60419 research outputs found
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A primary school driven initiative to influence commuting style for dropping-off and picking-up of pupils
No full textThe use of cars for drop-off and pick-up of pupils from schools is a potential cause of pollution hotspots at school premises. Employing a joint execution of smart sensing technology and citizen science approach, a primary school took an initiative to co-design a study with local community and researchers to generate data and provide information to understand the impact on pollution levels and identify possible mitigation measures. This study was aimed to assess the hotspots of vehicle-generated particulate matter ≤2.5 μm (PM2.5) and ≤ 10 μm (PM10) at defined drop-off/pick-up points and its ingress into a nearby naturally ventilated primary school classroom. Five different locations were selected inside school premises for measurements during two peak hours: morning (MP; 0730-0930 h; local time) and evening (EP; 1400-1600 h) peak hours, and off-peak (OP; 1100-1300 h) hours for comparison. These represent PM measurements at the main road, pick-up point at the adjoining road, drop-off point, a classroom, and the school playground. Additional measurements of carbon dioxide (CO2) were taken simultaneously inside and outside (drop-off point) the classroom to understand its build-up and ingress of outdoor PM. The results indicate nearly a three-fold increase in the concentrations of fine particles (PM2.5) during drop-off hours compared to off-peak hours indicated the dominant contribution of car queuing in the school premises. Coarse particles (PM2.5–10) were prevalent in the school playground, while the contribution of fine particles as a result of traffic congestion became more pronounced during drop-off hours. In the naturally ventilated classroom, the changes in indoor PM2.5 concentrations during both peak hours (0.58 < R2 < 0.67) were followed by the outdoor concentration at the drop-off point. This initiative resulted in valuable information that might be used to influence school commuting style and raise other important issues such as the generally fairly high PM2.5 concentrations in the playground and future classroom ventilation plans
Deep Learning-Aided Finite-Capacity Fronthaul Cell-Free Massive MIMO with Zero Forcing
No full textWe consider a cell-free massive multiple-input
multiple-output (MIMO) system where the channel estimates and
the received signals are quantized at the access points (APs)
and forwarded to a central processing unit (CPU). Zero-forcing
technique is used at the CPU to detect the signals transmitted
from all users.. To solve the non-convex sum rate maximization
problem, a heuristic sub-optimal scheme is proposed to convert
the problem into a geometric programme (GP). Exploiting a deep
convolutional neural network (DCNN) allows us to determine
both a mapping from the large-scale fading (LSF) coefficients
and the optimal power by solving the optimization problem
using the quantized channel. Depending on how the optimization
problem is solved, different power control schemes are investigated;
i) small-scale fading (SSF)-based power control; ii) LSF
use-and-then-forget (UatF)-based power control; and iii) LSF
deep learning (DL)-based power control. The SSF-based power
control scheme needs to be solved for each coherence interval
of the SSF, which is practically impossible in real time systems.
Numerical results reveal that the proposed LSF-DL-based scheme
significantly increases the performance compared to the practical
and well-known LSF-UatF-based power control, thanks to the
mapping obtained using DCNN
‘Business Code/Spaces’ in digital service firms: The case of online multinational fashion retailing
No full textThe impacts of digital technology on the spaces and practices of firms are of increasing concern, yet we know comparatively little about how emerging digital business models affect the ‘business spaces’ of service firms. We draw on case study research within five leading online fashion retailers to identify interweaving virtual and physical spaces of online retailing that are expressed through intra- and inter-firm digital interdependency management. This allows us to build a conceptualisation of the ‘business code/spaces’ of digital service firms, i.e., the entanglements between virtual, information-rich and responsive networked infrastructures, and materially and socially situated infrastructures. The conceptualisation of ‘business code/spaces’ reveals how combinations of embedded interpersonal decision-making within office-based work communities, networked partners, their established processes and bureaucracies, as well as the physical restrictions of space and place together reproduce spatial fixes and local–global geographies, but in ways fundamentally defined by digital technologies and business models. Our conceptualisation of ‘business code/spaces’, therefore, contributes to research examining the inter-relationships between ‘the digital’ and business practices as well as work concerning global retailing
An investigation into the arching action behaviour of part restrained concrete bridge deck slabs.
No full textIt is over a century ago that testing of reinforced concrete slabs by the pioneers of this form of construction such as Lord, Turner and Maillart showed that restrained slabs could carry significant loads. Since that time the interest in and knowledge of the internal arching, or compressive membrane action, that enhances the strength of reinforced concrete, has waxed and waned. The current generation of Eurocodes do not mention or specifically consider compressive membrane action. In this thesis a review of the key 20th century research, theory and testing is critically discussed, with particular emphasis on aspects related to bridge decks. The limitations and validity of the tests, particularly the use of small-scale tests, are noted. Current theories, which can be over complex, are also reviewed. It is also noted that all theory and most tests consider the ultimate limit state only; there is limited information on serviceability issues of compressive membrane action. The more recent advances in compressive membrane action and punching shear in the 21st century is also outlined. The two main codes of practice that specifically allow the use of compressive membrane action, the American AASHTO (2007) standard and the UK CD360 Standard (HE, 2017) are compared. The limitations of these codes are outlined
Whilst there are over a thousand tests in which compressive membrane action may be present have been carried out over the last 100 years not all of the tests are useful towards assessing the contribution of compressive membrane action. As part of this research project a database of test data for structures in which compressive membrane action have influenced load capacity was collected and analysed rigorously. Based on recent work on interpretation of databases for code drafting, a simple set of criteria for evaluating the usefulness and consistency of the test data is proposed. An analysis of test data was carried out and compared with theoretical results and current AASHTO, CD360 and Eurocode requirements. The data was firstly presented graphically in ways seen previously in the literature; however, the number of data points is significantly increased from previous publications. Subsequently the data was refined and presented as part of a multi-dimensional interaction limit, to outline new insights.
