposed to simulated LEO environmental conditions to determine there durability and whether the environmental conditions of UV, thermal cycling and oxygen atoms act synergistically on these materials. A candidate PV blanket material called AOR Kapton, a polysiloxane polyimide cast from a solution mixture, shows an improvement in durability to oxygen atoms erosion after exposure to UV radiation or thermal cycling combined with UV radiation. This may indicate that the environmental conditions react synergistically with this material, and the damage predicted by exposure to atomic oxygen alone is more severe than that which would occur in LEO where atomic oxygen, thermal cycling and UV radiation are present together

Helianthus inexpectatus (Asteraceae), a Tetraploid Perennial New Species from Southern California

Helianthus inexpectatus is described as a new species from the Newhall Ranch of northern Los Angeles County, California. It is a tetraploid (2n = 68) perennial that is morphologically similar to--—and intermediate in some characters between--—the diploid H. nuttallii and the hexaploid H. californicus

Mengalami Sang Misteri Melalui Liturgi Suci: Menggali Pesan Pastoral Berdasarkan Telaah Historis-teologis

Katolisisme mengajarkan bahwa “Allah adalah Misteri”. Meskipun Ia Yang “Transenden” itu senantiasa berusaha membuat diri-Nya dapat terjangkau oleh manusia melalui inisiatif kompasionis-Nya dengan berinkarnasi sebagai Allah Putra (mewujud dalam Yesus Kristus), Ia tetap Allah yang “Misteri”. Sebab, Allah dan karya-Nya yang agung, secara mutlak selalu mengungguli segala rumus dan paham insani yang terbatas. Karenanya, umat beriman mengalami kesukaran untuk berinteraksi dan mengalami Dia. Padahal, iman mengandaikan relasi/intimitas dengan Allah yang diimani. Bahkan, untuk beriman dengan mantap, manusia sebagai “makhluk simbolik”, senantiasa membutuhkan berbagai macam instrumen atau sarana yang dapat dicerap secara inderawi, sesuatu yang mewujud (memiliki form). Gereja memiliki sarana pengungkapan “Misteri” itu, yakni liturgi suci. Liturgi, dengan segala artifisialitas sekaligus divinitasnya, menjadi salah satu bentuk/sarana terbaik yang mampu menyentuh “sensus religiosum” umat. Melalui kajian historisteologis atas aspek misteri dalam liturgi yang disajikan dalam tulisan ini, diharapkan bahwa liturgi semakin mampu membantu umat berimanmerasakan dan mengimani benar bahwa Allah itu eksis, imanen, dan sangat mengasihi mereka

Simulation of the synergistic low Earth orbit effects of vacuum thermal cycling, vacuum UV radiation, and atomic oxygen

In order to assess the low Earth orbit (LEO) durability of candidate space materials, it is necessary to use ground laboratory facilities which provide LEO environmental effects. A facility combining vacuum thermal cycling and vacuum ultraviolet (VUV) radiation has been designed and constructed at NASA Lewis Research Center for this purpose. This facility can also be operated without the VUV lamps. An additional facility can be used to provide VUV exposure only. By utilizing these facilities, followed by atomic oxygen exposure in an RF plasma asher, the effects of the individual vacuum thermal cycling and VUV environments can be compared to the effect of the combined vacuum thermal cycling/VUV environment on the atomic oxygen durability of materials. The synergistic effects of simulated LEO environmental conditions on materials were evaluated by first exposing materials to vacuum thermal cycling, VUV, and vacuum thermal cycling/VUV environments followed by exposure to atomic oxygen in an RP plasma asher. Candidate space power materials such as atomic oxygen protected polyimides and solar concentrator mirrors were evaluated using these facilities. Characteristics of the Vacuum Thermal Cycling/VUV Exposure Facility which simulates the temperature sequences and solar ultraviolet radiation exposure that would be experienced by a spacecraft surface in LEO are discussed. Results of durability evaluations of some candidate space power materials to the simulated LEO environmental conditions will also be discussed. Such results have indicated that for some materials, atomic oxygen durability is affected by previous exposure to thermal cycling and/or VUV exposure

