Search

Frederick Edward (‘Ned’) Warner's childhood home was a London County Council flat in north London. He won a scholarship to Bancroft's School, where he was successful in both academic and sporting activities and was awarded an Exhibition to read chemistry at University College London. Following this chemistry degree he took a diploma in chemical engineering. Sport, debates and left-wing politics dominated his student years. Warner was at the forefront in developing health, safety, risk assessment and environmental policies, particularly in their implementation to chemical process plant; early professional experience in several chemical manufacturing companies and extensive wartime work associated with acid manufacture had driven this commitment. He was a leading figure in the creation of the consulting company Cremer and Warner, and was appointed court expert to the Court of Enquiry following the Flixborough explosion in 1974. As treasurer of the Scientific Committee on Problems of the Environment, he chaired three of its major projects: Environmental Consequences of Nuclear War; Pathways of Artificial Radionucleotides; and Radiation from Nuclear Test Explosions. His expertise in the environmental effects of radiation put him in a position to lead the first international team to Chernobyl after the reactor meltdown in 1986. Warner served on many governmental, professional and academic bodies, particularly the Institution of Chemical Engineers, of which he was president in 1966–1967. He was knighted in 1968 for services to chemical engineering, was elected to the Royal Society in 1976 and was a founder fellow of the Fellowship of Engineering (now the Royal Academy of Engineering). He died in 2010, aged 100.

Background Brown adipose tissue (BAT) is a fat tissue found in most mammals that helps regulate energy balance and core body temperature through a sympathetic process known as non-shivering thermogenesis. BAT activity is commonly detected and quantified in [18F]FDG positron emission tomography/computed tomography (PET/CT) scans, and radiotracer uptake in BAT during adrenergic stimulation is often used as a surrogate measure for identifying thermogenic activity in the tissue. BAT thermogenesis is believed to be contingent upon the expression of the protein UCP1, but conflicting results have been reported in the literature concerning [18F]FDG uptake within BAT of mice with and without UCP1. Differences in animal handling techniques such as feeding status, type of anesthetic, type of BAT stimulation, and estrogen levels were identified as possible confounding variables for [18F]FDG uptake. In this study, we aimed to assess differences in BAT [18F]FDG uptake between wild-type and UCP1-knockout mice using a protocol that minimizes possible variations in BAT stimulation caused by different stress responses to mouse handling. Results [18F]FDG PET/CT scans were run on mice that were anesthetized with pentobarbital after stimulation of non-shivering thermogenesis by norepinephrine. While in wild-type mice [18F]FDG uptake in BAT increased significantly with norepinephrine stimulation of BAT, there was no consistent change in [18F]FDG uptake in BAT of mice lacking UCP1. Conclusions [18F]FDG uptake within adrenergically stimulated BAT of wild-type and UCP1-knockout mice can significantly vary such that an [18F]FDG uptake threshold cannot be used to differentiate wild-type from UCP1-knockout mice. However, while an increase in BAT [18F]FDG uptake during adrenergic stimulation is consistently observed in wild-type mice, in UCP1-knockout mice [18F]FDG uptake in BAT seems to be independent of β3-adrenergic stimulation of non-shivering thermogenesis.

BackgroundBrown adipose tissue (BAT) is a fat tissue found in most mammals that helps regulate energy balance and core body temperature through a sympathetic process known as non-shivering thermogenesis. BAT activity is commonly detected and quantified in 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) scans, and radiotracer uptake in BAT during adrenergic stimulation is often used as a surrogate measure for identifying thermogenic activity in the tissue. BAT thermogenesis is believed to be contingent upon the expression of the protein UCP1, but conflicting results have been reported in the literature concerning 18F-FDG uptake within BAT of mice with and without UCP1. Differences in animal handling techniques such as feeding status, type of anesthetic, type of BAT stimulation, and estrogen levels were identified as possible confounding variables for 18F-FDG uptake. In this study, we aimed to assess differences in BAT 18F-FDG uptake between wildtype and UCP1-knockout mice using a protocol that minimizes possible variations in BAT stimulation caused by different stress responses to mouse handling.Results18F-FDG PET/CT scans were ran on mice that were anesthetized with pentobarbital after stimulation of non-shivering thermogenesis by norepinephrine. While in wild type mice 18F-FDG uptake in BAT increased significantly with norepinephrine stimulation of BAT, there was no consistent change in 18F-FDG uptake in BAT of mice lacking UCP1. Conclusions18F-FDG uptake within adrenergically stimulated BAT of wildtype and UCP1-knockout mice can significantly vary such that an 18F-FDG uptake threshold cannot be used to differentiate wildtype from UCP1-knockout mice. However, while an increase in BAT 18F-FDG uptake during adrenergic stimulation is consistently observed in wild type mice, in UCP1-knockout mice 18F-FDG uptake in BAT seems to be is independent of β3 adrenergic stimulation of non-shivering thermogenesis.

