Low Floor Research Articles

Effects of impact loads on heated-and-cooled reinforced concrete slabs

The potential collapse of heavy components in fires can cause dynamic loads on slabs triggering a progressive collapse of weakened slabs on lower floors. In this study, three reinforced concrete (RC) slabs heated under ISO-834 standard fire for 30, 45, and 60 min, while one slab used as a control specimen. The effects of impact loads due to the falling weight were studied using the low-velocity impact test on RC slabs. The acceleration of midspans is recorded, and the dominant frequency and crack pattern of the specimens are measured. The experimental results used to verify the finite element (FE) models. A set of parametric studies are conducted to evaluate the peak acceleration, maximum and residual displacement, load, stiffness, and absorbed energy of heated RC slabs. The outcomes of the parametric study are fed into a machine learning model called Multilayer perceptron (MLP). Results showed that the fire duration affects and reduces the peak acceleration and frequency of the slabs. The average reduction for peak acceleration was 23% for all tested slabs. Numerical results revealed that the impact load with a low energy (i.e., low mass and the height of drop) has a weak dependency on the time of exposure and reinforcement ratio. The results of this paper impact the fire safety design of the RC slabs and the evaluations of fire-exposed RC slabs.

An holistic approach to product evaluation and selection in industrialised building: Benchmarking of long span, low carbon floor systems

As the construction industry shifts towards more systematised methods of designing and delivering buildings, data-informed approaches towards product development, evaluation, and selection promise to enable improved performance (structural, acoustic, fire, environmental), material efficiencies, and ease of production while maintaining the highest quality end result. This paper presents the outcomes of an applied research project that takes the first steps towards the development of a framework to guide holistic evaluation of product performance and future design efforts. Key outcomes of the research include: a systems matrix approach to (1) map the current product landscape, (2) select representative systems for benchmarking, and (3) to communicate relative performance; and a decision matrix used to illustrate the effect of varying priorities when selecting products for use in a building project.

Experimental study on flexural behavior of box floors with orthogonal rib beams made of poplar laminated veneer lumber

This study examined the flexural behavior of the poplar laminated veneer lumber (LVL) box floor with orthogonal rib beams. Four 3.6 m × 4.8 m box floor samples made of poplar LVL orthogonal rib beams and oriented strand board (OSB) plates were tested under vertical uniform loading, from which the bearing capacity, stiffness, and failure characteristics were analyzed. There was no damage in all box floor samples at the normal service load of 2.5 kN/m2, and the maximum deflection was far less than the allowable value. When the maximum load was applied, the load-displacement curve of each floor sample exhibited a linear relationship without obvious failure. However, localized failure was manifested as the dislocation slip of the rib beams relative to the upper and lower floor slabs at the corner nodes and the joint expansion and staggered floors at the bottom plate, with obvious failure signs. The rib beam height had the most significant impact on the floor stiffness, followed by the spacing of short-side rib beams, whereas the OSB plate thickness had lest impact. The mid-span deflections of poplar LVL orthogonal ribbed box floor samples, which were calculated using the analog slab method, were in good agreement with the experimental results with an error being less than 10%.

Potential ecological and health risks of heavy metals for indoor and corresponding outdoor dust in Hefei, Central China.

The harm caused by indoor dust has received increasing attention in recent years. However, current studies have ignored comparisons with the corresponding outdoor dust. This study aimed to investigate the distribution of heavy metals in indoor and corresponding outdoor dust and the ecological and health risks they pose in Hefei, Central China. We analyzed O/I (outdoor/indoor concentration ratios) values, background comparison, and correlation analysis (heavy metal concentrations vs. particle size) and found that Cu, Zn, and Cd mainly existed in indoor sources, while V, Co, and As mainly existed in outdoor sources, and both family sizes and floor number influenced the variation of O/I. Through a new potential ecological risk assessment method, we determined that Cd risk levels in indoor and outdoor dust were extreme and high to extreme, respectively. Additionally, the carcinogenic risks of Ni, As, and Cr were not negligible. The risk of indoor dust was higher than that of outdoor dust for the heavy metals studied, implying a poor indoor environment. Notably, indoor dust from families with smaller sizes, lower floors, and smokers had higher ecological and carcinogenic risks.

