On the uncertainty of building acoustic measurements – Case study of a cross-laminated timber construction

If variations and uncertainty in building acoustic measurements can be controlled, construction costs can potentially be reduced since the building will not have to be acoustically over-designed. Field measurements of impact and airborne sound insulation were carried out for an industrially prefabricated cross-laminated timber (CLT) system of plate elements. The results from 18 rooms, forming three groups with respect to size, were compared to a similar study dealing with a prefabricated Volume Based Building (VBB) system. Large variations were found at frequencies below 100 Hz which is crucial for the low frequency adaptation terms connected to the weighted sound insulation indices. The measurement uncertainty was investigated by analysing the repeatability, measurement direction and the time dependence of the sound source. The variations due to the measurement procedure were found to be small compared to the total variations. It was also indicated that the variations in sound insulation are smaller with a prefabricated system compared to on-site production, since less work is required at the building site.     

Influence of cosmic radiation spectrum and its variation on the relative efficiency of LiF thermoluminescent detectors – Calculations and measurements

Lithium fluoride thermoluminescent detectors (TLD) were used for cosmic radiation dosimetry already in early 1960s. Since that time they have been constantly applied in numerous space missions for personal dosimetry, area monitoring, phantom measurements and dosimetry for biological experiments. The relative efficiency of TLDs, defined as the ratio of their response to a given radiation and to a reference radiation, is not constant, but depends on ionization density. This raises a question about the relative efficiency of TLDs exposed to the complex cosmic radiation spectrum encountered in Earth's orbit, which consists of a variety of particles, including heavy ions, the spectrum of which covers an extremely broad energy range. The present work is an attempt to find an answer to this question.The particle energy spectra were calculated for realistic flight conditions of the International Space Station (ISS). The calculation of the Galactic Cosmic Ray (GCR) component was based on the input spectra generated with the DLR model for solar minimum (2009) and solar maximum (2000) conditions. Contributions of trapped protons were estimated based on the AP8 model for solar minimum and maximum taking into account the altitude variations of the ISS. The interactions of the primary particles with the ISS were simulated with GEANT4 using a shielding geometry derived from the mass distribution of the Columbus Laboratory of the ISS and several constant aluminum shieldings. The calculated spectra were convoluted with the experimental data on the relative TL efficiency measured for ions ranging from H to Xe at various particle accelerators for two commonly applied TL-materials, namely LiF:Mg,Ti and LiF:Mg,Cu,P.The results showed the differences in the average TL-efficiency for these two TL-materials. For LiF:Mg,Ti the relative efficiency is within a few percent from unity for any of the analyzed values of shielding, altitude and solar cycle conditions. This means that one can assume cosmic radiation doses measured in Low Earth Orbit (LEO) with LiF:Mg,Ti detectors to be correct within such uncertainty. LiF:Mg,Cu,P underestimates the cosmic radiation doses by more than 15% in all cases. Altitude and solar cycle were found to have a very weak influence on the TL efficiency. In contrast, the influence of shielding thickness is quite significant. The reason for this is a change of contributions of radiation field components: trapped protons dominate at low shielding (97% of dose at 1 g/cm²), but are negligible above 60 g/cm², as well as changes within GCR spectrum (increase of dose due to lower LET secondaries for higher shielding). Shielding thickness affects both TLD types in different ways: the efficiency of LiF:Mg,Cu,P increases with increasing shielding thickness, while the efficiency of LiF:Mg,Ti shows some fluctuations, with a weak minimum for 60 g/cm². The response ratio of these TLDs decreases monotonically with the shielding thickness and could be used as an indicator for the average shielding conditions in which the TLDs were exposed.     

Long term changes in the distribution and δ15N values of individual soil amino acids in the absence of plant and fertiliser inputs

