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Considering the present limitation of the need for external parameters to describe the nucleus–nucleus potential and the couplings in the coupled-channels calculations, this work introduces an improved method without adjustable parameter to overcome the limitation and then sort out the positive Q-value neutron transfers (PQNT) effects based on the CCFULL calculations. The corresponding analysis for Ca + Ca , S , Ca + Sn , and S , Ca + Zr provides a reliable proof and a quantitative evaluation for the residual enhancement (RE) related to PQNT. In addition, the RE for S 32 , Ca 40 + Zr 94 shows an unexpected larger enhancement than S 32 , Ca 40 + Zr 96 despite the similar multi-neutron transfer Q-values. This method should rather strictly test the fusion models and be helpful for excavating the underlying physics.

The quasielastic scattering excitation functions for 16 O + 152 Sm,170 Er and 174 Yb were measured with high precision at a backward angle with small energy intervals at energies near the Coulomb barriers. The hexadecapole deformation (β 4 ) of the target nuclei was extracted by using the lower-energy data and the obtained values agree with the available results reasonably well. This offers a sensitive method to extract β 4 . This method is especially meaningful for the radioactive nuclei considering the low beam intensities.

This contribution reports the recent experimental studies for the coupling effect of the positive Q-value neutron transfer (PQNT) channels on near-barrier fusion with heavy-ions, measured by an electrostatic deflector setup. This effect is expected to be important in some situations. In this presentation, the experimental studies for the nearbarrier fusion of 32 S +90,94,96 Zr,16 O +76 Ge,18 O +74 Ge, and16,18 O +58 Ni are reported. Also a method, based on the CCFULL calculations with suitable inelastic couplings, to sort out the PQNT effect is presented.

A series of experiments have been performed by complete kinematics measurements to study two-proton (2 p) correlated emission from the excited states of 17,18Ne and 28,29S via the Coulomb excitation by bombarding on 197Au target. 2p and residua coincident events were picked out under strict conditions. Visible p − p correlations were observed. It is shown that 2p can be emitted from the high-lying excited states. 2p halo may lead to 2p emission with large spectroscopy factor for the states close to or beyond the threshold.

Using the method of elastic scattering between a light nucleus and a heavy nucleus at energies below the Coulomb barrier, we try to precisely and systematically determine the electric polarizabilities of 3He and 4He. The precision of R(E) (see Eq. (1)) in our experiment is about 0.1% and thus this experiment is very challenging. In order to reach this precision, some studies about systematic uncertainties are conducted, such as a comparison between the methods for extracting the polarizabilities and a calculation about systematic uncertainties due to the misalignment of beam and detector systems. Our results show that the systematic uncertainties are all much less than 0.1% and are therefore negligible. Detailed data analysis is still in progress.

The electrochemical corrosion behaviour of Ti and Pd ion implanted pure iron specimens in 0.5 mol l−1 sodium acetate/acetic acid (NaAc/HA) aqueous or buffer solution with pH 5.0, respectively, has been studied. The ion implantations were performed by using a MEWA source ion implantor. The changes in composition and valency states of elements in the near surface layers of implanted specimens compared with the control were analyzed by Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). The changes in electrochemical corrosion behaviour of implanted iron demonstrated that: (1) Ti ion implantation induced nobler corrosion potential, depressed corrosion current and enhanced polarization resistance; (2) Pd ion, implantation decreased the critical passitive current of iron and maintained a better passivity in acetate buffer solution with pH 5.0 and (3) the active corrosion rate of Pd implanted iron was even higher than that of unimplanted specimens when oxide films had been damaged.

The 13 C( 9 Be, 8 Li) 14 N angular distribution was measured with a 9 Be beam of 40 MeV. The proton spectroscopic factor of the 9 Be ground state was extracted to be 0.73 ± 0.15 by the normalization of the calculated differential cross sections with the distorted-wave Born approximation (DWBA) to the experimental data. The spectroscopic factor was compared to existing theoretical and experimental values

The Beijing Spectrometer (BES) is a general purpose solenoidal detector at the Beijing Electron Positron Collider (BEPC). It is designed to study exclusive final states in e + e − annihilations at the center of mass energy from 3.0 to 5.6 GeV. This requires large solid angle coverage combined with good charged particle momentum resolution, good particle identification and high photon detection efficiency at low energies. In this paper we describe the construction and the performance of BES detector.

In this paper, an approach for modelling and analysis of massively multiplayer online games (MMOGs) is proposed. By using our models, based on Markov process and queuing theory, we can investigate the impact of various factors, such as game types, the number of players, the intensity of players or NCPs interaction, the number of regions in a game world, avatar region-transition rate, and network configuration, on the system performance. A number of resource-cost functions are defined, which map the system resource consumed to the cost during a game play. We choose the federated peer-to-peer architecture as a target for this study, since it is a typical and potential architecture proposed recently and attracting more attention.

The existing session establishment scenario of IP multimedia subsystem (IMS) suffers from triangular routing for a certain period of time when an end SIP user or terminal is mobile. In this paper, the performance of three possible session establishment scenarios in a mobile environment is investigated by using an analytical model. The model is developed based on the expressions of cost functions, which may represent system delay and overhead involved in sessions establishment. Some numerical results are demonstrated which provides useful insights into the system behavior. Finally, a decision algorithm is demonstrated in this article to select the optimal session set up option

Cellular IP requires that a mobile host be using exactly one gateway to the Internet backbone with mobile IP at a time. When multiple gateways are used in a cellular IP network, the optimal design for the multiple domains is needed. In this paper an analytical model is presented for the performance analysis of a cellular IPv6 network with multiple gateways. Based on this model, an optimal system design can be theoretically found in terms of the network size, traffic load, user population, user mobility and routing algorithm for IP packets in a domain. Consequently, an algorithm is proposed for breaking a large cellular IP domain into two small domains, which can be easily used for the system selection in practice. Finally, some numerical results are demonstrated for a number of typical cases presented in the algorithm.