Focus on lasers, imaging, microscopy, and photonics

Focus on lasers, imaging, microscopy, and photonics

Carbon price floors and low-carbon investment: A survey of German firms

Introducing a price floor in emissions trading schemes (ETS) theoretically stabilizes expectations on future carbon prices and thus fosters low-carbon investment. Yet, ex post evidence on high carbon prices is scant and the relevance of carbon pricing for investment decisions is frequently contested. We provide empirical ex ante evidence on how a price floor in the EU ETS would impact the size and portfolio of energy firms’ investments. Analyzing survey responses of high-level managers in 113 German energy and industry companies, we find that the level of the price floor is crucial. A low price floor trajectory only provides insurance against downward price fluctuations and would leave investments largely unchanged except for industries receiving electricity price compensation, which reduce their investments. A high floor, significantly increasing the price level beyond current expectations, leads to higher investment by the majority of firms, especially by green firms, while investment in fossil energy would partially be abolished. Our studies implies that price floors can be important design components of ETS. However, policymakers need to ensure that they are at sufficiently high levels to affect investment decisions in a meaningful way.

Impacts of storey number of buildings on solar chimney performance: A theoretical and numerical approach

Under the fact that solar chimney was less investigated in multi-storey buildings, a theoretical model was then developed for solar chimney-induced buoyancy-driven natural ventilation. This is the first study addressing the influences of the storey number on ventilation rates for multi-storey solar chimney (SC) buildings. A storey correction coefficient was proposed to predict the SC-induced ventilation at various floors with identical air inlet areas. The theoretical model was established to elucidate the relationship among ventilation flow rates, solar radiation intensity, vent sizes and storey number (f), where the numerical results have also been validated. Although the total SC ventilation performance is enhanced, its enhancement with a higher chimney cavity was less effective when compared to those solar chimneys in single-storey buildings. This is due to the higher chimney cavity hindering the ventilation performance of the lower floors. The volume flow rate decreased exponentially for the top floors of each building when the two-storey building increased to a seven-storey building. For buildings with more than three storeys, the overall volume flow rate was more sensitive to the cavity gap than the solar radiation intensity, with an improvement in ventilation by 45.6% compared to 26.0% under the same conditions, respectively. To maximize the total flow rate, the optimal cavity gap should increase gradually from 0.2 m to 1.5 m for single-to seven-storey buildings. The findings of this study contribute to a further application of solar chimneys in multi-storey buildings.

Changes in Oral Microbial Diversity in a Piglet Model of Traumatic Brain Injury.

Dynamic changes in the oral microbiome have gained attention due to their potential diagnostic role in neurological diseases such as Alzheimer’s disease and Parkinson’s disease. Traumatic brain injury (TBI) is a leading cause of death and disability in the United States, but no studies have examined the changes in oral microbiome during the acute stage of TBI using a clinically translational pig model. Crossbred piglets (4–5 weeks old, male) underwent either a controlled cortical impact (TBI, n = 6) or sham surgery (sham, n = 6). The oral microbiome parameters were quantified from the upper and lower gingiva, both buccal mucosa, and floor of the mouth pre-surgery and 1, 3, and 7 days post-surgery (PS) using the 16S rRNA gene. Faith’s phylogenetic diversity was significantly lower in the TBI piglets at 7 days PS compared to those of sham, and beta diversity at 1, 3, and 7 days PS was significantly different between TBI and sham piglets. However, no significant changes in the taxonomic composition of the oral microbiome were observed following TBI compared to sham. Further studies are needed to investigate the potential diagnostic role of the oral microbiome during the chronic stage of TBI with a larger number of subjects.

Ultra-high-resolution quanta image sensor with reliable photon-number-resolving and high dynamic range capabilities

Superior low-light and high dynamic range (HDR) imaging performance with ultra-high pixel resolution are widely sought after in the imaging world. The quanta image sensor (QIS) concept was proposed in 2005 as the next paradigm in solid-state image sensors after charge coupled devices (CCD) and complementary metal oxide semiconductor (CMOS) active pixel sensors. This next-generation image sensor would contain hundreds of millions to billions of small pixels with photon-number-resolving and HDR capabilities, providing superior imaging performance over CCD and conventional CMOS sensors. In this article, we present a 163 megapixel QIS that enables both reliable photon-number-resolving and high dynamic range imaging in a single device. This is the highest pixel resolution ever reported among low-noise image sensors with photon-number-resolving capability. This QIS was fabricated with a standard, state-of-the-art CMOS process with 2-layer wafer stacking and backside illumination. Reliable photon-number-resolving is demonstrated with an average read noise of 0.35 e- rms at room temperature operation, enabling industry leading low-light imaging performance. Additionally, a dynamic range of 95 dB is realized due to the extremely low noise floor and an extended full-well capacity of 20k e-. The design, operating principles, experimental results, and imaging performance of this QIS device are discussed.

