Floor Properties Research Articles

Seven spruce species on a mountain site - performance, foliar nutrients, and forest floor properties in stands 20 years old

Abstract: Norway spruce is often considered to have a negative impact on a site, yet it is native to many mountain regions of Europe. The relative influence of Norway spruce on site properties has frequently been compared with that of both broadleaved and other coniferous tree species. In our study, growth, as well as needle, forest floor, and topsoil chemistry were compared between Norway spruce and introduced spruce species (white, black, red, Serbian, Sitka, and blue spruce), all growing on the same, formerly polluted mountain site. There were few differences in needle nutrient status between the introduced spruce species and native Norway spruce. The chemistry of forest floor horizons beneath some of the non-native species showed less acidity and better conditions of the soil sorption complex. There were no significant differences in the nutrient pools, indicating that the influence of the various spruce species on the site was comparable. Given the small differences observed in the various nutritional characteristics, it appears that, under the conditions of the study site, the alternative spruces had substituted for the role of Norway spruce before its recovery in the 2000s. The six spruces grew quite consistently during 2001-2012, while the mean height of Norway spruce shifted from the lowest 176 cm (2001) to one of the tallest. At 710 cm (2012), its height had become comparable with that of Sitka. The poorest performing were black spruce (due to bark beetle attack) and blue spruce (due to bud blight infestation and decline).

Parametric Energy simulation in concept design phase: A dynamic simulation case study

This paper presents a framework for the development of early-design guidance to inform architects and policy-makers using parametric whole-building energy simulation. The emphasis of the study was to identify and assess the benefit of energy efficiency alternatives primarily focused on the building’s thermal envelope. The energy efficiency alternatives included performance adjustments to the external glazing, wall, roof, floor properties. The Result indicated the glazing selection should look to achieve the highest thermal resistance (R-value) and best solar control (lowest shading co-efficient value) within budget. Ideally a solar control low-e IGU system could be installed. Solar control glazing also reduced the required development cooling capacity by ∼17%.

The effect of the concentration of steel fibres on the properties of industrial floors

Czasopismo Techniczne » 2019 » Volume 4 » The effect of the concentration of steel fibres on the properties of industrial floors A A A

2D USS of the pelvic floor in the 3rd trimester versus mode of delivery

ObjectiveBiomechanics of pelvic floor muscles is becoming an important field of research in understanding a complex process of labour. Current evidence indicates that the levator ani stretches to allow passage of the fetus through the birth canal. We sought to identify properties of the functional female pelvic floor during pregnancy that could help to predict the mode of delivery, especially in women who underwent caesarean section in the past. MethodsA single centre prospective cohort study of pregnant women in the 3rd trimester attending antenatal clinic. Participants were categorised into three groups: 1. nulliparous, 2. previous one vaginal delivery and 3. previous one caesarean section who chose a trial of labour in their current pregnancy. All women underwent ultrasonographic evaluation of their pelvic floor muscles. Distensibility and the mode of delivery were assessed in participants’ current pregnancies. The primary outcome was the mode of delivery. ANOVA test was used for statistical analysis. Results133 women were included: 55 nulliparous, 52 primiparous (previous one vaginal birth), and 26 primiparous (previous one LSCS and planned for vaginal delivery after caesarean (VBAC)). Participants were scanned at an average gestation of 32 weeks. The inter-observer reliability test for puborectalis distensibility was good (kappa 0.75).Overall, women who delivered vaginally had a more distensible puborectalis muscle than those who delivered by emergency LSCS regardless of their previous type of delivery. Women who underwent a successful VBAC had less distensible pelvic floor muscles compared to their nulliparous and primiparous counterparts (who delivered vaginally in the past). ConclusionThese results support our basic conceptual theory of puborectalis muscle distensibility influencing the mode of delivery and endorse application of dynamic pelvic floor ultrasound in future studies. We identified measurable differences in the functional female pelvic anatomy aiding a better understanding of physiology of the labour. There are trends towards lesser distensibility in women who delivered by LSCS.

