bluuebunny/crossref_metadata_2025 huggingface dataset:
TEM Study of Ni-Mn-Co-In Ferromagnetic Shape Memory Alloys
Authors: Prusik Krystian , Bałdys Katarzyna , Stróż Danuta
Published: March 2012

Ferromagnetic shape memory alloys (FSMA) are relatively new smart materials group. Recently, new FSMA from NiMnX (X=Sb, Sn, In, Co+In) systems are considered as alternative to the well known NiMnGa alloys. Four alloys of the following compositions: Ni43Mn35Co4In18, Ni41Mn35Co4In20, Ni42Mn35Co5In18, Ni40Mn35Co5In20 were studied in order to determine microstructure, phase composition and martensitic transformation temperatures versus their chemical composition. Structure of the alloys was studied by optical and transmission electron microscopy (TEM). All of the studied alloys showed macrostructure consisting of radially oriented columnar grains in the direction perpendicular to the casting axis. The structure of the phases occurred in the studied alloys depended on the cobalt and indium content. For the alloys containing 20 at. % of In at room temperature only L21 parent phase was observed whereas for those containing 18 at. % of In either single phase 14M modulated martensite or mixture of 14M martensite and L21 parent phase were seen. DSC measurements showed in studied alloys single-state martensitic transformation. Decrease In content of 2 at.% caused about 80°C fall of martensitic transformation temperatures. Curie temperature Tc increases of 20°C with 1 at% rise of the cobalt content.
Tin Pest and Tin Oxidation on Tin-Rich Lead-Free Alloys Investigated by Electron Microscopy Methods
Authors: Czerwiński Andrzej , Skwarek Agata , Płuska Mariusz , Ratajczak Jacek , Witek Krzysztof
Published: March 2012

Soldering of joints in electronic circuits is performed in all branches of electronic industry. At temperatures below 13.2°C, an allotropic transformation of white β-tin into gray α-tin called tin pest may occur, leading to the degradation of mechanical properties or even a total disintegration of the alloy. Presence of some chemical elements in the alloy can inhibit the transformation, while other can promote it, e.g. a significant Pb addition prevents the transformation. However, the Restriction of Hazardous Substances Directive adopted by the European Union since 2006, limits Pb amount to 0.1 wt.%, leading to tin pest phenomenon in tin rich materials. The energy dispersive X-ray spectroscopy (EDXS) in scanning electron microscope was performed on samples of tin-rich lead-free alloys subjected to accelerated low temperature stress and after months of storage at -18 °C showed the tin pest occurrence. Much higher oxygen content in EDXS spectrum was revealed at old regions of transformed α-tin than at new α-tin and non-transformed β-tin regions. The tin pest oxidation is much accelerated in comparison to β-tin and can finally lead to the consuming of the whole tin in deteriorated places by the tin oxide.
The Degradation of Microstructure of AlCu4Ni2Mg Aluminium Alloy after Prolonged Annealing at Elevated Temperature
Authors: Wierzbińska Małgorzata , Sieniawski Jan
Published: March 2012

The influence of long term annealing on microstructure of Al-Cu4-Ni2-Mg aluminum alloy was investigated. The castings were subjected to T6 heat treatment followed by annealing at 523 K and 623 K for 100, 150, 300, 500 and 750 hours. The soaking time and temperature was adjusted by corresponding to real service conditions of the elements of an aircraft and motor engines from investigated alloys. Microstructural examination of the alloy was carried out with optical microscope, as well as scaning and transmissiom electron microscopes. The result of microscopic analysis showed that applied heat treatment caused an increasing in the particles of hardening (θ’-Al2Cu) phase size. The significant growth of the length and changing the value of shape factor of hardening phase precipitations was observed. The phenomenon of the increase in size and change in shape of precipitations of hardening phases continually change with the prolonged holding time at high temperature. The microstructure degradation is connected to a decrease of mechanical properties of alloy, confirmed by the result of tensile tests.
TEM Investigation of Interfaces Formed between SaffilTM Fibers and AA6061 and En Ac 44200 Aluminium Alloys
Authors: Pomorska Malgorzata , Kaczmar Jacek , Morgiel Jerzy , Naplocha Krzysztof
Published: March 2012

The metal matrix composites (MMC) were produced by force infiltration of preforms containing up to 10 vol % of Saffil fibers with AA6061 and EN AC 44200 aluminium alloys. The fibers were stabilized inside preform by dipping in liquid glass and heat treated at 800oC/2 hours. It allowed both to coat fibers with a thin layer of silica and bond fibers with amorphous silica bridges producing self supporting porous structure. The microstructure observations were performed using Tecnai FEG (200kV) transmission electron microscope. The performed investigations showed that infiltrating preform with AA6061 alloy with ~1 wt. % Mg caused reaction of silica with liquid metal substituting the former with porous amorphous Al2O3. A presence of MgO at the interfaces with aluminium matrix was noted. The infiltration with low magnesium EN AC 44200 (Mg <0.6 wt.%) alloy helped to produce composite with the silica bridges between fibers practically intact.
Three-Dimensional Visualization and Metrology of Nanoparticles in Inconel 718 by Electron Tomography
Authors: Kulawik Krzysztof , Kruk Adam , Dubiel Beata , Czyrska-Filemonowicz Aleksandra
Published: March 2012

