High Speed Steel and WC Particle-Reinforced Composites Produce by Spray Forming

The process of spray forming utilized to fabricate WC particle-reinforced high speed steel composites has been studied. In addition, microstructures and mechanical properties of M2 high speed steel and its composites made by spray forming have been analyzed. The results show that the primary carbides of high speed steel are of two types: MC and MbC. With the increase in flight distance, the morphology of the primary carbides varies from fine fish-bone-like to islandlike and both bending strength and hardness increase. With the increase in volume fraction of WC reinforcement particles,hardness of the composites increases considerably, but bending strength, however, appears to be a decreasing tendency.     

Optimal Track Access Rights Allocation for Agent Negotiation in an Open Railway Market

In open railway access markets, a train service provider (TSP) negotiates with an infrastructure provider (IP) for track access rights. This negotiation has been modeled by a multiagent system in which the IP and the TSP are represented by separate software agents. One of the tasks of the IP agent is to generate feasible (and preferably optimal) track access rights, subject to the constraints submitted by the TSP agent. This paper formulates an IP-TSP transaction and proposes a branch-and-bound algorithm for the IP agent to identify the optimal track access rights. Empirical simulation results show that the model is able to emulate rational agent behaviors. The simulation results also show good consistency between the timetables that were attained from the proposed methods and those that were derived by the scheduling principles adopted in practice.     

Oscillation and convergence behaviours exhibited in an ‘unstable’ second‐order digital filter with saturation‐type non‐linearity

This letter explains the oscillatory behaviours exhibited in a second‐order digital filter with saturation‐type non‐linearity via the Hopf bifurcation theorem. It is shown that depending on the bifurcation parameter, the state variables may converge to zero even when the eigenvalues of the system matrix are outside the unit circle. Copyright © 2004 John Wiley & Sons, Ltd. abstract     

Tensile deformation mechanisms of polypropylene/elastomer blends reinforced with short glass fiber

Polypropylene hybrid composites reinforced with short glass fiber (SGF) and toughened with styrene–ethylene butylenes–styrene (SEBS) elastomer were prepared using extrusion and injection‐molding techniques. Moreover, hybrids compatibilized with SEBS‐grafted maleic anhydride (SEBS‐g‐MA) and hybrid compatibilized with PP grafted with maleic anhydride (PP‐g‐MA) were also fabricated. The matrix of the latter hybrid was designated as mPP and consisted of 95% PP and 5% PP‐g‐MA. Tensile dilatometry was carried out to characterize the fracture mechanisms of hybrid composites. Dilatometric responses showed that the elastic deformation was the dominant deformation mechanism for the SGF/SEBS/PP and SGF/SEBS‐g‐MA/PP hybrids. However, cavitation deformation prevailed over shearing deformation for both hybrids at the higher strain regime. The cavitation strain resulted from the debonding of glass fibers and from the crazing of the matrix in the SGF/SEBS/PP hybrid. In contrast, the cavitation was caused by the debonding of SEBS particles from the matrix of the SGF/SEBS‐g‐MA/PP hybrid. The use of PP‐g‐MA resulting in elastic deformation was the main mode of deformation in the low‐strain region for the SGF/SEBS/mPP and SEBS/SEBS‐g‐MA/mPP hybrids; thereafter, shearing appeared to dominate at the higher strain regime. This was attributed to the MA functional group improving the bonding between the SGF and PP. The correlation between fracture morphology and dilatometric responses also is presented in the article. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 441–451, 2003     

Crystallization behavior of polylactide matrix under the influence of nano‐magnetite

Iron oxide nanoparticle (Fe₃O₄) has gained remarkable research interest for various applications, from environmental to biological, because of its superparamagnetic properties and good biocompatibility. In this work, the nucleation effect of Fe₃O₄ in a polylactide (PLA) matrix under an influence of an alternating magnetic field was studied. The nanocomposite films that is, containing different concentrations of Fe₃O₄ (~8 nm) which were uniformly dispersed in the PLA matrix, were prepared via a solution casting method. The amplitude and frequency of the magnetic field impose great effects on the morphology and nucleation rate of PLA crystallization. Thermogravimetric analysis was used to study the thermal stability of Fe₃O₄/PLA and it showed that the thermal stability of Fe₃O₄/PLA was affected by the Fe₃O₄ content. Fourier transform infrared spectroscopy and X‐ray diffractometry indicated that Fe₃O₄ shows impeding effect to the crystallization of PLA. Based on the differential scanning calorimetry results, composite with 1% of Fe₃O₄ content could promote the crystallization of PLA but it would become an obstacle when 3% of Fe₃O₄ was added. The result of polarized optical microscopy also showed a good agreement that the incorporation of Fe₃O₄ could act as an effective nucleation regent to the composite film. POLYM. ENG. SCI., 59:608–615, 2019. © 2018 Society of Plastics Engineers     

