Ching-Chien Huang

The performance of NdFeB permanent magnets is governed by the chemistry and continuity of their grain boundary phases, yet conventional copper modification often suffers from uncontrolled segregation that degrades coercivity. This study establishes a thermochemical coating strategy that enables precise regulation of copper surface diffusion through a combination of powder pretreatment and temperature-controlled heat processing. Vacuum pretreatment of commercially obtained copper citrate powder enhances its reactivity and produces a twofold increase in diffusion depth relative to untreated powder, as verified by glow discharge spectroscopy. Systematic temperature optimization further reveals that treatment at 600 ^∘ C generates the most uniform and effective Cu penetration, driven by liquid-phase-assisted transport above the Nd-Cu eutectic threshold. This optimized diffusion pathway forms a continuous Cu-enriched boundary layer while preventing excessive segregation. Magnetic measurements confirm that the intrinsic magnetic performance, including coercivity (iHc) and maximum energy product ((BH) _max ), is retained after diffusion, demonstrating that microstructural refinement is achieved without compromising the primary magnetic phase. The findings provide a reproducible and scalable pathway for grain boundary engineering in NdFeB magnets and establish an experimentally validated framework for coupling surface diffusion control with magnetic property stabilization.

Street-network configuration influences traffic distribution and delay, but its operational contribution is difficult to separate from urban organization and demand formation in observed cities. This study develops a controlled Parallel Microscopic Simulation (PARAMICS) framework to compare conventional and neo-traditional organization under grid and superblock configurations within a common 240 ha virtual city. A 2 × 2 scenario matrix is used. Population, external access, roadway hierarchy, driver behavior, combined Dynamic Feedback and Stochastic assignment, signal-control procedure, and performance definitions are specified consistently across scenarios, while scenario-specific origin-destination (OD) demand retains the travel-moderation mechanism associated with urban organization. Each scenario is represented by one retained seed-2001 realization; results are therefore descriptive rather than inferential. Stop delay is the archived PARAMICS stop-time measure based on a 7.2 km/h queue-speed threshold and includes low-speed queued movement and complete standstill. The neo-traditional grid produced the lowest average travel time, travel distance, and stop delay, whereas the neo-traditional superblock produced the lowest network-entering vehicular volume. Relative to the conventional grid, the neo-traditional grid showed 14.0% lower network-entering vehicular volume, 3.3% lower average travel time, 3.0% lower average travel distance, and 20.0% lower average stop delay. The network-entry difference is conditional on scenario-specific OD and archived intrazonal treatment and does not represent an equivalent reduction in total vehicle-equivalent input demand. Average stop delay was 22 s higher in each superblock than in the corresponding grid: 30 vs. 52 s under conventional organization and 24 vs. 46 s under neo-traditional organization. Because signalized-intersection count and other implemented network characteristics co-varied with configuration, these are configuration-level contrasts rather than isolated topology effects. Gateway-flow concentration, route overlap, and queue persistence remain mechanism hypotheses rather than directly measured effects. The framework provides a source-traceable engineering basis for evaluating street-network form and access configuration before implementation while explicitly bounding inference to the retained archive.

Street network typology defines the structural envelope within which traffic signal control can operate. Planning‐stage assessments often treat urban form, demand allocation, signal timing, and microsimulation as separate tasks, leaving an unresolved question: whether coordinated signal timing can offset, or only mitigate, the operational disadvantage associated with an unfavorable street layout. This study develops a planning‐stage digital‐twin‐oriented virtual‐city microsimulation framework for evaluating street network typology and coordinated signal control as a coupled infrastructure‐control system. Here, digital‐twin‐oriented virtual‐city microsimulation framework denotes an auditable what‐if workflow based on a controlled virtual representation, not real‐time synchronization, physical‐system mirroring, or closed‐loop operational control. Four typologies, namely, Traditional Grid, Traditional Superblock, Neo‐Traditional Grid, and Neo‐Traditional Superblock, are constructed in a common 240‐ha virtual city under common land use, population, roadway hierarchy, zoning, demand logic, route‐choice treatment, and timing‐generation protocol. Signalized intersections are selected using warrant‐based criteria, coordinated timings are generated with TRANSYT 7F, and the final performance is evaluated in PARAMICS. The results provide deterministic descriptive evidence that structural‐package differences remain after a common timing‐generation protocol. Under both center‐attraction settings, the superblock package produces a 22‐s higher mean stop delay than the corresponding grid package, while reducing the center‐attraction share from 46% to 32% lowers the mean stop delay by 6 s within both structural families. Relative to the Traditional Superblock Network, the Neo‐Traditional Grid Network reduces mean stop delay from 52 to 24 s and total stop delay from 301,184 to 123,552 s, whereas mean travel distance decreases by only 2.8%. The dominant residual penalty of coarse block structure is therefore interruption accumulation rather than geometric route extension. The contribution is a reproducible planning‐stage protocol that converts microsimulation outputs into auditable evidence for topology‐sensitive signal coordination and street‐network design. The findings should be interpreted as deterministic structural‐package contrasts rather than stochastic significance tests, single‐factor causal estimates, or real‐time operational digital‐twin results.