A Comparative Study of the Effects of Substrate Composite Materials on External and Internal Handset Antenna EM Absorption

Cellular phones are used in the vicinity of a human head, which absorbs power from antenna radiation. This investigation analyzes the effects of antenna substrate materials on electromagnetic (EM) absorption in a human head. Antennas are used in analysis with four different dielectric substrate materials, which are Bakelite, FR4 glass epoxy, Rogers R04003, and Taconic TLC. Moreover, two different thicknesses of each substrate are considered in the experimental setup. The EM absorption associated with two types of cell phone antennas is evaluated in the closed vicinity of the human head model. One of them is planar inverted-F antenna (PIFA), which is used as the internal handset antenna and another one is helical antenna, which is used as external handset antenna. This investigation consists of two different operating frequency bands, GSM 900 MHz and DCS 1800 MHz. The EM absorption in the human head is presented using the peak specific absorption rate (SAR) and total absorbed power (TAP) by the user. The finite-difference time-domain (FDTD) method based on Computer Simulation Technology (CST) Microwave studio is utilized in this investigation. The obtained results show that the substrate materials do not effect SAR and TAP values considerably for both antennas, but substrate thickness affects the SAR and TAP values significantly. In addition, the substrate thickness affects the SAR and TAP values significantly in most of the cases Moreover, PIFA produces lower SAR than that of a helical antenna significantly for both GSM and DCS frequency band

Composition and microstructure effects on superplasticity in magnesium alloys

Magnesium is the lightest structural metal and magnesium alloys are therefore obvious candidates in weight critical applications. The environmental imperative to reduce vehicle emissions has recently led to intensified research interest in magnesium, since weight reduction is one of the most effective ways of improving fuel efficiency. The hexagonal close-packed structure of magnesium results in poor room temperature formability. However, on heating, several magnesium alloys show superplastic properties, with the ability to deform to very high strains (up to 3000%). This opens up the possibility of forming complex components directly by superplastic forming (SPF). As a result, SPF of magnesium is a highly active research topic. The most widely used class of magnesium alloys contain aluminium as the major alloying addition, which has a relatively high solubility in magnesium, and manganese, which has a less solubility. The effect of these elements on the deformation behaviour and failure mechanisms operating in the superplastic regime is not yet well understood. The objective of this work was to gain fundamental insights into the role of these elements. To do this, alloys with different aluminium content (AZ31 and AZ61) and manganese levels have been studied in-depth.After casting, all alloys were subject to a hot rolling procedure that produced a similar fine grain size and texture in each material. Hot uniaxial testing was performed at temperatures between 300 to 450 degC and at two strain rates to investigate the material flow behaviour, elongation to failure and failure mechanism. All of the alloys exhibited flow curves characterised by an initial hardening and extensive flow softening region. Dynamic recrystallization did not occur, and the flow softening was attributed to grain growth and cavity formation. Increasing the level of aluminium in solution was observed to increase the grain growth rate, and also reduce the strain rate sensitivity. The elongation to failure, however, depended strongly on the manganese level but not on the aluminium content. This attributed to the role of manganese in forming coarse particles that act as sites for cavitation.To study cavity formation and growth, and its effect on failure, a series of tests were conducted to different strain levels followed by investigation of cavitation in 3-dimensions using X-ray tomography. New methods were developed to quantify the correlation between cavities and coarse particles using X-ray tomography data and it was shown that over 90% of cavities are associated with particles. Cavity nucleation occurred continuously during straining, with progressively smaller particles forming cavities as strain increased. The mechanism of cavity formation and growth was identified, and it has been demonstrated that particle agglomerates are effective sites for cavity formation even when the individual particles in the agglomerates are below the critical size predicted by theory for cavity nucleation sites. These results suggest that to improve the ductility of magnesium alloys in the superplasticity regime, it is most critical to minimise the occurrence of particle agglomerates in the microstructure.EThOS - Electronic Theses Online ServiceEPSRCMagnesium ElektronGBUnited Kingdo

Advanced Mutant Line Developed from Fatemadhan Shows Salinity Tolerance at both Seedling and Reproductive Stages

