Quantum Two-State Dynamics Driven by Stationary Non-Markovian Discrete Noise: Exact Results

We consider the problem of stochastic averaging of a quantum two-state dynamics driven by non-Markovian, discrete noises of the continuous time random walk type (multistate renewal processes). The emphasis is put on the proper averaging over the stationary noise realizations corresponding, e.g., to a stationary environment. A two state non-Markovian process with an arbitrary non-exponential distribution of residence times (RTDs) in its states with a finite mean residence time provides a paradigm. For the case of a two-state quantum relaxation caused by such a classical stochastic field we obtain the explicit exact, analytical expression for the averaged Laplace-transformed relaxation dynamics. In the limit of Markovian noise (implying an exponential RTD), all previously known results are recovered. We exemplify new more general results for the case of non-Markovian noise with a biexponential RTD. The averaged, real-time relaxation dynamics is obtained in this case by numerically exact solving of a resulting algebraic polynomial problem. Moreover, the case of manifest non-Markovian noise with an infinite range of temporal autocorrelation (which in principle is not accessible to any kind of perturbative treatment) is studied, both analytically (asymptotic long-time dynamics) and numerically (by a precise numerical inversion of the Laplace-transformed averaged quantum relaxation)

Magnetically Responsive Silicon Carbide Whiskers for Enhanced Nanocomposite Materials

Boeing’s 787 Dream Liner, GE’s wind turbine blades, and Ferrari’s F1 chassis demonstrate the accomplishments of designed directionality in carbon fiber/epoxy composites. The aerospace, energy and transportation industries demand composite material with enhanced multifunctional properties including ultimate strength and toughness. Despite sizeable improvements, composite utilization is limited by the fiber’s low surface-area-to-volume ratio (specific surface). Orientation in man-made composites has been the key to effective strengthening of materials under mechanical load and compensating for intrinsic limitations of the current technology. Nanocomposites can drive performance to new heights by increasing the fiber to matrix interaction. Thus far, the embedding of nanomaterials into composites has been achieved, but directional arrangement has proved to be a challenging task. Even with advances in insitu, shear, and stress orientation, these methods are both difficult to control and unreliable, hampering nanocomposite improvements. Therefore, the implementation of nanomaterials with a natural ability to orient along a magnetic field will create a controlled system with precisely designed morphology. To this end, the proposed project has develop an effective approach for the design of magnetically active nanowhiskers to form 2D aligned structures in a polymer matrix, creating novel nanocomposites with enhanced mechanical properties

Comparison Metrics for Time-histories: Application to Bridge Aerodynamics

Wind effects can be critical for the design of lifelines such as long-span bridges. The existence of a significant number of aerodynamic force models, used to assess the performance of bridges, poses an important question regarding their comparison and validation. This study utilizes a unified set of metrics for a quantitative comparison of time-histories in bridge aerodynamics with a host of characteristics. Accordingly, nine comparison metrics are included to quantify the discrepancies in local and global signal features such as phase, time-varying frequency and magnitude content, probability density, nonstationarity and nonlinearity. Among these, seven metrics available in the literature are introduced after recasting them for time-histories associated with bridge aerodynamics. Two additional metrics are established to overcome the shortcomings of the existing metrics. The performance of the comparison metrics is first assessed using generic signals with prescribed signal features. Subsequently, the metrics are applied to a practical example from bridge aerodynamics to quantify the discrepancies in the aerodynamic forces and response based on numerical and semi-analytical aerodynamic models. In this context, it is demonstrated how a discussion based on the set of comparison metrics presented here can aid a model evaluation by offering deeper insight. The outcome of the study is intended to provide a framework for quantitative comparison and validation of aerodynamic models based on the underlying physics of fluid-structure interaction. Immediate further applications are expected for the comparison of time-histories that are simulated by data-driven approaches

