007265   PATIL K, LAAD M, KAMBLE A, LAAD S (Computer Engineering Dep, Vishwakarma Institute of Information Technology, Pune– 411 048) : A consumer-based smart home with indoor air quality monitoring system. IETE J Res 2019, 65(6), 758-70.

Nowadays, home automation has become a popular trend and the demand for smart homes is rising with consumers being increasingly aware of the new technologies developed in the field of automation. While designing a home automation system, the parameters such as cost, compactness, energy efficiency, reliability, real-time implementation, and appliance scheduling play prime importance. With increasing pollution, respiratory diseases are on the rise and there is a strong need to develop a smart home system which is capable of monitoring healthy environmental conditions for its users. This research study proposes a smart system that uses a renewable source of energy, monitors and controls the overall power consumption of the home, and keeps a check on the healthy environmental conditions by measuring the level of oxygen thereby alarming when it falls below the safe limit. This research paper provides analysis of indoor air quality and health system. In addition, it measures indoor air quality using two factors: health and comfort. The proposed model is compact, cost-effective, energy-efficient, and provides a health-smart home system to the consumer.

14 illus, 39 ref

007254   KALIYATH Y, LAXMINIDHI T (Electronics and Communication Engineering Dep, National Institute of Technology Karnataka, Mangalore, Karnataka) : A 1.8 V 8.62 µW inverter-based gain-boosted OTA with 109.3 dB dc gain for SC circuits. IETE J Res 2019, 65(6), 749-57.

This paper presents a low-power inverter-based gain-boosted operational transconductance amplifier (OTA) for switched capacitor (SC) circuits operating at higher supply voltage ( > 1 V). The proposed OTA is implemented using UMC 180 nm CMOS technology with a supply voltage of 1.8 V and it offers a high dc gain with a unity gain bandwidth (UGB) suitable for audio applications. All the transistors of the proposed OTA are operated in sub-threshold region to minimize the power consumption. Gain-boosting technique is employed to achieve a higher dc gain. The post-layout simulations demonstrate the robust performance of the proposed OTA, which delivers a high dc gain of 109.3 dB and a UGB of 5.29 MHz at 81^◦ phase margin (PM) with a capacitive load of 2.5 pF for a typical process corner at room temperature (27 ^◦C). The proposed OTA draws a quiescent current (IQ) of 4.79 µA, resulting in a power consumption of 8.62 µW.

13 illus, 8 tables, 28 ref

007261   MAHAPATRA M K (Chemical Engineering Dep, National Institute of Technology, Rourkela- 769 008, Email: manojmahapatra2010@gmail.com) : Cogeneration: An innovative approach to generate multiple forms of energy from a single source. Everyman's Sci 2019, 54(4), 217-22.

Energy is a must-have thing in the current era and is predominantly in two forms like electrical energy and thermal energy. Generating those two forms of energy separately results in enhanced global pollution and declinement of efficiency. Cogeneration is an alternative solution to yield both forms of energy with lesser pollution, from just a single energy source. cogeneration systems are flexible in terms of application in various industrial sectors owing to their types and energy output. The cogeneration systems are cost-effective not only because of the lesser amount of fuel consumption but also due to the revenue generation by selling the surplus productions to the nearby power grids.

4 illus, 5 ref

007281   YU Y, YUE Y (Xinxiang Medical Univ, Xinxiang, China) : The motion image recognition method based on LZ complexity analysis. Biomed Res 2019, 30(6), 1-5.

In this study, the LZ complexity of the nonlinear analysis method was used as the reference to process the EEG before and after the motor imagery task, and the results were compared statistically. It was concluded that the LZ complexity could be used as the feature vector to distinguish the hand grip and stretching in the whole EEG channel, and some of the EEG channels could be used in some bands. To distinguish whether there is movement; theta band can very well distinguish between the two imaginary movements; and also analyzed in motion (or imagination) before the relative calm state is not statistically different. These conclusions can provide a theoretical basis for subsequent brain computer interface experiments.

9 illus, 11 ref

007252   JAVED R, RAHIM M S M, SABA T, RASHID M (Engineering Dep, Teknologi Malaysia Univ, Johor Bahru, Malaysia) : Region-based active contour JSEG fusion technique for skin lesion segmentation from dermoscopic images. Biomed Res 2019, 30(6), 1-10.

