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[en] Innovation is considered as a core element of sustainable competitive advantage in the rapidly changing environment. However, in Vietnam, researches on innovation are very rare, which are mostly general reports without underlying analyses of innovation in firms, especially determinants for innovation. Therefore, this paper focuses on analyzing critical successful factors for innovation in Vietnamese firms. Design/methodology/approach: This study used primary data through questionnaire survey from November 2015 to February 2016. Respondents were senior managers of firms located mostly at Hanoi (Northern), Hochiminh (Southern) and Danang city (Central). The questionnaire included multi-items designed to measure factors. Each item was measured by 5 point Likert scale: 1 (strongly disagree) to 5 (strongly agree). Questionnaires were administerd to 500 firms belonging to list of Vietnam Chamber of Commerce and Industry (VCCI) in these three cities with rate of 40% (Hochiminh city), 40% (Hanoi city) and Danang (20%). However, there were 360 returned questionnaires and valid to next analyses. Analysis methodologies of reliability, factor analysis and regression are utilized in this paper. Findings: We developed and tested a model of determinants for Innovation in Vietnamese firms. The major contribution of this study is testing six determinants for innovation in Vietnamese companies. The results showed that awareness of innovation, innovation strategy and policy, organization for innovation, HR for innovation and building capabilities have positive impact on innovation. Originality/value: This study makes a contribution for both academics and practitioners. For academics, this study provided one more empirical evidence of the determinants for innovation. Regarding practical implications, this study suggests that Vietnamese companies have to strengthen capabilities for employees through training, encourage generation of new ideas, rule breaking, and innovative behaviors by organizational members. Together, having high awareness of innovation, building rational innovation strategy and policy is essential factors that firms should possess and develop to enhance innovation performance. Although there is no confirmation for impact of finance on innovation level, firms should understand that increasing innovation investment can bring favorable condition to create innovation especially in SMEs.
[en] Some effective filtering methods for wrapped phase maps, a regularized phase-tracking method (RPT) without the regularization term, a multiple-parameter least-square method (MPLS), a windowed Fourier ridges method (WFR), an autocorrelation function method (ACF), and a sine/cosine average filter (SCAF), are analyzed in order to establish their transversal relationship. The analysis shows that principles of the RPT,MPLS, WFR, and ACF are equivalent and the SCAF also leads to the WFR by some extension, which elegantly unifies all these methods for filtering unwrapped phase maps
[en] Analytical solution methods for the neutron noise in a one-dimensional multi-region system in two-group theory, which have so far been based on the adjoint function technique, are extended here to using the forward Green's function technique. The forward Green's functions were calculated analytically for a noise source in a core surrounded by reflector regions at both sides. It is shown that with symbolic computation methods, the forward Green's function can be used for the calculation of the space- and frequency-dependent noise in the first order approximation for arbitrary noise sources which have an analytical representation. The properties of the induced neutron noise were investigated for vibrations of both absorbers and fuel assemblies, with two representations of the noise sources: a point-like source which corresponds to the vibrations of a fuel rod, and a finite width source which corresponds to vibrations of a fuel assembly. The contributions of the components induced by the fluctuations of the various types of macroscopic cross sections in the total noise are also discussed and the information content of the noise in the fast group is explored for the identification of fuel assembly vibrations. (orig.)
