Troubleshooting of Handover Problems in 900 MHz for Speech Quality

Although Long-term Evolution (LTE) technology has currently being used in data and voice transmission, reserved frequency bands for GSM is still in use due to its strengthen against multipath fading and it provides wider coverage area. Poor coverage problems caused by low signal level directly reduce network performance and cause undesirable cases for voice transmission. The aim of this study is first to solve handover (HO) problems due to the low signal quality and bad speech quality by hardware configuration and changing optimization parameters in detail as a novelty. The second is to examine the KPI values of the test region where HO problems have been solved and to determine whether the network contributed to the network quality. Offered method has made the network having following improvements; the value of RxQual drops from 0.61 to 0.57, number of failure in random access channel (RACH) drops down from 12 to 2, the number of failure in SDCCH drops down from 6 to 2, the total number of blocked calls from 18 to 4, and the number of dropped calls drops down to 2 from 5. Another criterion of the network quality the average for both uplink and downlink mean opinion score (MOS) value of region increased from 3.51 to 3.86. Also CSSR has been increased from 94.43 to 97.82% and HO success rate has been reached from 93.56 to 99.13%.

     

Sorption and Preconcentration of Vanadium,Chromium, Manganese,and Lead on Silica Gel Modified with (3‐Mercaptopropyl) Trimethoxysilane

Abstract

3‐mercaptopropyltrimethoxysilane, (CH₃O)₃SiCH₂CH₂CH₂SH, loaded on silica gel was used as a preconcentration sorbent for V, Cr, Mn and Pb prior to their determination by graphite furnace atomic absorption spetrometry (GFAAS). Surface characteristics and surface area of the silica gel before and after chemical modification were determined by elemental analysis. The retention and recovery of the analyte elements were studied by applying batch and column techniques. The experimental parameters, such as the effect of pH of the sample, shaking time in batch technique, flow rate of the eluent, the concentration of acid solution in the column section, and the amount of silica on retention and elution have been investigated. All elements were quantitatively (≥90%) recovered in the batch technique with R.S.D. values of 3.0 for vanadium, 1.8 for chromium, 1.7 for manganese, and 0.4 for lead. The same recoveries were obtained in the column techniques for all elements, while manganese in sea water could not be succesfully recovered. Detection limits of the method for vanadium, chromium, manganese, and lead are 1.1, 1.4, 1.3, and 0.8 ng, respectively.     

DESIGN OF A LOW-COST MICROCONTROLLER-BASED FUNCTIONAL ELECTRONIC STIMULATION DEVICE FOR DROP FOOT CORRECTION

Correction of drop foot is normally achieved by electrical stimulation of the common peroneal nerve by sending a series of pulses at a given frequency and duration. This article presents the design of a low-cost, programmable, portable, and high performance stimulator, designed at the Near East University. The stimulator, called the NEU-Stim, has been designed to correct the drop foot problems. For this purpose, a foot sensor, microcontroller, and electrodes are used in the design of the stimulator. The frequency, duty cycle, and the amplitude of the output waveform can easily be controlled using switches. The device is currently in experimental stage, and because of its low-cost it should find applications in developing countries after it has been completely assessed. Preliminary results on patients have shown that the device can correct the drop foot, and help patients to walk faster and more comfortably.     

Adaptive architectures for control of uncertain dynamical systems with actuator and unmodeled dynamics

In adaptive control of uncertain dynamical systems, it is well known that the presence of actuator and/or unmodeled dynamics in feedback loops can yield to unstable closed‐loop system trajectories. Motivated by this standpoint, this paper focuses on the analysis and synthesis of multiple adaptive architectures for control of uncertain dynamical systems with both actuator and unmodeled dynamics. Specifically, we first analyze model reference adaptive control architectures with standard, hedging‐based, and expanded reference models for this class of uncertain dynamical systems and develop sufficient stability conditions. We then synthesize a robustifying term for the latter architecture and analytically show that this term can allow for a relaxed sufficient stability condition. The proposed theoretical treatments involve Lyapunov stability theory, linear matrix inequalities, and matrix mathematics. Finally, we compare the resulting sufficient stability conditions of the considered adaptive control architectures on a benchmark mechanical system subject to actuator and unmodeled dynamics.     

The investigation of structural and magnetic properties of Er2−xCoxO3 nano-oxides

Journal of Materials Science: Materials in Electronics - The sol–gel technique was used to synthesize Er2?xCoxO3 (0.0?≤?x?≤?0.30) mixed oxides to...     

Learning Control of Robot Manipulators in Task Space

Two important properties of industrial tasks performed by robot manipulators, namely, periodicity (i.e., repetitive nature) of the task and the need for the task to be performed by the end‐effector, motivated this work. Not being able to utilize the robot manipulator dynamics due to uncertainties complicated the control design. In a seemingly novel departure from the existing works in the literature, the tracking problem is formulated in the task space and the control input torque is aimed to decrease the task space tracking error directly without making use of inverse kinematics at the position level. A repetitive learning controller is designed which “learns” the overall uncertainties in the robot manipulator dynamics. The stability of the closed‐loop system and asymptotic end‐effector tracking of a periodic desired trajectory are guaranteed via Lyapunov based analysis methods. Experiments performed on an in‐house developed robot manipulator are presented to illustrate the performance and viability of the proposed controller.     

Assessment of trace element levels in Rhododendron honeys of Black Sea Region, Turkey

Rhododendron and multi-flower honeys obtained from Black Sea Region of Turkey (12 Rhododendron and 8 multi-flower honeys) were studied to determine the presence of the 14 trace elements such as Cu, Cd, Pb, Co, Cr, Ni, Al, Se, Zn, Mn, Fe, K, Ca and Mg. Trace element determination was performed by atomic absorption spectrometry (AAS) after microwave digestion. The results revealed that Rhododendron honeys exhibited higher concentrations of Cu, Co, Cr, Ni, Se, Zn, Ca and Mg but lower concentrations of Al, Mn, Fe and K than in the multi-flower honeys. Trace element levels in analyzed honey samples were generally lower than literature values.     

A comparative study of linear and non-linear regression analysis for ammonium exchange by clinoptilolite zeolite

Ammonium ion exchange from aqueous solution using clinoptilolite zeolite was investigated at laboratory scale. Batch experimental studies were conducted to evaluate the effect of various parameters such as pH, zeolite dosage, contact time, initial ammonium concentration and temperature. Freundlich and Langmuir isotherm models and pseudo-second-order model were fitted to experimental data. Linear and non-linear regression methods were compared to determine the best fitting of isotherm and kinetic model to experimental data. The rate limiting mechanism of ammonium uptake by zeolite was determined as chemical exchange. Non-linear regression has better performance for analyzing experimental data and Freundlich model was better than Langmuir to represent equilibrium data.