Rotating Arm-Based Experimental Study on Droplet Behavior in the Shoulder Region of an Aircraft Aerodynamic Surface

An experimental study has been performed on water droplet deformation in the shoulder region of an airfoil. The experiments have been carried out in a rotating arm facility 2.2 m long and able to rotate up to 400 rpm (90 m/s). A blunt airfoil model (chord length equal to 0.468 m) was placed at the end of the arm. A droplet generator was used to generate a stream of water droplets with an initial diameter of 1000 μm. An imaging system was set up to record the trajectories and deformations of the droplets in three different regions close to the airfoil shoulder. The base flow field was characterized using a particle image velocimetry system. The experiments show that droplet deformation results in the shoulder region of the airfoil are different from those pertaining to the leading edge region. In particular, droplets in the shoulder region tend to rotate to the direction of the incoming airfoil which generates an interference effect between the droplets that make up the stream. These differences have been quantified applying an existing theoretical model specifically developed for the leading edge region to the results obtained in the present study

Design of QSD Multiplier Using VHDL

The need for high speed digital circuits became more prominent as portable multimedia and communication applications incorporating information processing and computing. The drawback of modern computers lead to the worsening in performance of arithmetic operations such as addition, subtraction, multiplication on the aspects of carry propagation time delay, high power consumption and large circuit complexity.Binary Signed Digit Numbers are known to allow limited carry propagation with more complex addition process. Some of the limitations of this system are computational speed which limits formation and propagation of carry especially as the number of bits increases. Therefore it provides large complexity and low storage density. Carry free arithmetic operations can be achieved using a higher radix number system such as Quaternary Signed Digit (QSD) and it allows higher information storage density, less complexity. A high speed area effective adders and multipliers can be implemented using this technique. Carry free addition and other operations on a large number of digits such as 64, 128, or more can be implemented with constant delay and less complexity. The Design is simulated & synthesized using Xilinx 13.1

A new approach in blade shape adjustment in PBD-14 design mode

Thesis (S.M. and Nav.E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2001.Includes bibliographical references (leaves 68-70).The purpose of this study is to develop a more efficient and robust algorithm for adjusting the blade shape as a part of a coupled lifting-surface design/analysis code for marine propulsors developed at MIT, known as PBD-14. The algorithm for adjusting the blade shape in the current version of PBD-14 works satisfactorily in most cases. However, with more complex schemes such as ducted propulsors and/or higher load distributions, the process has to be carefully monitored by the user and the blade surface can develop corrugations in the spanwise direction. A different approach investigated in this study is based on an idea of aligning the blade shape by tracing streamlines. In order to satisfy the kinematic boundary condition, the final blade shape has to exactly match the streamlines of the flow field in which the propeller blade operates. The algorithm that is developed traces streamlines by calculating the total velocity on a grid of points and then exactly fits the blade on this grid of points. Initial tests of this algorithm have demonstrated its robustness by producing accurate blade shapes both in uniform and in more complicated flow fields. Finally, propeller fabrication is investigated, and tolerance issues as well as propeller inspection methods, traditional and modem, are examined. A cost analysis is performed that investigates the economic impact of manufacturing an example propeller according to a certain tolerance system.by Aristomenis Chrisospathis.S.M.and Nav.E

Species composition and population dynamics of phlebotomine sand flies in a Leishmania infected area of Chiang Mai, Thailand

Phlebotomine sand flies are established vectors of leishmaniasis in humans. In Thailand, Leishmania martiniquensis and “Leishmania siamensis” have been described as causative agents of leishmaniasis. In this study, a survey of sand flies in the Leishmania infected area of Hang Dong district, Chiang Mai, Thailand was performed using CDC light traps for eight consecutive months, from January to August 2016. A total of 661 sand flies were collected, and of 280 female sand flies, four species of the genus Sergentomyia including Sergentomyia gemmea, S. barraudi, S. indica, and S. hivernus and one species of the genus Phlebotomus, Phlebotomus stantoni, were identified. S. gemmea and S. hivernus were found in Chiang Mai for the first time. The density of captured female sand flies was high in warm and humid periods from June to August, with temperatures of around 26°C and relative humidity about 74%. In addition, S. gemmea was the most predominant species in the area. Further studies as to whether or not these sand fly species could be a vector of Leishmaniasis in Thailand are required

