7,223 research outputs found
Evaluation of electric and magnetic fields distribution and SAR induced in 3D models of water containers by radiofrequency radiation using FDTD and FEM simulation techniques
In this study, two software packages using different numerical techniques
FEKO 6.3 with Finite-Element Method (FEM) and XFDTD 7 with Finite Difference
Time Domain Method (FDTD) were used to assess exposure of 3D models of square,
rectangular, and pyramidal shaped water containers to electromagnetic waves at
300, 900, and 2400 MHz frequencies. Using the FEM simulation technique, the
peak electric field of 25, 4.5, and 2 V/m at 300 MHz and 15.75, 1.5, and 1.75
V/m at 900 MHz were observed in pyramidal, rectangular, and square shaped 3D
container models, respectively. The FDTD simulation method confirmed a peak
electric field of 12.782, 10.907, and 10.625 V/m at 2400 MHz in the pyramidal,
square, and rectangular shaped 3D models, respectively. The study demonstrated
an exceptionally high level of electric field in the water in the two identical
pyramid shaped 3D models analyzed using the two different simulation
techniques. Both FEM and FDTD simulation techniques indicated variations in the
distribution of electric, magnetic fields, and specific absorption rate of
water stored inside the 3D container models. The study successfully
demonstrated that shape and dimensions of 3D models significantly influence the
electric and magnetic fields inside packaged materials; thus, specific
absorption rates in the stored water vary according to the shape and dimensions
of the packaging materials.Comment: 22 pages, 30 figures and 2 table
The Relationship Between Equity Dependence and Environmental Performance
How does a corporationâs dependence on its shareholders affect the sustainability of its commitment to environmental performance? Although the literature has investigated how the financial markets respond to environmental and green initiatives, it has yet to examine the relationship between a firmâs commitment to the environment and its dependence on the equity markets. In this research, we explore the relationship between equity dependence and environmental performance and find equity dependence is significantly related to corporationsâ environmental concerns but not their environmental strengths
Anti-inflammatory and antioxidant properties of Eriobotrya japonica leaves extracts
Background: In the present work we determined phenolic and flavonoids content of Eriobotrya japonica leaves extracts and fractions and their antioxidant and anti-inflammatory properties.Objectives: To evaluate the inhibition of inflammatory PLA2 and antioxidant effects of extracts and fractions from Eriobotrya japonica leavesMethods: Antioxidant activity was evaluated with DPPH radical scavenging assay and anti-inflammatory effect of fractions was measured by their inhibition potency on the human pro-inflammatory phospholipase A2 (group IIA).Results: The EtOH/EtOAc 2:1 extract exhibited a potent inhibition of the hG-IIA with an IC50 values of 8 Οg/ml. It also shows an antioxidant activity measured on DPPH with an IC50 of 42 Οg/ml. Fractionation shows that CH2Cl2/MeOH 0:1 fraction was the rich one on flavonoids compounds (4.3 mg/g dry weight) and demonstrates a high antioxidant activity with an IC50 of 12 Οg/ml. The anti-inflammatory evaluation demonstrates that the same fraction was the best one to inhibit the pro-inflammatory phospholipase A2 group IIA with an IC50 of 4 Οg/ml.Conclusion: Study conducted on Eriobotrya japonica shows that CH2Cl2/MeOH 0:1 fraction inhibits efficiently the hGIIA phospholipase.which is considered as pro-inflammatory enzyme.Keywords: Eriobotrya japonica, extraction, flavonoids, anti-inflammatory
LeadershipââŹâ˘s Thinking Process with Contextual Intelligence in Executing Diversification Strategy
Abstract: Diversification is a popular strategy for growth in response to a volatile economy. Current research, however, devotes little attention to the leadership required to ensure successful diversification, except for theoretical contributions on leadersââŹâ˘ thinking processes from scholars within the strategy discipline. This study thus conducted fieldwork in South African organisations to explore empirically how senior leadersââŹâ˘ thinking processes, demonstrating contextual intelligence, contributing to successful diversification. A qualitative study was conducted by collecting data through semi-structured interviews from 15 executives with an average of 21 yearsââŹâ˘ experience in senior management roles, who had been involved in diversification in South Africa. A critical incident interview technique was used, and interviewees offered examples of how they changed their way of thinking in creating an environment for successful diversification. The analysis revealed that continuous change was required to successfully implement a diversification strategy. Leaders demonstrated specific thinking processes, for example: being intently aware of their context, they filtered and compared this information to their schema or preconceived cognitive representations. In case of a mismatch, they changed their way of thinking; and directed contextual information to challenge othersââŹâ˘ current way of thinking. Surprising findings included leadersââŹâ˘ sensing otherââŹâ˘s emotions and appealing to these through storytelling to elicit support for their diversification. Diversification requires organisations to invest in developing the agility and global perspective of leadership to increase awareness of trends in their context, their own biases and to shift their mindsets as well as purposefully challenging otherââŹâ˘s thinking