In the present work a quantitative analysis of γ' and γ" phase nanoparticles in Inconel 718 was performed using two methods of electron tomography, namely EFTEM and FIB tomography. 3D visualisation showed that γ' particles are spherical, while γ" precipitates are disc-shaped. The values of mean size of γ' and γ" phase particles, determined by both electron tomography methods applied, are in good agreement.
Phase Identification in Nickel-Based Superalloys Using EBSD/SEM and Electron Diffraction in STEM
Authors: Chmiela Bartosz , Sozańska Maria , Rodak Kinga
Published: March 2012

Aero engine turbine blades made of nickel-based superalloys are critical components in flight safety. Therefore, it is very important to make sure that the chemical composition, phase composition and microstructure are suitable. However, due to their chemical compositions, superalloys are prone to many transformations and the formation of deleterious phases, which deteriorate the mechanical properties. Hence, investigations concerning the structural stability and phase identification—especially topologically close-packed phases (TCP)—are necessary. Because the volume fractions of these phases are generally small, phase identification should be performed by nanodiffraction techniques in a scanning transmission electron microscope (STEM) and electron backscatter diffraction in a scanning electron microscope (EBSD/SEM). These methods complement each other, but each of them is characterized by different difficulties and limitations. In this paper we present the possibilities and limitations of phase identification in single crystal CMSX-4 superalloy after long thermal exposure.
Study of Oxides Formed in HfO2/Si Structure for High-k Dielectric Applications
Authors: Łaszcz Adam , Czerwiński Andrzej , Ratajczak Jacek , Taube Andrzej , Gierałtowska Sylwia , Piotrowska Ania , Kątcki Jerzy
Published: March 2012

Transmission electron microscopy (TEM) techniques were used for characterization of annealing (400, 600 and 800 °C) influence on the structural properties of the HfO2 film (45 nm thick) deposited on Si substrate. Such structures are considered as high-k dielectric materials for application in novel semiconductor devices. The studies showed that independently of the annealing temperature a very thin and flat amorphous layer is formed between HfO2 layer and Si substrate. This result was also found in the non-annealed sample. EDXS examination confirmed that the stoichiometry for the hafnium oxide layer in each sample corresponds to 1:2 for Hf:O (i.e. to HfO2). TEM images revealed differences in the microstructure of HfO2 layers in annealed samples, however the layers have similar thickness and interface roughness in all studied samples.
Ni-Based Ohmic Contacts to Silicon Carbide Examined by Electron Microscopy
Authors: Wzorek Marek , Czerwiński Andrzej , Kuchuk Andrian V. , Ratajczak Jacek , Piotrowska Ania , Kątcki Jerzy
Published: March 2012

Ni/Si multilayer contact structures to 4H-SiC after subsequent annealing steps are investigated with electron microscopy methods. After high temperature annealing step, specific defects in the contact structures are observed. The influence of phase transformations during annealings on the morphology on the contacts is discussed and the explanation of formation mechanism of voids within contact layer is proposed.
Crystallization and Microstructure of Co0.75Ni0.25Si2 Solid Solution
Authors: Gurdziel Wojciech , Wokulski Zygmunt , Dercz Grzegorz , Krawczyk Jacek
Published: March 2012

The microstructure of Co0.75Ni0.25Si2solid solution, obtained by two different techniques was studied. The solidification processes were conducted using Bridgman and Czochralski methods. The processes were conducted under atmospheric pressure and in the helium atmosphere. Various pulling down (Bridgman method) and pulling up (Czochralski method) rates were applied for ingots and boules preparation. The obtained Co0.75Ni0.25Si2ingots and boules were subjected to the metallographic observations and chemical microanalysis, mainly used Scanning Electron Microscopy techniques. They were studied using X-ray phase analysis too. Comparing the investigation results it was found that the ingots obtained by the Bridgman method and boules obtained by the Czochralski method were single crystalline. The boules, obtained using the Czochralski method, possess better structural quality than ingots obtained by the Bridgman method.
Crystallographic Aspects of Deformation and Recrystallization in ECAP-Processed AA3104 Aluminium Alloy
Authors: Paul Henryk , Baudin Thierry , Tarasek Anna , Brisset François
Published: March 2012

The objective of this study was to determine the effect of ECAP-processing on the texture and the microstructure development of the deformed and recrystallized states. The commercial purity AA3104 aluminum alloy was deformed via route A up to 7 passes and then annealed to obtain the state of partial recrystallization. The shear bands formation and the texture transformation in annealing were investigated with the use of high resolution transmission and scanning electron microscopes equipped with the facilitates for the local orientation measurements. It was found that the instability of the layered structure of the flat grains within some narrow areas led to the formation of the kink-type bands, which were precursors of the shear bands. The orientations of the new grains occurring in the recrystallized samples were not random, i.e. only specific groups of orientations were observed. In most of the observed cases, the growth of the recrystallized grains led to nearly homogeneous equiaxed grains of a similar size.
l-Tryptophan–Kynurenine Pathway Metabolites Regulate Type I IFNs of Acute Viral Myocarditis in Mice
Authors: Hoshi Masato , Matsumoto Keishi , Ito Hiroyasu , Ohtaki Hirofumi , Arioka Yuko , Osawa Yosuke , Yamamoto Yasuko , Matsunami Hidetoshi , Hara Akira , Seishima Mitsuru , Saito Kuniaki
Published: March 2012