The long-term ‘biodegradation’ on soil amino acids was examined in the control plots of ‘42 parcelles’ experiment, established in 1928 at INRA, Versailles (France). None of the plots is cultivated, but is kept free of weeds, and mixed to a depth of 25 cm twice yearly. Topsoil (0–10 cm depth) samples collected in 1929, 1963 and 1997 were subjected to acid hydrolysis (6 N HCl) for comparison. The distribution and δ¹⁵N natural abundance of 20 individual amino acids in the soils were determined, using ion chromatography (IC) and gas chromatography–combustion–isotope ratio mass spectrometry (GC–C–IRMS). The total N and amino acid-N (AA-N), respectively, decreased by 54 % and 73 % in the period from 1929 to 1997. The average N loss was comparable for 1929–1963 (period 1) and 1963–1997 (period 2), but AA-N loss was three times faster in the former period. This significant reduction in total AA-N content was mirrored in the individual amino acids, which decreased by 74 %?±?1 % (ranging 58–89 %) between 1929 and 1997. The bulk δ¹⁵N values generally increased from 1929 to 1997, mainly associated with comparable or even higher increase of δ¹⁵N of the non-AA-N in the soil. The residence time (t _1/2, time in which half of N was lost from a specific soil pool) was ca. 65?±?5 years for the bulk soil, and comparable for periods 1 and 2. However, between periods 1 and 2 it decreased from 128 to 41 years in the non-AA pool, but increased from 59 to 92 years in the AA-N pool. Proline and amino acids that appear early in soil microbial metabolic pathways (e.g. glutamic acid, alanine, aspartic acid and valine) had relatively high δ¹⁵N values. Phenylalanine, threonine, glycine and leucine had relatively depleted δ¹⁵N values. The average δ¹⁵N value of the individual amino acids (IAAs) increased by 1δ unit from 1929 to 1997, associated with a similar rise from 1929 to 1963, and no change thereafter till 1997. However, the δ¹⁵N values of phenylalanine decreased by more than 7δ¹⁵N units between 1929 and 1997. The δ¹⁵N shift of IAAs from 1929 to 1963 and from 1929 to 1997 was not influenced by the relative amount of N remaining compared with the 1929 soil concentrations. The only exception was phenylalanine which showed decreasing δ¹⁵N associated with its decreasing concentration in the soil. We conclude therefore that in the absence of plant and fertiliser inputs, no change in the δ¹⁵N value of individual soil amino acids occurs, hence the original δ¹⁵N values are preserved and diagnostic information on past soil N (cycling) is retained. The exception was phenylalanine, its δ¹⁵N decreased with decreasing concentration from 1929 to 1997, hence it acted as a ‘potential’ marker for the land use changes (i.e. arable cropping to a fallow). The long term biological processing and reworking of residual amino acids resulted in a (partial) stabilisation in the soil, evidenced by reduced N loss and increased residence time of amino acid N during the period 1963–1997.     

Oxidation of pentan-2-ol – part II: Experimental and modeling study

The oxidation of pentan-2-ol was investigated at high-pressure in a jet-stirred reactor and in a shock tube. Experiments in the JSR were carried out at 10 atm, between 500 and 1180 K, for five different equivalence ratios of φ = 0.35, 0.5, 1, 2, 4 and 1000 ppm of fuel, at a constant residence time of 0.7 s. Reactant, product and intermediate species mole fractions were quantified using Fourier transform infrared spectrometry (FTIR) and gas chromatography (GC). Ignition delay times were measured for pentan-2-ol/O₂ mixtures in argon in a shock tube at 20 and 40 bar, in a temperature range of 1070–1460 K and for equivalence ratios of φ = 0.5, 1 and 2. Ignition delay times of a stoichiometric mixture were also measured in air at 20 bar. Under these conditions, this alcohol exhibited no low-temperature reactivity in either experimental set-ups. Based on ab initio calculations presented in the companion paper, a detailed kinetic mechanism was developed in order to reproduce the present data and analyze the reaction pathways.     

The reaction of 2,5-dimethylfuran with hydrogen atoms – An experimental and theoretical study

The kinetics of the reaction of hydrogen atoms with 2,5-dimethylfuran (25DMF), a promising liquid transport biofuel, was experimentally studied in a shock tube at temperatures between 970 and 1240 K and pressures of 1.6 and 4.8 bar. The hydrogen atoms were produced by pyrolysis of ethyl iodide and monitored by atom resonance absorption spectrometry. From the hydrogen atom concentration–time profiles, overall rate coefficients for the reaction H + 25DMF → products (R1) were inferred. The results can be expressed by the Arrhenius equation k₁ = 4.4 × 10^?11 exp(?1180 K/T) cm^?3 s^?1 with an estimated uncertainty of ±30%. A significant pressure dependence was not observed. The results were analyzed in terms of statistical rate theory with molecular and transition state data from quantum chemical calculations. Three different compound methods were used to characterize the potential energy surface: CBS-QB3, CBS-APNO, and G3. It is found that reaction (R1) mainly (>75%) proceeds via an addition–elimination mechanism to yield 2-methylfuran + CH₃. Kinetic parameters for the most important competing channels of the net reaction (R1) were calculated.     

