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This paper explains a design and the comparison of two multi-disc permanent magnet motor. The actuator must provide answers to the volume constraint and torque. This application is employed in land transport for aeronautical field. The axial flux motors become interesting when obtaining large surfaces of air-gap with the traditional machines is no possible. Indeed, surfaces of air-gap are more important in comparison with a radial flux machine, and, in a given volume, they allow to obtain a higher torque. After having shown the multi-air gap structure, we describe the design method from elementary cells. That's why two types the disc-type motor were selected. This paper clearly shows the efficient topology of a disc-type multi-air gap machine.

This paper presents a novel control strategy for an above-knee powered prosthetic leg that unifies the entire gait cycle, eliminating the need to switch between controllers during different periods of gait. Current control methods divide the gait cycle into several sequential periods each with independent controllers, resulting in many patient-specific control parameters and switching rules that must be tuned by clinicians. Having a single controller could reduce the number of control parameters to be tuned for each patient, thereby reducing the clinical time and effort involved in fitting a powered prosthesis for a lower-limb amputee. Using the Discrete Fourier Transformation, a single virtual constraint is derived that exactly characterizes the desired actuated joint motion over the entire gait cycle. Because the virtual constraint is defined as a periodic function of a monotonically increasing phase variable, no switching or resetting is necessary within or across gait cycles. The output function is zeroed using feedback linearization to produce a single, unified controller. The method is illustrated with simulations of a powered knee-ankle prosthesis in an amputee biped model and with examples of systematically generated output functions for different walking speeds.

Various control strategies are being used to achieve high performance operation of linear motor drives. To maintain minimum volume and weight of the power supply unit on board the transportation vehicle, peak thrust per unit current operation is a desirable objective. True peak thrust per unit current through slip control is difficult to achieve because the parameters of linear induction machines vary during normal operation. This paper first develops a peak thrust per unit current control law based on the per-phase equivalent circuit for linear induction machines. The algorithm for identification of the variable parameters in induction machines is then presented. Application to an operational linear induction machine (LIM) demonstrates the utility of this algorithm. The control strategy is then simulated, based on an operational transit LIM, to show the capability of achieving true peak thrust operation for linear induction machines.

Measurement and analysis experiences have shown great difficulties in interharmonic detection and measurement due to their small amplitudes and their consequent vulnerability from harmonics spectral leakage. The spectral leakage is due to lack of synchronization between the analyzed waveforms actual periods and the sampled window length, deriving from both fundamental frequency deviations and nonsynchronized interharmonics. This paper compares the techniques, that are introduced by the same authors in previous papers and that improve the IEC recommended signal processing: the utilization of the classical Hanning Window, in place of the Rectangular; the harmonic filtering and the self tuning signal processing. All the techniques are applied to numerical and experimental tests showing the different performances.

This paper describes the development of a magnetic sensor system for the evaluation of the condition of prestressed strands inside the bottom layer of concrete box beams. The sensor consists of an electromagnet which magnetizes embedded prestressing strand and measures the magnetic field response of the strands using Hall sensors embedded at different positions on the electromagnet. The novel aspect of this comprehensive system is the integration of measuring magnetic flux leakage (MFL) and main magnetic flux (MMF) signals. A computer-aided simulation model has also been developed to use these signals in estimating corrosion. The MFL signal gives indications of the presence of corrosion and cracks or fractures in the strands. The MMF signal quantifies the amount of steel loss in the strands due to corrosion or rusting. Both these techniques have been independently evaluated using magnetic inspection systems which made them suitable to be used in a single sensor system. This comprehensive system was evaluated in a laboratory setting to identify corrosion and strand breaks in prestressing strands. It was observed that the MFL signal could identify the presence of corrosion and strand breaks, while the MMF signal could be used to estimate the loss of steel due to corrosion. This system was also evaluated using it in an inspection of decommissioned prestressed box beams removed from Ohio’s oldest prestressed box-beam bridge. The findings from this inspection revealed a good match with the dissected areas of the box beams. Steps to move the system to implementation are also discussed. With further development improving the accuracy of this inspection system, it can become a valuable tool to bridge engineers for box-beam inspection.

