Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 2882-2885 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present preliminary results of a study of defects in GaAs-AlGaAs superlattices using deep-level transient spectroscopy (DLTS). A dramatic difference is observed between the DLTS spectra of two superlattices when the superlattice period is doubled. This is explained by the presence of miniband conduction in the case of the smaller period and its absence in the case of the larger, and by the consequent difference in the distribution of electrons in the superlattice. Observed activation energies must be reinterpreted for comparisons to bulk material.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 2121-2123 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The thin strained superlattice (TSSL) concept is introduced as a means for extending the practical range of application for pseudomorphic Inx Ga1−x As on GaAs. Growth and characterization results are presented for pseudomorphic high electron mobility transistor structures with GaAs-In0.3 Ga0.7 As TSSL active layers grown by molecular beam epitaxy. The TSSLs are composed of three periods of GaAs(15 A(ring))- In0.3 Ga0.7 As(h2 ), where h2 ranges from 30 to 52 A(ring). Modulation doping of the TSSLs is provided by atomic planar-doped Al0.3 Ga0.7 As overlayers with 45 A(ring) undoped spacers. 77 K Hall effect and transmission electron microscopy reveal that relatively thick TSSLs can be grown with high electronic and structural quality, comparable to much thinner In0.3 Ga0.7 As single quantum wells. Results are compared with a model for critical layer thickness and discussed in light of in situ reflection high-energy electron diffraction measurements.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1432-1262
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of this study was to assess (a) the incidence of perineal descent and (b) the relationship between radiological abnormalities of the pelvic floor and rectoanal manometric disturbances in patients consulting for constipation. Lateral radiographs in both the left lateral and supine positions studied pelvic floor descent. Results obtained in the 25 patients (mean age 47 years) studied were compared with those of 12 controls (mean age 58 years). Pelvic floor descent, never seen in controls, was demonstrated in 14 patients who were older (53±3 years, mean ±SD) than the 11 with a normal radiological examination (38±3 years,p〈0.05). Anal low pressures (3 cases) and a low amplitude of rectoanal inhibitory reflex (RAIR) (5 cases) were shown only in patients with perineal descent and anal high pressures only in those with normal radiology. Our results suggest that (a) perineal descent is a common finding in over 50% of constipated patients and (b) anorectal motility is related to pelvic floor function.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    BT technology journal 17 (1999), S. 9-12 
    ISSN: 1573-1995
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Springer
    BT technology journal 17 (1999), S. 60-68 
    ISSN: 1573-1995
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract It is an unfortunate fact that current general-purpose middleware implementations cannot support large-scale, wide-area, real-time, high-throughput applications using distributed objects. This paper discusses the background to middleware and explores the need for research into techniques that support high-capacity implementations In order to place the role of this work in context, an overview is given of the simple applications-middleware-infrastructure three-layered model that has been adopted. The paper also gives some background on how applications may specify the non-functional characteristics that they demand of supporting middleware, including invocation latency, which is a widely recognised, measured and reported metric, and invocation throughput rate, which is not. The paper establishes that there is a growing demand for high-invocation-throughput applications, such as the World Wide Web (WWW), collaborative virtual reality (CVR) and intelligent networks (INs), and also that there is increasing availability of suitable high-capacity infrastructure including networks, hosts and operating systems. It also examines the reasons for a lack of implemented high-capacity capacity middleware and reviews current directions in distributed object (DO) research. There is insufficient but growing activity in high-throughput techniques, such as weak-consistency approaches to object replication, that would enable applications to take advantage of high-capacity infrastructure.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 39 (1996), S. 687-704 
    ISSN: 0029-5981
    Keywords: boundary element methods ; Cauchy principal-value integrals ; Hadamard finite-part integrals ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Hypersingular integrals are guaranteed to exist at a point x only if the density function f in the integrand satisfies certain conditions in a neighbourhood of x. It is well known that a sufficient condition is that f has a Hölder-continuous first derivative. This is a stringent condition, especially when it is incorporated into boundary-element methods for solving hypersingular integral equations. This paper is concerned with finding weaker conditions for the existence of one-dimensional Hadamard finite-part integrals: it is shown that it is sufficient for the even part of f (with respect to x) to have a Hölder-continuous first derivative - the odd part is allowed to be discontinuous. A similar condition is obtained for Cauchy principal-value integrals. These simple results have non-trivial consequences. They are applied to the calculation of the tangential derivative of a single-layer potential and to the normal derivative of a double-layer potential. Particular attention is paid to discontinuous densities and to discontinuous boundary conditions. Also, despite the weaker sufficient conditions, it is reaffirmed that, for hypersingular integral equations, collocation at a point x at the junction between two standard conforming boundary elements is not permissible, theoretically. Various modifications to the definition of finite-part integral are explored.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 38 (1995), S. 3483-3495 
    ISSN: 0029-5981
    Keywords: discretized Green's functions ; multiple scattering ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Discretization of boundary integral equations leads to large full systems of algebraic equations, in practice. Partitioning is a method for solving such systems by breaking them down into smaller systems. It may be viewed merely as a technique from linear algebra. However, it is profitable to view it as arising directly from partitions of the boundary; these partitions could be natural (such as two separate boundaries) but they need not be. We investigate partitioning in the context of multiple scattering of acoustic waves by two sound-hard obstacles (the ideas extend to other physical situations). Specifically, we make a connection between partitioning and the use of the exact Green's function for a single obstacle in isolation. This suggests computing the action of this Green's function once-and-for-all, storing it (perhaps on a compact disc), and then using it to solve other problems in which the second obstacle is altered. One example of this approach is computing the stress distribution around a cavity of a standard-but-complicated shape inside a structure whose shape is varied. The theoretical foundation for these ideas is given, as well as a connection with the use of generalized Born series for multiple-scattering problems. Important distinctions between the partitioning/Green's function idea in this paper and seemingly similar ideas such as substructuring, multi-zoning, and domain decomposition are made.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 42 (1998), S. 885-906 
    ISSN: 0029-5981
    Keywords: boundary elements ; Cauchy principal-value integrals ; Hadamard finite part integrals ; Hölder continuity ; relaxed regularization ; Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Three stages are involved in the formulation of a typical direct boundary element method: derivation of an integral representation; taking a Limit To the Boundary (LTB) so as to obtain an integral equation; and discretization. We examine the second and third stages, focussing on strategies that are intended to permit the relaxation of standard smoothness assumptions. Two such strategies are indicated. The first is the introduction of various apparent or ‘pseudo-LTBs’. The second is ‘relaxed regularization’, in which a regularized integral equation, derived rigorously under certain smoothness assumptions, is used when less smoothness is available. Both strategies are shown to be based on inconsistent reasoning. Nevertheless, reasons are offered for having some confidence in numerical results obtained with certain strategies. Our work is done in two physical contexts, namely two-dimensional potential theory (using functions of a complex variable) and three-dimensional elastostatics. © 1998 John Wiley & Sons, Ltd.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...