Development and material properties of new hybrid plywood from oil palm biomass

Shortage of wood as a raw material has forced wood-based industries to find alternative local raw materials. Currently, oil palm biomass is undergoing research and development (R & D) and appears to be the most viable alternative. This work examines the conversion of oil palm trunk (OPT) and oil palm empty fruit bunches (OPEFB) into new plywood and analyses its properties. We prepared five-ply veneer hybrid plywood (alternating layers of oil palm trunk veneer and empty fruit bunch mat) with different spread levels (300 g/m² and 500 g/m²) of resins (phenol formaldehyde and urea formaldehyde). We then studied the mechanical and physical properties of the plywood. The results show that hybridisation of EFB with OPT improves some properties of plywood, such as bending strength, screw withdrawal and shear strength. The thermal properties of the plywood panels were studied by thermogravimetric analysis (TGA). The panels glued with phenol formaldehyde with a spread level of 500 g/m² showed better thermal stability than the other panels. Scanning electron microscope (SEM) was used to study the fibre matrix bonding and surface morphology of the plywood at different glue spread levels of the resins. The fibre–matrix bonding showed good improvement for the hybrid panel glued with 500 g/m² phenol formaldehyde.     

Using DAG transformations to verify Euler/Venn homogeneous and Euler/Venn FOL heterogeneous rules of inference

In this paper we will present a graph-transformation based method for the verification of heterogeneous first order logic (FOL) and Euler/Venn proofs. In previous work, it has been shown that a special collection of directed acyclic graphs (DAGs) can be used interchangeably with Euler/Venn diagrams in reasoning processes. Thus, proofs which include Euler/Venn diagrams can be thought of as proofs with DAGs where steps involving only Euler/Venn diagrams can be treated as particular DAG transformations. Here we will show how the characterization of these manipulations can be used to verify Euler/Venn proofs. Also, a method for verifying the use of heterogeneous Euler/Venn and FOL reasoning rules will be presented that is also based upon DAG transformations .     

Railing for Safety: Job Demands, Job Control, and Safety Citizenship Role Definition.

This study investigated job demands and job control as predictors of safety citizenship role definition, that is, employees' role orientation toward improving workplace safety. Data from a survey of 334 trackside workers were framed in the context of R. A. Karasek's (1979) job demands-control model. High job demands were negatively related to safety citizenship role definition, whereas high job control was positively related to this construct. Safety citizenship role definition of employees with high job control was buffered from the influence of high job demands, unlike that of employees with low job control, for whom high job demands were related to lower levels of the construct. Employees facing both high job demands and low job control were less likely than other employees to view improving safety as part of their role orientation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Controllability and observability of 2D thermal flow in bulk storage facilities using sensitivity fields

To control and observe spatially distributed thermal flow systems, the controllable field and observable field around the actuator and sensor are of interest, respectively. For spatially distributed systems, the classical systems theoretical concepts of controllability and observability are, in general, difficult to apply. In this study, sensitivity fields were used to analyse the behaviour from input to state and from initial state to output. For the analysis of controllability and observability, a large-scale, bulk storage facility with coupled thermal flow of air and agro-products was used. Analysis of this system using the classical systems theory results in controllability and observability results that are dependent on the step size of the spatially discretised system. Due to matrix multiplications, inaccurate results are calculated if the step size is too small. Our findings indicate that input-state and initial-state output sensitivity fields provide sufficient information about the controllability and observability of large coupled spatially distributed systems, using finite-dimensional state space representation with small discretisation steps.     

Modelling of a self-led critical friend topology in inter-cooperative grid communities

For decades, much work has been done to increase the effectiveness and efficiency of job sharing amongst available computational resources. Resources can be organized into a variety of topologies, and recent work has shown that a decentralized distributed resource topology is a crucial but complicated scenario. This is because decentralized resources are normally grouped into independent virtual organizations (VOs) and isolated from each other by VO boundaries.To convey jobs across gaps between various virtual organizations, a novel resource topology called the self-led critical friend model (CFM) is proposed in this work. The CFM deals with trust credits between resources according to their historical collaboration records. This trust reveals a feasible, realistic, and transferable correlation to facilitate the resource selection process for job delegation between arbitrarily connected physical resources. Consequently, the CFM is able to overcome the constraints caused by virtual organization boundaries.Besides the theoretical model, a simulation-based implementation is carried out together with a complementary high-level community-aware scheduling protocol. After evaluating a number of compositional scenarios and criteria objectives, the observed results show the benefit of job scheduling across multiple VOs, as well as the capability of the self-led critical friend model as a novel cross-VO resource topology to represent and interconnect resources.     