Malignant melanoma is one of the most aggressive forms of skin cancer which must be necessary to be diagnosed at the initial stage for effective treatment. Melanoma affects the patient life even it can become a reason of death if its diagnosis is not accomplished on time. Through a rough pigment network and some suspicious signs can be helpful for diagnosis the melanoma from dermoscopic images. According to the clinical studies, for dermatologists, it is quite difficult to identify these signs at the initial stage of melanoma. So, it is important to propose an automated system which can efficiently be identified and differentiate between benign and malignant melanoma. The main focus of this research article is to improve the skin lesion segmentation from low contrast and under/ over segmented dermoscopic images through fusing the region based active contour method with JSEG method. The proposed fused segmentation technique gain 95.3 % accuracy and through our proposed feature vector the Gaussian classifier achieved the promising results as sensitivity 97.7 %, specificity 96.7 %, and accuracy 97.5 % with handling the special dermoscopic image cases which are comparatively much better than numerous exiting techniques.

6 illus, 9 tables, 40 ref

007247   DARWICH A, SHASH M, ALI A, NAZHA H, MAROUF A, ABBAS W (Biomedical Engineering Dep, Al-Andalus Univ for Medical Sciences, Tartous, Syria) : Numerical study of the influence of ultra-thin veneer materials and its thickness on their biomechanical behavior. Biomed Res 2019, 30(6), 920-3.

This study investigated the influence of ultra-thin veneer materials and its thickness on their biomechanical behavior using the 3D finite element method to find out which of all these models have a better performance. The distribution of stresses in the models was studied when composite resin and feldspathic porcelain were used in ultra-thin veneers with thickness of 0.2 mm and 0.3 mm under static loads. The results showed that the use of composite resin in the preparation of veneer of 0.2 mm in thickness reduces the maximum stresses by 65.24 % at least compared to feldspathic porcelain, and it reduces the maximum stresses by 56.28 % at least compared to feldspathic porcelain in veneer with thickness of 0.3 mm. The results showed also that the use of composite resin ultra-thin veneer with thickness of 0.2 mm reduces the maximum stresses by 49.48 % at least compared to veneer with thickness of 0.3 mm, and the using of feldspathic porcelain ultra-thin veneer with thickness of 0.2 mm reduces the maximum stresses by 36.46 % at least compared to veneer with thickness of 0.3 mm. Therefore, it is recommended to use composite resin ultra-thin veneer with thickness of 0.2 mm as it reduces induced stresses, which improves the stability and durability of veneers and prolong its lifespan.

5 illus, 3 tables, 30 ref

007246   DARWICH A, ABOUD K, ALI S, ABBAS W (Biomedical Engineering Dep, Al-Andalus Univ for Medical Sciences, Tartous, Syria) : Comparison of several digital techniques for electroencephalography processing. Biomed Res 2019, 30(6), 887-94.

Most biological signals, whether they are muscle signals, brain signals or voice commands, are random and unending in their initial form. They are processed and filtered from the noise in the first stage and then classified, analyzed and extracted the required features of it in the second stage. In this study, the brain signals of a healthy person were captured according to a clinical protocol prepared for the purpose of the study, which is two consecutive blinks separated by 5 seconds rest and then a set of digital filters were used to analyze and classify these signals in order to obtain control from them. As a result, it was found that the use of Fourier transform is not feasible with biological signals because it is not cyclical signals. The use of short time Fourier transform can be a solution to this, but it is flawed by the loss of some frequency samples due to the adoption of fixed window technology and then the use of wavelet transform which depends on the variable window, but it has a large number of out-of-band frequencies. Ultimately, the intermittent discrete wavelet transform was used which provided the most accurate results and we were able to issue the appropriate control command.

11 illus, 25 ref

007280   YEWLE N, SWAIN K, MANN S, CHANDRASEKAR V, KALNAR Y (Agricultural Engineering Dep, Visva-Bharati Central Univ, Shantiniketan-731 235, Email: sandeep_mann76@yahoo.com) : Effect of polishing on chemical and engineering properties of yellow and black turmeric. Ann Phytomed 2019, 8(2), 85-92.

