Enhanced Mechanical Properties and Corrosion Behavior of Biodegradable Mg-Zn/HA Composite

Metallurgical and Materials Transactions A - Magnesium (Mg) and its alloys have shown potential for use in the biomedical industry due to their excellent biological performance and biodegradability...     

Secondary population implementation in multi-objective evolutionary algorithm for scheduling of FMS

Any practical implementation of any multi-objective evolutionary algorithm (MOEA) must include a secondary population composed of all Pareto-optimal solutions found during its search process. Such an implementation with an active participation of solutions from the secondary population into the generational population of the genetic cycle is expected to improve the effectiveness of the MOEA. In this work, two kinds of secondary population, one with set of non-dominated solutions and another with a set of inferior solutions, accrued out of the generation cycles are constructed, and with different combinations of feeding of solutions from these two secondary populations, seven different implementation schemes are designed with an aim of intensifying the convergence and diversification capabilities of the genetic process of MOEA. All the schemes were implemented in a genetic algorithm-based MOEA designed to solve the scheduling problem with dual objectives for a flexible manufacturing system and tested with common experimental data. The performances of the schemes are compared, and the most appropriate implementation scheme is proposed.     

Application-Aware Acceleration for Wireless Data Networks: Design Elements and Prototype Implementation

A tremendous amount of research has been done toward improving transport-layer performance over wireless data networks. The improved transport layer protocols are typically application-unaware. In this paper, we argue that the behavior of applications can and does dominate the actual performance experienced. More importantly, we show that for practical applications, application behavior all but completely negates any improvement achievable through better transport layer protocols. In this context, we motivate an application-aware, but application transparent, solution suite called A³ (application-aware acceleration) that uses a set of design principles realized in an application-specific fashion to overcome the typical behavioral problems of applications. We demonstrate the performance of A³ through both emulations using realistic application traffic traces and implementations using the NetFilter utility.     

Impact of Inspected Buffers on Production Parameters of Construction Processes

This paper examines the production implications of quality control inspections conducted on the buffer between processes in a construction project by modeling the linkage between these processes. Inspection of partially completed work at the end of one activity but before the beginning of work by the next activity is fairly common. Work that is deemed to be of sufficient quality is then made available for the next activity. Work that is deemed insufficient requires rework, typically by the trade appropriate to the activity that fed into the buffer, to bring the work into compliance. This has implications for workload management for that trade, of course, as well as for the reliability of work flow to the successor or downstream processes. While such situations are common in all construction sectors, an example from the residential construction sector was examined via a simulation model augmented by field data collected from residential construction projects. The impacts of the work flow into the predecessor process, the inspection pass rate, and resource availability were examined. The inspection pass rate was found to dramatically affect the reliability of work flow, unless resources are unlimited. Furthermore, the inspection pass rate was found to be functionally related to the production parameters of the process.     

Scheduled WiFi using distributed contention in WLANs: algorithms,experiments, and case-studies

The ubiquitous adoption of WiFi introduces large diversity in types of application requirements and topological characteristics. Consequently, considerable attention is being devoted to making WiFi networks controllable without compromising their scalability. However, the main MAC protocol of WiFi, distributed coordination function (DCF), is a contention-based protocol using random backoff. Thus, operating under DCF, the access of channel is hard to control and nonpredictable. In order to provide controllability of channel access in WiFi, we propose Rhythm, a MAC protocol that achieves scheduled WiFi efficiently using distributed contention. By achieving scheduled WiFi, channel access can be controlled by manipulating the schedule decision. We evaluate the performance of Rhythm through analysis, experiments, and case-studies.     

