Quantitative Comparison of Bilateral Teleoperation Systems Using μ-Synthesis

This paper presents a quantitative comparison framework for bilateral teleoperation systems (BTSs) that have different dynamic characteristics and sensory configurations for a given task-dependent performance objective (TDPO). mu-synthesis is used to develop the framework since it can efficiently treat systems containing uncertainties and disturbances. The framework consists of: 1) a feasibility test and 2) a comparison methodology using prioritized TDPOs. As the formulation used is based on mu-synthesis, the system, operator, and environment models are represented in the form of linear nominal models with frequency-dependent multiplicative uncertainties. This framework is applied to a BTS including an uncertain human operator and environment in a practical case study. The validity of the proposed quantitative framework is confirmed through experiments. The proposed framework can be used as a tool to design BTSs, especially when there are constraints in designing drive mechanisms and choosing sensory configurations.     

Poly(2‐hydroxyethyl methacrylate) nanocomposites: From a nonionic gel to pH sensitivity

2‐Hydroxyethyl methacrylate (HEMA)‐clay nanocomposites were prepared via in situ free radical polymerization using montmorillonite (MMT) as a crosslinker. The structure and surface morphology of the nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction, and scanning electron microscopy. It was found that exfoliated or highly expanded intercalated nanocomposite structure was obtained. The swelling degree was determined in distilled water and various pH buffered solutions. The highest swelling capacity in distilled water was observed for the nanocomposite sample prepared with the MMT amount of 10 % (w). It was seen that the diffusion mechanism was Fickian type in distilled water and also in various pH‐buffered solutions. It is interesting that the swelling degree of nanocomposites in alkaline pH values increased by the increasing of MMT in the polymer structure. This result supports the possibility of future applications of the novel nanocomposite in systems for the controlled released of drugs. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

How do Virtual Badges Incentivize Voluntary Contributions to Online Communities?

Online communities rely heavily on badges to incentivize users to participate in voluntary activities. We examine the relationship between earned badges/pursued badges and contributions in the Stack Overflow question and answer community. Our main results reveal that different levels of earned and pursued badges increase the amount of subsequent answering activity. In addition, earned gold badges are the most influential in the motivation of users while earned bronze badges are the least impactful. Furthermore, the effect of badges involves positive spillovers from higher levels of earned badges to lower ones. Our findings offer important theoretical and managerial implications for online communities.     

Selecting a Customization Strategy Under Competition: Mass Customization, Targeted Mass Customization, and Product Proliferation

Customization requires not only an implementation of proper manufacturing systems but also a proper strategy regarding when firms should offer customized products and what the nature of customization should be. This paper questions 1)whether customization is better than no customization, and, if so, 2) what kind of customization strategy firms should adopt under competition. We find that customization is not optimal when the cost of soliciting customer preference information is sufficiently high. When competing firms choose to customize, we show that firms target only certain customer segments with customized products. We also find that the optimal customization strategy may require firms to offer only a few discrete product varieties. Despite the concern that customization may initiate price wars because customization reduces product differentiation, we find that customization does not escalate the price competition, because aggressive price competition exacerbates cannibalization. Although customers within the product line of a firm are charged higher prices, we show that on average customers are better off when firms adopt customization. However, unless the customization is quite cheap, when firms choose to customize, we find that firms cannot generate more profits than when firms offer only a single product     

Hydropower for sustainable energy development in Turkey: The small hydropower case of the Eastern Black Sea Region

Turkey is a rich country from the point of variety and potential of renewable energy resources. Hydros, winds, biomass, solar and geothermal are important renewable and environmentally friendly sources for energy in Turkey. Turkey produces large amount of hydropower with a total gross hydropower potential of 433 TW h/yr, which is equal to 13.8% of the total hydropower potential of Europe. Technically useable potential is 216 TW h/yr and economic potential is 140 TW h/yr. The main aim of the present study is to investigate hydropower potential of Turkey and small hydropower plants in Eastern Black Sea Region for sustainable energy development in Turkey. The geography of Turkey especially, Eastern Black Sea Region supports and suitable the development of the small hydro plants to increase the energy generation and utilization of available water sources in Turkey. Besides, the paper deals with hydropower policies to meet ever increasing energy demand for sustainable development of Turkey.     

High-performance liquid chromatography-electrospray ionization mass spectrometry using monolithic capillary columns for proteomic studies

The use of tetrahydrofuran/decanol as porogens for the fabrication of micropellicular poly(styrene/divinylbenzene) monoliths enabled the rapid and highly efficient separation of peptides and proteins by reversed-phase high-performance liquid chromatography (RP-HPLC). In contrast to conventional, granular, porous stationary phases, in which the loading capacity is a function of molecular mass, the loadability of the monoliths both for small peptides and large proteins was within the 0.40.9-pmol range for a 60- x 0.2-mm capillary column. Lower limits of detection obtained by measuring UV-absorbance at 214 nm with a 3-nl capillary detection cell were 500 amol for an octapeptide and 200 amol for ribonuclease A. Upon reduction of the concentration of trifluoroacetic acid in the eluent from the commonly used 0.1-0.2 to 0.05%, the separation system was successfully coupled to electrospray ionization mass spectrometry (ESI-MS) at the cost of only a small decrease in separation efficiency. Detection limits for proteins with ESI-MS were in the lower femtomole range. High-quality mass spectra were extracted from the reconstructed ion chromatograms, from which the masses of both peptides and proteins were deduced at a mass accuracy of 50-150 ppm. The applicability of monolithic column technology in proteomics was demonstrated by the mass fingerprinting of tryptic peptides of bovine catalase and human transferrin and by the analysis of membrane proteins related to the photosystem II antenna complex of higher plants.     

Description of Instantaneous Restriction Space for Multi-DOFs Bilateral Teleoperation Systems Using Position Sensors in Unstructured Environments

This paper investigates a novel position-sensor-based force reflection framework for multi-degree-of-freedom (DOF) bilateral teleoperation systems in unstructured environments. The conventional position-sensor-based force reflection method, which is known as position error feedback, may generate grossly inaccurate force reflection directions during collisions involving the slave manipulator links. The proposed restriction space projection framework calculates the instantaneous restriction space to provide the accurate force reflection, regardless of kinematic dissimilarity (KDS) conditions of bilateral teleoperation systems. Simulation results confirmed the validity of the proposed framework in a KDS bilateral teleoperation system under various constraint conditions.     

Effects of microwave irradiation and chemical fixation on the localization of perisinusoidal cells in rat liver by gold impregnation

Modified gold impregnation is one of the methods that are used in light microscopical demonstration of hepatic perisinusoidal cells. This method has some disadvantages, such as restriction of fixation time to 16 h, which allows limited time for processing the tissues, especially when dealing with a large amount of material, and a long impregnation time (16–24 h). We investigated the effect of prolonged fixation on the staining of sections, to shorten the time needed for gold impregnation by using microwave irradiation. Liver specimens were fixed in Baker's calcium–formalin for different periods of time. After fixation, frozen sections were impregnated in gold chloride solution either at room temperature or in a microwave oven. The staining quality of the sections which had been impregnated in the microwave oven for a much shorter time were equal to or even superior to the ones impregnated at room temperature. Prolonging the fixation time up to 7 days did not affect the staining results by microwave irradiation, whereas satisfactory results were not obtained from sections stained at room temperature and fixed for more than 3 days. We conclude that microwave irradiation can be used to shorten the impregnation time in gold chloride solution and the duration of fixation can be prolonged up to 3 days in the original method and up to 7 days when microwave irradiation is used during impregnation.