An electroviscous damper

A new type of vibration damper for rotor systems was developed and tested. The damper contains electroviscous fluid which solidifies and provides Coulomb damping when an electric voltage is imposed across the fluid. The damping capacity is controlled by the voltage. The damper was incorporated in a flexible rotor system and found to be able to damp out high levels of unbalanced excitation. Other proven advantages include controllability, simplicity, and no requirement for oil supply. Still unconfirmed are the capabilities to eliminate critical speeds and to suppress rotor instabilities

Household costs of healthcare during pregnancy, delivery, and the postpartum period : a case study from Matlab, Bangladesh

A household survey was undertaken in Matlab, a rural area of Bangladesh, to estimate the costs incurred during pregnancy, delivery, and the postpartum period for women delivering at home and in a health facility. Those interviewed included 121 women who delivered at home, 120 who delivered in an ICDDR,B basic obstetric care (BEOC) facility, 27 who delivered in a public comprehensive obstetric care (CEOC) hospital, and 58 who delivered in private hospitals. There was no significant difference in total costs incurred by those delivering at home and those delivering in a BEOC facility. Costs for those delivering in CEOC facilities were over nine times greater than for those delivering in BEOC facilities. Costs of care during delivery were predominant. Antenatal and postnatal care added between 7% and 30% to the total cost. Services were more equitable at home and in a BEOC facility compared to services provided at CEOC facilities. The study highlights the regressive nature of the financing of CEOC services and the need for a financing strategy that covers both the costs of referral and BEOC care for those in need.This research was funded under the Cooperative Agreement No. 388-A-00-97-00032-00 with the United States Agency for International Development (USAID) (ICDDR,B Grant No. GR-00089). ICDDR,B acknowledges with gratitude the commitment of USAID to the Centre’s research efforts. Carine Ronsmans and Jo Borghi are funded by the Department for International Development, UK

Simulated rotor test apparatus dynamic characteristics in the 80- by 120-foot wind tunnel

A shake test was conducted in the 80 by 120 foot Wind Tunnel at NASA Ames Research Center, using a load frame and dummy weights to simulate the weight of the NASA Rotor Test Apparatus. The simulated hub was excited with broadband random excitation, and accelerometer responses were measured at various locations. The transfer functions (acceleration per unit excitation force as a function of frequency) for each of the accelerometer responses were computed, and the data were analyzed using modal analysis to estimate the model parameters

Non-isomorphic coding in lattice model and its impact for protein folding prediction using genetic algorithm

Traditional encodings for hydrophobic(H)-hydrophilic(P) model or HP lattice models is isomorphic, which adds unwanted variations for the same solution, thereby slowing convergence. In this paper a novel non-isomorphic encoding scheme is presented for HP lattice model, which constrains the search space. In addition, similarity comparisons are made easier and more consistent and it will be shown that non-deterministic search approach such as genetic algorithm (GA) converges faster when non-isomorphic encoding is employed.Full Tex

Use of exhaust gas recirculation (EGR) and cyclonic separator for simultaneous NOx and PM reduction in DI diesel engines

This study presents the results of exhaust gas recirculation (EGR) and cyclonic separator for simultaneous oxides of nitrogen (NOx) and particulate matter (PM) reduction in a direct injection (DI) diesel engine under different engine loads and speeds. There is a significant NOx reduction by EGR, but PM is hugely increased, especially at high EGR rate-high load conditions. A significant reduction in PM is achieved by the use of cyclonic separator without deteriorating other emissions. At high speed-high load conditions, the cyclonic separator has a greater efficiency. Both NOx and PM reduce simultaneously when EGR and cyclonic separator are used together. Using cyclonic separator with high EGR rates, a remarkable NOx reduction is possible keeping the PM level significantly lower than non-EGR level

Reviewing traffic conflict techniques for potential application to developing countries

The economic and social costs due to road crashes are disproportionately higher in developing countries. In addition, underreporting, coupled with an incomplete and inconsistent recording of reported crashes is a major issue in such settings. A brief outline of the dimension of road safety problems in developing countries and the most common limitations of existing crash databases is given in the paper. The challenges in applying traditional approaches for traffic safety evaluation and initiatives are also discussed. Diagnosis of road safety problems using traffic conflict techniques has received considerable research interest and has gained acceptance as a proactive surrogate measure in developed countries. Significant studies have been accomplished to develop, validate and apply different surrogate indicators for the estimation of traffic conflicts, as well as an assessment of the safety problem in different road geometric and operating conditions. This has provided a substitute for the historical crash records in traffic safety research. The main objective of this paper is to assess the application potentiality of this surrogate safety measures to address safety issues in developing countries. To do that, this paper critically reviews and synthesizes the different indicators of surrogate safety measures. The main principles, as well as advantages and disadvantages of the major indicators and prospects of application, are presented here. Finally, future research directions for road traffic safety assessment are outlined in the perspective of understanding the most concerning human issue due to traffic crashes in developing countries

Impact of Principals' Managerial Roles Under School-based Management on School Improvement at Urban Secondary Schools of Bangladesh

This article aims al observing the relationship between principals' managerial roles and the improvement of schools and the impacts of principals' managerial roles toward school improvement based on the school-based management. This research uses 127 principals and 694 teachers of urban secondary schools of Bangladesh as the sample. Schools are becoming better when the principals give more emphasizing on strategic plan, supportive and comprehensive roles but less emphasizing on shared decision making. The findings of this study offer valuable information for policy makers and educational managers, especially the principals and teachers. Key words: Principals managerial roles, school-based management, teachers' Professional development activities, school improvement &nbsp

Anisotropic nonlinear elasticity in a spherical bead pack: influence of the fabric anisotropy

Stress-strain measurements and ultrasound propagation experiments in glass bead packs have been simultaneously conducted to characterize the stress-induced anisotropy under uniaxial loading. These measurements, realized respectively with finite and incremental deformations of the granular assembly, are analyzed within the framework of the effective medium theory based on the Hertz-Mindlin contact theory. Our work shows that both compressional and shear wave velocities and consequently the incremental elastic moduli agree fairly well with the effective medium model by Johnson et al. [J. Appl. Mech. 65, 380 (1998)], but the anisotropic stress ratio resulting from finite deformation does not at all. As indicated by numerical simulations, the discrepancy may arise from the fact that the model doesn't properly allow the grains to relax from the affine motion approximation. Here we find that the interaction nature at the grain contact could also play a crucial role for the relevant prediction by the model; indeed, such discrepancy can be significantly reduced if the frictional resistance between grains is removed. Another main experimental finding is the influence of the inherent anisotropy of granular packs, realized by different protocols of the sample preparation. Our results reveal that compressional waves are more sensitive to the stress-induced anisotropy, whereas the shear waves are more sensitive to the fabric anisotropy, not being accounted in analytical effective medium models.Comment: 9 pages, 8 figure