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Dielectric and Electromechanical Properties of Zr-Doped BNT-ST Lead-Free Piezoelectric Ceramics
Amir Ullah,Mateen Ullah,Aman Ullah,A. V. Trukhanov,Ghulam Saddiq,Burhan Ullah,Aurang Zeb,Saeed Ullah Jan,김일원 한국물리학회 2019 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.74 No.6
0.72(Bi$_{0.5}$Na$_{0.5}$)Ti$_{(1-x)}$Zr$_x$O$_3$-0.28SrTiO$_3$ (BNTZ-ST) with $x$ = 0.00, 0.01, 0.02 and 0.03 were produced using a solid solution reaction procedure. Results from the X-ray diffraction (XRD) analysis showed the presence of a perovskite structure with cubic symmetry for all samples. Surface analysis was completed using field emission scanning electron microscopy (FE-SEM), and the grain size was found to decrease slightly with increasing Zr doping. The grain morphology was primarily rectangular, but morphed into a rounder shape with increases in Zr. In a dielectric constant study, the depolarization temperature was found to decrease with increasing Zr$^{+4}$ content and increasing frequency. The strain was found to be 0.34\% for the undoped samples with an equivalent dynamic strain ($S_{max}/E_{max}$) of 618 pm/V, without negative strain. However, the strain decreased slightly and hysteresis loops become slim and more symmetric, attaining a relaxor ferroelectric behavior with increasing Zr content.
Integrated Tracking and Accident Avoidance System for Mobile Robots
Irfan Ullah,Furqan Ullah,Qurban Ullah,신서용 제어·로봇·시스템학회 2013 International Journal of Control, Automation, and Vol.11 No.6
In the intelligent transportation field, various accident avoidance techniques have been applied. One of the most common issues with these is the collision, which remains an unsolved problem. To this end, we developed a Collision Warning and Avoidance System (CWAS), which was implemented in the wheeled mobile robot. Path planning is crucial for a mobile robot to perform a given task correctly. Here, a tracking system for mobile robots that follow an object is presented. Thus, we implemented an integrated tracking system and CWAS in a mobile robot. Both systems can be activated independently. Using the CWAS, the robot is controlled through a remotely controlled device, and collision warning and avoidance functions are performed. Using the tracking system, the robot performs tasks autonomously and maintains a constant distance from the followed object. Information on the surroundings is obtained through range sensors, and the control functions are performed through the microcontroller. The front, left, and right sensors are activated to track the object, and all the sensors are used for the CWAS. The proposed system was tested using the binary logic controller and the Fuzzy Logic Controller (FLC). The efficiency of the robot was improved by increasing the smoothness of motion via the FLC, achieving accuracy in tracking and increasing the safety of the CWAS. Finally, simulations and experimental outcomes have shown the usefulness of the system.
Effects of CPEC on the Economy of China and Pakistan
Sadiq Ullah(Sadiq Ullah ),Mumtaz Alam(Mumtaz Alam ),Zulfiqar Ali Baig(Zulfiqar Ali Baig ) 아시아사회과학학회 2022 Jornal of Asia Social Science Vol.8 No.3
CPEC is a huge investment that will bring prosperity and will heal the economic condition of Pakistan. It will also give China the shortest proximity to the rest of the world. It's a project which will benefit both of the countries as well as Europe and the Gulf. Descriptive analysis is used in this research study to investigate the effects of CPEC on Pakistan and China's economy. Diverse literature was found on this topic and is cited in the literature part of this research study. This study shows that Pakistan and China both of the countries will be better off and will achieve good economic results. Pakistan will get the maximum benefit from CPEC because its infrastructure and energy structure is less developed. And by the injection of this massive CPEC project, the Pakistani economy will boost up, and the mutual trade between China and Pakistan will be enhanced. GDP growth and welfare position of Pakistan will take more benefit from CPEC than China. Chinese export of non-agricultural products will increase more than the Chinese export of agricultural products. While in the case of Pakistani exports, the situation is the opposite one. Agricultural exports will be increased more than the increase in non-agricultural exports of Pakistan.
Mateen Ullah,Amir Ullah,Hidayat Ullah Khan,Imtiaz Ahmad,김일원 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.76 No.2
Piezoelectric ceramics (Bi0.5Na0.5)0.935Ba0.065Ti1-x(Al0.5Nb0.5)xO3 (BNBT-AN) have been synthesized for x = 0, 0.010, 0.015, 0.020, 0.025, and 0.030 through simple solid state reaction technique. Synthesis and sintering of all the systems were successful as single phase was obtained through out. This work explains the influence of AN on morphology, phase structure, electrical and electromechanical characteristics of the parent BNBT matrix. All compositions were single phase perovskites by X-ray diffraction (XRD), that could be confirmed as the tetragonal, P4/m, and rhombohedral, R3c, mixed structures. Tetragonality was increased with increase in the AN content. With similar modification, dynamic piezoelectric constant d*33 (= Smax/Emax) was increased monotonically gaining a highest value of 354 pm/V corresponding to x = 0.030. The overall increase was found in remnant polarization (Pr) for all the systems except for the one with x = 0.030. Maximum Pr, 30.6 μC/cm^2, was noted for x = 0.025. This phenomenon was also accompanied by a persistent decrease in coercive field Ec, from 28.0 kV/cm for undoped to 14.5 kV/cm for 3 mol%. The ceramics were signified with encouraging electrical properties.
