贝克休斯

This work focuses on the comparison between two patented configurations of the Allam Cycle: the basic scheme and the recompressed one. The two Allam cycle schemes, including the cryogenic CO2 purification and compression unit, have been accurately modelled with Aspen Plus v14. For each scheme, two cases are studied: a case featuring heat integration with the Air Separation Unit and a case without external heat supply. The independent cycle design variables (pressures, temperatures) are numerically optimized to maximize the net electric plant efficiency. The results indicate that, without external heat integration, the cycle with exhaust gas recompression achieves net electric efficiency considerably higher than the basic cycle (48.2 % vs. 51.3 %). However, the efficiency advantage of the recompressed cycle diminishes in the case with external heat integration (51.5 % vs. 53.3 %). When the external heat is further increased, the efficiency of the two cycles tend to converge to approximately 55 %. Sensitivity analyses are also conducted to assess the impact of the performance of the main components (compressors, turbine, air separation unit, heat exchangers) on the efficiency of the two cycle schemes.

Valves and their internal components operate under continuous friction, wear, and tribological loading during service. These effects become more complex and potentially more severe when valves operate in high-pressure hydrogen environments. This paper presents an analytical review and conceptual framework that integrates tribological behavior with hydrogen embrittlement mechanisms in valve internal components. The study examines contact conditions in valve internals, including seat–disc interfaces and other sliding surfaces. Particular attention is given to contact stress estimation, asperity-level interactions, and realistic friction and wear modeling. Tribological models such as contact mechanics and wear relationships are discussed alongside hydrogen transport and embrittlement mechanisms. The interaction between these processes is analyzed to highlight how hydrogen exposure may modify tribological parameters such as friction coefficient, effective hardness, and crack propagation resistance. The paper further discusses mitigation strategies including material selection, hardfacing alloys, advanced coatings, and surface finishing techniques that improve resistance to hydrogen-assisted tribological degradation. Design considerations aimed at reducing excessive contact stress, minimizing sharp geometric stress concentrators, and optimizing valve seating forces are also addressed. Additionally, lubrication strategies suitable for hydrogen service are briefly examined. Finally, a conceptual quantitative framework is proposed to estimate the relative severity of tribological degradation in valve internals operating under high-pressure hydrogen conditions.

An increasing number of sensors and actuators are being used in today’s high-tech drilling tools to further optimize the drilling process. Each sensor and actuator either generates data that needs to be processed or requires real-time input control signals. RISC-V processors are being developed to meet the computational demands of today’s applications. A known bottleneck for processors is the data flow and instruction input to the processor, especially as memory response times are particularly high for the state-of-the-art harsh environment silicon-on-insulator (SOI) technology. This paper presents a high-performance instruction fetch architecture that achieves a high clock frequency while preserving high instructions per cycle. We evaluate different approaches implementing and propose a design that is able to reach up to 0.8 instruction per cycle (IPC) with a clock frequency of 181 MHz, which is more than twice as high as previous designs in this technology. This design is first tested in isolation an then combined with our current RISC-V processor specially designed to be used in such a harsh environment. This architecture achieves 146.5 million instructions per second (MIPS), which is four times higher than other off the shelf solution synthesized for the same harsh environment technology.

Hydrogen and CO2 pipelines present distinct safety and reliability challenges due to hydrogen embrittlement, high-pressure operation, CO2 decompression behavior, and the potential for brittle or ductile fracture. This study develops an integrated framework combining probabilistic risk analysis, reliability modeling, and life cycle assessment (LCA) to quantify failure likelihoods and environmental impacts across all pipeline life cycle stages. A comparative evaluation of hydrogen and CO2 transport highlights differences in dominant failure modes, release behavior, and consequence severity. Results indicate that material grade selection, operating pressure, inspection intervals, and leak detection capability are the most influential parameters affecting life cycle reliability and greenhouse gas impacts. The proposed framework provides practical guidance for improving pipeline design, operation, and regulatory decision-making in emerging low-carbon energy systems.

Identifying the root cause of an anomaly among hundreds of sensors is critical for preventing safety incidents and costly downtime in complex monitored systems. Existing studies evaluate root cause analysis (RCA) methods using top@k accuracy. We show that this metric has a fundamental blind spot: it conflates two failure modes, retrieval failure, where the true cause is never considered, and reranking failure, where it is considered but ranked too low. In this work, we introduce a retrieval-reranking decomposition and audit four well-known benchmarks to expose this blind spot. Our experiments show that, on benchmarks with complex faults, statistical baselines mis-rank the true cause 79-100