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Background Prior evidence indicates that negative symptom severity and cognitive deficits, in people with schizophrenia (PSZ), relate to measures of reward-seeking and loss-avoidance behavior (implicating the ventral striatum/VS), as well as uncertainty-driven exploration (reliant on rostrolateral prefrontal cortex/rlPFC). While neural correlates of reward-seeking and loss-avoidance have been examined in PSZ, neural correlates of uncertainty-driven exploration have not. Understanding neural correlates of uncertainty-driven exploration is an important next step that could reveal insights to how this mechanism of cognitive and negative symptoms manifest at a neural level. Methods We acquired fMRI data from 29 PSZ and 36 controls performing the Temporal Utility Integration decision-making task. Computational analyses estimated parameters corresponding to learning rates for both positive and negative reward prediction errors (RPEs) and the degree to which participates relied on representations of relative uncertainty. Trial-wise estimates of expected value, certainty, and RPEs were generated to model fMRI data. Results Behaviorally, PSZ demonstrated reduced reward-seeking behavior compared to controls, and negative symptoms were positively correlated with loss-avoidance behavior. This finding of a bias toward loss avoidance learning in PSZ is consistent with previous work. Surprisingly, neither behavioral measures of exploration nor neural correlates of uncertainty in the rlPFC differed significantly between groups. However, we showed that trial-wise estimates of relative uncertainty in the rlPFC distinguished participants who engaged in exploratory behavior from those who did not. rlPFC activation was positively associated with intellectual function. Conclusions These results further elucidate the nature of reinforcement learning and decision-making in PSZ and healthy volunteers.

Rooted in a trans-territorial framework, the present study was designed to provide new evidence regarding the patterns of communication among Hurricane Maria survivors who migrated to the U.S. in the aftermath of the storm.A total of 319 Hurricane Maria survivor adults ages 18 and older were recruited into the Adelante Boricua study between August 2020 and October 2021. Most participants had relocated to the U.S. between 2017 and 2018. We used latent profile analysis and multinomial regression to examine the relationship of technology-based communication with depressive symptoms, well-being, cultural connection, and migration stress.We identified a five-class solution, consisting of (1) moderate communication (32%), (2) disengaged (24%), (3) no social media (18%), (4) daily with family in Puerto Rico (6%), and (5) daily trans-territorial (13%) typologies. Participants in the disengaged class were more likely to report elevated depressive symptoms and limited English proficiency, lower prosocial behaviors, lower levels of religiosity, lower attendance at religious services in the U.S., and less engagement in social activities, compared to participants in the Moderate Communication class.Roughly one in four individuals in our sample reported very limited technology-based communication with friends/family in their sending and new-receiving communities. As technology and smartphones continue to become integrated into 21st-century life, it is vital that researchers explore how the tremendous potential for connectedness relates to trans-territorial crisis migrants' well-being and adaptation.

Industry-standard quality management systems such as Six Sigma and emerging Industry 4.0 compliant production processes demonstrate the importance of in-line condition monitoring of manufacturing methods for achieving the highest levels of product quality. Measurement data collected as the process is running can inform the operator about unexpected changes in machine operation or raw materials that could negatively impact production; and offer an opportunity for a process control intervention to stabilise production. However, micro-manufacturing production lines can pose a challenging environment for deploying such systems, since processing events can occur extremely rapidly and in harsh environments. Moreover, the small scale of micro-nano featured components can make sensor installation even more problematic. Recently, ultrasonic micromoulding has drawn attention in niche markets due to its unique advantages for processing thermoplastics as a new micro-manufacturing technology. The process differs from conventional moulding significantly by eliminating the need for a plasticising screw and using direct application of ultrasonic energy to melt the polymer. This offers numerous benefits such as decrease in energy usage, moulding at lower pressures, easier cleaning, and reduced material residence times, the latter which could be beneficial for pharma-grade polymers or polymers with active ingredients. However, very little work has been reported attempting to monitor the process using in-line measurements. This work aims to evaluate the characteristics of the ultrasonic micromoulding process for microinjection moulding of a microneedle array using a range of sensor technologies including: data recorded by the machine controller; a high-speed thermal camera and a cavity pressure transducer. The data has captured the highly dynamic process environment with a high degree of accuracy. The relationship between the process data and dimensional quality of the ultrasonically micromoulded products has been quantified and subsequently implemented as a cost-effective in-line quality assurance method.

A green approach has been used for co-crystallization of noncongruent co-crystal pair of caffeine/maleic acid using water. Ultrasound is known to affect crystallization; hence, the effect of high power ultrasound on the ternary phase diagram has been investigated in detail using a slurry co-crystallization approach. A systematic investigation was performed to understand how the accelerated conditions during ultrasound-assisted co-crystallization will affect different regions of the ternary phase diagram. Application of ultrasound showed considerable effect on the ternary phase diagram, principally on caffeine/maleic acid 2:1 (disappeared) and 1:1 co-crystal (narrowed) regions. Also, the stability regions for pure caffeine and maleic acid in water were narrowed in the presence of ultrasound, expanding the solution region. The observed effect of ultrasound on the phase diagram was correlated with solubility of caffeine and maleic acid and stability of co-crystal forms in water.