Resource Heterogeneity Relationship with Understory Vegetation in Post-fire Xeric Jack Pine Forests

Xeric jack pine forests in northern boreal ecosystems are becoming more vulnerable with the increasing fire frequencies in this region. Understory vegetation is the most diverse aboveground component of this seemingly homogeneous system consisting of only jack pine in the overstory. Understanding the relationship between understory vegetation, fire severity, and resource availability is therefore necessary for managing these forests. In this study, we used spatial statistics to examine the relationship between understory vegetation and resource conditions as affected by two different pre-fire ages ( 60 years) and two fire severities (non-stand replacing fire, NRF, and stand replacing fire, SRF) in xeric jack pine forests in northern Alberta, Canada, four growing seasons post-fire. Using the same framework, we also tested the relationship between resource heterogeneity and species richness commonly known as the resource heterogeneity hypothesis. Spatial heterogeneity, that is, variability, scale of spatial dependency, and patchiness in plant functional groups (cover and richness), microsite conditions (forest floor and soil properties), and light availability were characterized using semivariograms, and their interrelationships were analyzed using spatial autoregressive models. Our findings indicated a stronger fire severity effect on the spatial properties of vegetation composition and microsite conditions than the pre-fire stand age effect. The spatial variability of microsite properties was greater in the NRF sites compared to the SRF sites, but varied in between pre-fire stand ages. Positive relationships were detected between species richness and variability of microsite properties in the NRF sites, whereas such relationships were negative in the SRF sites. Partial Mantel tests indicated a possible dependency of species richness on forest floor variability in the NRF and older sites, and on soil variability in the SRF and younger sites. Overall, findings from this study suggest that spatial heterogeneity in post-fire resource conditions influences the spatial assemblages of understory vegetation in xeric jack pine forests, and a change in fire severity might significantly alter the microsite variability and therefore the mechanisms that drive spatial patterns in understory vegetation.

In vivo assessment of the levator ani muscles using shear wave elastography: a feasibility study in women.

We hypothesized that shear wave elastography (SWE) technology might be useful for assessing the elastic properties of the pelvic floor in women. Our primary objective was to evaluate the feasibility of assessing the levator ani muscles using SWE in women. Our secondary aim was to investigate the changes in their elastic properties from rest to Valsalva maneuver. During this prospective feasibility study in nonpregnant female volunteers, we collected data on participant age, body mass index (BMI), parity, and time since the delivery. The levator ani muscles of each participant were assessed using SWE technology at rest and during a Valsalva maneuver by measuring the shear modulus (in kilopascals). We then assessed the changes in the shear modulus at rest and during the Valsalva maneuver using a Wilcoxon test. Twelve parous women participated in this study. The mean time since the last delivery was 14months, the mean age was 31years, and mean BMI was 28kg.m-2. All the assessments performed at rest were successfully completed, but we encountered two failures during the Valsalva maneuver. The mean shear modulus increased by a factor of more than 2 from rest to the Valsalva maneuver for both the right (16.0 vs 35.4kPa) and left side (17.1 vs 37.6kPa). An assessment of the elastic properties of the levator ani muscles is feasible for nonpregnant women. The reproducibility of the technique and its application in pregnant women and women with pelvic floor disorders must be investigated.

The spread of Kalmia angustifolia on black spruce forest cutovers contributes to the spatial heterogeneity of soil resources.

Kalmia angustifolia is a boreal ericaceous shrub that can rapidly spread on black spruce forest cutovers in eastern Canada, where CPRS (i.e. Cutting with Protection of Regeneration and Soils”) is practiced. The proliferation of Kalmia often coincides with a reduction in the growth rate of regenerating black spruce seedlings. We report on a study where we compared the local effects of Kalmia and black spruce seedling patches (i.e. two types of “Vegetation”) on chemical and biochemical soil properties in CPRS cutovers within mesic spruce-moss and xeric spruce-lichen ecosystems, as well as in four mature spruce-moss forests (i.e. three “Site Types”). Results from 13C-CPMAS-NMR revealed lower O-alkyl C (i.e. carbohydrates), higher aromatic C (i.e. lignin and other phenolics) and higher carbonyl-C (i.e. amide-C and carboxyl groups) in spruce-moss than in spruce-lichen forest floors (F-horizon). In spite of these distinctions, we observed only a small number of Site Type x Vegetation interactions controlling soil properties. Vegetation had a significant effect on ten forest floor properties. Most notably, Kalmia patches had higher concentrations of condensed tannins and lower mineral N cycling. On the other hand, Site Type had a relatively greater effect on the deeper podzolic-B horizons, where mineral N and microbial activity were higher in mature spruce-moss forests than in the cutovers. Green and senescent Kalmia leaves collected at these sites had higher N, tannin and phenolic concentrations than green and senescent spruce needles. A 25 month litter bag study found lower decomposition of Kalmia leaf litter in spruce patches on spruce-lichen cutovers compared to spruce patches on spruce-moss cutovers, or to Kalmia patches on spruce-lichen cutovers. Given that black spruce seedlings obtain most of their nutrients from the forest floor, our results suggest that CPRS may have long-term negative effects on black spruce forest productivity if the spread of Kalmia is left unchecked.

