scholarly journals Hygrothermal behaviour of straw bale walls: experimental tests and numerical analyses

2019 ◽  
Vol 4 ◽  
pp. 3
Author(s):  
Alessandra Mesa ◽  
Alberto Arenghi

Straw is an organic material with hygroscopical properties. The high capacity it has of storing moisture from the surroundings can furthermore influence the performance and lead to the possible degradation of the material thereof. The aim of this study was to assess the conductance C-value of a complex material such as straw. A climatic chamber was used to study a sample, which reproduces a traditional plastered straw bale wall. Tests were conducted under different boundary conditions, setting constant values for temperatures and relative humidity. The revision of the assessment's results allowed the calculation of conductance and conductivity values under different conditions. A numerical model was then designed starting from the laboratory data, which was used to characterize material properties. The match between software simulations and laboratory analyses will be a starting point for further tests. Determining the straw conductance C-value is a difficult task to achieve, due to the complexity and the unique properties of the material. In spite of all this, laboratory tests have shown encouraging results, which reflect the great potential of straw as a building material.

2018 ◽  
Author(s):  
Martti-Jaan Miljan ◽  
◽  
Rain Allikmäe ◽  
Andres Jürgenson ◽  
Matis Miljan ◽  
...  

2018 ◽  
Author(s):  
Martti-Jaan Miljan ◽  
◽  
Rain Allikmäe ◽  
Andres Jürgenson ◽  
Matis Miljan ◽  
...  

TAPPI Journal ◽  
2015 ◽  
Vol 14 (2) ◽  
pp. 119-129 ◽  
Author(s):  
VILJAMI MAAKALA ◽  
PASI MIIKKULAINEN

Capacities of the largest new recovery boilers are steadily rising, and there is every reason to expect this trend to continue. However, the furnace designs for these large boilers have not been optimized and, in general, are based on semiheuristic rules and experience with smaller boilers. We present a multiobjective optimization code suitable for diverse optimization tasks and use it to dimension a high-capacity recovery boiler furnace. The objective was to find the furnace dimensions (width, depth, and height) that optimize eight performance criteria while satisfying additional inequality constraints. The optimization procedure was carried out in a fully automatic manner by means of the code, which is based on a genetic algorithm optimization method and a radial basis function network surrogate model. The code was coupled with a recovery boiler furnace computational fluid dynamics model that was used to obtain performance information on the individual furnace designs considered. The optimization code found numerous furnace geometries that deliver better performance than the base design, which was taken as a starting point. We propose one of these as a better design for the high-capacity recovery boiler. In particular, the proposed design reduces the number of liquor particles landing on the walls by 37%, the average carbon monoxide (CO) content at nose level by 81%, and the regions of high CO content at nose level by 78% from the values obtained with the base design. We show that optimizing the furnace design can significantly improve recovery boiler performance.


2021 ◽  
pp. 110706
Author(s):  
Liu Yang ◽  
Jingjing Yang ◽  
Yan Liu ◽  
Yungang An ◽  
Jingheng Chen

Author(s):  
Francesco Braghin ◽  
Federico Cheli ◽  
Edoardo Sabbioni

Individual tire model parameters are traditionally derived from expensive component indoor laboratory tests as a result of an identification procedure minimizing the error with respect to force and slip measurements. These parameters are then transferred to vehicle models used at a design stage to simulate the vehicle handling behavior. A methodology aimed at identifying the Magic Formula-Tyre (MF-Tyre) model coefficients of each individual tire for pure cornering conditions based only on the measurements carried out on board vehicle (vehicle sideslip angle, yaw rate, lateral acceleration, speed and steer angle) during standard handling maneuvers (step-steers) is instead presented in this paper. The resulting tire model thus includes vertical load dependency and implicitly compensates for suspension geometry and compliance (i.e., scaling factors are included into the identified MF coefficients). The global number of tests (indoor and outdoor) needed for characterizing a tire for handling simulation purposes can thus be reduced. The proposed methodology is made in three subsequent steps. During the first phase, the average MF coefficients of the tires of an axle and the relaxation lengths are identified through an extended Kalman filter. Then the vertical loads and the slip angles at each tire are estimated. The results of these two steps are used as inputs to the last phase, where, the MF-Tyre model coefficients for each individual tire are identified through a constrained minimization approach. Results of the identification procedure have been compared with experimental data collected on a sport vehicle equipped with different tires for the front and the rear axles and instrumented with dynamometric hubs for tire contact forces measurement. Thus, a direct matching between the measured and the estimated contact forces could be performed, showing a successful tire model identification. As a further verification of the obtained results, the identified tire model has also been compared with laboratory tests on the same tire. A good agreement has been observed for the rear tire where suspension compliance is negligible, while front tire data are comparable only after including a suspension compliance compensation term into the identification procedure.