[en] There are shown some of results of study in designing and making first gaseous detectors of big sizes in Vietnam. The detectors were used for test measurement of detecting energy spectrum of the products of reaction 6Li(n,alpha)3H caused by thermal neutrons. On the spectrum there were observed two energy peaks of tritons and alpha particles separately. In the test measurement there were used two neutron isotopic sources with total output 2x1.1x107 n/s. The study was implemented at Hanoi University of Technology. (author)
[en] Fuel burnup performance has been analyzed for a pebble bed reactor with a once-through-then-out (OTTO) refueling scheme and compared with a reference multi-pass scheme. A new fuel pebble was designed by adding spherical B4C particles into its free fuel zone for controlling the infinite multiplication factor during burnup, and then reducing the axial power peak of the OTTO scheme. The objective is to maximize the fuel burnup performance of the OTTO scheme while keeping the power peak under a limit and ensuring the core criticality. Numerical calculations were performed based on the 400 MWt pebble bed modular reactor (PBMR) using the MVP code. For the fuel pebble of the PBMR containing 9 g uranium with 9.6 wt% 235U enrichment, 1600 B4C particles with a radius of 70 μm are determined to flatten the k∞ curve in the early burnup stage. The dependences of the neutronic properties of the core with the OTTO scheme on target fuel burnup show that the maximum target burnup of 74 GWd/t can be achieved so that the power peak is reduced to about 10.80 W/cm3 which is approximate that of the multi-pass scheme (10.85 W/cm3). This target burnup is about 22% less than that of the multi-pass scheme (95 GWd/t), i.e. the fuel utilization efficiency of the OTTO scheme is about 22% lower, which could be compensated by the construction and operation cost of the fuel handling system. This result also suggests that further investigations of the fuel burnup performance and other properties are needed in both neutronic and thermal hydraulic viewpoints to find out the optimal core performance.
[en] An improved inverse analysis model for fuel loading pattern (LP) optimization is proposed to reproduce a desired in-core power distribution from available fuel assemblies based on the inverse analysis of diffusion equations. In the present approach, the inverse analysis is simplified as a fixed-source problem rather than an eigenvalue problem in a previous work. By using the one-to-one correspondence between the power distribution and reactivity distribution, a target reactivity distribution is solved from a desired power distribution through the inverse analysis. The reactivity of available assemblies is evaluated using a modified effective fast-group model with a higher order correction of leakage effect. A candidate LP is determined by individually matching the reactivity of available assemblies to the target in-core reactivity distribution using a stable matching algorithm. The process of predicting the reactivity of available assemblies and matching them to the target reactivity distribution is repeated until the convergence condition is satisfied. Validation of the model has been confirmed with a reference PWR core. The model is expected to be applicable to a problem of multicycle loading pattern optimization. (author)
[en] This work presents the neutronic calculation results of a VVER-1000 assembly using SRAC with 107 energy groups in comparison with the benchmark values in the OECD/NEA report. The main neutronic characteristics which were calculated in this comparison include infinite multiplication factors (k-inf), nuclide densities as the function of burnup and pin-wise power distribution. Calculations were conducted with various conditions of fuel, coolant and boron content in coolant. (author)
[en] Attempts have been made to transmute minor actinides (MAs) in supercritical CO2-cooled and sodium-cooled fast reactor cores as burnable poison and fuel. Minor actinides are loaded uniformly in the fuel of the cores. Minor actinide loading contents were determined to minimize the burnup reactivity swing. In the S-CO2- cooled core, the burnup reactivity swing is minimized to 0.11% Δk/kk' when the MA content is 6.0 wt%. In the Na-cooled core, MA content was determined to reduce the burnup reactivity swing while maintaining the sodium void reactivity under a design limitation value of 5 $. The burnup reactivity swing of the Na-cooled core is reduced to 1.94% Δk/kk', whereas sodium void reactivity is 4.7 $ when 10.0 wt% MAs are loaded. The low burnup reactivity swing enables minimization of control rod operation during fuel burning and reduction of the control rod number to 10 in both cores, which is half of a typical sodium-cooled mixed-oxide fuel Monju core without MA loading. The MA transmutation rates in the S-CO2-cooled and Na-cooled cores are respectively equivalent to the production rates in 7 and 9 LWRs of equivalent electrical output. (authors)
[en] This paper presents the development of an automated generation of a new burnup chain for reactor analysis applications. The JENDL FP Decay Data File 2011 and Fission Yields Data File 2011 were used as the data sources. The nuclides in the new chain are determined by restrictions of the half-life and cumulative yield of fission products or from a given list. Then, decay modes, branching ratios and fission yields are recalculated taking into account intermediate reactions. The new burnup chain is output according to the format for the SRAC code system. Verification was performed to evaluate the accuracy of the new burnup chain. The results show that the new burnup chain reproduces well the results of a reference one with 193 fission products used in SRAC. Further development and applications are being planned with the burnup chain code. (author)