Investigation of electrical properties for cantilever-based piezoelectric energy harvester

In the present era, the renewable sources of energy, e.g., piezoelectric materials are in great demand. They play a vital role in the field of micro-electromechanical systems, e.g., sensors and actuators. The cantilever-based piezoelectric energy harvesters are very popular because of their high performance and utilization. In this research-work, an energy harvester model based on a cantilever beam with bimorph PZT-5A, having a substrate layer of structural steel, was presented. The proposed energy scavenging system, designed in COMSOL Multiphysics, was applied to analyze the electrical output as a function of excitation frequencies, load resistances and accelerations. Analytical modeling was employed to measure the output voltage and power under pre-defined conditions of acceleration and load resistance. Experimentation was also performed to determine the relationship between independent and output parameters. Energy harvester is capable of producing the maximum power of 1.16 mW at a resonant frequency of 71 Hz under 1g acceleration, having load resistance of 12 k Omega. It was observed that acceleration and output power are directly proportional to each other. Moreover, the investigation conveys that the experimental results are in good agreement with the numerical results. The maximum error obtained between the experimental and numerical investigation was found to equal 4.3%

Magnetoacoustics of the Low-Dimensional Quantum Antiferromagnet Cs2CuCl4 with Spin Frustration

We report on results of sound-velocity and sound-attenuation measurements in the triangular-lattice spin-1/2 antiferromagnet Cs₂CuCl₄ (T_N = 0.6 K), in external magnetic fields up to 14 T, applied along the <em>b</em> axis, and at temperatures down to 300 mK. The results are analyzed with a quasi-two-dimensional hard-core boson theory based on exchange-striction coupling. There is a good qualitative agreement between theoretical and experimental results.Citation: Sytcheva, A. et al. (2010). 'Magnetoacoustics of the low-dimensional quantum antiferromagnet Cs₂CuCl₄', Journal of Low Temperature Physics, 159(1-2), 109-113. [Available at http://www.springer.com/materials/journal/10909]. © The Authors 2010. This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any non-commercial use, distribution, and reproduction in any medium, provided the original authors and source are credited.

Appraisal of ethnobotanical uses of the wetland plants of Punjab, Pakistan

Background: Aquatic and semiaquatic plants have a multiplicity of traditional and ethnopharmacological uses ranging from medicinal, famine food to fodder and others. Therefore, the present study was carried out during the years 2008-2011 to document the locally used medicinal, ethnobotanical and traditional data of aquatic and semiaquatic plants of the Punjab, Pakistan.Material and Method: Various visits of the study area were made to collect the data of these plants included local name, habit and habitat with special emphasis on their therapeutic uses against different human ailments. The local elderly, knowledgable people and herbal healers were also interviewed during the visits.Results: A total of thirty-four aquatic and semiaquatic plants were collected and out of these, eighteen plants belonging to the three monocotyledonous and fourteen dicotyledonous families were reported to medicinal and food value as well as found useful in making ropes, mats, baskets and soil binding.Conclusion: The wetland of Punjab (Pakistan) possesses a variety of medicinal plants that are being utilized against various human diseases, e.g.Respiratorial, dermatological, gastrontological, neurological and cardio-vascular diseases.Key Words: Ethnobotanical uses, wetland plants, and herbal medicines

Perangkat Lunak Berbasis Web Sebagai Modul Evaluator Mata Kuliah Perancangan Basis Data

Bentuk kreativitas dalam proses pembelajaran, salah satunya dengan memanfaatkan teknologi informasi untukkegiatan UAS, menggunakan perangkat lunak modul evaluator. Sesuai esnsinya UAS sebagai salah satu bentukevaluasi memiliki beberapa fungsi diantarnya fungsi selektif, diagnostik, penempatan dan pengukurankeberhasilan. Tetapi juga proses ujian, yang dihadiri dosen pengampu, sebagai proses pembelajaran,setidaknya merupakan pelaksanaan pengajaran, secara implisit menyertakan model pengajaran facilitator dandelegator. Apresiasi dan eksplorasi hasil ujian dapat dilakukan sesaat setelah kegiatan tes diselenggarakandiharapkan dapat menjadi kesimpulan akhir pembelajaran. Keseluruhan proses ujian selain dapat dimanfaatkanuntuk melaksanakan pembelajaran, juga menanamkan nilai-nilai prestasi, kompetensi, kejujuran, independensi,kepribadian,komitmen, transparansi dan pemanfaatan IT dalam proses evaluasi

