bluuebunny/crossref_metadata_2025 huggingface dataset:
Finite Element Analysis Applied to Radial Aircraft Tyre Engineering
Authors: L'Anson R , Peña J , Postic R , Barret J-P
Published: February 2007

The application of finite element analysis (FEA) to the design of radial aircraft tyres is shown to be an effective and efficient tool which can be used for conducting tyre and tyre wheel design studies. This paper describes the specific conditions under which FEA is applied by Michelin to the radial aircraft tyre, and presents an example of its application to the analysis of the tyre and wheel rim contact pressures. Model definition, calculated tyre displacement and rim contact pressure distributions are included. Validation of the FEA prediction against experimental results is demonstrated for a main landing gear tyre.
Deviant Crack Path Behaviour of Aluminium-Lithium Alloy AA8090 Plate
Authors: Gregson P J , Sinclair I
Published: February 2007

The unusual susceptibility of the Al-Li alloy AA8090 to sustained macroscopic deviation of fatigue cracks from a nominal mode I path during conventional fatigue testing is discussed. It is demonstrated that the mixed mode crack growth associated with macroscopic deviation may be characterized in terms of elastic strain energy release rates for a range of mixed mode loading conditions. It is specifically shown that this form of mixed mode crack growth may lead to non-conservative crack growth predictions when these materials are subjected to conventional, mode I based structure lifing techniques.
Electrostatic Suspension System for Gyroscopes with Minimum Electrical Disturbing Torque via Non-Linear Pre-Compensation
Authors: Yang W Q
Published: February 2007

The new electrostatic suspension system (ESS) presented here is applicable to electrostatically suspended gyroscopes (ESG). The electrical disturbing torque (EDT) acting on the gyro rotor is reduced to much lower levels than possible with the conventional methods, thereby increasing the attainable accuracy of the instrument. This is achieved by eliminating the conventional pre-load voltage and instead applying only control voltages via an analogue non-linear pre-compensator to achieve linear position control system operation despite the square law relating the suspension force to the applied voltage. The transient and steady state performance of the complete system, with changes in position reference and external disturbing forces, are examined with the aid of computer simulations.
Boundary Layer Transition Induced by a Von Karman Vortex Street Wake
Authors: Kyriakides N K , Kastrinakis E G , Nychas S G , Goulas A
Published: February 2007

A study has been made of the process of laminar to turbulent transition induced by a von Karman vortex street wake, in the boundary layer on a flat plate. The boundary layer developed under zero pressure gradient conditions while the vortex street was generated by a cylinder positioned in the free stream. Hot-wire measurements over a range of Strouhal frequencies and free stream velocities were used for the identification of the transition onset. From the analysis of the experimental data, two different transition mechanisms known in the literature as ‘strong’ wake and ‘weak’ wake induced transition, could be identified. It was established that, the onset of the strong von Karman wake induced transition process was a function of the free stream velocity, the position of the cylinder with respect to the plate, the cylinder diameter, the drag coefficient and the minimum velocity in the developing wake at the streamwise position of the onset of the boundary layer transition. The end of the strong wake induced transition, was defined at the streamwise distance, where the wake of the cylinder met the wall. A correlation for the prediction of the onset of the transition was developed
Data Bus Technology Applications—Boeing 777 Autothrottle Servo Motor
Authors: Wilkinson D
Published: February 2007

On the Boeing 777 aircraft, two autothrottle actuators are required, one for each throttle lever, both controlled by either one of two computers. The consequent potential need for four remote servo-amplifiers has been eliminated by using two ‘smart’ autothrottle servo motor units (ASMs) independently controlled by ARINC 429 data bus rate command signals from the active computer.

The development of the B777 ASM from a servo motor unit used on B727 is recounted and the ASM design and ARINC 429 data bus control architecture are described in detail.
Aerospace Plane Ascending Trajectories with Heat Consideration
Authors: Al-Garni A Z , Barlow J B
Published: February 2007

This is a study of performance and control for transatmospheric (TAV) aerospace planes, that use air-breathing propulsion. The study is structured in two parts and considers the heat load near the stagnation point. The first part is analytical and consists of two cases, it seeks closed form solutions for the non-linear feedback controls (aerodynamic and thrust), which are necessary to transfer the (TAV) from one specified state to another specified state, while satisfying pairs of equality constraints (that is, Case I: constant acceleration with constant dynamic pressure and Case II: constant rate of climb with constant dynamic pressure). This leads to closed form solutions for the controls in feedback form and also for the heat rate and load. The analytical approach gives a reasonable approximation of the general ascent trajectory to orbit, where the two cases can be used in combination with different constant values of the constraints in different levels of the hypersonic trajectory. The analytical results were a useful guide in the numerical studies. The second part describes numerical simulation and optimization. The control laws, which minimize the heat load, are found in feedback form. A numerical example is worked out for illustration. The trajectory corridor and, in general, all the constraints are satisfied for heat load ≤ 350 kJ/cm2 using feasible controls.
Fin Buffeting Characteristics of a Generic Single Fin Aircraft
Authors: Chesneau T R , Wood N J
Published: February 2007

Experiments have been performed to investigate the fin buffeting characteristics of a generic single fin aircraft. A variety of configurations, including high wing, mid wing and low wing have been examined, some with the addition of leading edge extensions, foreplanes and cheek intakes. The fin buffeting was measured using a flexible fin, which was related to the buffet pressure flowfield using data from an alternative, pressure tapped, rigid fin. Results have been obtained over a wide range of angles of attack at low subsonic speeds.

