Recursive Update Algorithm for Least Squares Support Vector Machines

In this Letter an efficient recursive update algorithm for least squares support vector machines (LSSVMs) is developed. Using the previous solution and some matrix equations, the algorithm completely avoids training the LSSVM all over again whenever new training sample is available. The gain in speed using the recursive update algorithm is illustrated on four data sets from UCI repository: the Statlog Australian credit, the Pima Indians diabetes, the Wisconsin breast cancer, and the adult income data sets.     

The modification of the characteristics of ZnO nanofibers by TCNQ doping content

In this study, the electrical properties of an Al/p-Si metal/semiconductor photodiodes with Tetracyanoquinodimethane–Polyvinyl chloride (TCNQ–PVC) and PVC–TCNQ:ZnO interfacial layers were investigated. Growing of the interfacial layers on p-Si were fulfilled using electrospinning method as a fiber form. Al metallic and ohmic contacts were deposited via physical vapor deposition method. Scanning electron microscopy (SEM) pictures of the devices were captured to examine the morphology of the structure. Within the scope of electrical characterization, I–V measurements of the Al/PVC–TCNQ/p-Si and Al/PVC–TCNQ:ZnO/p-Si devices were accomplished both in the dark and under illumination conditions. Various device parameters, such as ideality factor and barrier height values were determined from I–V characteristics. Although the ideality factor values were obtained as 8.47 and 6.85 for undoped and ZnO-doped Al/PVC–TCNQ/p-Si diodes, the barrier height values were calculated as 0.84 for both devices. When a comparison was made between ZnO doped and undoped Al/PVC–TCNQ/p-Si diodes, it was evaluated that the rectification and photoresponse properties of the heterojunction diode was improved with ZnO dopant.

     

Use of consistency index, expert prioritization and direct numerical inputs for generic fuzzy-AHP modeling: A process model for shipping asset management

The aim of this paper is to develop a generic version of the conventional fuzzy-analytic hierarchy process (FAHP) method and investigate the shipping asset management (SAM) problem in the dry bulk shipping market. The recent literature has various applications of the FAHP, but these studies lack consistency control, use identical decision support rather than weighted expert choices, and lack measurable criteria. The proposed model, generic fuzzy-AHP (here after GF-AHP), provides a standard control of consistency on the decision matrix for the expert group. GF-AHP also improves the capabilities of the FAHP by executing direct numerical inputs without expert consultation. In practical business, some of the criteria can be easily calculated and expert consultation is a redundant process. Therefore, GF-AHP presents how to transform such numerical inputs to a priority scale. Finally, expertise differences on the decision group are reflected in the GF-AHP process by an expert weighting algorithm.     

Bond strength of repaired composite resins: surface treatments,adhesive systems,and composite type

The aim of the present study was to investigate the effects of three different surface treatments and two different adhesives on the microtensile bond strength (μTBS) of repaired composites using the same or different type of resin. Twenty-four nano-hybrid (Ceram X mono-C) and 24 nanofilled (Filtek Ultimate-F) composite discs were prepared. The specimens were aged with 5000 thermocycles and randomly divided into groups according to the surface treatment methods: (a) phosphoric acid (b) Er:YAG laser and (c) aluminum trioxide particle (air abrasion). Fresh composite resins (C and F) were added to the treated surfaces with two different adhesives (two-step and one-step self-etch adhesives). Then, the specimens were aged again. The stick-shaped specimens were prepared from the discs (n = 25) and the sticks were subjected to the μTBS test. Results indicated that significant differences were found in μTBS values among the surface treatment methods. In the C groups, the highest μTBS value (41.3 ± 8.3 MPa) was recorded in the air abrasion and one-step self-etch adhesive group, which were repaired with the same kind of composite. In the F groups, the highest μTBS value was observed in the air abrasion and one-step self-etch adhesive (37.6 ± 12.3 MPa) group. The treatment with air abrasion is more effective than the others, and it may be suggested for composite repair.     

Roll forming of branched profiles

Due to the new mass forming process “linear flow splitting” forming of branched profiles in integral style out of sheet metal without joining, lamination of material or heating of the semi-finished part becomes feasible. Since the resulting flanges provide extra stiffness without increasing the weight of the semi-finished product, split profiles are suitable especially for lightweight applications. The combination of the linear flow splitting process with a following roll-forming process enables the continuous production of one- or multi-chambered profiles with free flanges. In this paper phenomena occurring during roll forming of branched profiles are described and discussed.     