In the Eurocodes non-linear methods of analysis are accepted, finite element analysis is one way to carry out the non-linear analysis. Non-linear finite element analyses of partially restrained concrete slab strips under static loads were carried out to investigate behaviour in both bending and compressive membrane action. One of the drawbacks of non-linear finite element analyses is the number of parameters involved in obtaining a solution, and how to systematically define them. The material parameters of the Damaged Plasticity model within the ABAQUS program were defined systematically. A number of differing assumptions were made for the material parameters, and the effects of the variations assessed. The finite element method was used to fill in some of the gaps identified in the test database for unreinforced (plain) and reinforced concrete slab strips. The NL-FEA was then used to compare slab strips and one-way spanning slabs. The predictive capability and limitations of the calibrated model was outlined by simulating further slabs with different material properties and restraints under static line loads. The finite element models were validated against published test results shown to be of good quality by the database analysis. It was shown that the strains and rotations from the analysis can also be used to estimate shear capacity using the critical shear crack theory (Muttoni, 2008).
The observations from the existing theoretical approaches (McDowell, et al., 1956; Christiansen, 1963; Park, 1964; Eyre, 1997; and Rankin and Long, 1997), the test database and finite element analyses were brought together towards the development of a novel 3-phase analysis that considers both the serviceability and ultimate limit states. The method considers an initial un-cracked phase; a cracked phase and a final reinforcement yielding phase. The first phase is a conventional elastic analysis. For the second phase, at the serviceability limit state, the use of an arching geometry method or a new effective strain method is proposed. A validation of the methods against the test data and verification with non-linear finite element analyses were carried out. For phase-3 some improvements or refinements to the Rankin and Long (1997) strut method as a strut and tie analysis based on the results of the non-linear finite element analyses and consideration of shear and rotational limits not defined by existing theories is proposed. The applicability of the proposed 3-phase method demonstrated for the analysis of slab strips, 1-way slabs and more complex beam and slab bridges.
The majority of existing theory, tests and finite element analysis concentrate on local effects. In bridge structures both local and global effects need to be considered. The interaction of local and global effects was investigated using the 3-phase method, confirming their importance. The existing knowledge and additional findings about compressive membrane action from this thesis are brought together to consider the requirements for a tentative Annex to the Eurocodes, to allow a safe and systematic use of compressive membrane action
Quality Growth: From Process to Product Innovation along the Path of Development
No full textWe propose a demand-driven growth theory where process innovations and product innovations fulfil sequential roles along the growth path. Process innovations must initially set
the economy on a positive growth path. However, process innovations alone cannot fuel
growth forever, as their benefits display an inherent tendency to wane. Product innovations are therefore also needed for the economy to keep growing in the long run. When the
economy fails to switch from a growth regime steered by process innovation to one driven
by product innovation, R&D effort and growth will eventually come to a halt. However,
when the switch to a product innovation growth regime does take place, a virtuous circle
gets ignited. This happens because product innovation effort not only keeps growth alive
when incentives to undertake process innovation diminish, but it also regenerates profit
prospects from further process innovation effort
Long‐Term Exposure to Air Pollution and Risk of Non‐Hodgkin lymphoma in Denmark: A Population‐based Case–Control Study
No full textThere is limited evidence regarding a possible association between exposure to ambient air pollutants and the risk of non‐Hodgkin lymphoma (NHL). Previous epidemiological studies have relied on crude estimations for air pollution exposure and/or small numbers of NHL cases. The objective of our study was to analyze this association based on air pollution modeled at the address level and NHL cases identified from the nationwide Danish Cancer Registry. We identified 20,874 incident NHL cases diagnosed between 1989 and 2014 and randomly selected 41,749 controls matched on age and gender among the entire Danish population. We used conditional logistic regression to estimate odds ratios (ORs) and adjusted for individual and neighborhood level sociodemographic variables. There was no association between exposure to PM2.5, BC, O3, SO2 or NO2 and overall risk of NHL but several air pollutants were associated with higher risk of follicular lymphoma, but statistically insignificant, for example, PM2.5 (OR = 1.15 per 5 μg/m3; 95% CI: 0.98–1.34) and lower risk for diffuse large B‐cell lymphoma (OR = 0.92 per 5 μg/m3; 95% CI: 0.82–1.03). In this population‐based study, we did not observe any convincing evidence of a higher overall risk for NHL with higher exposure to ambient air pollutants