The production of upstream vortices affects the progression of the primary wing vortex with angle of attack to alter the fin buffeting response. The results indicate that the high wing configurations are sensitive to the presence of additional vortex pairs emanating from forebody features. For low wing configurations, peak buffeting magnitudes may be significantly affected by foreplane incidence in a canard configuration. The interaction between foreplane, wing and body vortices is complex and may result in either reduced or increased levels of buffeting response.
Computer Simulation of the Bi-Stable Valve in the A340 Landing Gear
Authors: Tilley D G , Tomlinson S P
Published: February 2007

The increasing use of simulation for both circuit and component analysis in the aircraft industry has come about due to the requirement for acceptable transient as well as steady state performance of aircraft systems. The computer simulation package, Bathfp, developed at the Fluid Power Centre, University of Bath, is suitable for investigations into both of these. Utilities are provided which allow a model of a complicated system or component to be built up from its elements, which can be introduced to the model library of components so that particular dedicated areas of interest such as flight control actuation systems and braking and landing gear may be examined in detail. Component models enable the internal details of valves, pumps, motors, actuators and other elements to be simulated to a high degree of accuracy.

This paper describes the application of the simulation package to perform a detailed analysis of the bi-stable valve in the A340 landing gear shock absorber. In the original design, a malfunction of the valve during impact on landing was clearly identified by an experimental test. Parametric variations are made in the simulation to identify the possible cause of the malfunction.
Rotorcraft Transmission System HUM Requirements Derived from Design Safety Analysis
Authors: Astridge D G
Published: February 2007

Design safety analysis provides a sound basis for determining the functional requirements of a rotorcraft health and usage monitoring (HUM) system for flight safety purposes, since it considers the vulnerability to catastrophic failure of every component in each safety-critical system. The process thereby identifies the components that may be dependent upon effective monitoring systems in order to achieve the system safety objectives. From the analysis of a new transmission system design, examples are given of component potential failure modes that either (a) are expected to be preventable by direct design action, or (b) will require the additional support of indirect action such as HUM provisions. Many of these examples are expected to be applicable to new rotorcraft transmission designs in general. A brief review of analysis procedures appropriate to rotorcraft transmission systems is included.
Testing Techniques for Chaotic Vibration of Buckled Aircraft Structures
Authors: Ng C F
Published: February 2007

A simple model of non-linear and chaotic dynamic behaviour of buckled plates is presented. Special procedures are described for setting up the tests of flat and buckled plates with vibrations of large amplitude. The difficulties of measuring chaotic motion include the problems in designing the clamping fixtures, controlling the excitation and analysing the results. Case studies of tests with shaker direct attachment, base excitation, and acoustic excitation are used to illustrate the procedures and ways to solve the various problems. The important non-linear dynamic characteristics of curved plates are found to be the transition from softening spring effects to hardening spring effects through the intermediate region of chaotic motion. The chaotic motion is a large amplitude dynamic snap-through motion between the two static buckled positions of the plate.
Ultra-High Molecular Weight Polyethylene Wear Debris Generated in Vivo and in Laboratory Tests; the Influence of Counterface Roughness
Authors: Hailey J L , Ingham E , Stone M , Wroblewski B M , Fisher J
Published: February 2007

The objective of this study was to investigate the effect of counterface roughness and lubricant on the morphology of ultra-high molecular weight polyethylene (UHMWPE) wear debris generated in laboratory wear tests, and to compare this with debris isolated from explanted tissue. Laboratory tests used UHMWPE pins sliding against stainless steel counterfaces. Both water and serum lubricants were used in conjunction with rough and smooth counterfaces. The lubricants and tissue from revision hip surgery were processed to digest the proteins and permit filtration. This involved denaturing the proteins with potassium hydroxide (KOH), sedimentation of any remaining proteins, and further digestion of these proteins with chromic acid. All fractions were then passed through a 0.2 μm membrane, and the debris examined using scanning electron microscopy.