The activity of IDO that catalyzes the degradation of tryptophan (Trp) into kynurenine (Kyn) increases after diseases caused by different infectious agents. Previously, we demonstrated that IDO has an important immunomodulatory function in immune-related diseases. However, the pathophysiological role of IDO following acute viral infection is not fully understood. To investigate the role of IDO in the l-Trp–Kyn pathway during acute viral myocarditis, mice were infected with encephalomyocarditis virus, which induces acute myocarditis. We used IDO-deficient (IDO−/−) mice and mice treated with 1-methyl-d,l-Trp (1-MT), an inhibitor of IDO, to study the importance of Trp–Kyn pathway metabolites. Postinfection with encephalomyocarditis virus infection, the serum levels of Kyn increased, whereas those of Trp decreased, and IDO activity increased in the spleen and heart. The survival rate of IDO−/− or 1-MT–treated mice was significantly greater than that of IDO+/+ mice. Indeed, the viral load was suppressed in the IDO−/− or 1-MT–treated mice. Furthermore, the levels of type I IFNs in IDO−/− mice and IDO−/− bone marrow-transplanted IDO+/+ mice were significantly higher than those in IDO+/+ mice, and treatment of IDO−/− mice with Kyn metabolites eliminated the effects of IDO−/− on the improved survival rates. These results suggest that IDO has an important role in acute viral myocarditis. Specifically, IDO increases the accumulation of Kyn pathway metabolites, which suppress type I IFNs production and enhance viral replication. We concluded that inhibition of the Trp–Kyn pathway ameliorates acute viral myocarditis.
Antigen-Independent Induction of Tim-3 Expression on Human T Cells by the Common γ-Chain Cytokines IL-2, IL-7, IL-15, and IL-21 Is Associated with Proliferation and Is Dependent on the Phosphoinositide 3-Kinase Pathway
Authors: Mujib Shariq , Jones R. Brad , Lo Calvin , Aidarus Nasra , Clayton Kiera , Sakhdari Ali , Benko Erika , Kovacs Colin , Ostrowski Mario A.
Published: March 2012

T cell Ig mucin domain-containing molecule 3 (Tim-3) is a glycoprotein found on the surface of a subset of CD8+ and Th1 CD4+ T cells. Elevated expression of Tim-3 on virus-specific T cells during chronic viral infections, such as HIV-1, hepatitis B virus, and hepatitis C virus, positively correlates with viral load. Tim-3+ cytotoxic T cells are dysfunctional and are unable to secrete effector cytokines, such as IFN-γ and TNF-α. In this study, we examined potential inducers of Tim-3 on primary human T cells. Direct HIV-1 infection of CD4+ T cells, or LPS, found to be elevated in HIV-1 infection, did not induce Tim-3 on T cells. Tim-3 was induced by the common γ-chain (γc) cytokines IL-2, IL-7, IL-15, and IL-21 but not IL-4, in an Ag-independent manner and was upregulated on primary T cells in response to TCR/CD28 costimulation, as well as γc cytokine stimulation with successive divisions. γc cytokine-induced Tim-3 was found on naive, effector, and memory subsets of T cells. Tim-3+ primary T cells were more prone to apoptosis, particularly upon treatment with galectin-9, a Tim-3 ligand, after cytokine withdrawal. The upregulation of Tim-3 could be blocked by the addition of a PI3K inhibitor, LY 294002. Thus, Tim-3 can be induced via TCR/CD28 costimulation and/or γc cytokines, likely through the PI3K pathway.
p110δ Phosphoinositide 3-Kinase Represses IgE Switch by Potentiating BCL6 Expression
Authors: Zhang Ting-ting , Makondo Kennedy J. , Marshall Aaron J.
Published: March 2012

PI3Ks are key signaling enzymes required for triggering many immunological functions. In B lymphocytes, PI3K signaling is required for Ag-induced proliferation and robust production of most Ab isotypes. Paradoxically, PI3K was found to have a negatively regulatory function regarding Ab class switch recombination, and blockade of PI3K can strongly potentiate IgE switch. In this article, we explore the mechanisms of this unexpected negative regulatory function of PI3K regarding IgE. We demonstrate that p110δ PI3K selectively regulates IgE switch in a B cell-intrinsic manner by controlling germline transcription of the IgE promoter (εGLT). Although p110δ can regulate transcription of activation-induced cytidine deaminase via Akt, repression of εGLT and IgE switch is not dependent on Akt signaling. Inhibition of p110δ, but not Akt, leads to reduced expression of transcriptional repressor B cell lymphoma 6 (BCL6) and concomitant upregulation of εGLT and other BCL6-target genes. p110δ inhibitor treatment strikingly alters the balance between BCL6 and IRF4 (a transcription factor that antagonizes BCL6), leading to increased IRF4 and decreased BCL6 expression levels in germinal center B cells. Ectopic expression of BCL6 can partially overcome the elevated εGLTs and potentiated IgE switching in p110δ-inhibited B cells. To our knowledge, these results provide the first evidence that p110δ PI3K signaling regulates BCL6 expression and indicate that PI3K promotes the germinal center B cell program and selectively represses IgE switch by maintaining sufficient levels of BCL6.
APPROACHING THE TARGET: THE PATH TOWARDS AN EFFECTIVE MALARIA VACCINE
Authors: García-Basteiro Alberto L. , Bassat Quique , Alonso Pedro L.
Published: March 2012

