Determination and analysis of natural gas vehicle tailpipe emissions based on continuous CVS measurement

Code of Federal Regulations Title 40 (CFR-40) specified a formula for calculating constant Dilution Factor (DF) to account for background pollutants in Constant Volume Sampler (CVS) emissions measurement system. However, it is recognized that the DF is dynamically changing due to the CVS mechanism. Based on the continuous measurement data obtained from natural gas vehicle emissions testing, a new approach was used in this study to calculate instantaneous DF of the CVS system during the test cycle. Using the instantaneous DF improves the accuracy of mass emission measurements, especially when the exhaust pollutant concentrations were approaching that in the ambient background air. The instantaneous DF was also used to recover the emissions concentrations in the raw engine exhaust prior to being diluted. In this study, vehicle tailpipe emissions characteristics at different engine operation modes were analyzed for different natural gas engines and measures for reducing emissions were also discussed

Learnable Reconstruction Methods from RGB Images to Hyperspectral Imaging: A Survey

Hyperspectral imaging enables versatile applications due to its competence in capturing abundant spatial and spectral information, which are crucial for identifying substances. However, the devices for acquiring hyperspectral images are expensive and complicated. Therefore, many alternative spectral imaging methods have been proposed by directly reconstructing the hyperspectral information from lower-cost, more available RGB images. We present a thorough investigation of these state-of-the-art spectral reconstruction methods from the widespread RGB images. A systematic study and comparison of more than 25 methods has revealed that most of the data-driven deep learning methods are superior to prior-based methods in terms of reconstruction accuracy and quality despite lower speeds. This comprehensive review can serve as a fruitful reference source for peer researchers, thus further inspiring future development directions in related domains

Genetic analysis of baculovirus resistance in lepidopteran model insect Bombyx mori L.

In order to clarify the resistant mechanism of BmNPV in silkworm, and from negative to prove agricultural pest inheritance of virus resistance, in this study, we used the highly resistant strain NB and susceptible strain 306 as the material through the method of classical genetics experiment, and proved that the baculovirus resistance in silkworm is controlled by a pair of autosomal dominant major gene. At the same time, we used random amplification of polymorphic DNA (RAPD) random primers to screen a molecular marker which are in high linkage with the resistant trait. Validity of the molecular marker was proved in BC1, F2 populations, which further demonstrated that the baculovirus resistance in silkworm is controlled by a pair of autosomal dominant major gene. This can provide an effective research basis for the emergence of baculovirus resistance in pest and its resistant mechanism.Key words: Bombyx mori, molecular markers, genetic analysis, biological control, baculovirus resistance

The influence of 1-MCP on the fruit quality and flesh browning of ‘Red Fuji’ apple after long-term cold storage

This study assessed the influence of 1-MCP treatment on the fruit quality and flesh browning of ‘Red Fuji’ apple at shelf life after long-term cold storage. The ‘Red Fuji’ fruit were stored at 0±0.5 °C for 270 days after treating with 1.0 μL L-1 1-methylcyclopropylene (1-MCP). Fruit quality, browning rate of stem-end flesh, chlorogenic acid content, polyphenol oxidase (PPO) activity were analyzed at shelf-life under 20±0.5 °C, the expression profile of ethylene receptors (MdERS1), phenylalnine ammonia lyase genes (MdPA L1, MdPA L2), quinate hydroxycinnamoyl/hydrxycinnamoyl CoA shi-kimate gene (MdHCT3), polyphenol oxidase genes (MdPPO1, MdPPO5)and lipoxygenase gene (MdLOX) were measured by real-time quantitative PCR. 1-MCP treatment improved the fruit storage quality, decreased stem-end flesh tissue browning, and fruit decay. In addition, the fruit respiration rate and ethylene production rate increased at shelf-life, but this increase could be inhibited by 1-MCP. The same rule was observed in the changes of chlorogenic acid content and PPO activity, the expression of MdERS1, MdPA L1, MdPPO1 and MdLOX were inhibited by 1-MCP as well in the stem-end flesh. Thus, 1-MCP treatment improves the fruit quality of ‘Red Fuji’ apple at shelf-life after long-term cold storage, and inhibits the browning of stem-end flesh by decreasing the chlorogenic acid content and PPO activity. MdPA L1, MdHCT3, MdPPO1 and MdLOX participate in the flesh browning progress