This paper evaluates the benefits of energy storage systems applied to renewable intermittent sources like wind. With this objective, a 144 MW Portuguese wind farm is used as a case-study. The storage system design and evaluation processes use a computational tool developed in MatLab to simulate the wind farm operation with an energy storage system and computes the remuneration tariff. The energy storage design settles on a system of 5 MW with 30 MWh. The simulation results show a 2.1% gain in wind farm tariff and a improved adjustment on generation to the typical electricity demand curve. Considering the storage system design and an available storage technology survey, one concludes that redox flow batteries are the best suited to application, in spite of their present prices being not the most advantage.

Delivering reliable service requires satisfactory operation of numerous line components, spanning significant geographical areas and subject to environmental, electrical, and mechanical stresses, plus normal aging. Conventional reliability practices use periodic maintenance to minimize failures, coupled with rapid restoration procedures when outages occur. Reliability statistics have shown little change in decades. Newer technologies can shorten outages, by automatically rerouting service to customers on healthy feeder segments, but they: require redundant paths for power flow; react only after outages occur; and often require communications with pole-mounted switches. Over the past decade, Texas A&M University has demonstrated that electrical waveforms, available via conventional substation-based CTs and PTs, contain evidence of failures, incipient failures, and improper operation of feeder equipment, often well before these conditions escalate and cause outages. This provides the basis for conditioned-based maintenance and outage avoidance. This paper provides examples, from operating feeders, demonstrating some of these advances.

After outlining the basic principles of superconductivity and the history of its development, this paper describes some of the potential applications of the technology, particularly for the electricity supply industry. It charts the development of the use of superconductors in energy research from the mid-1960s on, reviewing the projects developed over that period, and considers why the impetus behind such projects dissipated in the 1980s. The events of the last 18 months — since the discovery of high temperature superconducting materials — and the subsequent explosion of interest in the new materials are then examined. Of particular interest here is the contrast between the emergence of a powerful coalition of government, industry and science in a number of countries anxious to obtain maximum advantage from the technology and the reaction of the energy research community. The paper concludes by identifying the problems of the new materials and of superconductivity itself for the ESI, suggesting how they might interact in the future, and considers how these developments illustrate the relationship between the innovation process and technology choice in the energy sector.

In this paper, a new reference waveform estimation strategy based on an adaptive notch filter (ANF) is proposed for unified power quality conditioner (UPQC). Two coupled ANFs are used to generate the reference waveforms for shunt and series components of UPQC. Mathematical properties of proposed algorithm are presented in detail. The technique is simple and its speed and accuracy are controllable. Moreover, robustness against internal parameter variations is a feature of this method. Numerical simulations result show the superiority of the algorithm for compensation of voltage and current distortions in compare with the conventional methods.

Complex operations carried out in the oil and gas industry such as drilling require constant and accurate real-time monitoring of the process. To this aim, a real-time model of the drilling operation is required. Such a model is used to estimate the state of the well when and where direct and reliable measurements are not available and it helps the driller gain an overview of the drilling process. Given the harsh operating environment, sensor reliability and sensor calibration are known problem areas, and bad data quality is a common problem, affecting the accuracy of the model. As a result, the driller may be misled about the downhole situation or receive conflicting claims about operating conditions. A way to reduce uncertainty and increase confidence is to aggregate the opinion of different experts. When the expert is a computer program, such aggregation is often referred to as an ensemble approach. The principle underlies techniques that have become popular in the oil industry in recent years, such as probabilistic forecasting and ensemble Kalman filters. In this paper, we discuss this trend and develop an ensemble system for predicting the bottom-hole pressure during a managed pressure drilling operation. The improved accuracy and robustness of the ensemble approach in situations with bad data quality is demonstrated.