Differential Effects of Estrogen and Progestin on Apolipoprotein B100 and B48 Kinetics in Postmenopausal Women

The distinct effects of the estrogen and progestin components of hormonal therapy on the metabolism of apolipoprotein (apo) B‐containing lipoproteins have not been studied. We enrolled eight healthy postmenopausal women in a placebo‐controlled, randomized, double‐blind crossover study. Each subject received placebo, conjugated equine estrogen (CEE, 0.625 mg/day) and CEE plus medroxyprogesterone acetate (MPA, 2.5 mg/day) for 8 weeks in a randomized order, with a 4‐week washout between phases. Main outcomes were the fractional catabolic rate (FCR) and production rate (PR) of apo B100 in triglyceride‐rich lipoproteins (TRL), intermediate‐density lipoproteins (IDL) and low ‐density lipoprotein (LDL) and of apo B48 in TRL. Compared to placebo, CEE increased TRL apo B100 PR (p = 0.04). CEE also increased LDL apo B100 FCR (p = 0.02), but this effect was offset by a significant increase in LDL apo B100 PR (p = 0.04). Adding MPA to CEE negated the CEE effects resulting in no significant changes in TRL apo B100 PR and LDL apo B100 FCR and PR relative to placebo. Relative to placebo, during CEE there was a trend toward a reduction in plasma apo B48 concentrations and PR (p = 0.07 and p = 0.12, respectively). Compared with CEE, CEE + MPA significantly increased TRL apo B48 FCR (p = 0.02) as well as apo B48 PR (p = 0.01), resulting in no significant changes in apo B48 concentration. Estrogen and progestin have independent and opposing effects on the metabolism of the atherogenic apo B100‐ and apo B48‐containing lipoproteins.     

Low cost inductor current sensing for power converters using feedback compensation

One of the key components in the current mode control of power converters is the sensing of inductor current. Traditional low cost implementation is to add a sensing resistor in series with the inductor to sense the inductor current. This will reduce the overall efficiency of the power converter. An alternative is to apply a current transformer to the inductor to sense its current. This however will significantly increase the cost of power converters. One low cost implementation is to add a resistor–capacitor network in parallel with the inductor so that the inductor current can be derived from the capacitor voltage. The problem of this implementation is that the capacitor voltage is very sensitive to temperature variations. In this paper, a simple feedback loop is applied to the sensed capacitor voltage based on the steady state duty ratio of power converters such that the sensed inductor current will be independent of temperature variations. The sensing element with feedback compensation can be applied to inductors fitted to power converters such as buck converters and boost converters. Although experimental studies based on a buck converter were carried out to illustrate the correctness of the new sensing technique, the proposed technique is applicable to other converter topologies.     

Investigating success factors in enterprise application integration: a case-driven analysis

This paper investigates Critical Success Factors (CSFs) in Enterprise Application Integration (EAI). An initial set of CSFs for EAI projects was created based on a review and synthesis of the literature in the general area of integration, including Enterprise Resource Planning (ERP) projects. A case analysis, involving a large financial services provider integrating its consumer banking systems, was used to validate the CSFs. The findings resulted in a more structured and holistic CSF model which identifies three broad groups of CSFs, namely (1) top management support, (2) overall integration strategy, and (3) EAI project planning and execution. Although EAI projects share many of the same CSFs as ERP projects and other information systems projects, issues related to the selection of the right EAI tool and emphasis on technology planning and enterprise architecture are distinguishing features of EAI projects. Some of practical implications of the research are that EAI projects require personnel with specific skills and expertise, business integration should precede technology integration, that availability of adapters is an important criteria in EAI tool selection and that some custom adapter development may be unavoidable if custom applications need to be integrated.