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The feasibility of transmutation of minor actinides recycled from the spent nuclear fuel in the VVER-1000 LEU (low enriched uranium) fuel assembly as burnable poison was examined in our previous study. However, only the minor actinide vector of the VVER-440 spent fuel was considered. In this paper, various vectors of minor actinides recycled from the spent fuel of VVER-440, PWR-1000, and VVER-1000 reactors were therefore employed in the analysis in order to investigate the minor actinide transmutation efficiency of the VVER-1000 fuel assembly with different minor actinide compositions. The comparative analysis was conducted for the two models of minor actinide loading in the LEU fuel assembly: homogeneous mixing in the UGD (Uranium-Gadolinium) pins and coating a thin layer to the UGD pins. The parameters to be analysed and compared include the reactivity of the LEU fuel assembly versus burnup and the transmutation of minor actinide nuclides when loading different minor actinide vectors into the LEU fuel assembly.

This work presents the neutronic analysis of fuel design for a long-life core in a pressurized water reactor (PWR). In order to achieve a high burnup, a high enrichment U-235 is traditionally considered without special constraints against proliferation. To counter the excess reactivity, Erbium was selected as a burnable poison due to its good depletion performance. Calculations based on a standard fuel model were carried out for the PWR type core using SRAC code system. A parametric study was performed to quantify the neutronically achievable burnup at a number of enrichment levels and for a numerous geometries covering a wide design space of lattice pitch. The fuel temperature and coolant temperature reactivity coefficients as well as the small and large void reactivity coefficients are also investigated. It was found that it is possible to achieve sufficient criticality up to 100 GWd/tHM burnup without compromising the safety parameters.

This paper presents the assessment of the ex-core detectors in the Prototype Gen-IV Sodium-cooled Fast Reactor (PGSFR) in response to the movement of single primary control assembly, to evaluate the detectors’ locations and to determine a proper number of detectors. The detectors are located below the containment vessel and distributed in different ranges from the center and different azimuthal angles. Another position considered is in the radial direction of the core, at the sodium coolant gap between the outermost assembly and core shroud. To calculate the detection rate, the contribution of each fuel region to the detector and the core power distribution are required. Initially, the aforementioned contribution is generated by performing a continuous-energy forward fixed-source Monte Carlo calculation using MCNPX. The reactor kinetics code FREK simulates the power change due to an inadvertent withdrawal of a primary control assembly up to 10% from its critical position followed by full insertion of secondary control assemblies. The response from each detector location was evaluated, and consequently, the detectors located below the containment vessel, which can “see” all the fuel assemblies, responded better to the core power increase with a minor error of less than ∼0.6%. In addition, the impact of locating the detector below the containment vessel at different locations from the center or at different azimuthal angles was insignificant but several detectors should be distributed at even azimuthal angles for effective core monitoring and redundancy purposes.

The most important ageing effect on the reactor pressure vessel (RPV) is radiation embrittlement, which is mainly caused by fast neutrons during operation lifetime of nuclear reactors. The aim of this study was to investigate the DPA (displacement per atom) rate, an important parameter describing radiation damage to the RPV, and identify the position of the maximum DPA rate in the RPV of the VVER-1000/V320 reactor using the Monte Carlo code MCNP5. To reduce statistical errors in the MCNP5 simulation, the weight window technique was applied to non-repeated structures outside the reactor core. The results showed the distribution of the DPA rate in the RPV and the maximum DPA rate was found to be at the first millimeters of the RPV. Consequently, these calculations could be useful for assessment of radiation damage to the RPV of VVER reactors.

Embrittlement is one of the most important effects affecting reactor pressure vessel (RPV) aging. RPV is irradiated with neutrons and gammas, especially fast neutrons, which mainly lead to embrittlement of RPV during operation lifetime of nuclear reactors. Therefore, the radiation-induced embrittlement of the RPV should be carefully evaluated. In this paper, a preliminary calculation was performed using the MCNP5 code to identify the areas in the RPV of the VVER-1000/V320 reactor where the neutron and gamma fluxes are maximum. Also, the neutron and gamma fluence distributions on the RPV were investigated and evaluated along with their energy spectra. These calculations are the starting point for the evaluation of radiation damage to RPV of VVER reactors.