The use of near infra red spectroscopy to predict the concentration of two pharmaceutical co-crystals; 1:1 ibuprofen–nicotinamide (IBU-NIC) and 1:1 carbamazepine–nicotinamide (CBZ-NIC) has been evaluated. A partial least squares (PLS) regression model was developed for both co-crystal pairs using sets of standard samples to create calibration and validation data sets with which to build and validate the models. Parameters such as the root mean square error of calibration (RMSEC), root mean square error of prediction (RMSEP) and correlation coefficient were used to assess the accuracy and linearity of the models. Accurate PLS regression models were created for both co-crystal pairs which can be used to predict the co-crystal concentration in a powder mixture of the co-crystal and the active pharmaceutical ingredient (API). The IBU-NIC model had smaller errors than the CBZ-NIC model, possibly due to the complex CBZ-NIC spectra which could reflect the different arrangement of hydrogen bonding associated with the co-crystal compared to the IBU-NIC co-crystal. These results suggest that NIR spectroscopy can be used as a PAT tool during a variety of pharmaceutical co-crystal manufacturing methods and the presented data will facilitate future offline and in-line NIR studies involving pharmaceutical co-crystals.

highlights � This paper discusses the energy conservation of an extruder. � This describes the energy and thermal efficiencies in polymer extrusion. � This explores the correlation between energy demand and thermal stability. � This explores radial temperature fluctuations of the melt flow in extrusion. � This models the total power demand in polymer extrusion empirically. abstract Thermal stability is of major importance in polymer extrusion, where product quality is dependent upon the level of melt homogeneity achieved by the extruder screw. Extrusion is an energy intensive process and optimisation of process energy usage while maintaining melt stability is necessary in order to pro- duce good quality product at low unit cost. Optimisation of process energy usage is timely as world energy prices have increased rapidly over the last few years. In the first part of this study, a general dis- cussion was made on the efficiency of an extruder. Then, an attempt was made to explore correlations between melt thermal stability and energy demand in polymer extrusion under different process settings and screw geometries. A commodity grade of polystyrene was extruded using a highly instrumented sin- gle screw extruder, equipped with energy consumption and melt temperature field measurement. More- over, the melt viscosity of the experimental material was observed by using an off-line rheometer. Results showed that specific energy demand of the extruder (i.e. energy for processing of unit mass of polymer) decreased with increasing throughput whilst fluctuation in energy demand also reduced. How- ever, the relationship between melt temperature and extruder throughput was found to be complex, with temperature varying with radial position across the melt flow. Moreover, the melt thermal stability dete- riorated as throughput was increased, meaning that a greater efficiency was achieved at the detriment of melt consistency. Extruder screw design also had a significant effect on the relationship between energy consumption and melt consistency. Overall, the relationship between the process energy demand and thermal stability seemed to be negatively correlated and also it was shown to be highly complex in nat- ure. Moreover, the level of process understanding achieved here can help to inform selection of equip- ment and setting of operating conditions to optimise both energy and thermal efficiencies in parallel. 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://

In this work, a highly instrumented single screw extruder has been used to study the effect of polymer rheology on the thermal efficiency of the extrusion process. Three different molecular weight grades of high density polyethylene (HDPE) were extruded at a range of conditions. Three geometries of extruder screws were used at several set temperatures and screw rotation speeds. The extruder was equipped with real-time quantification of energy consumption; thermal dynamics of the process were examined using thermocouple grid sensors at the entrance to the die. Results showed that polymer rheology had a significant effect on process energy consumption and thermal homogeneity of the melt. Highest specific energy consumption and poorest homogeneity was observed for the highest viscosity grade of HDPE. Extruder screw geometry, set extrusion temperature and screw rotation speed were also found to have a direct effect on energy consumption and melt consistency. In particular, specific energy consumption was lower using a barrier flighted screw compared to single flighted screws at the same set conditions. These results highlight the complex nature of extrusion thermal dynamics and provide evidence that rheological properties of the polymer can significantly influence the thermal efficiency of the process.