Purpose A process improvement sampling methodology, known as process variation diagnostic tool (PROVADT), was proposed by Cox et al. (2013). The method was designed to support the objectivity of Six Sigma projects performing the measure-analyse phases of the define-measure-analyse-improve-control cycle. An issue in PROVADT is that it is unable to distinguish between measurement and product variation in the presence of a poor Gage repeatability and reproducibility (R&R) result. The purpose of this paper is to improve and address PROVADT’s sampling structure by enabling a true Gage R&R as part of its design. Design/methodology/approach This paper derives an enhanced PROVADT method by examining the theoretical sampling constraints required to perform a Gage R&R study. The original PROVADT method is then extended to fulfil these requirements. To test this enhanced approach, it was applied first to a simulated manufacturing process and then in two industry case studies. Findings The results in this paper demonstrates that enhanced PROVADT was able to achieve a full Gage R&R result. This required 20 additional measurements when compared to the original method, but saved up to ten additional products and 20 additional measurements being taken in future experiments if the original method failed to obtain a valid Gage R&R. These benefits were highlighted in simulation and industry case studies. Originality/value The work into the PROVADT method aims to improve the objectivity of early Six Sigma analyses of quality issues, which has documented issues.

Purpose – The purpose of this paper is to examine the efficiency and objectivity of current Six Sigma practices when at the measure/analyse phase of the DMAIC quality improvement cycle. Design/methodology/approach – A new method, named process variation diagnostic tool (PROVADT), demonstrates how tools from other quality disciplines can be used within the Six Sigma framework to strengthen the overall approach by means of improved objectivity and efficient selection of samples. Findings – From a structured sample of 20 products, PROVADT was able to apply a Gage R&R and provisional process capability study fulfilling the pre-requisites of the measure and early analyse phases of the DMAIC quality improvement cycle. From the same sample, Shainin multi-vari and isoplot studies were conducted in order to further the analysis without the need of additional samples. Practical implications – The method was tested in three different industrial situations. In all cases PROVADT's effectiveness was shown at driving forward a quality initiative with a relatively small number of samples. Particularly in the third case, it lead to the resolution of a long standing complex quality problem without the need for active experimentation on the process. Originality/value – This work demonstrates the need to provide industry with new statistical tools which are practical and give users efficient insight into potential causes of a process problem. PROVADT makes use of data needed by quality standards and Six Sigma initiatives to fulfil their requirements but structures data collection in a novel way to gain more information.

The main focus of this paper is to use discrete-event simulation models, to test the robustness of two process control methods against processes with different statistical distributions. The two methods under scrutiny are the Small-Batch Full-size image (3 K) & R chart and the Set-Up Process Algorithm (SUPA). These have been developed for ‘setup dominant processes’, were the major source of product variation is detected between batches. Minimizing this type of variation is critical to ensure spare parts produced at a later date will fit in operating assemblies, maintaining a Through-life Engineering Service. This paper shows their suitability to industry.

