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911.
S. M. Arnold A. F. Saleeb H. Q. Tan Y. Zang 《International journal for numerical methods in engineering》1994,37(11):1931-1944
The issue of developing effective and robust schemes to implement a class of the Ogden-type hyperelastic constitutive models is addressed. To this end, special purpose functions (running under MACSYMA) are developed for the symbolic derivation, evaluation, and automatic FORTRAN code generation of explicit expressions for the corresponding stress function and material tangent stiffness tensors. These explicit forms are valid over the entire deformation range, since the singularities resulting from repeated principal-stretch values have been theorectically removed. The required computational algorithms are outlined, and the resulting FORTRAN computer code is presented. 相似文献
912.
We derive an effective single-band Hubbard type Hamiltonian for CuO2 planes. The Hamiltonian includes both electron-electron repulsion and electron-phonon coupling to oxygen vibrational modes. We start with first-principles density functional theory parameters and then map onto a single-band model. Unlike previous mappings to a single-band Hamiltonian, ours explicitly preserves the Fermi surface shape and matrix elements of the many-band Hamiltonian. We consider both in-plane oxygen breathing modes as well as out-of-plane tilting modes. The latter modes have a quadratic electron-phonon coupling, and are also highly anharmonic in La2CuO4 based superconductors. The coupling to breathing modes is too small to account for highT
c, while the coupling to quadratic modes is much stronger even though they would be neglected in a standard Migdal-Eliashberg approach to superconductivity. 相似文献
913.
Highlights key considerations that should be addressed by consulting psychologists to demonstrate the value of assessment services that they provide to clients. Executive and managerial assessment (EMA) is done in a variety of contexts, at multiple levels, and for multiple purposes. In order to demonstrate the value of EMA, it is suggested that consultants present a 2-part framework of evidence to decision makers. First, they should present the results of utility analysis, using the very best parameter estimates available. Second, they should present a detailed linkage of essential job tasks to required knowledge, skills, abilities, and other characteristics (KSAOs). Then, KSAOs should be linked to instruments of prediction back to essential job tasks. Value is therefore demonstrated in 2 ways: in financial terms as well as by presenting construct-oriented evidence of validity. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
914.
915.
Centralized and distributed automated guided vehicle system (AGVS) models for materials handling, and the model for part processing are integrated into a single coherent model. This formulation can be used to collectively schedule and control the entire flexible manufacturing system (FMS) as opposed to the traditional separate scheduling of part processing and material handling. The two AGVS models are based on Petri nets and can be directly used in the scheduling method that uses Petri nets for formulation and heuristic search for solution. This method employs a global search to seek the optimal operation of an entire FMS. Scheduling examples are presented and the method compares favorably with the results simulated using heuristic dispatch rules 相似文献
916.
Wang F.-Y. Gildea K. Jungnitz H. Chen D.D. 《Industrial Electronics, IEEE Transactions on》1994,41(6):641-653
The manufacturing message specification (MMS) is the ISO standard communication protocol specific to manufacturing. To analyze MMS design and performance, service unit automats are introduced to represent individual MMS services, while service connection Petri Nets (PNs) are constructed from these automats to describe MMS service connections and processes. This approach makes MMS protocol specification and analysis possible in terms of well-developed concepts and methods in PN theory. It leads to a distributed and hierarchical model of MMS software system by integrating service connection PNs. A generalized stochastic PN for MMS performance evaluation is obtained by incorporating service parameters and time factors into the model. A technique based on T-invariants is used to simplify the performance analysis 相似文献
917.
Enhanced performance is demonstrated in n-type metal-oxide-semiconductor field-effect transistors with channel regions formed by pseudomorphic growth of strained Si on relaxed Si1-xGex. Standard MOS fabrication techniques were utilized, including thermal oxidation of the strained Si. Surface channel devices show low-field mobility enhancements of 80% at room temperature and 12% at 10 K, when compared to control devices fabricated in Czochralski Si. Similar enhancements are observed in the device transconductance. In addition, buried channel devices show peak room temperature mobilities about three times that of control devices 相似文献
918.
Shye Lin Wu Chung Len Lee Tan Fu Lei Chen C.F. Chen L.J. Ho K.Z. Ling Y.C. 《Electron Device Letters, IEEE》1994,15(4):120-122
In this study, it is demonstrated that the incorporation of fluorine can enhance poly-Si/Si interfacial oxide break-up in the poly-Si emitter contacted p+-n shallow junction formation. The annealing temperature for breaking up the poly-Si/Si interfacial oxide has been found to be as low as 900°C. As a result, the junction depth of the BF2-implanted device is much larger than that of the boron-implanted device 相似文献
919.
Zolper J.C. Shenvin M.E. Baca A.G. Shul R.J. Klem J.F. Hietala V.M. 《Electron Device Letters, IEEE》1994,15(12):493-495
C ion implantation has been employed, for the first time, to form the buried p-layer in GaAs, self-aligned, ion implanted JFETs. Comparable DC performance was seen for JFETs with C or Mg implants; however, C-backside JFETs showed superior high-frequency performance. High dose C-backside devices had a ft of 28.3 GHz and a fmax of 43.2 GHz for a 0.5 μm gate length that were 28% and 46% higher, respectively, than comparable Mg-implanted JFETs. This enhancement is a result of the lower Cgs in the C-backside device resulting from he inherently low activation of the implanted C below the channel while the C still effectively compensated the tail of the Si-channel implant. This approach relaxes the trade-off between optimizing the DC and the AC performance for the buried p-implant in GaAs JFETs and MESFET's 相似文献
920.
Responds to M. F. Hoyt's (see record 1995-22250-001) commentary on T. F. Van Denburg and E. J. Van Denburg's (see record 1994-18427-001) response to Hoyt's (see record 1994-18395-001) commentary on Van Denburg and Van Denburg's (see record 1993-06526-001) article about a case of premature therapy termination. Issues related to limits and flexibility in treatment are addressed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献