On managing the human factors engineering of hybrid productionsystems

In the transition toward total automation, contemporary manufacturing systems are predominantly composed of production equipment that is neither completely manual or automated. The development of these systems, identified as hybrid production systems, employ and integrate the capacities of human operators with intelligent machines. It is argued that human activities in hybrid automated systems are critical in achieving productivity gains. Given this importance, hybrid systems must be designed to optimize production. Optimal human factors engineering is possible only when engineers and their management are aware of the technical challenges, created by hybrid systems, and the range of options available for meeting these challenges. The authors describe these challenges and their possible solutions, specifically targeted to the management of engineering and technology-based organizations     

Coralline hydroxyapatite: a bone graft alternative in foot and ankle surgery

The use of coralline hydroxyapatite has become a viable bone grafting alternative. Its efficacy has been well established through multiple human and animal studies. Coralline hydroxyapatite enhances osteogenesis by providing a biocompatible lattice for the passage and assembly of vascular, fibroblastic, and osteoblastic tissues. It also provides support for surrounding osseous structures. The uses of this material are expanding into the realm of foot and ankle surgery. Its consideration as an appropriate bone graft substitute as well as multiple case studies demonstrating its surgical applicability are discussed. The implants utilized at Thorek Hospital and Medical Center over the past eight years, with an average follow-up of three and one-half years, have proven to be a valuable resource for augmentation where an osseous defect has occurred.     

Autocrine secretion of TGF-beta 1 and TGF-beta 2 by pre-adipocytes and adipocytes: a potent negative regulator of adipocyte differentiation and proliferation of mammary carcinoma cells

Concurrent and longitudinal associations between cognitive and affective personality variables--intellectual efficiency (IE), anxiety, and hostility--and observer ratings of physical health were examined in 3 longitudinal samples of women: Mills Longitudinal Study (n = 101); Radcliffe Study (RS, n = 118); and University of California, San Francisco Study (n = 44). Observer ratings of health were based on participants' reports of health problems. The California Psychological Inventory (H. G. Gough, 1996) IE, Hostility, and Anxiety Scales were used in all studies at Times 1 and 2, except in RS, when at Time 1 the Zung Anxiety (W. K. Zung, 1971) and the Profile of Mood States (D. M. McNair, M. Lorr, & L. F. Droppleman, 1971) Hostility Scales were used. In the majority of analyses, IE was positively associated with good health, and Anxiety and Hostility were negatively associated with health. IE was the strongest independent predictor of health, indicating that cognitive characteristics may have an important role in health and should be examined further.     

Response surface methodology in optimization of a divided wall column

dividing wall column (DWC) is a thermally coupled distillation system with a high energy efficiency that requires lower space and investment compared to the conventional column system. The design of a DWC involves a number of structural and process parameters that need to be optimized simultaneously to improve energetic and economic potential and reduce space requirement. We used response surface methodology (RSM) to optimize DWC nonlinearly and to figure out the effect of parameters and their interactions on energy consumption, product quality, and dimensions of a DWC. Results demonstrate that process variables have significant effects on the energy efficiency of a DWC as compared to the effect of structural variables. The optimum DWC parameters can be found by RSM with minimal simulation runs and the prediction results of RSM agree well with the rigorous simulation results.     

Effects of the slip boundary condition on dynamics and pull-in instability of carbon nanotubes conveying fluid

This paper addresses the effects of the slip boundary condition on dynamics and pull-in instability of carbon nanotubes (CNTs) containing internal fluid flow. Both the clamped–clamped and the cantilever boundary conditions are considered. The structure of CNTs is modelled using the size-dependent strain gradient theory (SGT) of continuum mechanics. It is shown that the Knudsen number (Kn) has a significant effect on the static and dynamic CNT response due to pull-in voltage loading and the existence of the instability region.     