Detailed analysis of stability and bifurcation properties and of the dynamic behaviour of isothermal continuous mixed suspension, mixed product removal (CMSMPR) crystallizers is presented using the moment equation model. It is shown that isothermal CMSMPR crystallizers may exhibit not only limit cycle oscillations but, in the case of magma-dependent nucleation, also saddle point instabilities. Applying the Mikhailov stability criterion, two equivalent sets of necessary and sufficient conditions are derived for checking the stability of steady states. Stability maps are presented in the planes of different pairs of system parameters. It is shown that saddle node and boundary bifurcation, as well as bifurcation at infinity may arise in the case of magma-dependent secondary nucleation. Oscillations of the population density and distribution functions are also presented and analysed, approximating the size distribution by gamma distribution. In dynamic states, the crystal size distribution may differ significantly from the exponential one, while the mean values of oscillations of supersaturation are lower than the corresponding steady state values. A causal loop diagram between the variables reveals that instabilities are created by the interactions of the autoinhibition generated negative feedback and a positive feedback between the four leading moments of crystal size.

This paper presents a comprehensive set of theoretical investigations and industrial applications of computer-based rapid manufacturing technology for high-integrity aerospace components. Two rapid manufacturing processes have been proposed by integrating rapid prototyping, high-speed machining (HSM), reverse engineering and geometric computation theory. They have been validated through trial manufacturing of a matrix of current aerospace components embracing critical design features to be found across the aerospace industry. Applied to future development programmes, this research will provide aerospace companies the benefits of significant decrease in product introduction lead-time, savings in non-recurring product introduction costs and considerable reduction in manufacturing costs for “one off” and low volume service parts. The findings can also be applied to rapid prototype development in other industries, such as automotive and military.

To better understand the complicated phenomena in a precipitation process, computational fluid dynamics (CFD) is utilized to account for reactions, crystallization, mixing, and their interactions. The moment transformations of the population balances taking into account the chemical and crystallization kinetics are integrated into a CFD solver to describe the generation and transportation of the crystal phase. The current work applies this CFD tool to simulate the reactive precipitation process in a semibatch crystallizer, which is widely used in chemical and pharmaceutical industries. BaSO4 precipitation is employed as an example system. The influence of hydrodynamics in the stirred tank, as characterized by the impeller speed and feed location, on the distribution of supersaturation and the subsequent crystal size distribution is investigated. The numerical predictions are validated with measurements and can be used as an aid in the optimization of semibatch precipitator design.

We present a mathematical model describing the inward solidification of a slab, a circular cylinder and a sphere of binary melt kept below its equilibrium freezing temperature. The thermal and physical properties of the melt and solid are assumed to be identical. An asymptotic method, valid in the limit of large Stefan number J, is used to decompose the moving boundary problem for a pure substance into a hierarchy of fixed-domain diffusion problems. Approximate, analytical solutions are derived for the inward solidification of a slab and a sphere of a binary melt which are compared with numerical solutions of the unapproximated system. The solutions are found to agree within the appropriate asymptotic regime of large Stefan number and small time. Numerical solutions are used to demonstrate the dependence of the solidification process upon the level of impurity and other parameters. We conclude with a discussion of the solutions obtained, their stability and possible extensions and refinements of our study. (C) 2001 Elsevier Science Ltd. AH rights reserved.

This article looks at the development of a practical model for change management, based on a collation of best practices from several organisations. The model focuses on five key success factors thought to be the drivers for successful change: commitment, social and cultural issues, communication, tools and methodology and interactions. The potential use of this model is explored, with the conclusion that it can provide any organisation with a structured and measurable method for improving the way in which it manages change. It can be applied at several levels within an organisation and, therefore, has the potential to help everyone involved in change.

The use of emulsions as a means of studying the kinetics of homogeneous nucleation has been well known for a number of years. In this contribution, however, attention is given to the possible use of emulsions in novel process technology, on the one hand as a means of directing the size and morphology of particulate materials and on the other as the basis for melt purification. m-Chloronitrobenzene serves as a model compound in this work, although the central concepts are valid for any low melting molecular material. Particular attention has been paid to the choice and mode of action of the emulsifier since it is this which ultimately controls the outcome of the crystallization process.

