This article takes stock of some of the important contributions to the study of peacekeeping (PK). Two key topics stand out: peacekeeping burden sharing and mission effectiveness. For burden sharing, ...the theoretical foundation is the private provision of public goods and joint products. Implications for burden sharing differ whether financial or troop contributions are being shared, with the latter driven by jointly produced country-specific benefits. Financial burden sharing can also differ between United Nations (UN)-led and non-UN-led peacekeeping operations, wherein country-specific benefits are especially important for the latter. Many articles gauge peacekeeping effectiveness by the mission's ability to maintain the peace or to protect lives for a set time period. More recently, multiple criteria are raised for evaluating peacekeeping in today's world of multifaceted peacebuilding operations.
Here this work presents post-irradiation examination data on UN-U3Si5 and U3Si5 fuels at low burnup (i.e., <10–15 GWd/tHM) with Kanthal AF® cladding. The results suggest good irradiation performance ...for both the silicide and nitride-silicide composite pellets. Optical microscopy revealed that the pellet-cladding gap is still open, and limited axial cracking was observed only in UN-U3Si5 pellets. Microcracking was isolated to the U3Si5 phase in all cases and was observed in pre-irradiation and depleted pellets, indicating that it was not irradiation induced. The fission gas release was minimal for the calculated fission density achieved (2.6 – 3.15 × 1020 fiss/cm3). No fission gas bubbles were observed in the optical metallography. These results suggest acceptable swelling and fission gas behavior for both the single phase and composite compositions.
Restoring the health of degraded land is critical for overall human development as land is a vital life-supporting system, directly or indirectly influencing the attainment of the UN Sustainable ...Development Goals (UN-SDGs). However, more than 33% of the global land is degraded and thereby affecting the livelihood of billions of people worldwide. Realizing this fact, the 73rd session of the UN Assembly has formally adopted a resolution to celebrate 2021–2030 as the UN Decade on Ecosystem Restoration (UN-DER), for preventing, halting, and reversing degradation of ecosystems worldwide. While this move is historic and beneficial for both people and the planet, restoration of degraded land at different scales and levels requires a paradigm shift in existing restoration approaches, fueled by the application of applied science to citizen/community-based science, and tapping of indigenous and local knowledge to advanced technological breakthroughs. In addition, there is a need of strong political will and positive behavioral changes to strengthen restoration initiatives at the grassroot level and involvement of people from all walks of life (i.e., from politicians to peasants and social workers to scientists) are essential for achieving the targets of the UN-DER. Similarly, financing restoration on the ground by the collective contribution of individuals (crowd funding) and institutions (institutional funding) are critical for maintaining the momentum. Private companies can earmark lion-share of their corporate social responsibility fund (CSR fund) exclusively for restoration. The adoption of suitable bioeconomy models is crucial for maintaining the perpetuity of the restoration by exploring co-benefits, and also for ensuring stakeholder involvements during and after the restoration. This review underpins various challenges and plausible solutions to avoid, reduce, and reverse global land degradation as envisioned during the UN-DER, while fulfilling the objectives of other ongoing initiatives like the Bonn Challenge and the UN-SDGs.
Unsupervised anomaly detection with localization has many practical applications when labeling is infeasible and, moreover, when anomaly examples are completely missing in the train data. While ...recently proposed models for such data setup achieve high accuracy metrics, their complexity is a limiting factor for real-time processing. In this paper, we propose a real-time model and analytically derive its relationship to prior methods. Our CFLOW-AD model is based on a conditional normalizing flow frame- work adopted for anomaly detection with localization. In particular, CFLOW-AD consists of a discriminatively pretrained encoder followed by a multi-scale generative de- coders where the latter explicitly estimate likelihood of the encoded features. Our approach results in a computationally and memory-efficient model: CFLOW-AD is faster and smaller by a factor of 10× than prior state-of-the-art with the same input setting. Our experiments on the MVTec dataset show that CFLOW-AD outperforms previous methods by 0.36% AUROC in detection task, by 1.12% AUROC and 2.5% AUPRO in localization task, respectively. We open-source our code with fully reproducible experiments 1 .
