97 research outputs found
Note on Divergence of the Chapman-Enskog Expansion for Solving Boltzmann Equation
Within about a year (1916-1917) Chapman and Enskog independently proposed an
important expansion for solving the Boltzmann equation. However, the expansion
is divergent or indeterminant in the case of relaxation time .
Even since this divergence problem has puzzled this subject for a century. By
using a modified M\"obius series inversion formula, this paper proposes a
modified Chapman-Enskog expansion with a variable upper limit of the summation.
The new expansion can give not only a convergent summation but also provide the
best-so-far explanation on some unbelievable scenarios occurred in previous
practice.Comment: 4 pages, 0 figures, 2 table
ChatLaw: Open-Source Legal Large Language Model with Integrated External Knowledge Bases
Large Language Models (LLMs) have shown the potential to revolutionize
natural language processing tasks in various domains, sparking great interest
in vertical-specific large models. However, unlike proprietary models such as
BloombergGPT and FinGPT, which have leveraged their unique data accumulations
to make strides in the finance domain, there hasn't not many similar large
language models in the Chinese legal domain to facilitate its digital
transformation.
In this paper, we propose an open-source legal large language model named
ChatLaw. Due to the importance of data quality, we carefully designed a legal
domain fine-tuning dataset. Additionally, to overcome the problem of model
hallucinations in legal data screening during reference data retrieval, we
introduce a method that combines vector database retrieval with keyword
retrieval to effectively reduce the inaccuracy of relying solely on vector
database retrieval. Furthermore, we propose a self-attention method to enhance
the ability of large models to overcome errors present in reference data,
further optimizing the issue of model hallucinations at the model level and
improving the problem-solving capabilities of large models. We also
open-sourced our model and part of the data at
https://github.com/PKU-YuanGroup/ChatLaw
Binder-Free Nickel Oxide Lamellar Layer Anchored CoO Nanoparticles on Nickel Foam for Supercapacitor Electrodes
To enhance the connection of electroactive materials/current collector and accelerate the transport efficiency of the electrons, a binder-free electrode composed of nickel oxide anchored CoO nanoparticles on modified commercial nickel foam (NF) was developed. The nickel oxide layer with lamellar structure which supplied skeleton to load CoO_{x) electroactive materials directly grew on the NF surface, leading to a tight connection between the current collector and electroactive materials. The fabricated electrode exhibits a specific capacitance of 475 F/g at 1 mA/cm. A high capacitance retention of 96% after 3000 cycles is achieved, attributed to the binding improvement at the current collector/electroactive materials interface. Moreover, an asymmetric supercapacitor with an operating voltage window of 1.4 V was assembled using oxidized NF anchored with cobalt oxide as the cathode and activated stainless steel wire mesh as the anode. The device achieves a maximum energy density of 2.43 Wh/kg and power density of 0.18 kW/kg, respectively. The modified NF substrate conducted by a facile and effective electrolysis process, which also could be applied to deposit other electroactive materials for the energy storage device
Optimization of \u3b2-carotene production by a newly isolated Serratia marcescens strain
Abstract \u3b2-carotene is a commonly used food colorant. In this
work, a novel \u3b2-carotene producing strain, Serratia marcescens
RB3, was isolated and identified by physiological and biochemical
tests, as well as 16S rDNA sequence analysis. The production of
\u3b2-carotene by S. marcescens RB3 was identified through HPLC
analysis. The cultivation conditions for \u3b2-carotene production by
S. marcescens RB3 were optimized as 2.0% lactose, 2.0% peptone, 0.3%
beef extract, 1.0% NaCl supplemented with 0.05% Fe2+, pH 6.0 and
30\ubaC. Under the optimal conditions, the yield of \u3b2-carotene
achieved 2.45 \u3bcg/mL
Efficient capacity enhancement using OFDM with interleaved subcarrier number modulation in bandlimited UOWC systems
We propose and demonstrate an efficient capacity enhancement scheme for bandlimited underwater optical wireless communication (UOWC) systems by utilizing orthogonal frequency division multiplexing with interleaved subcarrier number modulation (OFDM-ISNM). In the proposed OFDM-ISNM, joint number and constellation mapping/de-mapping is utilized to avoid error propagation and subblock interleaving is further applied to address the low-pass effect of the bandlimited UOWC system. The feasibility and superiority of the proposed OFDM-ISNM scheme for practical bandlimited UOWC systems have been verified through both simulations and experiments. The obtained results demonstrate that the proposed OFDM-ISNM scheme is capable of efficiently improving the achievable data rate of the bandlimited UOWC system. Specifically, the experimental results show a significant 28.6% capacity enhancement by OFDM-ISNM over other benchmark schemes, achieving a data rate of 3.6 Gbps through a 2-m water channel
Climate change impacts on precipitation and water resources in Northwestern China
A statistical analysis is conducted on the hourly precipitation at 105 national meteorological stations in the Xinjiang region of China from 2011 to 2020. The purpose of this analysis is to determine the total quantity of precipitation during the warm and cold seasons, as well as the precipitation frequency at each station. The results of the analysis indicate that there is a more pronounced inter-annual variation in precipitation during the warm and cold seasons in Xinjiang, where the total amount of precipitation during the warm season is significantly higher than that during the cold season, with the warm season experiencing at least twice as much precipitation. In terms of the inter-annual incremental amount of precipitation, both the warm and cold seasons exhibit a trend of increasing and then decreasing over the years. However, the curvature change is more prominent in the cold season compared to the warm season, suggesting that the inter-annual variation in precipitation during the warm season remains relatively stable. The spatial distribution characteristics of the total precipitation in Xinjiang indicate that warm-season precipitation is more scattered, while cold-season precipitation is mainly concentrated in the northern region of the territory. This pattern holds true at low, medium, medium–high, and high altitudes. The cumulative precipitation during the warm season is always higher than that in the cold season, and this difference becomes more prominent with increasing altitude. This indicates that warm-season precipitation in Xinjiang is closely