ORAL MUCOCELES: A MULTI-INSTITUTIONAL STUDY OF 1901 CASES FROM BRAZIL

<h3>Objectives</h3> To report the clinicopathologic features of a large series of oral mucoceles from Brazil. <h3>Study Design</h3> A retrospective descriptive cross-sectional study was performed. A total of 43,754 biopsy records of oral and maxillofacial lesions from 4 pathology services in Brazil were analyzed. All cases of oral mucoceles were reviewed, and clinical and demographic data were collected. <h3>Results</h3> The study comprised 1002 females (56.2%) and 782 males (43.8%) with a mean age of 19.8 ± 16.4 years (range, 01-87 years). The lower lip (<i>n</i> = 1,160, 67.4%) and floor of mouth (<i>n</i> = 172, 10.0%) were the most common affected sites, presenting clinically as nodules (<i>n</i> = 978, 79.4%) with a smooth surface (<i>n</i> = 428, 77.5%) and normal color (<i>n</i> = 768, 46.7%). Excisional biopsy was the treatment in most cases (<i>n</i> = 1392, 78.0%). Recurrent oral mucoceles represented 6.2% of all diagnosed cases (<i>n</i> = 117). <h3>Conclusions</h3> Our results confirm the findings of previous studies regarding the major clinical features of oral mucoceles. Mucoceles are lesions commonly seen in oral pathology and oral medicine services, mainly affecting the lower lip of children and young adults.

Ceiling displacement ventilation system in an experimental theatre: A method to optimize thermal comfort

Compared to traditional theatres, experimental theatres have a lower floor height and the lights are closer to the audience. The large vertical temperature gradient caused by the underfloor air distribution (UFAD) system extremely impairs thermal comfort. Thus, an improved method by introducing the ceiling displacement ventilation (CDV) system was evaluated. CFD models of the experimental theatre were established and verified by field tests. The influence of designing and operation parameters of the CDV systems on thermal comfort was investigated. Effects on energy consumption and air quality were also analyzed to improve application feasibility. The results indicated that the increment of air temperature at the audience head (AHA temperature) was reduced by 51.0% with the help of the CDV system. Thermal comfort was improved as the installation height was extended higher. Furthermore, under constant total air supply rate, the AHA temperature of the last row was decreased with the increase in the air supply ratio of the UFAD to CDV systems (RUtoC), and the total power consumption was declined by 3.1% through adjusting RUtoC compared to the traditional UFAD system. Additionally, the air quality could be significantly improved. The results are helpful to the design and operation of HVAC systems in experimental theatres.

Comparative Study of Seismic Analysis of Multi- Story Buildings with Floating Columns on Differential Positions and Floors in ZONE IV and ZONE V

Abstract: In urban area nowadays commercial as well as residential buildings on its lower floors require large spaces for banquet hall, malls, parking area and for other amenities. For fulfilling these requirements floating columns are generally provided to gain ample space in building structure. As per IS Code 1893:2016 clause no-7.1. The criteria of providing floating column is prohibited, but there is no limitation and restriction for research work. This study highlights the seismic response of a building and to analyze the structure in which there will be less damages to the structure with the presence of the floating column. This study features the significance of unequivocally perceiving the presence of the drifting section in the examination of building. It deals with the software model which validate with literature studies with RC G+12 building model in seismic zone IV and V with different case studies and floating column is provided in columns exterior, interior and core columns consequently. Time history analysis method for seismic analysis of models, various seismic parameters such as time histor of floor displacement, inter storey drift, base shear, overturning moment are compared to find out the most optimized solution. An Evaluation package of ETABS 2016 has been utilized for analyzing the above Building Structure. To keep away from unfriendly impact of seismic power, substitute measures, including firmness equilibrium of the main story and the story above, are proposed to lessen the abnormality presented by the drifting sections by concentrating on various utilization of appropriate technique.

