Gray-Level Reduction Using Local Spatial Features

This paper proposes a new method for reduction of the number of gray-levels in an image. The proposed approach achieves gray-level reduction using both the image gray-levels and additional local spatial features. Both gray-level and local feature values feed a self-organized neural network classifier. After training, the neurons of the output competition layer of the SOFM define the gray-level classes. The final image has not only the dominant image gray-levels, but also has a texture approaching the image local characteristics used. To split the initial classes further, the proposed technique can be used in an adaptive mode. To speed up the entire multithresholding algorithm and reduce memory requirements, a fractal scanning subsampling technique is adopted. The method is applicable to any type of gray-level image and can be easily modified to accommodate any type of spatial characteristic. Several experimental and comparative results, exhibiting the performance of the proposed technique, are presented.     

Atlas: Storing, updating and querying RDF(S) data on top of DHTs

The RDF(S) data model has been proposed for encoding metadata about Web resources. As more and more Web resources are annotated using RDF(S), there is an urgent need for efficiently dealing with this large volume of data. In this paper, we present Atlas, a peer-to-peer system for storing, updating and querying RDF(S) data. The Atlas system has been built using the distributed hash table Bamboo. Atlas was developed in the context of project OntoGrid, where it was used as a distributed repository for RDF(S) metadata describing Grid services and resources. The development of Atlas continues in other projects that our group participates currently. This paper gives an overview of the most recent version of Atlas and discusses a representative application.     

Adaptive and reliable video transmission over UMTS for enhanced performance

This paper proposes a mechanism for the congestion control for video transmission over universal mobile telecommunications system (UMTS). Our scheme is applied when the mobile user experiences real‐time multimedia content and adopts the theory of a widely accepted rate control method in wired networks, namely equation‐based rate control. In this approach, the transmission rate of the multimedia data is determined as a function of the packet loss rate, the round trip time and the packet size and the server explicitly adjusts its sending rate as a function of these parameters. Furthermore, we examine the performance of the UMTS for real‐time video transmission using real‐time protocols. Through a number of experiments, we measure performance parameters such as end‐to‐end delay, delay in radio access network, delay jitter and throughput in the wireless link. Copyright © 2006 John Wiley & Sons, Ltd.     

Augmentative Pharmacological Strategies in Treatment-Resistant Major Depression: A Comprehensive Review

Treatment resistant depression (TRD) is associated with poor outcomes, but a consensus is lacking in the literature regarding which compound represents the best pharmacological augmentation strategy to antidepressants (AD). In the present review, we identify the available literature regarding the pharmacological augmentation to AD in TRD. Research in the main psychiatric databases was performed (PubMed, ISI Web of Knowledge, PsychInfo). Only original articles in English with the main topic being pharmacological augmentation in TRD and presenting a precise definition of TRD were included. Aripiprazole and lithium were the most investigated molecules, and aripiprazole presented the strongest evidence of efficacy. Moreover, olanzapine, quetiapine, cariprazine, risperidone, and ziprasidone showed positive results but to a lesser extent. Brexpiprazole and intranasal esketamine need further study in real-world practice. Intravenous ketamine presented an evincible AD effect in the short-term. The efficacy of adjunctive ADs, antiepileptic drugs, psychostimulants, pramipexole, ropinirole, acetyl-salicylic acid, metyrapone, reserpine, testosterone, T3/T4, naltrexone, SAMe, and zinc cannot be precisely estimated in light of the limited available data. Studies on lamotrigine and pindolol reported negative results. According to our results, aripiprazole and lithium may be considered by clinicians as potential effective augmentative strategies in TRD, although the data regarding lithium are somewhat controversial. Reliable conclusions about the other molecules cannot be drawn. Further controlled comparative studies, standardized in terms of design, doses, and duration of the augmentative treatments, are needed to formulate definitive conclusions.     

Forming of Ceramics during Firing without the Application of External Pressure

A method to form thin ceramic bodies is described in which curvature in the component is introduced at high temperature without the application of an external stress. The internal stress that drives the deformation results as a consequence of cation penetration from a coating into a substrate material. This technique has been developed for alumina substrates that are coated with layers of chromia, magnesia, titania, calcia, silica, and iron oxide. Normalized deflections of segment height to sample thickness ( A/t ) of up to 10 were observed for samples with beam geometry and A/t values of 4 were obtained for disks. The magnitude of the deflection is dependent on the amount of dopant that is applied, as well as the soak temperature and time. An analytical model has been developed to describe the magnitude of the deflections. The best agreement with the experimental data is obtained when the deflections are treated as occurring at high temperature, where the resistance to bending from stiffness effects is reduced. This forming method is shown to be suitable to produce shapes of moderate complexity, such as ceramic wave springs.     

Modified cassava starch/poly(vinyl alcohol) blend films plasticized by glycerol: Structure and properties

We report a systematic investigation on the structure–property relationships in glycerol-plasticized poly(vinyl alcohol) (PVA)/cassava starch blends prepared via solution casting. In particular, PVA mixed with native, low-oxidized, high-oxidized, and pregelatinized cassava starches were characterized by means of SEM, XRD, FTIR, thermal analysis and mechanical testing and the immiscible systems were received. Burial tests over a period of several days suggested the preferential degradation of the starch and glycerol component (as indicated by the absence of FTIR signatures of those components) and the amorphous phase of PVA (as indicated by the enhanced crystallinity index of the degraded samples). The rheological properties of the blends seem to dictate their morphological characteristics that, in turn, have a profound impact on their mechanical properties. In that sense, the study highlights promising strategies for the development of a new family of polymeric materials that combine their biodegradable nature within superior mechanical properties. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48848.     

