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Improvement in DRX Power Saving for Non-real-time Traffic in LTE
Mohammad Tawhid Kawser,Mohammad Rakibul Islam,Khondoker Ziaul Islam,Mohammad Atiqul Islam,Mohammad Mehadi Hassan,Zobayer Ahmed,Rafid Hasan 한국전자통신연구원 2016 ETRI Journal Vol.38 No.4
A discontinuous reception (DRX) operation is included in the Long Term Evolution (LTE) system to achieve power saving and prolonged battery life of the user equipment. An improvement in DRX power saving usually leads to a potential increase in the packet delay. An optimum DRX configuration depends on the current traffic, which is not easy to estimate accurately, particularly for non-real-time applications. In this paper, we propose a novel way to vary the DRX cycle length, avoiding a continuous estimation of the data traffic when only non-real-time applications are running with no active real-time applications. Because a small delay in non-real-time traffic does not essentially impact the user’s experience adversely, we deliberately allow a limited amount of delay in our proposal to attain a significant improvement in power saving. Our proposal also improves the delay in service resumption after a long period of inactivity. We use a stochastic analysis assuming an M/G/1 queue to validate this improvement.
A Dream into Reality: Smart Internet of Things
모하메드마타하리이슬람 ( Motaharul Islam ),알-아민후세인 ( Al Amin Hossain ),사비르하산 ( Sabbir Hasan ),모하마드아잠 ( Mohammad Aazam ),마우리시오알레 ( Mauricio Alejandro ) 한국정보처리학회 2013 한국정보처리학회 학술대회논문집 Vol.20 No.1
Once upon a time people dreamt for a connected world. But most of the people consider dream as simple as a dream. But when this dream come into reality, the dreamer sometimes alive and sometimes not. But the later generations get outcome from the visionary dream of the former. This is the way of life. If we consider the whole world as a cyber physical system, if everything connects everything, how do we feel then? It is the smart Internet of things that may connect the whole world. This paper addresses few challenges and opportunities of this envisioned connected World. We identify different systems as cyber physical system and it ultimately contribute to the cloud infrastructure.
Interactive Study of Electroreflectance and Photocurrent Spectra in InGaN/GaN-Based Blue LEDs
Islam, Abu Bashar Mohammad Hamidul,Dong-Soo Shin,Jong-In Shim IEEE 2017 IEEE journal of quantum electronics Vol.53 No.5
<P>We experimentally and theoretically investigate the relationship between the electroreflectance (ER) and photocurrent (PC) spectra, and how they can be utilized to estimate the flat-band voltage and the bandgap energy of the InGaN/GaN-based quantum-well (QW) structure in blue lighte-mitting diodes. With theoretical modeling of ER and PC spectra, we calculate the changes in both the refractive index (Delta n) and optical absorption (Delta alpha) spectra from experimental ER and PC data by using the Kramers-Kronig relation. Then, we compare Delta n (or Delta alpha) spectra obtained differently from the ER and PC data and try to comprehend their physical meanings interactively. From these combined studies, we propose an exact method of determining the flat-band voltage, the piezoelectric field, the emission energy, the effective bandgap energy, and the Stokes shift of a QW structure under the quantum-confined Stark effect (QCSE).</P>
Islam, Mohammad S.,Do, Jeongyun,Kim, Dookie Techno-Press 2018 Smart Structures and Systems, An International Jou Vol.21 No.2
In this inquisition, a passive damper namely Stockbridge Damper (SBD) has been introduced to the field of vibration control of Offshore Wind Turbine (OWT) to reduce the earthquake excitations. The dynamic responses of the structure have been analyzed for three recorded earthquakes and the responses have been assessed. To find an optimum SBD, the parameters of damper have been optimized using Response Surface Methodology (RSM) based on Box-Behnken Design (BBD) and Particle Swarm Optimization (PSO). The influence of the design variables of SBD such as the diameter of messenger cable, the length of messenger cable and logarithmic decrement of the damping has been investigated through response variables such as maximum displacement, RMS displacement and frequency amplitude of structure under an artificially generated white noise. After that, the structure with optimized and non-optimized damper has been analyzed with under the same earthquakes. Moreover, the comparative results show that the structure with optimized damper is 11.78%, 18.71%, 11.6% and 7.77%, 7.01%, 10.23% more effective than the structure with non-optimized damper with respect to the displacement and frequency response under the earthquakes. The results show that the SBD can obviously affect the characteristics of the vibration of the OWT and RSM based on BBD and PSO approach can provide an optimum damper.
