scholarly journals Assessing the Quality of Convex Approximations for Two-Stage Totally Unimodular Integer Recourse Models

2017 ◽  
Vol 29 (2) ◽  
pp. 211-231 ◽  
Author(s):  
Ward Romeijnders ◽  
David P. Morton ◽  
Maarten H. van der Vlerk
Keyword(s):  
Two Stage ◽  
Convex Approximations ◽  
Integer Recourse

scholarly journals A loose Benders decomposition algorithm for approximating two-stage mixed-integer recourse models

2020 ◽  
Author(s):  
Niels van der Laan ◽  
Ward Romeijnders
Keyword(s):  
Error Bounds ◽  
Benders Decomposition ◽  
Decomposition Algorithm ◽  
Mixed Integer ◽  
Large Problem ◽  
Two Stage ◽  
Convex Approximations ◽  
Integer Recourse ◽  
Benders Decomposition Algorithm ◽  
Problem Instances

Abstract We propose a new class of convex approximations for two-stage mixed-integer recourse models, the so-called generalized alpha-approximations. The advantage of these convex approximations over existing ones is that they are more suitable for efficient computations. Indeed, we construct a loose Benders decomposition algorithm that solves large problem instances in reasonable time. To guarantee the performance of the resulting solution, we derive corresponding error bounds that depend on the total variations of the probability density functions of the random variables in the model. The error bounds converge to zero if these total variations converge to zero. We empirically assess our solution method on several test instances, including the SIZES and SSLP instances from SIPLIB. We show that our method finds near-optimal solutions if the variability of the random parameters in the model is large. Moreover, our method outperforms existing methods in terms of computation time, especially for large problem instances.

MULTISTAGE MICROSTRIP UHF LOAD

2018 ◽  
pp. 53-57 ◽  
Author(s):  
G. G. Savenkov ◽  
V. P. Razinkin ◽  
A. D. Mekhtiev
Keyword(s):  
Frequency Response ◽  
Frequency Band ◽  
High Power ◽  
Two Stage ◽  
High Power Microwave ◽  
Modelling Method ◽  
Optimal Values ◽  
Inductive Elements ◽  
Power Microwave

Applications of modern terminal loads and its relevant disadvantages are described in this paper. The decomposing method of wideband microwave high power microstrip loads design is proposed in this paper with purpose of matching quality improving. Multiple extension of multistage load bandwidth is provided by using of external matching circuit and internal matching inductive elements. The maximum reachable bandwidth of multistage load is estimated and optimal values of mathing circuit elements are founded on basis of equivalent lumped scheme. The topology of microstrip two-stage high power microwave load is developed and its frequency response, calculated via numeric electrodynamic modelling method is outlined in the paper. Modelling results show good matching quality of considered load at the frequency band below 3,5 GHz.

scholarly journals A Comparison of Two-Stage and Traditional Co-Composting of Green Waste and Food Waste Amended with Phosphate Rock and Sawdust

2021 ◽  
Vol 13 (3) ◽  
pp. 1109
Author(s):  
Edgar Ricardo Oviedo-Ocaña ◽  
Angélica María Hernández-Gómez ◽  
Marcos Ríos ◽  
Anauribeth Portela ◽  
Viviana Sánchez-Torres ◽  
...  
Keyword(s):  
Organic Matter ◽  
Product Quality ◽  
Food Waste ◽  
Phosphate Rock ◽  
Pilot Scale ◽  
Two Stage ◽  
Green Waste ◽  
Wet Weight ◽  
Two Phases

The composting of green waste (GW) proceeds slowly due to the presence of slowly degradable compounds in that substrate. The introduction of amendments and bulking materials can improve organic matter degradation and end-product quality. However, additional strategies such as two-stage composting, can deal with the slow degradation of green waste. This paper evaluates the effect of two-stage composting on the process and end-product quality of the co-composting of green waste and food waste amended with sawdust and phosphate rock. A pilot-scale study was developed using two treatments (in triplicate each), one being a two-stage composting and the other being a traditional composting. The two treatments used the same mixture (wet weight): 46% green waste, 19% unprocessed food waste, 18% processed food waste, 13% sawdust, and 4% phosphate rock. The traditional composting observed a higher degradation rate of organic matter during the mesophilic and thermophilic phases and observed thermophilic temperatures were maintained for longer periods during these two phases compared to two-stage composting (i.e., six days). Nonetheless, during the cooling and maturation phases, the two treatments had similar behaviors with regard to temperature, pH, and electrical conductivity, and the end-products resulting from both treatments did not statistically differ. Therefore, from this study, it is concluded that other additional complementary strategies must be evaluated to further improve GW composting.