Eliciting an effective malaria vaccine has been the goal of the scientific community for many years. A malaria vaccine, added to existing tools and strategies, would further prevent and decrease the unacceptable malaria morbidity and mortality burden. Great progress has been made over the last decade, with some vaccine candidates in the clinical phases of development. The RTS,S malaria vaccine candidate, based on a recombinant P. falciparum protein, is the most advanced of such candidates, currently undergoing a large phase III trial. RTS,S has consistently shown an efficacy of around 50% against the first clinical episode of malaria, with protection in some cases extending up to 4 years of duration. Thus, it is hoped that this candidate vaccine will eventually become the first licensed malaria vaccine. This first vaccine against a human parasite is a groundbreaking achievement, but improved malaria vaccines conferring higher protection will be needed if the aspiration of malaria eradication is to be achieved
The effect of long-term fertilization on soil water storage and water deficit in the Black Soil Zone in northeast China
Authors: Zou Wenxiu , Si Bingcheng , Han Xiaozeng , Jiang Heng
Published: March 2012

Zou, W., Si, B., Han, X. and Jiang, H. 2012. The effect of long-term fertilization on soil water storage and water deficit in the Black Soil Zone in northeast China. Can. J. Soil Sci. 92: 439–448. The Black Soil Zone in northeast China is one of the most important areas of agricultural production in China and plays a crucial role in food supply. However, further improvement in crop yield hinges on effective management of soil water. There is a poor understanding of how different fertilization methods affect crop water use efficiency. The objective of this study was to examine the effect of different fertilization methods on soil water storage and deficit in Black soils. A long-term experiment was conducted at the National Field Research Station of Agro-ecosystems, at Hailun County, Heilongjiang province in northeastern China from 1999 to 2008. Three fertilizer treatments including no fertilizer (CK), inorganic fertilizer (NP) and inorganic fertilizer plus organic material (NPM) were tested. The results showed that soil water storage decreased in the order CK, NP, and NPM during the growing season and the differences in soil water storage in the active root zone (0–70 cm) and below the active root zone (70–130 cm) and soil water deficit were statistically significant among the three treatments. Due to the uneven temporal distribution of rainfall and crop water uptake, soil water content was very dynamic in all three treatments: The low soil water storage and resulting soil water deficit (defined as the monthly difference between potential evapotranspiration and soil available water storage) within the 0- to 70-cm soil profile were found in both June and July. Further, soil receiving NPM was more likely to have a soil water deficit, but less likely to have excessive water. A lower risk of excess water may result in deeper root penetration and increased water use at greater depth, and thus the water deficit under the NPM treatment may not be the limiting factor for crop production. Therefore, NPM seems a viable management practice for improving crop yields in the Black Soil Zone in northeast China, possibly due to higher soil organic carbon and nutrient supply and lower probability of excess water.
Response to water stress of soil enzymes and root exudates from drought and non-drought tolerant corn hybrids at different growth stages
Authors: Song Fengbin , Han Xiying , Zhu Xiancan , Herbert Stephen J.
Published: March 2012

Song, F., Han, X., Zhu, X. and Herbert, S. J. 2012. Response to water stress of soil enzymes and root exudates from drought and non-drought tolerant corn hybrids at different growth stages. Can. J. Soil Sci 92: 501–507. Drought tolerant corn hybrids (Zea mays L.) are an excellent model to evaluate the effect of water stress on rhizosphere functions. The purpose of this study was to investigate the influences of water stress on soil pH, enzyme activities, and root exudates from corn. Two corn hybrids, Baidan 9 (drought tolerant) and Baidan 31 (non-drought tolerant) were grown in soil-filled pots for pH and enzyme assays and in hydroponics culture for root exudate analysis. Water stress was imposed at four growth stages: seedling, elongation, tasseling and grain-filling stages. Soil pH was lower in the rhizosphere than bulk soil, but was not affected by water deficiency. Water stress increased protease activity at the seedling stage, but reduced its activities at other stages compared to the control. A significant positive correlation was observed between pH and alkaline phosphatase activity under water stress. Compared to Baidan 31, the rhizosphere of drought-tolerant Baidan 9 had greater protease and catalase activities at all growth stages, greater alkaline phosphatase, lower acid phosphatase and greater invertase activities at elongation, tasseling and filling stages. Osmotic stress increased the organic acid concentration (malic, lactic, acetic, succinic, citric and maleic acids) in root exudates of Baidan 9 and Baidan 31; as well there was a greater fumaric acid concentration in Baidan 31 under osmotic stress than without stress. The increased soil enzyme activities and organic acids exuded from the rhizosphere of plants under water stress might contribute to drought tolerance in corn hybrids.
Gross Motor Activity and Attention in Three Adults With Brain Injury
Authors: Shimelman Ayala , Hinojosa Jim
Published: March 2012

Objective. In this single-subject study, we evaluated the short-term effects of gross motor activity on the attention behavior of three adults with brain injury. Additionally, observation data were collected on each subject’s performance.