Exploration of atom probe tomography at sub-10K

The operating temperature is a critical parameter in atom probe tomography experiments. It affects the spatial precision, mass resolving power and other key aspects of the field-evaporation process. Current commercially available atom probes operate at a minimum temperature of ∼25 K when measured at the specimen. In this paper, we explore and implement changes to the mechanical design of both the LEAPⓇ and EIKOS™ atom probe microscope systems manufactured by CAMECAⓇ to enable a specimen temperature in the sub-10 K regime. We use these modified instruments to analyze four materials systems: pure Al (in both pulsed-voltage and pulsed-laser mode), pure W (pulsed-voltage mode only), doped Si, and GaN (pulsed-laser mode only). The effects of conducting atom probe experiments in the sub-10 K regime were assessed with reference to a range of quantitative analysis metrics related to spatial precision, mass resolving power, stoichiometry and charge-state ratio. We demonstrate that the spatial precision is significantly improved with decreasing temperature, whilst the effect on mass resolving power is relatively minor. The enhanced spatial precision is significant insofar as it enables lattice planes from the doped Si samples to be resolved. Furthermore, mass spectral analysis, lower noise floors and changes in the field evaporation process enabled more accurate GaN compositional measurements. We discuss the significance of these findings for the semiconductor and metallurgical industries and the potential opportunities for further investigations of this parameter space.

Sensing optical phase distortion via beatnote detection of a dual probe beam encoded with orbital angular momentum.

Laser based optical applications such as imaging, ranging, and wireless communications are susceptible to environmental distortions. Inferring the strength of these optical distortions is crucial to obtaining information about the environment in which the system is operating. Our technique of inferring environmental distortion strength leverages the spreading of light's orbital angular momentum (OAM) spectrum combined with heterodyne detection. A laser encoded with OAM can be decomposed into a basis set of helical modes that spreads upon interaction with optical distortions. This mode spreading is quantified using the OAM spectrum that can be measured using mode projection or mode sorting techniques. This new technique, to the best of our knowledge, provides benefits compared to the latter two OAM detection methods such as: low-frequency noise rejection, a simpler optical receiver, lower noise floor, and an inherent optical phase component. Central to the method is the heterodyne detection of the zeroth-order OAM coefficient of a superimposed two-beam, two-frequency, probe. The measured heterodyne signal power is seen to be proportional to the coupling power of each beam's OAM spectra. To test the idea, wave-optic simulations and experiments using spatial light modulators are implemented using a simplified optical turbulence model to represent the environment. The experimental implementation agrees well with simulated and theoretical results.

Seismic overturning fragility analysis for freestanding building contents subjected to horizontal bidirectional floor motions

The rocking response of freestanding building contents simplified as rigid bodies was usually investigated in two dimensions with ground motions as the input, while their three-dimensional (3-D) rocking response subjected to horizontal bidirectional floor motions needs further investigation in both deterministic and probabilistic views. In this paper, the rocking response of freestanding 3-D rectangular blocks subjected to seismic excitations with two horizontal components are first investigated by shake table tests and finite element (FE) numerical simulation. An incremental dynamic analysis-based overturning fragility assessment method for the blocks within a building subjected to bidirectional ground motions is then proposed, using uncoupled nonlinear FE models of the block-building systems. The overturning fragility of six blocks within a four-story reinforced concrete frame structure is assessed. The influence of excitation directions, floor levels, block slenderness ratios (2.5, 3, 3.5 and 4), block sizes (size parameters of 91 mm, 182 mm and 364 mm) and intensity measurements (IMs) on the overturning fragility of the block is characterized. The experimental overturning fragility curves of three blocks in real conditions under bidirectional seismic excitations are finally obtained from the shake table tests. Rocking-torsional rotations are observed for the block with sliding not allowed. The block rocks around a side or a vertex while overturns around a side. Except the largest block, the block under bidirectional excitations is usually more and sometimes equally vulnerable to overturn in comparison to that under unidirectional excitations. The block on a higher floor is found to be more vulnerable to overturn than that on a lower floor considering the peak ground acceleration-based IM. These observations highlight on the significance of 3-D analysis for the rocking blocks considering floor acceleration amplification. This paper also enlarges the experimental database of seismic rocking response of rectangular blocks under bidirectional horizontal motions.

