A thermodynamic interpretation of Budyko and L\u27vovich formulations of annual water balance: Proportionality Hypothesis and maximum entropy production

The paper forms part of the search for a thermodynamic explanation for the empirical Budyko Curve, addressing a long-standing research question in hydrology. Here this issue is pursued by invoking the Proportionality Hypothesis underpinning the Soil Conservation Service (SCS) curve number method widely used for estimating direct runoff at the event scale. In this case, the Proportionality Hypothesis posits that the ratio of continuing abstraction to its potential value is equal to the ratio of direct runoff to its potential value. Recently, the validity of the Proportionality Hypothesis has been extended to the partitioning of precipitation into runoff and evaporation at the annual time scale as well. In this case, the Proportionality Hypothesis dictates that the ratio of continuing evaporation to its potential value is equal to the ratio of runoff to its potential value. The Budyko Curve could then be seen as the straightforward outcome of the application of the Proportionality Hypothesis to estimate mean annual water balance. In this paper, we go further and demonstrate that the Proportionality Hypothesis itself can be seen as a result of the application of the thermodynamic principle of Maximum Entropy Production (MEP). In this way, we demonstrate a possible thermodynamic basis for the Proportionality Hypothesis, and consequently for the Budyko Curve. As a further extension, the L\u27vovich formulation for the two-stage partitioning of annual precipitation is also demonstrated to be a result of MEP: one for the competition between soil wetting and fast flow during the first stage; another for the competition between evaporation and base flow during the second stage

Formation and Device Application of Ge Nanowire Heterostructures via Rapid Thermal Annealing

We reviewed the formation of Ge nanowire heterostructure and its field-effect characteristics by a controlled reaction between a single-crystalline Ge nanowire and Ni contact pads using a facile rapid thermal annealing process. Scanning electron microscopy and transmission electron microscopy demonstrated a wide temperature range of 400~500°C to convert the Ge nanowire to a single-crystalline Ni2Ge/Ge/Ni2Ge nanowire heterostructure with atomically sharp interfaces. More importantly, we studied the effect of oxide confinement during the formation of nickel germanides in a Ge nanowire. In contrast to the formation of Ni2Ge/Ge/Ni2Ge nanowire heterostructures, a segment of high-quality epitaxial NiGe was formed between Ni2Ge with the confinement of Al2O3 during annealing. A twisted epitaxial growth mode was observed in both two Ge nanowire heterostructures to accommodate the large lattice mismatch in the NixGe/Ge interface. Moreover, we have demonstrated field-effect transistors using the nickel germanide regions as source/drain contacts to the Ge nanowire channel. Our Ge nanowire transistors have shown a high-performance p-type behavior with a high on/off ratio of 105 and a field-effect hole mobility of 210 cm2/Vs, which showed a significant improvement compared with that from unreacted Ge nanowire transistors

Thermal stability of Mg_2Si_(0.4)Sn_(0.6) in inert gases and atomic-layer-deposited Al_2O_3 thin film as a protective coating

Mg_2Si_(1−x)Sn_x solid solutions are promising thermoelectric materials to be applied in vehicle waste-heat recovery. Their thermal stability issue, however, needs to be addressed before the materials can be applied in practical thermoelectric devices. In this work, we studied the crystal structure and chemical composition of Mg_2Si_(1−x)Sn_x in inert gas atmosphere up to 823 K. We found that the sample was oxidized even in high-purity inert gases. Although no obvious structural change has been found in the slightly oxidized sample, carrier concentration decreased significantly since oxidation creates Mg vacancies in the lattice. We demonstrated that an atomic-layer deposited Al_2O_3 coating can effectively protect Mg_2Si_(1−x)Sn_x from oxidation in inert gases and even in air. In addition, this Al_2O_3 thin film also provides in situ protection to the Sb-doped Mg_2Si_(1−x)Sn_x samples during the laser-flash measurement and therefore eliminates the measurement error that occurs in uncoated samples as a result of sample oxidation and graphite exfoliation issues

Thermal stability of Mg_2Si_(0.4)Sn_(0.6) in inert gases and atomic-layer-deposited Al_2O_3 thin film as a protective coating

Mg_2Si_(1−x)Sn_x solid solutions are promising thermoelectric materials to be applied in vehicle waste-heat recovery. Their thermal stability issue, however, needs to be addressed before the materials can be applied in practical thermoelectric devices. In this work, we studied the crystal structure and chemical composition of Mg_2Si_(1−x)Sn_x in inert gas atmosphere up to 823 K. We found that the sample was oxidized even in high-purity inert gases. Although no obvious structural change has been found in the slightly oxidized sample, carrier concentration decreased significantly since oxidation creates Mg vacancies in the lattice. We demonstrated that an atomic-layer deposited Al_2O_3 coating can effectively protect Mg_2Si_(1−x)Sn_x from oxidation in inert gases and even in air. In addition, this Al_2O_3 thin film also provides in situ protection to the Sb-doped Mg_2Si_(1−x)Sn_x samples during the laser-flash measurement and therefore eliminates the measurement error that occurs in uncoated samples as a result of sample oxidation and graphite exfoliation issues

Straightforward data transfer in a blockwise dataflow for an analog RRAM-based CIM system

Analog resistive random-access memory (RRAM)-based computation-in-memory (CIM) technology is promising for constructing artificial intelligence (AI) with high energy efficiency and excellent scalability. However, the large overhead of analog-to-digital converters (ADCs) is a key limitation. In this work, we propose a novel LINKAGE architecture that eliminates PE-level ADCs and leverages an analog data transfer module to implement inter-array data processing. A blockwise dataflow is further proposed to accelerate convolutional neural networks (CNNs) to speed up compute-intensive layers and solve the unbalanced pipeline problem. To obtain accurate and reliable benchmark results, key component modules, such as straightforward link (SFL) modules and Tile-level ADCs, are designed in standard 28 nm CMOS technology. The evaluation shows that LINKAGE outperforms the conventional ADC/DAC-based architecture with a 2.07×∼11.22× improvement in throughput, 2.45×∼7.00× in energy efficiency, and 22%–51% reduction in the area overhead while maintaining accuracy. Our LINKAGE architecture can achieve 22.9∼24.4 TOPS/W energy efficiency (4b-IN/4b-W) and 1.82 ∼4.53 TOPS throughput with the blockwise method. This work demonstrates a new method for significantly improving the energy efficiency of CIM chips, which can be applied to general CNNs/FCNNs