Effect of polishing on chemical and engineering properties of yellow and black turmeric rhizomes was studied and reported. The percentage of moisture content, protein, fat, carbohydrate, pH and curcumin of fresh and polished yellow turmeric were found to be 60.23, 1.30, 0.78, 34.04, 6.47 and 2.19; and 12.3, 1.20, 1.28 %, 76.3, 6.28 and 4.26; respectively. Similarly, for fresh and polished black turmeric, percentage of moisture content, protein, fat, carbohydrate, pH and Curcumin per cent of fresh and polished was found to be 13.47, 0.69, 0.67, 80.8, 5.52 and 0.31; and 8.11, 0.93, 0.56, 83.38, 5.96 and 0.45, respectively. Physical properties like arithmetic mean diameter, geometric mean diameter, sphericity, aspect ratio, and surface area of fresh and polished yellow turmeric were found to be 41.85 mm, 37.73 mm, 56.29, 51.29, and 4455.07 mm² ; and 33.69, 27.81, 44.72, 40.36, and 2429.93 mm² , respectively. Similarly, for fresh and polished black turmeric, the arithmetic mean diameter, geometric mean diameter, sphericity, aspect ratio, and surface area were found to be 39.56, 36.17, 56.93, 49.59 and 4109 mm² ; and 26.90, 21.29, 39.57, 27.45 and 1423 mm² , respectively. Engineering properties like bulk density, true density, porosity and frictional properties of angle of repose of fresh and polished yellow turmeric were found to be 810 kg/ m3 , 1780 kg/m³ , 99.54%, and 42.510; and 663.33 kg/m³ , 1658 kg/m³ , 99.34%, and 31.210, respectively. Similarly, for fresh and polished black turmeric, the bulk density, true density, porosity, and frictional properties of angle of repose were found to be 802 kg/m³ , 1966 kg/m³ , 99.59%, and 39.680; and 696 kg/m³ ,1560 kg/m³ , 99.53% and 33.470, respectively. The results indicated that polishing affected the chemical and engineering properties of yellow and black turmeric rhizomes.

15 illus, 2 tables, 42 ref

006061   FINOT C, RIGNEAULT H (Bourgogne-Franche-Comté Univ, Dijon Cedex, France, Email: christophe.finot@u-bourgogne.fr) : Arago spot formation in the time domain. J Opt 2019, 21(10), 105504.

Using the space-time duality, we theoretically and experimentally revisit the Arago spot formation in the time domain and explore the temporal emergence of a bright spot in the time shadow of an initial waveform. We describe the linear regime of propagation using Fresnel's integrals and show that in the presence of Kerr nonlinearity the Arago spot formation is affected depending on the sign of the dispersion. We finally confirm experimentally the Arago spot formation in the time domain using a telecommunication optical fiber platform.

9 illus, 41 ref

006065   KHAN M I, ALI T, ALI H, ZUBAIR M, AHMAD I, SHAFIQ M, AHMAD P, REHMAN F, SAEED Y (Physics Dep, Abbottabad Univ of Science and Technology, Havelian, Pakistan, Email: yamanuom@gmail.com) : Control of the faraday rotation via electromagnetically induced transparency medium and graphene metasurfaces. J Opt 2019, 21(10), 105401.

We investigate theoretically the control over Faraday rotation via an electromagnetically induced transparency medium (EIT) and graphene metasurfaces. The Faraday rotation of the light pulse is enhanced with increased probe field detuning. The increasing strength of the magnetic field enhances the rotation of the polarization plane and shifts its zero crossing at a higher frequency. The increase in the chemical potential rotates the polarization plane of the light pulse propagating through the system at low frequency. The periodic arrangement of disks on a graphene metasurface enhances the Faraday rotation of the light pulse and shifts the zero crossing relatively at a low frequency. The chemical potential, magnetic field and periodic length of disks can be used to control the Faraday rotation of light pulses at the desired frequency.

7 illus, 34 ref

006075   VU T, RAZANSKY D, YAO J (Biomedical Engineering Dep, Duke Univ, Durham, United States of America, Email: daniel.razansky@uzh.ch) : Listening to tissues with new light: Recent technological advances in photoacoustic imaging. J Opt 2019, 21(10), 103001.

