A high-fidelity simulation method of the control rod absorbers is implemented in the Monte Carlo code RMC. For rare-earth absorbers and B4C which have been widely researched, detailed calculations and analyses are conducted for neutronic and depletion characteristics. Using this method, three kinds of optimized control rod absorbers are proposed with higher reactivity worth and favorable burnup stability. In these new designs, the composite absorbers possess higher reactivity worth and only average 20% reactivity loss at the end of cycle (EOC). The enriched absorbers have better neutron absorbing capacity and more stable radiation resistence, and the reactivity loss of enriched B4C reduces from 90% to only 7.42% at EOC. For mixed absorbers, the best properties are found for the Dy and B4C mixture when the proportion of Dy is about 60%. The coupling of ZrH2 and Hf achieves a better control efficiency, but unfortunately the reactivity loss increases at EOC.
Security and privacy issues arise along with the research and development of industrial cyber-physical systems (ICPSs). Plenty of risk sources have been introduced into such systems due to insufficient consideration at the design stage and a lack of standards in various task scenarios in the new industrial ecology. Facing these phenomena, this chapter starts from a fundamental understanding of the importance of privacy and security, by exploring the basic principles, emerging challenges, and effective strategies. By looking into the integration of the physical and digital components that form the ICPS environments, we emphasize the critical need for countermeasures against various threats. The potential consequences of security incidents and privacy breaches are then discussed, followed by an analysis of their impact on physical infrastructure, operational continuity, sensitive data, and public safety. Furthermore, the chapter emphasizes that addressing these concerns requires a multifaceted approach. We explore various security measures, including access control, authentication, secure communication protocols, and intrusion detection and prevention systems, while also addressing privacy considerations, such as data collection practices and privacy-preserving techniques. This chapter tries to provide professionals, researchers, practitioners, and policymakers with insights and practical guidance to effectively safeguard the ICPS environments, promoting the reliable and secure operation of these systems.
Cyber-physical systems (CPSs) play an increasingly important role in critical industrial infrastructure. However, the use of communication networks leads to vulnerabilities in systems. Considering the negative effects caused by the recent attack events, guaranteeing safe and reliable operation of infrastructures is necessary. This paper proposes a dual denoising auto-encoder (DDAE) and based on which proposes a unified scheme (in the sense of sharing the DDAE models) to protect cyber-physical systems (CPS) from being eavesdropped, and to detect the typical attacks, i.e., false data injection (FDI) attacks, denial-of-service (DoS) attacks, and replay attacks. The industrial data are encrypted by the encoder of the offline-trained DDAE before transmission, and at the receiving end, the transmitted data are analyzed by a residual generator-based detection module. If the received data are trustworthy, they will be decrypted and used in the subsequent industrial processes. Otherwise, attack warnings will be triggered. The simulation results on the IEEE-57 bus system show that the proposed scheme can effectively prevent the transmitted data from being eavesdropped and can accurately detect typical cyber-physical attacks.
