75 research outputs found

    Comparative Analysis on Energy Consumption of Commercial Buildings Based on Sub-metered Data

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    With energy use growing rapidly around the world, building energy conservation is becoming a great concern especially for large commercial buildings. Therefore, it is of great significance to develop appropriate methods for energy use assessment of commercial buildings. In recent years, energy monitoring system (EMS) has been applied in some large-scale commercial buildings, which has laid the foundation for exhaustive and authentic evaluation. However, most of the current studies are only focused on annual or monthly aggregated energy consumption. Though end-use data are monitored in some buildings, only major categories or equipment are included. Little has been done to analyze the energy performance of numerous buildings with detailed hourly end-use data. With the access to hourly sub-metered data of detailed end uses, this study aims to introduce a comparing method to evaluate building energy performance through a case study. Information on selected buildings in the case was introduced. The research intends to compare energy use intensity (EUI) of the 19 malls based on a uniform energy data model, from total energy to detailed end-uses. It was shown that there is a significant discrepancy on the total energy use among these buildings, mainly due to HVAC (Heating, Ventilation and Air Conditioning) and public lighting. Then an in-depth comparative study was conducted on the energy consumption of public lighting and HVAC respectively. An unexpectedly remarkable discrepancy was illustrated on the EUI of public lighting. Thus the daily and hourly energy of public lighting were compared to identify the discrepancy in management mode. The study on HVAC was focused on the comparison of daily and hourly EUI in terms of four subordinate end uses (chillers, chilled water pumps, fans and cooling systems). The result showed that chillers accounts for larger proportions of total energy use, and the daily and hourly data were compared between buildings with similar climate. At last, the methods were summarized and challenges were discussed

    Learning to In-paint: Domain Adaptive Shape Completion for 3D Organ Segmentation

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    We aim at incorporating explicit shape information into current 3D organ segmentation models. Different from previous works, we formulate shape learning as an in-painting task, which is named Masked Label Mask Modeling (MLM). Through MLM, learnable mask tokens are fed into transformer blocks to complete the label mask of organ. To transfer MLM shape knowledge to target, we further propose a novel shape-aware self-distillation with both in-painting reconstruction loss and pseudo loss. Extensive experiments on five public organ segmentation datasets show consistent improvements over prior arts with at least 1.2 points gain in the Dice score, demonstrating the effectiveness of our method in challenging unsupervised domain adaptation scenarios including: (1) In-domain organ segmentation; (2) Unseen domain segmentation and (3) Unseen organ segmentation. We hope this work will advance shape analysis and geometric learning in medical imaging

    Data-Centric Diet: Effective Multi-center Dataset Pruning for Medical Image Segmentation

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    This paper seeks to address the dense labeling problems where a significant fraction of the dataset can be pruned without sacrificing much accuracy. We observe that, on standard medical image segmentation benchmarks, the loss gradient norm-based metrics of individual training examples applied in image classification fail to identify the important samples. To address this issue, we propose a data pruning method by taking into consideration the training dynamics on target regions using Dynamic Average Dice (DAD) score. To the best of our knowledge, we are among the first to address the data importance in dense labeling tasks in the field of medical image analysis, making the following contributions: (1) investigating the underlying causes with rigorous empirical analysis, and (2) determining effective data pruning approach in dense labeling problems. Our solution can be used as a strong yet simple baseline to select important examples for medical image segmentation with combined data sources.Comment: Accepted by ICML workshops 202

    Kinematic analysis and process optimization of root-cutting systems in field harvesting of garlic based on computer simulation technology

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    IntroductionRoot cutting is an important process in garlic field harvesting but is the weakest link in the full mechanization of garlic production. To improve the current situation of technological backwardness and poor operational quality of mechanized garlic root-cutting in the main garlic-producing regions of China, this study combined the physical characteristics and agronomic requirements of garlic plants, and proposed an innovative floating root-cutting technology for garlic combine harvesters that enables the top alignment of bulb, adaptive profiling floating of cutter, and embedded cutting of roots.MethodsThrough the kinematic analysis of the floating cutting process, the coordinate equations of the initial contact point of the bulb, the mathematical model of the floating displacement of the cutting component. Using computer simulation techniques, the dynamic simulation study of the floating cutting process was carried out in the rigid-flexible coupling numerical simulation model of root-cutting mechanism and garlic plant. The influence law of garlic conveying speed, extension spring preload force and stiffness on the floating displacement of the cutting component and the angular velocity of swing arm reset and its formation causes were analyzed by a single-factor simulation test. The key operating parameters of the root-cutting mechanism were optimized through the computerized virtual orthogonal test and fuzzy comprehensive evaluation.Results and discussionThe significance of the factors affecting the floating cutting performance decreased in the following order: extension spring preload force, garlic conveying speed and extension spring stiffness. The optimal parameter combination of the root cutting mechanism obtained from the optimization were as follow: extension spring preload force was 16 N, garlic conveying speed was 0.8 m/s, and extension spring stiffness was 215 N/m. Tests conducted with the optimal parameter combination yielded a root excision rate of 92.72%, which meets the requirements of Chinese garlic field harvesting quality. This study provides computer simulation optimization methods for the optimal design of the root-cutting mechanism, and also provides technical and equipment support for the full mechanization of garlic production in China

