Residual orientation in injection‐moulded plaques of atactic‐polystyrene II: The effect of molecular weight

Injection moulding of polymers is a well‐established technique for the production of increasingly complex articles, and residual molecular orientation is a matter of considerable interest. A single matrix of commercial atactic polystyrene was systematically blended with deuterated polystyrene chains of five different weight fractions and the orientation investigated using small angle neutron scattering (SANS), optical birefringence and thermal shrinkage. The strengths and limitations of the experimental techniques used to measure residual orientation are explored and highlighted the unique contribution of SANS to observe ensemble averaged molecular orientation using deuterated polymers. The residual molecular orientation was found to vary with the molecular weight of the deuterated chains with an increase with increasing molecular weight. The observed correlations lead to a better understanding of the processing parameters that influence the degree of residual orientation on the molecular scale. Such information is valuable in the selection of the polymer matrix, mould design, and processing conditions. POLYM. ENG. SCI., 58:1332–1341, 2018. © 2017 Society of Plastics Engineers     

Residual orientation in injection‐moulded plaques of atactic‐polystyrene I: The effect of processing conditions

Injection moulded polymer articles often have residual macromolecular or crystalline orientation which can have a significant impact on the optical and mechanical properties of the moulded article. Small angle neutron scattering (SANS) was used to measure the molecular shape and orientation of deuterated blends of injection moulded polystyrene. For ～1‐mm‐thick mouldings of uniform rectangular cross‐section, the eccentricity in the SANS pattern gave a direct measure of the residual molecular orientation over the length scale ～100–1,500 Å. The residual orientation was found to vary significantly with injection moulding conditions with comparative residual orientation decreasing with decreasing mould fill‐time, and increasing with mould thickness and moulding temperatures. The orientation was found to be a minimum in the centre of the mould and highest near the surface and the average orientation at a particular position in the mould was found to be strongly correlated with the volume of material deposited as a solid skin layer during injection moulding. POLYM. ENG. SCI., 58:1322–1331, 2018. © 2017 Society of Plastics Engineers     

Adaptive reshaping of objects in (multiparameter) Hilbert space for enhanced detection and classification: an application of receiver operating curve statistics to laser-based mass spectroscopy

We propose a new approach to the classical detection problem of discrimination of a true signal of interest from an interferent signal, which may be applied to the area of chemical sensing. We show that the detection performance, as quantified by the receiver operating curve (ROC), can be substantially improved when the signal is represented by a multicomponent data set that is actively manipulated by means of a shaped laser probe pulse. In this case, the signal sought (agent) and the interfering signal (interferent) are visualized by vectors in a multidimensional detection space. Separation of these vectors can be achieved by adaptive modification of a probing laser pulse to actively manipulate the Hamiltonian of the agent and interferent. We demonstrate one implementation of the concept of adaptive rotation of signal vectors to chemical agent detection by means of strong-field time-of-flight mass spectrometry.     

Comparison of ICEJAM and RIVJAM Ice Jam Profile Models

A review and comparison of two numerical ice jam profile models is provided. The first is the RIVJAM model, developed at the National Water Research Institute in Canada. The second is the ICEJAM model, which was developed at the University of Alberta and which forms the basis of the solution algorithm in the ice jam calculation routine recently implemented in HEC-RAS. Both the RIVJAM and ICEJAM models solve an ice jam stability equation in conjunction with one-dimensional, steady, gradually varied flow, and both have the capacity to compute profiles for equilibrium and nonequilibrium ice jams. The focus of the investigation is to compare the analytical equations solved, the numerical solution approaches, the required boundary conditions, and the relative sensitivity of the models' calibration parameters. Similarities between the models' governing equations and solution techniques are illustrated through direct comparison of the analytical equations and through model application. Differences between the models' boundary conditions and relative success of calibration are illustrated through the application to case studies.     

Enhancement of the properties of pulsed laser-deposited carbon nitride by the synchronisation of laser and N2 gas jet pulses

In surface coatings technology, especially in carbon-based materials, the deposition of energetic species is acknowledged as one of the most important factors in producing hard coatings. Pulsed laser deposition (PLD) of carbon under vacuum creates such energetic species and so carbon films with very high hardness values have been reported. However, when PLD takes place in a gas ambient, the ablated carbon species are decelerated to an extent that depends on the background pressure. As a result, during CN_x deposition, although the carbon species react effectively with N₂ at the beginning of their trajectories, when they reach the substrate they usually do not have sufficient kinetic energy to form a hard coating. In this paper we describe a new technique that combines the intense environment of an expanding N₂ jet with low-pressure PLD to produce CN_x species that travel almost free of collisions and reach the substrate with high kinetic energies. This new configuration is based on the synchronised pulsing of a N₂ jet with the laser pulse. The CN films produced are shown to have an increased film hardness without suppressing the nitrogen content. Furthermore, electron energy-loss spectroscopy shows the layers to have a very high proportion of π bonding, which can be correlated to the existence of sp-hybridised carbon in the form of –CN bonds.     

