Water Sensitivity of Hemp-Foam Concrete

2022 ◽  
Author(s):  
Abdelrahman Mohamad ◽  
Fouzia Khadraoui ◽  
Nassim Sebaibi ◽  
Mohamed Boutouil ◽  
Daniel Chateigner
Keyword(s):  
Direct Method ◽  
Direct Methods ◽  
Capillary Absorption ◽  
Foam Concrete ◽  
Production Methods ◽  
Granulated Blast Furnace Slag ◽  
Water Sensitivity ◽  
Foamed Concrete ◽  
Experimental Protocols ◽  
Hemp Shiv

The necessity to build energy-efficient and low environmental impact buildings favors the development of biobased light-weight materials as hemp-foam concretes. In this context, experimental protocols were developed to study the effects of hemp shiv and the production methods on the water sensitivity of bio-based foamed concrete (BBFC). Foam concrete incorporates several materials and compounds: cement, protein-based foaming agent, ground granulated blast–furnace slag, metakaolin as a binder, and hemp shiv as bio-based aggregates. The study investigated first the effect of the incorporation of hemp shiv (from 0 to 15 vol%) and then the elaboration method, comparing direct method versus preformed method on the resulting physical properties, the isotherms sorption-desorption and the capillary water absorption of hemp-foam concretes. We observe an increasing porosity of the concrete with hemp shives content. Additionally, hemp shives increase the adsorption and the capillary absorption of water. Moreover, the preformed method produces concretes more sensitive to water than the direct methods since it increases its porosities.

scholarly journals Application and benchmarking of a direct method to optimize the fuel consumption of a diesel electric locomotive

2018 ◽  
Vol 232 (9) ◽  
pp. 2272-2289 ◽  
Author(s):  
V Macian ◽  
C Guardiola ◽  
B Pla ◽  
A Reig
Keyword(s):  
Optimal Control ◽  
Direct Method ◽  
Minimum Principle ◽  
Optimization Technique ◽  
Direct Methods ◽  
Optimization Methods ◽  
Computational Time ◽  
Electric Locomotive ◽  
Pontryagin Minimum Principle ◽  
A Direct Method

This paper addresses the optimal control of a long-haul passenger train to deliver minimum-fuel operations. Contrary to the common Pontryagin minimum principle approach in railroad-related literature, this work addresses this optimal control problem with a direct method of optimization, the use of which is still marginal in this field. The implementation of a particular direct method based on the Euler collocation scheme and its transcription into a nonlinear problem are described in detail. In this paper, this optimization technique is benchmarked with well-known optimization methods in the literature, namely dynamic programming and the Pontryagin minimum principle, by simulating a real route. The results showed that the direct methods are on the same level of optimality compared with other algorithms while requiring reduced computational time and memory and being able to handle very complex dynamic systems. The performance of the direct method is also compared to the real trajectory followed by the train operator and exhibits up to 20% of fuel saving in the example route.

Thermal Insulating and Constructive Foamed Concrete on a Composite Gypsum Binder

2019 ◽  
Vol 974 ◽  
pp. 125-130 ◽  
Author(s):  
Natalia V. Chernyisheva ◽  
Svetlana V. Shatalova ◽  
Maria Yu. Drebezgova ◽  
Evgeniy N. Lesnichenko
Keyword(s):  
Concrete Mixture ◽  
Foam Concrete ◽  
Thermal Insulating ◽  
Mineral Addition ◽  
Foamed Concrete ◽  
Stepwise Loading ◽  
Cellular Concrete ◽  
Loading Scheme

The article discusses the possibility of obtaining the effective thermal insulating and constructive foamed concrete on a composite gypsum binder. The composition was selected, the stepwise loading scheme of the foam concrete mixture components was proposed, the properties and microstructure of cellular concrete based on a composite gypsum binder with mineral addition of finely-dispersed concrete scrap were studied.