A CFD package was employed to simulate the steady state precipitation of barium sulphate in jet mixing devices (coaxial flow pipeline mixers and tee-junction mixers). Both 2D and 3D descriptions were employed. Solutions of the Navier-Stokes equations along with the standard two equation k-e turbulence model provide the velocity and energy fields while generation and development of the solid crystal phase were described by the moment equations of the population balance. Spatial distributions of species concentrations, supersaturation, total crystal number and magma density were calculated and the average size and coefficient of variation of the crystal product determined. Visualization of these distributions enables a rapid assessment of the effect of the actual flow pattern within a particular jet precipitator. The influence of the positions and orientation of the two inlet streams, as well as the length of the mixer on the mixing and the precipitation were investigated.

The influence of four homologous additives, docosane, tricosane, pentacosane and hexacosane, on the nucleation and crystal growth processes of tetracosane in dodecane solutions was characterized through measurements of induction periods and overall nucleation and growth kinetics. Kinetic results indicate that the effects of the four additives on the nucleation and growth processes of tetracosane depend greatly on the carbon chain length of the additive; for systems with docosane, pentacosane or hexacosane as additives, the nucleation rates are much lower than in pure systems at the same overall growth rate, whereas tricosane gives no significant difference in the nucleation and growth rates. Evidence from the induction periods shows that only pentacosane and hexacosane appear to suppress the nucleation process of tetracosane while docosane and tricosane as additives produce no significant difference.

Emulsion crystallisation has been investigated in order to assess its potential use both in the material science context, as a means of particle preparation and in the context of new purification processes.

The growth habit of 6-APA crystals was characterized for growth from pure solution and from solutions containing equimolar concentrations of phenoxyacetic acid (PHOX). From pure solutions 6-APA crystallizes as thin diamond-shaped plates bounded mainly by {020} and {101} faces. Growth in the 〈002〉 direction is rapid relative to that in 〈200〉. Growth in the presence of PHOX produces dramatic changes in morphology, elongated plates or needle-like crystals with well-developed {002} faces being formed. This results from significantly decreased growth rates in 〈002〉 relative to 〈200〉. Crystallographic considerations suggest that PHOX selectively adsorbs and inhibits growth of the {002} faces. This is the result of binding between amino groups protruding from the {002} surface of the 6-APA crystals and the carboxylic acid groups which are common to both the 6-APA and the PHOX molecules. PHOX thus acts as a tailor-made additive which is present in the solution as a result of the original 6-APA synthesis step.

Precipitation kinetics of barium sulphate were determined from a series of batch experiments. The thermodynamic supersaturation ratios were calculated from conductivity measurements while the crystal size distributions were measured by means of an electrical zone sensing particle size analyser. Using the measured crystal size distributions the nucleation and growth rates were determined by the moments method. Observed nucleation rates were strongly affected by the thermodynamic supersaturation ratio as well as by the stirrer speed and magma density and indicated the occurrence of both primary and secondary nucleation. The nucleation kinetics were therefore expressed as a combination of primary and secondary nucleation terms. The dependence of the growth rates on the thermodynamic supersaturation ratio and the stirrer speed suggested that both the diffusion and surface integration processes influenced the kinetics.

The influence of the structurally similar additives, o-chloronitrobenzene (o-CNB), p-chloronitrobenzene (p-CNB),p-dichlorobenzene (p-DCB), and p-dinitrobenzene (p-DNB), on the morphology of m-chloronitrobenzene (m-CNB) crystals has been investigated theoretically and experimentally. Both experiments and predictions confirmed the strong polar morphology of m-CNB crystals grown in the presence of the additives p-CNB and p-DNB. Calculations indicate strong binding interactions of these molecules with crystal surfaces at one end of the polar (001) growth direction. Experiments confirm this through the observed rounding and development of polar morphology along the c-axis

The solubilities of tetracosane (n-C[sub 24]H[sub 50]) in heptane (n-C[sub 7]H[sub 16]), dodecane (n-C[sub 12]H[sub 26]), a mixture of isomers of decahydronaphthalene (C[sub 10]H[sub 18]), and m and p-xylene (C[sub 8]H[sub 10]) have been determined over the temperature range 279.3--305.8 K. These solvents were chosen as being representative of the types of molecules present in fuel oils. The results are well described by the equation ln x[sub 2] = [minus]([Delta]H[sup d]/RT) + ([Delta]S[sup d]/R) for which the parameters [Delta]H[sup d] and [Delta]S[sup d] are given. The liquid-phase activity coefficients for the solid at 293.2 K have been derived from the measured solubilities and compared with values calculated from the Scatchard-Hildebrand equation and the UNIFAC group contribution method. Relatively good agreement is obtained using the Scatchard-Hildebrand equation, especially in the case of normal hydrocarbon solvents.

