Inelastic behavior of structural components

A more accurate procedure was developed for the determination of the inelastic behavior of structural components. The actual stress-strain curve for the mathematical of the structure was utilized to generate the force-deformation relationships for the structural elements, rather than using simplified models such as elastic-plastic, bilinear and trilinear approximations. relationships were generated for beam elements with various types of cross sections. In the generational of these curves, stress or load reversals, kinematic hardening and hysteretic behavior were taken into account. Intersections between loading and unloading branches were determined through an iterative process. Using the inelastic properties obtained, the plastic static response of some simple structural systems composed of beam elements was computed. Results were compared with known solutions, indicating a considerable improvement over response predictions obtained by means of simplified approximations used in previous investigations

A WiFi-based Reliable Network Architecture for Rural Regions

WiFi is being considered as an attractive option in providing low cost Internet connectivity to rural areas, and thereby reducing Digital Divide with urban areas. Most of the WiFi-based Long Distance network architectures extend Internet to rural regions through a single gateway node which is connected to high speed Internet. If the gateway node fails in such single gateway-based rural networks, the entire network gets collapsed. In this paper, we propose a reliable and low-cost WiFi based rural network architecture using multi-gateway concept. The proposed network architecture also allows load balancing among the available gateways. In such multi-gateway architecture, the network recovers from gateway failure and reestablishes the ongoing communication within 2-4 seconds time. The simulation results in NS-2 validate the claims of the paperKeywords—Digital Divide, WiFi, WiFi based Long Distance Network

Tuberculosis diagnosis and treatment practices of private physicians in Karachi, Pakistan

In a densely populated urban area of Karachi, Pakistan, a questionnaire survey was made of the knowledge and practices of 120 private general practitioners about the diagnosis and treatment of tuberculosis (TB). The majority knew that cough, fever and weight loss were the main symptoms of TB, but less than half knew that blood in sputum, poor appetite and chest pain were associated with the disease. Only 58.3% of physicians used sputum microscopy for diagnosing TB and 35.0% used it as a follow-up test. Only 41.7% treated TB patients themselves, the remaining referring their patients to specialists. Around 73.3% of the doctors were aware of the 4 first-line anti-TB drugs. Efforts to improve the knowledge of private practitioners, and strategies to enhance public-private collaboration forTB control in urban areas are urgently required

Mathematical modelling of two-fluid electro-osmotic peristaltic pumping of an Ellis fluid in an axisymmetric tube

This article explores analytically the dynamics of two-fluid electro-osmotic peristaltic flow through a cylindrical tube. The rheology of the fluid in the central core (inner region or core region) is captured through the Ellis equation. The region adjacent to the wall (outer region or peripheral region) is occupied by a Newtonian fluid. The equations governing the flow in each region are modeled by using the appropriate suppositions of long wavelength and low Reynolds number. Closed form expressions for stream function corresponding to each region are obtained and utilized to determine the axial pressure gradient and the interface between the inner and the outer regions. The pumping characteristics, trapping and reflux phenomena are investigated in detail with reference to the Ellis model parameters and the electro-kinetic slip velocity. The present model also generalizes earlier studies from the literature which can be retrieved as special cases. The analysis shows that pressure drop at zero volumetric flow rate is elevated with increasing occlusion parameter. Trapping and reflux phenomena are mitigated with increasing electro-osmotic slip and shear-thinning effects. At larger value of the occlusion parameter an increase in the power-law index reduces the magnitude of the pressure drop. Increasing Ellis rheological parameter reduces the pressure drop over the entire range of occlusion parameters for the case when the peripheral region fluid viscosity exceeds that of the core region fluid. The results obtained may be applicable in the modulation of peristaltic pumping in the efficient operation of various industrial and biomedical devices

Coupling Of The B1g Phonon To The Anti-Nodal Electronic States of Bi2Sr2Ca0.92Y0.08Cu2O(8+delta)

Angle-resolved photoemission spectroscopy (ARPES) on optimally doped Bi2Sr2Ca0.92Y0.08Cu2O(8+delta) uncovers a coupling of the electronic bands to a 40 meV mode in an extended k-space region away from the nodal direction, leading to a new interpretation of the strong renormalization of the electronic structure seen in Bi2212. Phenomenological agreements with neutron and Raman experiments suggest that this mode is the B1g oxygen bond-buckling phonon. A theoretical calculation based on this assignment reproduces the electronic renormalization seen in the data.Comment: 4 Pages, 4 Figures Updated Figures and Tex

Selection of freshwater pearl mussel species for mantle transplantation in Bangladesh