Performance of Stabilized Earth with Wheat Straw and Slag

MRS Advances ◽  
2020 ◽  
Vol 5 (25) ◽  
pp. 1285-1294 ◽  
Author(s):  
W Benhaoua ◽  
K. Grine ◽  
S. Kenai
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Low Cost ◽  
Construction Material ◽  
Soil Samples ◽  
Capillary Absorption ◽  
Wetting And Drying ◽  
Environment Friendly ◽  
Granulated Blast Furnace Slag ◽  
Local Soil

ABSTRACTStabilized earth is a very ancient material that has been used in many countries as a low cost, environment friendly construction material. However, its durability under humid environments is low. Stabilization using cement, lime and natural fibres could enhance its durability and lowers the risk of cracking. This paper presents an experimental investigation into the performance of stabilised local soil by either, cement mixed with a proportion of granulated blast furnace slag (GBFS) /or straw naturel fibres. Unconfined compressive strength (UCS), shrinkage, wetting and drying, capillary absorption and thermal conductivity tests were performed on both untreated soil samples and stabilised soil samples. The results show that stabilising the soil with cement and GBFS increased both compressive strength, durability, thermal conductivity and decreased the capillary absorption and the shrinkage. The addition of natural wheat fibres increased the capillary absorption but leads to a decrease in the thermal conductivity and to a further reduction in the shrinkage and hence a better insulating less prone to cracking material.

scholarly journals The compressibility of aqueous solutions II

1934 ◽  
Vol 146 (858) ◽  
pp. 640-650 ◽  
Keyword(s):  
Pressure Range ◽  
Direct Method ◽  
Direct Methods ◽  
Cane Sugar ◽  
Excess Pressure ◽  
Subsequent Work ◽  
Molecular Weights ◽  
In Series ◽  
Related Compounds ◽  
A Direct Method

In an earlier communication, Perman and Urry described the measurement, by a direct method, of the compressibility coefficients of aqueous solution of urea, cane sugar, potassium chloride, and calcium chloride, over a range temperatures and concentrations. Their work was over the pressure range 0-200 atmospheres excess pressure. They were able to apply their together with other data obtained by their co-workers, to an extension Porter's theory of compressible solutions, and thus obtained values for osmotic pressures of those solutions which agreed very well with the obtained by more direct methods. The present work is a continuation of this and subsequent work (unpublished) by these authors. It was intended, especially, to investigate the effect of nature of the solute molecule upon the compressibility, and, for this reason the choice of solutes was particularly important. A number of series chemically related compounds were used where only one part of the mole varied in a progressive manner from substance to substance. In series there was no chemical relationship, but the members had the empirical formula and their molecular weights were therefore simple multi of each other.

Abinitiostructure solution of nucleic acids and proteins by direct methods: reciprocal-space and real-space approach

2005 ◽  
Vol 38 (1) ◽  
pp. 217-222 ◽  
Author(s):  
Krishna Chowdhury ◽  
Soma Bhattacharya ◽  
Monika Mukherjee
Keyword(s):  
Nucleic Acids ◽  
Direct Method ◽  
Heavy Atom ◽  
Direct Methods ◽  
Disulfide Bridge ◽  
Real Space ◽  
Reciprocal Space ◽  
Space Groups ◽  
Data Resolution ◽  
Modification Procedure

Anab initiomethod for solving macromolecular structures is described. The heavy atom(s) or some disulfide bridge in the structure are located from the phase sets selected on the basis of a figure of merit of a reciprocal-space-based multiple-solution direct method. Subsequent weighted Fourier recycling reveals recognizable structures for two nucleic acids where data resolution is 1.3 Å or better. With lower than 1.3 Å data resolution or sulfur as the heaviest atom in the structure, the phase refinement has been carried out using the density modification procedure (PERP) operating in direct space. The resulting electron density map can readily be interpreted. The methodology has been illustrated with six known nucleic acids and proteins crystallizing in different space groups. It has proved to be fast, simple to use and a very effective tool for solving macromolecular structures with data resolution up to 1.7 Å.