An infrared temperature sensor has been used to provide real time quantification of the thermal homogeneity of polymer extrusion. The non-intrusive sensor was located in the barrel of a single screw extruder, positioned such that it provided a measurement of melt temperature in the channel of the metering section of the extruder screw. The rapid response of the technique enabled melt temperature within the extruder screw channel to be monitored in real time, allowing quantification of the thermal stability of the extrusion process. Two polyethylenes were used in experiments with three extruder screw geometries at a range of screw speeds. Data generated by the infrared sensor was found to be highly sensitive to thermal fluctuations relating to the melting performance of the extruder screw. Comparisons made with an intrusive thermocouple grid sensor located in the extruder die suggested that the infrared technique was able to provide a similar level of information without disturbing the process flow. This application on infrared thermometry could prove highly useful for industrial extrusion process monitoring and optimization. POLYM. ENG. SCI., 55:1059–1066, 2015. © 2014 The Authors. Polymer Engineering & Science published by Wiley Periodicals, Inc. on behalf of Society of Plastics Engineers

Polymer extrusion, in which a polymer is melted and conveyed to a mould or die, forms the basis of most polymer processing techniques. Extruders frequently run at non-optimised conditions and can account for 15–20% of overall process energy losses. In times of increasing energy efficiency such losses are a major concern for the industry. Product quality, which depends on the homogeneity and stability of the melt flow which in turn depends on melt temperature and screw speed, is also an issue of concern of processors. Gear pumps can be used to improve the stability of the production line, but the cost is usually high. Likewise it is possible to introduce energy meters but they also add to the capital cost of the machine. Advanced control incorporating soft sensing capabilities offers opportunities to this industry to improve both quality and energy efficiency. Due to strong correlations between the critical variables, such as the melt temperature and melt pressure, traditional decentralized PID (Proportional–Integral–Derivative) control is incapable of handling such processes if stricter product specifications are imposed or the material is changed from one batch to another. In this paper, new real-time energy monitoring methods have been introduced without the need to install power meters or develop data-driven models. The effects of process settings on energy efficiency and melt quality are then studied based on developed monitoring methods. Process variables include barrel heating temperature, water cooling temperature, and screw speed. Finally, a fuzzy logic controller is developed for a single screw extruder to achieve high melt quality. The resultant performance of the developed controller has shown it to be a satisfactory alternative to the expensive gear pump. Energy efficiency of the extruder can further be achieved by optimising the temperature settings. Experimental results from open-loop control and fuzzy control on a Killion 25 mm single screw extruder are presented to confirm the efficacy of the proposed approach.

Polymer extrusion is regarded as an energy-intensive production process, and the real-time monitoring of both energy consumption and melt quality has become necessary to meet new carbon regulations and survive in the highly competitive plastics market. The use of a power meter is a simple and easy way to monitor energy, but the cost can sometimes be high. On the other hand, viscosity is regarded as one of the key indicators of melt quality in the polymer extrusion process. Unfortunately, viscosity cannot be measured directly using current sensory technology. The employment of on-line, in-line or off-line rheometers is sometimes useful, but these instruments either involve signal delay or cause flow restrictions to the extrusion process, which is obviously not suitable for real-time monitoring and control in practice. In this paper, simple and accurate real-time energy monitoring methods are developed. This is achieved by looking inside the controller, and using control variables to calculate the power consumption. For viscosity monitoring, a ‘soft-sensor’ approach based on an RBF neural network model is developed. The model is obtained through a two-stage selection and differential evolution, enabling compact and accurate solutions for viscosity monitoring. The proposed monitoring methods were tested and validated on a Killion KTS-100 extruder, and the experimental results show high accuracy compared with traditional monitoring approaches.

Polymer extrusion is an energy intensive process, which is often run at less than optimal conditions. The extrusion process consists of gradual melting of solid polymer by thermal conduction and viscous shearing between a rotating screw and a barrel; as such it is highly dependent upon the frictional, thermal and rheological properties of the polymer. Extruder screw geometry and extrusion variables should ideally be tailored to suit the properties of individual polymers, but in practice this is rarely achieved due to the lack of understanding of the process. Here, in-process monitoring techniques have been used to characterise the thermal dynamics of the extrusion process. Novel thermocouple grid sensors have been used to measure melt temperature fields within flowing polymer melts at the entrance to an extruder die in conjunction with infra-red thermometers and real-time quantification of energy consumption. A commercial grade of polyethylene has been examined using three extruder screw geometries at different extrusion operating conditions to understand the process efficiency. Extruder screw geometry, screw rotation speed and set temperature were found to have a significant effect on the thermal homogeneity of the melt and process energy consumed.

Polymer extrusion is an energy intensive production process andprocess energy efficiency has become a key concern in the currentindustry with the pressure of reducing the global carbonfootprint. Here, knowledge of the pattern of energy usage andlosses of each component in the plant is highly useful in theprocess energy optimization. Moreover, it is essential to maintainthe melt quality while improving the energy efficiency in polymerprocessing. In this work, an investigation was made on the totalenergy consumption, drive motor energy consumption, power factorand the melt temperature profile across the die melt flow (as anindication of the melt thermal quality) of an industrial scaleextruder with three different screw geometries, three polymertypes and wide range of processing conditions (altogether 135different processing situations were observed). This aims to widenthe knowledge on process energy and thermal behaviors whileexploring possible correlation/s between energy demand and meltquality (in terms of melt temperature fluctuations across the meltflow). The results showed that the level and fluctuations of theextruder's power factor is particularly dependent upon thematerial being processed. Moreover, it seems that there is arelation between the level of energy demand of the heaters and thelevel of melt temperature fluctuations. While the extruderspecific energy consumption decreases with increasing screw speed,specific energy consumption of the drive motor may have eitherincreasing or decreasing behavior. Overall, this study providesnew insights in a wide range on process energy demand and meltthermal quality in polymer extrusion. Moreover, further researchis recommended to establish strong correlation/s between processenergy consumption and melt thermal quality which should help toenhance process control and hence the product quality in singlescrew polymer extrusion.