The laboratory studies showed that the major variable influencing debris morphology was counterface roughness. The rougher counter-faces produced larger numbers of smaller particles, with a size range extending below 1 μm. For smooth counterfaces there were fewer of these small particles, and evidence of larger platelets, greater than 10 μm in diameter. Analysis of the debris from explanted tissues showed a wide variation in the particle size distribution, ranging from below 1 μm up to several millimetres in size. Of major clinical significance in relation to osteolysis and loosening is roughening of the femoral components, which may lead to greater numbers of the sub-micron-sized particles.
Three-Dimensional Joint Co-Ordination Strategies of the Upper Limb during Functional Activities
Authors: Barker T M , Nicol A C , Kelly I G , Paul J P
Published: February 2007

A triaxial flexible electrogoniometer has been developed to measure the three-dimensional angular motion of the shoulder joint during simulated activities of daily living. The motion of the elbow, forearm and wrist were also recorded and angle-angle diagrams were mathematically analysed to provide quantitative parameters regarding the control and co-ordination of the joints of the normal and the arthritic upper limb. Two parameters (slope and movement area quotient) were derived and used in the interpretation of joint motion during different activities.
Determination of Lubricating Film Thickness for Permeable Hydrogel and Non-Permeable Polyurethane Layers Bonded to a Rigid Substrate with Articular Reference to Cushion form Hip Joint Replacements
Authors: McClure G , Jin Z M , Fisher J , Tighe B J
Published: February 2007

The lubricating film thickness in a model of compliant layered bearings, using both permeable hydrogels and non-permeable polyurethane elastomers for total hip joint replacements, has been measured using optical interferometry, under both entraining and squeeze-film motion. The film thickness in the lubricated contact was measured for both water and a 40 per cent glycerol solution in water as a function of entraining velocity and squeeze-film time. The measured lubricating film thickness for the permeable hydrogel was compared to that of the non-permeable polyurethane elastomer and little difference was found when the lubricating film thickness was sufficiently large (greater than 150 nm). Comparison of the experimental results and the theoretical predictions based upon elastohydrodynamic lubrication analysis showed good agreement in the entraining experiments where the film thickness was greater than 150 nm. In the squeeze-film experiments the experimental measurements were greater than the theoretical predictions for all squeeze times due to the formation of a central pocket of fluid which was not predicted by the simple theory used. This also occurred for the hydrogels for films greater than 150 nm. For longer squeeze times the film thickness for the hydrogel fell below the theoretical prediction. This was considered to be due to the permeability of the hydrogel reducing the film thickness when the film thickness was less than 150 nm. The permeability of the hydrogel was not modelled in the theoretical lubrication analysis used in this study.
The Influence of Loading Time and Lubricant on the Friction of Articular Cartilage
Authors: Forster H , Fisher J
Published: February 2007

Friction of cartilage on metal, metal on cartilage and cartilage on cartilage contact configurations, within a mixed lubrication regime, was measured using synovial fluid, Ringer's solution or with no lubricant present. The main test variable was the period of stationary loading which ranged from 5 s to 45 min, prior to sliding and consequently measuring friction. The coefficient of friction rose gradually with increasing stationary loading time, up to a value of approximately 0.3 at 45 min for all the contact configurations. Following the re-application of load, after short periods of load removal, friction was also found to drop sharply. The flow of liquid in the biphasic cartilage and load carriage by the fluid phase was highlighted as being an important factor in reducing friction within the mixed or boundary lubrication regime. Movement of the contact zone over the cartilage counterface ensured very low friction as the slider moved over fully hydrated cartilage. For the cartilage-cartilage contacts synovial fluid significantly reduced friction compared to Ringer's solution. This was attributed to an effective boundary lubrication action, which was not as effective for the cartilage-metal contacts. contacts.
Theory and Practice of Meniscal Knee Replacement: Designing against Wear
Authors: O'Connor J J , Goodfellow J W
Published: February 2007

This paper attributes the high rate of high-density polyethylene (HDP) wear in many knee prostheses to incongruity of their articular surfaces. The authors discuss the anatomical and kinematic features of the knee which have led most designers to choose incongruous surfaces and review the reasons for employing free bearings, analogues of the natural menisci, to provide congruity without restriction of movement.

There are theoretical reasons against employing freely mobile bearings in the absence of a functioning anterior cruciate ligament (ACL) and the authors' experience has confirmed this limitation in practice. It is concluded that, in bicompartmental replacement, the movements of the meniscal bearing should be limited in the anteroposterior direction. For unicompartmental arthritis, an unconstrained bearing can be employed if, as is usually the case, all ligaments are intact.
The Influence of Open Leaflet Geometry on the Haemodynamic Flow Characteristics of Polyurethane Trileaflet Artificial Heart Valves
Authors: Corden J , David T , Fisher J
Published: February 2007

In vitro velocity data were obtained downstream of two versions of the Leeds polyurethane trileaflet heart valve in a simulated pulsatile flow regime using laser Doppler velocimetry. The main difference between the two valves studied was the manufacturing method used to create the valves. The film-fabricated valve was constructed from solvent-cast sheets of polyurethane, thermally formed into the correct leaflet geometry. The dip-cast valve used a stainless steel mould which was dipped into a polyurethane solution to produce the valve leaflets. Significant differences were visible between the fully open leaflet shape of each valve. The distribution of mean axial velocity and Reynolds normal stress (RNS) was shown to be dependent on the shape of the fully open valve orifice. For the film-fabricated valves, flow recirculation and high values of RNS were present downstream of the frame posts. The maximum value of RNS obtained downstream of the film-fabricated valve at peak systole was 147 N/m2. Results for the dip-cast valve showed a more uniform distribution of mean axial velocity and RNS resulting from the more circular central orifice produced by the dip-cast leaflets. The maximum value of RNS obtained downstream of the dip-cast valve at peak systole was 109 N/m2. These results demonstrate the effect of the open valve geometry on the flow characteristics downstream of trileaflet valves and that minor changes to the open leaflet geometry can significantly affect the flow characteristics and the possibility of flow-related blood damage occurring in vivo.
A Comparison of the Wear of Cross-Linked Polyethylene against Itself with the Wear of Ultra-High Molecular Weight Polyethylene against Itself
Authors: Joyce T J , Unsworth A
Published: February 2007