Experimental study of mechanical properties of lightweight composite floors

The mechanical performance of the fabricated composite floors consisting of thin-walled steel beams and lightweight aggregate concrete was experimentally studied and effect of some important factors on the mechanical properties of the composite floor specimens was discussed. The experimental results showed that the composite floors had better plastic deformation capacity, greater bearing capacity and better entirety, and effect of the geometrical construction of cross section of the main steel beams on the mechanical property of the floors was related with deformation of the floors in a degree.

Test study of mechanical properties of composite floors of thin-walled steel and ceramsite concrete

The mechanical property of the lightweight composite slabs consisting of ceramsite concrete and thin-walled steel beams was experimentally studied. The test results showed that the composite floors had larger stiffness and better entirety, the relation of load P and vertical displacement of the composite slab specimens had evident nonlinearity, but the deflection Δ varied linearly with load P for the load less than 12kN for all the lightweight composite floor specimens. It was seen that distribution of strains of cross section of main steel beams basically agreed with the plan cross-section assumption.

Effects of Mineral Soil and Forest Floor on the Regeneration of Pedunculate Oak, Beech and Red Oak

Early regeneration is a critical life stage that affects the future species composition of forests. Knowledge about regeneration success under different environmental conditions allows better understanding of forest dynamics. We studied the effects of seedbed conditions on the establishment and performance of seedlings of pedunculate oak, beech and red oak. In 50 plots of a tree-diversity oriented research platform in mature forests in northern Belgium (TREEWEB), we installed a field experiment with three treatments (potting soil, mineral soil, mineral soil + forest floor), in which we sowed seeds of each species. We monitored early establishment and survival, height, root and shoot biomass of the seedlings after two growing seasons. Mineral soil negatively affected seedling establishment and performance relative to the potting soil. The negative soil effects did not vary with measured abiotic soil properties. In general, the forest floor did not deteriorate or mitigate the soil effects, and only for root biomass did the forest floor partly compensate the negative soil effects. Forest floor effects did not vary with the measured forest floor properties. In the studied forests, creating bare soil was not enough to promote regeneration; improving soil properties might be important for the success of natural regeneration.

A Review of Research on Human-induced Vibration Serviceability and Dynamic Properties of Long-span Floor

Studies on the dynamic properties of long-span floor is an essential basis for a solution to the problem of human-induced vibration serviceability. According to the recent research, this review introduces the application of numerical simulation in the research of dynamic properties and summarizes the modeling method of sophisticated finite element model. The reliability of the finite element model is verified by the field test and model test. Comparing the application of studies on dynamic properties among numerical simulation and model test, the differences between numerical simulation and model test are summarized. Finally, some problems that need further study are proposed.