Processing and Mechanical Properties of Ti3SiC2: II, Effect of Grain Size and Deformation Temperature

In this article, the second part of a two-part study, we report on the mechanical behavior of Ti₃SiC₂. In particular, we have evaluated the mechanical response of fine-grained (3–5 μm) Ti₃SiC₂ in simple compression and flexure tests, and we have compared the results with those of coarse-grained (100–200 μm) Ti₃SiC₂. These tests have been conducted in the 25°–1300°C temperature range. At ambient temperature, the fine- and coarse-grained microstructures exhibit excellent damage-tolerant properties. In both cases, failure is brittle up to ∼1200°C. At 1300°C, both microstructures exhibit plastic deformation (>20%) in flexure and compression. The fine-grained material exhibits higher strength compared with the coarse-grained material at all temperatures. Although the coarse-grained material is not susceptible to thermal shock (up to 1400°C), the fine-grained material thermally shocks gradually between 750° and 1000°C. The results presented herein provide evidence for two important aspects of the mechanical behavior of Ti₃SiC₂: (i) inelastic deformation entails basal slip and damage formation in the form of voids, grain-boundary cracks, kinking, and delamination of individual grains, and (ii) the initiation of damage does not result in catastrophic failure, because Ti₃SiC₂ can confine the spatial extent of the damage.     

Residual Stress Fields at the Surface of Sharp Pyramid Indentations

This paper describes an experimental measurement of the residual stress field around Berkovich and Knoop indentations on the surface of soda-lime glass. The isostress contours of both the residual tensile and compressive stress are presented. The results are compared with similar measurements around Vickers indentations on the same glass. The residual stress field around all three different shapes of indentations is clearly nonequal biaxial, with characteristic differences in the form of the stress contours that relate to each specific shape. The results for Berkovich indentation are compared with finite element (FEM) numerical calculations. Some general conclusions related to the sharp indentations are deduced from this study.     

An Algorithm for Adaptive Mean Filtering and Its Hardware Implementation

Noise due to the sensor and the electronics of a camera is an undesirable issue in any machine vision application. Such noise tends to corrupt images and to obstruct any further analysis. An algorithm to detect and cancel such noise, using statistical methods, is presented in this paper. The proposed algorithm is an adaptive mean filter, which filters out image regions that are found to be noise corrupted. The efficiency of the proposed filter was examined both qualitatively and quantitatively, by software simulation in several noisy conditions. The main advantage of the filter in hand is that it is appropriate for hardware implementation and can be easily incorporated to smart cameras. The hardware implementation of the filter is also presented in this paper. This implementation aims at time critical applications such as machine vision, inspection and visual surveillance. Ioannis Gasteratos holds a Diploma in Electrical Engineering from the Department of Electrical and Computer Engineering, Democritus University of Thrace, Greece, 2004. His research interests include digital VLSI design, computer architectures and artificial intelligence. He is a member of the IEEE, and a member of the Technical Chamber of Greece (TEE). Antonios Gasteratos is a Lecturer of Robotics in the Department of Production and Management, Democritus University of Thrace, Greece. He holds a PhD from the Department of Electrical and Computer Engineering, Democritus University of Thrace, Greece, 1999. During 2001–2003 he was a visiting Assistant Professor in the Department of Electrical and Computer Engineering, Democritus Univesrsity of Thrace. He serves as a reviewer to numerous of Scientific Journals and International Conferences. His research interests are mainly in computer and robot vision and sensory data fusion. He is a member of the IEEE, the IAPR, the EURASIP, the Hellenic Society of Artificial Intelligence (SETN) and the Technical Chamber of Greece (TEE). Ioannis Andreadis received the Diploma Degree from the Department of Electrical & Computer Engineering, DUTH, Greece, in 1983 and the MSc and PhD Degrees from the University of Manchester Institute of Science & Technology, UK, in 1985 and 1989, respectively. His research interests are mainly in Intelligent Systems, Machine Vision and VLSI based computing architectures. He joined the Department of Electrical & Computer Engineering, DUTH in 1993. He is a member of the Editorial Board of the Pattern Recognition Journal, TEE and IEEE.     

Modeling the effect of chemotaxis on glioblastoma tumor progression

Tumor progression depends on the intricate interplay between biological processes that span the molecular and macroscopic scales. A mathematical agent‐based model is presented to describe the 3‐D (three‐dimensional) progression of a brain tumor type (i.e., glioblastoma multiforme) as the collective behavior of individual tumor cells whose fate is determined by intracellular signaling pathways (i.e., MAPK pathway) that are governed by the temporal‐spatial distribution of key biochemical cues (i.e., growth factors, nutrients). The model is used to investigate how tumor growth and invasiveness depend on the response of migrating tumor cells to chemoattractants. Simulation results suggest that individual cell sensitivity to chemical gradients is necessary to generate in silico tumors with the irregular shape and diffusive tumor‐stroma interface characteristic of glioblastomas. In addition, vascular network damage influences tumor growth and invasiveness. The results quantitatively recapitulate the central role that nutrient availability and signaling proteins have on tumor invasive properties. © 2010 American Institute of Chemical Engineers AIChE J, 2011