Isotopic replacement in ionic systems: the 4He2+ + 3He -> 3He4He+ + 4He reaction

Full quantum dynamics calculations have been carried out for the ionic reaction 4He2+ + 3He and state-to-state reactive probabilities have been obtained using both a time-dependent (TD) and a time-independent (TI) approach. An accurate ab-initio potential energy surface has been employed for the present quantum dynamics and the two sets of results are shown to be in agreement with each other. The results for zero total angular momentum suggest a marked presence of atom exchange (isotopic replacement) reaction with probabilities as high as 60%. The reaction probabilities are only weakly dependent on the initial vibrational state of the reactants while they are slightly more sensitive to the degree of rotational excitation. A brief discussion of the results for selected higher total angular momentum values is also presented, while the l-shifting approximation [1] has been used to provide estimates of the total reaction rates for the title process. Such rates are found to be large enough to possibly become experimentally accessible

A Space Vector PWM With Common-Mode Voltage Elimination for Open-End Winding Five-Phase Drives With a Single DC Supply

Open-end winding three-phase drive topologies have been extensively investigated in the last two decades. In the majority of cases supply of the inverters at the two sides of the winding is provided from isolated dc sources. Recently, studies related to multiphase open-end winding drives have also been conducted, using isolated dc sources at the two winding sides. This paper investigates for the first time a five-phase open-end winding configuration, which is obtained by connecting a two-level five-phase inverter at each side of the stator winding, with both inverters supplied from a common dc source. In such a configuration it is essential to eliminate the common-mode voltage (CMV) that is inevitably created by usual PWM techniques. Based on the vector space decomposition (VSD), the switching states that create zero CMV are indentified and plotted. A space vector pattern with large redundancy of switching states is obtained. Suitable space vectors are then selected to realize the required voltage reference at the machine terminals with zero CMV. The large number of redundant states enables some freedom in the choice of switching states to impress these space vectors. Out of numerous possibilities, two particular switching sequences are chosen for further investigation. Both are implemented in an experimental setup, and the results are presented and discussed. © 2013 IEEE

Integration of Six-Phase EV Drivetrains into Battery Charging Process with Direct Grid Connection

The paper proposes two novel topologies for integrated battery charging of electric vehicles (EVs). The integration is functional and manifests through re-utilization of existing propulsion drivetrain components, primarily a six-phase inverter and a six-phase machine, to serve as components of a fast (three-phase) charging system. An important feature of the proposed charging systems is that they are with direct grid connection, thus non-isolated from the mains. Torque is not produced in machines during the charging process. The paper provides a comprehensive evaluation of the novel systems, together with an existing topology. Various aspects of the considered chargers are detailed and elaborated, including current balancing, interleaving modulation strategy, and influence of rotor field pulsation on control and overall performance. A control strategy is proposed and the theory and control scheme are verified by experiments

An EV Drive-Train With Integrated Fast Charging Capability

This paper proposes a new class of on-board chargers for electric vehicles (EVs). Instead of being placed on-board as a separate unit, the three-phase (fast) chargers reutilize the existing components in EVs, which are already used for the propulsion. These are primarily the inverter and the machine, which however have to be multiphase (with more than three phases). The concept is valid for all multiphase propulsion drives with a prime number of phases higher than three and a single neutral point in motoring and is illustrated in detail for the five-phase inverter/five-phase machine configuration. During the charging mode, electromagnetic torque is not produced in the machine so that the rotor does not require mechanical locking. Hardware reconfiguration between propulsion and fast charging is required, but it is achieved with only two switches, which are the only two nonintegrated elements. The integrated topology is explained in this paper, together with the control scheme, and extension from five phases to higher phase numbers is illustrated using the seven-phase system as an example. Finally, the propulsion-mode operation with complete suppression of low-order harmonics, which map into the second plane, is achieved for the five-phase machine. Experimental verification of theoretical results and proposed control is provided for both charging and vehicle-to-grid mode of operation, as well as for propulsion

Magnetocentrifugal mechanism of pair creation in AGN

In the manuscript, we study the efficiency of pair creation by means of the centrifugal mechanism. The strong magnetic field and the effects of rotation, which always take place in Kerr-type black holes, guarantee the frozen-in condition, leading to the generation of an exponentially amplifying electrostatic field. This field, when reaching the Schwinger threshold, leads to efficient pair production. The process has been studied for a wide range of AGN luminosities and black hole masses, and it was found that the mechanism is very efficient, indicating that for AGNs where centrifugal effects are significant, the annihilation lines in the MeV range will be very strong.Comment: 15 pages, 5 figure