Method. The effects of gross motor activity on the subjects’ attention behavior was measured by performance on visual letter cancellation tasks. The three subjects with brain injury were a 59-year-old woman, a 52-year-old man, and a 26-year-old woman. Data for each subject were graphed and visually analyzed. Observation data for each subject also were examined.

Results. The results did not indicate meaningful differences in the subjects’ performance of letter cancellation tasks after gross motor activity. However, positive changes in scanning and checking behaviors were noted.

Conclusion. This study did not demonstrate improvement in attention behavior after gross motor activity according to the measures used. However, the study supports that observations can help to identify important factors that may influence treatment outcomes. Further study is needed to determine the nature of the relationship between gross motor activity and attention.
Evaluation of Potential Involvement of two MicroRNAs (hsa-miR-590-5p and hsa-miR-497) in Differentiation of Human Cardiac Stem Cells to Cardiomyocytes
Authors: Tousi Seyedeh Samaneh Ekhteraei , B Soltani , M Soleimani , M Sadeghizadeh
Published: March 2012

Objectives

In heart as an organ with low renewal capacity, the processes regulating the differentiation of human cardiac stem cells (hCSCs) are crucial for cardiac diseases therapy. Recent studies have shown that microRNAs (miRNAs) play important roles during heart development. In this research, the expression profile of a few candidate miRNAs was studied in serial differentiation stages of the hCSCs to cardiomyocytes (CM).

Methods

The hCSCs (c-Kit+ progenitor cells) were prepared from Royan Stem Cell Bank (RSCB), cultured and differentiated into CM (Figure 1). The differentiation to CM was confirmed by ICC (Immunocytochemistry) test for cardiac troponinT and real-time PCR for some early cardiac marker and sarcomeric genes. The expression profiles of hsa-miR-590-5p, hsa-miR-497, hsa-miR-125a-5p and hsa-miR-133b were analyzed during the processes of differentiation.

Results

Here for the first time in our knowledge, we showed that in contrast to other upper mentioned candidate miRNAs, hsa-miR-590-5p and hsa-miR-497 are differentially expressed in accordance to the differential stages of hCSCs. The expression levels of these two candidates at the early stages of the CM differentiation were about 5 fold higher than the late stages (P-value<0.05, Figure 2).

Conclusions

All together, our data from four interesting miRNAs award us into the regulatory networks of related genes that are involved in CM differentiation of hCSCs.
Activity of Cuban Plants Extracts againstLeishmania amazonensis
Authors: García Marley , Monzote Lianet , Scull Ramón , Herrera Pedro
Published: March 2012

Natural products have long been providing important drug leads for infectious diseases. Leishmaniasis is a major health problem worldwide that affects millions of people especially in the developing nations. There is no immunoprophylaxis (vaccination) available forLeishmaniainfections, and conventional treatments are unsatisfactory; therefore, antileishmanial drugs are urgently needed. In this work, 48 alcoholic extracts from 46 Cuban plants were evaluated by anin vitrobioassay againstLeishmania amazonensis. Furthermore, their toxicity was assayed against murine macrophage. The three most potent extracts against the amastigote stage ofLeishmania amazonensiswere fromHura crepitans, Bambusa vulgaris, andSimarouba glauca.
Resectable Pediatric Nonrhabdomyosarcoma Soft Tissue Sarcoma: Which Patients Benefit from Adjuvant Radiation Therapy and How Much?
Authors: Million Lynn , Donaldson Sarah S.
Published: March 2012

It remains unclear which children and adolescents with resected nonrhabdomyosarcoma soft tissue sarcoma (NRSTS) benefit from radiation therapy, as well as the optimal dose, volume, and timing of radiotherapy when used with primary surgical resection. This paper reviews the sparse literature from clinical trials and retrospective studies of resected pediatric NRSTS to discern local recurrence rates in relationship to the use of radiation therapy.
The Effect of Waste Fodder Potato Proteins on the Mechanical Properties of Carboxylated Acrylonitrile-Butadiene Rubber
Authors: Prochoń Mirosława , Przepiórkowska Anita , Tshela Ntumba Yves-Herve
Published: March 2012

The current investigation treats about the influence of waste fodder potato proteins (WFPP) recovered from the starch industry on the mechanical-properties of carboxylated acrylonitrile-butadiene rubber (XNBR). WFPP were characterized and used as a filler of the above mentioned XNBR rubber without or after blending with zinc oxide. The obtained rubber compounds were cured, and mechanical properties such as tensile strength, hardness, and cross-linking density were investigated. It was found that the introduction of WFPP previously blended with zinc oxide into rubber compound increases the cross-linking density of the obtained composites, compared with the vulcanizate without protein, which in turn increases the mechanical properties of the obtained vulcanizates. That occurs thanks to the formation of ion nodes, as testified by equilibrium swelling. The introduction of WFPP into the elastomer matrix also increases the susceptibility of the elastomer to biodecomposition.
Mobile Robot Navigation Based on Q-Learning Technique
Authors: Khriji Lazhar , Touati Farid , Benhmed Kamel , Al-Yahmedi Amur
Published: March 2012