2006 ◽  
Vol 52 (2) ◽  
pp. 325-328 ◽  
Author(s):  
Paul Froom ◽  
Zvi Shimoni

Abstract Background: The aim of this study was to explore whether electronically retrieved laboratory data can predict mortality in internal medicine departments in a regional hospital. Methods: All 10 308 patients hospitalized in internal medicine departments over a 1-year period were included in the cohort. Nearly all patients had a complete blood count and basic clinical chemistries on admission. We used logistic regression analysis to predict the 573 deaths (5.6%), including all variables that added significantly to the model. Results: Eight laboratory variables and age significantly and independently contributed to a logistic regression model (area under the ROC curve, 88.7%). The odds ratio for the final model per quartile of risk was 6.44 (95% confidence interval, 5.42–7.64), whereas for age alone, the odds ratio per quartile was 2.01 (95% confidence interval, 1.84–2.19). Conclusions: A logistic regression model including only age and electronically retrieved laboratory data highly predicted mortality in internal medicine departments in a regional hospital, suggesting that age and routine admission laboratory tests might be used to ensure a fair comparison when using mortality monitoring for hospital quality control.


2018 ◽  
Vol 25 (10) ◽  
pp. 1292-1300 ◽  
Author(s):  
Sharidan K Parr ◽  
Matthew S Shotwell ◽  
Alvin D Jeffery ◽  
Thomas A Lasko ◽  
Michael E Matheny

Abstract Objective Standards such as the Logical Observation Identifiers Names and Codes (LOINC®) are critical for interoperability and integrating data into common data models, but are inconsistently used. Without consistent mapping to standards, clinical data cannot be harmonized, shared, or interpreted in a meaningful context. We sought to develop an automated machine learning pipeline that leverages noisy labels to map laboratory data to LOINC codes. Materials and Methods Across 130 sites in the Department of Veterans Affairs Corporate Data Warehouse, we selected the 150 most commonly used laboratory tests with numeric results per site from 2000 through 2016. Using source data text and numeric fields, we developed a machine learning model and manually validated random samples from both labeled and unlabeled datasets. Results The raw laboratory data consisted of >6.5 billion test results, with 2215 distinct LOINC codes. The model predicted the correct LOINC code in 85% of the unlabeled data and 96% of the labeled data by test frequency. In the subset of labeled data where the original and model-predicted LOINC codes disagreed, the model-predicted LOINC code was correct in 83% of the data by test frequency. Conclusion Using a completely automated process, we are able to assign LOINC codes to unlabeled data with high accuracy. When the model-predicted LOINC code differed from the original LOINC code, the model prediction was correct in the vast majority of cases. This scalable, automated algorithm may improve data quality and interoperability, while substantially reducing the manual effort currently needed to accurately map laboratory data.


2021 ◽  
Vol 15 (5) ◽  
pp. 76-79
Author(s):  
E. S. Aronova ◽  
B. S. Belov

The article describes the clinical observation of the onset of polyarthritis after COVID-19. Clinical data, laboratory tests' and instrumental methods results in dynamics, as well as approaches to therapy are presented. The discussion reflects modern views on the causes of the development of articular syndrome after SARS-CoV-2, with special attention to the need for a careful study of the history, clinical and laboratory data of patients with COVID-19.


Author(s):  
Lars C. Gansel ◽  
Siri Rackebrandt ◽  
Frode Oppedal ◽  
Thomas A. McClimans

This study explores the average flow field inside and around stocked Atlantic salmon (Salmo salar L.) fish cages. Laboratory tests and field measurements were conducted to study flow patterns around and through fish cages and the effect of fish on the water flow. Currents were measured around an empty and a stocked fish cage in a fjord to verify the results obtained from laboratory tests without fish and to study the effects of fish swimming in the cage. Fluorescein, a nontoxic, fluorescent dye, was released inside a stocked fish cage for visualization of three-dimensional flow patterns inside the cage. Atlantic salmon tend to form a torus shaped school and swim in a circular path, following the net during the daytime. Current measurements around an empty and a stocked fish cage show a strong influence of fish swimming in this circular pattern: while most of the oncoming water mass passes through the empty cage, significantly more water is pushed around the stocked fish cage. Dye experiments show that surface water inside stocked fish cages converges toward the center, where it sinks and spreads out of the cage at the depth of maximum biomass. In order to achieve a circular motion, fish must accelerate toward the center of the cage. This inward-directed force must be balanced by an outward force that pushes the water out of the cage, resulting in a low pressure area in the center of the rotational motion of the fish. Thus, water is pulled from above and below the fish swimming depth. Laboratory tests with empty cages agree well with field measurements around empty fish cages, and give a good starting point for further laboratory tests including the effect of fish-induced currents inside the cage to document the details of the flow patterns inside and adjacent to stocked fish cages. The results of such experiments can be used as benchmarks for numerical models to simulate the water flow in and around net pens, and model the oxygen supply and the spreading of wastes in the near wake of stocked fish farms.


1998 ◽  
Vol 7 (6) ◽  
pp. 096369359800700 ◽  
Author(s):  
E. Gutiérrez ◽  
G. Di Salvo ◽  
J.M. Mieres ◽  
L. Mogensen ◽  
E. Shahidi ◽  
...  

In this paper we outline the development of an all-in-one composite reinforcing formwork system for manufacturing reinforced concrete elements, in particular, we describe the main experimental tests carried out on an 8 metre beam using high strength concrete poured and bonded on a hybrid, glass/carbon fibre formwork.


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