Wear tests were carried out on reciprocating pin-on-plate machines which had pins loaded at 10 N and 40 N. The materials tested were irradiated cross-linked polyethylene sliding against itself, irradiated ultra-high molecular weight polyethylene sliding against itself and non-irradiated ultra-high molecular weight polyethylene sliding against itself. After 153.5 km of sliding, the non-irradiated ultrahigh molecular weight polyethylene plates and pins showed mean wear factors under 10 N loads, or a nominal contact stress of 0.51 MPa, of 84.0 × 10−6 mm3/N m for the plates and 81.3 × 10−6 mm3/N m for the pins. Under 40 N loads, or a nominal contact stress of 2.04 MPa, the non-irradiated ultra-high molecular weight polyethylene pins sheared at 22.3 km. At the last measurement point prior to this failure, 19.1 km, wear factors of 158 × 10−6mm3/N m for the plates and 85.0 × 10−6 mm3/N m for the pins had been measured. After 152.8 km, the irradiated ultra-high molecular weight polyethylene plates and pins showed mean wear factors under 10 N loads of 59.8 × 10−6 mm3/N m for the plates and 31.1 × 10−6 mm3/N m for the pins. In contrast, after 150.2 km, a mean wear factor of 0.72 × 10−6 mm3/N m was found for the irradiated cross-linked polyethylene plates compared with 0.053 × 10−6 mm3/N m for the irradiated cross-linked polyethylene pins.
An Approach for the Synthesis of Oil Hydraulic Transmission Line Dynamics Utilizing in situ Measurements
Authors: Watton J , Hawkley C J
Published: February 2007

An approach is developed utilizing measurements of transient pressure and flowrate at the inlet and outlet of the line. A time series analysis technique is used in such a way that the number of unknown coefficients to be estimated is minimized. Accurate predictions are shown for three different line configurations and a range of operating conditions. The evaluation of just two transmission line functions then allows a simple model structure to be used for the simulation of fluid power circuits incorporating long lines.
Improving the Tracking of Generalized Predictive Control Controllers
Authors: Rossiter J A , Grinnell B G
Published: February 2007

One of the advantages of predictive control is its ability to take optimal account of information about future set point changes in the specification of the control law. However, the optimum GPC (generalized predictive control) prefilter that uses this information can lead to a deterioration rather than an improvement in the accuracy of tracking. Some simple modifications to GPC to overcome this problem are discussed. It will then be shown how some simple algorithms can be used to design an optimal prefilter that does not have any of the poor effects arising from the standard choice and hence always improves the performance. The basis of the technique is analogous to the two-degree-of-freedom designs common in the literature on H∞. However, here the emphasis is on fixed-order prefilters designed from a time domain, not a frequency domain, objective.
A Fuzzy Logic Approach in the Control of a Twin-Spool Aircraft Gas Turbine Engine under Development
Authors: Balakrishnan S R , Santhakumar S
Published: February 2007

The advantages of a rule-based fuzzy controller with its well-established benefits of system representation in intuitive terms, ease of development and modification, ease of inputs selection, output interpolation and robustness are investigated with special reference to an aircraft gas turbine engine. This approach has a distinct advantage in the engine development phase, during which a precise model of the complex plant is unlikely to be available. The desirability of a deadbeat response for certain variables with constraints on some of these is highlighted. The design of a rule-based fuzzy controller for a twin-spool aircraft gas turbine engine with excellent response characteristics is outlined in this paper. Simulation results with a thermodynamic model of the engine using the fuzzy controller are presented. Responses obtained at representative points of a flight envelope and results from a comparison study with a proportional integral derivative (PID) controller are also presented.
Thrust Cone Lubrication: Part 3: A Test Facility and Preliminary Measured Data
Authors: Parkins D W , Rudd L
Published: February 2007

This paper describes a unique facility for measuring the film thickness in thrust cone bearings. Full details are given of the design approach and specified characteristics, together with the resultant configuration and its attributes. Some preliminary results are included which indicate the relative capacity of flat and crowned thrust cones and the implications for operation with misaligned rotational axes.
Tribology Research in Japan—A State-of-the-Art Report
Authors: Kimura Y , Tanaka M , Enomoto Y
Published: February 2007

This paper is a state-of-the-art report on tribology research presented or published in Japan recently, and covers a wide variety of topics that the authors consider are interesting and should be focused on. This article hopefully can give readers a general view of recent activities of Japanese tribologists and what they are now interested in.
Determination of Viscosity and Pressure in an Elastohydrodynamic Rolling Contact by using Optical Interferometry: A Theoretical Study
Authors: Östensen J O , Larsson R , Venner C H
Published: February 2007

Optical interferometry has been used during the last 30 years for film thickness measurements in elastohydrodynamic (EHD) contacts. In the work presented in this paper the possibility of using optical interferometry for determining pressure and apparent viscosity in a fully flooded EHD point contact has been theoretically investigated. The pressure in the contact is computed from elastic deformation theory and force balance. The apparent viscosity can be obtained from the Reynolds equation when the film thickness and the pressure are known. To theoretically examine the sensitivity to measurement errors, different errors have been implemented in a set of ‘exact’ numerical data.