This paper shows how Q-learning approach can be used in a successful way to deal with the problem of mobile robot navigation. In real situations where a large number of obstacles are involved, normal Q-learning approach would encounter two major problems due to excessively large state space. First, learning the Q-values in tabular form may be infeasible because of the excessive amount of memory needed to store the table. Second, rewards in the state space may be so sparse that with random exploration they will only be discovered extremely slowly. In this paper, we propose a navigation approach for mobile robot, in which the prior knowledge is used within Q-learning. We address the issue of individual behavior design using fuzzy logic. The strategy of behaviors based navigation reduces the complexity of the navigation problem by dividing them in small actions easier for design and implementation. The Q-Learning algorithm is applied to coordinate between these behaviors, which make a great reduction in learning convergence times. Simulation and experimental results confirm the convergence to the desired results in terms of saved time and computational resources.
Design of Autonomous Underwater Vehicle
Authors: Hyakudome Tadahiro
Published: March 2012

There are concerns about the impact that global warming will have on our environment, and which will inevitably result in expanding deserts and rising water levels. While a lot of underwater vehicles are utilized, AUVs (Autonomous Underwater Vehicle) were considered and chosen, as the most suitable tool for conduction survey concerning these global environmental problems. AUVs can comprehensive survey because the vehicle does not have to be connected to the support vessel by tether cable. When such underwater vehicles are made, it is necessary to consider about the following things. 1) Seawater and Water Pressure Environment, 2) Sink, 3) There are no Gas or Battery Charge Stations, 4) Global Positioning System cannot use, 5) Radio waves cannot use. In the paper, outline of above and how deal about it are explained.
Hybrid Control of Long-Endurance Aerial Robotic Vehicles for Wireless Sensor Networks
Authors: Lee Deok-Jin , Andersson Klas
Published: March 2012

This paper presents an effective hybrid control approach for building stable wireless sensor networks between heterogeneous unmanned vehicles using long-endurance aerial robotic vehicles. For optimal deployment of the aerial vehicles in communication networks, a gradient climbing based self-estimating control algorithm is utilized to locate the aerial platforms to maintain maximum communication throughputs between distributed multiple nodes. The autonomous aerial robots, which function as communication relay nodes, extract and harvest thermal energy from the atmospheric environment to improve their flight endurance within specified communication coverage areas. The rapidly-deployable sensor networks with the high-endurance aerial vehicles can be used for various application areas including environment monitoring, surveillance, tracking, and decision-making support. Flight test and simulation studies are conducted to evaluate the effectiveness of the proposed hybrid control technique for robust communication networks.
Explicit Dynamic Formulation for n-R Planar Manipulators with Frictional Interaction between End-Effecter and Environment
Authors: Noorani SMRS. , Ghanbari Ahmad
Published: March 2012

This paper includes modeling and dynamic analysis of the planar manipulators which consist of n revolute joints and its end-effecter may possess a frictional contact with an arbitrary surface. The dynamic analysis has been done by using the Lagrangian method. The main contribution of this work is presenting the equations of motion of the system in an explicit and straightforward manner. To this end, the absolute angles of the links are chosen as the generalized coordinates to constitute the Lagrangian, and by this way the Coriolis acceleration terms included the product of the joint velocities, will be hidden in structure of the equations of motion. It is very interested in the simplified results that show a clear conformity with the interpretations of the Euler's equation of motion of the rigid body. In following, the results are applied to a case study model to explain the deriving the equations of motion by our formulation. An inchworm robot included an articulated mechanism is considered to this end.
Development of Educational System with the Android Robot SAYA and Evaluation
Authors: Hashimoto Takuya , Kato Naoki , Kobayashi Hiroshi
Published: March 2012

This chapter describes an educational system with a tele-operated android robot, named SAYA, that can express human-like facial expressions and perform some communicative functions with its head and eye movements, and it is utilized as a role of a teacher. Two kinds of field experiments were conducted to investigate effectiveness of this educational system in actual educational fields. An experiment was conducted at both an elementary school and a university to estimate age-dependent differences of its effectiveness. The other experiment was carried out to verify whether children's interest, motivation, and concentration to the class, and science and technologies were enhanced.
Stable Formation Control of Multi-Robot System with Communication Delay
Authors: Jiang Limei , Zhang Rubo
Published: March 2012

In this paper, a distributed formation control algorithm with delayed information exchange is discussed. The algorithm, which is derived from the flocking behaviour of birds and consensus theory, enables robots to move in formation at a desired velocity. After a series of orthogonal transformations to the original formation system, the upper bound tolerable delay is obtained by using matrix theory and the Nyquist criterion. According to the results, the upper bound tolerable delay depends on the control parameters and eigenvalues of the Laplacian matrix. Therefore, the effect of the parameters on the maximum tolerable delay is analysed, obtaining the following conclusions: the upper bound tolerable delay is proportional to the parameters associated with the velocity, inversely proportional to the parameters associated with the position, and inversely proportional to the difference between the eigenvalue of Laplacian matrix and 1. The simulation results of a four-robot formation system with different communication delays verify the effectiveness of the formation control algorithm and the correctness of the theoretical analysis.
A Methodology for the Design of Robotic Hands with Multiple Fingers
Authors: Puig Jorge Eduardo Parada , Rodriguez Nestor Eduardo Nava , Ceccarelli Marco
Published: March 2012