scholarly journals Cost-effectiveness in the diagnosis of tuberculosis: choices in developing countries

2014 ◽  
Vol 8 (01) ◽  
pp. 024-038 ◽  
Author(s):  
Paola Molicotti ◽  
Alessandra Bua ◽  
Stefania Zanetti
Keyword(s):  
Direct Method ◽  
Infectious Agent ◽  
Direct Methods ◽  
Sputum Smear ◽  
Smear Microscopy ◽  
Culture Methods ◽  
Molecular Tests ◽  
Treat All ◽  
Indirect Tests ◽  
Hiv Aids

Tuberculosis remains one of the major causes of global death from a single infectious agent. This situation is worsened by the HIV/AIDS pandemic because one-third of HIV/AIDS patients are co-infected with Mycobacterium tuberculosis. Failure to control the spread of tuberculosis is largely due to our inability to detect and treat all infectious cases of pulmonary tuberculosis in a timely manner, allowing continued M. tuberculosis transmission within communities. Diagnosis of tuberculosis can be made using indirect and direct methods. The indirect tests, such as interferon-gamma release assays, provide a new diagnostic method for M. tuberculosis infection, but do not discriminate between infection and active disease. The most common direct method for diagnosing TB worldwide is sputum smear microscopy (developed more than 100 years ago), where bacteria are observed in sputum samples examined under a microscope. In countries with more developed laboratory capacities, cases of tuberculosis may also be diagnosed using culture methods (the current gold standard) or, increasingly, using rapid molecular tests. In this review, we discuss the traditional methods for the diagnosis of tuberculosis. We also discuss other inexpensive assays that can be used to detect the presence of M. tuberculosis.

scholarly journals Difference in Bias Approach for Commutability Assessment: Application to Frozen Pools of Human Serum Measured by 8 Direct Methods for HDL and LDL Cholesterol

2015 ◽  
Vol 61 (8) ◽  
pp. 1107-1113 ◽  
Author(s):  
William J Korzun ◽  
Göran Nilsson ◽  
Lorin M Bachmann ◽  
Gary L Myers ◽  
Ikunosuke Sakurabayashi ◽  
...  
Keyword(s):  
Random Error ◽  
Ldl Cholesterol ◽  
Direct Method ◽  
Direct Methods ◽  
Measurement Procedure ◽  
Critical Value ◽  
Reference Measurement ◽  
Reference Procedure ◽  
Error Components ◽  
The Difference

Abstract BACKGROUND We used a difference in bias approach to evaluate the commutability of 4 frozen serum pools for 8 direct methods for measurement of HDL and LDL cholesterol (HDLC and LDLC). METHODS Freshly collected nonfrozen sera from 138 diseased and 37 nondiseased patients and 4 frozen pools from the CDC Lipid Standardization Program were measured by direct methods and by the beta-quantification reference measurement procedure of the CDC. We used an error components model to estimate the difference in the bias component of error plus its uncertainty for frozen pools vs patient samples between the direct method and the reference procedure. Frozen pools with bias differences less than a critical value determined by either medical requirements for bias or the random error components of the measurement procedures were considered commutable. RESULTS On the basis of medical requirement criteria, 1 of the 4 frozen pools was commutable for most of the HDLC methods for both diseased and nondiseased patients, and none was commutable for LDLC methods. On the basis of random error criteria, all of the frozen pools were generally commutable for all of the HDLC methods for both diseased and nondiseased patients, and 1 of the 4 frozen pools was generally commutable for most of the LDLC methods for both diseased and nondiseased patients. CONCLUSIONS Commutability was assessed as the closeness of agreement of the difference in bias between a reference material and a set of patient samples. Criteria for commutability could be based on fixed medical requirements for bias or on random error components.