A computer game is usually considered as a finite state machine. For a distributed multiplayer game, state information has to be exchanged among its players when they move and interact in a virtual space. If the number of players is very large, only a small subset of the game entities, controlled by their players, is interested and forms a multicast group so as to reduce the information dissemination over the network. In this paper, analytical models are proposed for evaluating the performance of multicast groups with multiplayer games in peer-to-peer networks. The system modeling is based on two stochastic processes and their possible solutions in terms of game type, player activity, and entity vision size, mode of user input processing, and grouping strategy. The cost of game operations on consumed resources is introduced to characterize the performance measure. Numerical examples are demonstrated, which provide useful insights of the behaviors of such systems.

In this paper an analytical model is presented in order to provide useful insight into the performance behaviour of mobile IPv6 in the context of a binding lifetime setting. By using this model, the optimal binding lifetime can be estimated in terms of a user mobility, traffic workload, and network structure. An algorithm for dynamically setting the binding lifetime in mobile IPv6 networks is proposed based on the analytical model. The numerical results of the system simulation are also demonstrated.

This paper presents a congestion avoidance algorithm for interconnected metropolitan area networks in the context of the FASTPAC network in Australia. A concept called congestion hazard is proposed. Congestion prediction is based on periodically computing a Congestion Hazard Event Matrix in each router. The interaction between congestion control and routing algorithm has been taken into account in the algorithm. Congestion avoidance is achieved through the strategy of re-routing, temporary cessation of sending, and dropping packets at the routers. Simulation shows its feasibility and effectiveness.

An analytic model is presented for the performance evaluation of rate based flow controls for the transport layer in high speed networks by using Markov chains. In order to provide insights into the behavior of the rate control mechanisms, critical parameters, such as round-trip delay, processing capacity, receiver buffer size, and traffic characteristics, are considered in the model. The performance measures are mainly concerned with the loss probability, throughput and average overload time. A simple optimal approach to the design of the rate control systems is also proposed. >

In this paper we deal with the design and analysis of a typical multimedia server, video-on-demand server (VoD). If we define the performance measure of the VoD server as the maximum number of concurrent access processes it can support, the system performance depends on a number of the system characteristics. They are: (i) storage devices contention; (ii) resource allocation, such as buffer size; (iii) QoS control. Thus, in order to achieve the best performance of a server the design trade-off among theses factors should be investigated quantitatively. In this paper we formulate and solve a problem of allocating resources for such a multimedia server in order to maximize concurrent video accesses under QoS guarantees. The solution is theoretically based on economic models and queuing theory. By using our optimization procedure we may estimate the maximum number of concurrent video accesses with optimal buffer allocation and QoS guarantees.

A dynamic sessions control algorithm for multimedia distributed systems is presented in this paper. The algorithm is theoretically based on a "demand and supply" economic model and specifically on "Pareto efficient allocation". In this mechanism, users compete for resources selfishly and attempt to get maximal benefit while resources are not only utilised efficiently, but also allocated in a such way that users with diverse Quality of Services (QoS) requirements achieve individual optimality. The algorithm includes a session renegotiation function which is used to reduce the blocking probability of calls significantly. Finally, the simulation results of the algorithm are demonstrated and discussed.

This paper presents a fictitious boundary condition (FBC) and yields an iterative domain decomposition method (DDM) algorithm for analyzing waveguide problems effectively. Further, a relaxed iterative algorithm is introduced to improve the iterative convergence. To give the explanation of the method, a model of a rectangular waveguide with E-plane discontinuity is established. For simplicity, the reflection coefficient and transmission coefficient of the primary mode in the waveguide are chosen as a numerical calculated example to verify this method.

An analytical queueing model is proposed based on our study of the code distribution and especially in the integrated or in-band code distribution systems with active networks. By using this model the system performance and reliability can be evaluated so as to provide insights into their behaviour. Since there are different proposals for the code distribution reported recently, it is significant to provide a technique to find an optimal decision in the network design. A procedure to help with this decision is presented. Some numerical results of using our performance model and decision procedure are also demonstrated.

The role of neutron transfers is investigated in the fusion process below the Coulomb barrier by analyzing 32S+90Zr and 32S+96Zr as benchmark reactions. A full coupled-channel calculation of the fusion excitation functions has been performed for both systems by using multi-neutron transfer coupling for the more neutron-rich reaction. The enhancement of fusion cross sections for 32S+96Zr is well reproduced at sub-barrier energies by NTFus code calculations including the coupling of the neutron-transfer channels following the Zagrebaev semiclassical model. We found similar effects for 40Ca+90Zr and 40Ca+96Zr fusion excitation functions., Comment: Minor corrections, 11 pages, 4 figures, Fusion11 Conference, Saint Malo, France, 2-6 mai 2011

A contrastive research on two-proton (2p) emissions from excited states of the even-Z nucleus 28S and its one-proton daughter, the odd-Z nucleus 27P was performed by complete-kinematics measurements. The opening angles as well as relative momenta between two emitted protons and invariant masses of decaying systems were reconstructed through the event-by-event analysis of heavy fragments coincident with two protons. With the help of Monte Carlo simulations, results show a diproton-type decay with the branching ratio of 20 − 7 + 6 % for 28S while mainly three-body simultaneous decay in the phase space and/or 2p sequential emission for 27P. Present results show that the diproton correlations may result from the proton configuration in the initial state like 2p skin/halo structure rather than the deformed orbit.