This paper presents a methodology that has been applied for a design process of anthropomorphic hands with multiple fingers. Biomechanical characteristics of human hand have been analysed so that ergonomic and anthropometric aspects have been used as fundamental references for obtaining grasping mechanisms. A kinematic analysis has been proposed to define the requirements for designing grasping functions. Selection of materials and actuators has been discussed too. This topic has been based on previous experiences with prototypes that have been developed at the Laboratory of Robotics and Mechatronics (LARM) of the University of Cassino. An example of the application of the proposed method has been presented for the design of a first prototype of LARM Hand.
Car-Like Mobile Robot Oriented Positioning by Fuzzy Controllers
Authors: Ouadah Noureddine , Ourak Lamine , Boudjema Farès
Published: March 2012

In this paper, fuzzy logic controllers (FLC) are used to implement an efficient and accurate positioning of an autonomous car-like mobile robot, respecting final orientation. To accomplish this task, called “Oriented Positioning”, two FLC have been developed: robot positioning controller (RPC) and robot following controller (RFC). Computer simulation results illustrate the effectiveness of the proposed technique. Finally, real-time experiments have been made on an autonomous car-like mobile robot called “Robucar”, developed to perform people transportation. Obtained results from experiments demonstrate the effectiveness of the proposed control strategy.
Model Reference Sliding Mode Control of Small Helicopter X.R.B based on Vision
Authors: Wang Wei , Nonami Kenzo , Ohira Yuta
Published: March 2012

This paper presents autonomous control for indoor small helicopter X.R.B. In case of natural disaster like earthquake, a MAV (Micro Air Vehicle) which can fly autonomously will be very effective for surveying the site and environment in dangerous area or narrow space, where human cannot access safely. In addition, it will be helpful to prevent secondary disaster. This paper describes vision based autonomous hovering control, guidance control for X.R.B by model reference sliding mode control.
Stability on Adaptive NN Formation Control with Variant Formation Patterns and Interaction Topologies
Authors: Chen Xin , Li Yangmin
Published: March 2012

The formation task achieved by multiple robots is a tough issue in practice, because of the limitations of the sensing abilities and communicating functions among them. This paper investigates the decentralized formation control in case of parameter uncertainties, bounded disturbances, and variant interactions among robots. To design decentralized controller, a formation description is firstly proposed, which consists of two aspects in terms of formation pattern and interaction topology. Then the formation control using adaptive neural network (ANN) is proposed based on the relative error derived from formation description. From the analysis on stability of the formation control under invariant/variant formation pattern and interaction topology, it is concluded that if formation pattern is of class Ck, k ≥1, and interaction graph is connected and changed with finite times, the convergence of the formation control is guaranteed, so that robots must form the formation described by the formation pattern.
Cooperation of Humanoid Robots Using Teleoperation for Transferring an Object
Authors: Keerio Muhammad Usman , Zhang Weimin , Jafri Ali Raza
Published: March 2012

In this paper, a method is proposed for humanoid robots performing object transfering task in a teleoperated cooperative paradigm. The cooperative task is accomplished using simple communication among two humanoid robots and then switch between modes according to the situation. In case of object passing with two humanoid robots, mutual position shifts may occur while they are moving. Therefore, it is necessary to correct the position in a real-time manner. To control the arm and hand of the robot remotely we use master arm and hand while it carries and passes the object, the dynamic stability during the execution of walking is ensured by incorporating the ZMP criterion and the desired spacing between the robots is controlled by Leader follower type control. Object passing cooperation for two humanoid robots is based on computer control, wireless LAN, vision, cooperative handling control and text commands. The method is applied as key software of the system. The effectiveness of the proposed methodology for performing cooperatively real time tasks is discussed.
Mechanical Design and Dynamcis of an Autonomous Climbing Robot for Elliptic Half-shell Cleaning
Authors: Zhang Houxiang , Zhang Jianwei , Liu Rong , Zong Guanghua
Published: March 2012

This paper presents an auto-climbing robot for cleaning the elliptic half-shell of National Grand Theatre in China. The robot consists of a climbing mechanism, a moving mechanism, two cleaning brushes and supporting mechanisms. The mechanism and unique aspects are presented in detail. A distributed control system based on CAN bus is designed to meet the requirements of controlling the robot. After that the emphasis for discussion is on the motion realization which includes climbing and cleaning movements. The robot independently climbs and descends in the vertical direction and cleans in the horizontal direction. It takes the circling tracks as supports for climbing up and down between strips and moving horizontally along one strip around the ellipsoid. For system design and control purposes, the dynamic models of the climbing and cleaning processes are given applying of the Lagrange equation. Furthermore the force distribution of the front and rear supporting mechanisms is computed in a way that ensures the safety of the climbing process. In the end, the successful on-site tests confirm the principles described above and the robot's ability.
A Component-Oriented Programming for Embedded Mobile Robot Software
Authors: Jawawi Dayang N. A. , Mamat Rosbi , Deris Safaai
Published: March 2012

