Experimental Study on Hybrid Cryogenic and Plasma-Enhanced Turning of 17-4PH Stainless Steel

This article presents machinability of 17-4PH stainless steel using a hybrid technique composed of plasma-enhanced turning and cryogenic turning. First of all, using some primary experimental tests and nonlinear regression, a mathematical model was developed for surface temperature of uncut chip as a function of plasma current and cutting parameters. Then, the influence of cutting speed (V_c), feed (f), and surface temperature of uncut chip (T_sm) was studied on surface roughness (R_a), cutting force (F_z), and tool flank wear (V_B). The results show that hybrid turning (HYT) is able to lower the main cutting force and tool flank wear in comparison with conventional turning. In addition, surface roughness was improved except for high level of surface temperature of uncut chip. However, hardness measurement of machined workpiece showed that HYT does not change the hardness of machined surface.     

The Electrochemical Behavior of Au/AuNPs/PNA/ZnSe-QD/ACA Electrode Towards CySH Oxidation

Nano-Micro Letters - This work describes the electrochemical behavior of azodicarboxamide (ACA) film immobilized on the surface of penicillamine (PNA)/ZnSe-quantum dot (ZnSe-QD) gold nanoparticle...     

Hot tensile properties and microstructural evolution of as cast NiTi and NiTiCu shape memory alloys

Hot tensile properties of as cast NiTi and NiTiCu shape memory alloys were investigated by hot tensile test at temperature range of 700–1100 °C using the strain rate of 0.1 s⁻¹. The NiTi alloy exhibited a maximum hot ductility at temperature range of 750–1000 °C, while the NiTiCu alloy showed it at temperature range of 800–1000 °C. It was found that at temperatures less than 750 °C, diffusion-assisted deformation mechanism was inactive leading to semi-brittle type of failure and limited ductility in both alloys. Also it was found that at temperature range of 800–1000 °C, dynamic recrystallization is dominant leading to high ductility. Likewise, the fracture surface of the specimens presenting the maximum hot ductility showed an ideal type of ductile rupture in which they gradually pulled out to a fine point. On the other hand, the decline in ductility occurred at the temperatures above 1000 °C was attributed to the liquid phase formation leading to interdendritic and intergranular type of fracture.     

Building information modeling for sustainable design and LEED rating analysis

Today, there is a high level of demand for sustainable buildings. The most important decisions regarding a building's sustainable features are made during the design and preconstruction stages. Leadership in Energy and Environmental Design (LEED^®) is the most widely adopted sustainable building rating system in the United States. For projects pursuing LEED^® certification, designers have to conduct in-depth sustainability analyses based on a building's form, materials, context, and mechanical-electrical-plumbing (MEP) systems. Since Building Information Modeling (BIM) allows for multi-disciplinary information to be superimposed within one model, it creates an opportunity to conduct these analyses accurately and efficiently as compared to the traditional methods. In this exploratory research, a case study was conducted on Salisbury University's Perdue School of Business building to demonstrate the use of BIM for sustainable design and the LEED^® certification process. First, a conceptual framework was developed to establish the relationship between BIM-based sustainability analyses and the LEED^® certification process. Next, the framework was validated via this case study. The results of this study indicate that documentation supporting LEED^® credits may be directly or indirectly prepared using the results of BIM-based sustainability analyses software. This process could streamline the LEED^® certification process and save substantial time and resources which would otherwise be required using traditional methods.     

Optimal Cycle Times in a Two-Stage Serial System With Set-Up and Inventory Costs

Two 2-stage serial production systems under constant average demand rate and infinite horizon are considered. The first and the simpler system assumes zero final product inventory; while the second assumes it nonzero but with a continuous demand. The stages have finite production rates greater than or equal to the demand rate and operate with periodic start-ups and shutdowns. No stock-outs are allowed in the inventories. Analytical results for determining a cyclic schedule with the minimum sum of set-up and inventory costs are presented. The optimal lot sizing policy for the first system involves integer splitting/merging of lots; however noninteger split/merge policy may be optimal in some instances of the second.     