Cache coherent interconnects in modern SoC designs represent a complex design verification challenge. Coherence protocols trigger complex interactions between the heterogeneous mixes of caches and other system masters that comprise these SoCs. Furthermore, most coherence bugs are very sensitive to the exact timing and sequence of operations, and hence are difficult to target. Traditional DV only covers a limited portion of the state-space before the device tapeout. Red Baron is a SoC system level cache coherence stress tester which automatically generates testcases on the fly, taking into account the behavior of the CPU's cache, IO coherence, system memory and interconnect. This auto-generation methodology allows it to scale through the entire SoC design phases, from RTL simulation, emulation to silicon. This paper presents Red Baron's design, implementation and accomplishments on TI multicore SoCs.

Melt temperature is one of the key variables in polymer extrusion which determines process thermal stability and hence melt quality. Therefore, melt temperature is commonly measured in polymer processing and point/bulk melt temperature measurement methods are widely used in the present industry. Some thermal profile measurement methods have also been attempted in research. This study presents a review of melt temperature measurements in polymer extrusion in research and industry, and describes the results of an experimental evaluation carried out to explore the performance of five melt temperature measurement techniques. In addition, an investigation was carried out on the fully developed melt temperature profile of a cylindrical rod die. Moreover, the existing challenges and possible future applications for extrusion thermal monitoring are discussed. The results confirmed that melt temperature varied significantly at different radial locations within the die. Point/bulk melt temperature measurements were found to provide relatively limited information on process thermal quality close to the die wall. Hence, information provided by these sensors is less representative of actual thermal conditions as they are unable to capture thermal information from the whole melt flow cross-section. Therefore, the importance of the development of industrially compatible thermal profile measurement techniques is emphasised.

Thermocouple grids have been shown to provide a unique insight into melt temperature fields and their time dependent behaviour in extruders. These systems have been extended from single axis designs to larger arrays for more detailed temperature measurements. Nine junction (3 × 3) arrays have provided a map of the temperature profile across the melt, and the technique has been used to assess the effect of extrusion conditions such as polymer type, screw geometry and melt pressure. The data are proving invaluable for extruder screw design and to inform more accurate computer modelling of polymer melt flows. Single axis grids have also been applied to twin screw compounding extrusion, and the results showed a significant amount of shear heating with the hottest points being along the centre line of the two screws.

An idealised model of core-out in water assisted injection moulding (WAIM) is set up to isolate the effect of cooling by the water on the deposited layer thickness. Based on simulations, this is investigated for a specific case as a function of Pearson number and power law index. It is found that cooling significantly reduces the layer thickness to the extent that a change in the flow regime ahead of the bubble, from bypass to recirculating flow, is possible. For shear thinning melts with high temperature coefficient of viscosity, the simulations show very low layer thickness, which may indicate unfavourable conditions for WAIM. Although in the real moulding situation, other effects will be superimposed on those found here, the results provide new insights into the fundamentals of WAIM. Investigation of other effects characterised by Fourier and Reynolds numbers will be reported subsequently. Some early process measurement results from an experimental WAIM mould are presented. Reductions in residu...

Process imaging of micromoulding cavity flows has been performed using a transparent mould and high speed camera system creating a powerful method of studying the flow behaviour, shrinkage and internal stresses of polymeric materials during the micromoulding process. Results of these measurements will be presented with discussion of how they may be exploited to further understand crucial process parameters and physical models. An inline optical inspection technique currently under development is described in detail, along with initial results. This system offers 100% product inspection in three dimensions for microscale features.

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Real-time diagnostics of ceramic powder injection molding using a commercial micromolding machine was performed using ultrasound. Miniature ultrasonic sensors were integrated onto the mold...

An ultrasound sensor system has been applied to the mould of both the water and gas assisted injection moulding processes. The mould has a cavity wall mounted pressure sensor and instrumentation to monitor the injection moulding machine. Two ultrasound sensors are used to monitor the arrival of the fluid (gas or water) bubble tip through the detection of reflected ultrasound energy from the fluid polymer boundary and the fluid bubble tip velocity through the polymer melt is estimated. The polymer contact with the cavity wall is observed through the reflected ultrasound energy from that boundary. A theoretically based estimation of the residual wall thickness is made using the ultrasound reflection from the fluid (gas or water) polymer boundary while the samples are still inside the mould and a good correlation with a physical measurement is observed.