Applying software reuse to many Embedded Real-Time (ERT) systems poses significant challenges to industrial software processes due to the resource-constrained and real-time requirements of the systems. Autonomous Mobile Robot (AMR) system is a class of ERT systems, hence, inherits the challenge of applying software reuse in general ERT systems. Furthermore, software reuse in AMR systems is challenged by the diversities in terms of robot physical size and shape, environmental interaction and implementation platform. Thus, it is envisioned that component-based software engineering will be the suitable way to promote software reuse in AMR systems with consideration to general requirements to be self-contained, platform-independent and real-time predictable. A framework for component-oriented programming for AMR software development using PECOS component model is proposed in this paper. The main features of this framework are: (1) use graphical representation for components definition and composition; (2) target C language for optimal code generation with resource-constrained micro-controller; and (3) minimal requirement for run-time support. Real-time implementation indicates that, the PECOS component model together with the proposed framework is suitable for resource constrained embedded AMR systems software development.
Real Time Mapping and Dynamic Navigation for Mobile Robots
Authors: Habib Maki K.
Published: March 2012

This paper discusses the importance, the complexity and the challenges of mapping mobile robot's unknown and dynamic environment, besides the role of sensors and the problems inherited in map building. These issues remain largely an open research problems in developing dynamic navigation systems for mobile robots. The paper presenst the state of the art in map building and localization for mobile robots navigating within unknown environment, and then introduces a solution for the complex problem of autonomous map building and maintenance method with focus on developing an incremental grid based mapping technique that is suitable for real-time obstacle detection and avoidance. In this case, the navigation of mobile robots can be treated as a problem of tracking geometric features that occur naturally in the environment of the robot. The robot maps its environment incrementally using the concept of occupancy grids and the fusion of multiple ultrasonic sensory information while wandering in it and stay away from all obstacles. To ensure real-time operation with limited resources, as well as to promote extensibility, the mapping and obstacle avoidance modules are deployed in parallel and distributed framework. Simulation based experiments has been conducted and illustrated to show the validity of the developed mapping and obstacle avoidance approach.
A Monocular Pointing Pose Estimator for Gestural Instruction of a Mobile Robot
Authors: Richarz Jan , Scheidig Andrea , Martin Christian , Müller Steffen , Gross Horst-Michael
Published: March 2012

We present an important aspect of our human-robot communication interface which is being developed in the context of our long-term research framework PERSES dealing with highly interactive mobile companion robots. Based on a multi-modal people detection and tracking system, we present a hierarchical neural architecture that estimates a target point at the floor indicated by a pointing pose, thus enabling a user to navigate a mobile robot to a specific target position in his local surroundings by means of pointing. In this context, we were especially interested in determining whether it is possible to accomplish such a target point estimator using only monocular images of low-cost cameras. The estimator has been implemented and experimentally investigated on our mobile robotic assistant HOROS. Although only monocular image data of relatively poor quality were utilized, the estimator accomplishes a good estimation performance, achieving an accuracy better than that of a human viewer on the same data. The achieved recognition results demonstrate that it is in fact possible to realize a user-independent pointing direction estimation using monocular images only, but further efforts are necessary to improve the robustness of this approach for everyday application.
Path Planning of Free-Floating Robot in Cartesian Space Using Direct Kinematics
Authors: Xu Wenfu , Liang Bin , Li Cheng , Xu Yangsheng , Qiang Wenyi
Published: March 2012

Dynamic singularities make it difficult to plan the Cartesian path of free-floating robot. In order to avoid its effect, the direct kinematic equations are used for path planning in the paper. Here, the joint position, rate and acceleration are bounded. Firstly, the joint trajectories are parameterized by polynomial or sinusoidal functions. And the two parametric functions are compared in details. It is the first contribution of the paper that polynomial functions can be used when the joint angles are limited(In the similar work of other researchers, only sinusoidla functions could be used). Secondly, the joint functions are normalized and the system of equations about the parameters is established by integrating the differential kinematics equations. Normalization is another contribution of the paper. After normalization, the boundary of the parameters is determined beforehand, and the general criterion to assign the initial guess of the unknown parameters is supplied. The criterion is independent on the planning conditions such as the total time tf. Finally, the parametes are solved by the iterative Newtonian method. Modification of tf may not result in the recalculation of the parameters. Simulation results verify the path planning method.
New Intelligent Transmission Concept for Hybrid Mobile Robot Speed Control
Authors: Mir-Nasiri Nazim , Hussaini Sulaiman
Published: March 2012

This paper presents a new concept of a mobile robot speed control by using two degree of freedom gear transmission. The developed intelligent speed controller utilizes a gear box which comprises of epicyclic gear train with two inputs, one coupled with the engine shaft and another with the shaft of a variable speed dc motor. The net output speed is a combination of the two input speeds and is governed by the transmission ratio of the planetary gear train. This new approach eliminates the use of a torque converter which is otherwise an indispensable part of all available automatic transmissions, thereby reducing the power loss that occurs in the box during the fluid coupling. By gradually varying the speed of the dc motor a stepless transmission has been achieved. The other advantages of the developed controller are pulling over and reversing the vehicle, implemented by intelligent mixing of the dc motor and engine speeds. This approach eliminates traditional braking system in entire vehicle design. The use of two power sources, IC engine and battery driven DC motor, utilizes the modern idea of hybrid vehicles. The new mobile robot speed controller is capable of driving the vehicle even in extreme case of IC engine failure, for example, due to gas depletion.