Direct and Indirect Methods for Calculating Thermal Emission From Layered Structures With Nonuniform Temperatures

2011 ◽  
Vol 133 (7) ◽  
Author(s):  
L. P. Wang ◽  
S. Basu ◽  
Z. M. Zhang
Keyword(s):  
Temperature Distribution ◽  
Thermal Emission ◽  
Local Density ◽  
Direct Method ◽  
Direct Methods ◽  
Layered Structures ◽  
Nonuniform Temperature ◽  
Indirect Methods ◽  
Nonuniform Temperature Distribution ◽  
Direct And Indirect Methods

The determination of emissivity of layered structures is critical in many applications, such as radiation thermometry, microelectronics, radiative cooling, and energy harvesting. Two different approaches, i.e., the “indirect” and “direct” methods, are commonly used for computing the emissivity of an object. For an opaque surface at a uniform temperature, the indirect method involves calculating the spectral directional-hemispherical reflectance to deduce the spectral directional emissivity based on Kirchhoff’s law. On the other hand, a few studies have used a combination of Maxwell’s equations with the fluctuation-dissipation theorem to directly calculate the emissivity. The present study aims at unifying the direct and indirect methods for calculating the far-field thermal emission from layered structures with a nonuniform temperature distribution. Formulations for both methods are given to illustrate the equivalence between the indirect and the direct methods. Thermal emission from an asymmetric Fabry–Pérot resonance cavity with a nonuniform temperature distribution is taken as an example to show how to predict the intensity, emissivity, and the brightness temperature. The local density of states, however, can only be calculated using the direct method.

A procedure for ab initio phasing of one-wavelength anomalous scattering data from proteins – combining direct methods with the solvent flattening technique

1997 ◽  
Vol 212 (2) ◽  
Author(s):  
X. F. Zheng ◽  
Y. X. Gu ◽  
C. D. Zheng ◽  
Y. D. Mo ◽  
H. F. Fan ◽  
...  
Keyword(s):  
Ab Initio ◽  
Diffraction Data ◽  
Direct Method ◽  
Direct Methods ◽  
Special Care ◽  
Scattering Data ◽  
Anomalous Scattering ◽  
Phase Ambiguity ◽  
Moderate Size ◽  
Subsequent Phase

AbstractBoth direct methods and the solvent flattening technique have been proved capable of breaking the phase ambiguity intrinsic in one-wavelength anomalous scattering (OAS) data. However, in theory, while direct methods are better in deriving starting phases from OAS data, the solvent flattening technique is more powerful in the subsequent phase refinement. A procedure is described in this paper which combines direct methods with the solvent flattening technique for phasing of OAS data. The procedure has been tested with the known protein RNase Sa. This protein is of moderate size, and the diffraction data were collected routinely without taking special care for the recording of Friedels. The test proved that the combination of the direct method and the solvent flattening leads to a much better result than that from either method alone.

The Measurement of Very Low Frictional Torques in Rotating Equipment

1960 ◽  
Vol 82 (4) ◽  
pp. 382-386
Author(s):  
M. Zaid ◽  
I. S. Tolins
Keyword(s):  
Direct Method ◽  
Direct Methods ◽  
Evaluation Technique ◽  
Air Bearings ◽  
Design Improvement ◽  
Good Evaluation ◽  
Zero Values ◽  
Rotating Equipment ◽  
Correct Application

In the design of high precision, rotating equipment such as air bearings, gyroscopes, etc., it has become possible to reduce the frictional torques to “almost zero” values. The measurement and classification of the sources of these minute torques during rotation is exceedingly difficult, but very important for correct application and further design improvement. It is the purpose of this paper to present two techniques for the measurement and discrimination of the torques, and an example showing the accuracy of these techniques. Although these methods were designed specifically for the measurements of low torques, they work equally well for any magnitude and as such present a good evaluation technique. A comparison made with the values obtained by one of the better “direct” methods indicates that the direct method is inadequate.

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