Evaluation of tire derived rubber (TDR) fixed biofilm reactor (FBR) for remediation of Methylene blue dye from wastewater
No full textThe present investigation is focused on development of aerobic biofilm on tire derived rubber
(TDR) media and then evaluation of such system for bioremediation of Methylene blue (MB)
dye for 9 weeks. After 9 weeks of operation, the COD, BOD, ammonia and color values have
been declined by 89.2, 98.3, 99.61 and 99.81% respectively, While SEM-EDX results showed
a variance in weight percent of various elements in TDR without biofilm i.e. raw TDR media,
as well as in the 1st and 9th week samples. Moreover, fine and strong peaks were observed in
both the MB simulated wastewater and 9th week TDR samples at 1190, 1300, 1400, 1450, 1500
and 1618 cm-1 respectively by Raman Spectroscopic analysis. Further, FTIR analysis was
performed for the MB simulated wastewater, and absorbance peaks ranging from 1591 to 1363
cm-1 and 3410 cm-1 were observed in all the samples with different intensities. To assess the
biodeterioration of the TDR media, ATR was performed for the raw, 1st, 2nd and 9th week TDR
media samples and in the raw TDR, two important bands, 842 and 2962 cm-1 were noticed
representing –CH=CH and –CH3. A clear variation of bands and peak intensities were observed
in different support media samples. The results indicate that TDR media is a resilient,
chemically resistant material and could be employed for the biofilm growth for biological
treatment of textile dye wastewater
Hybrid Beamforming with Switches and Phase Shifters over Frequency-Selective Channels
No full textThe recent studies on hybrid beamformers with a combination of switches and phase shifters indicate that such methods can reduce the cost and power consumption of massive multiple-input multiple-output (MIMO) systems. However, most of the works have focused on the scenarios with frequency-flat channel models. This letter proposes an effective approach for such systems in frequency-selective channels and presents the closed-form expressions of the beamformer and the corresponding sum-rates. Compared to the traditional subconnected structures, our approach with a significantly smaller number of phase shifters results in a promising performance
HDL-apoA-I kinetics in response to 16 wk of exercise training in men with nonalcoholic fatty liver disease
No full textNonalcoholic fatty liver disease (NAFLD) is characterized by low-circulating concentration of high-density lipoprotein cholesterol (HDL-C) and raised triacylglycerol (TAG). Exercise reduces hepatic fat content, improves insulin resistance and increases clearance of very-low-density lipoprotein-1 (VLDL1). However, the effect of exercise on TAG and HDL-C metabolism is unknown. We randomized male participants to 16 wk of supervised, moderate-intensity aerobic exercise (n = 15), or conventional lifestyle advice (n = 12). Apolipoprotein A-I (apoA-I) and VLDL-TAG and apolipoprotein B (apoB) kinetics were investigated using stable isotopes (1-[13C]-leucine and 1,1,2,3,3-2H5 glycerol) pre- and postintervention. Participants underwent MRI/spectroscopy to assess changes in visceral fat. Results are means ± SD. At baseline, there were no differences between exercise and control groups for age (52.4 ± 7.5 vs. 52.8 ± 10.3 yr), body mass index (BMI: 31.6 ± 3.2 vs. 31.7 ± 3.6 kg/m2), and waist circumference (109.3 ± 7.5 vs. 110.0 ± 13.6 cm). Percentage of liver fat was 23.8 (interquartile range 9.8–32.5%). Exercise reduced body weight (101.3 ± 10.2 to 97.9 ± 12.2 kg; P ˂ 0.001) and hepatic fat content [from 19.6%, interquartile range (IQR) 14.6–36.1% to 8.9% (4.4–17.8%); P = 0.001] and increased the fraction HDL-C concentration (measured following ultracentrifugation) and apoA-I pool size with no change in the control group. However, plasma and VLDL1-TAG concentrations and HDL-apoA-I fractional catabolic rate (FCR) and production rate (PR) did not change significantly with exercise. Both at baseline (all participants) and after exercise there was an inverse correlation between apoA-I pool size and VLDL-TAG and -apoB pool size. The modest effect of exercise on HDL metabolism may be explained by the lack of effect on plasma and VLDL1-TAG
Potential 5G Applications for Connected Vehicles: Use Cases, Opportunities and Challenges
No full textThe fifth generation of wireless networks (5G) is not just an evolutionary upgrade of the previous generations of cellular communications, but rather a revolutionary technology envisioned to meet the access, bandwidth, performance, and latency requirements associated with various vertical industries. In this context, this paper makes an analysis of the capability of 5G systems to support various advanced use cases of the Intelligent Transport Systems (ITS) industry. First, the most representative ITS use cases and associated scenarios are selected and described together with their key challenges. To efficiently trial the considered use case scenarios, a three-step method is proposed, where the focus will be initially on performing local tests and eventually evolve towards interconnected multi-site setups. Finally, the technical opportunities and business challenges associated with the future application of 5G to intelligent road transport are discussed and some of the future directions are highlighted
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