Ultrasonic technology provides a powerful and noninvasive method of in-process measurement during injection molding and extrusion. Changes in the velocity, attenuation and reflection coefficients of high frequency sound waves can be related to the state and conditions of the materials through which they propagate. The velocity of an ultrasonic wave changes with density and elastic moduli; this allows information on solidification and material properties to be collected during the molding cycle. The time of flight of the wave is a function of velocity and path length. This paper shows that it can be correlated with the residual wall thickness of polymer in the mold during gas assisted injection molding. POLYM. ENG. SCI., 47:1730–1739, 2007. © 2007 Society of Plastics Engineers

Experimental observations of melt temperature profiles and melting performance of extruder screws are reported. A novel temperature sensor consisting of a grid of thermocouple junctions was used to take multiple temperature readings in real time across melt flow in a single screw extruder. Melt pressure in the die and power consumption were also monitored. Three extruder screws at a range of screw speeds were examined for a commercial grade of low density polyethylene. Results showed melt temperature fields at low throughputs to be relatively independent of screw geometry with a flat-shaped temperature profile dominated by conduction. At high throughputs, melting performance and measured temperature fields were highly dependent upon screw geometry. A barrier-flighted screw with Maddock mixer achieved significantly better melting than single flighted screws. Low temperature “shoulder” regions were observed in the temperature profiles of single-flighted screws at high throughput, due to late melting of the solid bed. Stability of the melt flow was also dependent upon screw geometry and the barrier-flighted screw achieving flow with lower variation in melt pressure and temperature. Dimensionless numbers were used to analyze the relative importance of conduction, convection, and viscous shear to the state of the melt at a range of extrusion conditions. Polym. Eng. Sci. 46:1706–1714, 2006. © 2006 Society of Plastics Engineers

Injection moulding techniques have been miniaturised and refined to achieve micromoulding which aims to satisfy the need for mass production of low-cost micro- and nanoscale components. However, the microscale mould cavity features and extreme processing conditions which are inherent in the process can result in larger process variations than conventional injection moulding, with a corresponding increase in the probability of producing an unsatisfactory product. Accurate process diagnosis is required to ensure process reliability but integration of sensors onto the small and highly detailed mould units can be problematic and alternatives may need to be sought. Piezoelectric film ultrasonic transducers were integrated onto the extrusion barrel and mould insert of a micromoulding machine for real-time, non-destructive and non-intrusive process diagnosis with an ultrasonic pulse-echo technique. Polymer degradation owing to excessive heating at the extrusion barrel was successfully probed by measuring the ultrasonic velocities in the polymer at the mould insert. Filling incompleteness of the mould cavity was also sensitively detected by monitoring the ultrasonic energy variation transmitted into the part at different points along the melt flow length. The developed ultrasonic sensors and technique enable optimisation and in-process quality assurance of the moulded parts which ensures that maximum process efficiency can be achieved.

Melt temperature fields have been measured in single screw extrusion using novel thermocouple grid, ultrasound and infrared sensor techniques. The effects of screw and die geometry on the melt temperature profile have been investigated using simple slit and rod dies on a single screw extruder. Comparisons have been made between a general purpose polyolefin screw with gradual melting zone, a rapid transition screw, and a barrier flighted screw with a Maddock mixer. Significant differences in melting and temperature profiles were observed between the three extruder screws. Die geometry of the simple dies studied here was found to have a minor effect on the melt temperature field in regions near the die wall. Die head pressure had a more significant effect on melt temperature distribution.

The cure of polydicyclopentadiene conducted by ring-opening metathesis polymerisation in the presence of a Grubbs catalyst was studied using non-invasive Raman spectroscopy. The spectra of the monomer precursor and polymerised product were fully characterised and all stages of polymerisation monitored. Because of the monomer's high reactivity, the cure process is adaptable to reaction injection moulding and reactive rotational moulding. The viscosity of the dicyclopentadiene undergoes a rapid change at the beginning of the polymerisation process and it is critical that the induction time of the viscosity increase is determined and controlled for successful manufacturing. The results from this work show non-invasive Raman spectroscopic monitoring to be an effective method for monitoring the degree of cure, paving the way for possible implementation of the technique as a method of real-time analysis for control and optimisation during reactive processing. Agreement is shown between Raman measurements and ultrasonic time of flight data acquired during the initial induction period of the curing process.

