Design and realization of ad-hoc VoIP with embedded p-SIP server

In this paper we design and implement the pseudo session initiation protocol (p-SIP) server embedded in each mobile node to provide the ad-hoc voice over Internet protocol (VoIP) services. The implemented p-SIP server, being compatible with common VoIP user agents, integrates the standard SIP protocol with SIP presence to handle SIP signaling and discovery mechanism in the ad-hoc VoIP networks. The ad-hoc VoIP signaling and voice traffic performances are analyzed using E-model R rating value for up to six hops in the implemented test-bed. We also conduct the interference experiments to imitate the practical ad-hoc VoIP environment. The analyzed results demonstrate the realization of ad-hoc VoIP services by using p-SIP server.     

Theoretical and experimental characterization of wettability of various nanolens arrayed polymer surfaces replicated with nanodimpled aluminum mold insert

Various types of polymer surfaces with a nanolens array, which has an entrant shape with a low aspect ratio, were fabricated and the wettability of the fabricated surfaces was evaluated in both theoretical and experimental ways. The nanolens array was replicated on three different polymer surfaces of polydimethylsiloxane (PDMS), cyclic olefin copolymer (COC), and polymethylmethacrylate (PMMA) by means of replica molding and hot embossing with a nanodimpled aluminum mold that was manufactured by a chemical oxidation process. From the theoretical and experimental evaluations of the wettability it was found that the measured contact angles were very similar with the theoretically estimated ones and also the hydrophilicity and hydrophobicity of the hydrophilic PMMA and hydrophobic PDMS, respectively, surfaces were reinforced by the nanolens array within the Wenzel wetting state.     

The effect of the aspect ratio on the hydrophobicity of microstructured polydimethylsiloxane (PDMS) robust surfaces

In this study, we have designed and fabricated robust hydrophobic surfaces that are composed of various micropillar arrays and investigated the effect of the aspect ratio (feature height/feature size) of the micropillar on the wettability of the fabricated surfaces. The robust, micropillar-arrayed surfaces were designed to yield the same Wenzel and Cassie water contact angles (CAs). According to our design rule, one can achieve an enhanced hydrophobic surface by increasing the height of the micropillars. The designed hydrophobic surfaces were fabricated by polydimethylsiloxane (PDMS) replica molding with photolithographically micropatterned SU-8 masters. The hydrophobicity properties of the fabricated PDMS surfaces were fully characterized theoretically and experimentally. From the theoretical and experimental results, it was found that the micropillars of an intrinsically hydrophobic material with a high aspect ratio enhance the hydrophobicity of the surface by increasing the surface roughness (in view of the Wenzel state) and the opportunities for the entrapment of air beneath a water droplet (the Cassie state).     

An agent-based workflow system for enterprise based on FIPA-OS framework

The paper describes what we have learned from implementing a multi-agent architecture used to support enterprise notions and principles for intelligent systems design. In the last couple of years, agent-based management systems have been widely used to monitor and control business design processes. In this paper, multi-agent architecture is proposed and applied to the workflow management system in ASE¹ (Advance Semiconductor Electronic) Inc., which is the world’s well-known largest provider of independent semiconductor for manufacturing services in assembly and test. The proposed FIPA-OS autonomous workflow management system uses a workflow co-ordination mechanism and an agent integration mechanism to enable the routine daily jobs error handle. Our vision for extending the FIPA-OS architectural elements to cover the development and implementation of generic web-Centric collaborative applications concludes the paper.     

Synthesis and characterization of novel blue azo‐dye derivatives containing acrylate group for dye‐based color filters

Abstract— Even though dyes have a fine resolution and good chromaticities, they are not widely used as coloring materials for color filters (CFs) due to their low thermal stability and chemical resistance. A series of azo‐dye derivatives, which consist of two cross‐linkable acrylate or methacrylate groups to improve thermal and chemical properties, have been synthesized and used to fabricate color filters. The spectral properties and chemical/thermal stabilities of the fabricated CFs were investigated by comparing dye‐based CFs, without a complicated dispersion process, but with pigment‐based CFs using dispersed pigment. Also, more properties including the development test and surface morphologies lithographic properties were studied. The synthesized azo dyes were characterized by elemental analysis, UV‐visible spectra, IR, mass, and ¹H‐NMR spectra.     