The generation of high-yielding rice mutants and their assessment under salt stress offers a great possibility to isolate salt tolerant line(s) with desired trait of interest. Two separate experiments were conducted at the seedling and reproductive stages of rice to assess the level of salinity tolerance of few advanced high-yielding rice mutants. In the first experiment, rice seedlings were grown under hydroponic conditions and 14-day-old seedlings were subjected to salt stress (EC=10 dS/m; 7 days). Salt stress caused significant reduction in root and shoot length and biomass and leaf chlorophyll content; however, a little reduction was found in the mutant Line-1. In contrast, a sharp increase in shoot Na+/K+ ratio was found in all the genotypes except, Binadhan-10, FL-478 and the mutant Line-1, which exhibited little increased ratio. The second experiment involved exposure of plant to salt stress (EC=10 dS/m) for three weeks at the late booting stage in a sizable plastic tub filled with field soil. Salt stress resulted in a significant decrease in yield and yield attributing traits in all the genotypes except Binadhan-10. Grain yield per panicle was found significantly positive correlation with panicle length, the number of filled grains per panicle, and 100-seed weight under both control and salt stress conditions. Based on the studied traits and stress tolerance indices, Binadhan-10 and mutant Line-1 categorized as salt tolerant and rest of the genotypes were categorized as susceptible, which is also evident from the biplot of principal component analysis. Considering the results from both of the experiments, mutant Line-1 was found tolerant genotype at both seedling and reproductive stage. However, further studies are required to determine the genetic issues controlling the salinity tolerance in mutant Line-1 and the high-yield potential of mutant Line-65 under control condition in a way to develop salt tolerant and high-yielding rice varieties, respectively

Plasma treatment in textile industry

Plasma technology applied to textiles is a dry, environmentally- and worker-friendly method to achieve surface alteration without modifying the bulk properties of different materials. In particular, atmospheric non-thermal plasmas are suited because most textile materials are heat sensitive polymers and applicable in a continuous processes. In the last years plasma technology has become a very active, high growth research field, assuming a great importance among all available material surface modifications in textile industry. The main objective of this review is to provide a critical update on the current state of art relating plasma technologies applied to textile industryFernando Oliveira (SFRH/BD/65254/2009) acknowledges Fundacao para a Cioncia e Tecnologia, Portugal, for its doctoral grant financial support. Andrea Zille (C2011-UMINHO-2C2T-01) acknowledges funding from Programa Compromisso para a Cioncia 2008, Portugal

Prognostic model to predict postoperative acute kidney injury in patients undergoing major gastrointestinal surgery based on a national prospective observational cohort study.

Background: Acute illness, existing co-morbidities and surgical stress response can all contribute to postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery. The aim of this study was prospectively to develop a pragmatic prognostic model to stratify patients according to risk of developing AKI after major gastrointestinal surgery. Methods: This prospective multicentre cohort study included consecutive adults undergoing elective or emergency gastrointestinal resection, liver resection or stoma reversal in 2-week blocks over a continuous 3-month period. The primary outcome was the rate of AKI within 7 days of surgery. Bootstrap stability was used to select clinically plausible risk factors into the model. Internal model validation was carried out by bootstrap validation. Results: A total of 4544 patients were included across 173 centres in the UK and Ireland. The overall rate of AKI was 14·2 per cent (646 of 4544) and the 30-day mortality rate was 1·8 per cent (84 of 4544). Stage 1 AKI was significantly associated with 30-day mortality (unadjusted odds ratio 7·61, 95 per cent c.i. 4·49 to 12·90; P < 0·001), with increasing odds of death with each AKI stage. Six variables were selected for inclusion in the prognostic model: age, sex, ASA grade, preoperative estimated glomerular filtration rate, planned open surgery and preoperative use of either an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker. Internal validation demonstrated good model discrimination (c-statistic 0·65). Discussion: Following major gastrointestinal surgery, AKI occurred in one in seven patients. This preoperative prognostic model identified patients at high risk of postoperative AKI. Validation in an independent data set is required to ensure generalizability

Salinity tolerance and transcriptomics in rice

Morpho-physiological characterization and whole genome transcript profiling of rice genotypes that belongs to sub-species Indica, Japonica and wild relatives were carried out under salt stress. The existence of qualitatively different mechanisms of salt tolerance across the genotypes was identified. Multivariate analysis was applied to categorize the genotypes according to their level of tolerance. Modified SAM analysis elucidated the trait specific expression of genome wide transcripts. Gene ontology enrichment analysis identified the genes involved in different molecular functions such as signal transduction, transcription factor and ion homeostasis etc. Gene network analysis identified the regulatory network of genes that are active in different tissues. The differential expression of transcripts of four tolerant and two susceptible Indica genotypes under stress were further analysed. The candidate genes for different biological processes and molecular functions are identified and discussed. Highly induced stimulus responsive gene Os01g0159600 (OsLEA1a) and Os05g0382200 (Nhx) can be mentioned for instance. The differentially expressed genes that are located within the salt stress related QTLs were also identified. The transcriptomics data were also used to predict the salinity tolerance of genotypes using OSC-PLSDA model. The combined physiological and transcriptomic approach of this study gives a complementary whole organism assessment of plants responses to salt stress

Trait Specific Expression Profiling of Salt Stress Responsive Genes in Diverse Rice Genotypes as Determined by Modified Significance Analysis of Microarrays

