10,342 research outputs found
Impedance Matched Absorptive Thermal Blocking Filters
We have designed, fabricated and characterized absorptive thermal blocking
filters for cryogenic microwave applications. The transmission line filter's
input characteristic impedance is designed to match and its
response has been validated from 0-to-50\,GHz. The observed return loss in the
0-to-20\,GHz design band is greater than dB and shows graceful
degradation with frequency. Design considerations and equations are provided
that enable this approach to be scaled and modified for use in other
applications
QCD Viscosity to Entropy Density Ratio in the Hadronic Phase
Shear viscosity (eta) of QCD in the hadronic phase is computed by the coupled
Boltzmann equations of pions and nucleons in low temperatures and low baryon
number densities. The eta to entropy density ratio eta/s maps out the nuclear
gas-liquid phase transition by forming a valley tracing the phase transition
line in the temperature-chemical potential plane. When the phase transition
turns into a crossover, the eta/s valley gradually disappears. We suspect the
general feature for a first-order phase transition is that eta/s has a
discontinuity in the bottom of the eta/s valley. The discontinuity coincides
with the phase transition line and ends at the critical point. Beyond the
critical point, a smooth eta/s valley is seen. However, the valley could
disappear further away from the critical point. The eta/s measurements might
provide an alternative to identify the critical points.Comment: 16 pages, 4 figures. Minor typos corrected and references adde
Ising metamagnets in thin film geometry: equilibrium properties
Artificial antiferromagnets and synthetic metamagnets have attracted much
attention recently due to their potential for many different applications.
Under some simplifying assumptions these systems can be modeled by thin Ising
metamagnetic films. In this paper we study, using both the Wang/Landau scheme
and importance sampling Monte Carlo simulations, the equilibrium properties of
these films. On the one hand we discuss the microcanonical density of states
and its prominent features. On the other we analyze canonically various global
and layer quantities. We obtain the phase diagram of thin Ising metamagnets as
a function of temperature and external magnetic field. Whereas the phase
diagram of the bulk system only exhibits one phase transition between the
antiferromagnetic and paramagnetic phases, the phase diagram of thin Ising
metamagnets includes an additional intermediate phase where one of the surface
layers has aligned itself with the direction of the applied magnetic field.
This additional phase transition is discontinuous and ends in a critical end
point. Consequently, it is possible to gradually go from the antiferromagnetic
phase to the intermediate phase without passing through a phase transition.Comment: 8 figures, accepted for publication in Physical Review
Second Cluster Integral and Excluded Volume Effects for the Pion Gas
The quantum mechanical formula for Mayer's second cluster integral for the
gas of relativistic particles with hard-core interaction is derived. The proper
pion volume calculated with quantum mechanical formula is found to be an order
of magnitude larger than its classical evaluation.
The second cluster integral for the pion gas is calculated in quantum
mechanical approach with account for both attractive and hard-core repulsive
interactions. It is shown that, in the second cluster approximation, the
repulsive pion-pion-interactions as well as the finite width of resonances give
important but almost canceling contributions. In contrast, an appreciable
deviation from the ideal gas of pions and pion resonances is observed beyond
the second cluster approximation in the framework of the Van der Waals
excluded-volume model.Comment: 29 pages, Latex, 9 PS-figure
Seasonal root changes and their relationships to leaf production and persistency of growth in some grasses and clovers : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Field Husbandry at Massey University, by 550 [D.E. Yen]
The seasonal behaviour of pasture plant species is of fundamental importance to the farmer as one of the indices of value of any particular species, and the uses to which it can be put; and to the plant breeder, since it is his primary object to produce pasture plants which suit the farmer under his particular system of farming. To illustrate this point specifically, the example of the ideals aimed at in the breeding of short rotation ryegrass in New Zealand may be cited. Quoting Levy (1945), "... Italian ryegrass is a one- to two-year plant for the temporary pasture, and the true perennial ryegrass can be used widely in rotational and permanent pastures. There is, however, too large a gap between true perennial ryegrass and true Italian ryegrass, and many years of breeding and selection within these species accentuated the gap rather than reduced it." It can be seen that the short rotation system of farming, incorporating pasture leys of 3-4 years was not well served in the choice of a suitable ryegrass. Thus the plant breeding section of the Grasslands Division (Department of Scientific and Industrial Research) turned its attention towards breeding by hybridisation of perennial and Italian ryegrass, a type that would possess as far as possible the desirable qualities of these two species in combination; that is, it would combine some of the rapid establishment, high winter and early spring growth and palatability of Italian ryegrass with an appreciable degree of persistency of perennial ryegrass. Seasonal growth thus played the major part in the objectives of the resultant programme from which short rotation ryegrass was produced. Comparative trials of yields of the three grasses, perennial, Italian and short rotation ryegrasses were conducted in different localities, serving a very important purpose in providing farmers with direct information regarding the seasonal characteristics of production of the new type. These trials, which are continuing, show that short rotation ryegrass conforms largely to the objectives aimed at, so that the requirement s of the man farming under short rotation system have been met, to a great extent, by the work of the plant breeder. [From Introduction