Spectroscopic techniques such as Raman, mid-infrared (MIR), and near-infrared (NIR) have become indispensable analytical tools for rapid chemical quality control and process monitoring. This paper presents the application of in-line Fourier transform near-infrared (FT-NIR) spectroscopy, Raman spectroscopy, and ultrasound transit time measurements for in-line monitoring of the composition of a series of high-density polyethylene (HDPE)/polypropylene (PP) blends during single-screw extrusion. Melt composition was determined by employing univariate analysis of the ultrasound transit time data and partial least squares (PLS) multivariate analysis of the data from both spectroscopic techniques. Each analytical technique was determined to be highly sensitive to changes in melt composition, allowing accurate prediction of blend content to within ±1% w/w (1σ) during monitoring under fixed extrusion conditions. FT-NIR was determined to be the most sensitive of the three techniques to changes in melt composition. A four-factor PLS model of the NIR blend spectra allowed determination of melt content with a standard prediction error of ±0.30% w/w (1σ). However, the NIR transmission probes employed for analysis were invasive into the melt stream, whereas the single probes adopted for Raman and ultrasound analysis were noninvasive, making these two techniques more versatile. All three measurement techniques were robust to the high temperatures and pressures experienced during melt extrusion, demonstrating each system's suitability for process monitoring and control.

The development and validation of a sensor for extrusion melt temperature field measurement is described. A grid of opposing thermocouple wires was constructed and held in position by a supporting frame. Wires were joined together at crossing points to form thermocouple junctions, which were computer monitored. The mesh was used to monitor melt temperature fields during single screw extrusion at the die entrance. Design and construction of the mesh is described in addition to experimental optimization of wire diameter and junction forming. Calibration of the sensor and potential measurement errors including shear heating effects are discussed. Initial results from single screw extrusion are presented for a commercial grade of low density polyethylene using five- and seven-junction thermocouple meshes. The dependence of melt temperature profile on screw speed is illustrated. At low screw speeds melt temperature profiles were flat in shape and higher than set wall temperatures. At higher screw speeds the profiles became more pointed in shape. Use of higher resolution sensors exposed more complex temperature profiles with shoulder regions.

The relative effects of changes in temperature, pressure and weight percentage filler on ultrasonic velocity through static samples of magnesium hydroxide filled low density polyethylene (LDPE) melt have been determined for a range of temperatures and pressures. Ultrasonic velocity was found to be most sensitive to change in temperature and least sensitive to change in pressure. Using these data and data obtained during extrusion of unfilled LDPE, the amount of magnesium hydroxide present (weight percentage) in LDPE was determined. Values of weight percentage calculated from extrusion data were compared with values obtained from the thermogravimetric analysis of extrudate. Variations in weight percentage of filler between the two sets of data followed the same trend with time of extrusion.

Ultrasonic techniques are recognised as powerful sources of process information. Transducers are applied directly, are non-invasive, yet interrogate the entire melt cross-section, while data are available real-time. During injection moulding, two zones are considered: nozzle and cavity. In the nozzle, ultrasonic velocity measurement provides temperature and pressure information. Mean temperatures not observed by other techniques are detected. Previous extrusion based experience is used to address issues of high temperature transducer operation. In the cavity, changes in reflection coefficient and ultrasonic velocity provide information on mould filling and part cooling. Various mould geometries are monitored using a number of ultrasonic transducers.

Polymer extrusion is fundamental to the processing of polymeric materials and melt flow temperature homogeneity is a major factor which influences product quality. Undesirable thermal conditions can cause problems such as melt degradation, dimensional instability, weaknesses in mechanical/optical/geometrical properties, and so forth. It has been revealed that melt temperature varies with time and with radial position across the die. However, the majority of polymer processes use only single-point techniques whose thermal measurements are limited to the single point at which they are fixed. Therefore, it is impossible for such techniques to determine thermal homogeneity across the melt flow. In this work, an extensive investigation was carried out into melt flow thermal behavior of the output of a single extruder with different polymers and screw geometries over a wide range of processing conditions. Melt temperature profiles of the process output were observed using a thermocouple mesh placed in the flow and results confirmed that the melt flow thermal behavior is different at different radial positions. The uniformity of temperature across the melt flow deteriorated considerably with increase in screw rotational speed while it was also shown to be dependent on process settings, screw geometry, and material properties. Moreover, it appears that the effects of the material, machine, and process settings on the quantity and quality of the process output are heavily coupled with each other and this may cause the process to be difficult to predict and variable in nature. POLYM. ENG. SCI., 54:2430–2440, 2014. © 2013 Society of Plastics Engineers

Non-invasive ultrasound measurements are not currently widely used, due to limitations in high temperature transducer technology and signal processing. These have been addressed in the ultrasound program in our laboratory, where high frequency sampling using our own high temperature probes is now available. The need for high frequency sampling of the ultrasound signal to resolve measurements of transit time (and amplitude) to the required accuracy requires handling of large amounts of data, and in the case of actual polymer processing such as extrusion, data processing needs to be real time. A computer controlled system for the acquisition of such data is described here, with examples of the sensitivity of the measurements to a range of polymer melt process variables, including polymer composition and fillers, for extrusion and injection moulding processing.