Photoacoustic tomography (PAT), or optoacoustic tomography, has achieved remarkable progress in the past decade, benefiting from the joint developments in optics, acoustics, chemistry, computing and mathematics. Unlike pure optical or ultrasound imaging, PAT can provide unique optical absorption contrast as well as widely scalable spatial resolution, penetration depth and imaging speed. Moreover, PAT has inherent sensitivity to tissue’s functional, molecular, and metabolic state. With these merits, PAT has been applied in a wide range of life science disciplines, and has enabled biomedical research unattainable by other imaging methods. This review article aims at introducing state-of-the-art PAT technologies and their representative applications. The focus is on recent technological breakthroughs in structural, functional, molecular PAT, including super-resolution imaging, real-time smallanimal whole-body imaging, and high-sensitivity functional/molecular imaging. We also discuss the remaining challenges in PAT and envisioned opportunities.

5 illus, 1 table, 279 ref

006078   XING Z, WANG X, LOU S, ZHANG W, YAN S, TANG Z (Beijing Jiaotong Univ, Beijing- 100 044, People’s Republic of China, Email: 17111023@bjtu.edu.cn) : Bend-resistant side-leakage photonic crystal fiber with large-mode-area. J Opt 2019, 21(9), 095701.

A bend-resistant side-leakage photonic crystal fiber with large-mode-area (LMA) is proposed. Simulation results demonstrate that the robust single-mode operation is obtained thanks to an extremely high loss ratio (the minimum loss of high order modes to the loss of fundamental mode (FM)) at the wavelength of 2 μm while the bend radius is as small as 10 cm. Meanwhile, the FM suffers a low bend loss of 0.006 dB m⁻¹ with an effective mode area exceeding 2000 μm² . The bend-resistant performance can be maintained over a broad range of wavelengths from 1.75 to 2.5 μm. Except for a wide waveband, a large tolerance for bend radius is also obtained. The fiber is able to operate under single-mode operation within a range of bend radius from 9 to 24 cm. LMA and single-mode operation under a small bend radius make this fiber have great potential in developing compact high power fiber lasers.

8 illus, 28 ref

006060   DHANOTIA J, BANDE S, BHATIA V, PRAKASH S (Devi Ahilya Univ, Indore- 452 017, Email: sprakash_davv@rediffmail.com) : Histogram error based algorithm for efficient collimation testing. J Opt 2019, 21(9), 095603.

This communication reports an investigation undertaken towards setting collimation of an optical beam using a self-imaging technique and histogram error (HE) based approach. The beam under test illuminates an amplitude-type Ronchi grating. After the grating, a beam splitter is placed such that the grating’s self-images are formed in two perpendicular directions, at the different Talbot planes. The images are then recorded using two identical CCD cameras. Towards implementing a HE based algorithm, first, element-by-element subtraction of the normalized histogram of both self-images is computed. Next, the sum of the elements of the resultant image matrix is determined. Finally, the square of the sum yields the HE. HE provides an estimate of the collimation errors in the beam. For an incident collimated beam, the self-images recorded at different Talbot planes have identical unit magnification with respect to the grating; however, when the beam diverges or converges, the size and fringe width of self-images are differentially magnified or demagnified. Hence, when the beam is collimated, the HE is minimum. For the decollimated beam, the value of HE is higher, and increases as the decollimation errors increase. Using the proposed method, we could set the collimation position to a resolution of 1 μm, which relates to ±0.22 μ radians in terms of collimation angle (for a lens of focal length 300 mm and diameter 40 mm). Experimental results conclusively establish the viability of the technique. Good accuracy and precision in the measurement have been achieved.

8 illus, 2 tables, 40 ref

006071   POLNAU E, VORONTSOV M A, GUDIMETLA R (Dayton Univ, Dayton, United States of America, Email: epolnau1@udayton.edu) : Experimental demonstration of target-in-the loop remote sensing of laser beam and atmospheric turbulence characteristics. J Opt 2019, 21(9), 095602.

A possibility for remote measurement of laser beam and atmospheric turbulence characteristics using the target-in-the-loop atmospheric sensing (TILAS) technique is experimentally demonstrated over a 7 km atmospheric propagation path. The results show that the TILAS approach can be applied for remote sensing of the target-plane intensity scintillations and pathintegrated refractive index structure parameter C_n ² at diverse atmospheric turbulence conditions.