A 122 TΩ Hz transimpedance bandwidth product BiCMOS optical sensor front-end with a 54.7 dB voltage-controlled photo-sensitivity range

An optical sensor front-end with integrated PIN photodiode in 0.6 μm BiCMOS technology intended for universal optical storage operation is presented. It is based on a mixed current conveyor and voltage amplifiers topology avoiding stability problems. The transimpedance is continuously variable and directly proportional to a voltage-controlled resistance. Another voltage-controlled resistor within a variable-gain voltage amplifier increases the photo-sensitivity range. A fixed-gain voltage amplifier and a current biasing of the current conveyor enable frequency bandwidth enhancement leading to a large transimpedance bandwidth product. A linearity error smaller than 2.8%, a photo-sensitivity range of 541 (54.7 dB) with the largest photo-sensitivity of 2468 mV/μW, an offset voltage <13.7 mV, a frequency bandwidth up to 277 MHz, a slew rate up to 377 V/μs, a transimpedance bandwidth product up to 122 TΩ Hz, and a maximum power consumption of <4.3 mW are achieved.     

An ecophysiological model of plant–pest interactions: the role of nutrient and water availability

Empirical studies have shown that particular irrigation/fertilization regimes can reduce pest populations in agroecosystems. This appears to promise that the ecological concept of bottom-up control can be applied to pest management. However, a conceptual framework is necessary to develop a mechanistic basis for empirical evidence. Here, we couple a mechanistic plant growth model with a pest population model. We demonstrate its utility by applying it to the peach–green aphid system. Aphids are herbivores which feed on the plant phloem, deplete plants’ resources and (potentially) transmit viral diseases. The model reproduces system properties observed in field studies and shows under which conditions the diametrically opposed plant vigour and plant stress hypotheses find support. We show that the effect of fertilization/irrigation on the pest population cannot be simply reduced as positive or negative. In fact, the magnitude and direction of any effect depend on the precise level of fertilization/irrigation and on the date of observation. We show that a new synthesis of experimental data can emerge by embedding a mechanistic plant growth model, widely studied in agronomy, in a consumer–resource modelling framework, widely studied in ecology. The future challenge is to use this insight to inform practical decision making by farmers and growers.     

Removal of chromium ions from aqueous solutions by polymer-enhanced ultrafiltration

This study deals with the removal of chromium species from aqueous dilute solutions using polymer-enhanced ultrafiltration (PEUF) process. Three water soluble polymers, namely chitosan, polyethyleneimine (PEI) and pectin were selected for this study. The ultrafiltration studies were carried out using a laboratory scale ultrafiltration system equipped with 500,000 MWCO polysulfone hollow fiber membrane. The effects of pH and polymer composition on rejection coefficient and permeate flux at constant pressure have been investigated. For Cr(III), high rejections approaching 100% were obtained at pH higher than 7 for the three tested polymers. With chitosan and pectin, Cr(VI) retention showed a slight increase with solution pH and did not exceed a value of 50%. An interesting result was obtained with PEI. The retention of Cr(VI) approached 100% at low pH and decreased when the pH was increased. This behavior is opposite to what one can expect in the polymer-enhanced ultrafiltration of heavy metals. Furthermore, the concentration of polymer was found to have little effect on rejection. Permeate flux remained almost constant around 25% of pure water flux.     

Socially Distributed Perception: GRACE plays social tag at AAAI 2005

This paper presents a robot search task (social tag) that uses social interaction, in the form of asking for help, as an integral component of task completion. Socially distributed perception is defined as a robot's ability to augment its limited sensory capacities through social interaction. We describe the task of social tag and its implementation on the robot GRACE for the AAAI 2005 Mobile Robot Competition & Exhibition. We then discuss our observations and analyses of GRACE's performance as a situated interaction with conference participants. Our results suggest we were successful in promoting a form of social interaction that allowed people to help the robot achieve its goal. Furthermore, we found that different social uses of the physical space had an effect on the nature of the interaction. Finally, we discuss the implications of this design approach for effective and compelling human-robot interaction, considering its relationship to concepts such as dependency, mixed initiative, and socially distributed cognition. An erratum to this article can be found at

---

     

The effect of biological studies of polyester composites filled carbon black and activated carbon from bamboo (Gigantochloa scortechinii)

The development of composites using various filler material increased significantly nowadays. Composite materials need to implement the biological and mechanicals impact in their life cycle. The carbon black (CB) and activated carbon (AC) from bamboo (Gigantochloa scortechinii) were used as filler in polyester composites. CB and AC were pyrolized to 700°C and activated with ZnCl₂. The composites were prepared with 40% filler loading. The degradation of the composites CB and AC (mechanical properties) to the soil burial test was determined. Tensile, flexural, impact and mass changes of the buried samples were investigated. The deterioration of the samples affected by the biological attack was confirmed by SEM studies. The assessment was done after 0, 3, 6, and 12 months of the biological exposure and the results were compared with the composites filled CaCO₃ (commercial filler) and cast polyester resin (as control). POLYM. COMPOS. 28:6–14, 2007. © 2007 Society of Plastics Engineers