Characterization of conducting polymer coated fabrics at microwave frequencies

Purpose – The purpose of this paper is to investigate microwave reflection, transmission, and complex permittivity of p-toluene-2-sulfonic acid doped conducting polypyrrole coated nylon-lycra textiles in the 1-18?GHz frequency with a view to potential applications in the interaction of electromagnetic radiation with such coated fabrics.

Design/methodology/approach – The chemical polymerization of pyrrole is achieved by an oxidant, ferric chloride and doped with p-toluene sulfonic acid (pTSA) to enhance the conductivity and improve stability. Permittivity of the conducting textile substrates is performed using a free space transmission method accompanied by a mathematical diffraction reduction method.

Findings – The real part of permittivity increases with polymerization time and dopant concentration, reaching a plateau at certain dopant concentration and polymerization time. The imaginary part of permittivity shows a frequency dependent change throughout the test range. All the samples have higher values of absorption than reflection. The total electromagnetic shielding effectiveness exceeds 80 percent for the highly pTSA doped samples coated for 3?h.

Originality/value – A non-contact, non-destructive free space method thin flexible specimens to be tested with high accuracy across large frequency range. The non-destructive nature of the experiments enables investigation of the stability of the microwave transmission, reflection, absorption and complex permittivity values. Moreover, mathematical removal of the diffraction enables higher accuracy.

Decomposition properties of PVA/graphene composites during melting-crystallization

Abstract The thermal decomposition of PVA and PVA composites during the melting-crystallization process is still unclear due to indistinct changes in chemical compositions. Using graphene as a model, the decomposition properties of PVA and PVA-graphene composites were systematically analyzed under multiple melting-crystallization cycles. And a series of isothermal decomposition experiments around the melting-crystallization temperature were carried out to simulate the corresponding decomposition kinetics. Based on multiple cycle melting-crystallization, the weight loss of PVA and PVA/graphene composites was successfully quantified. Further morphology investigation and chemical structure analysis indicated that the decomposition was non-uniformly distributed, rendering the possibility of crystallization for PVA and PVA/graphene composites after multiple heating-cooling cycles. In addition, isothermal decomposition analysis based on reduced time plot approach and model-free iso-conversional method indicated that Avrami-Eroffev model could well match the decomposition process of the neat PVA and PG-0.3 composite, while the Avrami-Eroffev and first order models could precisely forecast the decomposition of PG-0.9 composite. Both analyses during multiple cycle melting-crystallization and isothermal decomposition demonstrated that graphene served as decomposition accelerator in the whole thermal decomposition process, and particularly the decomposition of neat PVA and PVA/graphene composites was highly related to the band area ratios of C-H and O-H vibrations in Fourier transform infrared (FTIR) spectrum.

On the proximal Landweber Newton method for a class of nonsmooth convex problems

We consider a class of nonsmooth convex optimization problems where the objective function is a convex differentiable function regularized by the sum of the group reproducing kernel norm and (Formula presented.)-norm of the problem variables. This class of problems has many applications in variable selections such as the group LASSO and sparse group LASSO. In this paper, we propose a proximal Landweber Newton method for this class of convex optimization problems, and carry out the convergence and computational complexity analysis for this method. Theoretical analysis and numerical results show that the proposed algorithm is promising.

Limitations to free association and interpretation

A core challenge that emerged from the historically based critique of Freud's work that constitutes Freud Evaluated: The Completed Arc (Macmillan, 1991, 1997) was to Freud's claim that the basic rule of psychoanalysis for inquiring into the causes of symptoms was unaffected by his “suggestions.” That is, in demanding that the patient tell the analyst whatever came to mind with complete candor, the patient would not be led astray by the analyst's ideas about the possible causes of the symptoms. In this article, the assumptions underlying Freud's belief in the validity of the method of free association are made explicit and criticized. The basic indetermination inherent in interpreting material apparently recovered by the method is also made explicit. Some of the consequences of the method for psychoanalytic developmental theories and for deciding between the variant schools of psychoanalysis are set out.

The reliability and validity of Freud's methods of free association and interpretation.

Presents a response of the author on the reliability and validity of Freud's method of free association and interpretation. Data gathering in clinical setting of psychoanalysis; Claims for reliability and validity; View of Freud on determinism.