With the decrease of pressure during the production process of low-permeability condensate gas reservoirs, different degrees of retrograde condensate pollution appear in the area near the wellbore, resulting in a rapid decrease in the productivity of gas wells. Due to the poor physical properties of low-permeability condensate gas reservoirs, conventional single measures such as circulating gas injection and huff and puff gas injection cannot effectively relieve the condensate pollution in the near-wellbore area. For this reason, this paper explores the WH1 gas well in the W low-permeability condensate gas reservoir and conducts research on the retrograde of reverse condensate pollution in a single well. First, 12 groups of inside evaluation experiments for the decontamination of retrograde condensates are carried out using the core of the condensate gas reservoir W and 6 different agents. According to the experimental results, methanol + CO<sub>2</sub> huff and puff are selected as the optimal agent for decontamination by retrograde condensate. Secondly, by analyzing the physical properties of the W low-permeability condensate gas reservoir and the production performance parameters of the WH1 well, a three-dimensional numerical simulation model of the single well of the WH1 gas well is established, and the PVT phase state matching and production performance history matching are carried out for the model. Finally, the single-well numerical simulation model of the WH1 gas well, combined with the experimental results, is used to simulate the obturation effect of CO<sub>2</sub> injection after methanol injection. Among them, the change of reservoir physical properties in the near-wellbore area after methanol injection is simulated by the method of local grid refinement. The research shows that after the simulated well is injected with 20m3 methanol when the CO<sub>2</sub> injection volume in a single cycle is 120 × 10<sup>4</sup> m<sup>3</sup>, the injection rate is 4 × 10<sup>4</sup> m<sup>3</sup>/d, and the well soaking time is 11 days. The reservoir pollution removal effect is the best in the area near the wellbore. From the change of liquid saturation in the near-wellbore area, it can be concluded that the damage of retrograde condensate is relieved by about 87.1%. This study has formed a set of efficient technical means for removing reverse condensate pollution in W low-permeability condensate gas reservoirs. It provides some technical guidance for the formulation of a rational development mode of condensate gas reservoirs.
The changing landscape of transportation technology and traveler behavior, accelerated by recent events like COVID-19, has led to significant shifts in travel demand and vehicle miles traveled in Indiana. This study seeks to understand the long-term implications of these changes and their potential impact on passenger, freight, and micro-mobility movements across the state. To achieve this objective, this project focused on forecasting future transportation demand conditions and carrying out long-range scenario planning by accomplishing four tasks: forecasting travel demand shifts based on location-based data, evaluating medium-term inter- and intra-urban transportation demand shifts, forecasting county-level industry shifts using scenario-based growth models, and providing recommendations and guidance to the Indiana Department of Transportation (INDOT) based on the study results. Results offer improved planning for infrastructure investments and operations, the incorporation of emerging technologies into transportation planning processes, and an enhanced understanding of passenger and freight movements at the statewide and regional levels. Deliverables from this study include valuable tools and models that can help INDOT navigate potential transportation system changes and accommodate the evolving needs of the future.
Comprehensive research on reservoir rock mechanics and in-situ stress properties combined with petrophysical experiments, logging models and numerical simulation is an important means to achieve efficient development of tight sandstone oil reservoirs. In this study, a large number of rock mechanics and acoustic experiments, full-wave train array acoustic wave tests, hydraulic fracturing data and three-dimensional finite element simulations were used to study the rock mechanical properties and in-situ stress characteristics of continental tight oil reservoirs in the Yanchang Formation. The results show that under uniaxial conditions, the tight sandstone samples mainly suffer from tensional ruptures. With the increase of confining pressure, the tight sandstone samples undergo obvious shear ruptures. When the confining pressure is loaded to 35 MPa, a typical vertical shear fracture will be formed. The hydraulic fracturing calculation results show that the in-situ stress state of the target layer satisfies σ v (vertical principal stress)> σ H (maximum horizontal principal stress)> σ h (minimum horizontal principal stress). Based on the results of rock mechanics and acoustic tests, we have constructed the dynamic and static mechanical parameter conversion models of tight oil reservoirs and the logging interpretation model of current in-situ stress. Furthermore, the finite element method is used to simulate the three-dimensional structural stress field of the target layer. The simulations show that the horizontal principal stress distribution in the work area is consistent with the applied environmental stress. The σ H of the target layer is mainly distributed in 32–50 MPa, and the σ h is mainly distributed in 20–34 MPa. Both σ H and σ h are relatively high in the southern uplift of the work area; among them, σ H is usually greater than 44 MPa, and σ h is usually greater than 24 MPa. The northern part of the study area developed several grooved areas with relatively low stress values. The regions with high stress values are often distributed in bands, which may be related to the compression caused by the deformation of the strata. For shear stress, left-handed and right-handed regions usually alternate with each other. However, the extent of the left-handed area in the southern uplift area is larger than that of the right-handed area, indicating that the tight oil reservoirs in the study area are mainly affected by left-handed activities.
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