This paper reported synergistic bimetallic AuCu/TiO2 catalysts for selective oxidation of 1,2-propanediol to lactic acid under very mild conditions (T 92%). Surface characterization reveals that while AuCu forms alloy structure with larger particle size based on TEM images, strong interaction between Au and Cu species is critical for performance enhancement. According to experimental studies on the influence of 1,2-propanediol and NaOH concentration on reaction rates, it is highly possible that 1,2-propanediol is reacted following single-site Langmuir–Hinshelwood mechanism while NaOH acts as a promoter and may block surface sites under relatively higher concentration.

The process of selective laser melting (SLM) is complex and instantaneous, which communicates with a variety of physical phenomena such as solid–liquid phase transition. The microstructure and material properties are favorable evidence to explain the SLM forming mechanism. In this paper, the forming properties of the iron-based alloy, titanium-based alloys, and aluminum-based alloys are discussed, which are relatively mature in research. The influence of processing strategy on the density and quality of metal specimens is briefly introduced. The research progress of microstructure and mechanical properties of metal specimens formed by SLM is mainly introduced. Also, the influence of processing parameters and heat treatment on the microstructure and the effect of microstructure on mechanical properties are summarized. The corrosion behavior of metal specimens formed by SLM is analyzed. Furthermore, the research development of copper-based alloys, shape memory alloys, and high-entropy alloys is presented. Finally, the problems encountered in the alloys forming process are described, and the future development direction has prospected.

White LED lamp are gaining a lot of popularity both on the residential and street lighting markets. Those devices are advertised with a very long lifetime compared to conventional incandescent lamps. A measurement campaign including accelerated ageing and stress test is ongoing in Sweden; parts of the data are joined to data obtained in France. The aim of this paper is to report and analyze which factors can be correlated to LED performance changes. A few commercial lamps were bought anonymously in retail stores; each type comprised 12 samples. A first group undergo long-term lumen maintenance test; the second was stressed by frequent switching (50 000 cycles, 30 seconds on/30 second off); the third and the fourth by frequent cycling (3 000 cycles, 30 minutes on/30 minutes off) at 25 °C and 75°C respectively. The assesment are made based on the change of the lumen, lamp efficiency, Correlated Color Temperature and Color Rendering index of the produced light before and after the test.

The calculation of a transformer's parasitics, such as its self capacitance, is fundamental for predicting the frequency behavior of the device, reducing this capacitance value and moreover for more advanced aims of capacitance integration and cancellation. This paper presents a comprehensive procedure for calculating all contributions to the self-capacitance of high-voltage transformers and provides a detailed analysis of the problem, based on a physical approach. The advantages of the analytical formulation of the problem rather than a finite element method analysis are discussed. The approach and formulas presented in this paper can also be used for other wound components rather than just step-up transformers. Finally, analytical and experimental results are presented for three different high-voltage transformer architectures.

Engineering and design professionals constitute a major driving force for a successful project undertaking. Although the industry has been active in addressing the performance of construction labor and methods to estimate or predict such performance, relatively fewer efforts have been conducted for the engineering profession. In an attempt to fill out this gap, the paper presents a study to utilize neurofuzzy intelligent systems for predicting the engineering performance in a construction project. First, neurofuzzy systems are introduced as integrated schemes of artificial neural networks and fuzzy control systems. The use of these neurofuzzy intelligent systems, particularly fuzzy neural networks, in predicting engineering performance is then demonstrated in the industrial construction sector. The development of the system is based on actual project data that was collected through questionnaire surveys. Statistical variable reduction techniques are further employed to develop linear regression models of the same engineering performance prediction scheme, and results are being compared between both techniques.

This paper addressed cable network configurations to improve surface accuracies for large mesh antennas. In this study, we focused on manufacturing error, assembling error, and sensitivity to displacements of support points. To facilitate accuracy management by the lengths of cables, high stiffness cables were used in surface cable network. Then, low stiffness cables were used in other cables. The effect of the lengths of errors was estimated by analysis and experiments for a test model. Micro-gravity test was also executed to estimate the accuracy of shape adjustment on ground. The sensitivity is calculated under some variations of cable stiffness. From the results, it is clarified that the proposed configuration can reduce the surface distortion and keep high surface accuracy.

