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This brief presents a comprehensive analysis of the output-dependent modulation (ODM) in a current-steering digital-to-analog converter (CS-DAC) based on the differential-quad switching (DQS) structure. A mathematical model is proposed to accurately describe ODM, which is categorized into two types: output transition errors and boundary effect errors. A novel approach of adding isolation devices is introduced and reinterpreted to mitigate the effect of ODM. The simulation results indicate that the inclusion of isolation devices efficiently suppresses the odd harmonics at mid-to-high frequency by a value that is 13 dB lower than before. Experimental validation is conducted on a 16-bit 250 MS/s CS-DAC fabricated in a 180 nm process. [ABSTRACT FROM AUTHOR]

Both surface motion and hole stress concentration have always been concerned in engineering design. In this paper, a theoretical approach is used to study the scattering problem of circular cavities under a non-symmetrical V-shaped canyon. The wave displacement function is obtained by solving the Helmholtz equation that meets the zero-stress boundary conditions by adopting the method of separation of variables and the symmetric method. Based on the complex function method, multi-polar coordinate method and region-matching technique, algebraic equations are established at relevant conditions, which include auxiliary and free boundary conditions. Then, according to sample statistics, a least-square method is used instead of the Fourier expansion method to solve the undetermined coefficients of the algebraic equations by discrete boundary. Numerical results show that the theoretical method is verified valid by the finite element method and the reduced model, and the displacement of the free surface and the stress of the circular cavity are related to the shape of the canyon, the position of the circular cavity, the direction of the incident wave and the frequency content of the excitation. [ABSTRACT FROM AUTHOR]

The torsional vibrations of traction drive shafting system of EMU is one of key factors on heavily influence the running smoothness,safety and reliability of high-speed train. The torsional vibrations of a typical traction drive shafting system of EMU are investigated. After a concise introduction,the traction drive shafting system is simplified and equivalent to a lumped-parameters model with five moment of inertias and four torsional stiffness coefficients. Then,considering the meshing relationship of driving and driven gears,an undamped free torsional vibration equation of this lumped model is established by using direct stiffness method. At last,the natural frequency and mode shapes of this shafting system are obtained with the help of MATLAB software. On the other hand,a MATLAB/Simulink simulation model is also constructed according to above lumped-parameters model equation. And subsequently,the acceleration and displacement Bode plots of shafting system are calculated from this simulation model,these amplitude-frequency results are very useful to verify the natural frequencies obtained directly from the lumped model equation. Results show that the established lumped mass model is available to simulate the torsional vibration characteristics of traction drive shafting system,and the torsional resonance and fatigue problems may mainly happen on the driving side of shafting system. The research works are very useful for the future study on the dynamic design and optimization of traction drive shafting system of EMU.

Park green spaces (PGSs) are an important component of urban natural carbon sinks, while their spatial morphological patterns can affect the carbon sequestration capacity themselves. This study selected six typical urban parks in the central district of Shanghai and analyzed the correlation between spatial morphological indices and CO2 concentration distribution of the PGSs based on ENVI-met and BRT models. It further explored the interaction mechanisms in the carbon cycling process of urban PGSs under the influence of different spatial morphology. The results shows that urban PGSs play the role of carbon sink in diurnal period, and the difference of CO2 concentration distribution in green space is the largest at 11 a.m. The green biomass (Gb) and arboreal area ratio (Ar) are the most important indices affecting the distribution of carbon concentration. The two indices describing spatial patterns, namely, Cohesion (Co) and canopy density (CanopyD) also significantly impact CO2 concentration. These indices have a positive impact on carbon sinks. The parkway area ratio (Pr) is a disturbing index that also has an obvious negative impact on the distribution of CO2 concentration. The moderate herbs area ratio (Hr) and open land area ratio (Or) are conducive to regulating the microclimate environment and enhancing carbon sink capacity. There is an interactive relationship between spatial indices and microclimate environment indices, as well as physical and physiological indices in the carbon sink process of green areas. The study suggested that in green space management aiming at carbon reduction, combined with the influence threshold of Gb on carbon reduction and paying attention to the importance of green amount on carbon sequestration, the vegetation density and allocation ratio should be rationally distributed to form a park green space landscape with efficient carbon fixation. [ABSTRACT FROM AUTHOR]

A heterogeneous electro-Fenton system with fluffy clump steel wire (FCSW) was described for the degradation of p-nitrophenol (p-NP) in water. The influences of the initial pH, initial concentration of FCSW, applied current density on the p-NP, and total organic carbon (TOC) removal percentages were investigated. Compared with the homogeneous electro-Fenton process, the presence of the FCSW catalyst significantly improved the degradation efficiency, the p-NP removal percentages could reach 94.31% after 60 min under the appropriate operating conditions that initial pH value of 3.0, initial FCSW concentration of 3.0 g/L, current density of 3.0 mA/cm2, and the TOC removal percentages could reach 78.96% after 180 min. Aromatic intermediates and carboxylic acids had been identified by chromatographic techniques, and a plausible reaction pathway for p-NP mineralization by heterogeneous electro-Fenton process with FCSW was proposed. The catalytic reusability of FCSW was ultimately evaluated for the repeated use, and the degradation ratio of p-NP could be maintained steadily at 89–96% during 10 cycles, as well as the minimal variations of its structure and composition. [ABSTRACT FROM AUTHOR]

This study investigated the potential effect of vacuum annealing on the microstructure and hot salt corrosion behavior of CoNiCrAlY/YSZ/LaMgAl11O19 (LMA) double-ceramic coatings. A hot-salt corrosion test revealed that sprayed coatings exhibited an unsatisfactory anti-corrosion performance, and the LMA layer underwent severe fracture and corrosion degradation. Vacuum annealing induced a prominent recrystallization of the amorphous phase in LMA layer, triggering severe volume shrinkage and microcrack initiation. The recrystallization and volume shrinkage of the LMA layer were aggravated by an increase in the annealing temperature. The annealed coating with a higher fraction of the LaMA phase showed superior resistance to hot-salt corrosion. However, the salt mixture diffused simultaneously along the microcracks and eventually eroded into the YSZ layer. These results confirmed that vacuum annealing significantly enhanced the hot-salt corrosion resistance of the LMA layer. However, it deteriorated the barrier effect of the salt mixture through microcrack formation. [ABSTRACT FROM AUTHOR]