The main purpose of this study is to analyse the geomorphological charactertistics of the Dong Van Karst Plateau Geopark (DVKPG) in the Ha Giang province of Vietnam. A digital elevation model (DEM) was generated using SPOT5 imagery and elevation and slope maps were then extracted from the DEM. A geological map at the scale of 1:200,000 was constructed and used for analyzing and visualizing the carbonate rock in three dimensions. The results show that there are two types of topographic development in the study area. The first, formed by tectonic movement and affected by major faults, is distributed in a NW-SE direction. The second was formed by exogenous geomorphological processes and influenced by both major and faults. It is distributed mainly in a NE-SW direction. Geological analysis indicates that ten stratigraphic formations crop out in the study area but only six of these have correlations with karst landscapes. Carbonate rocks are mainly distributed in the Dong Van district. They cover an area of 329.7 km 2 (71.7% of the entire district and 36.5% of study area). In constrast, there is few carbonate rocks in the Quan Ba district. In the case of slope, the slope angels from 15-30° cover about 53.5% of the study area. There are 1261 karst sinkholes in the study area with an average density of 1.4 sinkholes per km 2 .

UHF TV channels are traditionally used for television broadcasting where the channels can be regarded static or slowly-varying. Due to the transition from the analog television to the digital television, the UHF TV channels 52-69 will be reallocated to other applications and there is a need of re-evaluation of these channels under the new operational environments, e.g. mobile downlink and uplink channels with antenna arrays at the transmitter and the receiver. In this paper, new results on the temporal and spatial characteristics of the wideband UHF mobile wireless signals and channels in the Digital Television (DTV) broadcasting UHF frequency bands are presented. Our analysis of DTV mobile field measurements confirms that the complex channel correlation amplitude depends on the channel phase correlation and differs considerably from the channel envelope correlation. Furthermore, the autocorrelation of the ATSC DTV transmitted signal, embedded in our received signals, degrades the received signal amplitude correlation coefficients, in comparison with the channel envelope correlation coefficients, and increases the complex received signal correlation coefficients, in comparison with the complex channel correlation coefficients, in highly correlated channels. Both downlink and uplink DTV mobile broadcast channels are investigated. The field measurement results also show that the channel envelopes are highly correlated while the channel phases are uncorrelated. This may lead to the advent of a space time code or a modulation scheme that utilizes the phase information in order to maximize the channel capacity. The results exposed in this paper are important for designers of new mobile wireless systems in order to build new wireless applications, modulation schemes, equalizers and channel-tracking algorithms in the UHF TV spectrum.

The objective of this study is to attempt a new soft computing approach for assessment of landslide susceptibility in the Luc Yen district, Yen Bai province (Viet Nam) using a novel classifier ensemble model of Naïve Bayes and Rotation Forest. First, history of 95 landslide locations was identified byfield investigations and interpretation of aerial photos. Also, the total ten landslide causal factors were selected (slope, aspect, elevation, curvature, lithology, land use, distance to roads, distance to rivers, distance to faults, and rainfall) to evaluate the spatial relationship with landslide occurrences. Information Gain technique is carried out to quantify the predictive capability of these factors. Second, landslide susceptibility assessment was carried out utilizing the novel classifier ensemble model. Finally, the performance of landslide model was validated using receiver operating characteristic curve technique, and statistical index-based evaluations. The novel classifier ensemble model indicates high prediction capability (AUC = 0.846) and relatively high accuracy (ACC = 78.77%). The study reveals that this model performs well in comparison to the other landslide models such as AdaBoost, Bagging, MultiBoost, and Random Forest. Overall, the novel classifier ensemble model is a promising method that could be used for landslide susceptibility assessment.

A new cluster-based channel envelope and phase predictor is proposed for dynamic link adaptation in broadband wireless systems, based on our observation that each Multipath Cluster (MC) has its own variation characteristics, which can be identified and traced precisely. The proposed predictor consists of a channel envelope predictor and a phase slope detector. The performance of the proposed channel predictor has been verified through numerical simulations and field test measurement data. At a channel SNR of 6.05 dB and a prediction range of 240 Orthogonal Frequency Division Multiplexing (OFDM) symbols, the obtained normalized mean square error is less than -20 dB.

Conventionally, in multi-dimensional spectral estimation techniques, each data snapshot in space is captured simultaneously. All antenna elements or sensors being used to collect data are sampled at the same time. By doing so, the size of the antenna array is proportional to the area of interest in space. The antenna array is prohibitively huge if the area that we want to cover is large. In this paper, in order to reduce the number of antenna elements in use, we propose a novel multi-dimensional spectrum estimation technique based on displacing small antenna arrays along predefined paths. It includes a data measurement technique which sequentially collects data samples within each snapshot in space according to a predefined order, and a spectral estimation technique which is based on the Discrete Fourier Transform (DFT) of the collected data. The key idea is to create a large synthetic antenna aperture by displacing a small antenna array along a predefined trajectory. Impinging waves are assumed uniform plane waves. The performance of the proposed technique is evaluated by simulation. The applications of the proposed technique include synthetic aperture radar, radar image processing and sonar systems.

