Electromagnetic modeling of large and non-uniform planar array structures using Scale-Changing Technique (SCT)

Les structures planaires de grandes tailles sont de plus en plus utilisées dans les applications des satellites et des radars. Deux grands types de ces structures à savoir les FSS et les Reflectarrays sont particulièrement les plus intéressants dans les domaines de la conception RF. Mais en raison de leur grande taille et de la complexité des cellules élémentaires, l‘analyse complète de ces structures nécessite énormément de mémoire et des temps de calcul excessif. Par conséquent, les techniques classiques basées sur maillage linéaire soit ne parviennent pas à simuler de telles structures soit, exiger des ressources non disponibles à un concepteur d'antenne. Une technique appelée « technique par changement d'échelle » tente de résoudre ce problème par partitionnement de la géométrie du réseau par de nombreux domaines imbriqués définis à différents niveaux d'échelle du réseau. Le multi-pôle par changement d'échelle, appelé « Scale changing Network (SCN) », modélise le couplage électromagnétique entre deux échelles successives, en résolvant une formulation intégral des équations de Maxwell par une technique basée sur la méthode des moments. La cascade de ces multi-pôles par changement d'échelle, permet le calcul de la matrice d'impédance de surface de la structure complète qui peut à son tour être utilisées pour calculer la diffraction en champ lointain. Comme le calcul des multi-pôles par changement d'échelle est mutuellement indépendant, les temps d'exécution peuvent être réduits de manière significative en parallélisant le calcul. Par ailleurs, la modification de la géométrie de la structure à une échelle donnée nécessite seulement le calcul de deux multi-pôles par changement d'échelle et ne requiert pas la simulation de toute la structure. Cette caractéristique fait de la SCT un outil de conception et d'optimisation très puissant. Des structures planaires uniformes et non uniformes excité par un cornet ont étés modélisés avec succès, avec des temps de calcul délais intéressants, employant les ressources normales de l'ordinateur. ABSTRACT : Large sized planar structures are increasingly being employed in satellite and radar applications. Two major kinds of such structures i.e. FSS and Reflectarrays are particularly the hottest domains of RF design. But due to their large electrical size and complex cellular patterns, full-wave analysis of these structures require enormous amount of memory and processing requirements. Therefore conventional techniques based on linear meshing either fail to simulate such structures or require resources not available to a common antenna designer. An indigenous technique called Scale-changing Technique addresses this problem by partitioning the cellular array geometry in numerous nested domains defined at different scale-levels in the array plane. Multi-modal networks, called Scale-changing Networks (SCN), are then computed to model the electromagnetic interaction between any two successive partitions by Method of Moments based integral equation technique. The cascade of these networks allows the computation of the equivalent surface impedance matrix of the complete array which in turn can be utilized to compute far-field scattering patterns. Since the computation of scale-changing networks is mutually independent, execution times can be reduced significantly by using multiple processing units. Moreover any single change in the cellular geometry would require the recalculation of only two SCNs and not the entire structure. This feature makes the SCT a very powerful design and optimization tool. Full-wave analysis of both uniform and nonuniform planar structures has successfully been performed under horn antenna excitation in reasonable amount of time employing normal PC resources

Optimal Level of Participatory Approach in an NGO Development Project

Many authors, Bradley (2006), Banerjee (2007), Mohan (2008) and Sen (1999) among others, argue that the participatory approach in the development projects of a non-governmental organization, NGO, is more effective and sustainable than the externally imposed expert-driven approach. According to this research stream, the participatory approach promotes self-respect, dignity, inclusiveness, and empowerment of people involved in the project and, simultaneously, it improves the external local environment for the NGO. The key point of this paper is that adopting only the participatory approach may not be optimal, as this approach involves costs to learn about local culture, values and attitudes, and to design and implement feasible participatory development practices. Accordingly, an economically sensible and sustainable strategy for the NGO will be to use a mixture of both approaches. In this paper, the optimal level of participatory approach is theoretically derived and numerically illustrated

