Success Probability Assessment Based on Information Entropy

The Bayesian method is superior to the classical statistical method on condition of small sample test. However, its evaluation results are not so good if subjective prior information is intervened. The success probability assessment about the success or failure tests of weapon products focussed in this paper, and a fusing evaluation method based on information entropy is proposed. Firstly, data from equivalent surrogate tests is converted into the prior information of an equivalent source by the information entropy theory. Secondly, the prior distribution of the success probability is identified via the Bootstrap method, and the posterior distribution is provided by the Bayesian method with the information of prototype tests in succession. Lastly, an example is given, and the results show that the proposed method is effective and valuable.Defence Science Journal, 2010, 60(3), pp.271-275, DOI:http://dx.doi.org/10.14429/dsj.60.35

qecGPT: decoding Quantum Error-correcting Codes with Generative Pre-trained Transformers

We propose a general framework for decoding quantum error-correcting codes with generative modeling. The model utilizes autoregressive neural networks, specifically Transformers, to learn the joint probability of logical operators and syndromes. This training is in an unsupervised way, without the need for labeled training data, and is thus referred to as pre-training. After the pre-training, the model can efficiently compute the likelihood of logical operators for any given syndrome, using maximum likelihood decoding. It can directly generate the most-likely logical operators with computational complexity $\mathcal O(2k)$ in the number of logical qubits $k$, which is significantly better than the conventional maximum likelihood decoding algorithms that require $\mathcal O(4^k)$ computation. Based on the pre-trained model, we further propose refinement to achieve more accurately the likelihood of logical operators for a given syndrome by directly sampling the stabilizer operators. We perform numerical experiments on stabilizer codes with small code distances, using both depolarizing error models and error models with correlated noise. The results show that our approach provides significantly better decoding accuracy than the minimum weight perfect matching and belief-propagation-based algorithms. Our framework is general and can be applied to any error model and quantum codes with different topologies such as surface codes and quantum LDPC codes. Furthermore, it leverages the parallelization capabilities of GPUs, enabling simultaneous decoding of a large number of syndromes. Our approach sheds light on the efficient and accurate decoding of quantum error-correcting codes using generative artificial intelligence and modern computational power.Comment: Comments are welcom

Characterising Gas Hydrate Deposits on New Zealand's Southern Hikurangi Margin using Seismic Reflection Data

Reprocessed Bruin 2D seismic data (recorded in 2006) from New Zealand Hikurangi Margin are presented and analyzed to show the presence of gas hydrates. We choose six seismic lines that each showed bottom-simulating reflections (BSRs) that are important indicators for the presence of gas hydrate. The aim is to obtain a higher resolution image of the shallow subsurface structures and determine the nature of the gas hydrate system in this area. To further investigate the presence of Gas Hydrates was undertaken. There is a strong correlation between anomalous velocities and the depths of BSRs, which supports the presence of gas hydrates in the research area and is useful for detecting areas of both free gas and gas hydrate along the seismic lines. The combination of high-resolution seismic imaging and velocity analysis is the key method for showing the distribution of gas hydrates and gas pockets in our research area. The results indicate that the distribution of both free gas and gas hydrate is strongly localized. The Discussion Chapter gives several concentrated gas hydrate deposits in the research area. Idealized scenarios for the formation of the gas hydrates are proposed. In terms of identifying concentrated gas hydrate deposits we propose the identification of the following key seismic attributes: 1) existence of BSRs, 2) strong reflections above BSRs in the gas hydrate stability zone, 3) enhanced reflections related to free gas below BSRs, 4) appropriate velocity anomalies (i.e. low velocity zones beneath BSRs and localized high-velocity zones above BSRs). This study contributes to the understanding of the geological conditions and processes that drives the deposition of concentrated gas hydrate deposits on this part of the Hikurangi Margin