In order to improve the transmit power efficiency at the Mobile Station (MS), the transmit power is usually adjusted based on feedback information from the Base Station (BS) or Channel State Information (CSI) estimated at the MS. In fast-varying channels, because of the propagation and estimation delays, and the short channel coherence time, both the feedback information and the estimated CSI may become outdated at the transmit instant, leading to a reduction in power control performance. In this paper, a new channel prediction-based adaptive power control technique is proposed for uplink transmission in Time Division Duplex (TDD) Orthogonal Frequency Division Multiplexing (OFDM) systems. Based on the predicted Channel Impulse Responses (CIRs) provided by a cluster-based time- domain channel predictor, the transmit power is allocated to each OFDM subcarrier and then, a global gain is applied to compensate for the propagation path loss. In doing this, the power control process does not rely on the feedback information from the BS nor the estimated CSI at the MS and thus, the system responsiveness, adaptivity, and power savings are improved.

In order to assess the viability of using EPAnet source code and the time domain Infrastructure Interdependencies Simulator (I2Sim) for predictive modeling, a critical failure of a municipal water supply was modeled on a university campus. During winter operations, a campus steam plant experienced a failure in operations due in part from an unobserved anomaly in the municipal water supply. The subsequent explosion which disabled campus heating caused building closures and nearly resulted in an evacuation of a major hospital. The representation of the campus municipal water distribution system was built with external stresses applied to produce system conditions equivalent to those during the failure. The data was imported directly into a test model simulating interdependent systems to see if the complete failure could then be simulated. Preliminary results have effectively recreated the incident with only some temporal errors. The results of the exercise have provided insight into operational limitations, appropriate mitigation response and water system redesign to improve its reliability.

Effective coordination is one of the most critical aspects of emergency management. Several scientific articles have described how the lack of proper coordination resulting from “limited resources, inadequate communication, misinformation, and damaged infrastructure” has negatively impacted response efforts. Problems involving the lack of consistent data moving from the incident, including the accurate description of the evolving situation, must be addressed to achieve better coordination. This paper investigates how interdependency simulators can be used to support coordination efforts and decision-making during emergency management.

In a time-varying transmission channel, the received signals are subject to frequency shifts due to the Doppler effect. The Doppler frequency is dependent on the carrier frequency and channel variation rate. In a fixed wireless channel, the channel variations are caused by scatterer motion. In this paper, we investigate analytically the Doppler effects generated by scatterer motion under different scatterer velocity distributions using the ring-of-scatterers geometric model. The proposed model considers Doppler frequency components caused by scatterer mobility to both received and reflected signals at each scatterer, and therefore is called the double Doppler model. The analytical curves are compared and statistically tested with several measurement results published in the literature. At low scatterer speeds, e.g., generated by moving foliage, the exponential velocity distribution is an appropriate model to describe the time-varying nature of the fixed wireless channels. The curve fitting results also show that our analytical model better approaches the empirical curves than the single Doppler model does. However, further investigation is still needed to find a suitable scatterer velocity distribution that closely describes the double Doppler effect in fast-variation fixed wireless channels, e.g., caused by passing vehicles.

System performance of mobile wireless communications is limited by fast channel variations, which are mostly due to the mobility of user terminals and scatterers. In order to obtain the optimal system performance, precise knowledge of the channel variations is often needed through channel prediction. A new cluster-based time-domain predictor with improved performance is proposed in this paper. Our predictor is based on the observation that multipath components within each cluster are highly correlated, while different multipath clusters share independent variations. The accuracy of the channel predictor is further enhanced by the proposed algorithm to separate the estimation noise and true channel variation information in each cluster. The principle and performance of the proposed channel predictor have been verified through numerical simulations.

Conventionally, to multi-dimensional spectral estimation techniques, each data snapshot in space is captured simultaneously in time. The size of the antenna array is dependent on the area of interest. In this paper, we propose a data measurement technique, which does not collect data samples within each snapshot in space simultaneously but sequentially along a predefined path, and a spectral estimation technique, which is based on the Discrete Fourier Transform (DFT), for the collected data. The key idea of these techniques is to create a large synthetic antenna aperture by displacing a small antenna array and by assuming uniform plan impinging waves. The performance is evaluated by simulation. The applications of the proposed techniques include synthetic aperture radar, radar processing and sonar systems.

