Abstract: Extensive environmental concern associated with the disposal of solid plastic wastes has stirred tremendous interest in the production and use of sustainable biodegradable polymers. Among the vast variety of available materials, Polylactic Acid (PLA) standout as the most commercially viable mass produced resin to date. However, its low thermal and mechanical stability, excessive brittleness, and relatively higher cost have led to numerous research efforts in producing biodegradable polymer composite filled with natural organic fibers. This paper describes the preparation and the mechanical characteristics of a compression molded biodegradable composite made entirely of renewable raw materials. The composites were reinforced with pulverized palm, kenaf and alkali (1M NaOH:fiber in ratio 2:1) treated kenaf fibers, at a fiber mass proportion of 20 to 60% blended PLA and processed in a custom-built compression mold. SEM microscan revealed that the kenaf fiber has a mean diameter of 40μm, length 1236.6μm, and aspect ratio of 31 while the measured values for palm fiber was 58.7μm, 1041.2μm, and 17.7, respectively. All resulting composites showed significant enhancement in tensile strength. At 20, 40 and 60% fiber loading, the palm/PLA composite recorded tensile strength increment of 46.9, 47.8 and 36.6%, respectively. For the kenaf/PLA composite, greatest improvement was achieved at 40% fiber loading with alkali treated kenaf, with approximately 54% higher than the neat PLA while only 12.6% was recorded for the non-treated kenaf/PLA composite, signifying that the surface modification greatly improved fiber-matrix adhesion. SEM observations on the fracture surface showed similar findings. Compared to commercially available palm/Polypropylene (palm/PP) composite at 50% fiber loading, our measured tensile strength for the PLA composite loaded with 40% alkali treated kenaf fiber was still about 20% lower. Further enhancement in the mechanical characteristic of the kenaf/PLA composite is required to push for its wider utilization in the polymer industry.
Abstract: This paper presents a closed-form solution to determination of the position and orientation of a perspective camera with two unknown effective focal lengths for the noncoplanar perspective four point (P4P) problem. Given four noncoplanar 3D points and their correspondences in image coordinate, we convert perspective transformation to affine transformation, and formulate the problem using invariance to 3D affine transformation and arrive to a closed-form solution. We show how the noncoplanar P4P problem is cast into the problem of solving an eighth degree polynomial equation in one unknown. This result shows the noncoplanar P4P problem with two unknown effective focal lengths has at most 8 solutions. Last, we confirm the conclusion by an example. Although developed as part of landmark-guided navigation, the solution might well be used for landmark-based tracking problem, hand-eye coordination, and for fast determination of interior and exterior camera parameters. Because our method is based on closed-form solution, its speed makes it a potential candidate for solving above problems.
Abstract: The escalation of ambient CO2 concentration due excessive use of coal in power generation has put impetus on the development of technologies for utilization of vast and cheap resources available through out the world. Eco-scrub, Oxygen enriched and oxyfuel combustion are among the promising technologies guaranteeing the low carbon future. In our recent investigations, pulverized coal (Russian) was fired in a 20 kW down fired combustion rig under simulated exhaust gas recirculation. The effect of CO2 at burner inlet on the combustion efficiency, flue gas CO2 and NO emission was studied. The test conditions were essentially achieved by replacing the secondary air with a mixture of O2 and CO2 in different proportion. The test conditions do imitate the four key conditions for eco-scrub project. The basic theme under eco-scrub project is to use limited oxygen addition to reduce the volume of flue gas for processing, increase the efficiency of post combustion scrubbing due to higher CO2 levels and reduced the size and cost of post combustion capture. The exhaust gas CO2 was observed to increase linearly with increasing the CO2 at burner inlet. The flue gas concentration for 35% and 45% flue gas recycle was recorded to be 24% and 30% respectively. The NO emission was most of the time under the base line emission of 818 ppm. A maximum of 66% reduction was observed when the burner inlet CO2 was 45% and 21% O2. How ever an increase of 37% was seen when 80% of the secondary air was replaced with a 50%O2-50%CO2 mixture.
Abstract: This paper addresses the problem of sliding mode control design and adaptive sliding mode control design for robust stabilization of uncertain singular systems with guaranteed control performance. Based on the Lyapunov stability theorem, we solve two sufficient conditions for stabilization of the uncertain singular systems. The proposed sliding mode controller and adaptive sliding mode controller can reduce the effect of uncertainty. An electrical system is given to illustrate the validity of the proposed scheme. Simulation result shown that the adaptive sliding mode control design is better than sliding mode control design case.