Self-assembly of a liquid crystal ABA triblock copolymer in a nematic liquid crystal solvent
Islam, Mohammad Tariqul,Kamal, Tahseen,Shin, Taegyu,Seong, Baekseok,Park, Soo-Young Elsevier 2014 Polymer Vol.55 No.16
<P><B>Abstract</B></P> <P>An ABA type triblock copolymer, consisting of liquid crystalline polymer (LCP, poly(4-cyanobiphenyl-4-oxyundecylacrylate)) ‘A’ end blocks and a deuterated polystyrene (dPS) ‘B’ mid block (LCP–dPS–LCP) was successfully synthesized by atom transfer radical polymerization (ATRP). The number average molecular weight (<I>M</I> <SUB>n</SUB>) of LCP–dPS–LCP was LCP (7.1 K)–dPS (19.4 K)–LCP (7.1 K) with a polydispersity index (PDI) of 1.41. LCP–dPS–LCP was self-assembled in a nematic liquid crystal solvent of 4-pentyl-4′-cyanobiphenyl (5CB) into spherical micelles with a LCP corona and a dPS core, in which dPS was folded to produce a V-shape structure. Micellar structures of LCP–dPS–LCP in 5CB were examined by small angle neutron scattering at various block copolymer concentrations and temperatures using a curve fitting method. The critical micelle concentration was 0.25 wt% and the self-assembled micelles dissociated into unimers at 33 °C, which is lower than the nematic to isotropic transition temperature (<I>T</I> <SUB>ni</SUB>) of 5CB (36 °C). The entropic penalty imposed on dPS by the ordered nematic state of the 5CB solvent caused phase separation of the flexible dPS block to form micelles, which vanished above the <I>T</I> <SUB>ni</SUB> of the 5CB solvent. Magnetic field-induced global orientation of 5CB revealed the structure of the dPS core of the micelle to be prolate (an elongated sphere) oriented with its long axis along the direction of the applied magnetic field.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Islam, Mohammad Nazrul,Park, Keum-Joo,Yoon, Hyung-Sun Korean Society for Agricultural Machinery 2012 바이오시스템공학 Vol.37 No.2
Purpose: Methane production potential in aerobic digestion was assessed according to feed to inoculum (F/I) ratio for food waste only, and mixing ratio of two materials for food waste and swine manure to give a basic data for the design of anaerobic digestion system. Methods: Anaerbic digestion test was performed using a lab scale batch reactor at $35^{\circ}C$ for six different feed to inoculum (F/I) ratios (0.50, 0.72, 1.14, 1.50, 2.14 and 3.41), three food waste to swine manure ratios (100:0, 60:40 and 40:60) with two different loading concentrations (10g VS/L and 30g VS/L). Results: For food waste only, the highest biogas yield of 1008 mL/gVS was obtained at 0.50 of F/I. For the co-digestion of food waste and swine manure mixture, the highest biogas yield of 1148 mL/gVS was obtained at a mixing ratio of 40:60 with loading concentration of 10g VS/L. Conclusions: F/I ratio for the food waste only, mixing ratio of food waste and swine manure, and co-substrate loading rate affected the biogas production rate. For the low loading rate, there was not so much difference according to the mixing ratio of food waste and swine manure, but for the high loading rate higher biogas yield was acquired for the co-digestion of food waste and swine manure than for the food waste alone (mixing ratio, 100:0).