Evaluation of thermal control coatings for use on solar dynamic radiators in low Earth orbit

Thermal control coatings with high thermal emittance and low solar absorptance are needed for Space Station Freedom (SSF) solar dynamic power module radiator (SDR) surfaces for efficient heat rejection. Additionally, these coatings must be durable to low earth orbital (LEO) environmental effects of atomic oxygen, ultraviolet radiation and deep thermal cycles which occur as a result of start-up and shut-down of the solar dynamic power system. Eleven candidate coatings were characterized for their solar absorptance and emittance before and after exposure to ultraviolet (UV) radiation (200 to 400 nm), vacuum UV (VUV) radiation (100 to 200 nm) and atomic oxygen. Results indicated that the most durable and best performing coatings were white paint thermal control coatings Z-93, zinc oxide pigment in potassium silicate binder, and YB-71, zinc orthotitanate pigment in potassium silicate binder. Optical micrographs of these materials exposed to the individual environmental effects of atomic oxygen and vacuum thermal cycling showed that no surface cracking occurred

Penerapan Model Pembelajaran Kooperatif Tipe Stad (Student Teams Achievement Divisions)berbantuaan Lks (Lembar Kerja Siswa) Berkarakter Untuk Meningkatkan Aktivitas Belajar Dan Kemampuan Kognitif Fisika Siswa

Tujuan yang hendak dicapai dalam penelitian ini adalah mengetahui penerapan model pembelajaran kooperatif tipe Student Team Achievement Divisions (STAD) berbantuan LKS Berkarakter dalam meningkatkan aktivitas belajar dan kemampuan kognitif Fisika siswa kelas VIII.F SMP Negeri 16 Surakarta Tahun Ajaran 2012/2013 pada materi Gaya.Penelitian ini merupakan Penelitian Tindakan Kelas (Classroom Action Research) dengan model Kurt Lewin dan model Kolaboratif yang dilaksanakan dalam tiga siklus. Setiap siklus diawali tahap persiapan kemudian dilanjutkan tahap pelaksanaan, tahap pengamatan dan tahap refleksi. Subyek penelitian adalah siswa kelas VIII.F SMP Negeri 16 Surakarta Tahun Ajaran 2012/2013 sebanyak 24 siswa dengan penelitian dikhususkan pada materi Gaya. Data diperoleh melalui pengamatan, wawancara dan diskusi dengan guru, observer dan siswa, pre-test & post-test, catatan observer, kamera & handycam dan kajian dokumen. Data-data dari hasil penelitian diolah dan dianalisis secara kualitatif yang dilakukan dalam tiga komponen yaitu reduksi data, penyajian data dan penarikan kesimpulan.Berdasarkan hasil penelitian, dapat disimpulkan bahwapenerapan model pembelajaran kooperatif tipe Student Teams Achievement Divisions (STAD) berbantuan LKS berkarakter dapat meningkatkan aktivitas belajar siswa dan kemampuan kognitif siswa pada materi Gaya kelas VIII.F SMP Negeri 16 Surakarta tahun pelajaran 2012/2013.Hal ini dapat dilihat dari hasil pengamatan aktivitas belajar pada tiap siklus. Dari indikator aktivitas yang ditentukan terjadi peningkatan aktivitas belajar positif tiap siklus, dari 65,7% di siklus I menjadi 73,76% di siklus II dan 75,47% di siklus III.Kemampuan kognitif siswa juga meningkat dalam setiap siklus dengan peningkatan nilai rata-rata pre-test ke post-test, yakni 31,67 menjadi 60,83 dengan rata-rata gain ternormalisasi 0,42 pada siklus I, 48,95 menjadi 72,91 dengan rata-rata gain ternormalisasi 0,46 pada siklus II dan 29,58 menjadi 81,25 dengan rata-rata gain ternormalisasi 0,73 pada siklus III