A machine-to-loop assignment and layout design methodology for tandem AGV systems with single-load vehicles

In this paper, we propose a method for design of tandem automated guided vehicle (AGV) systems with single-load vehicles. We consider the concurrent design of machines layout and AGV guide paths for a tandem system. Our goal is to devise a method that can achieve the following objectives: (1) maximise the workload balance between loops; (2) minimise the inter-loop flow; and (3) minimise the total flow distance. Our method solves the problem in four stages, considering the machines layout and the tandem paths at the same time. It assigns machines to loops, determines the layout of each loop, arranges loops on the floor, and finally designs a transportation centre to link the loops. We compare the performance of our method with a sequential design method that first determines the layout and then assigns the machines to loops. We solve a number of randomly generated problems for both methods. Results indicate that the proposed algorithm performs faster and achieves lower values of inter-loop flows and inter-loop flow distances.     

Comparing factor structures of adolescent psychopathology.

Research on the structure of adolescent psychopathology can provide information on broad factors that underlie different forms of maladjustment in youths. Multiple studies from the literature on adult populations suggest that 2 factors, Internalizing and Externalizing, meaningfully comprise the factor structure of adult psychopathology (e.g., Krueger, 1999) and presumably represent broad vulnerability for co-occurring disorders. Though this research was partially inspired by early work with children and adolescents (e.g., Achenbach & Edelbrock, 1984), the role of substance use in these models of youth psychopathology has not been fully explored. Toward this goal, we recruited 223 youths (10–17 years of age, M = 14.2) from mental health agencies and the community. We found evidence for a 3-factor model of youth psychopathology, including Internalizing (depression, generalized anxiety), Externalizing (conduct disorder, attention deficit, oppositional defiant disorder), and Substance Use (alcohol and cannabis). The 3-factor model showed the best fit to the data relative to other factor models tested, including across subsamples of adolescents who differed on level of psychopathology (treatment vs. community samples). Implications for the structure of adolescent psychopathology, including important developmental considerations, are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Gendered social forces: A review of the impact of institutionalized factors on women and girls' criminal justice trajectories.

Increasing arrest rates for girls and women have been documented both nationally and internationally and have propelled the development of promising theories of female antisocial behavior and crime. Nonetheless, many psychological theories focus exclusively on individual characteristics of women that promote criminality. Fewer theorists incorporate the influence of institutional and social policy factors in models of female antisociality and criminal justice involvement, despite growing evidence supporting the impact of these institutional factors on female crime. The present review expands existing conceptualizations by reviewing evidence about the extent to which the response of the criminal justice system disproportionately affects women across four key institutional domains: (1) processing and sentencing decisions, (2) relabeling and responding to youth status offenses, (3) arrests for drug offenses, and (4) pro and dual arrests for domestic violence incidents. Evidence largely supports the existence of gendered practices in the institutional response of the justice system to female crime, in that institutional changes have disproportionately influenced women's involvement in the justice system or have otherwise resulted in consequences that are different for women than men. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Preparation of ZIF-8—Pebax 1657 nanocomposite membranes for n-hexane/nitrogen separation as a representative of gasoline vapour recovery

Gasoline vapour emission is hazardous to both human health and the ecosystem and also results in capital loss, altogether revealing the necessity of its recovery. Some ZIF-8–Pebax flat nanocomposite membranes were fabricated by the method of solution casting and used for gasoline vapour recovery as represented by n-hexane vapour/nitrogen separation. Microporous ZIF-8 nanoparticles were synthesized and characterized by Fourier transform infrared (FTIR) and Brunauer–Emmett–Teller (BET) analysis. BET results revealed specific surface area, total volume, and average pore diameter of 940.8 m² · g⁻¹, 0.36 cm³ · g⁻¹, and 1.54 nm, respectively. Pure nitrogen and n-hexane vapour/nitrogen gas mixture permeabilities were measured through the membranes. There was a decline in both permeation rate and selectivity up to 5.0 wt.% of ZIF-8 loading and the next increment at their higher loadings to considerably more values that the pristine membrane. The maximum n-hexane vapour permeability and selectivity at 10.0 wt.% loading of ZIF-8 nanoparticles, the feed flow rate of 173 mL · min⁻¹, and permeate side pressure of −200 mbar were observed as 280.1 Barrer and 106.7, respectively, revealing 60.0% and 36.9% improvements compared with those of the pristine Pebax membrane. Observed 86%–92% n-hexane vapour recovery approves the successful application of the ZIF-8–Pebax nanocomposite membranes for n-hexane/nitrogen separation. The long-term separation performance of 5.0 wt.% ZIF-8 loaded nanocomposite membrane was improved by 76.5% compared with that of the pristine Pebax membrane.     

Thermodynamic and mechanical properties of amine-cured epoxy resins using group interaction modelling

The prediction of thermal and mechanical properties of amine-cured epoxy resins by group interaction modelling is presented. The derivation of the group interaction based approach to the prediction of macroscopic engineering properties of both linear and crosslinked epoxy resins is described with specific application to MY721 resin. The glass transition temperature, bulk and tensile modulus and linear thermal expansion coefficient of tetraglycidyl 4,4′-diaminodiphenylmethane (TGDDM) cured with 4,4′-diaminodiphenyl sulphone (DDS) are estimated using the model and compared with results from dynamic mechanical experiments. The glass transition of TGDDM/DDS is calculated to occur at approximately 248 °C and the reasons for a secondary peak in the spectrum cured to 180 °C are given. The bulk and tensile modulus of TGDDM/DDS are calculated to be 7.54 GPa and 5.34 GPa, respectively.     

Introducing and validating a new method for coupling neutronic and thermal-hydraulic calculations

In this study, a new and innovative method is introduced for analyzing neutronic and thermal-hydraulic calculation. For this aim, VVR-S research reactor was selected, and the calculation procedure was performed for it. WIMS, CITATION and COBRA-EN codes were used for investigation. Calculation model consists of two sub-models: neutronic and thermo-hydraulic. The neutronic model uses WIMS and CITATION codes for neutronic simulation of the reactor core and calculating flux and power distribution over it. WIMS code simulates the fuel assemblies and CITATION models the core. The thermal-hydraulic model uses COBRA-EN code for performing the relative calculation. In this study, FORTRAN 90 program is used for linking two sub-models and performing the calculation. The proposed procedure is performed for VVR-S analysis and finally, the obtained results are compared with the experimental results that show good agreement with it.