A new classification system for dead zones in metal cutting

Chip formation in metal cutting often involves the formation of dead zones. These dead zones may influence tool life, roughness of the cut surface and the dimensional accuracy of the workpiece.

The present paper is intended to solve the lack of unambiguous terminology and definitions of different observed dead zone phenomena. The definitions of four principally different dead zones are based on the localization of the two separating cracks that form the chip back and the cut surface respectively.     

Calibration of low-rise multifamily residential simulation models using regressed estimations of transmission losses

In this study, we evaluated a proposed calibration (PC) approach for whole-building energy simulation models. This approach was based on a regression analysis of measured data collected during a time period when the global solar radiation was the lowest. The proposed approach was compared with a more conventional calibration approach with different degrees of complexity, starting from design stage (DS) assumptions, through audits, and lastly by refining the model with detailed measurements and numerical calculations. The evaluation was performed using measured data from two multifamily buildings located in Umeå, Sweden, and the IDA-ICE 4.61 simulation software. The best agreement between simulated and measured data was obtained with the PC approach. The monthly normalized mean bias error and the coefficient of variation were less than 5.0% and 6.0%, respectively. For the conventional calibration approach, detailed measurements and time-consuming numerical calculations were required to reach similar results.     

Degradation of polycyclic aromatic hydrocarbons (PAHs) in contaminated soils by Fenton's reagent: a multivariate evaluation of the importance of soil characteristics and PAH properties

In this study, we investigated how the chemical degradability of polycyclic aromatic hydrocarbons (PAHs) in aged soil samples from various contaminated sites is influenced by soil characteristics and by PAH physico-chemical properties. The results were evaluated using the multivariate statistical tool, partial least squares projections to latent structures (PLS). The PAH-contaminated soil samples were characterised (by pH, conductivity, organic matter content, oxide content, particle size, specific surface area, and the time elapsed since the contamination events, i.e. age), and subjected to relatively mild, slurry-phase Fenton's reaction conditions. In general, low molecular weight PAHs were degraded to a greater extent than large, highly hydrophobic variants. Anthracene, benzo(a)pyrene, and pyrene were more susceptible to degradation than other, structurally similar, PAHs; an effect attributed to the known susceptibility of these compounds to reactions with hydroxyl radicals. The presence of organic matter and the specific surface area of the soil were clearly negatively correlated with the degradation of bi- and tri-cyclic PAHs, whereas the amount of degraded organic matter correlated positively with the degradation of PAHs with five or six fused rings. This was explained by enhanced availability of the larger PAHs, which were released from the organic matter as it degraded. Our study shows that sorption of PAHs is influenced by a combination of soil characteristics and physico-chemical properties of individual PAHs. Multivariate statistical tools have great potential for assessing the relative importance of these parameters.     

Dielectrophoresis-induced separation of metallic and semiconducting single-wall carbon nanotubes in a continuous flow microfluidic system

The AC dielectrophoresis-induced separation of metallic and semiconducting single-wall carbon nanotubes has been carried out in a continuous flow microfluidic system with isolated electrodes. The separation has been studied for single-wall carbon nanotube aqueous suspensions with ionic (sodium dodecylsulphate) and non-ionic (TritonX-100) surfactants. The efficiency of separation has been determined with the help of resonant Raman spectroscopy using various excitation energies. The prototype microfluidic cell presently shows somewhat inferior separation efficiency with respect to static dielectrophoretic filtering on arrays of microelectrodes but has potential for improvements. Factors influencing the separation efficiency and scaling up of the process are discussed.     

Tocopherols in rose hips (Rosa spp.) during ripening

BACKGROUND: Rose hips are used as a food ingredient and in health products. They are rich in various bioactive compounds such as carotenoids and vitamin C, but data on their vitamin E content (tocopherols and tocotrienols) are limited. In this study, four different species ofRosa were analysed for tocopherol and tocotrienol content during ripening in three different years. RESULTS: Only α‐ and γ‐tocopherol were found in the fleshy parts of the rose hips, and the tocopherol content and vitamin E activity varied depending on date of harvesting, species and year. The amount of vitamin E activity differed between species of Rosa and years, whereas the changes during ripening were relatively small. CONCLUSION: The choice of species must be considered if tocopherol content is to be optimised when rose hips are used as a food ingredient. Copyright © 2012 Society of Chemical Industry     

RFID sensors based on ubiquitous passive 13.56‐MHz RFID tags and complex impedance detection