The contributions of mass transfer, surface integration and heat transfer to the overall crystal growth process were investigated for growth of single crystals and crystals in rotating discs under a variety of conditions. Quantitative evaluation was carried out in terms of the non-isothermal effectiveness factor for the surface integration step. Most of the systems, including aqueous solutions of inorganic salts and organic melts, were found to exhibit considerable effects of both mass and heat transfer during crystal growth. It was confirmed that a general criterion for the existence of a significant heat transfer limitation was that the dimensionless parameter β d should be greater than 0.01.

A reproducible method has been developed for studying calcium oxalate crystallization from fresh, minimally diluted (92%) urine with the mixed suspension mixed product removal continuous crystallization technique. All samples were adjusted to give the same starting calcium and oxalate concentrations. Twenty-one recurrent male stone formers were compared with twenty-two healthy controls. There was no difference in crystal growth rates but crystal nucleation rates were much higher in the control group (p = 0.003). Using growth rate and nucleation rate results, the amount of crystalline material in suspension was shown to be lower in the urine from stone formers, and therefore the equilibrium supersaturation in the crystallizer was lower in the control group (p = 0.001). We propose that the ability of a healthy person’s urine to maintain a lower supersaturation is a crucial protective factor distinguishing non-stone formers from stone formers.

A study of the behaviour of particles in dilute liquid suspensions in the proximity of a gas-liquid interface has been carried out. The experiments were performed in a thin channel, the liquid was allowed to evaporate so that a meniscus between the suspension and the vapour was formed. As this receded into the liquid, particles were concentrated in a close-packed band adjacent to the meniscus. As the number of particles in this band increased, the meniscus became unstable and bifurcated. This resulted in the particles from the band being depositied in complex patterns, the development of which was shown to be a strong function of the particle size. Where the meniscus bifurcated, a thin filament of suspension was formed. When the particles in the original suspension were small, mean diameter d ⩽ 10 μm, the liquid subsequently evaporated from the filament to produce a final deposit of particles as ordered chains. In experiments with larger partices d ⩾ 13 μm, the filaments ruptured leave “islands”. As the liquid evaporated from these, particles reassembled under the action of capillary forces to form compact discs. Using spherical particles, precipitates of copper oxalate or glass ballotini, the particles in the discs assumed a structure close to that of the lowest configurational entropy. Various parameters were studied in relation to the above-described particle ordering phenomenon. Particle distribution, concentration and morphology, surface free energy, surface tension and the presence of various types of surface-active agents were all studied. In systems where the deposit formed ordered chains, successive bifurcations of the meniscus produced branched structures, the patterns of which were shown to be reproducible. These patterns resembled river drainage nets and other similar phenomena. The analysis of the patterns showed them to be fractal structrues with a fraction dimension of 1.31.

Precipitation of silica achieved by neutralization of dilute sodium silicate solution with dilute sulphuric acid in a 751 pilot-scale agitated vessel with two impellers was used to investigate both crystallization and agglomeration kinetics from the measured transient crystal volume distributions. The overall neutralization process was represented by a homogeneous chemical reaction followed by precipitation and resulting in an agglomerated silica precipitate. It was carried out in three stages involving a discontinuous semi-batch operation, primary neutralization, ageing and secondary neutralization being the three stages involved. The method of moments analysis in crystal volume coordinates was used to deduce the kinetics rates. All the kinetic rates obtained from the measured crystal volume distributions were correlated by empirical kinetic expressions in terms of observables . The calculated time variations of solution silica concentration, total crystal number and population average crystal volume from the process simulation using the derived kinetic correlations compared favourably with experimentally observed values.

