Cutting load capacity of end mills with complex geometry

Cutting load capacity of cemented carbide end mills with high length-to-diameter ratios is determined from critical geometric and loading parameters, including a stress concentration factor (SCF) to account for serrated edges, which is determined by finite element analysis. Tensile strengths are characterised using a statistical Weibull analysis from 4-point bend tests of cemented carbide blanks of two different diameters. The approach is used to predict probability of survival for cutters under different loading conditions. Results are compared to measured failure cutting loads under service conditions as well as to those measured in static three point bend tests

Mean-Field Approximation to the Master Equation for Sympathetic Cooling of Trapped Bosons

We use the mean-field approximation to simplify the master equation for sympathetic cooling of Bosons. For the mean single-particle occupation numbers, this approach yields the same equations as the factorization assumption introduced in an erlier paper. The stationary or equilibrium solution of the resulting master equation for the one-body density matrix shows that the mean-field approximation breaks down whenever the fraction of condensate Bosons exceeds ten percent or so of the total. Using group-theoretical methods, we also solve the time-dependent master equation for the one-body density matrix. Given the time dependence of the mean single-particle occupation numbers, this solution is obtained by quadratures. It tends asymptotically towards the equilibrium solution.Comment: submitted to PR

Conductivity of Coulomb interacting massless Dirac particles in graphene: Regularization-dependent parameters and symmetry constraints

We compute the Coulomb correction $\mathcal{C}$ to the a. c. conductivity of interacting massless Dirac particles in graphene in the collisionless limit using the polarization tensor approach in a regularization independent framework. Arbitrary parameters stemming from differences between logarithmically divergent integrals are fixed on physical grounds exploiting only spatial $O(2)$ rotational invariance of the model which amounts to transversality of the polarization tensor. Consequently $\mathcal{C}$ is unequivocally determined to be $(19- 6\pi)/12$ within this effective model. We compare our result with explicit regularizations and discuss the origin of others results for $\mathcal{C}$ found in the literature

Factors Influencing Consumer Bidding Behavior in Online Auction (Consumer-to-Consumer)

According to the critical analysis of theoretical and empirical literature, there is a need to better understand and to examine the relationship between consumer bidding behavior in online auctions and the related influencing factors. Online auction is a relatively new field of study. It is important to further research the area of online auctions. The theoretical structure, research questions, research hypotheses, and the hypothesized research model are introduced. Theory of Reasoned Auction, Theory of Planned Behavior, and Technology Acceptance Model are used as theoretical foundations of this study. This study focuses on the relationship between consumer bidding behaviors in online auctions, and factors influencing those behaviors. The research is focused on the following influencing factors: customer satisfaction, ease of use of the web site, and demographic profile. A non-experimental, quantitative, correlational research design was conducted to study the relationship between influencing factors and consumer bidding behavior. The target population was people with online shopping experience with eBay who have current access to the Internet. After IRB approval, the researcher collected the date by a paper and pen questionnaire at a public beach in Boca Raton. The questionnaire was handed out to the eligible participants. The questionnaires were dropped in a closed box. The data for this study collected from at least 146 eligible participants using pen and paper questionnaire as an instrument. Findings helped to serve the online consumers and the vendors, as well as being a scholarly contribution to the study of online bidding. This study used SPSS software to analyze the collected data. Descriptive statistics, Cronbach alpha, Pearson r correlation, simple regression, and multiple regressions, were applied in this study. The study findings indicated that an individual\u27s bidding behavior is influenced positively by factors like consumer satisfaction and ease of use and bidding behavior is not influenced by demographic characteristics

Parametric Competition in non-autonomous Hamiltonian Systems

In this work we use the formalism of chord functions (\emph{i.e.} characteristic functions) to analytically solve quadratic non-autonomous Hamiltonians coupled to a reservoir composed by an infinity set of oscillators, with Gaussian initial state. We analytically obtain a solution for the characteristic function under dissipation, and therefore for the determinant of the covariance matrix and the von Neumann entropy, where the latter is the physical quantity of interest. We study in details two examples that are known to show dynamical squeezing and instability effects: the inverted harmonic oscillator and an oscillator with time dependent frequency. We show that it will appear in both cases a clear competition between instability and dissipation. If the dissipation is small when compared to the instability, the squeezing generation is dominant and one can see an increasing in the von Neumann entropy. When the dissipation is large enough, the dynamical squeezing generation in one of the quadratures is retained, thence the growth in the von Neumann entropy is contained

Protecting, Enhancing and Reviving Entanglement

We propose a strategies not only to protect but also to enhance and revive the entanglement in a double Jaynes-Cummings model. We show that such surprising features arises when Zeno-like measurements are performed during the dynamical process

Stern-Gerlach Entanglement in Spinor Bose-Einstein Condensates

Entanglement of spin and position variables produced by spatially inhomogeneous magnetic fields of Stern-Gerlach type acting on spinor Bose-Einstein condensates may lead to interference effects at the level of one-boson densities. A model is worked out for these effects which is amenable to analytical calculation for gaussian shaped condensates. The resulting interference effects are sensitive to the spin polarization properties of the condensate.Comment: 9 pages, 2 figure