Evaluation of physical properties by inverse dynamics for various floor properties

Evaluation of physical properties by inverse dynamics for various floor properties

ATTO: Wireless Networking at Fiber Speed

ATTO targets wireless networking at fiber speed: 100 Gb/s/m2 with latencies smaller than 10 μs. To provide this tremendous wireless capacity, ultrasmall floor-integrated cells are proposed. In this way, short-reach communication can be established, reducing the effect of interference and providing full frequency reuse in the wireless domain. Radio frequency (RF)-over-fiber coherent communication and a dedicated 2-D passive optical network structure support the interconnection and selection of the cells and minimize the required transceiver electronics. To evaluate the feasibility of the proposed architecture, key principles are validated at lower frequency bands. Two main building blocks are addressed in this paper: a fully passive opto-antenna to prove that a passive remote antenna head can be realized owing to the short transmission distances. Furthermore, a low-cost RF-over-fiber system is demonstrated: sigma–delta modulation drives nonlinear optical modulators, such as electroabsorption modulators and vertical-cavity surface-emitting lasers, using a digital transmitter while remaining compatible with the passive opto-antenna. Finally, two important properties of the ATTO floor are evaluated. The exposure of a human body model to RF fields by the antenna floor is evaluated. Measurements ensure a 200-fold margin with respect to the International Commission on Non-Ionizing Radiation Protection basic restriction. To guarantee that multiple devices can communicate with the ATTO floor simultaneously, the interference between cells spaced 300 mm apart was evaluated.

Vibration of lightweight steel floor systems with occupants: Modelling, formulation and dynamic properties

Abstract Theoretical analyses are presented for investigating the vibration of lightweight steel floor systems with human occupants. A damped plate-oscillator model is proposed to obtain the dynamic properties of coupled floor-occupant systems. A generalized formulation of the damped plate-oscillator model is proposed. A complex eigenvalue analysis is performed with the use of state-space method and a validation study is conducted by comparing with other undamped plate-oscillator models. The dynamic properties obtained from the proposed model are verified by laboratory tests performed on full-scale lightweight cold-formed steel (CFS) floor systems. The influence of human occupants on the dynamic properties of lightweight steel floors are investigated in three scenarios: an unoccupied floor, a floor with one standing occupant and a floor with two standing occupants. Four human dynamical models in standing position, two with one degree of freedom (SDOF) and others with two degrees of freedom (2-DOF), are adopted in the proposed plate-oscillator model and the obtained results are compared to the test results. Comparisons are also made between the proposed plate-oscillator model with the integrated 2-DOF model for coupled floor-occupant systems. In addition, the need of recalibrating human models for lightweight floor systems is also discussed.

Review: Marine Seismic And Side-Scan Sonar Investigations For Seabed Identification With Sonar System

Marine seismic reflection data have been collected for decades and since the mid-to late- 1980s much of this data is positioned relatively accurately. Marine geophysical acquisition of data is a very expensive process with the rates regularly ship through dozens of thousands of euros per day. Acquisition of seismic profiles has the position is determined by a DGPS system and navigation is performed by Hypack and Maxview software that also gives all the offsets for the equipment employed in the survey. Examples of some projects will be described in terms of the project goals and the geophysical equipment selected for each survey and specific geophysical systems according to with the scope of work. For amplitude side scan sonar image, and in the multi-frequency system, color, becoming a significant properties of the sea floor, the effect of which is a bully needs to be fixed. The main confounding effect is due to absorption of water; geometric spread; shape beam sonar function (combined transmit-receive sonar beam intensity as a function of tilt angle obtained in this sonar reference frame); sonar vehicle roll; form and function of the seabed backscatter (proportion incident on the seabed backscattered signal to sonar as a function of the angle of incidence relative to the sea floor); and the slope of the seabed. The different angles of view are generated by the translation of the sonar, because of the discrete steps involved by the sequential pings, the angular sampling of the bottom.

Experimental Study on Vibration Properties of the Full-scale Flat-plate Floor Subjected to Fire

To further understand the fire behavior and vibration characteristic of flat-plate floor, this paper examines the results of a full-scale flat-plate floor subjected to fire. The case under experimental study models the reality of fire conditions and uses a special furnace to heat the bottom surface of the slab with ISO 834 standard fire curve. Detailed experimental data in the form of describing temperature distribution, vertical and edge horizontal deflections, failure pattern and vibration frequency are presented. The experiment results indicate that the top crack pattern is consistent with that at ambient temperature, and it can be assumed that the yield-line pattern at elevated temperatures should follow the conventional one. Frequency variation of the slab under fire obtained by FFT shows that the first vibration mode was generated, and the mechanical behavior could be distinguished as cracks rapidly emerge and develop phase, existed cracks slowly develop phase and stationary phase by the frequency variation. Frequency analysis also shows that the frequency can be expressed by the simultaneous central vertical displacement of the slab with a quadratic equation.