3 illus, 15 ref

006079   ZHANG Q, WANG H, WU P, FU Y, LI X, WANG Q, HAN S (Changchun Univ of Science and Technology, Changchun- 130 022, Email: senhanemail@126.com) : Estimating transmitted wavefronts in a broad bandwidth based on zernike coefficients. J Opt 2019, 21(9), 095601.

Existing technologies and methods for measuring transmitted wavefronts typically operate at only a few specific wavelengths. In this paper, we propose a new method for estimating the wavefront distortion of an optical transmission system in a broad bandwidth. We establish the relationship between the transmitted wavefront and wavelength, using Zernike fringe coefficients to represent the wavefront. From simulations of several different types of optical systems, we found that two formulas can be used to express Zernike-wavelength curves: the Conrady dispersion formula and a new formula that we have named the apochromatic characteristic formula. To reduce the influence of measurement errors on predictions, the fitting method is biased in favor of simulation rather than experimental data. We illustrate the validity of this technique by reconstructing a wavefront transmitted at 671 nm using Zernike polynomials, demonstrating that the predicted wavefront is very similar to the wavefront measured experimentally. Using the Conrady formula, we illustrate that the wavefront of a monochromatic system can be predicted for any wavelength in a broad range, using data from three standard wavelengths. As Seidel coefficients correspond to Zernike coefficients, the relationship between optical aberration and wavelength detailed here can also be applied to areas, such as optical design, optical computing and adaptive optics.

16 illus, 3 tables, 29 ref

006080   ZHOU J, LIN P T (Materials Science & Engineering Dep, Texas A&M Univ, Texas, United States of America, Email: paolin@ece.tamu.edu) : Efficient mid-Infrared vortex beam generation using optical waveguides integrated with micro-spiral phase plates. J Opt 2019, 21(10), 105801.

Vortex beam generation from a mid-infrared photonic chip was numerically demonstrated by engineering the phase front of a waveguide mode. Multi-level micro-spiral phase plates (SPPs) consisting of N segments were patterned on the waveguide facet. The micro-SPP introduced an annular phase change by 2π that converted the Hermite–Gaussian (HG) waveguide mode into Laguerre–Gaussian (LG) mode at topological charge |l| = 1. Using a 3D finite difference time domain simulation, we resolved the near-field optical phase map next to the micro-SPP and its far-field beam profile projected from the waveguide surface. The vortex beam formation was spectrally dependent. A uniform and symmetric donut-shaped pattern corresponding to an ideal vortex beam was created at λ = 3.1–3.3 μm. In addition, the HG → LG mode conversion efficiency was improved by increasing the number of segments, N. Thus, our micro-SPP enabled present photonic circuits to create vortex beams, which is critical for the development of optical interconnection and broadband communication.

5 illus, 35 ref

006063   GHAZIALSHARIF M , FAKHAR B H, ABRISHAMIAN M S (Electrical Engineering Dep, K.N.Toosi Univ of Technology, Tehran, Iran, Email: mghazisharif@email.kntu.ac.ir) : Low power third harmonic generation and all-optical switching by graphene surface plasmons. J Opt 2019, 21(10), 105503.

In this study, we aimed at optimizing the nonlinear properties of the guiding structure of graphene surface plasmon polaritons. The structure is a graphene–metal hybrid waveguide with applicable mode confinement. Focusing electromagnetic power in the graphene sheet improves the harmonic conversion efficiency (0.2 % (−27 dB)) and high self-phase modulation. The third harmonic generation phase-matching condition was satisfied in three-dimensional simulations for longer harmonic generation length. Low loss performance is vital for devices that operate in the terahertz regime (0.3–30 THz), because of the low efficiency offered by the available terahertz pulse generation methods. In this study, low loss propagation was achieved by engineering the chemical potential of graphene. Finally, a frequency-selective all-optical switch was designed by placing a subwavelength resonator in the waveguide. Self-phase modulation enabled optical control of the frequency-selective switch.

13 illus, 70 ref

006076   WANG C, FENG G, LI W, ZHOU S (Sichuan Univ, Chengdu- 610 064, People’s Republic of China, Email: guoing_feng@scu.edu.cn) : Highly coherent supercontinuum generation in CS₂-infiltrated single-core optical fibe. J Opt 2019, 21(10), 105501.

