Analysis of Flame-Retardant Performance Based on Wood Density and Flame-Retardant Treatment Method

For this study, four types of wood with different densities (spruce and low-, medium-, and high-density fiberboards) were selected from wood widely used as materials in real life, particularly in architectural interiors. For each wood type, flame-retardant paints (water- and oil-based) and flame-retardant liquids were applied two to five times using three flame-retardant treatment methods (roller, brush, and spray) to test the flame-retardant performance. For the four types of wood specimens with different densities, their flame-retardant performances and ignition times were compared and analyzed according to the applied flame-retardant paint (water- and oil-based) and liquid, treatment method, and frequency at which a specific paint was applied. These results can be used as empirical data on changes in flame-retardant performance based on density of wood and flame-retardant treatment method.

SENSOR SYSTEM DESIGN FOR PROPELLER TEST BENCH

The sensor system is a system that functions to detect signals that come from changes in energy such as electrical energy, physical energy, chemical energy, biological energy, mechanical energy, and so on. The propeller test bench is an propeller performance testing platform prior to propeller installation on an aircraft to ensure engine suitability. The purpose of this design is to test the performance capability of the engine with the right sensor system measurement tool so that it can generate the value of thrust, rpm speed, and the temperature of an engine which will be designed to be used in the learning process to support propulsion practicum activities. The method used in this research is an experimental method of sensor system design. The design of the sensor system consists of a tachometer as a rpm measurement sensor, a thermostat as a sensor to measure the temperature of the propeller spool and temperature of the engine fin, and also a load cell as a sensor to measure the thrust value.The sensor system test results were then validated using the measurement results by the sensor manufacturer. The test was carried out on a wood-type propeller measuring 22 x 8 chords 4,5 cm and 5 cm. Based on the test results, it is known that the chord wood type propeller is 4,5 cm, at the maximum rpm is 7021.7, the resulting thrust value is 6.75. In testing the 5cm chord wood type propeller shows the maximum speed of 6977.5 produces a thrust of 6.95. Validation was carried out on the measurement results of rpm and thrust, the average error factor obtained for 4,5 cm chord wood type propeller was 0.783%, while for 5 cm chord wood type propeller the average error factor obtained was 1.0582%. From the resulting average error, it can be concluded that the measuring instrument for this sensor system has good accuracy

A MATSUMOTO–MOSTOW RESULT FOR ZIMMER’S COCYCLES OF HYPERBOLIC LATTICES

Following the philosophy behind the theory of maximal representations, we introduce the volume of a Zimmer’s cocycle Γ × X → PO° (n, 1), where Γ is a torsion-free (non-)uniform lattice in PO° (n, 1), with n > 3, and X is a suitable standard Borel probability Γ-space. Our numerical invariant extends the volume of representations for (non-)uniform lattices to measurable cocycles and in the uniform setting it agrees with the generalized version of the Euler number of self-couplings. We prove that our volume of cocycles satisfies a Milnor–Wood type inequality in terms of the volume of the manifold Γ\ℍn. Additionally this invariant can be interpreted as a suitable multiplicative constant between bounded cohomology classes. This allows us to define a family of measurable cocycles with vanishing volume. The same interpretation enables us to characterize maximal cocycles for being cohomologous to the cocycle induced by the standard lattice embedding via a measurable map X → PO° (n, 1) with essentially constant sign.As a by-product of our rigidity result for the volume of cocycles, we give a different proof of the mapping degree theorem. This allows us to provide a complete characterization of maps homotopic to local isometries between closed hyperbolic manifolds in terms of maximal cocycles.In dimension n = 2, we introduce the notion of Euler number of measurable cocycles associated to a closed surface group and we show that it extends the classic Euler number of representations. Our Euler number agrees with the generalized version of the Euler number of self-couplings up to a multiplicative constant. Imitating the techniques developed in the case of the volume, we show a Milnor–Wood type inequality whose upper bound is given by the modulus of the Euler characteristic of the associated closed surface. This gives an alternative proof of the same result for the generalized version of the Euler number of self-couplings. Finally, using the interpretation of the Euler number as a multiplicative constant between bounded cohomology classes, we characterize maximal cocycles as those which are cohomologous to the one induced by a hyperbolization.

Exposure Determinants of Wood Dust, Microbial Components, Resin Acids and Terpenes in the Saw- and Planer Mill Industry

Objectives Sawmill workers have an increased risk of adverse respiratory outcomes, but knowledge about exposure–response relationships is incomplete. The objective of this study was to assess exposure determinants of dust, microbial components, resin acids, and terpenes in sawmills processing pine and spruce, to guide the development of department and task-based exposure prediction models. Methods 2474 full-shift repeated personal airborne measurements of dust, resin acids, fungal spores and fragments, endotoxins, mono-, and sesquiterpenes were conducted in 10 departments of 11 saw- and planer mills in Norway in 2013–2016. Department and task-based exposure determinants were identified and geometric mean ratios (GMRs) estimated using mixed model regression. The effects of season and wood type were also studied. Results The exposure ratio of individual components was similar in many of the departments. Nonetheless, the highest microbial and monoterpene exposure (expressed per hour) were estimated in the green part of the sawmills: endotoxins [GMR (95% confidence interval) 1.2 (1.0–1.3)], fungal spores [1.1 (1.0–1.2)], and monoterpenes [1.3 (1.1–1.4)]. The highest resin acid GMR was estimated in the dry part of the sawmills [1.4 (1.2–1.5)]. Season and wood type had a large effect on the estimated exposure. In particular, summer and spruce were strong determinants of increased exposure to endotoxin (GMRs [4.6 (3.5–6.2)] and [2.0 (1.4–3.0)], respectively) and fungal spores (GMRs [2.2 (1.7–2.8)] and [1.5 (1.0–2.1)], respectively). Pine was a strong determinant for increased exposure to both resin acid and monoterpenes. Work as a boilerman was associated with moderate to relatively high exposure to all components [1.0–1.4 (0.8–2.0)], although the estimates were based on 13–15 samples only. Cleaning in the saw, planer, and sorting of dry timber departments was associated with high exposure estimates for several components, whereas work with transportation and stock/finished goods were associated with low exposure estimates for all components. The department-based models explained 21–61% of the total exposure variances, 0–90% of the between worker (BW) variance, and 1–36% of the within worker (WW) variances. The task-based models explained 22–62% of the total variance, 0–91% of the BW variance, and 0–33% of the WW variance. Conclusions Exposure determinants in sawmills including department, task, season, and wood type differed for individual components, and explained a relatively large proportion of the total variances. Application of department/task-based exposure prediction models for specific exposures will therefore likely improve the assessment of exposure–response associations.