34,127 research outputs found
Recommended from our members
Modelling and simulation on the tool wear in nanometric cutting
Tool wear is a significant factor affecting the machined surface quality. In this paper, a Molecular Dynamics (MD) simulation approach is proposed to model the wear of the diamond tool in nanometric cutting. It includes the effects of the cutting heat on the workpiece property. MD simulation is carried out to simulate the nanometric cutting of a single crystal silicon plate with the diamond tip of an Atomic Force Microscope (AFM). The wear mechanism is investigated by the calculation of the temperature, the stress in the diamond tip, and the analysis of the relationship between the temperature and sublimation energy of the diamond atoms and silicon atoms. Microstrength is used to characterize the wear resistance of the diamond tool. The machining trials on an AFM are performed to validate the results of the MD simulation. The results of MD simulation and AFM experiments all show that the thermo-chemical wear is the basic wear mechanism of the diamond cutting tool
Thermodynamical quantities of lattice full QCD from an efficient method
I extend to QCD an efficient method for lattice gauge theory with dynamical
fermions. Once the eigenvalues of the Dirac operator and the density of states
of pure gluonic configurations at a set of plaquette energies (proportional to
the gauge action) are computed, thermodynamical quantities deriving from the
partition function can be obtained for arbitrary flavor number, quark masses
and wide range of coupling constants, without additional computational cost.
Results for the chiral condensate and gauge action are presented on the
lattice at flavor number , 1, 2, 3, 4 and many quark masses and coupling
constants. New results in the chiral limit for the gauge action and its
correlation with the chiral condensate, which are useful for analyzing the QCD
chiral phase structure, are also provided.Comment: Latex, 11 figures, version accepted for publicatio
Knowledge-based acquisition of tradeoff preferences of negotiating agents
A wide range of algorithms have been developed for various types of automated egotiation. In developing such algorithms the main focus has been on their efficiency and their effectiveness. However, this is only part of the picture. Agents typically negotiate on behalf of their owners and for this to be effective the agent must be able to adequately represent the owners' preferences. However, the process by which such knowledge is acquired is typically left unspecified. To remove this shortcoming, we present a case study indicating how the knowledge for a particular negotiation algorithm can be acquired. More precisely, according to the analysis on the automated negotiation model, we identified that user trade-off preferences play a fundamental role in negotiation in general. This topic has been addressed little in the research area of user preference elicitation for general decision making problems as well. In a previous paper, we proposed an exhaustive method to acquire user trade-off preferences. In this paper, we developed another method to remove the limitation of the high user workload of the exhaustive method. Although we cannot say that it can exactly capture user trade-off preferences, it models the main commonalities of trade-off relations and re users' individualities as well
Bound States and Critical Behavior of the Yukawa Potential
We investigate the bound states of the Yukawa potential , using different algorithms: solving the Schr\"odinger
equation numerically and our Monte Carlo Hamiltonian approach. There is a
critical , above which no bound state exists. We study the
relation between and for various angular momentum quantum
number , and find in atomic units, , with , ,
, and .Comment: 15 pages, 12 figures, 5 tables. Version to appear in Sciences in
China
Recommended from our members
An investigation on the mechanics of nanometric cutting and the development of its test-bed
The mechanics of machining at a very small depth of cut (100 nm or less) is not
well understood. The chip formation physics, cutting forces generation, resulting
temperatures and the size effects significantly affect the efficiency of the process
and the surface quality of the workpiece. In this paper, the cutting mechanics
at nanometric scale are investigated in comparison with conventional cutting
principles. Molecular Dynamics (MD) is used to model and simulate the nanometric
cutting processes. The models and simulated results are evaluated and
validated by the cutting trials on an atomic force microscope (AFM).
Furthermore, the conceptual design of a bench-type ultraprecision machine tool
is presented and the machine aims to be a facility for nanometric cutting of threedimensional
MEMS devices. The paper concludes with a discussion on the potential
and applications of nanometric cutting techniques/equipment for the
predictabilty, producibility and productivity of manufacturing at the nanoscale
An investigation on the mechanics of nanometric cutting and the development of its test-bed
The mechanics of machining at a very small depth of cut (100 nm or less) is not
well understood. The chip formation physics, cutting forces generation, resulting
temperatures and the size effects significantly affect the efficiency of the process
and the surface quality of the workpiece. In this paper, the cutting mechanics
at nanometric scale are investigated in comparison with conventional cutting
principles. Molecular Dynamics (MD) is used to model and simulate the nanometric
cutting processes. The models and simulated results are evaluated and
validated by the cutting trials on an atomic force microscope (AFM).
Furthermore, the conceptual design of a bench-type ultraprecision machine tool
is presented and the machine aims to be a facility for nanometric cutting of threedimensional
MEMS devices. The paper concludes with a discussion on the potential
and applications of nanometric cutting techniques/equipment for the
predictabilty, producibility and productivity of manufacturing at the nanoscale
Improved lattice QCD with quarks: the 2 dimensional case
QCD in two dimensions is investigated using the improved fermionic lattice
Hamiltonian proposed by Luo, Chen, Xu, and Jiang. We show that the improved
theory leads to a significant reduction of the finite lattice spacing errors.
The quark condensate and the mass of lightest quark and anti-quark bound state
in the strong coupling phase (different from t'Hooft phase) are computed. We
find agreement between our results and the analytical ones in the continuum.Comment: LaTeX file (including text + 10 figures
- …