This paper describes an experimental study of residence time distribution (RTD) by pulse response analysis in a continuous Couette flow device with rotating inner cylinder and stationary outer cylinder. The experiments were performed under conditions of (a) negligible and (b) significant influence of molecular diffusion and (c) Taylor vortex flow. Diethylene glycol and water were used as the test fluids with congo red dye and potassium permanganate solution as tracers respectively. A unique RTD described by an analytical expression was observed for experiments with low axial Reynolds number under the condition of negligible influence of molecular diffusion. For most experiments performed under conditions of significant influence of molecular diffusion and Taylor vortex flow regime over the ranges 0

The development of a concentration gradient along the vertical axis of a column of quiescent solution is explained within the framework of nonequilibrium thermodynamics. The formulae derived enabled us to determine explicitly the concentration difference between two vertical levels in a liquid column and specific conditions under which the concentration profile is at equilibrium. The concept of solute cluster formation in a supersaturated solution is consistent with the presented theory although the theory itself does not provide any direct or indirect proof of the occurrence of clustering.

The precipitation of a solid from a solution generally involves several steps,viz., the purification of the solution, reaction and precipitation, separation, drying, comminution and classification of the solid. In this work, we consider the precipitation of a salt, copper oxalate, for which we have developed a process whereby separation of a desired cation, Cu2+ from a solution takes place by selective mass transfer through a membrane film. A chemical reaction and precipitation in a confined environment is carried out so that the resulting particle size of the precipitate can be controlled within the range 0.1–7,μm and particularly from 0.1–2.0 μm. The process, based on extraction using a liquid surfactant membrane with precipitation of the solid in the internal phase of the emulsion membrane, effectively eliminates the need for solution pretreatment to remove competing ions and most importantly will eliminate the need for further size modification of the precipitate.

The effect of heat transfer and the role of the surface integration process in crystal growth are analysed quantitatively in terms of a non-isothermal effectiveness factor, defined as the ratio of actual growth rate to the rate that would be obtained if conditions of the supercooled or supersaturated bulk liquid existed at the crystal surface. The expression for simulataneous transfer of mass and heat in the liquid phase in the vicinity of the growing crystal surface is developed. Surface conditions of growing crystals, freely settling in a supercooled or supersaturated liquid, are determined for seven binary systems including organic melts and aqueous solutions of inorganic salts. Organic melt systems and some aqueous systems exhibit effectivenss factors significantly less than unity, indicating that the liquid phase transport phenomena play an important role in crystal growth. As a measure of the contribution of heat transfer, the inorganic systems this ratio increases at high concentrations of the crystallizing component and high heats of crystallization. An empirical criterior for the importance of thermal processes is that the non-dimensional group βd ≡ (k′ ϱfΔH/h′)(dz*A/dT) should be greater than 0.01.

Growth rate data of surface-integration controlled growing potassium sulphate crystals in the size range. 10–100μm are presented. The experiments were carried out in an agitated vessel crystallizer. The crystal growth rates were calculated from the shift of the population distributions with time as measured by a Coulter-Counter. In particular the effect of different surface qualities on the growth rates was investigated and clearly demonstrated. The existence of a growth rate dispersion (GRD) was shown for crystals in an agitated crystallizer. This is a new observation since previously this effect was only investigated for stagnant solutions in the case of the above mentioned range of crystal sizes.

gamma-carboxyglutamic acid (GLA) is an amino acid with a high affinity for calcium. It is found in urine both as the free amino acid and incorporated into proteins such as osteocalcin. Free and bound GLA have been reported to be found at higher concentrations in the urine of stone formers than controls. We have investigated the effect of GLA and calcium, at physiological levels, on the crystallisation of calcium oxalate using a mixed suspension mixed product removal continuous crystalliser. GLA caused very significant changes in the crystallisation kinetics, but the effect was dependent on the calcium concentration. At 4 mM calcium, GLA decreased the growth rate and increased the nucleation rate; at 12 mM the reverse occurred. At all concentrations of calcium tested, GLA caused a significantly increased crystal mass to be produced. Our evidence supports the hypothesis that GLA modifies calcium oxalate crystallisation and could be a promoter of stone formation in vivo, particularly at moderately elevated levels of calcium excretion.