Helicopter and surface-based radiometric measurements of forested sites acquired during the Boreal Ecosystem-Atmosphere Study (BOREAS) were analyzed to assess reflectance variability and to address the relationships of reflectances and vegetation indices (VIs) with overstory leaf area index (LAI). Statistical measures of central tendency and linear regression analysis, including a multivariate regression which introduced the effects of understory reflectance, were used. The sensors were deployed during all three intensive field campaigns (IFCs) of 1994 and consisted of (1) a helicopter-based eight-channel Barnes modular multiband radiometer (MMR) and a ground-based Spectron Engineering SE-590 field spectroradiometer to measure spectral reflectance factors, (2) a ground-based Sun photometer used for atmospheric correction, and (3) a LI-COR LAI-2000 plant canopy analyzer and the tracing radiation and architecture of canopies (TRAC) sensor for retrieval of canopy LAI. Of the eight MMR bands, those most strongly correlated to variations in surface LAI were the second and third middle infrared (IR) (1.57–1.80 μm and 2.08–2.37 μm, respectively) with r2=0.45 in both cases, and the red (0.63–0.68 μm) with r2=0.34. In general, linear regression analyses between the canopy LAI measurements and both the helicopter reflectances and VIs resulted in low r2 values commonly less than 0.3. When stratified by season and species, only among sites that were vegetated by aspen (Populus tremuloides) was a stronger relationship observed. In the aspen stands, LAI displayed a traditional trend that maximizes the utility of the VIs: a negative relationship with red reflectance (r2=0.62) and a positive relationship with the near IR (NIR) of r2 = 0.21. The absence of a positive LAI-NIR reflectance trend degraded the information content of the VIs for the conifers. A multivariate regression confirmed the influence of the understory vegetation on the sparse canopies of the boreal forest and suggested that a more complex model-based approach is necessary to better characterize variations in canopy reflectance. Atmospheric contamination of the radiometric signal by smoke from forest fires may also have contributed to the initial unsatisfactory results.

In-line real time monitoring and measurement of density of manufactured products is very important in various industrial applications, especially during extrusion of polymer melts. In this case measurements must be performed in very complex conditions, for example at high temperature (up to 400°C), high pressure (up to 10 MPa) and high chemical activity of the medium, mechanical impacts. Such extreme conditions limit the number of measurement techniques which can be used. The objective of this work was to develop and investigate an in line ultrasonic density measurement technique of polymer melts.

Superior characteristics of the cold sprayed coating have led to many high-tech applications. Until recently, all these applications were carried out using ‘stationary’ systems only, while some applications such as in-situ repair of aircraft body/engine parts require a portable system. Recently a ‘Portable High Pressure Cold Spray System’ called KINETIKS 2000-2 has been developed. This system is capable of 400 C/20 bars nitrogen/helium jet, and produces dense coatings with clean interfaces of many materials. In order to establish the suitability of this process for producing aluminum alloy coatings for aerospace and other high tech industries, various aluminum alloys (CP-Al, HP-Al, 6061 Al, 7005 Al) coatings were produced over many substrate materials (2024 Al, 7005 Al, 4041 Steel, ZE41A Mg). Coatings were characterized using microstructure, bond strength, bend test, corrosion studies, etc. Microstructural study showed that dense coatings with about 2-4% porosity values were produced with clean and well bonded interfaces. Bond strength of these coatings varied between 20 to 35 MPa, Bend test results showed that the coatings have adequate strengths and could withstand severe strain conditions. Salt fog corrosion studies (ASTM B 117) showed that the coatings impart corrosion resistance to the substrates.

The RNA genome segment order, nucleotide sequence and the putative encoded proteins were determined for infectious salmon anaemia virus (ISAV). Eight segments of genomic viral RNA between 1·0 and 2·4 kb in length were identified. RNA segments 1–6 each had a predicted single open reading frame encoding the P1, PB1, NP, P2, P3 and HA proteins, respectively. Segment 7 encoded the P4/P5 proteins and segment 8 encoded the P6/P7 proteins. Seven virion proteins with molecular masses between 25 and 72 kDa were found by SDS–PAGE analysis. The 72 and 42 kDa proteins were immunoreactive with ISAV antiserum from Atlantic salmon. The molecular mass of the 72 kDa virion protein suggested that it was the NP protein encoded by segment 3. The amino acid sequence was conserved, sharing 96·6% identity with the NP protein of a Scottish ISAV isolate. Comparison of the amino acid sequences obtained by N-terminal analyses and cDNA nucleotide translation revealed that the 42 and 47 kDa proteins were the HA and P3 proteins encoded by segments 6 and 5, respectively. In addition, analysis provided evidence for their protein synthesis initiation sites. Like the HA protein, the signal sequence and potential glycosylation sites of P3 suggested that it was a surface glycoprotein. The predicted amino acid sequence shared 83·1, 84·0 and 99·6% identity to the predicted P3 protein sequences for ISAV isolates from Norway, Scotland and Maine, respectively. These results establish the specificity, migration, number and nucleotide sequence of the eight RNA segments of the ISAV genome.