A web-based remote interactive laboratory for Internetworking education

A Web-based remote interactive laboratory (RIL) developed to deliver Internetworking laboratory experience to geographically remote graduate students is presented in this paper. The onsite Internetworking program employs hands-on laboratories in a group setting that correlates with the constructivist and collaborative pedagogical approach. This paper discusses the pedagogical and technical considerations that influence the design and implementation of the remote laboratory environment given the constraints of the special hardware and learning outcomes of the program. For wide-ranging usability, the remote Internetworking (INWK) laboratory uses de facto networking standards and commercial and broad-band Internet connectivity to ensure real-time secure interaction with equipment. A four-tier role architecture consisting of faculty, local facilitators, remote facilitators, and students has been determined appropriate to maintain academic integrity and ensure good quality of interaction with the remote laboratory. A survey employing a five-point scale has been devised to measure the usability of the remote access INWK laboratory.     

Synthesis and characterization of functional gradient materials using Indian corals

The partial conversion of coralline hydroxyapatite (HA) into tricalcium phosphate (TCP) catalyzed by the thermal decomposition of silver oxide was investigated. The thermal analysis of HA powder mixed with 5 mol % Ag₂O indicated the decomposition of silver oxide to be around 550°C in the presence of HA. Subsequently a functional gradient structure was formed by spreading silver oxide on one surface of the HA compact of diameter 10 mm and then firing at 700°C in air. The X-ray powder diffraction analysis confirmed the formation of -TCP induced by the Ag₂O decomposition. The content of -TCP of the sintered pellet was found to decrease with the increasing depth from the surface of the pellet. In vitro solubility study in phosphate buffer of pH 7.2 showed the stability of the biphasic material as in between HA and TCP. © 2000 Kluwer Academic Publishers     

Microstructural and magnetic studies on P/M processed (Nd14.9Dy1.9)(Fe65.0Co8.0Cu1.0Ga1.0Nb0.7) B7.5 alloy

Sintered samples of (Nd_14.9 Dy_1.9) (Fe₆₅ Co₈ Cu_1.0 Ga_1.0 Nb_0.7)B_7.5 were prepared and subjected to stepwise annealing in the temperature range 875 K–675 K. The XRD and metallographic (optical and electron microscopy) studies reveal a multi-phase microstructure with each phase showing different solubility of the alloying additions. This alloy has T _C of 705 K with an intrinsic coercivity of 1000 kA/m and energy product of 250 kJ/m³ at RT. Solubility of Co into the matrix phase and that of Ga and Cu into the Nd-rich grain boundary phase are considered to be the main contributing factors for the significant enhancement in T _C and H _ci respectively of the multi-component alloy when compared to those of ternary NdFeB, wherein H _ci = 720 kA/m and T _C = 585 K.     

Reinforced Stone Columns in Weak Deposits: Laboratory Model Study

This paper investigates the performance of stone columns in a weak deposit such as peat. It evaluates the effects of reinforcing stone columns by jacketing with a tubular wire mesh and bridging reinforcement with a metal rod and a concrete plug. A series of plate loading tests was conducted on isolated stone columns installed in a soil bed consisting of a peat layer sandwiched between two layers of sand. The load–displacement characteristics of footings supported by stone columns were investigated by applying load to a circular plate supported on: (a) untreated soil; (b) soil treated with stone columns; and (c) soil treated with stone columns reinforced with the above reinforcing techniques. The work has shown that the settlement characteristics of the soil can be improved by installing stone columns and that a significant enhancement in the load–settlement response is achieved when the columns are reinforced by the various methods.     

A pattern based PSO approach for block matching in motion estimation

Block matching motion estimation is a popular method in developing video coding applications. A new algorithm has been proposed for reducing the number of search points using a pattern based particle swarm optimization (PSO) for motion estimation. The conventional particle swarm optimization has been modified to provide accurate solutions in motion estimation problems. This leads to very low computational cost and good estimation accuracy. Due to the center biased nature of the videos, the proposed approach uses an initial pattern to speed up the convergence of the algorithm. Simulation results show that improvements over other fast block matching motion estimation algorithms could be achieved with 31%～63% of search point reduction, without degradation of image quality.