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The sensitivity of the ENSO to volcanic aerosol spatial distribution in the MPI large ensemble. In open review for ESD
Using the Max Planck Institute Grand Ensemble (MPI-GE) with 200 members for the historical simulation (1850â2005), we investigate the impact of the spatial distribution of volcanic aerosols on the ENSO response. In particular, we select 3 eruptions (El ChichĂłn, Agung and Pinatubo) in which the aerosol is respectively confined to the Northern Hemisphere, the Southern Hemisphere or equally distributed across the equator. Our results show that the ENSO anomalies start at the end of the year of the eruption and peak the following one. Especially, we found that when the aerosol is located in the Northern Hemisphere or is symmetrically distributed, El NiĂąo-like anomalies develop while aerosol distribution confined to the Southern Hemisphere leads to a La NiĂąa-like anomaly. Our results strongly point to the volcanically induced displacement of the ITCZ as the main mechanism that drives the ENSO response, while suggesting that the other mechanisms (the ocean dynamical thermostat, the cooling of tropical northern Africa or of the Maritime continent) commonly invoked to explain the post-eruption ENSO response appear not to be at play in our mode
MAT-758: CONSTRUCTABILITY BENEFITS OF THE USE OF LIGHTWEIGHT FOAMED CONCRETE FILL (LFCF) IN PAVEMENT APPLICATIONS
Lightweight Foamed Concrete Fill (LFCF), also known as cellular concrete, has been growing in use in transportation infrastructure projects over recent years. LFCF is a versatile construction material that has now been in use for over 30 years. A number of recent road rehabilitation projects have demonstrated some of the benefits of use. With a greater emphasis on sustainability on all provincial and municipal road projects, new solutions are being sought to minimize the generation of waste and deliver better performing pavements that require less maintenance interventions. Roads over peat and organic deposits pose challenges for road agencies. They are subject to continual and long term settlements that necessitate frequent patch repairs. The downside of such repairs is that the additional weight of the new asphalt, triggers further settlement. Traditionally, permanent solutions have necessitated the total reconstruction of the road section and removal of the underlying organic layers. This is expensive, creates huge traffic disruptions, generates waste and consumes large volumes of aggregate for the reinstatement. The use of lightweight fill offers an alternative as it allows the pavement to be âfloatedâ above the organic layer. However, the traditional lightweight materials, such as polystyrene, have been prohibitively expensive for such applications. In recent years, LFCF has been successfully used as a cost effective solution in road works. LFCF is a foamed, pumpable, cementitious fill with a density of only 475 kg/m3, about a quarter of that of conventional granular fill. With a compressive strength of at least 0.5 MPa, it has sufficient strength to support pavement loads. However, the real advantages relate to constructability, since the material can be installed very quickly, minimizes excavation time, can be placed in winter and does not require conventional compaction or associated testing. This paper will provide an overview of the use of LFCF for road works, including typical specifications, quality control/assurance requirements, and performance based on a number of case study applications
A Firefly-inspired method for protein structure prediction in lattice models