The detailed switch-level models of front-end diode recti fi er loads can be readily implemented using a number of transient simulation programs, such as PSCAD/EMTDC, and the toolboxes in Matlab/Simulink. To improve the simulation ef fi ciency for the system-level studies, the so-called dynamic ave rage models have been widely used by researchers and en- gineers. Recently, several aver age-value modeling methodologies for the conventional three-phase (six-pulse) front-end recti fi er loads have been discussed, and the dynamic performance of sev- eral developed models has been demonstrated in discontinuous and continuous modes. In this paper, the effects of topological variations of the ac-side fi lters on the system performance are investigated. Also, the steady-st ate and dynamic impedances pre- dicted by the average models under balanced and unbalanced operation are compared. The studies and analyses presented here extend and complement those set forth in the preceding companion publication.

In distribution system, the subject of fault location has been of considerable interest for a long time. The objective of this paper is to develop Cumulative approach for fault location based on statuses of Fault Indicators (FI), Circuit Breakers (CB), Fuses and Fault Impedances from distance protection devices. This approach is using mainly graph theory algorithms and Area Marking Strategy to resolve fault diagnosis problem in electric power networks. Unlike neighborhood approach where one link only affects the marking of neighbor areas, cumulative approach marks all areas down the link. In many situations, cumulative approach may outperform neighbor approach.

Insurance telematics is a disruptive technology that is expected to reform the vehicle insurance industry. Based on sensor data, the traditional measures for calculating the insurance premium are complemented to determine a fee that more accurately predicts the risk profile of the policyholder. From an instrumentation and measurement point of view, there are several insurance telematics challenges that have to be tackled. It is about consistently extracting relevant figures of merit (FoMs) like number of harsh braking, speeding, heavy cornering, trip smoothness, etc, and then to transform these FoMs into a valid measure, or score, that determines the risk profile of the insurance customer. The paper presents a characterization of FoMs in terms of actuarial relevance, the driver's influence, stationarity and observability, which are important for the given task. Dedicated hardware to be fitted into the on-board diagnostics outlet as well as contemporary smartphones are two different insurance telematics platforms for data collection. The paper discusses the properties of the smartphone in the perspective of insurance telematics as a low-cost alternative to the hardwired platforms like the one connected to the vehicle's on-board diagnostics outlet.

In this paper, a thermally actuated medical stent and staple using shape memory alloy (SMA) are designed, numerically analysed, and compared to similarly designed stents and staples made of 316L stainless steel and Co-Cr alloy. The numerical analysis was carried out using finite element method. A consistent 3D model is used to investigate the effect of materials on the performance of the stent and staple. This study takes into account the interaction between the stent/staple and the in vivo environment, by modelling the in vivo environment forces. The results are in good agreement with those reported in the literature. According to the results, it can be concluded that when these three commercially available materials undergo an external force, SMA yields much better results in terms of maximum displacement under the same amount of stress. Especially when undergoing large loads, the SMA produces considerably more displacement than 316L stainless steel and Co-Cr, which suggests that using SMA is a promising path to make biomedical stents and staples.

(1798). XXI. Chemical experiments respecting different methods of rendering paper and the writing on it indestructible by fire. The Philosophical Magazine: Vol. 1, No. 1, pp. 89-92.

(1800). III. On the origin and progress of the manufacture of pig-iron with pit-coal; and comparison of the value and effects of pit-coal, wood, and peat-char. The Philosophical Magazine: Vol. 7, No. 25, pp. 35-46.

The subject of the means of producing artificial cold, or the constitution of frigorific mixtures, I had considered as exhausted, in the Papers I have already had the honour to lay before this Society : so far as relates to that part of the subject which consists in generating artificial cold without the use of ice, it still remains so with me, having nothing new to offer. A considerable acquisition however having been made, since my last Paper “On the best Methods of producing artificial Cold,” by the discovery that a neutral salt, but little known, or attended to, by chemists before, produced extraordinary effects of this kind with ice, it could not fail of attracting my attention.