Computational fluid dynamics on the hydrodynamic characteristics of the conical cap tray

This paper addresses an investigation on the hydrodynamic behavior of a new type of cap trays called conical cap tray (ConCap tray). A 3-D computational fluid dynamics model was developed to predict the hydrodynamics of the ConCap tray which is operated in the spray regime. The model considers two phase flow of gas and liquid in a VOF-like code framework. The homogeneous multiple size group model (MUSIG model) and shear stress transport (SST) turbulence model were implemented. Detailed insights into the hydrodynamic behavior of the inside of the cones were obtained. The relation between velocity, pressure and cross section area of the flow inside the cone also was formulated. The computational fluid dynamic (CFD) results show that the pressure variation in the cones forces the liquid on the tray to be highly turbulent, which leads to deform the interface to break up. Effect of different riser heights was also studied by CFD simulations. The results show that the riser height has a significant role in the hydrodynamics of the tray, especially in uniform gas distribution in the tray and reducing weeping rates.     

A field evaluation of driver eye and head movement strategies toward environmental targets and distractors

A new systems approach for evaluating field performance of drivers is presented in a practical experimental demonstration. The emphasis reflected in this paper is on driver head and eye movement behaviour toward environmental targets and distractors. A unique video technology set-up was designed to record eye and head movements. Simultaneous video-tapings of driver eye/head movements and the environmental scene were time synchronised. Two intersections (one busy and one quiet) were carefully selected and analysed for their static and dynamic visual targets and distractors. A subject made 40 repetitive left-turns alternately at busy and quiet intersections in a naturally moving traffic environment. Both head movement patterns and eye movement frequencies differed significantly between the two intersections. Results suggest that the eye and head movements are highly dependent upon the type of turn configuration, type and frequency of targets, type and frequency of distractors, and traffic control configurations.     

Dynamic analysis and intelligent control techniques for flexible manipulators: a review

This paper reviews literature on dynamic analysis and intelligent control techniques for flexible robot manipulators. First, a comparative dynamic analysis of flexible manipulators was presented and then control strategies were categorized and studied. Fuzzy logic, neural network, and genetic algorithm approaches were introduced and a range of contributions of such methods in flexible robot control were presented. A total of 115 papers were surveyed in this research, covering a sufficient depth in assessment of dynamic and control of flexible manipulator systems for the time span of 1970–2013.     

MATHEMATICAL MODELING OF HEAT AND MASS TRANSFER IN HOT GAS SPRAY SYSTEMS

A mathematical model is developed to study simultaneous heat and mass transfer in hot gas spray systems. The model is obtained by writing mass, energy, and momentum balances for both continuous and discontinuous phases. Governing equations along with suitable correlations for heat and mass transfer coefficients have been solved numerically. In order to develop a realistic model for such complicated systems, a droplet size distribution was implemented in the model instead of using an average size. A steady state spray-cooling problem is analyzed to illustrate the applicability of the model. To validate the mathematical model for this case, necessary data was collected and measured in commercial cement plants. A good agreement between plant data and the model was noticed in general, and results obtained from the model indicate that size distribution of water droplets and physical dimensions of the spray-cooling system are important parameters. This model is very useful in determining the so-called "critical operation condition" at which sludge formation at the bottom of spray-cooling systems will happen. The predicted parameters in spray-cooling systems both for droplet phase and gas phase aptly illustrate the ability of the model to treat the complex phenomena associated with two-phase flows.     

Using meta-heuristics for project scheduling under mode identity constraints

Mode identity and resource constrained project scheduling problem (MIRCPSP) is a substantial generalization of the well-known multi-mode problem. It arises when certain activities in the project are interdependent. That is, the set of all activities in the project are partitioned into disjoint subsets where all activities forming one subset have to be processed in the same mode. This paper addresses project scheduling problem with resource and mode identity constraints to minimize the project makespan. This problem is strongly NP-hard and three meta-heuristic algorithms namely imperialist competitive algorithm, simulated annealing and differential evolution are proposed to solve it. In order to improve the quality of the employed algorithms a local search and learning module is combined with the meta-heuristic algorithms. The performance of the algorithms is evaluated on 180 test problems by statistically comparing their solution in term of the objective function and computational times. The obtained computational results indicate that the integration of the learning module and the proposed algorithm is efficient and effective.