Evaluation of Drying Performance, Energy Consumption, and Quality of Two-Stage Dried Maize Grain

2021 ◽  
Author(s):  
Md. Akhtaruzzaman ◽  
Md. Hasan Tarek Mondal ◽  
Mrityunjoy Biswas ◽  
Md. Abdul Momin Sheikh ◽  
Anwara Akter Khatun ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Two Stage ◽  
Maize Grain

scholarly journals Quality in Assisted Living: Does It Lie in the Eyes of the Beholder?

2020 ◽  
Vol 4 (Supplement_1) ◽  
pp. 726-727
Author(s):  
Diana White ◽  
Tunalilar Ozcan ◽  
Serena Hasworth ◽  
Jaclyn Winfree
Keyword(s):  
Quality Indicators ◽  
Residential Care ◽  
Assisted Living ◽  
Physical Environment ◽  
Sampling Strategy ◽  
Perceived Quality ◽  
Two Stage ◽  
Regulatory Perspective ◽  
To Receive

Abstract Quality is defined in multiple ways and by different stakeholders (e.g., residents, regulators, informed observers). Using a two-stage stratified sampling strategy, we collected data from N=241 residents living in 31 assisted living and residential care communities (AL/RC) in Oregon. Residents rated their overall satisfaction and satisfaction with the AL/RC as a place to live and to receive care. Each interviewer completed a facility profile summarizing their observations about the setting, including quality of staff-resident interactions and physical environment. Residents and interviewers were also asked whether they would recommend the community to others. Finally, we used deficiency citations given during regular inspections by the licensing agency to proxy regulatory perspective. Results show that perceived quality varied by stakeholder (e.g., residents’ assessments differed from deficiency citations). Given this variation, findings suggest that efforts to make quality indicators publicly available should include multiple measures and perspectives, especially residents.

A novel two-stage method of plant seedlings classification based on deep learning

2021 ◽  
pp. 1-11
Author(s):  
Tianhong Dai ◽  
Shijie Cong ◽  
Jianping Huang ◽  
Yanwen Zhang ◽  
Xinwang Huang ◽  
...  
Keyword(s):  
Deep Learning ◽  
Learning Technology ◽  
Two Stage ◽  
Second Stage ◽  
Stage Classification ◽  
Different Types ◽  
Two Stages ◽  
Plant Seedlings

In agricultural production, weed removal is an important part of crop cultivation, but inevitably, other plants compete with crops for nutrients. Only by identifying and removing weeds can the quality of the harvest be guaranteed. Therefore, the distinction between weeds and crops is particularly important. Recently, deep learning technology has also been applied to the field of botany, and achieved good results. Convolutional neural networks are widely used in deep learning because of their excellent classification effects. The purpose of this article is to find a new method of plant seedling classification. This method includes two stages: image segmentation and image classification. The first stage is to use the improved U-Net to segment the dataset, and the second stage is to use six classification networks to classify the seedlings of the segmented dataset. The dataset used for the experiment contained 12 different types of plants, namely, 3 crops and 9 weeds. The model was evaluated by the multi-class statistical analysis of accuracy, recall, precision, and F1-score. The results show that the two-stage classification method combining the improved U-Net segmentation network and the classification network was more conducive to the classification of plant seedlings, and the classification accuracy reaches 97.7%.

Quality Improvement of Recycled Aggregate Concrete

2006 ◽  
Vol 302-303 ◽  
pp. 308-313 ◽  
Author(s):  
Vivian W.Y. Tam ◽  
X.F. Gao ◽  
C.M. Tam
Keyword(s):  
Compressive Strength ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Two Stage ◽  
New Approach ◽  
Aggregate Concrete ◽  
Strength Based ◽  
Mixing Method ◽  
Strength Variability

The developments of recycled aggregate concrete pressing hard in construction activities; however, the limitations on their applications had never being ended. The focus of this paper is: i) investigating the waste management strategy in construction; ii) proposing the two-stage mixing approach (TSMA) to improve the quality of RAC; and iii) experimenting the TSMA and assessing the benefits possibly gained. It proposes a new approach in mixing concrete, namely, the two-stage mixing method, to improve compressive strength of RAC and lower its strength variability. The replacement ratio from zero to thirty is under experiment on their compressive strength. Based upon the experimental results, improvements of 31 % in strength at 28 days with 30 % RA substitute was achieved. The effect can be attributably to the porous nature of the RA and the pre-mix process which can make some pores filled up resulting in a denser concrete and thus leading to higher strength when compared with the traditional mixing approach. Therefore, two-stage mixing approach can open up a wider application of recycled aggregate concrete.

Sign in / Sign up

Export Citation Format

Share Document