Thermo-acoustic performance of full engine encapsulations – A numerical,experimental and psychoacoustic study

This paper presents the development and investigation of a thermo-acoustic encapsulation for a diesel engine by means of a combined approach of thermo-acoustic recordings, numerical simulations and psychoacoustic evaluation. The encapsulation is positioned in close proximity to the engine and completely surrounds the entire engine block. Experimental tests are performed with the help of an acoustic engine test bench, where the surface of the engine is observed by infrared cameras and the sound is monitored by a microphone-array. Thermal and acoustic measurements of the engine without an encapsulation are recorded and used as reference data for simulations to evaluate and improve the functionality of different design concepts of the encapsulation in comparison to the same engine without encapsulation. The received experimental results are also used to select proper materials as well as to design the heat insulating and sound absorbing encapsulation. Based on the experimental investigations, some weak points of the first prototype are identified. These experimental findings, as well as numerical simulations of the sound radiation, are used as a basis for further design improvements to the encapsulation. The new design that is developed shows a significant improvement in the insulation of the car engine, both thermally and acoustically. In the last step, the perception of the engine sounds are evaluated by measuring changes in the perceived loudness and sound preference of the engine with and without encapsulation by human participants. This allows for a more objective evaluation of the acoustic behavior of the developed engine encapsulation.     

Acoustics and new learning environment – A case study

This study presents the results of an acoustic performance evaluation of classrooms and their corridors on a test area of the Finnish Oulu Normal School. The project, “Spaces for learning and creation of new knowledge”, was organised by Rym Ltd and was a re-design pilot study where spatial analysis of some new schools and new forms of future school design have been made.     

Effects of ultrasound frequency and acoustic amplitude on the size of sonochemically active bubbles – Theoretical study

Numerical simulation of chemical reactions inside an isolated spherical bubble of oxygen has been performed for various ambient bubble radii at different frequencies and acoustic amplitudes to study the effects of these two parameters on the range of ambient radius for an active bubble in sonochemical reactions. The employed model combines the dynamic of bubble collapse with the chemical kinetics of single cavitation bubble. Results from this model were compared with some experimental results presented in the literature and good apparent trends between them were observed. The numerical calculations of this study showed that there always exists an optimal ambient bubble radius at which the production of oxidizing species at the end of the bubble collapse attained their upper limit. It was shown that the range of ambient radius for an active bubble increased with increasing acoustic amplitude and decreased with increasing ultrasound frequency. The optimal ambient radius decreased with increasing frequency. Analysis of curves showing optimal ambient radius versus acoustic amplitude for different ultrasonic frequencies indicated that for 200 and 300 kHz, the optimal ambient radius increased linearly with increasing acoustic amplitude up to 3 atm. However, slight minima of optimal radius were observed for the curves obtained at 500 and 1000 kHz.     

Crystallization Kinetics of Linear and Long‐Chain Branched Polypropylene

Isothermal crystallization kinetics of linear polypropylene (PP) and long‐chain branched (LCB) PPs were investigated on the basis of the Avrami theory. The Avrami exponents of LCB PPs are smaller than that of linear PP; moreover, they decrease with an increasing LCB level. The crystallization half‐time of LCB PP depends more strongly on the crystallization temperature than does that of linear PP. The Lauritzen‐Hoffman theory was used to study the effect of LCB on the crystal growth rate of PP. The fold surface free energy of LCB PP is lower than that of linear PP; moreover, it decreases with an increasing LCB level. However, when the LCB level is over a certain value, the fold surface free energy increases again. Furthermore, the crystal structures of linear PP and LCB PPs were studied by wide‐angle X‐ray diffraction (WAXD); it was observed that linear PP can crystallize in the α and β forms, while LCB PPs have only the α crystalline form. Moreover, the relative intensities of different α peaks were also influenced by the LCB level.     