Single-Phase On-Board Integrated Battery Chargers for EVs Based on Multiphase Machines

The paper considers integration of multiphase (more than three phases) machines and converters into a single-phase charging process of electric vehicles (EVs) and, thus, complements recently introduced fast charging solutions for the studied phase numbers. One entirely novel topology, employing a five-phase machine, is introduced and assessed jointly with three other topologies that use an asymmetrical nine-phase machine, an asymmetrical six-phase machine, and a symmetrical six-phase machine. In all topologies, both charging and vehicle-to-grid (V2G) mode are viable. Moreover, all are capable of unity power factor operation. A torque is not produced in machines during charging/V2G process so that mechanical locking is not required. Hardware reconfiguration between propulsion and charging/V2G mode is either not required or minimized by using a single switch. Theoretical analysis of operating principles is given, and a control scheme, applicable to all topologies and which includes current balancing and interleaving strategy, is developed. Finally, operation of all topologies is compared by means of experiments in both charging and V2G mode, with a discussion of influence of current balancing and interleaving strategy on the overall performance

Do people have a preference for increasing or decreasing pain? An experimental comparison of psychological and economic measures in health related decision making

This paper investigates preferences for different health profiles, especially sequences of increasing and decreasing pain. We test conflicting predictions in terms of preferences over two painful sequences. The QALY concept relevant for the determination of different levels of health-related quality of life implies indifference, whereas behavioral theories find preferences related to ordering, following the peak-end-rule. Using an experimental design with real consequences we generate decisions about painful sequences induced by the cold pressor test. The results are compared with hypothetical choice data elicited using standard methods. We find that hypothetical methods reveal decisions in line with the peak-end-rule. However when it comes to real consequences of their decisions, subjects are on average not willing to pay for that preference

Determining risk preferences for pain

The QALY concept is the commonly used approach in research to evaluate the efficiency of therapies in cost utility analysis. We investigate the risk neutrality assumption for time of the QALY concept: can time be included as a linear factor? Various studies show that this assumption does not hold empirically. However, the results are based on hypothetical questionnaires rather than decisions with real consequences. Experimental economists argue that experiments are necessary to avoid hypothetical bias. Our study provides the first experimental analysis of health related decision making. Using the cold pressor test we can analyze decisions when subjects face real consequences. Analog to the hypothetical studies, our experimental results of real decisions provide no linear time preferences. In conclusion, the QALY concept needs to be modified by a weighting factor for time

Bosonic Helium droplets with cationic impurities: onset of electrostriction and snowball effects from quantum calculations

Variational MonteCarlo and Diffusion MonteCarlo calculations have been carried out for cations like Li$^+$, Na$^+$ and K$^+$ as dopants of small helium clusters over a range of cluster sizes up to about 12 solvent atoms. The interaction has been modelled through a sum-of-potential picture that disregards higher order effects beyond atom-atom and atom-ion contributions. The latter were obtained from highly correlated ab-initio calculations over a broad range of interatomic distances. This study focuses on two of the most striking features of the microsolvation in a quantum solvent of a cationic dopant: electrostriction and snowball effects. They are here discussed in detail and in relation with the nanoscopic properties of the interaction forces at play within a fully quantum picture of the clusters features

Onboard Integrated Battery Charger for EVs Using an Asymmetrical Nine-Phase Machine

This paper considers an integrated onboard charger for electric vehicles that incorporates an asymmetrical nine-phase machine and an inverter into the charging process. The charging is from three-phase mains, and it employs exclusively the power electronic components that already exist on board the vehicle and that are mandatory for the propulsion. No new elements are introduced. Moreover, the charging is achieved without any hardware reconfiguration since the existing elements and their connections are not altered during the transfer from propulsion to the charging mode. Instead, the operating principle is based on additional degrees of freedom that exist in nine-phase machines. These degrees of freedom are employed to avoid electromagnetic torque production in the machine during the charging process, although currents flow through its stator windings. The configuration operates with a unity power factor and is capable of vehicle to grid (V2G) operation as well. A detailed theoretical analysis is given, and the control for the charging/V2G and propulsion modes is discussed. Theoretical analysis is validated by experiments for charging, V2G, and propulsion operating regimes