Success Probability Assessment Based on Information Entropy

The Bayesian method is superior to the classical statistical method on condition of small sample test. However, its evaluation results are not so good if subjective prior information is intervened. The success probability assessment about the success or failure tests of weapon products focussed in this paper, and a fusing evaluation method based on information entropy is proposed. Firstly, data from equivalent surrogate tests is converted into the prior information of an equivalent source by the information entropy theory. Secondly, the prior distribution of the success probability is identified via the Bootstrap method, and the posterior distribution is provided by the Bayesian method with the information of prototype tests in succession. Lastly, an example is given, and the results show that the proposed method is effective and valuable

Damage constitutive model of lunar soil simulant geopolymer under impact loading

Lunar base construction is a crucial component of the lunar exploration program, and considering the dynamic characteristics of lunar soil is important for moon construction. Therefore, investigating the dynamic properties of lunar soil by establishing a constitutive relationship is critical for providing a theoretical basis for its damage evolution. In this paper, a split Hopkinson pressure bar (SHPB) device was used to perform three sets of impact tests under different pressures on a lunar soil simulant geopolymer (LSSG) with sodium silicate (Na2SiO3) contents of 1%, 3%, 5% and 7%. The dynamic stress–strain curves, failure modes, and energy variation rules of LSSG under different pressures were obtained. The equation was modified based on the ZWT viscoelastic constitutive model and was combined with the damage variable. The damage element obeys the Weibull distribution and the constitutive equation that can describe the mechanical properties of LSSG under dynamic loading was obtained. The results demonstrate that the dynamic compressive strength of LSSG has a marked strain-rate strengthening effect. Na2SiO3 has both strengthening and deterioration effects on the dynamic compressive strength of LSSG. As Na2SiO3 grows, the dynamic compressive strength of LSSG first increases and then decreases. At a fixed air pressure, 5% Na2SiO3 had the largest dynamic compressive strength, the largest incident energy, the smallest absorbed energy, and the lightest damage. The ZWT equation was modified according to the stress response properties of LSSG and the range of the SHPB strain rate to obtain the constitutive equation of the LSSG, and the model's correctness was confirmed

Infiltration sintering of WCu alloys from copper-coated tungsten composite powders for superior mechanical properties and arc-ablation resistance

W70Cu30(W-30 wt.% Cu) alloys were fabricated using cold pressing and infiltration sintering methods from two types of powders, i.e., mixed copper-tungsten (M-Cu-W) powders and our newly developed copper-coated tungsten composite (Cu@W) powders. Microstructure, mechanical and arc-ablation properties of the W70Cu30 alloys were investigated, and the mechanism of enhanced physical/mechanical properties and arc-erosion resistance of the W70Cu30 alloys was discussed. For the W70Cu30 alloys prepared using the Cu@W powders, their physical properties, including hardness, electrical conductivity and relative density were much better than those prepared from the M-Cu-W powders. The W70Cu30 alloys fabricated from the Cu@W powders were free of cracks, and showed homogenous distributions of W and Cu network structures. Whereas for the alloys prepared from the M-Cu-W powders, segregation of Cu was observed and the segregation size was about 40–100 μm. Characterization of arc-erosion morphologies of the W70Cu30 alloys prepared with the Cu@W powders revealed the occurrence of evaporation of Cu phase; whereas that of W70Cu30 alloys prepared with the M-Cu-W powders revealed the occurrence of the sputtering of Cu. After arc breakdown for 200 times, mass loss of alloys made using the mixed powders was twice as much as those made using the coated composite powders. Based on the experimental results and theoretical analysis, an arc breakdown mechanism of the WCu-C alloys using the composite powders was proposed which is attributed to the formation of a homogeneous Cu-Cu network structure to uniformly disperse arc energy and dissipate the generated heat, thus prolonging the service life of the WCu alloy contacts

Analysis of mechanism and optimal value of urban built environment resilience in response to stormwater flooding