    Nicotinic acid changes rumen fermentation and apparent nutrient digestibility by regulating rumen microbiota in Xiangzhong black cattle

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    Objective The aim of this study was to investigate the impact of dietary nicotinic acid (NA) on apparent nutrient digestibility, rumen fermentation, and rumen microbiota in uncastrated Xiangzhong black cattle. Methods Twenty-one uncastrated Xiangzhong black cattle (385.08±15.20 kg) aged 1.5 years were randomly assigned to the control group (CL, 0 mg/kg NA in concentrate diet), NA1 group (800 mg/kg NA in concentrate diet) and NA2 group (1,200 mg/kg NA in concentrate diet). All animals were fed a 60% concentrate diet and 40% dried rice straw for a 120-day feeding experiment. Results Supplemental NA not only enhanced the apparent nutrient digestibility of acid detergent fiber (p<0.01), but also elevated the rumen acetate and total volatile fatty acid concentrations (p<0.05). 16S rRNA gene sequencing analysis of rumen microbiota revealed that dietary NA changed the diversity of rumen microbiota (p<0.05) and the abundance of bacterial taxa in the rumen. The relative abundances of eight Erysipelotrichales taxa, five Ruminococcaceae taxa, and five Sphaerochaetales taxa were decreased by dietary NA (p< 0.05). However, the relative abundances of two taxa belonging to Roseburia faecis were increased by supplemental 800 mg/kg NA, and the abundances of seven Prevotella taxa, three Paraprevotellaceae taxa, three Bifidobacteriaceae taxa, and two operational taxonomic units annotated to Fibrobacter succinogenes were increased by 1,200 mg/kg NA in diets. Furthermore, the correlation analysis found significant correlations between the concentrations of volatile fatty acids in the rumen and the abundances of bacterial taxa, especially Prevotella. Conclusion The results from this study suggest that dietary NA plays an important role in regulating apparent digestibility of acid detergent fiber, acetate, total volatile fatty acid concentrations, and the composition of rumen microbiota

    Effects of NH3 and alkaline metals on the formation of particulate sulfate and nitrate in wintertime Beijing

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    Sulfate and nitrate from secondary reactions remain as the most abundant inorganic species in atmospheric particle matter (PM). Their formation is initiated by oxidation (either in gas phase or particle phase), followed by neutralization reaction primarily by NH3, or by other alkaline species such as alkaline metal ions if available. The different roles of NH3 and metal ions in neutralizing H2SO4 or HNO3, however, are seldom investigated. Here we conducted semi-continuous measurements of SO4 2−, NO3 −, NH4 +, and their gaseous precursors, as well as alkaline metal ions (Na+, K+, Ca2+, and Mg2+) in wintertime Beijing. Analysis of aerosol acidity (estimated from a thermodynamic model) indicated that preferable sulfate formation was related to low pH conditions, while high pH conditions promote nitrate formation. Data in different mass fraction ranges of alkaline metal ions showed that in some ranges the role of NH3 was replaced by alkaline metal ions in the neutralization reaction of H2SO4 and HNO3 to form particulate SO4 2− and NO3 −. The relationships between mass fractions of SO4 2− and NO3 − in those ranges of different alkaline metal ion content also suggested that alkaline metal ions participate in the competing neutralization reaction of sulfate and nitrate. The implication of the current study is that in some regions the chemistry to incorporate sulfur and nitrogen into particle phase might be largely affected by desert/fugitive dust and sea salt, besides NH3. This implication is particularly relevant in coastal China and those areas with strong influence of dust storm in the North China Plain (NCP), both of which host a number of megacities with deteriorating air quality
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