Experimental study on the dynamic threshold pressure gradient of high water-bearing tight sandstone gas reservoir

Tight sandstone water-bearing gas reservoirs typically exhibit low porosity and low permeability, with reservoir rocks characterized by complex pore structures, often featuring micron-scale or smaller pore throats. This intricate reservoir structure significantly restricts fluid flow within the reservoir, necessitating a certain threshold pressure gradient (TPG) to be overcome before flow can commence. This study focuses on the Ordos Basin and explores the influence of high water content tight sandstone gas reservoirs on TPG under different water saturation and formation pressure conditions through experiments. A mathematical model of TPG is established using multiple linear regression method. The results show that TPG is primarily affected by water saturation, followed by formation pressure. As the water saturation increases, the TPG of the core decreases, and the change becomes more pronounced when the water saturation exceeds 50%. As formation pressure increases, the weakening of the slippage effect in gas molecules leads to TPG stabilization, especially when local pressure exceeds 25.0 MPa. The research also shows that low-permeability cores exhibit greater TPG variation with pressure changes, while high-permeability cores remain more stable. A mathematical model was developed and validated to predict TPG based on permeability, water saturation, and formation pressure. These findings highlight the need to monitor formation water content during tight sandstone gas reservoir development to optimize production strategies, providing valuable insights for improving reservoir management and guiding future research

How Do Your Code LLMs Perform? Empowering Code Instruction Tuning with High-Quality Data

Recently, there has been a growing interest in studying how to construct better code instruction tuning data. However, we observe Code models trained with these datasets exhibit high performance on HumanEval but perform worse on other benchmarks such as LiveCodeBench. Upon further investigation, we find that many datasets suffer from severe data leakage. After cleaning up most of the leaked data, some well-known high-quality datasets perform poorly. This discovery reveals a new challenge: identifying which dataset genuinely qualify as high-quality code instruction data. To address this, we propose an efficient code data pruning strategy for selecting good samples. Our approach is based on three dimensions: instruction complexity, response quality, and instruction diversity. Based on our selected data, we present XCoder, a family of models finetuned from LLaMA3. Our experiments show XCoder achieves new state-of-the-art performance using fewer training data, which verify the effectiveness of our data strategy. Moreover, we perform a comprehensive analysis on the data composition and find existing code datasets have different characteristics according to their construction methods, which provide new insights for future code LLMs. Our models and dataset are released in https://github.com/banksy23/XCoderWorking in progres

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Influence of Interaction between Microcracks and Macrocracks on Crack Propagation of Asphalt Concrete

This paper aims to reveal the interaction relationship between microcracks and macrocracks and the influence of the interaction on the crack propagation behavior. A theoretical model of asphalt concrete was established for the interaction between microcracks with different crack densities and a macrocrack. And a meso-structure model of AC-13 dense-graded asphalt concrete was established by combining the Talyor medium method and the DEM (discrete element method). Macro and micro parameters, such as the stress–strain characteristics, crack evolution parameters, and crack tip stress field, were obtained through a semi-circular bend virtual test and used to study the characteristics of crack propagation under the interaction between microcracks and the macrocrack. The results indicate that the interaction has an effect throughout the process of asphalt concrete damage, and shows shielding and acceleration effects as the microcrack density changes. When the microcrack density is low (f3 ≤ 0.8), the crack propagation process, which is affected by the interaction effect, exhibits significant differences, and the interaction effect shows the shielding effect. When the microcrack density is high (f3 > 0.8), the fracture stage is mainly affected by the interaction effect, which shows the acceleration effect. The results provide a predictive theoretical and numerical model for low-temperature cracking of asphalt pavement, and theoretical support for the design, maintenance, and upkeep of long-life pavement