A short note on the presence of spurious states in finite basis approximations
The genesis of spurious solutions in finite basis approximations to operators
which possess a continuum and a point spectrum is discussed and a simple
solution for identifying these solutions is suggested
Perancangan Aplikasi E-Commerce Untuk Meningkatkan Penjualan Kain Tenun Ikat Fanny Art Shop
Fanny Art shop is a business engaged in the sale of woven fabrics typical of NTT. At present the sales process that runs at the fanny art shop is face to face or the buyer must come directly to the shop, and also product marketing at the Fanny Art shop is still relatively minimal because they still use social media such as Facebook and Instagram, this causes only only a handful of people can view sales posts. This is motivated by the rapid development of information technology and the large number of business people who market their products through E-commerce as a medium for online sales. Therefore, a promotional media and online sales based on an e-commerce website for the sale of woven textiles were designed. This design and manufacture is intended to facilitate sales and promotions, as well as to make it easier for consumers to choose East Nusa Tenggara woven woven models, without having to come to the shop in person, especially during the Covid-19 pandemic. In the process of developing this E-Commerce website using the Php and Mysql programming languages and the technique used is waterfall. The data flow method used is a structured method consisting of Data Flow Diagrams (DFD) to describe the functional model and Entity Relationship Diagram (ERD) to describe the data model as well as the testing technique using Blackbox testing. The goal to be achieved from developing this E-Commerce Web is to make it easier for buyers to make transactions wherever the buyer is without having to come directly to the Fanny Art Shop.Fanny Art shop merupakan sebuah usaha yang bergerak dibidang penjualan Kain tenun khas NTT. Saat ini proses penjualan yang berjalan pada toko fanny art shop adalah face to face atau pembeli harus datang langsung ke toko tersebut, dan juga pemasaran produk pada toko Fanny Art shop masih tergolong minim karena masih menggunakan media sosal seperti facebook dan instagaram hal ini yang menyebabkan hanya segelintir orang saja yang dapat meliahat postingan penjualan. Dilatar belakangi oleh perkembangan teknologi informasi yang begitu pesat serta, banyaknya para pelaku usaha yang memasarkan produk melalui E-commerce sebagai media penjualan online. Oleh karena itu maka dirancang sebuah media promosi dan penjualan online berbasis website e- commerce penjualan tenun ikat. Perancangan dan pembuatan ini dimaksudkan untuk memudahkan penjualan dan promosi, juga mempermudah konsumen memilih model-model tenun ikat Nusa Tenggara Timur, tanpa harus datang ke toko secara langsung, terlebih lagi dimasa pandemic covid-19. Dalam proses pembangunan website E-Commerce ini menggunakan bahasa Pemograman Php dan Mysql serta, teknik yang digunakan yaitu waterfall. Metode aliran data yang digunakan adalah metode tersetruktur yang terdiri dari Data Flow Diagram (DFD) dalam menggambarkan model fungsional dan Entity Relationship Diagram (ERD) untuk menggambarkan model data serta, teknik pengujianya menggunakan Blackbox testing. Tujuan yang ingin dicapai dari pembangunan Web E-Commerce ini adalah Agar mempermudah pembeli untuk melakukan transaksi dimanapun pembeli berada tanpa harus datang langsung ke Toko Fanny Art Shop
Hilbert schemes of nonreduced divisors in Calabi-Yau threefolds and W-algebras
A W-algebra action is constructed on the equivariant Borel-Moore homology of
the Hilbert scheme of points on a nonreduced plane in three dimensional affine
space, identifying it to the vacuum W-module. This is based on a generalization
of the ADHM construction as well as the W-action on the equivariant Borel-Moore
homology of the moduli space of instantons constructed by Schiffmann and
Vasserot.Comment: 41 page
Non-magnetic left-handed material
We develop a new approach to build a material with negative refraction index.
In contrast to conventional designs which make use of a resonant behavior to
achieve a non-zero magnetic response, our material is intrinsically
non-magnetic and relies on an anisotropic dielectric constant to provide a
left-handed response in waveguide geometry. We demonstrate that the proposed
material can support surface (polariton) waves, and show the connection between
polaritons and the enhancement of evanescent fields, also referred to as
super-lensing
Analysis of Clumps in Molecular Cloud Models: Mass Spectrum, Shapes, Alignment and Rotation
Observations reveal concentrations of molecular line emission on the sky,
called ``clumps,'' in dense, star-forming molecular clouds. These clumps are
believed to be the eventual sites of star formation. We study the
three-dimensional analogs of clumps using a set of self-consistent,
time-dependent numerical models of molecular clouds. The models follow the
decay of initially supersonic turbulence in an isothermal, self-gravitating,
magnetized fluid. We find the following. (1) Clumps are intrinsically triaxial.
This explains the observed deficit of clumps with a projected axis ratio near
unity, and the apparent prolateness of clumps. (2) Simulated clump axes are not
strongly aligned with the mean magnetic field within clumps, nor with the
large-scale mean fields. This is in agreement with observations. (3) The clump
mass spectrum has a high-mass slope that is consistent with the Salpeter value.
There is a low-mass break in the slope at \sim 0.5 \msun, although this may
depend on model parameters including numerical resolution. (4) The typical
specific spin angular momentum of clumps is . This is larger than the median specific angular momentum of binary
stars. Scaling arguments suggest that higher resolution simulations may soon be
able to resolve the scales at which the angular momentum of binary stars is
determined.Comment: 14 pages, 13 figures, to appear in 2003 July 20 Ap
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