PurposeThe purpose of this paper is to investigate the Ecodesign Directive and the extent to which it provides a regulatory framework for life‐cycle assessment approaches which underlie integrated product policy (IPP), thus providing a horizontal approach to product legislation as a new approach to regulating pollution.Design/methodology/approachThe paper draws on academic commentary as well as official papers, European communications and legislation.FindingsThe development and application of the Ecodesign Directive is highlighted along with the different regulatory approach it poses which is shown to result from the application of life‐cycle assessment and IPP.Practical implicationsThe impact on the development of products will be extensive in that they will be required by mandatory rules to be designed with a view to the reduction of their whole life environmental impacts.Originality/valueThe approach is to highlight a new paradigm for regulating pollution and environmental impacts.

The facts and results intended to be communicated in this Paper, are founded upon observations made, during the present winter, at the cotton manufactory of Messrs. Philips and Lee at Manchester, where the light obtained by the combustion of the gas from coal is used upon a very large scale; the apparatus for its production and application having been prepared by me at the works of Messrs. Boulton, Watt, and Co. at Soho. The whole of the rooms of this cotton mill, which is, I believe, the most extensive in the United Kingdom, as well as its counting-houses and store-rooms, and the adjacent dwelling-house of Mr. Lee, are lighted with the gas from coal. The total quantity of light used during the hours of burning, has been ascertained, by a comparison of shadows, to be about equal to the light which 2500 mould candles of six in the pound would give; each of the candles, with which the comparison was made consuming at the rate of 4-10ths of an ounce (175 grains ) of tallow per hour.

DSI Underground developed a bolt, based on a frictional, inflatable bolt combined with an internal additional load-bearing element, called the Dynamic Omega-Bolt. This paper provides technical detail of the bolt design and the results of laboratory tests of its performance. Laboratory drop tests conducted at the CanmetMINING laboratories suggest that under dynamic loading, the bolt exhibits a peak tensile strength based on the frictional element combined with a residual loading capacity from the internal element. Failure of both elements of the bolt corresponds to an average absorption of 35 kJ of energy due to steel elongation. The residual loading capacity is in the range of 70 kN and it is intended to retain the dead load of broken rock slabs generated by an event of a sudden release of energy, as long as sufficient friction bond length is retained at both ends of the bolt. The Dynamic Omega-Bolt associates the well-known advantages of inflatable friction bolts such as fast, clean and safe installation, with an improved capacity of energy/deformation absorption from the internal point anchored element.

In the prosecution of my inquiries into the modifications impressed upon light by the various bodies of the animal, the vegetable, and the mineral kingdom, I have had the good fortune to discover several new properties of light, and to establish the laws which regulate the most remarkable of the phenomena. A few of these results have already been laid before the Royal Society ; and from the reception which they have experienced, I have taken the liberty of addressing to you the following paper containing a series of new facts, remark­able for their extreme singularity, and their opposition to almost all our notions of the action of bodies upon the luminous rays. The extraordinary character which these experiments at first assumed, induced me to think that I had overlooked some source of deception ; and it was not till I had performed them under every variety of circumstances, and till they had been repeated, and viewed in the same light by several of my friends, that I prevailed upon myself to bring them under your notice. The splendid exhibition of colours which distinguishes mother of pearl from every other substance, and the succes­sive developement of fresh tints, by every gentle inclination of the plate, have always been ascribed to the lamellated structure of the shell, and have been regarded as a fine proof of Newton's theory of the colours of natural bodies. This explanation I had no disposition to call in question, nor did the general train of my experiments lead me to such an inquiry. In examining the coloured rings which mother of pearl, like the topaz, exhibits by polarised light; and in ascertaining the relation between its refractive power, and the angle at which it gives polarity to the reflected ray, I was under the necessity of grinding and polishing, with the utmost care, various plates of this substance. The developement of new colours, and the extinction of others which took place during these processes, indicated the operation of some unknown and extraordinary cause, and encouraged me to pay the most minute attention to all the phenomena which were presented. The results of this investigation I shall endeavour to explain under the four following heads.