Stress responsive gene expression is commonly profiled in a comparative manner involving different stress conditions or genotypes with contrasting reputation of tolerance/resistance. In contrast, this research exploited a wide natural variation in terms of taxonomy, origin and salt sensitivity in eight genotypes of rice to identify the trait specific patterns of gene expression under salt stress. Genome wide transcptomic responses were interrogated by the weighted continuous morpho-physiological trait responses using modified Significance Analysis of Microarrays. More number of genes was found to be differentially expressed under salt stressed compared to that of under unstressed conditions. Higher numbers of genes were observed to be differentially expressed for the traits shoot Na+/K+, shoot Na+, root K+, biomass and shoot Cl-, respectively. The results identified around sixty genes to be involved in Na+, K+ and anion homeostasis, transport and transmembrane activity under stressed conditions. Gene Ontology (GO) enrichment analysis identified 1.36% (578 genes) of the entire transcriptome to be involved in the major molecular functions such as signal transduction (>150 genes), transcription factor (81 genes) and translation factor activity (62 genes) etc. under salt stress. Chromosomal mapping of the genes suggests that majority of the genes are located on chromosomes 1, 2, 3, 6 & 7. The gene network analysis showed that the transcription factors and translation initiation factors formed the major gene networks and are mostly active in nucleus, cytoplasm and mitochondria whereas the membrane and vesicle bound proteins formed a secondary network active in plasma membrane and vacuoles. The novel genes and the genes with unknown functions thus identified provide picture of a synergistic salinity response representing the potentially fundamental mechanisms that are active in the wide natural genetic background of rice and will be of greater use once their roles are functionally verified

Resolving geo-spatial semantic conflicts – an interoperability issue

Purpose – Many organizations in the local community environment use and produce geo-spatial data, so the need for integration of geo-data is increasing rapidly. Different user groups have different views of the world and information is available in a heterogeneous format. This paper seeks to discuss the need for interoperability in local communities taking Chittagong city of Bangladesh as an example. Design/methodology/approach – These communities use geo-spatial data in their own format. This results in semantic conflicts, arising when there is a need for integration of the geo-spatial data. Consequently, the interaction among the aforesaid organizations in terms of data is difficult to achieve and therefore, it is difficult to share the benefit of the recently evolving Information Technology. Taking the above viewpoint into account, this paper presents a framework to address such semantic data conflicts, considered as an issue of interoperability, using ontology. Findings – This paper presented an ontology-based architecture which can be used in resolving semantic conflicts, enabling the tackling of the interoperability issue, faced by the various local communities. The proposed architecture will reduce the computational time significantly because it does not require processing each query every time Research limitations/implications – The architecture presented needs to test with real data in the near future. Practical implications – In order to share the geo-data available in different formats, there is a need for developing a global community, consisting of an integrator, global schema and common ontology. Originality/value – It has been shown that the architecture allows the sharing of geo-data by resolving geo-semantic conflicts of the local communities. This will in turn play an important role in addressing the interoperability problem, faced by these communities.Geophysics, Interface management, Semantics, Space technology

Effective medium ratio obeying multiple octagonal split-ring resonators based metamaterial for tri-band applications

A new tri-band metamaterial unit-cell structure designed and simulated that has multiple octagonal metal rings one inside the other in this paper. The each ring of metamaterial structure delivers a resonance at various frequencies. The number of metal ring resonator has created numbers of resonances. In this paper, different analysis has been performed to verify distinct resonance frequencies, effective medium ratio and effective medium parameters simply by changing the design parameters. Finite-difference time-domain (FDTD) method based Computer Simulation Technology (CST) electromagnetic simulator, which is commercially available is utilized to investigate the design of the metamaterial. The tri-band response has been exhibited of the metamaterial in conjunction with left handed material property over the certain period in the microwave regime. The reported structure has become suitable for S-band (weather radar, radio astronomy, mobile phones, wireless LAN, and GPS), C-band (long distance radio communications), and X-band (satellite communication and space communication) applications and has attained efficient electrically small microwave structure

Double elliptical resonator based quadruple band metamaterial absorber for EMI shielding applications in microwave regime

A quadruple band wide angle polarization insensitivity metamaterial absorber based on double elliptical resonator structure for electromagnetic interference (EMI) shielding applications in microwave regime has been considered in this paper. The proposed metamaterial absorber (MA) unit cell comprises of a top metallic resonating patch and a ground copper, both of which are separated by an inexpensive FR-4 substrate with a thickness of 0.0185λ and an electrical size of 0.138λ, at lowest resonance frequency. The proposed MA demonstrates the peak absorption of 97 %, 99.9 %, 99.9 % and 99.6 % at 3.46 GHz, 6.44 GHz, 7.89 GHz and 12.44 GHz, respectively for transverse-electric (TE) mode at normal incidence. The quadruple band absorption mechanism has been understood by the analysis of electromagnetic field with surface current distribution. In addition, the designed MA also exhibits near unity absorption for a polarization and oblique incident angle up to 60° for TE mode. The proposed MA offers greater than 35 dB shielding effectiveness in all bands under both simulated and measured environment. The designed MA has been fabricated and measured to validate the simulation results. The agreement between the measured and simulated results allow for EMI shielding applications in microwave regime