Study Performance of Floating Columns Subjected to Vertical Loads

In many cases, we need large areas in the building that are free of columns, especially on the lower floors, such as the ground floor and the basement, in order to use them as car parking or otherwise. The load path will change and new terms will appear, including the term "floating column", which is the column above the removed column, and the term “Transfer beam”, which is the beam on which the floating column is based it as a concentrated load and then transfers the loads to the adjacent columns. In this paper, the effect of vertical load on a concrete building containing a floating column has been studied and compared to another one without a floating column. Also, the results of the transfer beam were compared in a number of parameters such as moment, shear force, and deflection. A building consisting of G+4 was studied and analyzed using ETABS and Midas programs, A number of results were reached, the most important is the concept of load path redistribution, also this paper concluded that in normal buildings case all beams have an approximately equal result of bending, shear, and deflection but in floating column building the beams above the transfer beam have different values which decrease when going upward.

EFFECT OF DEFLECTION ON EVALUATION OF WALKING VIBRATION OF LONG-SPAN TIMBER FLOOR FROM THE VIEWPOINT OF HABITABILITY

Walking vibration can cause complaints to building users, especially on timber floor. In previous studies, there is a difference in the human evaluation for the same vibration between the sensory test result using the shaking table and the sensory test result using the timber full-scale test floor. In this study, the factor of this difference was investigated, and it was revealed that the deflection due to the landing of the foot influences to the evaluation of the lower rigidity timber floor. Finally, adding the deflection effect, the correction method for the previous evaluation method of walking vibration was presented.

The Bhagavad-Gītā: A Critical Introduction ed. by Ithamar Theodor

Reviewed by: The Bhagavad-Gītā: A Critical Introduction ed. by Ithamar Theodor Keya Maitra (bio) The Bhagavad-Gītā: A Critical Introduction. Edited by Ithamar Theodor. London: Routledge, 2020. Pp. xix+ 172. Paper $39.16, ISBN 978-0-367556-37-2. Bhagavad-gītā: A Critical Introduction is a collection of ten original chapters authored by nine scholars of the Gītā. While no single theme runs through all the chapters, they all revolve around the hermeneutics of the Gītā, especially in the exegetical and commentarial traditions. The first three chapters focus on the questions of structure of the text, both in terms of its organizational form and the coherence of its content. Chapters 4 through 6 focus on the Gītā's commentarial and exegetical history especially within the Vaiṣṇava tradition. Chapters 7 through 9 focus on the socio-religious and cultural impacts of the Gītā that expand the scope of its influences. Finally, chapter 10 brings the focus back to structure by its innovative proposal that the epithet "Acyuta" which Arjuna uses to refer to Kṛṣṇa at three critical junctures of the text functions to frame the structure of Arjuna's journey in the Gītā. In the process of delineating these themes, novel metaphors are introduced, longstanding scholarly conjectures are challenged, and refreshing framings are proposed. Ithamar Theodor, the editor of the volume as well as the author of the first two chapters, identifies "the discussion of the Gītā's structure" as the central theme of the opening chapters (p. xiii). He uses his metaphor of a "three-story house" to capture what he takes to be the Gītā's "three-tier concept of reality intertwined with a transformational ethical ladder" (p. 17). While the lower floor of Theodor's three-story house contains the human life of our everyday experience, the intermediary second floor supports one's efforts to relinquish worldly life to seek the state of liberation. And the topmost third floor "represents full absorption in the liberated state" (p. 18). Further, Theodor imagines this house to feature a ladder guiding its residents from the first floor to the second, and from the second to the third, thus capturing his hermeneutical quest for simplicity, coherence, and consistency in the Gītā. Theodor uses the imagery of a ladder's structure not only to describe the Gītā's textual organization but also the structure of some of its central concepts such as the three yogas and guṇas. As he writes, "The Bhagavad-gītā suggests a gradual elevation, by which one raises oneself from a lower guṇa to a higher [End Page 1] one…when one adheres to dharma by being motivated by some ulterior motives, one is considered to be governed by the two lower guṇas, but when one is able to rise to the guṇa of goodness, one practices following dharma for its own sake, in a disinterested manner, with no desire for its fruit" (p. 9). I find this use of the ladder structure in the context of guṇas problematic. Following the Gītā's conceptual scheme, we might take the guṇas to constitute everything and, further, to constitute the nature of a person such that their caste assignment determines the appropriateness of certain duties. Then the way one performs one's duties--i.e., whether "being motivated by some ulterior motives" (p. 9), or for the sake of the dharma--cannot be a matter of climbing the ladder of the guṇas. Offering an account of the uninterrupted significance of the Gītā for the Hindu philosophical and religious traditions by engaging with its exegetical history, Sharma's "Bhagavad-gītā: Its Philosophy and Interpretation" argues against two diachronic perceptions popular in the Gītā scholarship. First is the interpretation of the Bhagavad-gītā as a "source text of jñāna-yoga (through Śaṅkara in ancient India), of bhakti-yoga (through Rāmānuja in medieval India) and finally of karma-yoga (through B.G. Tilak in modern India)" as succeeding each other diachronically (p. 41). This is a popular...