Quantization of Length in Spaces with Position-Dependent Noncommutativity

We present a novel approach to quantizing the length in noncommutative spaces with positional-dependent noncommutativity. The method involves constructing ladder operators that change the length not only along a plane but also along the third direction due to a noncommutative parameter that is a combination of canonical/Weyl-Moyal type and Lie algebraic type. The primary quantization of length in canonical-type noncommutative space takes place only on a plane, while in the present case, it happens in all three directions. We establish an operator algebra that allows for the raising or lowering of eigenvalues of the operator corresponding to the square of the length. We also attempt to determine how the obtained ladder operators act on different states and work out the eigenvalues of the square of the length operator in terms of eigenvalues corresponding to the ladder operators. We conclude by discussing the results obtained.Comment: 14 pages, 1 figur

Natural Interpretation of UML/MARTE Diagrams for System Requirements Specification

International audienceTo verify embedded systems early in the design stages, we need formal ways to requirements specification which can be as close as possible to natural language interpretation, away from the lower ESL/RTL levels. This paper proposes to contribute to the FSL (Formal Specification Level) by specifying natural language requirements graphically in the form of temporal patterns. Standard modeling artifacts like UML and MARTE are used to provide formal semantics of these graphical models allowing to eliminate ambiguity in specifications and automatic design verification at different abstraction levels using these patterns

Patterns of Antibiotic Drug Resistance among Salmonella Typhi Isolates of Enteric Fever in Pediatric Population at a Tertiary Care Hospital

Objective: To determine patterns of antibiotic drug resistance among Salmonella typhi isolates of enteric fever in pediatric population at a tertiary care hospital. Material and methods: Consecutive 161 children with enteric fever were included in this study. This cross – sectional study was done at Department of Pediatric Medicine, Nishtar Medical University and Hospital, Multan from June 2015 to December 2016. Venous blood sample (3-5 ml) was drawn and it was immediately transported to Microbiology laboratory of Pathology Department, Nishtar Hospital Multan for blood culture and sensitivity test. Antibiotic drug resistance was determined after measuring diameter of zone of inhibition of a specific drug on Salmonella isolates on Mueller Hinton agar plates by modified Kirby baur disc diffusion method. Coated tongue, pain abdomen, anorexia and headache was assessed clinically. All the data were entered and analyzed using SPSS-11. Results: Of these 161 study cases, 91 (56.5%) were boys and 70 (43.5%) were girls. Mean age of our study cases was 5.79 ± 2.45 years (with minim age was 2 years while 12 years was maximum age). Previous history of use of antibiotics before 48 hours of the culture and sensitivity test was present in 93 (57.8%) of our study cases. Majority of our study cases having enteric fever presented with abdominal pain 65 (40.4%), headache 28 (17.4%) and diarrhea 17.4 % of our study cases. Chloramphenicol was sensitive in 40 (24.8%) of the Salmonella typhi isolates, Ampicillin was sensitive in 20 (12.4%), Co-trimoxazole in 20 (12.4%), Ciprofloxacin was sensitive in 88 (54.7%) isolates, Ofloxacin was sensitive in 101 (62.7%), Gentamycin was sensitive in 28 (17.4 %), Amoxycillin was sensitive in 36 (22.4 %). Conclusion: Our study results have indicated that S. typhi isolates of enteric fever showed higher degree of antibiotic drug resistance. Multidrug resistant strains were more prevalent in our study which points towards well directed efforts of our health policy makers to adopt certain guidelines regarding use of these drugs in our population. Keywords: Enteric fever, drug resistance, children

Burden of congenital heart diseases in a tertiary cardiac care institute of high altitude area

