Syntax-directed compression of program files

Parsing can be applied to compress source programs. A suitably encoded parse tree, together with the symbol table, constitutes a very compact representation of the program. The paper reports a Prolog implementation of the method, including automatic, syntax-directed, encoder and decoder generators. The test results show compression gains of 50–60 per cent.     

Morphological,mechanical, tribological,and thermal expansion properties of organoclay reinforced polyethylene composites

The morphological, mechanical, thermal, and tribological properties of high‐density polyethylene (HDPE) composites reinforced with organo‐modified nanoclay (3 and 6 wt%) were studied. A commercial maleic anhydride‐based polymeric compatibilizer (PEgMA) was used to improve the adhesion between the polyethylene and clay. Transmission electron microscopy (TEM) characterization of composites revealed that nanoclay exists mainly in a multilayered structure in the HDPE matrix. Mechanical testing of composites showed that Young's modulus and tensile strength increased with nanoclay content. Coefficients of the linear thermal expansion (CLTE) of HDPE–PEgMA–clay composites were slightly lower in the flow direction than those of HDPE–PEgMA. The tribological properties were measured in dry conditions against a steel counterface. The friction coefficient of the matrix was decreased by the addition of clay. Electron microscopic results suggested that the wear mechanism for HDPE and HDPE composites was mainly adhesive. Clay agglomerates were observed on the worn surfaces of the composites, which may partly explain decreased friction. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Quantification of metabolites from single-voxelin vivo 1H NMR data of normal human brain by means of time-domain data analysis

We present here a combination of time-domain signal analysis procedures for quantification of human brainin vivo ¹H NMR spectroscopy (MRS) data. The method is based on a separate removal of a residual water resonance followed by a frequency-selective time-domain line-shape fitting analysis of metabolite signals. Calculation of absolute metabolite concentrations was based on the internal water concentration as a reference. The estimated average metabolite concentrations acquired from six regions of normal human brain with a single-voxel spin-echo technique for theN-acetylaspartate, creatine, and choline-containing compounds were 11.4±1.0,6.5±0.5, and 1.7±0.2 mmol kg^–1 wet weight, respectively. The time-domain analyses ofin vivo ¹H MRS data from different brain regions with their specific characteristics demonstrate a case in which the use of frequency-domain methods pose serious difficulties.     

Aerosol analysis of residual and nanoparticle fractions from spray pyrolysis of poorly volatile precursors

The quality of aerosol‐produced nanopowders can be impaired by micron‐sized particles formed due to non‐uniform process conditions. Methods to evaluate the quality reliably and fast, preferably on‐line, are important at industrial scales. Here, aerosol analysis methods are used to determine the fractions of nanoparticles and micron‐sized residuals from poorly volatile precursors. This is accomplished using aerosol instruments to measure the number and mass size distributions of Liquid Flame Spray‐generated alumina and silver particles produced from metal nitrates dissolved in ethanol and 2‐ethylhexanoic acid (EHA). The addition of EHA had no effect on silver, whereas, 5% EHA concentration was enough to shift the alumina mass from the residuals to nanoparticles. The size‐resolved aerosol analysis proved to be an effective method for determining the product quality. Moreover, the used on‐line techniques alone can be used to evaluate the process output when producing nanopowders, reducing the need for tedious off‐line analyses. © 2016 American Institute of Chemical Engineers AIChE J, 63: 881–892, 2017     

Energy dissipation in natural rubber latex films: The effect of stabilizers,leaching and acetone-treatment

Natural rubber (NR) is a versatile material possessing outstanding mechanical properties, which can be used in multiple applications including the rapidly developing dielectric elastomer generators (DEGs). One of the drawbacks of the existing DEGs is their low efficiency, which can be improved by lowering the dielectric and mechanical losses originating from the material. Therefore, the present research was focusing on assessing the ways to minimize the dielectric and mechanical losses of NR films rather than developing a DEG. In this article, the effect of natural proteins and the rubber stabilizers on energy dissipation of NR films was evaluated. Moreover, the effect of sample posttreatment (with water and acetone), curing and time after cure was discussed. As a result, deproteinized NR stabilized by ammonium caseinate outperformed unmodified NR due to reduced dielectric losses, mechanical hysteresis and stress relaxation. Moreover, the posttreatment methods were found to moderately reduce the material-relates losses.     