Lithostratigraphy, chronostratigraphy, and sedimentary environments of the middle Miocene Quebrada Honda Basin in southern Bolivia and implications for Andean climate and uplift

The late middle Miocene Quebrada Honda Basin of southern Bolivia has long been studied for its diverse fossils of terrestrial vertebrates and, more recently, for its record of paleoelevation and paleoclimate in the Eastern Cordillera of the Andes Mountains. This paleobiological and paleoenvironmental archive is constrained by high resolution radioisotopic ages linked to paleomagnetic reversal stratigraphy in multiple areas within the basin. Nevertheless, studies of the basin's stratigraphy have been limited and questions remain about how the sedimentary deposits and fossil horizons in different parts of the basin relate to each other. We confirm the identification of three lithostratigraphic units, show that the units extend across the basin, and examine the distribution of sedimentary and pedogenic facies and volcanic tuffs within them. We identify different styles and stages of pedogenic development that correspond to mappable differences in outcrop character. Volcanic tuffs and sedimentary and pedogenic facies exhibit high lateral continuity consistent with accumulation on a low relief basin floor. In contrast, sedimentary and pedogenic features change vertically over multiple scales reflecting secular variations in aridity and stability over seasonal to multimillennial scales. Erosional truncation of lithostratigraphic units and a ~ 700,000-year gap in the ages of superimposed strata delineate an erosional unconformity with >50 m of relief that was cut ~12 million years ago. Breach of the basin margin along a boundary between local structural blocks may account for the development of localized incision during a period when landscapes of the Eastern Cordillera were stable with little deformation or erosion. Regional landscape stability at that time has been attributed to low elevation or a position behind an orographic precipitation barrier. The sedimentary and pedogenic facies, faunal communities, and intraformational unconformity of the Quebrada Honda Basin favor a low elevation setting, which has implications for the timing and mechanisms of uplift of the Bolivian Andes.

Evaluation Study of Characteristics of Balita on Acute Respiratory Infection Disease

Acute Respiratory Infections (ARI) are one of the most occurrent diseases in the Community Health Center (Puskesmas) of AlueSungai Pinang of JeumpaSubdistrict of Southwest Aceh Regency. There were 80 cases (40.0%) happening in 2015, which then experienced an increase to 138 (87.1%) cases in 2016.The purpose of this study is to find out the correlation between low birth weight (LBW), nutritional status, exclusive breastfeeding, immunization status, ventilation, floor type, and exposure to cigarette smoke towards the occurrence of ARI. This study is an observational analytic study with a case-control study design. The data collection techniques of this study were questionnaires, observation and documentation. The population of this study is 138 toddlers which then being selected with Slovin formula using purposive sampling technique with a total sample of 58 cases and 58 controls. It was obtained from the results of this study that the correlation between the occurrence of ARI and LBW (p-value = 0.000 OR = 13.429); nutritional status (p-value = 0.000 OR = 12.248); The conclusion of this study is that there is a correlation between LBW, nutritional status, exclusive breastfeeding, immunization status, ventilation, floor type and exposure to cigarette smoke towards the occurrence of ARI in under-fives at the Puskesmas of Alue Sungai of Jeumpa, Southwest Aceh Regency. It is expected that the Puskesmas of Alue Sungai Pinang provides a periodic education on the impact and causes of ARI as well as improvesgood nutritional and complete immunization status, and exclusive breastfeeding to the community.