Didilia sp. Infecting Phlebotomus stantoni in Thailand

Nematode infection in wild caught Phlebotomine sand flies was investigated in Thailand. Light microscopy (LM) and scanning electron microscopy (SEM) were used to detect and morphologically characterize entomopathogenic nematodes that presented in the sand flies. Didilia sp. nematodes were found for the first time in the body cavity of wild caught male Phlebotomus stantoni sand flies. The Didilia sp. was identified based on the morphology of the adult nematodes, from their stylet and teeth at the anterior tip, body length, and egg shell sculpture. It was noted that every infected male sand fly had unrotated genitalia, which would not allow them to mate, thus leading to the loss of their offspring. This finding provided information that might lead to study on whether or not the Didilia sp. has the potential to control sand fly population

Requirements for translation re-initiation in Escherichia coli: roles of initiator tRNA and initiation factors IF2 and IF3

Despite its importance in post-transcriptional regulation of polycistronic operons in Escherichia coli, little is known about the mechanism of translation re-initiation, which occurs when the same ribosome used to translate an upstream open reading frame (ORF) also translates a downstream ORF. To investigate translation re-initiation in Escherichia coli, we constructed a di-cistronic reporter in which a firefly luciferase gene was linked to a chloramphenicol acetyltransferase gene using a segment of the translationally coupled geneV–geneVII intercistronic region from M13 phage. With this reporter and mutant initiator tRNAs, we show that two of the unique properties of E. coli initiator tRNA – formylation of the amino acid attached to the tRNA and binding of the tRNA to the ribosomal P-site – are as important for re-initiation as for de novo initiation. Overexpression of IF2 or increasing the affinity of mutant initiator tRNA for IF2 enhanced re-initiation efficiency, suggesting that IF2 is required for efficient re-initiation. In contrast, overexpression of IF3 led to a marked decrease in re-initiation efficiency, suggesting that a 30S ribosome and not a 70S ribosome is used for translation re-initiation. Strikingly, overexpression of IF3 also blocked E. coli from acting as a host for propagation of M13 phage

Overexpression of DNA Polymerase Zeta Reduces the Mitochondrial Mutability Caused by Pathological Mutations in DNA Polymerase Gamma in Yeast

In yeast, DNA polymerase zeta (Rev3 and Rev7) and Rev1, involved in the error-prone translesion synthesis during replication of nuclear DNA, localize also in mitochondria. We show that overexpression of Rev3 reduced the mtDNA extended mutability caused by a subclass of pathological mutations in Mip1, the yeast mitochondrial DNA polymerase orthologous to human Pol gamma. This beneficial effect was synergistic with the effect achieved by increasing the dNTPs pools. Since overexpression of Rev3 is detrimental for nuclear DNA mutability, we constructed a mutant Rev3 isoform unable to migrate into the nucleus: its overexpression reduced mtDNA mutability without increasing the nuclear one

Electromechanical analysis of an adaptive piezoelectric energy harvester controlled by two segmented electrodes with shunt circuit networks

This paper presents an adaptive power harvester using a shunted piezoelectric control system with segmented electrodes. This technique has spurred new capability for widening the three simultaneous resonance frequency peaks using only a single piezoelectric laminated beam where normally previous works only provide a single peak for the resonance at the first mode. The benefit of the proposed techniques is that it provides effective and robust broadband power generation for application in self-powered wireless sensor devices. The smart structure beam with proof mass offset is considered to have simultaneous combination between vibration-based power harvesting and shunt circuit control-based electrode segments. As a result, the system spurs new development of the two mathematical methods using electromechanical closed-boundary value techniques and Ritz method-based weak-form analytical approach. The two methods have been used for comparison giving accurate results. For different electrode lengths using certain parametric tuning and harvesting circuit systems, the technique enables the prediction of the power harvesting that can be further proved to identify the performance of the system using the effect of varying circuit parameters so as to visualize the frequency and time waveform responses

Systemic importance of financial institutions: regulations, research, open issues, proposals

In the field of risk management, scholars began to bring together the quantitative methodologies with the banking management issues about 30 years ago, with a special focus on market, credit and operational risks. After the systemic effects of banks defaults during the recent financial crisis, and despite a huge amount of literature in the last years concerning the systemic risk, no standard methodologies have been set up to now. Even the new Basel 3 regulation has adopted a heuristic indicator-based approach, quite far from an effective quantitative tool. In this paper, we refer to the different pieces of the puzzle: definition of systemic risk, a set of coherent and useful measures, the computability of these measures, the data set structure. In this challenging field, we aim to build a comprehensive picture of the state of the art, to illustrate the open issues, and to outline some paths for a more successful future research. This work appropriately integrates other useful surveys and it is directed to both academic researchers and practitioners