Passive radio frequency identification (RFID) sensors are attractive in diverse applications where sensor performance is needed at a low cost and when battery‐free operation is critical. We developed a general approach for adapting ubiquitous and cost‐effective passive 13.56‐MHz RFID tags for diverse sensing applications. In developed RFID sensors, the complex impedance of the RFID resonant antenna is measured and correlated to physical, chemical, or biological properties of interest. In contrast to known wireless sensors, developed RFID sensors combine several measured parameters from the resonant sensor antenna with multivariate data analysis and deliver unique capability for multianalyte sensing and rejection of environmental interferences with a single sensor. Theoretical calculations and experiments in an anechoic chamber demonstrate that the developed RFID sensors are immune to common electromagnetic interferences and the sensor/reader system operates within regulated emission levels. Performance of developed RFID sensors is illustrated in measurements of toxic industrial chemicals (TICs) in air with the detection limit (DL) of 80 parts per billion and in a non‐invasive monitoring of milk spoilage. Sensors selectivity is demonstrated in the detection of different vapors with individual sensors. Copyright © 2008 John Wiley & Sons, Ltd.     

Residual stresses in TiN, DLC and MoS2 coated surfaces with regard to their tribological fracture behaviour

Thin hard coatings on components and tools are used increasingly due to the rapid development in deposition techniques, tribological performance and application skills. The residual stresses in a coated surface are crucial for its tribological performance. Compressive residual stresses in PVD deposited TiN and DLC coatings were measured to be in the range of 0.03-4 GPa on steel substrate and 0.1-1.3 GPa on silicon. MoS₂ coatings had tensional stresses in the range of 0.8-1.3 on steel and 0.16 GPa compressive stresses on silicon. The fracture pattern of coatings deposited on steel substrate were analysed both in bend testing and scratch testing. A micro-scale finite element method (FEM) modelling and stress simulation of a 2 μm TiN-coated steel surface was carried out and showed a reduction of the generated tensile buckling stresses in front of the sliding tip when compressive residual stresses of 1 GPa were included in the model. However, this reduction is not similarly observed in the scratch groove behind the tip, possibly due to sliding contact-induced stress relaxation. Scratch and bending tests allowed calculation of the fracture toughness of the three coated surfaces, based on both empirical crack pattern observations and FEM stress calculation, which resulted in highest values for TiN coating followed by MoS₂ and DLC coatings, being K_C = 4-11, about 2, and 1-2 MPa m^1/2, respectively. Higher compressive residual stresses in the coating and higher elastic modulus of the coating correlated to increased fracture toughness of the coated surface.     

High-Temperature Phase Equilibria of Duplex Stainless Steels Assessed with a Novel <Emphasis Type="Italic">In-Situ</Emphasis> Neutron Scattering Approach

Duplex stainless steels are designed to solidify with ferrite as the parent phase, with subsequent austenite formation occurring in the solid state, implying that, thermodynamically, a fully ferritic range should exist at high temperatures. However, computational thermodynamic tools appear currently to overestimate the austenite stability of these systems, and contradictory data exist in the literature. In the present work, the high-temperature phase equilibria of four commercial duplex stainless steel grades, denoted 2304, 2101, 2507, and 3207, with varying alloying levels were assessed by measurements of the austenite-to-ferrite transformation at temperatures approaching 1673 K (1400 °C) using a novel in-situ neutron scattering approach. All grades became fully ferritic at some point during progressive heating. Higher austenite dissolution temperatures were measured for the higher alloyed grades, and for 3207, the temperature range for a single-phase ferritic structure approached zero. The influence of temperatures in the region of austenite dissolution was further evaluated by microstructural characterization using electron backscattered diffraction of isothermally heat-treated and quenched samples. The new experimental data are compared to thermodynamic calculations, and the precision of databases is discussed.     

抑制次同步谐振的TCSC主动阻尼控制

采用同步电压反转(synchronous voltage reversal,SVR)触发控制的可控串联补偿电容(thristor controlled series compensator,TCSC)本身不会诱发系统的次同步谐振(sub- synchronous resonance SSR),而且因为其在次同步频率范围内固有的感性阻抗特性,一直以来工程中都把TCSC作为一种缓解SSR的有效措施。虽然采用SVR触发的TCSC可缓解系统SSR的压力,但其本身却无法主动抑制SSR,该文提出一种TCSC的附加控制--主动阻尼控制,通过调节TCSC的触发,可使系统在危险振荡模式下向机组提供正值的电气阻尼,从而更好地抑制SSR。时域及频域的仿真也验证了该主动阻尼控制的有效性。