Due to the widespread deployment of OFDM and recent advent of cognitive radio communications, robust and simple spectrum sensing techniques for OFDM signals receive significant research interest. In this paper, a time domain pilot correlation (TDPC) technique, which overcomes the complexity of FFT-based pilot sensing methods, is proposed. The TDPC technique provides an efficient and simple spectrum sensing scheme for OFDM signals using frequency domain in-band pilots. The proposed technique is based on the cyclic correlation between the complex conjugate product of adjacent OFDM signal segments and two orthogonal local references deriving from the time domain pilot sequence. Interference mitigation techniques, including periodic segmentation of the received OFDM signal, complex conjugate multiplication-based phase rotation locking, and magnitude-based correlation ratio, are adopted in this algorithm to improve the sensing performance. It is validated by simulations that the TDPC scheme achieves satisfactory sensing reliability at low SNR and is robust to both timing and frequency offsets.

ATSC standard is the digital television (DTV) standard in the North America and was developed by the Advanced Television Systems Committee. ATSC uses the maximal length pseudo-random number (PN) sequences and a correlator in order to estimate the transmission channel between the transmitter and the receiver. Conventionally, the PN511 sequence is used to estimate the channel impulse responses. In this paper, we present the performance of an enhanced channel estimation method by the application of the compound PN sequence, which is the combination of one PN511 and three PN63 sequences. The numerical results of the laboratory measurements show a good improvement in the estimation performance of the compound PN sequence over the conventional PN511 sequence. The new estimated channel impulse responses possess a lower noise floor level than the previously estimated channel impulse responses.

For the investigation of the wireless channel for the Advanced Television Systems Committee (ATSC) Terrestrial Digital Television (DTV)multipath channel transmission system, channel characterization and modeling are very important for the system designer. Based on the channel estimation procedure, we present a data analysis of the distribution of the fixed and mobile DTV multipath channels in different environment. We analyzed the power delay profiles, distributions of the root mean square (RMS) delay spread, multipath number distributions and the arrival time distributions. The modified Poisson model has been applied to compare with the statistical model of the multipath for each channel.

This paper presents our research results on the Digital Television (DTV) signals, measured in the mobile receive diversity channels. The measurements were conducted in the TV frequency band of 788–794 MHz in different types of environments. The mobile receiver was equipped with two antennas sepparated by 6 wavelengths. The presented results include the signal envelope cross-correlation, evaluated with a global and a local means; the level crossing rate and the average fade duration, evaluated with and without the receive diversity; and the diversity gain achieved when three combining techniques, i.e. diversity selection, equal gain and maximal ratio combining, are in used.

With the emergence of the multi-antenna systems, the spatial information becomes particularly significant to the modern communications systems. In this paper we present a new technique to describe and to characterize the channels and systems in space and in wave vector domains. First, we review briefly the wave vector concept, the wave vector spectrum and the 3-dimensional (3D) Fourier transform. Then a set of new impulses and new kernel functions is defined in order to establish a tool to characterize the communications channels and systems. The applications of each kernel function are also discussed. This new technique is a promising and a powerful tool to design and optimize the Multiple-Input Multiple-Output (MIMO) communications systems. The results in this paper are limited to the plane wave scenario.

UHF channels are traditionally used for television broadcasting where the channels can be regarded static or slowly-varying. Since the advent of the unlicensed and cognitive radio, there is a need of re-evaluation the channels in UHF frequency band under the new application environments. In this paper, new results on the temporal and spatial characteristics of the wideband UHF mobile wireless signals and channels in the digital television (DTV) broadcasting UHF frequency bands are presented. Our analysis of DTV mobile field measurements shows that the complex channel correlation magnitude depends on the channel phase correlation and is considerably different from the channel envelope correlation. Furthermore, the transmitted signal autocorrelation is embedded in the received signal correlation and makes it different from the channel correlation.

The utilization of multiple antennas and space–time codes in multiple-input and multiple-output (MIMO) communication systems significantly improves the transmission channel capacity without using additional bandwidth and power. The improvement is achieved by decomposing the spatial structure of transmission channels and performing appropriate temporal and spatial multiplexing. In this paper, we propose a novel theoretical framework for MIMO channel modeling and characterization in order to facilitate the MIMO system design and performance evaluation. The channels are represented in space, time, wave vector, and frequency domains while the space–time and wave vector–frequency interdependences are considered. A realization of the theoretical framework, in a form of a practical framework, is also proposed to address the channel modeling and characterization at both transmitter and receiver sides. The utilization of the practical framework in MIMO communication system design is discussed to illustrate its applications in realistic scenarios. The angle of arrival estimation based on the proposed practical framework using field test measurement data is also presented as illustrative examples.