From the theoretical study it can be seen that a film thickness map obtained from optical interferometry can be used for determination of both pressure and apparent viscosity measurement in an EHD point contact. The simulated errors that have been used do not influence the pressure within the Herzian region by more than a few per cent. However, to obtain reliable results from the apparent viscosity calculations, the measurements of film thickness, load and elastic modulus must be very accurate. It is seen, for example, that the resolution of the film thickness measurement has to be less than 1 nm to achieve high accuracy.
Continuous-Time Markov Decision Processes with Discounted Rewards: The Case of Polish Spaces
Authors: Guo Xianping
Published: February 2007

This paper deals with continuous-time Markov decision processes in Polish spaces, under an expected discounted reward criterion. The transition rates of underlying continuous-time jump Markov processes are allowed to be unbounded, and the reward rates may have neither upper nor lower bounds. We first give conditions on the controlled system’s primitive data. Under these conditions we prove that the transition functions of possibly nonhomogeneous continuous-time Markov processes are regular by using Feller’s construction approach to such transition functions. Then, under additional continuity and compactness conditions, we ensure the existence of optimal stationary policies by using the technique of extended infinitesimal operators associated with the transition functions, and also provide a recursive way to compute (or at least to approximate) the optimal reward values. Finally, we use examples to illustrate our results and the gap between our conditions and those in the previous literature.
Stochastic Integer Programming: Limit Theorems and Confidence Intervals
Authors: Eichhorn Andreas , Römisch Werner
Published: February 2007

We consider empirical approximations (sample average approximations) of two-stage stochastic mixed-integer linear programs and derive central limit theorems for the objectives and optimal values. The limit theorems are based on empirical process theory and the functional delta method. We also show how these limit theorems can be used to derive confidence intervals for optimal values via resampling methods (bootstrap, subsampling).
On the Starting and Stopping Problem: Application in Reversible Investments
Authors: Hamadène Said , Jeanblanc Monique
Published: February 2007

In this work, we solve completely the starting and stopping problem when the dynamics of the system are a general adapted stochastic process. We use backward stochastic differential equations (BSDEs) and Snell envelopes. Finally, we give some numerical results.
Schizophrenia: Multi-Attribute Utility Theory Approach to Selection of Atypical Antipsychotics
Authors: Bettinger Tawny L , Shuler Garyn , Jones Donnamaria R , Wilson James P
Published: February 2007

Background:

Current guidelines/algorithms recommend atypical antipsychotics as first-line agents for the treatment of schizophrenia. Because there are extensive healthcare costs associated with the treatment of schizophrenia, many institutions and health systems are faced with making restrictive formulary decisions regarding the use of atypical antipsychotics. Often, medication acquisition costs are the driving force behind formulary decisions, while other treatment factors are not considered.

Objective:

To apply a multi-attribute utility theory (MAUT) analysis to aid in the selection of a preferred agent among the atypical antipsychotics for the treatment of schizophrenia.

Methods:

Five atypical antipsychotics (risperidone, olanzapine, quetiapine, ziprasidone, aripiprazole) were selected as the alternative agents to be included in the MAUT analysis. The attributes identified for inclusion in the analysis were efficacy, adverse effects, cost, and adherence, with relative weights of 35%, 35%, 20%, and 10%, respectively. For each agent, attribute scores were calculated, weighted, and then summed to generate a total utility score. The agent with the highest total utility score was considered the preferred agent.

Results:

Aripiprazole, with a total utility score of 75.8, was the alternative agent with the highest total utility score in this model. This was followed by ziprasidone, risperidone, and quetiapine, with total utility scores of 71.8, 69.0, and 65.9, respectively. Olanzapine received the lowest total utility score. A sensitivity analysis was performed and failed to displace aripiprazole as the agent with the highest total utility score.