Fig. 1. * This figure is given for the purpose of explaining the mode in which the fibrous disposition of chlorite is effected. The crystallized arrangement which is here so visible is generally observed in those chlorite fibres which occur in transparent quartz. I have never observed it in chalcedony, yet there is little doubt that a similar disposition is equally the cause of the fibrous appearance so common in the specimens which have been figured in the former plates, the chief differences consisting in the smaller size and less perfect crystallization of the chlorite scales. Fig. 2. The crystals of chlorite magnified. Fig. 3. Although in the former plates I figured some specimens which I imagined to be confervæ, I had not then procured any example in which that regularity of structure, which is so conspicuous in some of the plants of this family, could be observed. The present figure exhibits that regularity in a striking manner. Fig. 4. This figure affords a second example of that regular ramification which botanists will immediately recognize as characterizing many of the plants of this tribe; although for the reasons already assigned in the paper, it will be fruitless to attempt to discover the species.

When Mr. Whitby engaged to superintend this most arduous undertaking, Sir Joseph Banks requested him to examine narrowly any caverns he might meet with in the rock, and have the bones, or any other fossil remains that were met with, carefully preserved. Mr. Whitby in compliance with this request, in November 1816, sent up to Sir Joseph Banks a box of fossil bones, which are the subject of the present Paper.

This paper investigates motion planning for under-actuated systems with impacts, as in legged robots. Some such systems admit decoupling vector fields between impacts, and the system can be thought of as a kinematic system as it moves along the integral curves of these decoupling vector fields. This reduces motion planning to choosing a sequence of decoupling vector fields and impact transition times between these vector fields. Each transition must satisfy the condition that the image of the pre-impact state (through the impact mapping) leads to a post-impact state aligned with the new decoupling vector field. We derive this condition, extending previous work where transitions were only allowed at zero velocity. Our approach combines the benefits of computationally efficient kinematic planning with potentially faster execution times due to the fact that the system does not have to be slowed to zero velocity at the switches. Switches are restricted to a lower-dimensional configuration surface, however. We have applied this approach to motion planning for a planar two-link robot which locomotes by using a single revolute actuator at the joint between the links and by alternately clamping one of two possible pivot points to the ground.

It is proposed in this paper to show in what respects the effects of local attraction, in the above mentioned ships, were conformable to the observations which had been made in preceding voyages; and how far the errors, which were found to take place on different courses, and under different dips of the magnetic needle, corresponded with the rules for calculating corrections, which Captain Flinders had found useful in his own experience, and which he had recommended for a more extensive trial. It may be desirable to premise, that the irregularities here alluded to, are not those accidental disturbances which may be caused by iron placed inadvertently too near the compasses ; but the permanent, and constant effect of the mass of iron contained in a ship, affecting its compasses at all times, and in a greater or less degree, according as its influence is more or less powerful, in comparison to the directive force of the earth's magnetism. That errors have always existed from this cause, may be inferred, from the uncertainty which ex­perience has attached to the results of azimuths observed in ships. The cause, however, appears to have been very long unsuspected, whilst its effects had produced a general impres­sion, that the azimuth compass was in itself an imperfect instrument, and only to be relied on within certain undefined and variable limits.

So deeply is this country in particular interested in whatever may tend to give additional safety to the number of persons, and the immense sums of money employed in commerce, that I trust I shall stand excused for again bringing to the notice of the Royal Society, the subject of the construction of ships. The description of vessels of which I am now about to treat, are those employed in our mercantile service, in the construction of which, the imperfections are such as on a close examination will, I conceive, leave but little doubt that lives and property to an immense amount, must, from time to time, have sacrificed by the present injudicious mode of constructing these ships; and under that impression I have presumed to lay this paper before the Society. And first, as to the principle on which mercantile ships are at present built, and particularly as regards the putting together their ribs or frames, and the arrangement of the materials.

