RF MEMS impedance tuners for 6–24 GHz applications

RF MEMS tuners with wide impedance coverage have been developed for 6–24 GHz noise parameter and load‐pull measurement systems. The tuners are based on triple‐, double‐, and single‐stub topologies loaded with switched MEMS capacitors. Several designs are presented, and they use 10–13 switched MEMS capacitors to produce 1024–8192 (2¹⁰–2¹³) different impedances. The measured impedance coverage agrees well with simulations and it is the widest ever measured impedance coverage from any planar tuner to‐date. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2007.     

Energy diversification in Finland: achievements and potential of renewable energy development

Finland was an early adopter of several alternative energy technologies, particularly in biomass and hydropower energy for many years. The main policy in the Finnish energy and climate sectors is to increase the exploitation of renewable energy sources while reducing CO₂ emissions. Meanwhile, a successful energy policy should achieve three conflicting objectives: clean, cheap, and secure energy. The development of renewables in Finland has lagged that of other EU countries, particularly in fields such as wind power in recent years. This article discusses about the history, current status, and potentials of the major renewable and local energy in order of utilisation in Finland. It is seen that the major contributors to replacing carbon-based fuels are likely to be biomass and wind power, with geothermal and solar energy sources to play a lesser role.     

Showing asymmetries in knowledge creation and learning through proactive vision

Communicating with personnel is difficult if the concept in hand is complex, hard to perceive, has characteristics that are fuzzy in nature and that need a long-term perspective to show the results of them as a real benefit and advantage. Knowledge creation and learning concepts both belong to these kinds of management objects. Both have characteristics that are difficult to manage and lead, and that are difficult to articulate in detail to the organisation. Knowledge creation has long been one of the key concepts in modern management science and research. Learning, however, has not achieved that high a status. Many contemporary scientists like to bring in new constructs to better understand the mechanisms behind knowledge creation and learning; however, measuring these kinds of abstract concepts needs support from theory as well as methodology, so that communication to personnel can be objective and, from a management point view, effective. In this research, we have used Internet-based computer applications to measure current knowledge creation and learning levels, and to gain insight into how members of organisations are willing to show their proactive vision, as well as priorities in knowledge creation and learning concepts, inside their organisation. Practical asymmetries can be shown with test subjects, which are important to understand from a leadership and management point of view. The dataset used for this article contains academic and private organisations.     

Improved adhesion of TiO2‐based multilayer coating on HDPE and characterization of photocatalysis

Multilayered photocatalytic TiO₂‐based coating was prepared by spin coating on a high‐density polyethylene (HDPE) substrate. The multilayered coating consisted of a polyurethane (PU) barrier layer and two layers of TiO₂ nanoparticles bound with PU. The adhesion between the HDPE substrate and protective PU coating was enhanced by oxygen plasma treatment of the substrate. The improved adhesion contributed to the photocatalytic degradation of palmitic acid. Long‐term activity of the photocatalytic coating in degradation of palmitic acid under UV illumination was followed by FTIR‐ATR. The catalytic activity of the coating was maintained in three identical cycles where palmitic acid was added and UV‐irradiated for 6 h. According to FTIR measurements, the palmitic acid was almost completely decomposed after 6 h, but gas chromatography (GC) analysis showed total decomposition to require 12 h UV illumination (∼ 97% of palmitic acid decomposed in 12 h). Study of the degradation of palmitic acid by GC as a function of time indicated that the degradation kinetics was pseudofirst order, and the rate constant obtained was 0.31 h⁻¹. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

A common‐gate common‐source low noise amplifier based RF front end with selective input impedance matching for blocker‐resilient receivers

This paper presents an integrated wideband radio frequency front end with improved blocker resilience achieved through selective voltage attenuation at both input and output nodes of the low noise amplifier (LNA). The architecture differs from traditional LNA architectures where blockers are only attenuated at LNA output node. The proposed dual attenuation is attained by designing a low intrinsic input impedance common‐gate common‐source LNA with capacitive feedback, together with an N‐path filtering load. The capacitive feedback across the LNA ensures that the selective N‐path filtering profile at the LNA output is transferred to the LNA input nodes creating a selective input impedance. Consequently, the achieved front‐end input impedance is low at blocker frequencies and matched to the source impedance at the desired frequencies, creating the desired voltage attenuation for blockers. Further, a detailed theoretical analysis of proposed architecture is presented, which leads to clear design guidelines. Evaluated in a 28‐nm fully depleted silicon‐on‐insulator complementary metal oxide semiconductor (CMOS) process, front end is designed for wideband operation from 0.7 to 2.7 GHz. It consumes 11‐mA current from a 1‐V supply (excluding local oscillator (LO) buffering) and possesses a maximum noise figure of 5.1 dB. The front end demonstrates an out‐of‐band blocker compression point of ?1.5 dBm and out‐of‐band IIP3 of +14 dBm at a 100‐MHz offset from LO frequency. In comparison with a traditional common‐gate common‐source LNA‐based front end with wideband input impedance matching, the proposed front end achieves 3.5‐dB improvement in the blocker compression point at a 100‐MHz offset from LO.     