The morphology of m-chloronitrobenzene (mCNB) crystals grown from pure and binary melts with its ortho and para isomers was observed. By increasing the isomer concentration the morphology was found to change from prismatic to plate-like to needle-like for the mCNB-oCNB system. For the mCNB-pCNB system lenticular crystals, changing in shape to petal-like through a paper-knife appearance, in which one end of the crystal is rounded and the other facetted, were observed. The cause of these changes is discussed and attributed to probable occupation of specific sites on the growing surface by isomer molecules.

Fractional crystallization provides a convenient means of purifying materials at low energy requirements and can be carried out continuously in a column crystallizer. This paper is concerned with the development of a model to describe the crystal forming cooling section of a column crystallizer used to separate a simple eutectic system. Experimentally determined crystal size distributions at various sections of the column obtained at different product to feed ratios are used to characterize the two parameters of a phenomenological model based on a dispersed plug flow configuration. The effects of hydrodynamic conditions on the model parameters are assessed in terms of dimensionless groups.

On presente les caracteristiques et les avantages d'un «mini» cristalliseur ayant une capacite d'environ 20 ml

The final phase in the design of the supply-chain and manufacturing systems is to implement the factory reorganization. Once the authority to proceed has been obtained and all the detailed preparation work completed, implementation of factory reorganization should be done in as short a time as possible, minimizing disruption to customer deliveries. The project management and sequenced planning of events throughout the reorganization has a significant impact upon the overall time taken to complete the moves. The aim should be to systematically move all the equipment associated with a particular cell, progressively handing it back to production, focusing on the bottleneck processes that cannot be replicated on site or at subcontractors. It is impossible for the project team to have designed an optimum manufacturing process, due to the sheer complexity of the task and the number of variables that are taken into account. The initial design now requires the implementation team and module/cell team members to work together to refine the process, introducing a continual improvement process aimed at manufacturing consistently good quality products, on time and eliminating waste from all aspects of the process. The continuous improvement approach must be rigorously promoted by senior managers to transform the supply-chain and manufacturing system design into a world class process.

This chapter explains an important step of manufacturing system collating the critical aspects of the company business plan, market requirements, product, and manufacturing information and develops a module and cell structure for the supply-chain and internal manufacturing systems. Defining the manufacturing modules and cells is one of the most critical aspects of the manufacturing system design process, as it determines the structure of operations, deployment of resources, utilization of facilities, and level of vertical integration. The module and cell definition process is accomplished in three stages. The first stage is to identify natural groups or product families embodied within the range of products and components. The method for selecting groups is dependent upon the type of business operation and cannot be prescriptive. The most powerful technique for identifying families is Pareto analysis, which can be used for deciding the important factors to be given greatest priority. The second stage of the module and cell definition process is for the operations management team preparing a written manufacturing strategy. The third stage is to rate operational performance against good practice checklists developed to identify current best practice within a particular business sector.

The dynamic design stage follows steady state design attempting to predict more accurately the behavior of a system under typical operating conditions. The dynamic analysis tests the validity of assumptions of steady state design and determines the likely impact of unplanned events. The objective of this phase is to allow the actual production capacity to be predicted, compared to the forecast requirements, and cell specification. Any shortfall must be identified and recommendations are made on how to modify the steady state design and introduce control procedures to achieve the desired output levels under a variety of operating conditions. A useful technique for enhancing the robustness of a supply-chain and a manufacturing system's dynamic design is the process failure mode and effects analysis. This is an analytical method developed by the automotive and aerospace industries for evaluating the possible failure modes of products. This technique has been extended to identify possible failure modes in supply-chain and manufacturing processes, determining the impact they could have upon customer service.

Manufacturing businesses must invest time and resources into designing how supply-chain and associated in-house manufacturing systems should operate. The need to design supply-chain and manufacturing systems may be triggered by several events, such as introduction of new product lines, relocation of factories, reduction of operational costs to match competition, installation of new production technology, and launch of additional product lines into existing factories. An outline process for designing supply-chain and manufacturing would include identification of the need for change, identification of module/cell, steady state design, dynamic design, financial justification and implementation, and continual improvement. The supply-chain and manufacturing systems design process can be divided into a number of phases. The first task is to confirm business targets and objectives that encapsulate management direction and meet business aspirations. The next phase is to structure more detailed marketing and product strategies with the specific aim of determining the current and future supply-chain requirements. Another stage is to review product manufacturing, supply-chain, quality and production information that must be compiled to support the manufacturing systems design process.