Multiuser Detection Techniques for Hierarchical Cell Structures in CDMA Cellular Systems

CDMA-only microcell/macrocell cellular systems have traditionally suffered from the near-far problem in the microcells located near the macrocell boundary. Strong macrocell interference in these microcells disables conventional single-user detectors. The solutions currently adopted in the literature include bandwidth-consuming frequency separation between macrocell and microcell tiers and complex hybrid architectures. In this work we present the techniques for multiuser receiver design that address this problem. The preprocessing stage, called the projection stage, which projects the received signal onto the space orthogonal to the subspace spanned by macrocell users' signature sequences, is introduced. It is followed by the stage employing conventional multiuser detection (MUD) techniques. This class of detectors, called multiuser projection detectors (MPD), provides efficient protection against macrocell interference in all microcells, regardless of their location within the macrocell. The protection is optimal if the amplitudes of macrocell interferers are not known by the microcell BS. We analyze four MPDs using different MUD techniques in the detection stage, and perform performance comparison.     

Diagnostic value of electrical stimulation of lumbosacral roots in radiculopathies

Needle electrical stimulation of the lumbosacral roots at the laminar level of the Th12-L1 or L1-2 intervertebral spaces were performed in 24 normal subjects and 58 patients with various kinds of lumbar radiculopathy (unilateral L4, L5 and S1 herniated nucleus pulposus and lumber stenosis). The root stimulation method was compared with conventional needle EMG. Lumber electrical stimulation showed root abnormalities objectively in 80% of patients while the diagnostic value of needle EMG was 65%. Therefore, electrical root stimulation is superior to routine EMG for localizing lumbar root involvement. However, the only needle EMG demonstrated the root pathology in 7 cases (12%) and single electrophysiological abnormality was found by the root stimulation in 16 cases (27%). Thus, both electrophysiological methods should be complementary to each other in evaluation of the lumbar radioculopathy.     

A Photoluminescent Polymeric 2D Silver(I) Complex Exhibits a Fishbone-like 1D Silver Cluster and New Coordination Mode of the Pyridine-2,3-Dicarboxylate

In this study, a novel organic–inorganic hybrid compound with AgNO₃ and 2,3-pyridinedicarboxylic acid (H₂pydc), [Ag₂(μ₆-pydc)]_n (1) has been synthesized. The molecular structure of complex has been determined by the single crystal X-ray diffraction. The complex has been observed to crystallize in the monoclinic space group P2₁/c. The asymmetric unit of compound consists of two crystallographically different Ag(I) centers and one pydc ligand. The Ag1 and Ag2 adopt tetrahedral and T-shaped geometries, respectively. At the same time, the silver(I) compound consists of a fish bone similar to the 1D silver cluster. Furthermore, novel coordination mode shown by H₂pydc indicates that the crystal exhibits photoluminescence in the solid state at room temperature.     

Selective thermal recycling for graphene growth on natural substrates: A comparative study on life cycle assessment,energy consumption,and mechanical performance in recompounding

Manufacturing of carbon-based materials from waste thermoplastics is a keystone to reduce adverse environmental impacts. There are numerous attempts for sustainable graphene manufacturing from various waste sources by thermal treatment but there is no clear distinction on the effective conversion process by addressing reliable CO₂ footprints. This study provides a comprehensive benchmarking study on the conversion of waste polypropylene plastics coming from yogurt containers into graphene on the substrate of talc by applying two upcycling techniques of catalytic carbonization (CC) and flash pyrolysis (FP) by comparing energy and speed of the processes and a dimensional stability and physical characteristics of the produced graphene substances by adopting a comparative life cycle assessment. FP led to the sphericalization of graphenes due to fast dehydration, cross-linking, and carbonization of aromatic structures. On the other hand, gradual heating in CC caused the formation of tubular-like graphene structures. In addition, FP became advantageous by resulting in 52% of CO₂ emission compared with CC process. On the other hand, graphenes separated from talcs exhibited a remarkable 70% reduction in global warming potential compared with conventional graphene production from graphite. In order to complete the value chain and circularity, the mechanical performance of two different hybrid additives produced by selective thermal recycling in recompounding with copolymer polypropylene was examined, and additives from CC enhanced the flexural and tensile properties two times better than the one from FP. With this study, it becomes possible to compare analysis of graphene growth on natural substrates by exploring life cycle assessment, energy consumption, and mechanical performance with selective thermal recycling and recompounding.