Performance study of a fractal UWB MIMO antenna for on-body WBAN applications

In this paper, a fractal ultrawideband multiple-input–multiple-output antenna is proposed and its characteristics are studied in free space as well as in the proximity of on-body wireless body area network scenario. The performance of the wideband antennas are affected strongly in the proximity of the human body. Koch fractal geometry is used at the outer edges of basic octagonal geometry in the design, which helps to achieve desired miniaturization, wideband and stable radiation pattern. The presented antenna has a compact size of 25 mm × 40 mm. In addition, the effect of body tissues on antenna characteristics is analyzed by a four layered (skin, fat, muscle and bone) human tissue model. The comparative analysis of S₂₁ is performed at a various body parts position such as abdomen, near forehead and chest with different antenna orientations.     

Influence of slab reheating practice on the microstructural evolution and toughness behavior of quenched and tempered plates of medium carbon microalloyed steel

In the current study, granular bainite was found to be the major component in the microstructure of air cooled 80 mm thick plates of medium carbon microalloyed steel. The second constituent in this granular bainite was identified as cementite. It was further observed that (1) ferrite lath size and (2) amount of cementite in granular bainite varied with slab reheating time before plate rolling. Smaller ferrite laths and a lesser amount of cementite were found in the plate processed with the longer slab reheating time of 26 h. Contrary to this, very large sized ferrite laths and a larger population of cementite were formed in the plate processed with the shorter slab reheating time of 4 h. Subsequent quenching and tempering of these plates favored the formation of lower bainite and tempered martensite in the plate with 26 h slab reheating time. On the other hand, upper bainite and coarser cementite were formed after the quenching and tempering of the plate with 4 h of slab reheating time. The influence of different microstructures, formed due to varied slab reheating time, on the toughness property of tempered plates was evaluated under different test conditions. In tensile test and fracture toughness testing of thinner specimens, a ductile mode of fracture was observed, irrespective of varied microstructures in the tempered plates. However, in the three-point bend test of full thickness specimens, the mode of fracture was ductile in the tempered plate with 26 h slab reheating time, while the tempered plate from the slab with 4 h reheating time gave rise to a predominantly brittle mode of fracture. These observations showed that the toughness property of these tempered plates was sensitive to the microstructure only under the specific condition, which prevailed during the three-point bend test of full thickness specimens. Under this condition, coarse cementite and upper bainite became prone to cracking resulting in a lower toughness of the tempered plate associated with lower slab reheating time.     

Degradation mechanism of galvanized steel in wet-dry cyclic environment containing chloride ions

The wet-dry cyclic test of a galvanized steel (GI) and pure zinc (ZN), which simulates marine atmospheric environment, has been conducted to clarify the degradation mechanism of galvanized steel. The samples were exposed to alternate conditions of 1 h-immersion in a 0.05 M NaCl solution and 7 h-drying at 25 °C and 60%RH, and the corrosion was monitored for 10 days (30 cycles) using a two-electrode type probe. Simultaneously, the corrosion potential was measured every three cycles only during the immersed conditions. The reciprocal of polarization resistance R_p⁻¹ was taken as an index of the corrosion rate. Several sample plates of GI and ZN were exposed, together with the monitoring probes. They were removed from the test chamber at the end of 1st, 3rd, 9th, 18th, and 30th cycles of exposure and were analyzed for the corrosion products with XRD and laser Raman spectroscopy. Further, their cross sections were analyzed with FESEM-EDS. The FESEM photographs and elemental analysis of cross sections confirmed that the R_p⁻¹ value commences to decrease when the corrosion front reaches Zn-Fe alloy layers (boundary layers of zinc coating and steel substrate) due to localized nature of attack. A schematic model of degradation mechanism and the role of galvanic protection have been discussed.     

Continuous case-based reasoning

Case-based reasoning systems have traditionally been used to perform high-level reasoning in problem domains that can be adequately described using discrete, symbolic representations. However, many real-world problem domains, such as autonomous robotic navigation, are better characterized using continuous representations. Such problem domains also require continuous performance, such as on-line sensorimotor interaction with the environment, and continuous adaptation and learning during the performance task. This article introduces a new method for continuous case-based reasoning, and discusses its application to the dynamic selection, modification, and acquisition of robot behaviors in an autonomous navigation system, SINS (self-improving navigation system). The computer program and the underlying method are systematically evaluated through statistical analysis of results from several empirical studies. The article concludes with a general discussion of case-based reasoning issues addressed by this research.     

A New and Faster Gaussian Elimination Based Fault Tolerant Systolic Linear System Solver

This paper presents a new systolic algorithm for thecompletesolution of a system ofNlinear equations in (N²/2 +O(N)) time steps using 2Nprocessing elements (PEs). It is based on a variant of the Gaussian elimination (GE) algorithm called the successive GE and is faster than any existing GE based algorithm usingO(N) PEs. We also suggest two fault tolerant schemes that tolerate up toNPE failures. The first scheme is a time redundancy based approach with no hardware overhead and 100% time overhead. This scheme can tolerate up toNPE failures. The second scheme is based on algorithm based fault tolerance (ABFT) and usesNextra PEs to tolerate up toN− 1 PE failures with very little time overhead. The number of errors that can be detected/corrected in both schemes is more than that in any existing fault tolerant systolic array.     

QoE Aware IoT Application Placement in Fog Computing Using Modified-TOPSIS

Mobile Networks and Applications - Over the years, fog computing has emerged as a paradigm to complement the cloud computing in handling the delay sensitive IoT applications in a better manner....     

Load balancing in a heterogeneous world: CPU-Xeon Phi co-execution of data-parallel kernels

Heterogeneous systems composed by a CPU and a set of different hardware accelerators are very compelling thanks to their excellent performance and energy consumption features. One of the most important problems of those systems is the workload distribution among their devices. This paper describes an extension of the Maat library to allow the co-execution of a data-parallel OpenCL kernel on a heterogeneous system composed by a CPU and an Intel Xeon Phi. Maat provides an abstract view of the heterogeneous system as well as set of load balancing algorithms to squeeze the performance out of the node. It automatically performs the data partition and distribution among the devices, generates the kernels and efficiently merges the partial outputs together. Experimental results show that this approach always outperforms the baseline with only a Xeon Phi, giving excellent performance and energy efficiency. Furthermore, it is essential to select the right load balancing algorithm because it has a huge impact in the system performance and energy consumption.

     

An SMVQ-based reversible data hiding technique exploiting side match distortion

Secure online communication is a necessity in today’s digital world. This paper proposes a novel reversible data hiding technique based on side match vector quantization (SMVQ). The proposed scheme classifies SMVQ indices as Case 1 or 2 based on the value of the first state codeword’s side match distortion (SMD) and a predefined threshold t. The proposed scheme uses this classification to switch between compression codes designed for Cases 1 and 2 SMVQ indices. The length of these compression codes is controlled by the parameter ?. Thus, with the selection of appropriate ? and t values, the proposed scheme achieves good compression, creating spaces to embed secret information. The embedding algorithm can embed n secret bits into each SMVQ index, where n = 1, 2, 3, or 4. The experimental results show that the proposed scheme obtains the embedding rates of 1, 2, 3, or 4 bit per index (bpi) at the average bit rates of 0.340, 0.403, 0.465, or 0.528 bit per pixel (bpp) for the codebook size 256. This improves the performance of recent VQ and SMVQ-based data hiding schemes.