Abstract: As consumer electronics continue to develop in size and scope, the battery power source with the limited life span poses an increasing economic challenge. This growing problem has motivated the development of the energy harvesters that can scavenge the ambient environment energy and convert it into the electrical energy for use of the wireless sensor nodes and the portable electronics. With the coupled field characteristics of structure to electricity, piezoelectric energy harvesters are under consideration as a means for converting the mechanical energy to the electrical energy, with the goal of realizing completely self-powered sensor systems. In this paper, the development of an enhanced coupled field model for the PCB energy harvester based on a previous model in the literature using a conservation of energy method is presented. Further, the laboratory experiments are carried out to evaluate the enhanced coupled field model and the other two previous models in the literatures. The comparison results show that the enhanced coupled field model can better predict the open-circuit of the PCB energy harvester with a proof mass bonded at the free end of the structure in order to increase the energy harvesting level of the system.
Abstract: A knife blade cutting experiment was performed to study the effect of clearance between two knife blades on cutting only one layer of a multi-layer thin film. The multi-layer thin films are made up of three major layers: a 0.1mm Polyethylene terephthalate (PET) layer, a 25 ~ 50 μm elastic plastic layer, and a 0.18 mm paper layer. The clearance between two knife blades is controlled by a micro manual stage. The cutting parameters are the clearance of knife blades, the edge of knife blades, and cutting speed. The relationships between layers to be cut and clearance between knife blades are measured using specific knife blades and a constant cut speed. Using the experimental results, several criteria for cutting paper layer are critically assessed. Through assessment of the criteria, the paper layer alone is practicably removed from multi-layer thin film. This experiment successfully provided a method to cut a specific layer but other layers of multi-layer thin film at once.
Abstract: In the present electric or hybrid vehicle, a PTC heater is adopted to provide heating function. In order to overcome the drawback of low efficiency of the PTC heater, a modified heat pump system structure was proposed to recover the waste heat which is generated by the subsystems of the electric vehicle. The recovered heat is transferred by the refrigerant and used to heat up the air that enters the cabin. In this paper, the electric vehicle battery pack is chosen as the target subsystem. A battery cell model was coded on the SC/Tetra platform and corrected according to the experiment data. The simulation results showed that the maximum heat generated by the battery modules (176 cells) under 1.5C discharging is about 356 W which could reduce 20% of the heat absorbed from the environment if a complete battery pack (400 cells) is used.
Abstract: It has important scientific and engineering applications for near-space platform to design the buoyancy-lifting aircraft with both bigger volume and higher aerodynamic efficiency. This paper provided a design of a new concept V-shaped airship which has a capacity of buoyancy-lifting configuration than the same-weight class conventional airship. In addition, two engines could provide rolling, yawing and pitching moments for the V-shaped airship by changing directions and creating different thrust. Based on the thick aerofoil, the geometry of this V-shaped configuration was then used to develop an aerodynamic estimating model for the V-shaped airship. It renewed estimating methods for the added mass, inertia, the forces and the moments including aerodynamic and engine thrust of the V-shaped airship. Then this paper described a 6 Degree of Freedom (DOF) dynamic model for the V-shaped airship. The open-loop disturbance characteristic of the dynamic model was analyzed across a range of flight conditions and the added mass of the V-shaped airship were compared with the same weight-class teardrop-shaped dull-hull airship. Finally, the characteristics of buoyancy and lift between V-shaped airship and dull-hull airship were compared at different velocity. The results show that the aerodynamic efficiency of the V-shaped airship is improved obviously from the same-weight class dull-hull airship across a range of flight velocity.
Abstract: The intent of this paper is to illustrate a personas system effective design to aid development of new products. This system would help a design team find and understand the lifestyle of target customers by using personas method in early concept development stage. In order to quickly realize market trends, easily collect customer requirements and readily integrate user opinions, the proposed system is capable of helping experts in different domains concurrently share their ideas in real time and discuss with each other without geographic limitation. In addition, a novel approach is proposed, named as ‘Personas Matrix’, to quantify the requirements which can accelerate the assessment of true needs. Finally, in order to validate the proposed system, a LED (Light-Emitting Diode) project was applied to test the functionality of the approach and the usefulness of the system thus helping the design team refine requirements, simplify requirement gathering, and prompt the assessment.
Abstract: In the case of hydraulic power system of ships or marine facilities, many kinds of mechanical, electrical, hydraulic components are connected to each other very complicatedly. It is very hard to disassemble or reconfigure the hydraulic system. Therefore there are increasing demands from industry for a stand-alone type actuator and a valve remote control system. Valve remote control system (VRCS) is a convenient system which it possible to operate the valves installed in the cargo or ballast tanks from the remote wheelhouse. This paper is dealing with a new stand-alone type hydraulic actuator for a valve remote control system. The stand-alone type hydraulic actuator consists of a gear pump, an AC motor, a check valve, a relief valve and a controller. We try to design and implement the stand-alone type hydraulic actuator and this tries to be verified through an experiment. This research is a contribution to simplify a hydraulic system, improve responsibility of dynamic power system, and reduce an energy loss in a ships or marine facilities.