The concept of urban resilience focuses on understanding the process and mechanisms of disaster occurrence, providing innovative approaches to address stormwater flooding. However, existing studies primarily concentrate on enhancing overall system resilience, with limited research examining the temporal progression from stormwater disturbance to flood generation. To fill this gap, this study categorizes the development process of stormwater flooding into three periods: disturbance resistance (DR), adjustment and adaptation (AA), and rapid recovery (RR). Using the SWMM (Storm Water Management Model) software, 27 representative parcels in the Beijing-Tianjin-Hebei region of China were simulated. By sequentially considering single-indicator control variables, resilience indicators that significantly impact the three periods were identified through the construction of a stormwater flooding resilience indicator library. Subsequently, resilience models for each disaster phase were constructed using the BP (Back Propagation) neural network, and genetic algorithms were employed to optimize the models and determine the optimal values of resilience indicators for each period. Finally, the research findings were summarized into a resilience design method for the built environment to address stormwater flooding, accompanied by a guide for improving stormwater flooding resilience.The study reveals the following key findings: (1) the influence of physical and spatial elements in the built environment on stormwater flooding formation varies across different stages of the disaster process; (2) distinct resilience indicators operate at different times and in different ways throughout the entire stormwater flooding resilience process; (3) enhancing stormwater flooding resilience in the built environment does not necessarily require setting specific threshold values for each influencing indicator; instead, an optimal single value emerges when multiple indicators interact. Moreover, when multiple indicators interact, an optimal combination module with the best value for a single indicator exists. This study investigates the complete cycle from storm disturbance to flood disaster formation, offering both solutions for cities to mitigate storm flood disasters and advancing theoretical research on urban storm flood resilience while fostering interdisciplinary integration

Identifying the optimization potential for urban GI by linking supply and demand of ecosystem services under multi-scenarios a case study of Tianjin, China

Quantitative research on the supply and demand of urban green infrastructure (GI) ecosystem services (ES) can play a crucial role in supporting ecological governance, which is vital for enhancing the health and well-being of residents and promoting sustainable development. However, current supply and demand studies often fail to consider the complexity and diversity of local climates and economic status, leading to suboptimal outcomes in urban greening programs. Therefore, there is an urgent need to incorporate the diversity and variability of demand for ES in decision-making processes for urban GI planning. To address this issue, this study proposes a multi-development scenario-based supply and demand modelling framework that measures the supply and demand of ES. By using the central city of Tianjin, China, as a case study, the resulting GI construction potential zoning and optimization strategies are determined to achieve the multiple environmental-social-economic benefits of GI. The results show that the supply and demand levels of GI in the study area are significantly spatially heterogeneous, with the demand levels of GI varying considerably under different development scenarios. Furthermore, the demand for GI is highest under the ecological priority scenario. Based on the relationship between the supply and demand of ES, the study area is classified into four zones, including a GI supply deficit zone, a supply surplus zone, a low-level balance zone, and a high-level balance zone. The area of each zone decreases in turn, indicating that the study area as a whole is in a state of mismatch between the supply and demand of ES. Finally, the study area is divided into seven GI construction potential zones based on the degree of scarcity and development orientation. The proposed planning scheme helps to achieve dynamic matching goals of ES supply and demand and provides valuable insights for policymakers to coordinate urban resources and promote sustainable development

Terahertz Rectangular Waveguides by UV-LIGA with Megasonic Agitation

This paper researches the fabrication of a WR2.8 terahertz rectangular waveguide operating at the frequency ranging from 260 GHz to 400 GHz via UV-LIGA technology (UV-lithography, electroplating, and molding). In the process, megasonic agitation is applied to improve the mechanical properties and internal surface roughness of the WR2.8 rectangular waveguide. The effects of process parameters on the properties of structures are discussed, and optimized parameters are obtained to achieve accurate geometry dimensions. In addition, the highly crosslinked SU-8 is reliably removed from structures without damage through a synthesis method. The accuracy of the height and width of the WR2.8 rectangular waveguide is 5 µm and 2 µm, respectively, and the measured internal surface roughness is 79.6 nm. Moreover, experimental measurements and numerical simulations of the waveguide are conducted, and the difference between the two is also highlighted