Background: Congenital heart disease is one of the major causes of mortality and morbidity in the paediatric population of both the developing and developed countries. Variability in incidence and prevalence of CHD from various countries of Indian subcontinent and rest of the world could be because of genetic, cultural, and environmental factors.  The objective of the study was to find the prevalence and pattern of CHD in a tertiary care hospital in Kashmir (Jammu and Kashmir).Methods: All children admitted at territary care hospital with age 0-15 years were screened for congenital heart disease. The study was conducted for period of one year to ascertain the prevalence and spectrum of CHDs.Results: A total of 232 patients out of 23000, were found having CHDs measuring a prevalence of 10.5/1000. About 170 (73%) were the acyanotics, and 62 (27%) were cyanotic heart patients. Among the acyanotic heart diseases ventricular septal defect was the most frequent lesion seen in 54 (23%), followed by patent ductus arteriosus in 50 (22%) children. Among the cyanotic heart diseases tetralogy of Fallot was the most frequent cyanotic heart disease seen in 15 (6.4%) patients.Conclusions: Authors observed high prevalence of CHD in our population. The pattern and spectrum of CHD were comparable to national and international data

Spiral Computed Tomographic Evaluation and Endodontic Management of a Mandibular Second Molar with Four Roots. A Case Report and Literature Review

The vast majority of mandibular second molars have two roots with three root canals; however, variations in molar root canal anatomy are not uncommon. To the best of our knowledge, four rooted mandibular second molar with three mesial roots and one distal root has never been reported. Herein, we present the endodontic management of a four rooted mandibular second molar tooth, diagnosed with the assistance of spiral computed tomography (SCT) with a brief review of literature

PAKISTAN’S TRADE POLICIES, NON-TARIFF MEASURES AND CONCERNS OF STAKEHOLDERS

Pakistan can increase its exports by 12 billion dollars till 2024 if integration with international market is improved, and strong linkages are developed among value chains (ITC, 2020). But this potential development is facing impediments due to transparency issues, imposition of non-tariff measures, ambiguous regulations at home and lack of information among both importers and exporters. This paper is dedicated to the discussion of Pakistan’s trade policies, tariff structure, rules governing non-tariff measures, and discussion about the concerns of business community and other stakeholders on NTMs. Application of NTMs in Pakistan, and their shortcomings are also discussed in detail. Then based on these discussions some recommendations are forwarded. Study shows that most of the hurdles faced by traders are home borne. If regulations are made easier at home and mutual recognition of standards is acquired with partner countries, then across the border trade can become much easier

A Framework to Specify System Requirements using Natural interpretation of UML/MARTE diagrams

International audienceThe ever-increasing design complexity of embedded systems is constantly pressing the demand for more abstract design levels and possible methods for automatic verification and synthesis. Transforming a text-based user requirements document into semantically sound models is always difficult and error-prone as mostly these requirements are vague and improperly documented. This paper presents a framework to specify textual requirements graphically in standard modeling formalisms like uml and marte in the form of temporal and logical patterns. The underlying formal semantics of these graphical models allow to eliminate ambiguity in specifications and automatic design verification at different abstraction levels using these patterns. The semantics of these operators/patterns are presented formally as state automatons and a comparison is made to the existing ccsl relational operators. To reap the benefits of mde, a software plugin TemLoPAC is presented as part of the framework to transform the graphical patterns into ccsl and Verilog-based observers

UML/MARTE pour la spécicationd'exigences systèmes (version étendue)

To verify embedded systems early in the design stages, we need formal ways to requirements specification which can be as close as possible to natural language interpretation, away from the lower ESL/RTL levels. This paper proposes to contribute to the FSL (Formal Specification Level) by specifying natural language requirements graphically in the form of temporal patterns. Standard modeling artifacts like UML and MARTE are used to provide formal semantics of these graphical models allowing to eliminate ambiguity in specifications and automatic design verification at different abstraction levels using these patterns.Pour vérifier des systèmes embarqués tôt dans le cycle de conception, il est nécessaire de disposerde langages d'exigences aussi proche que possible de l'expression des besoins en langage naturel. Ce papier s'inscrit dans l'initiative FSL (Formal Specification Level) et propose un langage graphique, s'appuyant sur UML pour décrire des exigences formelles basées sur un ensemble de patrons temporels. Il réutilise très largement des constructions UML et MARTE et s'appuie sur la sémantique du langage CCSL pour éliminer les ambiguïtés dans les spécifications, exécuterles modèles et permettre la vérification de ces modèles au niveau système