Conclusions:

This model suggests that aripiprazole should be considered a preferred agent for the treatment of schizophrenia unless found to be otherwise inappropriate.
Restoration challenges for urban rivers
Authors: D'Arcy B.J. , Rosenqvist T. , Mitchell G. , Kellagher R. , Billett S.
Published: February 2007

Urban sources account for significant quantities of important diffuse pollutants, and urban watercourses are typically badly polluted. As well as toxic metals, hydrocarbons including PAHs, and suspended matter, priority urban pollutants include faecal pathogens and nutrients. Can urban watercourses be restored by sufficient reductions in pollution loads? Case studies in the UK and Sweden provide insights and some grounds for optimism. A major trans-Atlantic review of the performance of best management practices (BMPs) is informing BMP planning. New approaches such as the maximisation of self-purification capacity in the receiving waters may also need to be developed, alongside BMPs at source. Other initiatives in Europe, USA and China, including collaborative projects, are trying to address the intractable issues such as persistent pollutants from transport and urban infrastructure. The challenge is daunting, but there are clear ways forward and future research needs are evident.
Diffuse pollution associated with the mining sectors in South Africa: a first-order assessment
Authors: Coetser S.E. , Heath R.G.M. , Ndombe N.
Published: February 2007

Internationally it has become recognised that diffuse source water pollution from mining activities severely affects the degradation of water quality especially with regards to acidification and metal loading. South Africa is facing major problems with regard to the management and treatment of contaminated mine water. Very little has been published for South Africa about the quantities and qualities of diffuse source water pollution by the mining industry. Furthermore the available information has not yet been compiled into a consolidated overview that presents the total picture. Some of the problems that limit the use of the available information and would necessitate further processing to normalise the data, derive from the fact that the investigations producing the information were done at different times, to different levels of detail and using different approaches. A further complicating factor is that data for some mining commodities may not be available and may necessitate further investigation. The overview of the quantities and qualities of non-point source effluent production by different sectors needs to be interpreted in terms of the effect the effluent can be expected to have on receiving water quality (both surface and groundwater). It would thus be necessary to categorise waste types according to their effect on water quality and synthesise the data to obtain an estimate of the threat that different sectors and sub-sectors pose to receiving water quality.
Diffuse pollution from intensive agriculture: sustainability, challenges, and opportunities
Authors: Burkart M.R.
Published: February 2007

Global expansion and intensification of industrialized agriculture during the last 50 years was facilitated by the replacement of labor by imported chemicals and energy, thus changing the economics and the social fabric of rural communities as well as impairing water, air, and soil resources essential to sustaining food and fiber production in a world with an increasing appetite. To effectively understand and solve complex problems resulting from this agricultural revolution, expanded communications are needed at a variety of levels. It is critical for the technical community to communicate through greater interdisciplinary research among agronomists, soil scientists, hydrologists, ecologists, and others to reduce diffuse pollution from agriculture. Also, more effective translations of technical problems and solutions are needed to influence policy. Accurate advice is needed in spite of the uncertainties that scientists too often use to obscure useful information. Education will be needed for producers and conservationists to gain confidence that promised environmental responses will occur if solutions are to be implemented at more than experimental or demonstration scales. The search for comprehensive solutions to environmental degradation will require understanding the ultimate causes of pollution, not just the proximal causes. The ultimate causes will only be found by examining the systems that facilitate the release of contaminants to the environment such as the wholesale landscape changes that replaced grazing land with annual crops leading to increased leaching and runoff. Research and demonstration projects increasingly need collaborations among agronomists, livestock scientists, soil scientists, hydrologists, economists, sociologists and others who have a stake in the study of diffuse pollution and the outcomes of any proposed solutions. Partnerships developed at the working level where basic principles can be shared will help avoid the pursuit of impractical solutions when viewed from different perspectives.
The influence of diffuse pollution on groundwater content patterns for the groundwater bodies of Germany
Authors: Kunkel R. , Wendland F. , Hannappel S. , Voigt H.J. , Wolter R.
Published: February 2007

Commissioned by Germany's Working Group of the Federal States on Water Problems (LAWA) the authors developed a procedure to define natural groundwater conditions from groundwater monitoring data. The distribution pattern of a specific groundwater parameter observed by a number of groundwater monitoring stations within a petrographically comparable groundwater typology is reproduced by two statistical distribution functions, representing the “natural” and “influenced” component. The range of natural groundwater concentrations is characterized by confidence intervals of the distribution function of the natural component. The applicability of the approach was established for 17 hydrochemical different groundwater typologies occurring throughout Germany. Based on groundwater monitoring data from ca. 26,000 groundwater-monitoring stations, 40 different hydrochemical parameters were evaluated for each groundwater typology. For all investigated parameters the range of natural groundwater concentrations has been identified. According to the requirements of the EC Water Framework Directive (article 17) (WFD) this study is a basis for the German position to propose criteria for assessing a reference state for a “good groundwater chemical status”.
Water fluxes and diffuse nitrate pollution at river basin scale: coupling of agro-economic models and hydrological approaches
Authors: Wendland F. , Kunkel R. , Bogena H. , Gömann H. , Kreins P.
Published: February 2007