Safi Ullah Khan,Naimat Ullah Khan,Asad Ullah 한국증권학회 2021 Asia-Pacific Journal of Financial Studies Vol.50 No.2
We investigate whether cross-country differences in the legal system influence demand-side credit constraints. We explore the notion of discouraged borrowers — firms that choose not to apply for bank credit because they anticipate rejection. Employing survey data from 46 economies, we find that rapid and less costly court proceedings, lower procedural complexity in court processes, and higher recovery rates under bankruptcy lead to the lower likelihood of borrower discouragement. These results are more pronounced in countries with strong creditor protections in relation to company reorganization and liquidation. The results corroborate the supply-side view that strong creditor rights and their efficient enforceability alleviate banks’ participation constraints in the loan market, thereby encouraging small and medium-sized enterprises to apply for credit in the first place. We also find that differences in institutional settings, such as higher regulatory quality, better control of corruption, and the rule of law, lead to lower rates of credit self-rationing in the loan market.
Incipient ferroelectricity of AgTaO3 and ferroelectric nature of (Li0.008Ag0.992)TaO3
Khan Hidayat Ullah,Ullah Amir,Sualiheen Karishma,Ahmad Imtiaz,Ullah Mateen 한국물리학회 2021 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.79 No.9
AgTaO3 (AT) and ( Li0.008Ag0.992)TaO3 (LAT-0.8) compositions have been fabricated successfully via solid-state reaction (SSR) route. Phase purity of both the calcined powder and crushed sintered pellet was confirmed with XRD peaks which were indexed according to the rhombohedral structure with R3c∕R3c. The smooth hysteretic behavior of the LAT-0.8 system evidenced unlocking of the hidden ferroelectricity of AT. This phenomenon confirmed the incipient ferroelectric/quantum paraelectric nature of AT. So far, the triggering of ferroelectricity with 0.8% Li modification in AT has not been reported in the literature. A fair ferroelectric response of AT and LAT-0.8 at − 20 °C was obtained.
Fathi Etaher Elbakoush,Qudrat Ullah Khan,Mati Ullah,Arif Ullah,Afaq Ullah Khan,Javed Khan,Asra Iftikhar 한국전기전자재료학회 2021 Transactions on Electrical and Electronic Material Vol.22 No.6
The carbonization performance of the iron-containing carbon film resulting from polyimide was examined, Polyimide/Fe composite films were prepared from Iron (III) 2,4-pentanedionate (Fe(acac)) and poly(amic acid) (PAA) based on ODA and PMDA via a solution process in DMAC, followed by carbonization the polyimide film at a temperature range of 600–1600 °C. The organized polyimide/Fe combined fi lms were characterized using a scanning electron microscope (SEM), and thermogravimetric analysis (TGA), X-ray diffraction (XRD), and Raman. The formation of Fe particles and the synthesis of polyimide (PMDA/ODA) in the polyimide matrix is confirmed by FTIR results. Meantime, in the polyimide matrix, Fe particles were well spread which were showed by the SEM images. Kinetic parameters and thermal stability of the degradation methods for the organized polyimide/Fe combined films were examined in N 2 environment by TGA. The results have shown that the values of the calculated activation energies and thermal stability increased of the (Fe (acac)) the activation energy and loading also different with the weight-loss rate for all compositions.
Throughput and delay limits of chirp spread spectrum‐based IEEE 802.15.4a
Ullah, Niamat,Sanaullah Chowdhury, M.,Khan, Pervez,Ullah, Sana,Kwak, Kyung Sup Wiley 2012 International Journal of Communication Systems Vol. No.
<P><B>SUMMARY</B></P><P>The IEEE 802.15.4 standard is designed to provide a low‐power, low data rate protocol offering a high reliability. As an amendment to this standard, IEEE 802.15.4a introduces new options for physical layer to enable precision ranging. In this work, we analyzed the theoretical throughput and delay bounds of the unslotted version of chirp spread spectrum PHY‐based 802.15.4a. The formulae for transmission between one sender and one receiver for an ideal channel with no transmission errors are given. The throughput and delay bounds are derived for different frequency bands and data rates. Additionally, to measure spectral utilization, we measured the bandwidth efficiency for both the standards. We also compared our results with IEEE 802.15.4. The comparative analysis concludes that the performance of 802.15.4a exceeds 802.15.4 in terms of throughput and delay. The analytical results of throughput are verified by computer simulations. Copyright © 2011 John Wiley & Sons, Ltd.</P>