Least squares splines with free knots: global optimization approach

Splines with free knots have been extensively studied in regard to calculating the optimal knot positions. The dependence of the accuracy of approximation on the knot distribution is highly nonlinear, and optimisation techniques face a difficult problem of multiple local minima. The domain of the problem is a simplex, which adds to the complexity. We have applied a recently developed cutting angle method of deterministic global optimisation, which allows one to solve a wide class of optimisation problems on a simplex. The results of the cutting angle method are subsequently improved by local discrete gradient method. The resulting algorithm is sufficiently fast and guarantees that the global minimum has been reached. The results of numerical experiments are presented.

Static and metadynamic recrystallization of interstitial free steels during hot deformation

A rapid method was used to identify kinetics of the recrystallization for two IF (Interstitial Free) steels which have different phosphorous and boron contents. The static and metadynamic softening behaviour of the materials for a range of strain rates and temperatures were quantified. The critical strain for initiation of strain independent softening was estimated for the IF steels in respect to the time for 50 percent softening after deformation. The results showed that the strain for the initiation of strain independent softening (often referred to as metadynamic recrystallization) varies with the Zener Hollomon parameter. Classic static recrystallization was observed at strains below the strain independent softening for all processing conditions and the strain rate had a strong effect on the time for strain independent softening. Results also revealed that static and metadynamic recrystallization was delayed owing to the phosphorous and boron alloying elements. Hence, the large strain at above no-recrystallization temperature may be required for the early stage of Finishing Stands Unit (FSU) in hot strip rolling mills to initiate austenite grain refinement of phosphorous and boron added IF steels.

Parallelization of the discrete gradient method of non-smooth optimization and its applications

We investigate parallelization and performance of the discrete gradient method of nonsmooth optimization. This derivative free method is shown to be an effective optimization tool, able to skip many shallow local minima of nonconvex nondifferentiable objective functions. Although this is a sequential iterative method, we were able to parallelize critical steps of the algorithm, and this lead to a significant improvement in performance on multiprocessor computer clusters. We applied this method to a difficult polyatomic clusters problem in computational chemistry, and found this method to outperform other algorithms.

Dielectric characterization of conducting textiles using free space transmission measurements: accuracy and methods for improvement

The dielectric behaviour of in-situ polymerized thin polypyrrole (PPy) films on synthetic textile substrates were obtained in the 1–18 GHz region using free space transmission and reflection methods. The PPy/para-toluene-2-sulphonic acid (pTSA) coated fabrics exhibited an absorption dominated total shielding effectiveness (SE) of up to −7.34 dB, which corresponds to more than 80% of incident radiation. The permittivity response is significantly influenced by the changes in ambient conditions, sample size and diffraction around the sample. Mathematical diffraction removal, time-gating tools and high gain horns were utilized to improve the permittivity response. A narrow time-gate of 0.15 ns produced accurate response for frequencies above 6.7 GHz and the high gain horns further improved the response in the 7.5–18 GHz range. Errors between calculated and measured values of reflection were most commonly within 2%, indicating good accuracy of the method.

Multiphase material modelling by multiscale particle-in-cell method

A particle-based method for multiscale modeling of multiphase materials such as Dual Phase (DP) and Transformation Induced Plasticity (TRIP) steels has been developed. The multiscale Particle-In-Cell (PIC) method benefits from the many advantages of the FEM and mesh-free methods, and to bridge the micro and macro scales through homogenization. The conventional mesh-based modeling methods fail to give reasonable and accurate predictions for materials with complex microstructures. Alternatively in the multiscale PIC method, the Lagrangian particles moving in an Eulerian grid represent the material deformation at both the micro and macro scales. The uniaxial tension test of two phase and three-phase materials was simulated and compared with FE based simulations. The predictions using multiscale PIC method showed that accuracy of field variables could be improved by up to 7%. This can lead to more accurate forming and springback predictions for materials with important multiphase microstructural effects.

The effect of smoke-free policies on revenue in bars in Tasmania, Australia

Objective: To examine the impact of smoke-free policies on revenue in Tasmanian bars.

Method: Monthly sales turnover from January 2002 to March 2007, provided by the Australian Bureau of Statistics was analysed. There were two outcome measures: (1) the ratio of monthly bar sales turnover in Tasmania to monthly bar sales turnover in four other Australian states, and (2) the ratio of monthly bar turnover to monthly retail turnover in Tasmania. Linear regression was used to assess the impact of the smoke-free policy on expenditure.