An integrated model system has been developed to estimate the impact of nitrogen reduction measures on the nitrogen load in groundwater and in river catchment areas. The focus lies on an area-wide, regionally differentiated, consistent link-up between the indicator “nitrogen balance surplus” and nitrogen charges into surface waters. As a starting point of the analysis actual nitrogen surpluses in the soil were quantified using the agro-economic RAUMIS-model, which considers the most important N-inputs to the soil and N-removals from the soil through crop harvest. The most important pathways for diffuse nitrogen inputs into river systems are modelled with the water balance model GROWA. Additionally, the time-dependent nitrogen degradation along the nitrogen pathways in soil and groundwater are modelled using the WEKU-model. The two selected river basins in Germany cover a variety of landscape units with different hydrological, hydrogeological and socio-economic characteristics. The results indicate a wide range of annual nitrogen surpluses for the rural areas between than 10 kg N ha−1•a−1 and 200 kg N ha−1•a−1 or more, depending on the type and intensity of farming. The level of nitrogen inputs into the surface waters is reduced because of degradation processes during transport in soil and groundwater. Policy impact analyses for a nitrogen tax and a limitation of the livestock density stress the importance of regionally adjusted measures.
Assessment of point and non-point pollution associated with the power generation sector in South Africa
Authors: van Zyl H.D. , Heath R.G.
Published: February 2007

Access to water and water availability remains a key factor in ensuring the sustainability of development in Southern Africa. The need for guidelines to improve management of this valuable resource, and to regulate pollutant discharge, is therefore of national interest.

A new and growing threat to our natural water resources is non-point source (NPS) pollution. The important distinction between point pollution and NPS pollution is that the latter is difficult to identify and the entry point of contamination to resources is diffuse and not limited to a single location. NPS pollution associated with power generation includes, but is not limited to, atmospheric deposition resulting from emissions (air and water), leachate from coal storage piles and runoff from impervious areas which are covered with dust fallout from coal and ash handling operations. Emissions of primary concern are sulfur, nitrogen and mercury.
Water quality estimation in consideration of pollutant runoff and internal production in Lake Biwa, Japan
Authors: Ichiki A. , Nakakura K. , Sakata N. , Sasaki A. , Tai Y.
Published: February 2007

Lake Biwa is the largest lake in Japan, and water quality in the lake is heterogeneous. Therefore, it is important for water quality management that spatial distribution of water quality in the lake should be clearly understood. The objectives of this study are to show a methodology and to develop a simulation system to calculate COD distribution in Lake Biwa taking internal COD production into consideration. This study also aims to examine transition of COD in the lake using the simulation system. In the simulation system, runoff loads of COD from the Lake Biwa basin are calculated by Macro Model for each tributary. The external COD concentration in 233 inshore meshes of the Lake Biwa water surface was calculated using the runoff loads. The internal COD was calculated using relationships among limiting nutrients, chlorophyll-a and COD. Then, the spatial distribution of water quality in Lake Biwa was calculated both for the external and internal COD by spline technique. Simulations using the system were implemented for 1986–1998, and a clear difference in characteristics between a drought year and a flood year was shown. In the result, it was shown that the simulation system developed here was available to calculate COD distribution in Lake Biwa, and that it had the possibility to explain the recent phenomenon of COD increase in the lake.
Carcinosarcoma of the spleen: literature review of a very rare tumour
Authors: Rao Annapurna , Mathew George , Marimuthu Kalimuthu , Pandey Urmila , Worlding Jane
Published: February 2007

Carcinosarcomas are rare tumours, which have both epithelial, and connective tissue elements. They are most commonly seen in the female genital tract. Rarely they arise from the gastrointestinal tract. We report a case of Carcinosarcoma arising as a primary in the spleen of a male aged 60yrs. The most unique feature of this tumour is the presence of osteosarcomatous element. This report highlights the importance of clinical awareness of such rare tumours and gives a brief overview on presentation, probable aetiology, diagnosis and management with literature review of carcinosarcoma.
Are Ottawa knee rules useful in actual trauma care?
Authors: Nagpal Kamal , Marathe Mandar
Published: February 2007

Acute knee injuries are a common presentation to the emergency department(ED). Ottawa knee rules (OKR) have shown to reduce the number of radiographs in these patients in North American studies and a fracture rate of 5% has been reported. Based on this, we tested the hypothesis that it was possible to decrease the number of x-ray films obtained after a knee trauma without delayed fracture diagnosis by means of the Ottawa knee rules in British set up. A total of 118 adult patients with acute Knee injuries were studied. A checklist in an easy-to-use format was produced to act as an aide-memoir and to encourage clinicians to apply the OKR in their decision making. Sixty patients were studied before introducing the check list stickers of OKR and fifty eight were studied after introducing the stickers. The OKR were found to have been obeyed in 24 (40%) of patients in the group which did not have stickers. In the group assessed without an OKR sticker, 28 (46.7%) of patients had knee radiography, compared with 29 (50%) of patients in the group who were assessed with an OKR sticker. There was no decrease in the number of x-rays after following the Ottawa Knee Rules (OKR).
Breast cancer incidence and mortality in Lower Silesia (Poland) between 1984 and 2003 — trends and perspectives
Authors: Bębenek Marek , Pudełko Marek , Błaszczyk Jerzy
Published: February 2007