This chapter deals with designing of manufacturing modules for modular factories. The fundamental concept of modular factories is to bring resources together in natural groups forming cells that are responsible for a product or process. Several cells are grouped together to form a product module. When designing the system it is not always possible to make cells completely self-contained. The steady state design of the cells is based upon events remaining constant with respect to time. Average figures are used for cycle times, changeover times, demand, volumes, product mix, and machine breakdown. This approach simplifies calculations and allows the scope of the different parameters to be determined, but an assumption that factors remain static is over simplistic and proposals must be dynamically analyzed before any recommended solutions are accepted for implementation. The purpose of steady state design is to identify and collate information on the bottleneck processes; compare new manufacturing concepts; evaluate alternative production technologies; introduce lean manufacturing principles; identify the indirect support activities; establish standard working practices; and confirm and quantify the resources needed for operating the cells.

Industrial distribution is critical to many businesses because it is the way products are sold across national and international territories. Companies have to develop a number of routes to market, but for commodity-type products having a local presence is a prime factor in securing sales. These distribution outlets can be owned directly by the manufacturing company, or by a third party with expertise in selling a range of products into local markets. In some instances sales are obtained by waiting for customers to identify a supplier, making purchases similar to a local shop. However, for most industrial products, a more structured method for targeting potential customers has to developed if the business is to achieve its commercial goals.

The process for identifying customer needs and winning orders is probably the least well-defined business process. It also has the widest spectrum of techniques for accomplishing the task. The process described in this section is based upon a high-technology manufacturing company seeking to move up the supply chain, providing products and services with a higher value-added content. It aims to outline an effective set of procedures ensuring the finite resources available to secure new business are targeted at the best opportunities in the marketplace to meet the strategic objectives of the business.

The four fundamental business processes need some staff support operating across the different business areas, directing and integrating activities. One of these roles is customer satisfaction and quality; it is a role not widely employed by companies, but provides the remit for ensuring that regular customer contact is maintained at senior management level. It seeks to understand the customer’s perception of how the company is performing as a supplier. It also has the authority within the business to instigate any corrective actions needed to resolve customer problems and has responsibility for ensuring the necessary quality systems are fully-developed and relentlessly followed by everybody associated with providing products and services. This is an extremely broad role, normally assigned the responsibility of an experienced senior manager with a small team providing expertise to initiate and drive projects. The resources needed for implementation remain within the core business processes, to prevent establishing bureaucratic systems that would remove ownership from the managers responsible for delivering the operational objectives.

The company business plan is the most important document a management team prepares because it sets the future direction and financial commitments for the plan period (usually three or five years). Business plans have traditionally been prepared from a collection of departmental plans and collated into one overall plan. This approach suffers from the same deficiencies found in functional organisations, and therefore a business must instigate a business planning process around the fundamental processes which drive it.

Businesses have been traditionally structured around functional organisations that evolved from the principles promoted by Adam Smith two hundred years ago. His concepts were based upon dividing the manufacturing process into a number of simple tasks, and these principles became entrenched in our Western manufacturing practices.

Mixed suspension, mixed product removal (MSMPR) continuous crystallisation has been applied in many studies of calcium oxalate crystallisation. It is particularly appropriate for urolithiasis research, as Finlayson has shown that crystallisation within the urinary tract can be modelled effectively by a series of MSMPR continuous crystallisers1. The MSMPR method gives a better representation of the renal environment than others because it reaches a steady state with a constant supersaturation and operates with continuous flow. As a result, individual crystals only remain in the suspension for a relatively short time, not much different from transit times through the kidney. Another advantage of the MSMPR technique is that nucleation and growth rates can be measured simultaneously, but independently, in units of no/min/mL and μm/min.