執筆者紹介

We consider the problem of stochastic averaging of a quantum two-state dynamics driven by non-Markovian, discrete noises of the continuous time random walk type (multistate renewal processes). The emphasis is put on the proper averaging over the stationary noise realizations corresponding, e.g., to a stationary environment. A two state non-Markovian process with an arbitrary non-exponential distribution of residence times (RTDs) in its states with a finite mean residence time provides a paradigm. For the case of a two-state quantum relaxation caused by such a classical stochastic field we obtain the explicit exact, analytical expression for the averaged Laplace-transformed relaxation dynamics. In the limit of Markovian noise (implying an exponential RTD), all previously known results are recovered. We exemplify new more general results for the case of non-Markovian noise with a biexponential RTD. The averaged, real-time relaxation dynamics is obtained in this case by numerically exact solving of a resulting algebraic polynomial problem. Moreover, the case of manifest non-Markovian noise with an infinite range of temporal autocorrelation (which in principle is not accessible to any kind of perturbative treatment) is studied, both analytically (asymptotic long-time dynamics) and numerically (by a precise numerical inversion of the Laplace-transformed averaged quantum relaxation)

Successful Completion of the Largest Shipment of Russian Research Reactor High-Enriched Uranium Spent Nuclear Fuel from Czech Republic to Russian Federation

On December 8, 2007, the largest shipment of high-enriched uranium spent nuclear fuel was successfully made from a Russian-designed nuclear research reactor in the Czech Republic to the Russian Federation. This accomplishment is the culmination of years of planning, negotiations, and hard work. The United States, Russian Federation, and the International Atomic Energy Agency have been working together on the Russian Research Reactor Fuel Return (RRRFR) Program in support of the Global Threat Reduction Initiative. In February 2003, RRRFR Program representatives met with the Nuclear Research Institute in Rež, Czech Republic, and discussed the return of their high-enriched uranium spent nuclear fuel to the Russian Federation for reprocessing. Nearly 5 years later, the shipment was made. This paper discusses the planning, preparations, coordination, and cooperation required to make this important international shipment

Uloga javnog bilježnika u sprječavanju pranja novca i financiranja terorizma

Rad se bavi ulogom javnih bilježnika u sprječavanju pranja novca i financiranja terorizma. U prvom se dijelu rada donosi pregled zakonodavnog okvira kojim su uspostavljene ovlasti javnog bilježnika kao osobe koja u obavljanju profesionalne djelatnosti sudjeluje u ime ili za račun svoje stranke u financijskoj transakciji ili transakciji koja uključuje nekretnine ili pruža stranci pomoć u planiranju ili provođenju određenih vrsta transakcija da provede mjere, radnje ili postupke kojima se sprječava pranje novca i financiranje terorizma. Raščlanjuje se model i problematiziraju se određeni aspekti predviđenog postupka s obzirom na poseban položaj javnih bilježnika u sudjelovanju u financijskoj transakciji koju se nadzire i ako je sumnjiva, o njoj obavještava Ured za sprječavanje pranja novca. Osobita se pozornost obraća ranjivosti javnobilježničke službe u odnosu na pranje novca i financiranja terorizma i preporukama za njezino ublažavanje. Drugi dio rada obrađuje kazneno djelo pranja novca s naglaskom na položaj javnog bilježnika kao garanta za sprječavanje pranja novca. Riječ je o temi koja je uzimajući u obzir prirodu javnobilježničkog posla praktično važna, ali je istodobno i zapostavljena u domaćoj kaznenopravnoj literaturi. S obzirom na to da Kazneni zakon postavlja odgovornost kod pranja novca vrlo široko te propisuje, između ostaloga, kažnjivost i za nehaj, za javnog je bilježnika od posebnog značaja da poznaje pravni okvir svoje odgovornosti. Autori stoga objašnjavaju garantni položaj javnog bilježnika u opisanom kontekstu i daju preporuke za zakonito postupanje, vodeći računa pritom na bitne odredbe Kaznenog zakona i Zakona o sprječavanju pranja novca i financiranja terorizma. Osim toga, u radu se upućuje i na stajališta hrvatske sudske prakse. Zauzimaju se i vlastita shvaćanja o pojedinim pitanjima koja su teorijski i praktično sporna