Tracking and Vibration Control of Flexible Robots Using Shape Memory Alloys

This paper considers the tracking control problem for flexible robots with active vibration suppression by shape memory alloys (SMAs). With a singular perturbation technique, the flexible modes and joint angles are modeled as fast and slow variables, respectively. The fast subsystem comprising the nonlinear SMA dynamics is obtained in a strict feedback form feasible for the backstepping design. The SMA actuators are configured in redundant pairs for an active suppression of vibrations. For the slow subsystem, asymptotically stable tracking is ensured, while for the fast subsystem, uniform exponential stability is guaranteed. By invoking Tikhonov's theorem, it is shown that the error arising from the nonideal time-scale separation in the singular perturbation model is small. Simulation demonstrates the effectiveness of the proposed control     

Engineering a human bone marrow model: a case study on ex vivo erythropoiesis

Theoretical and practical problems related to the dosimetric data verification for recovery workers at the Chernobyl NPP are considered. The distinctions in definitions epsilon-entropy in paper [1] and delta-entropy in [2] are considered. In a certain measure this distinctions explain distinction in conclusions, made in these papers. Method of dosimetric data collection, used by Institute of Biophysics and its difference from the method of data acquisition, used in national Medical-dosimetric registers is described. Results on determination of a share of participants given for various clean-up worker divisions, contained in pointed delta-shape peaks, received by two various methods, stated in [2] and [6], are compared and their satisfactory conformity with one another is established.     

Online signature verification using a new extreme points warping technique

There are two common methodologies to verify signatures: the functional approach and the parametric approach. In this paper, we propose a new warping technique for the functional approach in signature verification. The commonly used warping technique is dynamic time warping (DTW). It was originally used in speech recognition and has been applied in the field of signature verification with some success since two decades ago. The new warping technique we propose is named as extreme points warping (EPW). It proves to be more adaptive in the field of signature verification than DTW, given the presence of the forgeries. Instead of warping the whole signal as DTW does, EPW warps a set of selected important points. With the use of EPW, the equal error rate is improved by a factor of 1.3 and the computation time is reduced by a factor of 11.     

A case of anaphylactic shock induced by FX60 polysulfone hemodialyzer but not F6‐HPS polysulfone hemodialyzer

A 75‐year‐old woman was admitted for dyspnea and fever. She underwent emergent dialysis smoothly under F6‐HPS polysulfone hemodialyzer. With two subsequent hemodialysis sessions, severe anaphylactic reaction with cardiopulmonary resuscitation occurred under FX60 polysulfone dialyzer. Further dialysis sessions by F6‐HPS polysulfone dialyzer were uneventful. This rare case demonstrated that dialyzer reaction may be markedly different even with the same material and the same manufacturer.     

Extraction of phytochemicals using hydrotropic solvents

Every plant synthesizes phytochemicals with different properties to supply a pool of molecules for food, chemical and pharmaceutical applications. Concurrent with “green technology” development, use of green solvents to extract phytochemicals instead of conventional non-eco-friendly solvents is crucial. Hydrotrope is a one of the green solvents that enhances solubility of poorly water-soluble or hydrophobic compounds in aqueous solutions. This article critically reviews the extraction of phytochemicals using various hydrotropic solvents. Hydrotropy mechanisms, factors influencing extraction and recovery methods of phytochemicals were also evaluated in this review.     

A dynamic‐biasing 4× charge pump based on exponential topology

A 4× charge pump using exponential topology is proposed and implemented. Comparing to the conventional implementations, the proposed circuit suppresses the reverse current effectively without using different threshold‐voltage transistors and additional capacitors. Also, the body effect found in the charge transfer switches is eliminated. The proposed charge pump is analyzed with the state‐space method and fabricated using 0.35 µm complementary metal–oxide–semiconductor process. Results show that the output voltages close to the ideal one, and a maximum power efficiency of 95% was recorded. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis and Physicochemical Properties of Low Viscosity 2-Ethylhexyl Alkyl Ethers Made from Palm-Based Esters as Potential Biolubricant

A series of 2-ethylhexyl alkyl ethers (EHAE) are synthesized from palm-based esters via a one-step reaction under mild reaction conditions for potential usage as biolubricant. In this work, 2-ethylhexyl esters with varying fatty acid chain lengths are reacted with 1,1,3,3-tetramethyldisiloxane (TMDS), catalyzed by indium bromide (InBr₃) at 40 °C to afford EHAE with lauryl, palmityl, stearyl, and oleyl alkyl chain with 55–68% isolated yield. These compounds are characterized using Fourier-transform infrared (FTIR) and NMR spectroscopic methods and are evaluated for their viscosity, thermal, cold-flow, oxidative, and anti-wear properties. The synthesized EHAEs demonstrate low viscosity (1.65–2.55 cSt at 100 °C) with excellent viscosity indices (130–182). These EHAEs show comparable wear scar diameter (0.6–1.0 mm) in comparison with commercial mineral oil base stock (group I SN150) in the four-ball wear test. Thermal-oxidative investigation of the EHAE reveals that the thermal degradation temperatures are in the range of 200–250 °C and oxidation onset temperatures are between 165 and 184 °C. Among the EHAEs, 2-ethylhexyl lauryl ether with the shortest alkyl chain has the lowest pour point of ?27 °C. The physicochemical properties of synthesized EHAEs indicate that they are potential as biolubricant base stocks. Practical Applications : The EHAEs produced from this work exhibit promising physicochemical and lubricity properties, which offer great potential to be used as lubricant base stock especially for internal engine oil application.     

Preparation of a photoresponsive molecularly imprinted polymer containing fluorine-substituted azobenzene chromophores

The primary objective of this work is to explore the photoresponsive molecular recognition directed by fluorine-fluorine interaction. A new kind of fluorine-substituted photoresponsive functional monomer, (4-methacryloyloxy) nonafluoroazobenzene (MANFAB), was designed and synthesized, and a photoresponsive molecularly imprinted polymer containing a fluorine-substituted azobenzene chromophore (MIPF) was then fabricated using MANFAB as the monomer and 2,3,4,5,7,8,9,10-octafluorophenazine (PAF) as the model template. The photoisomerization process of MIPF materials is reversible. The release and uptake of PAF from toluene is photoregulated by alternate irradiation at 315 nm and 440 nm, indicating that photoresponsive molecular recognition directed by fluorine-fluorine interaction is possible. The binding strength of the imprinted receptor sites in MIPF for PAF is 4.67 × 10⁴ M⁻¹. The density of receptor sites in the MIPF material is 1.26 μmol/g-MIPF.