Allowed Spatial Transitions and Cancellation of the Richard­son-Langmuir Ban

The ancient emission formulas of Langmuir and Richardson entered the calculations of subtle effects in semiconductor devices as basic ones.But,in the physics of semiconductor devices,these models have long played a purely decorative role,since they can describe in the most rough approximation only individual sections of the I-V characteristic.But it is precisely the fact that these formulas are basic when describing the barrier current-voltage characteristics(CVC)and prevented the consideration and use of thermoelectric effects in materials on a nano-scale.Thus,as these basic emission models actually imposed a ban on the MEASURABILITY of local thermoelectric effects,the existence of which has already been proven both phenomenologically and experimentally.The quantum transition technique is based on classical models.But it can also be used to correct these classic formulas.The calculation of the spatial transition of electrons over the potential barrier,taking into account the polarity of the kinetic energy,gives currents that are significantly higher than the currents of Langmuir and Richardson,including in the initial section of the I-V characteristic.Moreover,ballistic currents are concentrated at energy levels close to the threshold.This effect of condensation of electrons flowing down the barrier transforms the"anomalous"Seebeck coefficients into normal MEASURABLE Local Thermal EMF,including in p-n junctions.

Construction of Characteristic Towns in Suburban Areas

The policy background of the construction of characteristic towns in China and the spatial characteristics of suburban towns were studied.The opportunities and challenges of the construction of characteristic towns in the suburbs under the background of new urbanization were discussed.And appropriate planning strategy for the construction of characteristic towns in the suburbs was explored.

A tour-based analysis of travel mode choice accounting for regional transit service

The aim of this work is to explore the impact of regional transit service on tour-based commuter travel behavior by using the Bayesian hierarchical multinomial logit model, accounting for the spatial heterogeneity of the people living in the same area.With two indicators, accessibility and connectivity measured at the zone level, the regional transit service is captured and then related to the travel mode choice behavior. The sample data are selected from Washington-Baltimore Household Travel Survey in 2007,including all the trips from home to workplace in morning hours in Baltimore city. Traditional multinomial logit model using Bayesian approach is also estimated. A comparison of the two different models shows that ignoring the spatial context can lead to a misspecification of the effects of the regional transit service on travel behavior. The results reveal that improving transit service at regional level can be effective in reducing auto use for commuters after controlling for socio-demographics and travel-related factors.This work provides insights for interpreting tour-based commuter travel behavior by using recently developed methodological approaches. The results of this work will be helpful for engineers, urban planners, and transit operators to decide the needs to improve regional transit service and spatial location efficiently.

Nanoengineering of Flux Pinning Sites in High-T_c Superconductors

Volume pinning forces were determined for a variety of bulk high-Tc superconductors of the 123-type from magnetization measurements. By means of scaling of the pinning forces, the acting pinning mechanisms in various temperature ranges were identified. The Nd-based superconductors and some YBCO crystals exhibited a dominating pinning of the δTc-type (i.e. , small, superconducting pinning sites). In contrast to this, the addition of insulating 211 particles provided pinning of the δ/-type; providing effective pinning in the entire temperature range acting as a 'background' pinning mechanism for the peak effect. Due to the small coherence lengths of the high-Tc compounds, effective pinning sites are defects or particles of nanometer size relative to ζ3. Integral magnetic measurements of the magnetization as a function of temperature in large applied magnetic fields (up to 7 T) revealed that practically all high-Tc compounds were spatially inhomogeneous, which could be caused by oxygen deficiency (YBCO), solid solutions of Nd/Ba (NdBCO and other light rare earth compounds), intergrowths (Bi-based superconductors), and doping by pair-breaking dopants like Zn, Pr. This implies that the superconducting sample consists of stronger and weaker superconducting areas, coupled together. In large applied fields, this coupling gets broken and the magnetization versus temperature curves revealed more than one superconducting transition. In contrast, irradiation experiments by neutrons, protons, and heavy-ions enabled the artificial introduction of very effective pinning sites into the high-Tc superconductors, thus creating a large variety of different observations using magnetic data. From all these observations, we construct a pinning diagram for bulk high-Tc superconductors explaining many features observed in high-Tc samples.