Pool Type Research Articles

Research on Person Re-Identification through Local and Global Attention Mechanisms and Combination Poolings.

This research proposes constructing a network used for person re-identification called MGNACP (Multiple Granularity Network with Attention Mechanisms and Combination Poolings). Based on the MGN (Multiple Granularity Network) that combines global and local features and the characteristics of the MGN branch, the MGNA (Multiple Granularity Network with Attentions) is designed by adding a channel attention mechanism to each global and local branch of the MGN. The MGNA, with attention mechanisms, learns the most identifiable information about global and local features to improve the person re-identification accuracy. Based on the constructed MGNA, a single pooling used in each branch is replaced by combination pooling to form MGNACP. The combination pooling parameters are the proportions of max pooling and average pooling in combination pooling. Through experiments, suitable combination pooling parameters are found, the advantages of max pooling and average pooling are preserved and enhanced, and the disadvantages of both types of pooling are overcome, so that poolings can achieve optimal results in MGNACP and improve the person re-identification accuracy. In experiments on the Market-1501 dataset, MGNACP achieved competitive experimental results; the values of mAP and top-1 are 88.82% and 95.46%. The experimental results demonstrate that MGNACP is a competitive person re-identification network, and that the attention mechanisms and combination poolings can significantly improve the person re-identification accuracy.

Fuzzy reliability algorithm for the shutdown system of research reactor

Abstract Probabilistic safety assessment (PSA) has been applied to evaluate the safety of nuclear reactor systems. The results of PSA are used by designers, utilities and regulatory body to confirm the reactor design, to change operation procedures, to enhance the reliability of safety systems, or to modify regulation. Fault tree analysis (FTA) has been used as a deductive means for PSA. System components are assumed to always have defined failure probabilities; however, in reality this assumption is questionable and sometimes there is insufficient data about the failure probability of some components. To solve this problem, fuzzy approaches have been proposed and implemented. The aim of this study is to apply a fuzzy reliability algorithm to estimate basic events failure probabilities for the shutdown system of a research reactor. The reactor is a 22 MW light water open pool type material test reactor and the shutdown system is responsible for the fast shutdown of the reactor whenever safety limits are exceeded. Then, to illustrate the ability of the algorithm, the results are compared with real basic event failure probabilities. The results verify the competence of the algorithm and confirm that it can be applied as an alternative method when quantitative data are not available. Also, a risk importance measure is done on the fault tree of the shutdown system to illustrate which components need to be focused for improvements to achieve the safe operation of shutdown system.

Gene pool, classification and its importance in modern crop improvement program

Alleles present in a population at a given period are referred to as the gene pool. It is the total amount and variety of genes and alleles available for transmission to the next generation in a sexually reproducing population. In comparison to formal taxonomy, Harlan and Wet identified types of gene pools as main, secondary, tertiary, and quaternary gene pools for the classification of each crop and its related species. The total quantity of genes, types and variants of genes, proportion, and distribution of genes are all revealed by studying the gene pool of a population. Selection, mutation, gene flow, and genetic drift are evolutionary mechanisms that influence a population’s gene pool. The number of genes and the number of people who carry these genes determine the size of the gene pool. Because of chance events, the number of each gene in a gene pool might shift over time. As a result, the goal of this review study is to evaluate the gene pool, classification, and importance of the gene pool in modern crop development programs.

Improving the RELAP5 code modeling of the siphon break effect in a pool type research reactor

Improving the RELAP5 code modeling of the siphon break effect in a pool type research reactor

Best Estimate Plus Uncertainty Analysis of Station Blackout Transient in Pool-Type Research Reactor

Simulation of a station blackout (SBO) scenario was carried out for an open pool–type nuclear research reactor. The SBO transient was analyzed using the best estimate (BE) thermal-hydraulic code RELAP5/MOD3.2 to evaluate the performance of safety systems and inherent thermal inertia provided by the reactor pool in ensuring adequate core cooling during a prolonged SBO condition lasting up to 7 days. This encompasses assessment of cooling provided by battery-operated auxiliary pumps in the initial phase followed by setup of the natural convection cooling mode for the extended period. Best Estimate Plus Uncertainty (BEPU) methodology was applied for assessment of safety margins. This involved estimation of required simulations using the Wilks first-order formulation to achieve results within the tolerance limit of 95/95. Identification of relevant uncertainties and their propagation was carried out; subsequently, a case matrix for 59 simulation runs was generated using the Latin hypercube sampling method. The upper/lower bounds of uncertainty results were analyzed and compared with the BE code results. Later, sensitivity analysis was carried out using sensitivity coefficients generated using the Pearson and Spearman coefficient. The results show that the values of the crucial thermal-hydraulic parameters obtained with the tolerance limit of 95/95 met the acceptance criteria, with adequate safety margins.