Allograft mantle transplantations were studied in six species of freshwater mussels~ Lamellidens marginalis, L. corrianus~ L. jenkinsianus_, L. phenchooganjensis~ Parreysia corrugata and P. favidens by transplanting foreign mantle tissue into the mantle tissue of a host mussel. After three months of rearing, maximum survivability and pearl formation were observed in L. marginalis and L. jenkinsianus followed by L. corrianus and L. phenchooganjensis. Very poor results were observed in case of Parreysia corrugata and P. favidens. In addition to the natural pearl producing capacity of individual species, survivability and pearl production were related to the size of the mussel species. L. marginalis has been identified as the best species for mantle transplantation in Bangladesh

Fermi Surface reconstruction in the CDW state of CeTe3 observed by photoemission

CeTe3 is a layered compound where an incommensurate Charge Density Wave (CDW) opens a large gap (400 meV) in optimally nested regions of the Fermi Surface (FS), whereas other sections with poorer nesting remain ungapped. Through Angle-Resolved Photoemission, we identify bands backfolded according to the CDW periodicity. They define FS pockets formed by the intersection of the original FS and its CDW replica. Such pockets illustrate very directly the role of nesting in the CDW formation but they could not be detected so far in a CDW system. We address the reasons for the weak intensity of the folded bands, by comparing different foldings coexisting in CeTe3

Air cavity-based vibrational piezoelectric energy harvesters

Introduction. Known vibrational energy harvesting methods use a source of vibration to harvest electric energy. Piezoelectric material works as a sensing element converted mechanical energy (vibration) to electrical energy (electric field). The existing piezoelectric energy harvesting (PEHs) devices have low sensitivity, low energy conversion, and low bandwidth. The novelty of the proposed work consists of the design of PEH’s structure. Air cavity was implemented in the design where it is located under the sensing membrane to improve sensitivity. Another novelty is also consisting in the design structure where the flexural membrane was located at the top of electrodes. The third novelty is a new design structure of printed circuit board (PCB). The purpose of improvised design is to increase the stress in between the edges of PEH and increase energy conversion. With the new structure of PCB, it will work as a substrate that absorbs surrounding vibration energy and transfers it to sensing element. Methods. Three techniques were successfully designed in PEH and fabricated namely PEH A, PEH B, and PEH C were characterized by two experiments: load and vibration. The load experiment measured load pressure towards the PEH, whereas the vibration experiment measured stress towards the PEH. Results. PEH C has the highest induced voltage for a weight of 5.2 kg at the frequency of 50 Hz and the highest stored voltage for a period of 4 min. The three techniques applied in PEHs were showed improvement in transducer sensitivity and energy conversion. Practical value. A piezoelectric acoustic generator was used in the experiment to compare the performance of the designed PEH with available piezoelectric transducers in the market. The new flexible membrane worked as a sensing element was worked as a cantilever beam. PVDF was used as a sensing element due to the flexibility of the polymer material, which is expected to improve sensitivity and operating bandwidth.Вступ. Відомі методи збору вібраційної енергії використовують джерело вібрації для збору електричної енергії. П’єзоелектричний матеріал працює як чутливий елемент, перетворюючи механічну енергію (вібрацію) в електричну енергію (електричне поле). Існуючі пристрої збору п’єзоелектричної енергії (ЗПЕ) мають низьку чутливість, низьке перетворення енергії і малу смугу пропускання. Новизна запропонованої роботи полягає в проектуванні конструкції ЗПЕ. У конструкції реалізована повітряна порожнина, яка розташована під чутливої мембраною для підвищення чутливості. Ще один елемент новизни полягає в конструкції, в якій вигиниста мембрана розташована у верхній частині електродів. Третя новизна - це нова конструкція друкованої плати. Мета запропонованої конструкції - збільшити механічну напругу між краями ЗПЕ і підвищити перетворення енергії. Завдяки новій конструкції друкованої плати вона буде працювати як підкладка, яка поглинає навколишню енергію вібрації і передає її на чутливий елемент. Методи. Три методи були успішно використані для проектування ЗПЕ,  і відповідно названі виготовлені ЗПЕ A, ЗПЕ Б і ЗПЕ В були описані двома експериментальними характеристиками: навантаження і вібрація. В експерименті з навантаженням вимірювався тиск навантаження на ЗПЕ, в той час як в експерименті з вібрацією вимірювалася механічна напруга на ЗПЕ. Результати. ЗПЕ В має найвищу індуковану напругу для ваги 5,2 кг при частоті 50 Гц і найвищу збережену напругу протягом 4 хвилин. Три методи, що застосовуються для ЗПЕ, показали поліпшення чутливості перетворювача і перетворення енергії. Практична цінність. В експерименті використовувався п’єзоелектричний акустичний генератор для порівняння характеристик розробленого ЗПЕ з доступними на ринку п’єзоелектричними перетворювачами. Нова гнучка мембрана працювала як чутливий елемент, що представляв собою консольну балка. В якості чутливого елемента використовувався полівініліден фторид завдяки гнучкості полімерного матеріалу, який, як очікується, поліпшить чутливість і робочу смугу пропускання