During the course of the year 1814, I had the honour to lay before the Society a paper on the geology of Northumberland and Durham. * It is now my intention to extend that sketch towards the South, taking the Humber and the great north turnpike road for the southern and western boundaries of the district to be described, and the German ocean and the river Tees for the western and northern ones. † It is here proper to remark, that the former are only ideal limits to the formations under consideration; but the latter are real terminations of the rocky strata, a brief account of which will constitute the subject of the following observations. The length of this district is about 60 miles, and its extreme breadth 40; and though the mineral treasures it contains will bear no comparison in respect to number and value with the productions of the country situated to the north and north-west, yet extensive quarries of alum-shale, together with freestone, limestone, chalk, ironstone, and a few thin seams of coal, add in some degree, to the riches of the landed proprietors, and give to many of the poorer inhabitants the means of comfort and support. To begin at the northern extremity of this tract of country, it is necessary to recur to a circumstance mentioned on a former occasion, * viz. that the Tees flows over rocks of fine-grained red and white calcareous sandstones devoid of mica, from a short distance above Croft bridge to the

On the return of the first expedition which sailed for the discovery of a north-west passage, it appeared that from the near approach to the magnetic pole, and the consequent di­-minution of the directive force, the compasses on board had become nearly useless. Some of the azimuth compasses employed on that occasion were of my own invention; I was therefore anxious that the next expedition, which was about to sail under the command of Lieutenant Parry, and which has happily returned with so much honour to those engaged in it, should be furnished with instruments of this description, com­bining as much power and sensibility as possible. It was with this intention alone that I commenced the ex­periments which form the subject of the present paper; but which I should not have deemed sufficiently important to be made public, had I not lately, on resuming the enquiry, been led to some results which appeared of sufficient interest, as well as practical utility, to induce me to lay them before the Royal Society.

The only feasible strategy to minimize pollution from offshore installations is to control the chemicals used. Chemicals are normally only used in response to observed operational problems. They are used in a large number of application areas, and an extensive list of application areas exists. Only a small fraction of chemicals used will eventually reach the marine environment, mainly depending on the water solubility of the chemicals. Since the chemicals discharged are diluted in large quantities of water before and immediately after discharge, the acute toxic effects are considered as not very severe. However, chronic ecotoxicological effects and long-term problems may arise due to accumulation within the marine food chain. Unfortunately, very little information is available on environmental effects of offshore chemicals. However, the harmonizing work which has started within the EEC, requires that new environmental regulations include ecotoxicological data in the classification of chemicals. This important information can be a valuable tool so that operating companies can select alternative chemicals suitable to their operational needs. There is, however, still a need to continue research to develop a suitable methodology to determine possible long-term environmental effects of low solubility chemicals. This paper introduces a research project initiated by Conoco Norway Inc. late 1989.

On Hampton common and at the top of the Stroudwater vale, towards Cirencester, we have a fine oolite, nearly approaching in texture to Bath stone. Beneath the level of the upper oolite, at Uley great quarry, is a mass of bastard-freestone, differing from Bath stone in the abundance and yellowness of the calcareous matter by which it is cemented, and in being more porous and subject to flake after frost. It contains but few shells. Below this freestone are rubbly beds, consisting of compact sparry masses, irregularly shaped like chalk-flints, very full of shells, and separated from one another by a soft calcareous powder, tinged by iron. The tops of Stinchcombe hill and the other hills in its vicinity that flank the valley of the Severn, exhibit vast heaps of rubble, consisting of bastard-freestone mixed with some fragments of pure white oolite. The organic remains that we here find are three or four species of Anomia, Trigonias daedalea and costata, Ostrea crista-galli, and Porpitae. Beneath this debris, in a quarry on the northern side of Stinchcombe hill, under a high beech-wood, we see a few horizontal beds cropping out from beneath others of the above-described rubbly oolite. These beds are of a warm brown colour, and are rather compact in texture, consisting of a sandy loam (such as here prevails upon the surface) cemented by calcareous spar. These beds are divided into strata of moderate thickness. In the beds themselves but few shells can be distinguished; but their joints are

In this paper, we present a dynamic model for simulating a car-like robot with trailer taking into account suspension system and tires deformations. The model describing the wheel/ground contact is a linear model and the joint tractor/trailer is modeled as a spherical-joint. The obtained results are compared with those given by the Pc-Crash software. We noted a good correlation for various scenarios. Furthermore, the proposed model has been successfully applied to study the unbalanced braking in a straight line and the jack-knife problem.