Density estimation with locally identically distributed data and with locally stationary data

Abstract. We consider multivariate density estimation when the assumptions of identically distributed data or stationary data are relaxed to the assumptions of locally identically distributed data or locally stationary data. We assume that the distribution of the data is changing continuously as function of time. To estimate densities non‐parametrically with these local regularity conditions, we need time localization in addition to the usual space localization. We define a time‐localized kernel estimator that estimates the density non‐parametrically at any given point of time. The consistency of the time‐localized kernel estimator is proved and the rates of convergence of the estimator are derived under conditions on the β‐and α‐mixing coefficients. Both the time‐series setting and spatial setting are covered.     

Lactic acid based poly(ester-urethanes): Use of hydroxyl terminated prepolymer in urethane synthesis

We studied a two step process for lactic acid polymerization: in the first step, the lactic acid is condensation polymerized to a low molecular weight hydroxyl terminated prepolymer and then the molecular weight is raised by joining prepolymer chains together using diisocyanate as the chain extender. The resulting polymer is a thermoplastic poly(ester-urethane). The polymer samples were carefully characterized with ¹³C-NMR, GPC, DSC, and IR. The results indicate that high conversions of lactic acid can be achieved, as well as independent control of the stereostructure, long chain branches, molecular weight average, and molecular weight distribution. Lactic acid is converted into a poly(ester-urethane) with a weight average molecular weight as high as 390,000 g/mol and a glass transition temperature of 53.7°C. The analyzed content of the monomer in the prepolymer is less than 1 mol % and the lactide content 2.4 mol %, while the final poly(ester-urethane) is essentially monomer and lactide free. The mechanical properties of the poly(ester-urethane) are comparable to those of polylactides. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1091–1100, 1997     

Lipid profile,lipid ratios,apolipoproteins, and risk of cardiometabolic multimorbidity in men: The Kuopio Ischaemic Heart Disease Risk Factor Study

The blood level of lipids, apolipoproteins, and lipid ratios are important predictors of some chronic diseases. However, their association with cardiometabolic multimorbidity (CMM) is less known. We evaluated a wide range of lipid profiles and lipid ratios, including low-density lipoprotein-cholesterol (LDL-C), very-low-density lipoprotein-cholesterol (VLDL-C), high-density lipoprotein-cholesterol (HDL-C), and apoA1 and B, as well triglyceride and total cholesterol with risk of incident CMM. In 1728 men aged 52.5 ± 5.2 years from the Kuopio Ischaemic Heart Disease were included in this study. We defined CMM as coexisting of two or more of stroke, type 2 diabetes mellitus (T2D), coronary heart disease (CHD). A Cox proportional hazard regression method was applied to evaluate the risk of CMM against the exposures. During the mean follow-up of 22.4 years, 335 men suffered from CMM conditions. Higher serum triglyceride and VLDL concentrations were associated with a higher risk of coexisting T2D-CHD (HRs 1.99 (95% CI, 1.12–3.53) and HRs 1.79 (95% CI, 1.04–3.11), respectively. Whereas higher HDL was associated with lower incident [HRs 0.49 (95% CI, 0.40–1.00)]. The HRs for coexisting T2D-CHD was 2.02 (95% CI, 1.01–3.07) for total cholesterol/HDL-C, 1.85 (95% CI, 1.04–3.29) for triglyceride/HDL-C, 1.69 (95% CI, 1.01–2.31) for Non-HDL-C/HDL-C, and 1.89 (95% CI, 1.03–2.46) for apoB/apoA1. In contrast, serum LDL-C/apoB ratios were inversely associated with the risk of coexisting T2D-CHD [HRs 0.50 (95% CI, 0.28–0.90)]. No associations were observed between our exposures and other CMM conditions. In conclusion, elevated triglyceride, VLDL-C, total cholesterol/HDL-C, TG/HDL-C, apoB/apoA1 as well as lower LDL-C/apoB were independently associated with the higher risk of T2D-CHD coexistence.