Mechanism and kinetics of the atmospheric degradation of 2-formylcinnamaldehyde with O3 and hydroxyl OH radicals – a theoretical study

In the present investigation, the reaction mechanism and kinetics of 2-formylcinnamaldehyde (2-FC) with O₃ and hydroxyl OH radicals were studied. The reaction of 2-FC with O₃ radical are initiated by the formation of primary ozonide, whereas the reaction of 2-FC with the hydroxyl OH radical are initiated by two different ways: (1). H-atom abstraction by hydroxyl OH radical from the –CHO and –CH = CHCHO group of 2-FC (2). Hydroxyl OH addition to the –CH = CHCHO group to the ring-opened 2-FC. These reactions lead to the formation of an alkyl radical. The reaction pathways corresponding to the reactions between 2-FC with O₃ and hydroxyl OH radicals have been analysed using density functionals of B3LYP and M06-2X level of methods with the 6-31+G(d,p) basis set. Single-point energy calculations for the most favourable reactive species are determined by B3LYP/6-311++G(d,p) and CCSD(T)/6-31+G(d,p) levels of theory. From the obtained results, the hydroxyl OH addition at C8 position of 2-FC are most favourable than the C9 position of 2-FC. The subsequent reactions of the alkyl radicals, formed from the hydroxyl OH addition at C8 position, are analysed in detail. The individual and overall rate constant for the most favourable reactions are calculated by canonical variational transition theory with small-curvature tunnelling corrections over the temperature range of 278–350 K. The calculated theoretical rate constants are in good agreement with the available experimental data. The Arrhenius plot of the rate constants with the temperature are fitted and the atmospheric lifetimes of the 2-FC with hydroxyl OH radical reaction in the troposphere calculate for the first time, which can be applied to the study on the atmospheric implications. The condensed Fukui function has been verified for the most favourable reaction sites. This study can be regarded as an attempt to investigate the O₃-initiated and hydroxyl OH-initiated reaction mechanisms of 2-FC in the atmosphere.     

Quantum uncertainty and a counterexample of nonlocal classical “realism”

We analyze the scheme of an experiment in which, by examining suppression effects of the cross correlation of photons in a beamsplitter and by preparing squeezed states, it is proven that the phase difference of photons in Fock states cannot acquire a certain value, since, otherwise, the simultaneous existence of these two effects would be impossible. We show that this reveals an intrinsic inconsistency of the nonlocal classical interpretation of quantum mechanics on the basis of nonlocal classical “realism.”     

Nanodosimetry of 125I – Auger electrons – Experiment and modeling

The experiment with ¹²⁵I-Auger electrons, interacting with gaseous nitrogen with size equivalent to segment of DNA in mass per unit area scale, are described. The discrete ionization cluster-size distributions have been obtained. The shapes of which are definitely determined by the size of the interaction volumes. The volume sizes studied in the present work are comparable with a segment of DNA and of nucleosome. The experiments have been carried out with the set up, called Jet Counter, and are the first cluster-size distributions as yet measured for an Auger-electron emitter like ¹²⁵I. The experimental results have been compared with those obtained by Monte Carlo simulation. The results for ¹²⁵I have been compared with calculated cluster size distribution for ¹³¹I.     

On the phase uncertainty of Fock states and “nonlocal realism”

Based on the study of the effects of the suppression of cross-correlation of photons on a beam splitter and preparation of squeezed states, an experimental proof is proposed for the lack of determinate values of the phase and phase difference of photons in Fock states. It is shown that this conclusion unveils the intrinsic inconsistency of interpreting quantum mechanics on the basis of the nonlocal theory of hidden variables and proves the inadequacy of the latter.     

Design of ring resonator based all optical switch for logic and arithmetic operations – A theoretical study

In this paper, a general analysis for non-linear micro-ring resonator as all optical switch is discussed in a vertically coupled GaAs–AlGaAs micro-ring resonator by carrier injection. The ring resonator is optically pumped, which results in temporal shift of resonant wavelength by refractive index change due to carrier injection. A green laser as optical pump beam is used to shift resonant wavelength 1.5 nm of the ring resonator. Simulation, analysis and overall transfer function of single ring as well as cascaded micro-ring resonator (MRR) is studied. A single circuit, consisting of three MRRs, capable to perform all the two input sixteen logic operations is studied and reported. The same circuit can also act as half adder/subtractor and single bit data comparator.     