We introduce a Firefly-inspired algorithmic approach for protein structure prediction over two different lattice models in three-dimensional space. In particular, we consider three-dimensional cubic and three-dimensional face-centred-cubic (FCC) lattices. The underlying energy models are the Hydrophobic-Polar (H-P) model, the MiyazawaâJernigan (M-J) model and a related matrix model. The implementation of our approach is tested on ten H-P benchmark problems of a length of 48 and ten M-J benchmark problems of a length ranging from 48 until 61. The key complexity parameter we investigate is the total number of objective function valuations required to achieve the optimum energy values for the H-P model or competitive results in comparison to published values for the M-J model. For H-P instances and cubic lattices, where data for comparison are available, we obtain an average speed-up over eight instances of 2.1, leaving out two extreme values (otherwise, 8.8). For six M-J instances, data for comparison are available for cubic lattices and runs with a population size of 100, where, a priori, the minimum free energy is a termination criterion. The average speed-up over four instances is 1.2 (leaving out two extreme values, otherwise 1.1), which is achieved for a population size of only eight instances. The present study is a test case with initial results for ad hoc parameter settings, with the aim of justifying future research on larger instances within lattice model settings, eventually leading to the ultimate goal of implementations for off-lattice models
Price-and-verify: a new algorithm for recursive circle packing using DantzigâWolfe decomposition
This is the author accepted manuscript. The final version is available from Springer via the DOI in this recordâŻPacking rings into a minimum number of rectangles is an optimization problem which appears naturally in the logistics operations of the tube industry. It encompasses two major difficulties, namely the positioning of rings in rectangles and the recursive packing of rings into other rings. This problem is known as the Recursive Circle Packing Problem (RCPP). We present the first dedicated method for solving RCPP that provides strong dual bounds based on an exact DantzigâWolfe reformulation of a nonconvex mixed-integer nonlinear programming formulation. The key idea of this reformulation is to break symmetry on each recursion level by enumerating one-level packings, i.e., packings of circles into other circles, and by dynamically generating packings of circles into rectangles. We use column generation techniques to design a âprice-and-verifyâ algorithm that solves this reformulation to global optimality. Extensive computational experiments on a large test set show that our method not only computes tight dual bounds, but often produces primal solutions better than those computed by heuristics from the literature.Federal Ministry of Education and Researc
Efficient Removal of Ultrafine Particles from Diesel Exhaust by Selected Tree Species : Implications for Roadside Planting for Improving the Quality of Urban Air
Human exposure to airborne ultrafine (?1 Îźm) particulate pollution may pose substantial hazards to human health, particularly in urban roadside environments where very large numbers of people are frequently exposed to vehicle-derived ultrafine particles (UFPs). For mitigation purposes, it is timely and important to quantify the deposition of traffic-derived UFPs onto leaves of selected plant species, with particularly efficient particle capture (high deposition velocity), which can be installed curbside, proximal to the emitting vehicular sources. Here, we quantify the size-resolved capture efficiency of UFPs from diesel vehicle exhaust by nine temperate-zone plant species, in wind tunnel experiments. The results show that silver birch (79% UFP removal), yew (71%), and elder (70.5%) have very high capabilities for capture of airborne UFPs. Metal concentrations and metal enrichment ratios in leaf leachates were also highest for the postexposure silver birch leaves; scanning electron microscopy showed that UFPs were concentrated along the hairs of these leaves. For all but two species, magnetic measurements demonstrated substantial increases in the concentration of magnetic particles deposited on the leaves after exposure to the exhaust particulates. Together, these new data show that leaf-deposition of UFPs is chiefly responsible for the substantial reductions in particle numbers measured downwind of the vegetation. It is critical to recognize that the deposition velocity of airborne particulate matter (PM) to leaves is species-specific and often substantially higher (?10 to 50 times higher) than the "standard" V d values (e.g., 0.1-0.64 cm s -1 for PM 2.5) used in most modeling studies. The use of such low V d values in models results in a major under-estimation of PM removal by roadside vegetation and thus misrepresents the efficacy of selected vegetation species in the substantial (âŤ20%) removal of PM. Given the potential hazard to health posed by UFPs and the removal efficiencies shown here (and by previous roadside measurements), roadside planting (maintained at or below head height) of selected species at PM "hotspots" can contribute substantially and quickly to improve in urban air quality and reductions in human exposure. These findings can contribute to the development and implementation of mitigation policies of traffic-derived PM on an international scale
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