Effect of Walking people on Dynamic Properties of Floors

Despite the intensive research that has focused on the dynamic interaction between walking people and slender footbridges, this phenomenon has never been investigated for floor structures. For lightweight floors having mass of 150 kg/m2 or less, where they have relatively low modal masses and damping ratios, this interaction is expected to be more effective than that for normal floors. Such phenomenon, if proven to exist for floors, could explain one of the reasons behind the discrepancy between the measured vibration response of floors due to human walking and the corresponding predicted responses using the currently available models which neglect human-structure interaction for walking humans.This paper presents the first attempt to investigate the effect of walking people on the dynamic properties of floors. It is based on several experimental tests for groups of people walking on a full-scale but slender laboratory floor structure. For each experiment, a modal test was carried out to identify the dynamic properties of the tested floor. The results showed a significant increase in modal damping for the first vibration mode, while higher modes exhibited less damping increase. A slight increase was also noticed in the natural frequency of the observed modes. These changes in the modal properties are in line with previous observations of the effects of walking people on footbridges. The results presented in this paper can pave the way for future research to model the interaction between walking people and the supporting floor structures in the context of their vibration serviceability.

Geological implications of acoustic imagery of the recent seabed textures in the Eastern Harbor, Alexandria

Acoustical geophysical devices depend on sound source to transmit sound waves that reflected, diffracted or scattered off the sea bed. The frequency used by each device controls the output information that related to the sea floor properties. The present study aims to get a recent mapping of the seabed texture mostly related to acoustic imagery, sediment analysis, and video images. High resolution side scan sonar has been used for mapping the seafloor of the Eastern Harbor, Alexandria, Egypt. Four different acoustic patterns were recognized: (a) the pattern of strong backscatter related to coarse sand, (b) the pattern of weak backscatter confined to mud and fine sand, (c) patches of strong and weak backscatter and d) the pattern with isolated reflections that belong to rock outcrops and boulders. The various wavelengths of sand ripples are identifiable that depend on their wavelength and amplitude. The presence of mega ripples in the front of the main EL-Boughaz outlet at the middle of Eastern Harbor indicates bed load transport of sediment during high energy conditions (storms). The current action on the sea bottom produced current ripples which are either straight or sinus. They are usually irregular-crested, showing no bifurcation.

Improvement of Mechanical Properties of Wood-Plastic Composite Floors Based on the Optimum Structural Design

A study is carried out on the structural design of wood-plastic composite floors. The geometric parameters of the cavities, the structure, and the means to optimize the performance of these light boards are investigated. Various structural parameters of the boards, such as size, shape, and the pattern of cavities are also studied. The optimal structure can be determined by calculation and analysis of the strength, stiffness, weight and cost of the material. A finite element model for the mechanical analysis of wood-plastic composite floors is established; and the results are used to verify the strength criteria under bending deformation, which is the most common loading condition of flooring board.

Patterns of carbon, nitrogen and phosphorus dynamics in decomposing wood blocks in Canadian forests

We measured changes in mass and in carbon (C), nitrogen (N) and phosphorus (P) concentrations and content of surface-placed and buried wood blocks decomposing over 12 years at 21 sites across Canada to evaluate the influence of the environment on C, N, and P dynamics. Carbon decomposition over time was best described using a sigmoidal fit, which was slightly better than a negative exponential function. Decomposition was slow at cold and wetland sites, with less than 15 % of the original C content lost after 12 years for 4 upland and 3 wetland sites. Decomposition rates were faster for buried than for surface blocks, except in wetlands and in a few upland sites that had high annual precipitation. Nitrogen was gained during the early stages of decomposition, followed by a net N loss once an average C:N mass ratio of 165 was reached for all upland surface-placed blocks, and 200 for upland buried blocks. Critical C:N values were weakly correlated with C:N ratios in the surface organic horizon, suggesting an influence of forest floor properties on decomposition dynamics with N release occurring sooner on more fertile sites. Critical values for N and P mineralization were greater than those reported for foliar litters.