Influence of milling media on the structure and agglomeration behaviour of some hardmetal powder

This paper presents the influence of milling media on the structure and morphology of WC–Co powders for sintered tools. WC–Co powders have been milled in two different organic media, acetone and isohexane. The characterisation of the as-milled samples has been done by X-ray diffraction, scanning electron microscopy (SEM) and differential scanning calorimetry. The mean crystallite size decreases with milling time for the samples processed in acetone, while in the case of isohexane, the crystallite size stays at a relatively constant value when increasing the milling duration. The calculated mean crystallite size is below 50?nm for any milling duration, with larger values for acetone (16–46 nm) as compared to isohexane samples (10–12 nm). The SEM revealed that the dried powder is composed of agglomerated submicronic particles, and at high magnification, the presence of nanoparticles is noticed. The density of the aggregates was linked to the polarity of the solvents, which influences the sedimentation kinetics.     

Validating the factor structure of the Self-Report Psychopathy Scale in a community sample.

Currently, there is no standard self-report measure of psychopathy in community-dwelling samples that parallels the most commonly used measure of psychopathy in forensic and clinical samples, the Psychopathy Checklist. A promising instrument is the Self-Report Psychopathy scale (SRP), which was derived from the original version the Psychopathy Checklist. The most recent version of the SRP (SRP-III; D. L. Paulhus, C. S. Neumann, & R. D. Hare, in press) has shown good convergent and discriminate validity and a factor structure similar to the current version of the Psychopathy Checklist (PCL-R; R. D. Hare, 1991, 2003). The analyses in the current study further investigated the viability of the SRP-III as a PCL-R-analogous measure of psychopathy in nonforensic and nonclinical samples by extending the validation process to a community sample. Using confirmatory factor analyses and logistic regressions, the results revealed that a four-factor oblique model for the SRP-III was most tenable, congruent with the PCL-R factor structure of psychopathy and previous research in which the SRP-III was administered to a student sample. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

BACTERIAL PRODUCTION OF LACTIC ACID IN SWEET WORTS

The growth of thermophile organisms in brewing sweet wort held at temperatures between 60° and 70°C results in the production of L-(+)-lactic acid. These organisms exhibit intermediate characteristics between Bacillus coagulans and Bacillus stearothermophilus.     

Improving WCET by applying worst-case path optimizations

It is advantageous to perform compiler optimizations that attempt to lower the worst-case execution time (WCET) of an embedded application since tasks with lower WCETs are easier to schedule and more likely to meet their deadlines. Compiler writers in recent years have used profile information to detect the frequently executed paths in a program and there has been considerable effort to develop compiler optimizations to improve these paths in order to reduce the average-case execution time (ACET). In this paper, we describe an approach to reduce the WCET by adapting and applying optimizations designed for frequent paths to the worst-case (WC) paths in an application. Instead of profiling to find the frequent paths, our WCET path optimization uses feedback from a timing analyzer to detect the WC paths in a function. Since these path-based optimizations may increase code size, the subsequent effects on the WCET due to these optimizations are measured to ensure that the worst-case path optimizations actually improve the WCET before committing to a code size increase. We evaluate these WC path optimizations and present results showing the decrease in WCET versus the increase in code size. A preliminary version of this paper entitled “Improving WCET by optimizing worst-case paths” appeared in the 2005 Real-Time and Embedded Technology and Applications Symposium. Wankang Zhao received his PhD in Computer Science from Florida State University in 2005. He was an associate professor in Nanjin University of Post and Telecommunications. He is currently working for Datamaxx Corporation. William Kreahling received his PhD in Computer Science from Florida State University in 2005. He is currently an assistant professor in the Math and Computer Science department at Western Carolina University. His research interests include compilers, computer architecture and parallel computing. David Whalley received his PhD in CS from the University of Virginia in 1990. He is currently the E.P. Miles professor and chair of the Computer Science department at Florida State University. His research interests include low-level compiler optimizations, tools for supporting the development and maintenance of compilers, program performance evaluation tools, predicting execution time, computer architecture, and embedded systems. Some of the techniques that he developed for new compiler optimizations and diagnostic tools are currently being applied in industrial and academic compilers. His research is currently supported by the National Science Foundation. More information about his background and research can be found on his home page, http://www.cs.fsu.edu/∼whalley. Dr. Whalley is a member of the IEEE Computer Society and the Association for Computing Machinery. Chris Healy earned a PhD in computer science from Florida State University in 1999, and is currently an associate professor of computer science at Furman University. His research interests include static and parametric timing analysis, real-time and embedded systems, compilers and computer architecture. He is committed to research experiences for undergraduate students, and his work has been supported by funding from the National Science Foundation. He is a member of ACM and the IEEE Computer Society. Frank Mueller is an Associate Professor in Computer Science and a member of the Centers for Embedded Systems Research (CESR) and High Performance Simulations (CHiPS) at North Carolina State University. Previously, he held positions at Lawrence Livermore National Laboratory and Humboldt University Berlin, Germany. He received his Ph.D. from Florida State University in 1994. He has published papers in the areas of embedded and real-time systems, compilers and parallel and distributed systems. He is a founding member of the ACM SIGBED board and the steering committee chair of the ACM SIGPLAN LCTES conference. He is a member of the ACM, ACM SIGPLAN, ACM SIGBED and the IEEE Computer Society. He is a recipient of an NSF Career Award.