related to its complex topographic structure, particularly the convective weather generated by topographic clouds. On the other hand, precipitation in the cold season is mainly concentrated in the low- and medium-altitude stations, and there is not much correlation between precipitation and altitude. Precipitation is mainly affected by the mesoscale and the direct influence of large-scale weather systems. Analysis of precipitation in extreme moments reveals that during the warm season, extreme precipitation events occur mainly from the evening to early morning (19:00–03:00 the next day), accounting for 75.24% of the 105 stations. In contrast, during the cold season, extreme precipitation events occur between 03:00 and 18:00, corresponding to 74.29% of the stations. The relationship between precipitation and altitude differs in the warm and cold seasons. In the warm season, there is a linear relationship between precipitation and altitude, with a slope of 0.72 and a correlation coefficient of 0.52, indicating that precipitation increases with increasing altitude. However, in the cold season, the linear relationship between precipitation and altitude is very inconspicuous, with a slope of −0.05 and a correlation coefficient of −0.05, suggesting that there is no significant relationship between precipitation and altitude during this season. These findings provide valuable insights into the changing patterns of precipitation gradients at different altitudes and seasons in Xinjiang. This information can be used for the site selection of smokestack operations in high-altitude areas and for ground and air weather modification operations in low-altitude areas. Additionally, these data contribute to the understanding of precipitation patterns in Xinjiang, further improving the effectiveness of weather modification efforts and increasing the utilization of airborne water resources
Original Article One stage laminoplasty and posterior herniotomy for the treatment of myelopathy caused by cervical stenosis with cervical disc herniation
Abstract: The aim of the study was to introduce a method of one stage laminoplasty and posterior herniotomy for myelopathy caused by cervical stenosis with cervical disc herniation and to evaluate the clinical efficacy of this surgery. From 1999 to 2008, 18 patients with myelopathy caused by cervical stenosis with cervical disc herniation who underwent this procedure were included. The average age was 63 years (range 48-74 years), and the average follow-up period was 46 months (range 3-108 months). Neurologic status was evaluated using the JOA scoring system. Neurological symptoms improvement was seen in all patients after surgery. The average JOA score was 14.22±1.86 by final follow-up, which was higher than preoperative values (P<0.01), and the average improvement in neurological function was 76.63%. Neurologic examination showed that excellent results had been obtained by 10 patients, good results by 8 patients, with no fair or poor results. 2 patients developed cerebrospinal fluid leakage after surgery and recovered during the follow-up period. One patient with cervical disc herniation developed postoperative C5 palsy on the axle side on the third day after surgery. She completely recovered by 1 month after surgery. No other patients experienced postoperative neurologic complications. Complete anterior and posterior decompression of the spinal cord was achieved after surgery. We concluded that one stage laminoplasty and posterior herniotomy is an effective, reliable, and safe procedure for the treatment of myelopathy caused by cervical stenosis with cervical disc herniation
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Brake wear induced PM10 emissions during the world harmonised light-duty vehicle test procedure-brake cycle
In this work, the particulate matter less than 10 μm (PM10) emissions from a medium-sized passenger vehicle's front brake wear were studied using a finite element analysis (FEA) and experimental approaches. The world harmonised light-duty vehicle test procedure-brake (WLTP-B) cycle was chosen to simulate real-world driving. An electrical low-pressure impactor (ELPI+) was used to count the brake wear particles on a brake dynamometer sealed in a chamber. In addition, a machine learning method, namely, extreme gradient boosting (XGBoost), was employed to capture the feature importance rankings of braking conditions contributing to brake wear PM10 emissions. The simulated PM10 emissions were quite consistent with the measured ones, with an overall relative error of 9%, indicating that the proposed simulation approach is promising to predict brake wear PM10 during the WLTP-B cycle. The simulated and experimental PM10 emission factors during the WLTP-B cycle were 6.4 mg km−1 veh−1 and 7.0 mg km−1 veh−1, respectively. Among the 10 trips of the WLTP-B cycle, the measured PM10 of trip #10 was the largest contributor, accounting for 49% of total PM10 emissions. On the other hand, the XGBoost results revealed that the top five most important factors governing brake wear PM10 emissions were dissipation energy, initial braking speed, final rotor temperature, braking power, and deceleration rate. From the perspective of friendly driving behaviour and regulation, limiting severe braking and high-speed braking has the potential to reduce PM10 emissions from brake wear
Verification of Land-Atmosphere Coupling in Forecast Models, Reanalyses and Land Surface Models Using Flux Site Observations
We confront four model systems in three configurations (LSM, LSM+GCM, and reanalysis) with global flux tower observations to validate states, surface fluxes, and coupling indices between land and atmosphere. Models clearly under-represent the feedback of surface fluxes on boundary layer properties (the atmospheric leg of land-atmosphere coupling), and may over-represent the connection between soil moisture and surface fluxes (the terrestrial leg). Models generally under-represent spatial and temporal variability relative to observations, which is at least partially an artifact of the differences in spatial scale between model grid boxes and flux tower footprints. All models bias high in near-surface humidity and downward shortwave radiation, struggle to represent precipitation accurately, and show serious problems in reproducing surface albedos. These errors create challenges for models to partition surface energy properly and errors are traceable through the surface energy and water cycles. The spatial distribution of the amplitude and phase of annual cycles (first harmonic) are generally well reproduced, but the biases in means tend to reflect in these amplitudes. Interannual variability is also a challenge for models to reproduce. Our analysis illuminates targets for coupled land-atmosphere model development, as well as the value of long-term globally-distributed observational monitoring
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