System load model for the OFDMA network

In this letter we introduce our system load model for the orthogonal frequency division multiple access (OFDMA) network. We formulate the requirements to the system load model and present its definition. The system load model comprises the uplink load, the downlink load, the sector load, and the network load. We describe our approach to combine the time-frequency and power shared system resources in the OFDMA network.     

Intelligent Selection of Instances for Prediction Functions in Lazy Learning Algorithms

Lazy learning methods for function prediction use different prediction functions. Given a set of stored instances, a similarity measure, and a novel instance, a prediction function determines the value of the novel instance. A prediction function consists of three components: a positive integer k specifying the number of instances to be selected, a method for selecting the k instances, and a method for calculating the value of the novel instance given the k selected instances. This paper introduces a novel method called k surrounding neighbor (k-SN) for intelligently selecting instances and describes a simple k-SN algorithm. Unlike k nearest neighbor (k-NN), k-SN selects k instances that surround the novel instance. We empirically compared k-SN with k-NN using the linearly weighted average and local weighted regression methods. The experimental results show that k-SN outperforms k-NN with linearly weighted average and performs slightly better than k-NN with local weighted regression for the selected datasets.     

Inverse cartesian trajectory control and stabilization of a three-axis flexible manipulator

This article treats the question of end point trajectory control of a flexible manipulator based on the nonlinear inversion technique. The manipulator has two rigid links and the third link is elastic. A parameterization of the Cartesian coordinates of a point close to the end effector position is suggested. Using these coordinates as output variables, an inverse feedback control law is derived for tracking reference Cartesian trajectories. The stability of the zero dynamics associated with the end point motion control is examined. It is shown that inverse control of the end point causes divergent oscillatory flexible modes. In addition, for regulating the end point to a fixed position, a linear stabilizer is designed to damp the elastic vibration. Simulation results are presented to show that in the closed-loop system, reference end point trajectories can be accurately followed in spite of the parameter uncertainty in the arm dynamic model. © 1994 John Wiley & Sons, Inc.     

First‐principles study in an inter‐granular glassy film model of silicon nitride

Based on a previously constructed intergranular glassy film (IGF) model for bulk silicon nitride, a large periodic model of 3864 atoms containing 2 grains of different orientations from the main bulk β‐Si₃N₄ and 2 IGFs was fully relaxed using the ab initio density‐functional theory package VASP. The relaxed structure was then used to calculate the electronic structure, density of states, interatomic bonding, partial charge distribution, and electron localization using the OLCAO method. Analysis of the data focuses on the interfacial regions between bulk β‐Si₃N₄ and the Si‐O‐N glass layer with different orientations. The total bond order density (TBOD) is evaluated in different interfacial and bulk regions. We show minor differences in the internal cohesion between crystalline grains of different facets. However, the overall charges in the bulk crystal grains and in the glassy regions are electropositive which are balanced by the negatively charged interfacial region between the two. The presence of a less rigid glassy layer is the reason for structural flexibility in ceramics without a huge penalty in the steric energy. The optimization of the interfacial structure and bonding via the creation of defective sites is the atomic origin for the existence of the IGF in silicon nitride. The insights obtained from this detailed quantum mechanical analysis of a realistic IGF model are discussed including implications on the strength, fracture toughness, and processing methods. We also discuss the potential applications of our method to other complex materials systems.     

Preparation of PEDOT-ordered mesoporous carbon hybrid material using vapor phase polymerization

A hybrid composite was prepared by the formation of poly (3,4-ethylenedioxythiophene) (PEDOT) layer on two types of ordered mesoporous carbon (OMC) by vapor phase polymerization. The morphology, chemical composition, pore structure, and electrical properties of the normal type ordered mesoporous carbon (NTOMC) and rod type ordered mesoporous carbon (RTOMC) composites were compared and analyzed. The surface morphology of the PEDOT-OMC composite did not change, due to the uniform coating of PEDOT layer on the OMC. The content of PEDOT in the composite and the thickness of the coating layer both increased with the amount of the oxidizing agent, Iron (III) p-toluenesulfonate (FTS) used in VPP. Pore size, porosity, and surface area of PEDOT-OMC composite decreased with coating of PEDOT layer on the outer surface of the OMC, and the mesopore inner wall. Electrical resistance decreased with an increase in the thickness of the PEDOT layer coated on the OMC. The PEDOT-RTOMC composite had lower electrical resistivity than the PEDOT-NTOMC composite, suggesting that rod-type morphology is advantageous for electron transport. The capacitance was also higher for the PEDOT-RTOMC than for the PEDOTNTOMC, which is thought to be proportional to the surface area of the composite determined by the external and internal structure of the material.     