Performance characterization of a non‐linear system as both an adaptive notch filter and a phase‐locked loop

The behaviour of a non‐linear dynamical system is described. The system may be characterized as an adaptive notch filter, or alternatively, as a phase‐locked loop. Either way, the system has the inherent capability of directly providing estimates of the parameters of the extracted sinusoidal component of its input signal, namely its amplitude, phase and frequency. The structure and mathematical properties of the system are presented for two cases of fixed‐frequency and varying‐frequency operation. The effects of parameter setting of the system on its performance are studied in detail using computer simulations. Transient and steady‐state behaviour of the system are studied in the presence of noise. Simplicity of structure, high noise immunity and robustness and the capability of direct estimation of amplitude, phase and frequency are the salient features of the system when envisaged as an adaptive notch filter or a phase‐locked loop. Copyright © 2004 John Wiley & Sons, Ltd.     

Technetium-99m-MIBI myocardial SPECT: supine versus right lateral imaging and comparison with coronary arteriography

Myocardial perfusion SPECT using the prone position improves inferior wall counts and decreases motion problems as compared with the usual supine position. Nonetheless, it is not suitable for women. In addition, it is associated with artifactual anteroseptal defects and hot spots. METHODS: The right lateral (RL) position was evaluated instead of the prone position in 72 patients (26 women). RL imaging was performed immediately after the supine imaging during a routine 2-day 99mTc-sestamibi exercise protocol. The SPECT images were scored semiquantitatively by three physicians. Moreover, regional myocardial counts, as well as extent and severity of defects, were assessed by quantitative polar map analysis. RESULTS: All patients tolerated the RL position well and there was no significant patient movement in either position. Higher inferior myocardial counts per pixel were observed in the RL than in supine images. Inferior wall defects (especially mild ones) were more common in the supine than the RL images, whereas defects in other regions were not different. Quantitative analysis confirmed these findings. Analysis of 34 patients with recent coronary arteriography revealed an overall coronary artery disease (CAD) supine- and RL-imaging specificity of 50% and 75%, respectively, and the sensitivities of both were 93%. Right CAD sensitivity, specificity and normalcy rates for the supine position were 100%, 44% and 55%, whereas those of the RL position were 94%, 75% and 90%, respectively. CONCLUSION: The RL position improves CAD diagnostic accuracy, particularly right CAD, without significant artifacts in other myocardial regions. Unlike the prone position, the RL position is well tolerated by both women and men.     

Superfluid density and critical current of3He in confined geometries

Superfluid³He in severely confined geometries is studied in the Ginzburg-Landau limit. Both A and B phases are analyzed in narrow slabs and in small cylinders. Physically measurable quantities include the superfluid density and the critical current, which are significantly suppressed by the boundaries. Related alterations in the phase diagram are also considered. For small lateral dimensions, the A phase can be favored even well below the polycritical pressure.     

Mitogen-activated protein kinase is activated during IgG-mediated phagocytosis, but is not required for target ingestion

This meta-analysis quantitatively summarized the developmental influence and the effects of locomotor experience as well as the benefits of locomotor practice, locomotor assistance, and active searching patterns on children's search performance. Based on specific criteria, a search of a database and reference lists identified 19 studies, including 1,029 children (510 boys and 519 girls) from 4 to 144 months of age. Outcome measures of spatial performance were converted to 83 effect sizes that reflected the effects of specific experimental characteristics. Analyses of variance indicated that with older children, locomotor activities are more important to their spatial searching. Locomotor status, searching patterns, locomotor assistance, test conditions, and test reliability were identified as moderator variables. In addition, locomotor training significantly improved children's spatial search. The results supported the hypothesis that children's development of spatial search skills is influenced by locomotor experience.     

Characterization of glass-ceramic corrosion and durability

The chemical durability of some selected glass-ceramic materials based on the Li₂O- (MnO, CaO)MgO---Al₂O₃---SiO₂ glass composition, has been determined by HCl, using the powder test.

The leachability of the glass-ceramic was gradually increased by replacing MgO with MnO, while it was decreased by addition of MnO instead of CaO. Calcium oxide had a retarding effect on the durability of the material when it was added instead of MgO and/or MnO. However, on the addition of Al₂O₃ in replacing Li₂O, the durability of the material was markedly improved. The leaching data were found to be dependent mainly on the proportion of the glass oxide constituents i.e. MgO/MnO, CaO/MnO and Li₂O/Al₂O₃ ratios present in the glasses.

The results were correlated to different views concerning the effect of various ions on the rate of interdiffusion between the crystalline-glass materials and leaching solution, the type, and proportions of the crystalline phases developed in glass-ceramics and residual glass phase.