Organic wavelength‐converting‐film‐based hybrid planar white light‐emitting diodes

Abstract— In this study, organic wavelength‐converting films (WCFs) applied to InGaN blue LED‐based hybrid planar WLED has been fabricated. The organic dye layer in the WCF was formed between the upper and bottom polymer sheets by using a simple roll‐laminating technique. Subsequently, the hybrid planar WLEDs have been fabricated based upon these films. The luminous efficiency of green WCF‐based hybrid planar WLEDs with a single blue LED chip was 34.6 lm/W and that of red‐WCF‐assisted green WCF‐based hybrid planar WLEDs was 27.3 lm/W under 20 mA. The use of WCF to fabricate hybrid planar WLEDs showed better stability than that of directly coating organic color‐convergence materials (CCMs) on the LED chips. It only decreased to about 10% of the initial wavelength‐converting intensity after 1 hour of continual operation at 20 mA.     

Device reliability under electrical stress and photo response of oxide TFTs

Abstract— The stability of oxide TFTs has been the main focus of this research and is probably the most crucial requirement for the successful application to flat‐panel displays. Although the high Fermi level of oxide semiconductors makes TFTs basically stable under electrical stress, the device reliability under diverse variations of electrical stress is affected by materials such as active semiconductors and gate insulators, processes for the formation of back/front channels and passivation layers, and device configurations among other things. How these factors affect the device reliability have been investigated and a review of the stability is presented. In addition, several categories of the light instability of oxide TFTs is presented and the origin is discussed.     

Design of a sliding mode controller for an automatic guided vehicle and its implementation

In this paper, a control scheme that combines a kinematic controller and a sliding mode dynamic controller with external disturbances is proposed for an automatic guided vehicle to track a desired trajectory with a specified constant velocity. It provides a method of taking into account specific mobile robot dynamics to convert desired velocity control inputs into torques for the actual mobile robot. First, velocity control inputs are designed for the kinematic controller to make the tracking error vector asymptotically stable. Then, a sliding mode dynamic controller is designed such that the mobile robot’s velocities converge to the velocity control inputs. The control law is obtained based on the backstepping technique. System stability is proved using the Lyapunov stability theory. In addition, a scheme for measuring the errors using a USB camera is described. The simulation and experimental results are presented to illustrate the effectiveness of the proposed controller.     

Development of a sequential robust–tolerance design model for a destructive quality characteristic

Robust design (RD) and tolerance design (TD) have received much attention from researchers and practitioners for more than two decades, and a number of methodologies for modeling and optimizing the RD and TD processes have been studied. However, there is ample room for improvement. Because most existing research considers RD and TD as separate research fields, the primary objective of this paper is to develop a sequential robust–tolerance design method to jointly determine the best factor settings and the closed-form solutions for the optimal specification limits. We then apply the proposed method to a destructive quality characteristic. Finally, a case study and sensitivity analyses are performed for verification purposes, and further studies are discussed.     

A new energy harvest system with a hula-hoop transformer, micro-generator and interface energy-harvesting circuit

This study presents a synthesis of a new energy harvest system that consists of a hula-hoop transformer, a micro-generator and an interface energy harvest circuit. The hula-hoop transformer mainly comprises a main mass sprung in one translational direction and a free-moving mass attached at one end of a rod, the other end of which is hinged onto the main mass. The transformer is capable of transforming linear reciprocating motions to rotary ones based on the concepts similar to the hula hoop motions. The transformer is subsequently integrated with a miniaturized rotary generator in size of 10?×?10?×?2?mm³ and its compact energy harvest circuit chip. The designed generator consists of patterned planar copper coils and a multi-polar hard magnet ring made of NdFeB. The genetic algorithm (GA) is next applied to optimize the critical dimensions of the miniaturized generator. The optimized generator offers 4.5 volt and 7.23?mW in rms at 10,000?rpm. With micro-generator successfully fabricated, a novel energy harvest circuit employing a new dual phase charge pump, power management circuit, a low dropout regulator and battery charger is designed and fabricated via the 0.35???m process. This charge pump circuit owns the merit of automatic conversion of low-power AC signals by the micro-generator to DC ones. Experiments were conducted to show the favorable performance of the proposed energy harvest system. This is the first work that invents a motion transformer from ubiquitous reciprocating to rotational motions. In this way, higher-efficient energy conversion via compact-sized rotational electromagnetic generators can be realized as opposed to popular piezoelectric structures.