Mirror effects on dynamic response of surface-emitting lasers

The effects of longitudinal wave distribution and mirror structures on the small-signal response of surface-emitting lasers are analyzed for the first time. The analysis is based on an improved dynamic model implemented in the transfer-matrix representation. It is shown that for two structures with the same threshold gain and the same internal structure, high contrast mirrors give rise to a higher relaxation oscillation and modulation bandwidth for the same injection level     

Microscale elastic strain evolution following damage in Ti-SiC composites

Fiber fractures are crucial in initiating damage zones that ultimately determine the strength and lifetime of fiber-reinforced metal matrix composites. The evolution of damage in a metal matrix composite (MMC) comprised of a row of unidirectional SiC fibers (32 vol pct) surrounded by a Ti matrix was examined, for the first time, using X-ray microdiffraction. Multiple strain maps including both phases were collected in situ under applied tensile stress. The elastic axial strains were then compared to predictions from a modified shear-lag model, which, unlike other shear-lag models, considers the elastic response of both constituents. The strains showed good correlation with the model. The results confirmed, for the first time, both the need and validity of this new model specifically developed for large scale multifracture simulations of MMCs. The results also provided unprecedented insight for the model, revealing the necessity of incorporating such factors as plasticity of the matrix, residual stress in the composite, and selection of the load sharing parameter.     

Bidirectional coroutines

The bidirectional coroutine is introduced as a mechanism for overcoming a shortcoming in the method of specification of the transfer of control between coroutines. An analogy is drawn between subroutines and coroutines by observing that coroutines, like subroutines, should not have to know with whom they are interacting. At present, most coroutine implementations require specific mention of the coroutine being resumed, or use a suspend mechanism in which case one coroutine acts as a slave (the suspending one) and the other as a master. In the second case, the slave need not know the identity of its master while the master must know the identity of its slave. For bidirectional coroutines, a coroutine need not know the identity of its master nor its slave. This is achieved by replacing the suspend primitive with two new primitives — resume master and resume slave.     

Shape approximation using quadtrees

The quadtree representation encodes a 2″ by 2″ binary image as a set of maximal blocks of 1's or 0's whose sizes and positions are powers of 2. With the aid of the quadtree, a hierarchy of approximations to the image can be defined. Several ways of doing this are described. The accuracy of these approximations is empirically evaluated by studying how fast estimates of the first few moments of the image, computed from the approximations, converge to the true values, using a database of 112 airplane silhouettes. Approaches to the problem of fast shape matching using these approximations are also discussed.     

Automatic Eyewitness Identification During Disasters by Forming a Feature-Word Dictionary

Social media provide digitally interactional technologies to facilitate information sharing and exchanging individuals. Precisely, in case of disasters, a massive corpus is placed on platforms such as Twitter. Eyewitness accounts can benefit humanitarian organizations and agencies, but identifying the eyewitness Tweets related to the disaster from millions of Tweets is difficult. Different approaches have been developed to address this kind of problem. The recent state-of-the-art system was based on a manually created dictionary and this approach was further refined by introducing linguistic rules. However, these approaches suffer from limitations as they are dataset-dependent and not scalable. In this paper, we proposed a method to identify eyewitnesses from Twitter. To experiment, we utilized 13 features discovered by the pioneer of this domain and can classify the tweets to determine the eyewitness. Considering each feature, a dictionary of words was created with the Word Dictionary Maker algorithm, which is the crucial contribution of this research. This algorithm inputs some terms relevant to a specific feature for its initialization and then creates the words dictionary. Further, keyword matching for each feature in tweets is performed. If a feature exists in a tweet, it is termed as 1; otherwise, 0. Similarly, for 13 features, we created a file that reflects features in each tweet. To classify the tweets based on features, Naïve Bayes, Random Forest, and Neural Network were utilized. The approach was implemented on different disasters like earthquakes, floods, hurricanes, and Forest fires. The results were compared with the state-of-the-art linguistic rule-based system with 0.81 F-measure values. At the same time, the proposed approach gained a 0.88 value of F-measure. The results were comparable as the proposed approach is not dataset-dependent. Therefore, it can be used for the identification of eyewitness accounts.     

Novel type-2 fuzzy logic technique for handover problems in a heterogeneous network

Small cells are deployed in the long-term evolution—advanced (LTE-A) data standard to satisfy rapidly increasing data rates at hotspots and enhance coverage in buildings. Small cells are low-cost, low-power nodes with limited coverage. With small cells, the more sophisticated network architecture increases the difficulty of dealing with mobility management. The conflict between traffic demands and network resources is also very important, and the signalling overhead (ping-pong) in the handover procedure should be considered in mobility management. With the aim of solving these issues, efficient handover algorithms are being used to enhance mobility management in small-cell networks. This article presents a new handover optimization algorithm for LTE-A networks based on fuzzy logic. It consists of selecting the optimum handover margins for both macro and small cells which are required for the handover process to optimize the performance metrics. The proposed handover optimization technique is evaluated and compared with two well-known handover algorithms. The results show that it achieves a minimum call drop rate and has a minimum number of handovers.     

Preparation and characterization of novel bio-composites based on functionalized zeolite and nano-hydroxyapatite for a potential application in bone treatment

Journal of Porous Materials - This work was aiming to design novel bio-composite (BC) materials based on microwave-prepared AuNPs-loaded Zeolite-A (ZA-Au) and nano-hydroxyapatite (HA)....     

Multi-facial patches aggregation network for facial expression recognition and facial regions contributions to emotion display

Multimedia Tools and Applications - In this paper, an approach for Facial Expressions Recognition (FER) based on a multi-facial patches (MFP) aggregation network is proposed. Deep features are...     

K-nearest neighbor finding using MaxNearestDist

Similarity searching often reduces to finding the k nearest neighbors to a query object. Finding the k nearest neighbors is achieved by applying either a depth- first or a best-first algorithm to the search hierarchy containing the data. These algorithms are generally applicable to any index based on hierarchical clustering. The idea is that the data is partitioned into clusters which are aggregated to form other clusters, with the total aggregation being represented as a tree. These algorithms have traditionally used a lower bound corresponding to the minimum distance at which a nearest neighbor can be found (termed MinDist) to prune the search process by avoiding the processing of some of the clusters as well as individual objects when they can be shown to be farther from the query object q than all of the current k nearest neighbors of q. An alternative pruning technique that uses an upper bound corresponding to the maximum possible distance at which a nearest neighbor is guaranteed to be found (termed MaxNearestDist) is described. The MaxNearestDist upper bound is adapted to enable its use for finding the k nearest neighbors instead of just the nearest neighbor (i.e., k=1) as in its previous uses. Both the depth-first and best-first k-nearest neighbor algorithms are modified to use MaxNearestDist, which is shown to enhance both algorithms by overcoming their shortcomings. In particular, for the depth-first algorithm, the number of clusters in the search hierarchy that must be examined is not increased thereby potentially lowering its execution time, while for the best-first algorithm, the number of clusters in the search hierarchy that must be retained in the priority queue used to control the ordering of processing of the clusters is also not increased, thereby potentially lowering its storage requirements.     

Weighted link quality and forward progress coupled with modified RTS/CTS for beaconless packet forwarding protocol (B-PFP) in VANETs

Telecommunication Systems - The Internet Engineering Task Force recommends the use of a group of well-defined protocols to support Internet of ThingsLow-Power Low-Rate Networks (LLNs). These...