Antécédents culturaux et identification de quelques pratiques paysannes en replantation cacaoyère en Côte d'Ivoire

La Côte d’Ivoire est le premier producteur mondial de cacao, avec plus de 1700 000 tonnes. Cette performance a été atteinte, principalement, par l’accroissement des superficies cultivées aux dépends de la forêt. L’enquête a concerné les parcelles de cacaoyers de moins de 5 ans (0-5 ans) et chaque producteur a été enquêté individuellement, chacun sur sa parcelle, afin de confronter les réponses aux observations de terrain. Les résultats des enquêtes effectuées, entre 2002 et 2003, par le projet PIC-CACAO, montrent que trois types d’antécédents culturaux sont actuellement utilisés pour la culture du cacaoyer en Côte d’Ivoire. Il s’agit des vieilles cacaoyères, des vieilles caféières et des jachères, moins favorables à la culture du cacaoyer. Face aux contraintes rencontrées au cours du renouvellement du verger cacaoyer sur ces antécédents, les producteurs ont, soit adopté des techniques proposées par la recherche, soit adapté certaines de leurs pratiques endogènes aux nouvelles conditions écologiques et naturelles du milieu. Les adoptions ont concernés l’utilisation de matériel végétal amélioré, issu des pépinières, sur les jachères. Quant aux adaptations, elles se sont traduites par la pratique de fortes densités de plantation de jeunes cacaoyers et par la densification de l’ombrage.Mots clés: Cacaoyer, antécédents culturaux, adoptions, adaptations, Côte d’IvoireEnglish Title: Cropping history and identification of some farmer pratices in cocoa replanting in Côte d’IvoireEnglish AbstractCôte d’Ivoire is the first producer of cocoa worldwide with more than 1700 000 tons. This performance was reached, mainly, by the increase of acreages at the expense of the forest. The investigation concerned the cocoa plots under 5 years (0-5 years) and each producer was investigated individually, each on his plot in order to compare his responses with field observations. The results of the investigations carried out, between 2002 and 2003, by PIC-cacao project, show that three types of antecedents are currently used for the culture of the cocoa-tree. They are the old cocoa plantations, the old coffee plantations and the fallow, less favourable of the cultivation of cocoa. Faced with the constraints during the renewal of the cocoaorchard on these antecedents, producers adopted techniques proposed by research or adapted some endogenous practices to the new ecological and natural conditions of the environment. The adoptions related to the use of vegetable material improved and nurseries on the fallow. As for the adaptations, they resulted in the use of high densities of plantation of young cocoa-trees and to the thickening of the shade.Keywords: Cocoa-orchard (Theobroma cacao L.), farming antecedents, adoptions, adaptations, Côte d’Ivoir

An Integer Programming Approach to the Student-Project Allocation Problem with Preferences over Projects

The Student-Project Allocation problem with preferences over Projects (SPA-P) involves sets of students, projects and lecturers, where the students and lecturers each have preferences over the projects. In this context, we typically seek a stable matching of students to projects (and lecturers). However, these stable matchings can have different sizes, and the problem of finding a maximum stable matching (MAX-SPA-P) is NP-hard. There are two known approximation algorithms for MAX-SPA-P, with performance guarantees of 2 and 32 . In this paper, we describe an Integer Programming (IP) model to enable MAX-SPA-P to be solved optimally. Following this, we present results arising from an empirical analysis that investigates how the solution produced by the approximation algorithms compares to the optimal solution obtained from the IP model, with respect to the size of the stable matchings constructed, on instances that are both randomly-generated and derived from real datasets. Our main finding is that the 32 -approximation algorithm finds stable matchings that are very close to having maximum cardinality

Radio variability of 1st 3-months Fermi blazars at 5 GHz: affected by interstellar scintillation?

Blazars from the first-three-months Fermi-AGN list were observed with the Urumqi 25m radio telescope at 5GHz in IDV (Intra-Day Variability) mode and inter-month observation mode. A significant correlation between the flux density at 5GHz and the gamma-ray intensity for the Fermi-LAT detected blazars is seen. There is a higher IDV detection rate in Fermi detected blazars than those reported for other samples. Stronger variability appears at lower Galactic latitudes; IDV appears to be stronger in weaker sources, indicating that the variability is affected by interstellar scintillation.Comment: 4 pages, 4 figures, in proceedings of 'Multiwavelength Variability of Blazars' in Guangzhou Uni. of China, 22-24, Sep. 2010, to appear in JA