Over the last decade, the demands for higher through-put in production, process optimisation and quality control in the polymer manufacturing industry has led to the implementation of a wide range of process analytical technologies. Techniques such as near-infrared (NIR) spectroscopy, Raman spectroscopy and ultrasound have become indispensable analytical tools for in-process monitoring allowing a molecular specific understanding of material characteristics, rheology and process trends. This paper reports the combined application of these three analytical techniques for assessment of co-polymer melt composition in-line during single screw extrusion to an accuracy of 0.16 wt%. The work demonstrates monitoring and characterisation of a series of ethylene vinyl acetate (EVA) random co-polymers with varying vinyl acetate (VA) content ranging from 2.0 to 43.1 wt%. The sensitivity of each technique to changes in copolymer composition and its ability to acquire real-time process data has been determined. Robust multivariate calibrations suitable for real-time predictions of VA content during processing have been developed and tested.

X-ray absorption spectroscopy (XAS) is a useful tool for studying nanoparticle synthesis and growth. Described here is a system for automating synthesis and data collection, allowing time-resolved XAS measurements at a synchrotron to be accurately combined with measurements made under identical conditions elsewhere, and promising the ability to use XAS with experiments in combinatorial chemistry. The primary components of this system are a commercial parallel processor and a custom flow cell. The system has been used to collect data on the synthesis of iron oxides from iron(II) acetylacetonate.

The relationship between the fraction of absorbed photosynthetically active radiation (ƒAPAR) and spectral vegetation indices (SVIs) is affected by various factors, including background effects and the view zenith angle of the sensor. This study investigated the effects of estimating ƒAPAR from multiple off-nadir airborne measurements acquired by the advanced solid-state array spectroradiometer (ASAS) during the First International Satellite Land Surface Climatology Project Field Experiment. Using atmospherically corrected data, ƒAPAR was estimated with both directional SVIs (normalized difference vegetation index (NDVI) and simple ratio (SR)) and PAR hemispherical reflectance (RPAR) calculated from PAR bidirectional reflectance factors for the seven viewing angles of ASAS. Very weak linear relationships were found between the ground-measured total ƒAPAR values and ASAS measurements, assumed to be due to the presence of varying amounts of senescent plant materials in the canopy. Exclusion of data collected in October when the canopy was fully senescent somewhat improved these relationships. However, correction of total ƒAPAR values by the fraction of green vegetation present (green ƒAPAR) provided substantial improvement. For both SVIs the highest coefficients of determination (r2 = 0.839 for NDVI; r2 = 0.890 for SR) were found at 15° in the backscattering direction decreasing to minimum values at ±45°, a trend thought to be associated with the effect of canopy structure on the SVIs. Although RPAR was not strongly correlated with either the total or the green ƒAPAR, it was related to the independently measured PAR flux reflected from the canopy indicating a potential for deriving PAR hemispherical reflectance from directional measurements for natural cover types such as grasslands.

Six sets of airborne advanced solid-state array spectroradiometer (ASAS) and ground modular multiband radiometer (MMR) remotely sensed bidirectional measurements acquired over one First International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment site in 1987 and 1989 were compared for the following parameters: bidirectional spectral reflectance factor, spectral hemispherical reflectance, simple ratio, and normalized difference vegetation index. ASAS at-sensor radiances were atmospherically corrected and converted to surface reflectance factors. Selected MMR bands were simulated with ASAS data, and hemispherical reflectance for both ground and airborne data sets was estimated using data collected only in or close to the solar principal plane. The shapes of the reflectance factor response curves (as a function of view zenith angle) were strongly affected by solar zenith angle and compared well between instruments. Off-nadir anisotropy in reflectance factors was comparable between sensors, while actual values of reflectance factors differed 2–35% relative between instruments in the green channel and 0–38% relative in the red channel. For the data set giving the overall closest agreement, ASAS reflectance factors differed from MMR values by 5–17% relative (0.3–1.8% absolute) in the green and 5–10% relative (0.2–0.5% absolute) in the red. These differences showed no correlation with solar zenith angle. Some of the differences were arbitrarily introduced by the 5° offset in view zenith angles (except nadir) between the two instruments. Other differences were caused by the discrepancy in solar zenith angle for some of the sets, variable deviations from the solar principal plane, hotspot and associated shadowing effects not consistently recorded by both instruments, and sampled ground area variations. Estimates of hemispherical reflectance compared very well between sensors, with differences of only 3–14% relative (0.3–1.6% absolute) in the green and 11–27% relative (0.8–2.4% absolute) in the red. For the ASAS data, using atmospherically corrected reflectance factors (instead of at-sensor radiances) significantly increased the values of the spectral vegetation indices (SVIs). Off-nadir anisotropy for the SVIs derived from both sensors' data sets was less than that observed for the bidirectional reflectance factors, and NDVI off-nadir deviations were much less than those of the simple ratio (SR). Large differences in the values of SR and NDVI between sensors indicate SVIs calculated from broadband (MMR) versus narrowband (ASAS) data are not comparable.