The purpose of the study was to determine the epidemiological characteristics of breast cancers diagnosed among Lower Silesian women between 1984 and 2003. Data from the Lower Silesian Cancer Registry on the incidence and mortality of breast neoplasms in the Lower Silesian province were analyzed. The annual number of breast cancers and cancer-related deaths increased markedly between 1984 and 2003. The non-standardized coefficients of incidence in the large cities of Wroclaw, Legnica, and Walbrzych were markedly higher than in the other counties of the province. The number of tumors detected with diameters ≤5 cm increased from 57% in 1984 to 81% in 2003. The increasing incidence of breast cancer seemed to be mostly related to the socioeconomic characteristics of Lower Silesian women. Although a down-staging due to better care reflects some positive trends, the outlook for breast cancer in Lower Silesia remains unfavorable.
Deterministic global optimization of nonlinear dynamic systems
Authors: Lin Youdong , Stadtherr Mark A.
Published: February 2007

A new approach is described for the deterministic global optimization of dynamic systems, including optimal control problems. The method is based on interval analysis and Taylor models and employs a type of sequential approach. A key feature of the method is the use of a new validated solver for parametric ODEs, which is used to produce guaranteed bounds on the solutions of dynamic systems with interval‐valued parameters. This is combined with a new technique for domain reduction based on the use of Taylor models in an efficient constraint propagation scheme. The result is that an ϵ‐global optimum can be found with both mathematical and computational certainty. Computational studies on benchmark problems are presented showing that this new approach provides significant improvements in computational efficiency, well over an order of magnitude in most cases, relative to other recently described methods. © 2007 American Institute of Chemical Engineers AIChE J, 2007
Intrapulmonary lymph nodes in South African miners—an autopsy survey
Authors: Honma Koichi , Nelson Gill , Murray Jill
Published: February 2007

Background

Knowledge on intrapulmonary lymph nodes (IPLNs) is still limited. Progress in imaging techniques has enabled easier, more frequent visualization of IPLNs so that a more comprehensive understanding of these nodes is necessary.

Methods

Microscopic slides of lung tissue from 2,337 dust‐exposed South African miners autopsied in 1975 were reviewed to identify IPLNs. The prevalence of IPLNs was calculated and histopathological changes in IPLNs and the surrounding lung parenchyma were described. Pathological changes of IPLNs were correlated with those of the surrounding pulmonary parenchyma.

Results

IPLNs were found in 86 of the miners (3.7%). Silicotic nodules were seen in IPLNs in 32 of the 86 cases (37.2%), in the majority of which (21/32; 65.6%) the surrounding lung parenchyma was almost normal.

Conclusion

IPLNs are not uncommon among dust‐exposed individuals. Silicotic fibrosis of IPLNs appears to precede pulmonary parenchymal disease. Am. J. Ind. Med. 2007. © 2007 Wiley‐Liss, Inc.
Female fertility and childbirth after ileal pouch–anal anastomosis for ulcerative colitis
Authors: Lepistö A , Sarna S , Tiitinen A , Järvinen H J
Published: February 2007

Background

The aim of this study was to calculate the probability of becoming pregnant after ileal pouch–anal anastomosis (IPAA) for ulcerative colitis, and to evaluate complications during pregnancy and childbirth.

Methods

A questionnaire was posted to 160 women with an IPAA and to 160 controls. The probability of becoming pregnant after IPAA was calculated by the Kaplan–Meier method.

Results

Of 54 women who had undergone IPAA surgery, 36 (67 per cent) succeeded in becoming pregnant naturally, compared with 49 (82 per cent) of 60 controls. The probability of pregnancy after 2 years of trying was 56 per cent in the IPAA group and 91 per cent in the control group (P < 0·001). Women in the IPAA group needed infertility investigations more often (24 versus 10 per cent; P = 0·044). In all, 39 (72 per cent) women in the IPAA group and 53 (88 per cent) in the control group bore a child. Twenty-one of 39 women in the IPAA group and 13 of 53 in the control group had a caesarean section (P = 0·005). Anal incontinence after delivery occurred more often in the control group.

Conclusion

Women with an IPAA mostly suffer a reduction in the probability of conception rather than complete infertility. Because complications during pregnancy and delivery were rare, caesarean section should be based mainly on obstetric indications.
Phytotoxicity of Secondary Metabolites from Aptenia cordifolia
Authors: DellaGreca Marina , Fiorentino Antonio , Izzo Angelina , Napoli Filomena , Purcaro Raffaella , Zarrelli Armando
Published: February 2007

From the fresh leaves or twigs of Aptenia cordifolia, a total of 29 compounds were isolated, including the new tetranoroxyneolignan 18, the new dilignan 19, and the β‐ionone derivative 27, previously only known as a synthetic compound, together with 26 known compounds. The structures of the new products were determined by 1H‐, 13C‐, and 2D‐NMR, as well as HR‐MS analyses. The phytotoxic effects of the isolates on the germination and growth of the dicotyledon Lactuca sativa L. (lettuce) were studied in the concentration range 10−4 to 10−7 M. Several constituents of A. cordifolia were found to be equally active as or superior to 4‐hydroxybenzoic acid (HBA) used as positive control.