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Probability-based design charts for stone column-improved ground
Deb, Kousik,Majee, Anjan Techno-Press 2014 Geomechanics & engineering Vol.7 No.5
A simplified probability-based design charts for stone column-improved ground have been presented based on the unit cell approach. The undrained cohesion ($c_u$) and coefficient of radial consolidation ($c_r$) of the soft soil are taken as the most predominant random variables. The design charts are developed to estimate the diameter of the stone column or the spacing between the stone columns by employing a factored design value of $c_r$ and $c_u$ so as to satisfy a specific probability level of the target degree of consolidation and/or a target safe load that needs to be achieved in a specified timeframe. The design charts can be used by the practicing engineers to design the stone column-improved ground by considering consolidation and /or bearing capacity of the improved ground.
Deb Nath, Narayan Chandra,Choi, Seung Yo,Jeong, Hye Won,Lee, Jae-Joon,Park, Hyunwoong Elsevier 2016 Nano energy Vol.25 No.-
<P><B>Abstract</B></P> <P>A photoelectrochemical (PEC) cell composed of a WO<SUB>3</SUB>/dye-sensitized solar cell (WO<SUB>3</SUB>/DSSC) and copper oxide (Cu<SUB>x</SUB>O, where <I>x</I>=1 and 2) wire arrays as a dual-absorber photoanode and cathode, respectively, is demonstrated as a stand-alone, durable device for CO<SUB>2</SUB> photoconversion. The Cu<SUB>x</SUB>O wire arrays, which have high surface-to-volume ratios, exhibit promising electrocatalytic activity for CO<SUB>2</SUB> conversion to CO at Faradaic efficiencies of ~80% and ~60% at E=−0.2 and −0.4V <I>vs</I>. RHE, respectively, and H<SUB>2</SUB> production is minimized at a Faradaic efficiency <~20% in the potential range between −0.2 and −1.0V <I>vs</I>. RHE. The single-absorber cell of a WO<SUB>3</SUB> photoanode and Cu<SUB>x</SUB>O wire array cathode couple (WO<SUB>3</SUB>-Cu<SUB>x</SUB>O) requires a minimum overpotential of ~0.7V to drive CO<SUB>2</SUB> conversion. For stand-alone CO<SUB>2</SUB> conversion, a DSSC is coupled to the WO<SUB>3</SUB>-Cu<SUB>x</SUB>O system. In the dual-absorber cell (WO<SUB>3</SUB>/DSSC-Cu<SUB>x</SUB>O), the long-wave band (λ ><I>ca</I>. 450nm) passed through the semitransparent WO<SUB>3</SUB> film is absorbed by the dye-sensitized TiO<SUB>2</SUB> electrode of the DSSC. The WO<SUB>3</SUB>/DSSC-Cu<SUB>x</SUB>O shows a potential gain of ~0.7V and is able to successfully drive CO<SUB>2</SUB> conversion on Cu<SUB>x</SUB>O and simultaneously oxidize water on WO<SUB>3</SUB> without an external power supply. In this stand-alone system, the primary CO<SUB>2</SUB> conversion product is CO, with a solar-to-chemical energy efficiency of ~2.5%; H<SUB>2</SUB> and formate are obtained with energy efficiencies of 0.7% and 0.25%, respectively, in 5h (overall efficiency ~3.45%). Neither CO<SUB>2</SUB> conversion product nor H<SUB>2</SUB> is found using the single-absorber system.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Stand-alone photoelectrochemical cell for CO<SUB>2</SUB> conversion was designed. </LI> <LI> WO<SUB>3</SUB>/DSSC and copper oxide (Cu<SUB>x</SUB>O) wire arrays were coupled as a dual-absorber photoanode and cathode, respectively. </LI> <LI> In the dual-absorber cell, the long-wave band passed through the semitransparent WO<SUB>3</SUB> film is absorbed by DSSC. </LI> <LI> The primary CO<SUB>2</SUB> conversion product is CO, with an energy efficiency of ~2.5% (overall efficiency ~3.45%). </LI> <LI> Neither CO<SUB>2</SUB> conversion product nor H<SUB>2</SUB> is produced by the single-absorber system. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Bearing capacity of geotextile-reinforced sand with varying fine fraction
Deb, Kousik,Konai, Sanku Techno-Press 2014 Geomechanics & engineering Vol.6 No.1
Use of geotextile as reinforcement material to improve the weak soil is a popular method these days. Tensile strength of geotextile and the soil-geotextile interaction are the major factors which influence the improvement of the soil. Change in fine content within the sand can change the interface behavior between soil and geotextile. In the present paper, the bearing capacity of unreinforced and geotextile-reinforced sand with different percentages of fines has been studied. A series of model tests have been carried out and the load settlement curves are obtained. The ultimate load carrying capacity of unreinforced and reinforced sand with different percentages of fines is compared. The interface behavior of sand and geotextile with various percentages of fines is also studied. It is observed that sand having around 5% of fine is suitable or permissible for bearing capacity improvement due to the application of geosynthetic reinforcement. The effectiveness of the reinforcement in load carrying capacity improvement decreases due to the addition of excessive amount of fines.