An integrated CAE system for dynamic stress and fatigue life prediction of mechanical systems

This paper presents computer simulation methodology for dynamic stress time history computation to predict the fatigue life of machine components using flexible multi-body dynamics. A hybrid method which employes stress superposition as a function of constraint loads and component accelerations that are predicted by flexible body dynamic simulation is utilized and implemented using established codes. A system integration methodology for dynamic stress computation of mechanical system components is described to provide a usable environment for an engineer. It uses a database management system such as the IAC and the established dynamics and finite element analysis codes.     

Analysis of restriction fragment length polymorphism in the bovine growth hormone gene related to growth performance and carcass quality of Korean Native Cattle

This research was conducted to find restriction fragment length polymorphism (RFLP) markers related to growth performance and meat quality of Korean Native Cattle. DNA was extracted from the blood of Korean Native Cattle steers and Southern blot analysis of genomic DNA digested with restriction enzymes was performed using a bovine growth hormone (GH) cDNA probe. The restriction enzyme that detected RFLPs most frequently was TaqI. Digested fragments with TaqI revealed 6.15, 5.2, 4.5, 4.3, 2.6, 2.4, 1.6, 0.5, 0.3 and 0.2 kb bands. The most frequent band was 1.6 kb, which was exhibited in 11 out of 15 animals. In GH-TaqI RFLP, the 4.3 kb band was correlated with average daily gain (p = 0.021) and carcass weight (p = 0.035). No markers related to meat quality were found.     

Study on the transaction linkage technique combined with the designated terminal for 5G-enabled IoT

With the growth of the scale of the market for Internet banking and e-commerce, the number of Internet-based financial markets has been increasing. Meanwhile, hacking incidents continuously affect Internet-banking services. For this reason, a countermeasure is required to improve the security of the online identification process. The current security and authentication mechanisms applied to financial services, such as Internet banking services for 5G-enabled IoT, do not ensure security. In this paper, a transaction-linkage technique with which the designated terminal is combined is proposed to solve this fundamental problem. The technique improves the security of online identification mechanisms because it is possible to counteract all of the existing security threats. The proposed technique supports mutual authentication and is safe from eavesdropping attacks, replay attacks, spoofing attacks, and service-denial attacks. Moreover, the technique supports non-repudiation by storing the transaction history in a transaction-linkage device. We believe that the security of Internet-banking services for 5G-enabled IoT will be increased through the utilization of the proposed technique.     

Role of coagulation in membrane filtration of wastewater for reuse

This study explains the role of coagulation in membrane filtration of wastewater for reuse. For this purpose, a coagulation-ultrafiltration (UF) membrane system was used to treat secondary effluent from a nearby wastewater treatment plant using a rotating biological contactor. The study proceeded with the hypothesis that coagulation could affect membrane filtration through two phenomena: change in particle characteristics and contaminant loading reduction. If fouling reduction were observed at a low alum dosage, coagulation would affect membrane performance by changing particle characteristics because contaminant reduction could not be possible at low dosage. If fouling reduction were observed only at a high alum dosage, the role of coagulation would be contaminant loading reduction. Results showed that both phenomena were important. Coagulation improved the membrane performance by changing particle characteristics at a low alum dosage. The improvement was achieved through both a change in particle characteristics and contaminant loading reduction at a high alum dosage. Particle size among various characteristics was found the most important for membrane fouling. Coagulation increased particle size, which led to a reduction of fouling. The beneficial effect from coagulation was observed at both fouling steps of pore blocking/adsorption and cake formation. Coagulation pretreatment was also beneficial for the improvement of the permeate quality in terms of organic matter.     

A pilot plant study for catalytic decomposition of PCDDs/PCDFs over supported chromium oxide catalysts

Chromium oxide catalysts supported on TiO₂ and Al₂O₃ were examined in a fixed-bed flow reactor system for the removal of PCE (perchloroethylene), a simulant of 2,3,7,8-TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin), and in a pilot plant employing actual flue gas from a sintering plant for the removal of PCDDs/PCDFs (poly-chlorinated dibenzo-dioxin/poly-chlorinated dibenzo-furan). The 12.5 wt.% chromium oxides supported on TiO₂ and Al₂O₃ revealed excellent stability and performance of PCE removal in the feed gas stream containing water vapor. In a pilot plant study, the catalysts washcoated on the honeycomb reactor revealed 93–95% of PCDDs/PCDFs removal activity over CrO_x/Al₂O₃-HC20 (CrO_x/Al₂O₃ catalyst washcoated on 20 cell-honeycomb), and more than 99% of the decomposition activity over CrO_x/TiO₂-HC20 (CrO_x/TiO₂ catalyst washcoated on 20 cell-honeycomb) at 325 °C and 5000 h⁻¹ of reactor space velocity without the de novo synthesis of PCDDs/PCDFs. In particular, CrO_x/TiO₂-HC20 showed 94% of PCDDs/PCDFs decomposition activity even at 280 °C reaction temperature. The catalyst also exhibited significant NO removal activity. The chromium oxide seems to be a promising catalyst for the removal of PCDDs/PCDFs and NO_x contained in the flue gas.