Results: The smoke-free policy had no effect on sales turnover.

Conclusion: The smoke-free policy protects hospitality workers and patrons from exposure to secondhand smoke and has had no adverse effect on sales turnover.

The effect of smoke-free policies on electronic gaming machine expenditure in Victoria, Australia

Objective: To examine the impact of smoke-free policies in Victorian gambling venues on electronic gaming machine (EGM) expenditure.

Method: Monthly EGM expenditure from July 1998 to December 2005, provided by the Victorian Commission for Gambling Regulation and the Office of the Liquor and Gambling Commissioner in South Australia, was analysed. The outcome measure was the ratio of monthly expenditure for Victoria to monthly expenditure in South Australia. Intervention analysis and autoregressive integrated moving average modelling were used to assess the impact of the smoke-free policy on expenditure.

Results: The smoke-free policy resulted in an abrupt, long-term decrease in the level of EGM expenditure. The mean level of monthly expenditure decreased by approximately 14%.

Conclusion: The smoke-free policy not only protects hospitality workers and patrons from exposure to secondhand smoke but has also had an impact on slowing gambling losses.

Providence and method : Herbert Butterfield and the interpretation of history

This thesis presents an extended critical analysis of the methodological thought of the Cambridge historian Herbert Butterfield (1900-1979). It is based on the full range of his published works, as well as unpublished material. It is a contribution to the history of historiography, and to the theory of history. The thesis concentrates on the relationship between Butterfield’s views on historical research and historiographical narration, and his concept of a ‘historical process’ which was the expression of a ‘providential order’. The principal problem in Butterfield’s writings is the contradiction between his advocacy of a ‘technical history’ seen as free and independent of any interpretative presupposition, and his belief in Providence and its utilisation in the course of his historiography. Firstly, the thesis argues that Butterfield employs his own presuppositions even without making explicit references to his belief in Providence. Secondly, it explains why he embraced and advocated two contradictory standpoints. Butterfield’s position is best clarified with reference to the content of his Christian beliefs. It is argued that Butterfield regarded all non-Christian interpretations of history as distorting oversimplifications. They were for him not fully scientific and rigorous, because they selected some phenomenon, or principle, or institution arising within human history and made it the central interpretative principle. He saw his own practice as exempt from this criticism. This thesis argues that Butterfield’s position is nevertheless interpretative. However, it is argued that Butterfield’s critique of ideologically based historiographic distortions and oversimplifications is important in the assessment of rival interpretations of history.

Intelligent clothing for automated recognition of human physical activities in free-living environment

This paper presents an intelligent clothing framework for human daily activity recognition using a single waist-worn tri-axial accelerometer sensor coupled with a robust pattern recognition system. The activity recognition algorithm is realized to distinguish six different physical activities through three major steps: acceleration signal collection/pre-processing, wavelet-based principle component analysis, and a support vector machine classifier. The proposed activity recognition method has been experimentally validated through two batches of trials with an overall mean classification accuracy of 95.25 and 94.87%, respectively. These results suggest that the intelligent clothing is not only able to learn the activity patterns but also capable of generalizing new data from both known and unknown subjects. This enables the proposed intelligent clothing to be applied in a comfortable and in situ assessment of human physical activities, which would open up new market segments to the textile industry.

FEM calibrated ARMAX model updating method for time domain damage identification

Due to environmental loads, mechanical damages, structural aging and human factors, civil infrastructure inevitably deteriorate during their service lives. Since their damage may claim human lives and cause significant economic losses, how to identify damages and assess structural conditions timely and accurately has drawn increasingly more attentions from structural engineering community worldwide. In this study, a fast and sensitive time domain damage identification method will be developed. To do this, a finite element model of a steel pipe laid on the soil is built and the structural responses are simulated under different damage scenarios. Based on the simulated data, an Auto Regressive Moving Average Exogenous (ARMAX) model is then built and calibrated. The calibrated ARMAX model is used to identify different damage scenarios through model updating process using clonal selection algorithm (CSA). The results demonstrate the application potential of the proposed method in identifying the pipeline conditions. To further verify its performance, laboratory tests of a steel pipe laid on the soil with and without soil support (free span damage) are carried out. The identification results of pipe-soil system show that the proposed method is capable of identifying damagein a complex structural system. Therefore, it can be applied to identifying pipeline conditions.