Understanding the impacts of dark pools on price discovery

I study how crossing networks, a type of dark pool, affect price discovery and market liquidity in the presence of noisy and heterogeneous trader signals. I identify a buffer function of crossing networks that helps mitigate traders’ losses from false signals. Additionally, I uncover an amplification effect. That is, when signal precision is high, crossing networks enhance price discovery. By contrast, when signal precision is low, crossing networks impair price discovery. These insights reconcile conflicting empirical evidence, yielding novel predictions and regulatory recommendations for equity and emerging markets.

Spatio-temporal usage of water sources by Black-cheeked Lovebirds Agapornis nigrigenis: implications for conservation planning

Summary The Black-cheeked Lovebird Agapornis nigrigenis has a highly restricted range in dry south-western Zambia, where its distribution is clumped and localised in association with mopane Colophospermum mopane woodland and permanent water pools. Fieldwork and monitoring over 30 months between December 2018 and October 2021 established that the lovebirds’ usage of pools for drinking was higher towards the centre of the bird’s distribution and influenced by the pools’ proximity to mopane woodlands, surrounding tree cover, and level of human activity. Of the four pool types available for use by lovebirds (i.e. mopane, grassland, river, and artificial), mopane and grassland pools were disproportionally susceptible to drying out in the dry season, hence showed greater variation in numbers of visiting birds compared with the other two types. Lovebirds showed a preference for pools with a perimeter of <50 m and tended to avoid those with a perimeter >100 m, consistent with a positive association between pool size and human activity. Convergence between humans and lovebirds in dependence on water resources and mopane woodland points to the need to find ways to overcome potential conflicts. Such ways include creating small, shallow-sided, undisturbed pools in or near mopane woodland, extending water retention in existing mopane pools, and enhancing the capacity of artificial pools to meet the needs of the lovebirds.

Invertebrate community composition differs between restored and natural vernal pools

The loss of freshwater wetlands worldwide has underscored the importance of restoration to enhance biodiversity and functional objectives. While aquatic invertebrate communities within restored perennial freshwaters are well studied, few studies have occurred in the greatly reduced habitat of seasonal wetlands, such as vernal pools. California vernal pools have experienced high habitat loss and support many threatened or endangered invertebrate species. We compared 90 natural and 90 restored vernal pools of different ages across 10 sites throughout California and Southern Oregon using the Sars' method. Large branchiopod abundance, total invertebrate abundance, class richness, and community composition were assessed between pool types (natural vs. restored) and along environmental gradients (e.g. site, pool depth, surface area, age since restoration). Large branchiopod and total invertebrate abundance were 215 and 274% higher in natural pools than restored pools, but class richness was not different. Community composition was significantly different and driven by greater abundances of vernal pool fairy shrimp, San Diego fairy shrimp, Ostracoda, Cladocera, and Copepoda in natural pools. Few environmental or habitat variables explained patterns in richness or abundance. Our work demonstrates that restored pools, even those decades old, are different than natural pools. Future mitigation and monitoring guidelines for restored vernal pools should include quantitative evaluations for aquatic invertebrates. Restored pools are not adequate compensation for lost natural pools because they do not have the same ecological functions and values.

Numerical analysis of sodium-argon two-phase flow in narrow channels under severe accident conditions in pool type SFR

A two-phase flow model for sodium-argon mixture flow through the reactor vessel head penetrations under the energetic core disruptive accident in a sodium fast reactor (SFR) is presented. The model evaluates the total sodium mass in sodium-argon mixture released to the reactor containment building (RCB) through penetrations. The driving pressure at the penetration entrance is given as input. The two-phase frictional and local pressure drops, inertial and piezo-metric heads are accounted for in the model. Depending on the argon volume fraction, either a homogenous or separated flow approach is adopted to evaluate the mixture flow. Reactor-scale analysis show that the presence of argon in vessel head penetrations can significantly mitigate the total sodium release mass during the slug impact phase. Also, the two-phase frictional pressure drop plays a mitigating role and needs to be included in the model formulation to avoid overestimation of the sodium release mass. Fluid-structure interaction effects such as vessel head bending and hold-down bolt elongation have negligible influence on sodium release mass as long as the deformations are within the elastic limit. The model is conceived to be part of an integrated code system to evaluate the sodium fire and the maximum RCB pressure under severe accident conditions in a pool-type SFR.

