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A CONFERENCE between manufacturers and representatives of the Aeronautics Branch of the U.S. Department of Commerce was held on September 14 to discuss certain proposed changes in the airworthiness requirements of Aeronautics Bulletin No. 7‐A (the current issue of which is dated January 1933) which were put forward by the Department.

The non-stationary operational wind loads vary in time and site and has remarkable effect on wind turbine drive train. The purpose of this paper is to determine the effects of wind class 3 and 7 on the life of wind turbine drive train. The two-wind class 3 and 7 are described by average wind speed and weight factor and effects of two variables on wind energy generation and wind turbine drive train studied.

The load distribution method is used to calculate stress range cycles for wind class 3 and 7. To determine the rise of force on wind turbine drive train, the load cycle method is proposed. The fatigue damage model is studied with respect to influence of different wind speeds and wind shear factor and then results analysed accordingly. Also sensitivity analysis has been carried out to assess the percentage of drop of energy generation and rise of tangential force for wind class 3 and 7. Linear fit method is used to determine the inclination of wind variation and wind shear of wind class 3 and 7. In this regard, two practical wind sites fall under the wind class 3 and 7 and 1.5 MW wind turbine have been taken in to account.

The results showed that the average rise of force on wind turbine drive train is 37.5% which can influence the drop in energy 34.7% for wind class 3. Similarly, the results of wind class 7 are showing that the average rise in force and drop in energy found to be 49.05% and 51.16%, respectively. The wind class 7 have higher tendency of wind fluctuations and weight factor that can cause a damage to wind turbine drive train components. The results showed that when wind speed increases to rated power 11.5 m/s the damages occurred and remain steady. Similarly, when weight factor increased from 0.18 to onwards the damage occurred. The increased wind loads increased the tangential loads on the wind turbine decreased life of the gearbox.

The results of study suggest that wind turbine should be design according to site specific wind environment for maximum energy generation and lowers the wind loads on the drive train component.

This paper gives a review of the finite element techniques (FE) applied in the analysis and design of machine elements; bolts and screws, belts and chains, springs and dampers, brakes, gears, bearings, gaskets and seals are handled. The range of applications of finite elements on these subjects is extremely wide and cannot be presented in a single paper; therefore the aim of this paper is to give FE researchers/users only an encyclopaedic view of the different possibilities that exist today in the various fields mentioned above. An Appendix included at the end of the paper presents a bibliography on finite element applications in the analysis/design of machine elements for 1977‐1997.

A method is presented for calculating influence coefficients in multispar wings of any plan form. Shear deflexion, chordwise bending and taper are taken into account. All the bending material is concentrated at the rib and spar booms and the skin is assumed to carry only shear. The method is particularly useful in the early stages of design as it is rapid and gives a good internal load distribution. The choice of the method, the assumptions made, and the idealization of the structure are discussed. The structure is reduced to a system of beams and torque boxes, the latter connected to the beams by vertical shear at their corner nodes. The internal forces are first expressed as functions of the displacements at the nodes by means of stiffness coefficients. Next the equations of equilibrium, at each node, are established. Finally the conditions of compatibility are brought in. The solution of this system of equations gives the matrix of influence coefficients. Wherever vertical loads only are applied it is possible to solve for the moment equations of straight beams separately from the remainder of the structure, hence from the stiffness matrix. For convenience, these straight beams are organized into sub‐matrices whose moment equations are ‘reduced’. The specific end conditions also allow further reductions. The internal loads can be obtained by substituting the influence coefficients back into the sub‐matrices and by considering the equilibrium of the beams. The angular displacements of the nodes may also be calculated in a similar manner by using the ‘reduced’ rows from the sub‐matrices.

The purpose of this paper is to analyze annual energy expenditure in the presence of non-linear load and substation voltage harmonics in distribution systems. Economic assessment of non-sinusoidal energy is a challenging task that involves complex computations of harmonic load powers and harmonic line losses.

The paper evaluates fundamental and non-sinusoidal components of electrical energy by applying backward/forward sweep technique in distorted distribution systems. This work involves harmonic power computations at the substation by including harmonic losses occurring in various lines of the distribution system.

The paper found that annual energy expenditure significantly depends upon the non-linear load, supply voltage harmonics and type of tariff structure considered in the distribution system. Impact of individual harmonic orders on the energy billing is also assessed.

The paper concludes that considering harmonic distortions in the distribution system analysis would help electricity regulators formulate adequate pricing structures, which would further generate appropriate economic signals for electricity utility and the consumers.

This paper aims to develop a pose/force coordination method for a redundant dual-arm robot to achieve a symmetric coordination task.

A novel control strategy of dual-arm coordination is proposed that associates pose coordination with force coordination. The spatial in-parallel spring and damping model is built to regulate the relative pose error of two end-effectors in real time, and force coordination factor is introduced to realize the dynamic distribution of loadings to limit the object’s internal force in real time.

The proposed method was verified on a real dual-arm robot platform. The symmetric coordination task is performed and the experiment results show that a good behavior on the regulation of the relative pose errors between two arms to achieve the object’s trajectory tracking, and the distribution of the two end-effectors’ loadings to limit the object’s internal force.

The benefits of the proposed method are to improve the object’s tracking performance and avoid the object damage during the symmetric coordination task.

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Council, Reports and Technical Memoranda of the United States National Advisory Com‐mittee for Aeronautics and publications of other similar Research Bodies as issued

I AM delighted to dedicate my hundredth publication to a young and forward‐looking institution with clearly defined long‐term objectives and well considered determination to live up to the requirements of modern aeronautics and space technology— to the Department of Aeronautics and Space Technology (DEPAST) of the Northampton College of Advanced Technology. Unavoidably, I am looking at the DEPAST‐NCL, through the critical eyes of experience gained in the U.S.S.R., U.S.A., Germany, France, Holland and, of course, in Great Britain; and yet I feel I can say coram populo—coram publico that here we have something British, yet as dynamic and vigorous as any Continental or American educational/ research establishment known to me.

Peter Morrison, Minister of State for Employment, addressing the Engineering Employer's Federation in London, said: