20,176 research outputs found
Multi-Gigabit Wireless data transfer at 60 GHz
In this paper we describe the status of the first prototype of the 60 GHz
wireless Multi-gigabit data transfer topology currently under development at
University of Heidelberg using IBM 130 nm SiGe HBT BiCMOS technology. The 60
GHz band is very suitable for high data rate and short distance applications as
for example needed in the HEP experments. The wireless transceiver consist of a
transmitter and a receiver. The transmitter includes an On-Off Keying (OOK)
modulator, an Local Oscillator (LO), a Power Amplifier (PA) and a BandPass
Filter (BPF). The receiver part is composed of a BandPass- Filter (BPF), a Low
Noise Amplifier (LNA), a double balanced down-convert Gilbert mixer, a Local
Oscillator (LO), then a BPF to remove the mixer introduced noise, an
Intermediate Amplifier (IF), an On-Off Keying demodulator and a limiting
amplifier. The first prototype would be able to handle a data-rate of about 3.5
Gbps over a link distance of 1 m. The first simulations of the LNA show that a
Noise Figure (NF) of 5 dB, a power gain of 21 dB at 60 GHz with a 3 dB
bandwidth of more than 20 GHz with a power consumption 11 mW are achieved.
Simulations of the PA show an output referred compression point P1dB of 19.7 dB
at 60 GHz.Comment: Proceedings of the WIT201
Gradient discretization of Hybrid Dimensional Darcy Flows in Fractured Porous Media with discontinuous pressures at the matrix fracture interfaces
We investigate the discretization of Darcy flow through fractured porous
media on general meshes. We consider a hybrid dimensional model, invoking a
complex network of planar fractures. The model accounts for matrix-fracture
interactions and fractures acting either as drains or as barriers, i.e. we have
to deal with pressure discontinuities at matrix-fracture interfaces. The
numerical analysis is performed in the general framework of gradient
discretizations which is extended to the model under consideration. Two
families of schemes namely the Vertex Approximate Gradient scheme (VAG) and the
Hybrid Finite Volume scheme (HFV) are detailed and shown to satisfy the
gradient scheme framework, which yields, in particular, convergence. Numerical
tests confirm the theoretical results. Gradient Discretization; Darcy Flow,
Discrete Fracture Networks, Finite Volum
Effect of sampling rate and record length on the determination of stability and control derivatives
Flight data from five aircraft were used to assess the effects of sampling rate and record length reductions on estimates of stability and control derivatives produced by a maximum likelihood estimation method. Derivatives could be extracted from flight data with the maximum likelihood estimation method even if there were considerable reductions in sampling rate and/or record length. Small amplitude pulse maneuvers showed greater degradation of the derivative maneuvers than large amplitude pulse maneuvers when these reductions were made. Reducing the sampling rate was found to be more desirable than reducing the record length as a method of lessening the total computation time required without greatly degrading the quantity of the estimates
SCOPe: Structural Classification of Proteins--extended, integrating SCOP and ASTRAL data and classification of new structures.
