On the strength of columns

The main object of these experiments was to determine how columns behave before collapse under axial loading. The original title of the research was "An investigation into the factors determining the strength of built-up steel struts". The title had to be amended as the testing machines necessitated the use of "model" sections.In mathematical investigations the columns considered are taken as ideal, and therefore materially different from actual columns. To some extent this difference could be attributed to the difference between theoretical assumed conditions of elasticity and those found in actual metals as manufactured. A more important cause of the difference is the varying nature of the end conditions employed. The results of the accurate researches of such men as Tetmajer, Hodgkinson, Christie and Howard, who brought with them not only ripe experience but careful and clear methods of experimenting are a testimony to the difficulty of reconciling theory and experiment.In the enthusiasm generated more than 150 years ago by the work of Euler, mathematical formulae were established with the purpose of making allowance for the imperfections existing in a practical column. So far a 3 the author is aware the subject has been treated only mathematically and no one has approached it experimentally, except to determine the effects of the direct eccentricity of loading. Despite the many minute mathematical investigations made, the comparative accuracy and even the validity of them is still doubtful. The a uthor’s discussions on the "Imperfection tests" show that the only variant of noteworthy consequence is the eccentricity of loading: the other imperfections, unless of a critical magnitude, having practically negligible effects on the ultimate strength of a column.Among the most notable features of the au t h o r ’s work could be considered the collective view of the stress-strain diagrams, thejintroduction of the virtual coefficients of elasticity, the definite divisions of the column graph, quantitative data about "permanent set", "imperfection tests" and the method for the adequate allowance in area due to rivet holes in a built-up piece.The bending formulae determined for long columns represent more accurately most of the experimental results. The yield range,- represented by a straight line law,- has not been definitely formulated. This is due to the fact that the exact values of the critical compressive and the tensile stress determining the range were not known with sufficient accuracy for the materials used by the earlier experimenters. No one, except Robertson, has carried out crushing tests with a view to determine the exact compressive stress-strain relations. It can be stated that the yield range will be represented by an equation of the formp = A + B - Cx2/k , where A - a constant depending on the material. B = a constant depending on the end conditions, C =a reducing factor depending on the end conditions.The behaviour of built-up columns has been the subject of world-wide discussion. The author’s views regarding the "non-homogeneous" action of the columns and the reduction in area for rivet holes are fully described in this Thesis.Though the present investigations embrace only a’”limited part of the vast field of experimental columns, the author feels that similar methods applied to full-sized sections will give results of value to the practical designer. A programme of column tests should include not only tension tests but also crushing tests with a view to determine the primary stress-strain relations. More "rivetreduction" experiments are needed to test the conclusions arrived at for the adequate allowance in area due to rivet holes

Numerical Modeling of a Wave Turbine and Estimation of Shaft Work

Wave rotors are periodic-flow devices that provide dynamic pressure exchange and efficient energy transfer through internal pressure waves generated due to fast opening and closing of ports. Wave turbines are wave rotors with curved channels that can produce shaft work through change of angular momentum from inlet to exit. In the present work, conservation equations with averaging in the transverse directions are derived for wave turbines, and quasi-one-dimensional model for axial-channel non-steady flow is extended to account for blade curvature effects. The importance of inlet incidence is explained and the duct angle is optimized to minimize incidence loss for a particular boundary condition. Two different techniques are presented for estimating the work transfer between the gas and rotor due to flow turning, based on conservation of angular momentum and of energy. The use of two different methods to estimate the shaft work provides confidence in reporting of work output and confirms internal consistency of the model while it awaits experimental data for validation. The extended wave turbine model is used to simulate the flow in a three-port wave rotor. The work output is calculated for blades with varying curvature, including the straight axial channel as a reference case. The dimensional shaft work is reported for the idealized situation where all loss-generating mechanisms except flow incidence are absent, thus excluding leakage, heat transfer, friction, port opening time, and windage losses. The model developed in the current work can be used to determine the optimal wave turbine designs for experimental investment

Dynamical Behaviour of Excimers

738-73

Foreseeing India-China relations : the 'compromised context' of rapprochement

For more about the East-West Center, see http://www.eastwestcenter.org/</a

Automatic semantic segmentation and classification of remote sensing data for agriculture

Automatic semantic segmentation has expected increasing interest for researchers in recent years on multispectral remote sensing (RS) system. The agriculture supports 58 % of the population, in which 51 % of geographical area is under cultivation. Furthermore, the RS in agriculture can be used for identification, area estimation and monitoring, crop detection, soil mapping, crop yield modelling and production modelling etc. The RS images are high resolution images which can be used for agricultural and land cover classifications. Due to its high dimensional feature space, the conventional feature extraction techniques represent a progress of issues when handling huge size information e.g., computational cost, processing capacity and storage load. In order to overcome the existing drawback, we propose an automatic semantic segmentation without losing the significant data. In this paper, we use SOMs for segmentation purpose. Moreover, we proposed the particle swarm optimization technique (PSO) algorithm for finding cluster boundaries directly from the SOMs. On the other hand, we propose the deep residual network to achieve faster training process. Deep Residual Networks have been proved to be a very successful model on RS image classification. The main aim of this work is to achieve the overall accuracy greater than 85 % (OA > 85 %). So, we use a convolutional neural network (CNN), which outperforms better classification of certain crop types and yielding the target accuracies more than 85 % for all major crops. Furthermore, the proposed methods achieve good segmentation and classification accuracy than existing methods. The simulation results are further presented to show the performance of the proposed method applied to synthetic and real-world datasets

Volumetric Plasma Discharge in a Coaxial Electrode Configuration Using Repetitively Pulsed Nanosecond Discharges

Transient plasma discharges can be created in di erent electrode geometries and the use of a coaxial electrodes can assist in initiating ignition at multiple points at the same time to create volumetric ignition. The current study investigates discharge formation in a coaxial electrode in quiescent, atmoshpheric and non-reacting conditions. This is the rst systematic study to understand the behavior of such a discharge as a function of di erent pulse parameters like pulse width (40-110 ns), repetition frequency (1-50 kHz) and input voltage (14-20 kV). Additionally, the polarity of the central electrode was changed between positive and negative. An intensi ed ccd camera was used to visualize the discharge for- mation. The exposure of the camera is set to capture 500 discharges in a single frame. The discharges were found to behave di erently for positive and negative polarity discharges. The positive polarity discharge tends to form a strong arc and spins around the outer cylinder which is con rmed using a high speed camera. The negative polarity discharges form a uniform streamer discharge for most of the pulse parameters. The current study has provided an initial understanding of the dynamics of plasma discharges in a coaxial electrode

A REVIEW ON PHARMACO KINETIC DRUG INTERACTIONS OF STATINS

The 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) are generally well tolerated as monotherapy. Statins are associated with two important adverse effects, asymptomatic elevation in liver enzymes and myopathy. Myopathy is most likely to occur when statins are administered with other drugs. Statins are substrates of multiple drug transporters (including OAT- -P1B1, BCRP and MDR1) and several cytochrome P450 (CYP) enzymes (including CYP3A4, CYP2C8, CYP2C19, and CYP2C9). Possible adverse effects of statins can occur due to interactions in concomitant use of drugs that substantially inhibit or induce their methabolic pathway. This review aim is to summarize the most important interactions of statins