Using oscillatory and aperiodic neural activity features for identifying idle state in SSVEP-based BCIs reduces false triggers

Objective. In existing studies, rhythmic (oscillatory) components were used as main features to identify brain states, such as control and idle states, while non-rhythmic (aperiodic) components were ignored. Recent studies have shown that aperiodic (1/f) activity is functionally related to cognitive processes. It is not clear if aperiodic activity can distinguish brain states in asynchronous brain–computer interfaces (BCIs) to reduce false triggers. In this paper, we propose an asynchronous method based on the fusion of oscillatory and aperiodic features for steady-state visual evoked potential-based BCIs. Approach. The proposed method first evaluates the oscillatory and aperiodic components of control and idle states using irregular-resampling auto-spectral analysis. Oscillatory features are then extracted using the spectral power of fundamental, second-harmonic, and third-harmonic frequencies of the oscillatory component, and aperiodic features are extracted using the slope and intercept of the first-order polynomial of the spectral fit of the aperiodic component under a log-logarithmic axis. The process produces two types of feature pools (oscillatory, aperiodic features). Next, feature selection (dimensionality reduction) is applied to the feature pools by Bonferroni corrected p-values from two-way analysis of variance. Last, these spatial-specific statistically significant features are used as input for classification to identify the idle state. Main results. On a 7-target dataset from 15 subjects, the mix of oscillatory and aperiodic features achieved an average accuracy of 88.39% compared to 83.53% when using oscillatory features alone (4.86% improvement). The results demonstrated that the proposed idle state recognition method achieved enhanced performance by incorporating aperiodic features. Significance. Our results demonstrated that (1) aperiodic features were effective in recognizing idle states and (2) fusing features of oscillatory and aperiodic components enhanced classification performance by 4.86% compared to oscillatory features alone.

Performance of a pool-type photoreactor operating in continuous mode under solar irradiation for the treatment of pollutants contained in wastewater

At present, there is no effective and sustainable treatment to remove organic micropollutants from wastewater. Solar photo-oxidation offers the possibility of a self-sustaining, energetically and ecologically compatible process based solely on the use of solar energy for treatment operations. The main scientific challenge is to operate a photoreactor in continuous mode using the solar resource, which is by nature discontinuous. To date, daily or monthly capacities have not been established. This study focuses on a photoreactor operating in continuous mode under natural solar irradiation conditions for the treatment of substances contained in wastewater. Two reactors of the flat panel and tubular type, as well as a new configuration of the pool type, were studied in order to identify the advantages and disadvantages of each reactor. The main focus of the study is on a continuously operating solar photoreactor for the treatment of wastewater containing a very wide range of substances. Using a global approach, the substances were classified according to their capacity to be degraded in order to highlight the conditions necessary to conduct a photo-oxidation treatment operation. The daily capacities and the efficiency of photo-oxidation carried out continuously under dynamic irradiation conditions were established.

Peatland pools are tightly coupled to the contemporary carbon cycle.

Peatlands are globally important stores of soil carbon (C) formed over millennial timescales but are at risk of destabilization by human and climate disturbance. Pools are ubiquitous features of many peatlands and can contain very high concentrations of C mobilized in dissolved and particulate organic form and as the greenhouses gases carbon dioxide (CO2 ) and methane (CH4 ). The radiocarbon content (14 C) of these aquatic C forms tells us whether pool C is generated by contemporary primary production or from destabilized C released from deep peat layers where it was previously stored for millennia. We present novel 14 C and stable C (δ13 C) isotope data from 97 aquatic samples across six peatland pool locations in the United Kingdom with a focus on dissolved and particulate organic C and dissolved CO2 . Our observations cover two distinct pool types: natural peatland pools and those formed by ditch blocking efforts to rewet peatlands (restoration pools). The pools were dominated by contemporary C, with the majority of C (~50%-75%) in all forms being younger than 300 years old. Both pool types readily transform and decompose organic C in the water column and emit CO2 to the atmosphere, though mixing with the atmosphere and subsequent CO2 emissions was more evident in natural pools. Our results show little evidence of destabilization of deep, old C in natural or restoration pools, despite the presence of substantial millennial-aged C in the surrounding peat. One possible exception is CH4 ebullition (bubbling), with our observations showing that millennial-aged C can be emitted from peatland pools via this pathway. Our results suggest that restoration pools formed by ditch blocking are effective at preventing the release of deep, old C from rewetted peatlands via aquatic export.