In the brief account of the transit instrument which I had the honour some time ago of presenting to the Royal Society, I stated the circumstance of the instrument's deviation from the meridian arising from the unequal expansion of its braces; but no instance was then given of the magnitude of such deviation. I now subjoin one. On the morning of Oct. 15, (civil reckoning) after observing the passage of Regulus, the southern shutters were accidentally left open, so that when I returned to observe the inferior culmination of the pole star, the sun was shining on the upper western brace, the object-glass of the instrument being towards the zenith. The effect of this was a retardation of more than 25 seconds in the star's passage, as will thus appear: I now view, with great suspicion, all the observations of the sun's transits, which I observed previously to the detection of that source of inequality which is the subject of the present, and of my former communication.

The object of the present communication is to show, by a series of experiments, that the solar rays possess sensible magnetic properties, which are observable in the vibrations of a magnetised needle exposed to those rays, independently of the effects produced by the heat which they impart. I propose likewise to point out the changes which take place in the intensity of a magnetised needle from changes of temperature, as deducible from the times of its vibration. I have before stated in my paper on the effects of temperature on the intensity of magnetic forces , that, in deducing the terrestrial magnetic intensity by means of the vibrations of a needle, a correction ought to be introduced where the observations have been made at different temperatures. I had not at the time made any experiments by which I could ascertain how far changes in the temperature of a needle would be sensible in the time of its vibration; and the first observations which I made with this view being with a light needle, did not give very decided results: they however led me first to notice the very singular fact, that a magnetic needle comes to rest more quickly when vibrated exposed to the rays of the sun, than when vibrated in the shade. In order to ascertain the effect which changes of temperature have on the times of vibration of a needle, it is necessary to know the temperature of the needle itself during the observations, and I saw no better means of ascertaining this, even approximately, than to vibrate it in the shade and then exposed to the rays of the sun, and to consider the temperature of the needle to be that indicated by a thermometer near to it. On my first doing this, I found, that although I could easily mark the 50th vibration when the needle was shaded, I could not distinguish beyond the 40th when it was exposed. I at the same time found that the time of vibration was slightly diminished at the higher temperature, instead of being increased, as I had reason to expect. As however the needle was not vibrated in the same spot in the two cases, the diminution in the time of vibration and of the arc when it was exposed, might be independent of the change of temperature and of any influence in the solar rays. To avoid any uncertainty arising from difference of disturbing causes in two situations, I placed the compass out of doors, with a screen composed intirely of wood, supported at the height of four feet above it, and by removing which the rays of the sun struck directly on the needle. A thermometer having the bulb near to the compass-box indicated nearly the temperature of the needle. When the shutter was up, so that the needle vibrated in the shade, I could very distinctly note the 100th vibration; but when it was removed and the needle vibrated exposed to the sun's rays, I could not so distinctly mark the 75th. I made use of a needle six inches long, weighing 42.75 grains, and contained in a brass compass-box with a glass cover: the needle was suspended by a fine hair, and commenced vibrating 30° from zero.

The attention of the Board of Longitude having been directed to the state of the Solar Tables used in the construction of the Nautical Almanac, the Astronomer Royal was requested to furnish the Board with a comparison of the computed and observed Right Ascensions of the Sun since the erection of the new transit instrument at Greenwich : and I was desired to examine the discrepancies with a view to the discovery of the errors in the elements of the tables. The papers containing this comparison I received at the beginning of June last; and in the last summer, as soon as other engagements permitted, I undertook the laborious work of examining the discordances. The corrections of the elements determined by these calculations agree in general with those that have been obtained from other observations ; but in one particular, and that an important one, there is a very remarkable difference. The results of such an inquiry will perhaps be acceptable to the Royal Society ; and the singularity of the conclusion which I have mentioned, will make it necessary for me to describe the manner in which I have obtained it.

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