Fabrication of the 23-ft Collimating Mirror for the JPL 25-ft Space Simulator

Optical, structural, and thermal design criteria and fabrication techniques for collimating mirror in space simulato

Pembelajaran Enkripsi Metode Word Auto Key Encryption

Kriptografi Metode WAKE merupakan salah satu metode yang telah digunakan secara komersial. WAKE merupakan singkatan dari Word Auto Key Encryption. Metode ini ditemukan oleh David Wheeler pada tahun 1993 dan merupakan salah satu algoritma stream cipher yang cepat dalam implementasinya dalam perangkat lunak. Metode ini menggunakan kunci 128 bit, plaintext 32 bit dan sebuah tabel 256 x 32 bit. Dalam algoritmanya, metoda ini menggunakan operasi XOR, AND, OR dan Shift Right. Inti dari metode WAKE terletak pada proses pembentukan tabel S-Box dan proses pembentukan kunci. Tabel S-Box dari metode WAKE bersifat fleksibel dan berbeda-beda untuk setiap putaran. Perancangan perangkat lunak menggunakan metode perancangan RAD (Rapid Application Development), adapun langkah-langkah yang dilakukan yaitu : Bussiness Modeling, Data modelling, Process Modeling, GenerationApplicatio

An autopsy study of a fouled reverse osmosis membrane element used in a brackish water treatment plant

The fouling of a spiral wound reverse osmosis (RO) membrane after nearly 1 year of service in a brackish water treatment plant was investigated using optical and electron microscopic methods, Fourier transform infrared spectroscopy (FTIR) and inductively coupled plasma atomic emission spectrometry (ICP-AES). Both the top surface and the cross-section of the fouled membrane were analysed to monitor the development of the fouling layer. It has been found that the extent of fouling was uneven across the membrane surface with regions underneath or in the vicinity of the strands of the feed spacer being more severely affected. Fouling appeared to have developed through different stages. In particular, it consisted of an initial thin fouling layer of an amorphous matrix with embedded particulate matter. The amorphous matrix comprised organic–Al–P complexes and the particulate matter was mostly aluminium silicates. Subsequently, as the fouling layer reached a thickness of about 5–7 μm, further amorphous material, which is suggested to include extracellular polymeric substances such as polysaccharides, started to deposit on top of the existing fouling layer. This secondary amorphous material did not seem to contain any particulate matter nor any inorganic elements within it, but acted as a substrate upon which aluminium silicate crystals grew exclusively in the absence of other foulants, including natural organic matter (NOM

Probing the effect of point defects on the leakage blocking capability of Al0.1Ga0.9N/Si structures using a monoenergetic positron beam

Vacancy-type defects in Al0.1Ga0.9N were probed using a monoenergetic positron beam. Al0.1Ga0.9N layers with different carbon doping concentrations ([C] = 5 x 10(17) -8 x 10(19) cm(-3)) were grown on Si substrates by metalorganic vapor phase epitaxy. The major defect species in Al0.1Ga0.9N was determined to be a cation vacancy (or cation vacancies) coupled with nitrogen vacancies and/or with carbon atoms at nitrogen sites (C(N)s). The charge state of the vacancies was positive because of the electron transfer from the defects to C-N-related acceptors. The defect charge state was changed from positive to neutral when the sample was illuminated with photon energy above 1.8 eV, and this energy range agreed with the yellow and blue luminescence. For the sample with high [C], the charge transition of the vacancies under illumination was found to be suppressed, which was attributed to the trapping of emitted electrons by C-N-related acceptors. With increasing [C], the breakdown voltage under the reverse bias condition increased. This was explained by the trapping of the injected electrons by the positively charged vacancies and C-N-related acceptors

Comparative phenology of Acacia berlandieri, A. minuata, A. rigidula, A. schaffneri, and Chloroleucon ebano in the lower Rio Grande Valley of Texas

A phenological study of Acacia berlandieri, A. minuata, A. rigidula, A. schaffneri, and Chloroleucon ebano was conducted at three sites in the lower Rio Grande Valley of Texas from July 1998 to August 1999. Flowering in Acacia species occurred between January and April 1999, and was influenced by precipitation only in A. minuata . The timing of flowering appears to be influenced by the amount of time needed for fruit maturation. Precipitation, photoperiod, and temperature influenced the timing of fruiting in all species except A. berlandieri . Shoot elongation and leaf maturation in Acacia species were positively correlated with temperature and photoperiod

The Business Corporations Act of New Brunswick: Observations From A Management Perspective

New Brunswick has followed the lead of other Canadian jurisdictions by adopting a business corporations statute that simplifies the routine administration of corporate affairs while enlarging management accountability to shareholders and creditors. The author examines the new Business Corporations Act concentrating on the impact of the new proxnsions on directors, officers and controlling shareholders and highlighting the factors to be considered in the transition period during which letters patent companies may choose between remaining under the old legislation and continuing under the new.Se conformant à la direction de certaines juridictions canadiennes, le Nouveau-Brunswick a adopté une loi portant sur les corporations commerciales. La nouvelle Loi sur les corporations commerciales simplifie les affaires courantes des corporations tout en augmentant la responsabilitié de la gérance envers les actionnaires et les créanciers. L ’auteur étudit l’effet de ces nouvelles dispositions vis-à-vis les administrateurs, les dirigeants et les actionnaires majoritaires, en soulignant les éléments à considérés durant le période de transition. Pendant cette periode, les corporations formées en vertu des lettres patentes peuvent choisir de demeurer sous l’ancienne loi ou de suivre la nouvelle loi

A memory-efficient dynamic programming algorithm for optimal alignment of a sequence to an RNA secondary structure

BACKGROUND: Covariance models (CMs) are probabilistic models of RNA secondary structure, analogous to profile hidden Markov models of linear sequence. The dynamic programming algorithm for aligning a CM to an RNA sequence of length N is O(N(3)) in memory. This is only practical for small RNAs. RESULTS: I describe a divide and conquer variant of the alignment algorithm that is analogous to memory-efficient Myers/Miller dynamic programming algorithms for linear sequence alignment. The new algorithm has an O(N(2) log N) memory complexity, at the expense of a small constant factor in time. CONCLUSIONS: Optimal ribosomal RNA structural alignments that previously required up to 150 GB of memory now require less than 270 MB

A Model of the Statistical Power of Comparative Genome Sequence Analysis

Comparative genome sequence analysis is powerful, but sequencing genomes is expensive. It is desirable to be able to predict how many genomes are needed for comparative genomics, and at what evolutionary distances. Here I describe a simple mathematical model for the common problem of identifying conserved sequences. The model leads to some useful rules of thumb. For a given evolutionary distance, the number of comparative genomes needed for a constant level of statistical stringency in identifying conserved regions scales inversely with the size of the conserved feature to be detected. At short evolutionary distances, the number of comparative genomes required also scales inversely with distance. These scaling behaviors provide some intuition for future comparative genome sequencing needs, such as the proposed use of “phylogenetic shadowing” methods using closely related comparative genomes, and the feasibility of high-resolution detection of small conserved features