Discharge Simulation of an MTR Pool Type RR due to a Break in the Reactor Tank

Discharge Simulation of an MTR Pool Type RR due to a Break in the Reactor Tank

Spatiotemporal Variation and Quantitative Attribution of Carbon Storage Based on Multiple Satellite Data and a Coupled Model for Jinan City, China

Rapidly predicting and revealing the spatiotemporal characteristics and driving factors of land-use changes in carbon storage within megacities under different scenarios is crucial to achieving sustainable development. In this study, Jinan City (JNC) is taken as the study area, and the Markov-FLUS-InVEST model is utilized to predict and analyze the spatiotemporal variation in carbon storage in 2030 under three scenarios, namely, the natural development scenario (S1), the ecological conservation scenario (S2), and the economic development scenario (S3). The drivers of carbon storage changes were identified using an optimal parameter-based geographic detection (OPGD) model. The findings indicate that (1) land use from 2010 to 2018 shows a trend of continuous expansion of construction land and reduction in arable land. (2) The main types of carbon pools were cropland, forest, and grassland, accounting for more than 96% of the total amount. Carbon storage showed a decreasing trend from 2010 to 2018, and the main type of carbon pool that decreased was cropland. The center of gravity of carbon storage increases and decreases was located in the southern Lixia District, and the center of gravity of increase and decrease moved to the southwest by 3057.48 m and 1478.57 m, respectively. (3) From 2018 to 2030, the reductions in carbon stocks were 3.20 × 106 t (S1), 2.60 × 106 t (S2), and 4.26 × 106 t (S3), and the carbon release was about 9 times (S1), 4 times (S2), and 10 times (S3) that of the carbon sink. (4) The contribution of slope (A2) ∩ nighttime light index (B6) and elevation (A1) ∩ nighttime light index (B6) to the regional heterogeneity of carbon stocks was the largest among the interaction drivers. To sum up, this study deepens the simulation of spatial and temporal dynamics of carbon storage under land-use changes in megacities and the related driving mechanism, which can provide the basis for scientific decision-making for cities to conduct territorial spatial planning and ecological protection and restoration.

Improvement of the quality of neutron radiography beamlines in Isfahan MNSR

Recently, two external neutron beam lines have been installed in the Isfahan MNSR. This reactor is a tank in pool type with a maximum power of 30 kW, which has been in operation since 1994, and in its original design it did not have a beam tube. These two neutron beam lines are designed and installed out of the reactor tank for irradiation experiments of large objects outside the reactor core, such as neutron radiography. The results of the evaluations in the previous researches showed that these two beam lines have acceptable quality according to the ASTM-E545 standard. However, their gamma contamination were relatively high. In this study calculations and experiments have been done to reduce the gamma content of the neutron beams and to increase the ratio of thermal neutron flux to gamma dose rate. This was done through the design and installation of gamma filters in the beam lines. The results of the evaluations showed that the quality of the neutron beams has been greatly improved in terms of reducing gamma content, so that the quality rating of the beams has increased by at least two ranks.

Benchmarking exercise of indigenous Monte Carlo neutron transport code PATMOC for hexagonal full core reactor geometry

An indigenous Monte Carlo neutron transport code, named PATMOC, has been designed and developed at Bhabha Atomic Research Centre (BARC) for reactor physics design applications. The code has been extensively tested for its algorithmic accuracy against numerous international numerical benchmarks, has also been validated on practical nuclear reactor systems like Advanced Heavy Water Reactor Critical Facility (AHWR-CF) and Apsara-U pool type research reactor located at BARC, and is now in regular use for day-to-day reactor physics studies. These reactor systems and most of the benchmark problems used for the verifications and validation of the code have square lattice arrangement in the core. In this paper, we present the results of verification of PATMOC code on whole-core reactor system with hexagonal lattice arrangement of fuel elements. In this exercise, we have analyzed the High Temperature engineering Test Reactor (HTTR) whole-core benchmark for integral and differential parameters at both lattice and core level. The results demonstrate the algorithmic accuracy of the code on hexagonal reactor systems also. This exercise will help make use of this code for reactor physics design studies also for the reactor systems with hexagonal arrangement.

Calculating a Land Carbon Accounting Factor in the United States: an Example and Implications

Abstract Companies that produce and use wood for products and energy find it increasingly important to communicate the carbon balance and potential climate effects of these activities. Computing forest carbon stocks and stock changes, and emissions from operations, are often part of institutional reporting for environmental, social, and governance purposes. This article describes an example methodology to assess forest carbon changes associated with the harvesting of wood products and proposes metrics that could be used to allocate harvesting effects to individual organizations for their reporting purposes. We discuss boundaries (types of forests and carbon pools to include), spatially appropriate evaluations given uncertainty, temporal considerations, risk of reversals, and allocation of net sequestration to products sourced from the region. We also discuss the complex nature of the biogenic carbon cycle and warn about the appropriate interpretation of this methodology.