DCT and DWT Based Robust Audio Watermarking Scheme for Copyright Protection
Deb, Kaushik,Rahman, Md. Ashikur,Sultana, Kazi Zakia,Sarker, Md. Iqbal Hasan,Chong, Ui-Pil The Korea Institute of Convergence Signal Processi 2014 융합신호처리학회 논문지 (JISPS) Vol.15 No.1
Digital watermarking techniques are attracting attention as a proper solution to protect copyright for multimedia data. This paper proposes a new audio watermarking method based on Discrete Cosine Transformation (DCT) and Discrete Wavelet Transformation (DWT) for copyright protection. In our proposed watermarking method, the original audio is transformed into DCT domain and divided into two parts. Synchronization code is applied on the signal in first part and 2 levels DWT domain is applied on the signal in second part. The absolute value of DWT coefficient is divided into arbitrary number of segments and calculates the energy of each segment and middle peak. Watermarks are then embedded into each middle peak. Watermarks are extracted by performing the inverse operation of watermark embedding process. Experimental results show that the hidden watermark data is robust to re-sampling, low-pass filtering, re-quantization, MP3 compression, cropping, echo addition, delay, and pitch shifting, amplitude change. Performance analysis of the proposed scheme shows low error probability rates.
Deb Nath, Narayan Chandra,Jeon, In-Yup,Ju, Myung Jong,Ansari, Sajid Ali,Baek, Jong-Beom,Lee, Jae-Joon Elsevier 2019 Carbon Vol.142 No.-
<P><B>Abstract</B></P> <P>Edge-carboxylated graphene nanoplatelets (<B>ECG</B>), prepared by a mechano-chemical reaction (or ball milling method) in the presence of dry ice, are eligible for an efficient electrode materials for electrochemical supercapacitors. <B>ECG</B> contained a higher content of edge-carboxylic groups with less structural defects, compared with the nitrogen-doped carboxylic graphene (<B>NGOOH</B>) prepared from the conventional solution-exfoliation of graphite. The structural defects level of <B>ECG</B> is <I>ca</I>. 16.2%, while it was <I>ca</I>. 48.9% for <B>NGOOH</B>. The edge-carboxylation increases the electroactive surface area, hydrophilicity and wettability of graphene without serious deterioration of the intrinsic properties <I>e.g</I>., chemical, mechanical and electronic properties. In result, it is more effective in enabling ion adsorption and rapid electrolyte diffusion within the pores of graphene which results in a significant increase of specific capacitance (<I>C</I> <SUB>sp</SUB>) to 365.72 F/g at a current density of 1 A/g, with a good charge–discharge property and rate capability for <B>ECG.</B> On the other hand, the <I>C</I> <SUB>sp</SUB> significantly decreases to <I>ca.</I> 175.05 F/g for <B>NGOOH</B>, as its high level of structural defects seriously affected its electronic properties.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Deb, Kaushik,Al-Seraj, Md. Sajib,Chong, Ui-Pil The Korea Institute of Convergence Signal Processi 2013 융합신호처리학회 논문지 (JISPS) Vol.14 No.1
A combined DWT and DCT based watermarking technique of low frequency watermarking with weighted correction is proposed. The DWT has excellent spatial localization, frequency spread and multi-resolution characteristics, which are similar to the theoretical models of the human visual system (HVS). The DCT based watermarking techniques offer compression while DWT based watermarking techniques offer scalability. These desirable properties are used in this combined watermarking technique. In the proposed method watermark bits are embedded in the low frequency band of each DCT block of selected DWT sub-band. The weighted correction is also used to improve the imperceptibility. The extracting procedure reverses the embedding operations without the reference of the original image. Compared with the similar approach by DCT based approach and DWT based approach, the experimental results show that the proposed algorithm apparently preserves superiori mage quality and robustness under various attacks such as JPEG compression, cropping, sharping, contrast adjustments and so on.