Incorporation of n-3 fatty acids into plasma lipid fractions, and erythrocyte membranes and platelets during dietary supplementation with fish, fish oil, and docosahexaenoic acid-rich oil among healthy young men

The effects of n-3 fatty acid supplementation in the form of fresh fish, fish oil, and docosahexaenoic acid (DHA) oil on the fatty acid composition of plasma lipid fractions, and platelets and erythrocyte membranes of young healthy male students were examined. Altogether 59 subjects (aged 19–32 yr, body mass index 16.8–31.3 kg/m²) were randomized into the following diet groups: (i) control group; (ii) fish diet group eating fish meals five times per week [0.38±0.04 g eicosapentaenoic acid (EPA) and 0.67±0.09 g DHA per day]; (iii) DHA oil group taking algae-derived DHA oil capsules (1.68 g/d DHA oil group taking algae-derived DHA oil capsules (1.68 g/d DHA in triglyceride form); and (iv) fish oil group (1.33 g EPA and 0.95 g DHA/d as free fatty acids) for 14 wk. The fatty acid composition of plasma lipids, platelets, and erythrocyte membranes was analyzed by gas chromatography. The subjects kept 4-d food records four times during the study to estimate the intake of nutrients. In the fish diet, in DHA oil, and in fish oil groups, the amounts of n-3 fatty acids increased and those of n-6 fatty acids decreased significantly in plasma lipid fractions and in platelets and erythrocyte membranes. A positive relationship was shown between the total n-3 polyunsaturated fatty acids (PUFA) and EPA and DHA intake and the increase in total n-3 PUFA and EPA and DHA in all lipid fractions analyzed. DHA was preferentially incorporated into phospholipid (PL) and triglyceride (TG) and there was very little uptake in cholesterol ester (CE), while EPA was preferentially incorporated into PL and CE. The proportion of EPA in plasma lipids and platelets and erythrocyte membranes increased also by DHA supplementation, and the proportion of linoleic acid increased in platelets and erythrocyte membranes in the DHA oil group as well. These results suggest retroconversion of DHA to EPA and that DHA also interferes with linoleic acid metabolism.     

Towards traceable particle number concentration standard: Single charged aerosol reference (SCAR)

A concept of realizing a standard for aerosol particle number concentration was tested, based on generating singly charged aerosol particles in the size range from 10 up to 500 nm. To this end, a device named single-charged aerosol reference (SCAR) was designed, built, and tested. The device is based on electrical charging of nanoparticles and subsequent growth of the particles. With an accurate measurement of volume flow and electrical current from the singly charged particles, the number concentration can be accurately, and in the end, traceably determined. Laboratory tests have shown that the device can be used to generate a narrow (GSD<1.3) particle size distribution of singly charged particles. The device can be used for traceable calibration of instruments measuring the number concentration of the particles.     

A Synchronized Wireless Sensor Network for Experimental Modal Analysis in Structural Health Monitoring

Abstract: Structural health monitoring aims to provide an accurate diagnosis of the condition of civil infrastructures during their life span using data acquired by sensors. Wireless sensor networks represent a suitable monitoring technology to collect reliable information about the structure's condition, replacing visual inspections, and reducing installation and maintenance time and costs. This article introduces a time synchronized and configurable wireless sensor network for structural health monitoring enabling a highly accurate identification of the modal properties of the monitored structure. The wireless sensor nodes forming the network are equipped with a 3‐axis digital accelerometer and a temperature and humidity sensor. The implemented Medium Access Control layer time synchronization protocol (μ‐Sync) ensures a highly accurate synchronicity among the samples collected by the nodes, the absolute error being constantly below 10 μs, also when high sampling frequency (up to 1 kHz) and extended sampling periods (up to 10 minutes) are applied. The experimental results obtained on a wooden model bridge, compared with those derived from acceleration signals acquired by high‐quality wired sensors, show that the so synchronized wireless sensor nodes allow a precise identification of the natural frequencies of vibration of the monitored structure (1% maximum relative difference).     

The long-term effects of logging residue removal on forest floor nutrient capital, foliar chemistry and growth of a Norway spruce stand

This study compared the nutrient capital of the forest floor, the nutrient status of trees, and the growth of a stand of Norway spruce (Picea abies L. (Karst.)) planted on a whole-tree harvesting treatment (needles left on site) with a conventional stem-only harvesting treatment 30 years after clearcutting. No significant treatment effects were detected in the amount of organic matter, the amounts of nutrients in the forest floor, or the concentrations of foliar nutrients. The results indicate that whole-tree harvesting with the needles left on the site did not reduce the long-term nutrient capital of the forest floor or the nutritional status of trees. Whole-tree harvesting significantly reduced the height of dominant spruce compared to stem-only harvesting, however the stem volume of dominant spruce did not differ between the harvesting treatments. The greater height growth of the dominant trees in the stem-only harvesting treatment could be attributed to indirect factors other than changes in site resource availability (e.g. protection against frost damage), and hence the effect of whole-tree harvesting on potential site productivity was inconclusive due to the confounding effect of site factors. In the whole-tree harvesting treatment, the total stem volume of the stand and, consequently, the actual site productivity, was lower when compared to stem-only harvesting due to the lower density of naturally regenerated seedlings.     

Maintenance optimization for a multi-unit system with digital twin simulation

Journal of Intelligent Manufacturing - Optimization of operations and maintenance (O&amp;M) in the industry is a topic that has been largely studied in the literature. Many authors focused on...