Effect of retempering on the engineering properties of superplasticized concrete

The effect of retempering non-superplasticized and superplasticized concrete (having nominal strengths of 17, 24, 31, 38 N mm⁻²) on the compressive strength, modulus of rupture, splitting tensile strength, modulus of elasticity and Poisson’s ratio was studied. Retempering of non-superplasticized concrete mixes reduces their engineering properties, whereas retempering of superplasticized mixes resulted in marginal increase in engineering properties.     

Experimental and theoretical investigation of non-isothermal transfer in hygroscopic building materials

In this paper a modified two-dimensional Luikov model for evaluating the non-isothermal moisture migration in porous building materials was proposed. The coupled heat and moisture transfer problem was modeled. Vapor content and temperature were chosen as the principal driving potentials. The coupled equations were solved by a numerical method, which consists of a finite difference technique with a fully implicit scheme in time. Two validation experiments were developed in this study. The evolution of transient moisture distributions in both one-dimensional and two-dimensional cases was measured. A comparison between experimental results and those obtained by the numerical model proves that they are fully consistent with each other. The modified model can be integrated into a whole building heat, air and moisture transfer model.     

Trypsin inhibitor activity in vicia faba beans

Extracts of mature green, dry and germinated Vicia faba beans depressed the trypsin activity of casein. Germination of Vicia faba beans (for 60 h) lowered the trypsin inhibitor (TI) activity. 0.171M Saline was the most efficient extractant for the TI. Minimal amounts of the TI were extracted in the pH range 4 to 5. The TI of Vicia faba beans was undialysable. The inhibitor activity originated in the seeds at the beginning of pod formation and increased with development of maturity. TI was active only towards trypsin and inactive towards papain, rennin and pepsin. Chromatographing Vicia faba bean proteins, possessing antitryptic activity, on a column of DEAE-cellulose yielded six peaks, all of which possessed antitryptic activity.     

Experimental and analytical study of residual stresses relaxation in nitrided 42CrMo4 parts

Initial compressive residual stresses, induced by ionic nitriding treatments, relax during component operating life and it is important to consider the relaxation phenomenon in the design of the component. The paper presents three analytical models (Seungho Han et al., Zaroog and Kodama) to estimate the level of residual stress after cyclic loading. The initial and final residual stresses has been measured after each loading cycle for many load magnitudes using x‐ray diffraction. It was found that about 40 %–50 % of the maximum residual stresses are relaxed during the first cycle. The reduction in the residual stress, are dependent on the applied load because of the plastic deformation caused by the superposition between the nitrided residual stress and the applied load. It was found that the estimated average values by analytical models are comparable with the results of experimental studies after cyclic loading.     

2D inverse problem in a distributed parameter system

In this paper, we present a numerical solution for an inverse heat problem to estimate 2D space-wise coefficient in a parabolic system describing heat transfer. The inverse problem is recast into an optimization problem solved with a conjugate gradient method. This approach use the non linear optimization formulation by minimizing a cost function taking into account both the measured outputs of the system and the outputs calculated by means of the model. The solution is performed by using the free finite element software FreeFem. Numerical example is carried out to check the validity of the proposed method.     

System identification and uncertainty modeling of an electromechanical actuator

The electromechanical actuator (EMA) is of interest for applications which require easy control and high dynamics. This article deals with the analytical and uncertainties modeling, experimental identification, and model validation of a position control EMA and its “motor with harmonic drive” subsystem. They are identified and modeled as linear systems with parametric uncertainty using their experimental input–output data. The captured data, related to several working points under different conditions, were used for model estimation and validation purposes. Furthermore, the discrepancies between the linear model and the actual system, due to nonlinearities, were estimated as multiplicative uncertainty. The model is validated on the base of reproducing system behavior within acceptable bounds with minimum error. Validation results proved the derived model viability to be used for designing a robust EMA system to perform within acceptable bandwidth.     

Three novel angiotensin I-converting enzyme (ACE) inhibitory peptides from cuttlefish (Sepia officinalis) using digestive proteases

The angiotensin I-converting enzyme (ACE) inhibitory activities of protein hydrolysates prepared from muscle of cuttlefish (Sepia officinalis) by treatment with various digestive proteases were investigated. The most active hydrolysate was obtained with the crude protease extract from the hepatopancreas of cuttlefish (64.47 ± 1.0% at 2 mg of dry weight/ml) with a degree of hydrolysis of 8%. By gel filtration on Sephadex G-25 and RP-HPLC on C18 column, three novel peptides with high ACE-inhibitory activity were purified and their molecular masses and amino acid sequences were determined. The three peptides Val-Tyr-Ala-Pro, Val-Ile-Ile-Phe and Met-Ala-Trp with IC₅₀ values of 6.1, 8.7 and 16.32 μM, respectively, were novel ACE-inhibitory peptides. Lineweaver–Burk plots suggest that the three purified peptides act as non-competitive inhibitors against ACE. These results suggest that some peptides from cuttlefish could be a beneficial ingredient for nutraceuticals against hypertension.     

合理的失效统计是改善可利用率的关键

正如在大部分其他领域，维修优化在风能领域也很重要。一种合理的失效统计能使维修费用大大降低，同时改善风力发电机可利用率。对必要数据、数据结构、可靠性特性指示等进行讨论，并回顾改善可利用率的方法。此外，将概述近海风电场如何收集和评估未来设备运行。     

Asymmetric X-Ray Diffraction

Abstract

Physical phenomena characteristic of asymmetric X-ray diffraction schemes for perfect crystals, including diffraction under conditions of specular reflection, have been considered in detail. The principles underlying asymmetric crystal monochromators, achievements in obtaining narrow collimated X-ray beams, and the latest results on the application of asymmetric schemes in the investigation of thin subsurface layers are stated; along with the fundamentals of asymptotic Bragg diffraction, specific features of the grazing Bragg-Laue scheme and the analysis of amorphous sublayers with the use of the surface Bragg peak. Emphasis is placed on the application of asymmetric diffraction schemes in the method of X-ray standing waves to increase sensitivity (in recording of photoelectrons, fluorescence, and Compton scattering) and to study the characteristic features of the diffraction process in strongly asymmetric geometry.