Types and morphologies of gully step pools of different process of formation in the Yuanmou dry-hot Valley

ABSTRACT Step pools are micro-geomorphology hosted in gullies which are closely related to the channel erosion rate and hydraulic characteristics of runoff. These features are widely developed in the Yuanmou dry-hot Valley area of the Central Yunnan Plateau, China. In this paper, the morphological characteristics of different types of step pools in the Yuanmou dry-hot Valley were analyzed using analysis of variance and cluster analyses. The results show that: (1) step pools can be divided into differential, bedrock, barrier, and sub-erosion step pools based on the environment of development; the bedrock and differential step pools develop on a large scale, while barrier and sub-erosion step pools develop on a small scale; (2) the width and depth of the step, the height of the step, the width of the pool, and the depth of the step of the differential type, bedrock type, and sub-erosion type step pools exhibited a significant positive correlation (P < 0.01); the height of the step and the depth of the pool of the barrier type step pools were significantly negatively correlated with the height of the step and the concave hole depth of the sub-erosion type (P < 0.01); (3) the differential type and undercurrent type step pools were seriously eroded. The study of the types and morphologies of gully step pools in the Yuanmou dry-hot Valley helps understand the formation and evolution mechanisms of erosion gullies and provides a scientific basis for monitoring and controlling soil erosion.

Review on the management of water quality for bio-mineral swimming pools in Western Europe.

In this review, we depict the state of the art concerning the water quality management of bio-mineral bathing pools, and compare these to traditional swimming pools. Bio-mineral pools use a combination of mechanic filtration, bio-filtration, and UV-treatment to disinfect the water. Studies in test tanks have shown that bio-filtration is effective in maintaining the water quality with regard to the treatment of organic pollution. Concerning biological risks, the bio-mineral pool relies on UV-treatment to degrade bacteria. Unlike chemical disinfectant treatments, UV disinfection does not lose its effectiveness in the event of high traffic in the pool. However, as only the water taken up by the filtration system is disinfected, it is essential that all the water in the pool is filtered. If the pool has a dead zone, its water is not disinfected and there is a risk of localized pathogen development. As the development of bio-mineral pools spreads in Europe, legislation gradually follows. The health parameters measured differ slightly from one country to another, but there are constants: the measurement of Escherichia coli, Enterococci, and Pseudomonas aeruginosa. In terms of biological swimming pools, regulatory homogeneity across Europe does not exist. From these comparisons, Austrian legislation segmenting water quality into 4 categories ranging from "excellent" to "poor" represents legislation that combines health and safety with indications of possible malfunctions. Next, a study of three real sites of bio-mineral pools is presented. It appears that whatever the type of pool, bio-mineral filtration makes it possible to achieve performances comparable to those encountered in chlorinated swimming pools concerning the risks associated with fecal contamination and external pollution. On the other hand, when frequentation is high, as is the case in small pools used for aquafitness, monitoring the risks of inter-bather contamination, as illustrated by the presence of Staphylococcus aureus, reveals a recurring problem. Knowing that this parameter is not evaluated in bathing waters in the natural environment and that numerous studies show that Staphyloccocus aureus are always detected, even on beaches, we propose the definition of three thresholds: i.e., 0CFU/100mL (threshold value in Wallonia) for water of excellent quality, less than 20CFU/100mL (threshold value in France) for water of very good quality, less than 50CFU/100mL (contribution of bathers by simple immersion) for good quality water, and more than 50CFU/100mL for poor quality water. This document could therefore be converted into a manual for operators on the use and management of bio-mineral baths.

The LIFUS5 separate effect test facility experimental programme

The LIFUS5 facility is a separate effect test facility aimed at investigating the heavy liquid metal-water interaction. It has been designed and constructed to withstand high pressure and temperature (i.e. up to 200 bar and up to 500 °C) and to record the fast pressure transients in heavy liquid metal melt. This type of transient is typical of a Steam Generator Tube Rupture event in a pool type Gen IV Heavy Liquid Metal cooled Fast Reactor system, and should be investigated from the safety point of view because it could potentially induce, beyond the damaging of the internal structures (HX tube bundle, above core structures, Fuel Assembly, Control Rods, etc.) several negative effects on the operation of the reactor. These include an insertion of positive reactivity into the system or reduced cooling efficiency due to steam dragging into the core. It will also have an effect on the chemistry control of the cooling. All these effects compromise the safety and the reliability of the system. The twenty years experimental programme and the different LIFUS5 configurations are presented in the paper, as well as the experimental campaigns and test matrix characterizing the heavy liquid metal-water interaction phenomena and data for codes validation.