The temperature-dependent effective thermal conductivity of UN-X-UO2 (X = Mo, W) nuclear fuel composite was estimated. Following the experimental design, the thermal conductivity was calculated using ...Finite Element Modeling (FEM), and compared with analytical models for 10%, 30%, 50%, and 70% (in mass) uncoated/coated UN microspheres in a UO2 matrix. The FEM results show an increase in the fuel thermal conductivity as the mass fraction of the UN microspheres increases from 1.2 to 4.6 times the UO2 reference at 2,000 K. The results from analytical models agree with the thermal conductivity estimated by FEM. The results also show that Mo and W coatings have similar thermal behaviors, and the coating thickness influences the thermal conductivity of the composite. At higher weight fractions, the thermal conductivity of the fuel composite at room temperature is substantially influenced by the high thermal conductivity coatings approaching that of UN. Thereafter, the thermal conductivity from FEM was used in the fuel thermal performance evaluation during LWR normal operation to calculate the maximum centerline temperature. The results show a significant decrease in the fuel maximum centerline temperature ranging from −94 K for 10% UN to −414 K for 70% (in mass) UN compared to UO2 under the same operating conditions.
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•Effective thermal conductivity of innovative UN-X-UO2 (X = Mo, W) nuclear fuel composite was calculated.•Simulated cases cover 10%, 30%, 50%, and 70% (in mass) uncoated/coated UN microspheres in a UO2 matrix.•Results show a thermal conductivity increase as the UN mass fraction increases (1.2 to 4.6 times that of UO2 at 2,000 K).•Fuel thermal performance during LWRs normal operation shows a decrease in the fuel maximum centerline temperature.
Oxidation of UN/U2N3-UO2 composites Costa, Diogo Ribeiro; Hedberg, Marcus; Middleburgh, Simon C. ...
Journal of nuclear materials,
02/2021, Volume:
544
Journal Article
Peer reviewed
Open access
Composite fuels such as UN-UO2 are being considered to address the lower oxidation resistance of the UN fuel from a safety perspective for use in light water reactors, whilst improving the in-reactor ...behaviour of the more ubiquitous UO2 fuel. An innovative UN-UO2 accident tolerant fuel has recently been fabricated and studied: UN microspheres embedded in UO2 matrix. In the present study, detailed oxidative thermogravimetric investigations (TGA/DSC) of high-density UN/U2N3-UO2 composite fuels (91-97 %TD), as well as post oxidised microstructures obtained by SEM, are reported and analysed. Triplicate TGA measurements of each specimen were carried out at 5 K/min up to 973 K in a synthetic air atmosphere to assess their oxidation kinetics. The mass variation due to the oxidation reactions (%), the oxidation onset temperatures (OOTs), and the maximum reaction temperatures (MRTs) are also presented and discussed. The results show that all composites have similar post oxidised microstructures with mostly intergranular cracking and spalling. The oxidation resistance of the pellet with initially 10 wt% of UN microspheres is surprisingly better than the UO2 reference. Moreover, there is no significant difference in the OOT (similar to 557 K) and MRT (similar to 615 K) when 30 wt% or 50 wt% of embedded UN microspheres are used. Therefore, the findings in this article demonstrate that the UO2 matrix acts as a barrier to improve the oxidation resistance of the nitride phases at the beginning of life conditions.
This paper proposes a novel hierarchical-adaptive threshold abnormal behavior discrimination scheme (HATAD) for Lipschitz nonlinear large-scale systems with disturbances and uncertain dynamics. Two ...layers of groups of interlinked observers, namely the supervisor and local layers, are designed. The local layer using open loop observers, switching technique, and local controllers is first developed to protect the physical system from the attack effects, where the proposed switching technique can connect the plant to the local controller under the attack conditions. At the supervisor layer, the main controllers and three types of observers are constructed to detect and discriminate the abnormal behaviors and determine the faulty unit. This architecture leads to less restrictive mathematical conditions and analyses, which ensure the stability and the L2−L∞ performance of the estimation error dynamics. To demonstrate the effectiveness of the proposed approach, a simulation study has been conducted on a large-scale system of two units of benchmark continuous stirred tank reactor (CSTR).
The topic of the research is renunciation of war as a means of international dispute settlement. As a permanent fulcrum of political philosophy and international law, war regulation applies two ...dynamically related focal approaches. They are either individually established or combined in various aspects. The first approach accepts war as a means of resolving disputes between sovereign states and creates rules for its humanization. The objective of the second approach is to determine international legal methods for war prevention. It is concluded that the current international law is neither based on, nor even aimed at a non-conflict foundation in international relations, but seeks its support in avoiding the wording "war".
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