Ab initio study of PN electronic states – a qualitative interpretation of the perturbation and predissociation effects on observed transitions

Valence and high electronic states of PN have been calculated with accurate quantum chemistry methods. The variety of theoretical methods used includes complete active space self-consistent field, multireference configuration interaction and the newly developed explicitly correlated coupled cluster methods. The large correlation-consistent atomic orbitals basis sets AVQZ, AV5Z and AV(5+d)Z are used for the potential energy curves calculations in the bonding and long-range regions. The spectroscopic constants (R_e, B_e, ω_e, ω_ex_e, α_e, D_e, T_e) and the vibrational levels of the bound valence states (X¹Σ⁺, A¹Π, a³Σ⁺, d ³Δ, e³Σ^?, C¹Σ^?, b³Π, D ¹Δ and E¹Σ⁺ and some higher bound states) are determined and compared with experimental findings when available. Significant spin–orbit interactions between triplet states and A¹Π and E¹Σ⁺ excited states are found near the crossing points of the potential energy curves and could explain predissociation phenomena and the perturbations of the vibrational levels experimentally observed for PN in their A¹Π and E¹Σ⁺ states.     

Discussion on sources of uncertainty for two TLD albedo dosimetry systems in a comparison of individual monitors in a reference 241Am–Be field

Under standard conditions, several studies assess uncertainty values for individual dosimetry for photons, but seldom for neutrons. The Thermoluminescent Dosimetry Laboratory (LDT) of the Instituto de Radioproteção e Dosimetria (IRD), Brazil, has been running a neutron individual monitoring service using two different albedo monitors. This paper presents a study of the contribution of relevant sources of uncertainty for neutron dose evaluation, for both systems (called System 1 and System 2), using a reference ²⁴¹Am–Be field, at normal incidence. The combined and expanded uncertainties were calculated using GUM methodology and follows RP160 from the European Commission. This methodology was applied to calculate the uncertainties associated with the LDT assessment of neutron doses in the First Brazilian National Comparison on Measurements for Neutron Individual Monitors. The LDT participated in this comparison with its two systems, both presenting satisfactory performance. For System 1, at low neutron doses, the reproducibility of the apparent neutron dose is the more relevant source of uncertainty. However, for higher doses, the neutron calibration factor, NCF, becomes more important. For System 2, NCF is the main source of uncertainty for low and high doses. For occupational doses, the uncertainty will be much higher due to the need of additional correction factors, which depend on stray neutron field.     

Isotope fractionation of sandy-soil water during evaporation – an experimental study

Soil samples containing water with known stable isotopic compositions were prepared. The soil water was recovered by using vacuum/heat distillation. The experiments were held under different conditions to control rates of water evaporation and water recovery. Recoveries, δ¹⁸O and δ²H values of the soil water were determined. Analyses of the data using a Rayleigh distillation model indicate that under the experimental conditions only loosely bound water is extractable in cases where the recovery is smaller than 100?%. Due to isotopic exchange between vapour and remaining water in the micro channels or capillaries of the soil matrix, isotopic fractionation may take place under near-equilibrium conditions. This causes the observed relationship between δ²H and δ¹⁸O of the extracted water samples to have a slope close to 8. The results of this study may indicate that, in arid zones when soil that initially contains water dries out, the slope of the relationship between δ²H and δ¹⁸O values should be close to 8. Thus, a smaller slope, as observed by some groundwater and soil water samples in arid zones, may be caused by evaporation of water before the water has entered the unsaturated zone.     

The Influence of Ultraviolet Light on Luminescence (700–1000 nm) of LiF and LiF:OH Crystals Irradiated in a Nuclear Reactor

Optics and Spectroscopy - The emission (700–1000 nm) and absorption (200–800 nm) spectra of LiF and LiF:ОН crystals irradiated in a reactor and by UV light, as well as...     

A phase field crystal study of heterogeneous nucleation – application of the string method

We use the simplified string method in order to examine two dimensional heterogeneous nucleation at a wall and on a substrate. The material is described by a phase field crystal model and the influence of the wall or substrate is included by an external potential. Tuning the external potential we show that we can control the contact angle in equilibrium and misfit to a substrate. The nucleation barrier is reduced by a wall, but cannot be explained by classical nucleation theory due to non-classical nucleation paths. For small misfits a substrate also decreases the nucleation barrier, while large misfits increases the nucleation barrier.