Structural Classification of Proteins-extended (SCOPe, http://scop.berkeley.edu) is a database of protein structural relationships that extends the SCOP database. SCOP is a manually curated ordering of domains from the majority of proteins of known structure in a hierarchy according to structural and evolutionary relationships. Development of the SCOP 1.x series concluded with SCOP 1.75. The ASTRAL compendium provides several databases and tools to aid in the analysis of the protein structures classified in SCOP, particularly through the use of their sequences. SCOPe extends version 1.75 of the SCOP database, using automated curation methods to classify many structures released since SCOP 1.75. We have rigorously benchmarked our automated methods to ensure that they are as accurate as manual curation, though there are many proteins to which our methods cannot be applied. SCOPe is also partially manually curated to correct some errors in SCOP. SCOPe aims to be backward compatible with SCOP, providing the same parseable files and a history of changes between all stable SCOP and SCOPe releases. SCOPe also incorporates and updates the ASTRAL database. The latest release of SCOPe, 2.03, contains 59 514 Protein Data Bank (PDB) entries, increasing the number of structures classified in SCOP by 55% and including more than 65% of the protein structures in the PDB
Engineered bidirectional communication mediates a consensus in a microbial biofilm consortium
Microbial consortia form when multiple species colocalize and communally generate a function that none is capable of alone. Consortia abound in nature, and their cooperative metabolic activities influence everything from biodiversity in the global food chain to human weight gain. Here, we present an engineered consortium in which the microbial members communicate with each other and exhibit a “consensus” gene expression response. Two colocalized populations of Escherichia coli converse bidirectionally by exchanging acyl-homoserine lactone signals. The consortium generates the gene-expression response if and only if both populations are present at sufficient cell densities. Because neither population can respond without the other's signal, this consensus function can be considered a logical AND gate in which the inputs are cell populations. The microbial consensus consortium operates in diverse growth modes, including in a biofilm, where it sustains its response for several days
Effectiveness of sediment control structure : reducing nonpoint-source pollution entering a rural housing development lake in Mercer county, Pennsylvania
For the past two decades, water quality of both natural and man-made lakes has been a major environmental concern. Numerous studies suggest that land use patterns and/or storm water runoff are major factors in nutrient loading and bacterial contamination of freshwater lakes. In 1986, the Property Owners Association at Lake Latonka in Jackson Center, Pa., installed three sediment control structures in an attempt to reduce the amount of nonpoint-source pollution entering the lake. The Association installed a fourth structure in 1988. It has yet to be determined if any improvement in the water quality has occurred due to the control structures or to the possible changes in the agricultural activities surrounding the development.
From nine years of water quality monitoring data acquired from the consulting firm hired by the Property Owners Association, the percent reduction was determined by calculating the difference between the influx and outflow, dividing by the influx and multiplying by 100. The percent reduction was determined for each of the five water quality parameters (fecal coliform bacteria, ammonia, nitrate, phosphate and total solids). The mean percent reduction over the nine year monitoring period for each Sediment Control Structure and four control streams (Manito, Mohican, Park and Apache) were compared for each parameter. The total inorganic nitrogen and phosphate was also determined to provide a basis of comparison to other wetland systems recieving agricultural runoff.
Throughout the nine year monitoring period, there was a gradual improvement in the water quality entering the lake. All four sediment control structures demonstrated varying abilities to reduce coliform bacteria, nitrate, phosphate and suspended sediment. The structures were not able to reduce ammonia concentrations, most likely due to vegetative decay within the retention basins
The fractional Keller-Segel model
The Keller-Segel model is a system of partial differential equations
modelling chemotactic aggregation in cellular systems. This model has blowing
up solutions for large enough initial conditions in dimensions d >= 2, but all
the solutions are regular in one dimension; a mathematical fact that crucially
affects the patterns that can form in the biological system. One of the
strongest assumptions of the Keller-Segel model is the diffusive character of
the cellular motion, known to be false in many situations. We extend this model
to such situations in which the cellular dispersal is better modelled by a
fractional operator. We analyze this fractional Keller-Segel model and find
that all solutions are again globally bounded in time in one dimension. This
fact shows the robustness of the main biological conclusions obtained from the
Keller-Segel model
Fabrication of alignment structures for a fiber resonator by use of deep-ultraviolet lithography
We present a novel method to mount and align an optical-fiber-based resonator
on the flat surface of an atom chip with ultrahigh precision. The structures
for mounting a pair of fibers, which constitute the fiber resonator, are
produced by a spin-coated SU-8 photoresist technique by use of deep-UV
lithography. The design and production of the SU-8 structures are discussed.
From the measured finesses we calculate the coupling loss of the SU-8
structures acting as a kind of fiber splice to be smaller than 0.013 dB.Comment: 4 pages, 3 figure
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