As is generally known, the broadband near-infrared supercontinuum (SC) is significant for applications such as pump-probe spectroscopy, nonlinear spectroscopy, frequency combs and nonlinear optical parametric amplification. We present the first detailed demonstration of approximate near-infrared, octave-spanning SC generation in an all-normal dispersion CS2 single-hole liquid core optical fiber (LCOF). By solving the generalized nonlinear Schrödinger equation, the SC can be calculated at different parameters. The influence of important parameters —including but not limited to the fiber core diameter, pump wavelength, pump power and pulse width—on the supercontinuum generation (SCG) of a CS₂-infiltrated LCOF can be analyzed for the optimization of near-infrared SCG. The results show that at low pump power (such as P₀ = 4 kW), the SC generated by using two pump wavelengths (1.55 μm and 1.95 μm) has spectral flatness, good coherence and is octave-spanning. However, the bandwidth is severely affected by the large pulse duration T₀, and the coherence is seriously influenced by the pulse duration T₀  1200 fs at the pump wavelength of 1.55 μm. The effect of pulse duration on the first-order coherence is greater at short pump wavelengths (1.55 μm) than long wavelengths (1.95 μm). Under high power conditions (such as P₀ = 20 kW), the coherence of the SC generated remains good at the two-pump wavelength. This study explores an optimized scheme for obtaining a broadband SC with high coherence and fine spectral flatness suitable for specific applications.

7 illus, 1 table, 59 ref

006068   LI X, LIANG Y (The 36th Research Institute of China Electronics Technology Group Corp, Jiaxing- 314 033, People’s Republic of China, Email: swindlee@foxmail.com) : Selection of the confining beam for laser direct writing with scanning absorbance modulation. J Opt 2019, 21(10), 105402.

Absorbance-modulation optical lithography has been proposed to obtain super-resolution grating patterns with far-field optics. However, the patterns are monotonous since the interference fringes are used as the confining beam. We propose laser direct writing with scanning absorbance modulation to produce free super-resolution patterns. Four kinds of optical vortex beams are studied as the confining beam and the performance of scanning absorbance modulation using each of them is simulated. In conclusion, the selection of the best confining beam has to follow three criteria and an example is the 2-level, 1.5-order optical vortex beam.

17 illus, 3 tables, 36 ref

006074   REN P, JIA Y, JIA W, FAN C (Zhengzhou Univ, Zhengzhou- 450 001, People’s Republic of China, Email: lchunzhen@zzu.edu.cn) : Plasmon-induced transparency in graphene with double asymmetric L strips. J Opt 2019, 21(10), 105101.

In this work, plasmon-induced transparency has been realized with graphene metamaterial consisting of double asymmetric L strips. Due to the weak hybridization between this two L strip resonator, a clear transparency window on the transmission spectrum of the originally opaque frequency range can be realized. With a Lorentz coupled oscillator model, our theoretical results of the transmission spectra agree well with the numerical calculations. Moreover, the transparency window can be dynamically modulated via regulating the Fermi energy and carrier mobility. The reflection and absorption spectrum has also been analyzed concretely, and its absorption rate approaches as high as 50 %, which provides a solid application in terahertz absorbers. According to the effective medium theory, the sensitivity of the transparency window as a function of the surrounding medium embodies a linear relationship. As for its dispersion behavior, the group index of the structure can reach up to 1125. This work shadows a fascinating application in the area of highly integrated sensor devices, filters or absorbers.

10 illus, 40 ref

006064   KANG B, MOTOKURA K, FUJII M, NESTERENKO D V, SEKKAT (Electrical and Electronic Engineering Dep, Kobe Univ, Kobe 657-8501, Email: s.hayashi@dragon.kobe-u.ac.jp) : Fano resonant behaviour of waveguide mode in all-dielectric multilayer structure directly monitored by fluorescence of embedded dye molecules. J Opt 2019, 21(10), 105006.

A method that allows direct monitoring of Fano resonant behaviours of local electric fields inside a waveguide layer in multilayer structures was developed. All-dielectric multilayer structures consisting of two polystyrene waveguide layers separated by a polyvinyl alcohol spacer layer were prepared. One of the waveguide layers was doped with fluorescent dye molecules. The fluorescence spectra of the sample were measured in a Kretschmann attenuated-total-reflection geometry as a function of the angle of incidence of the excitation light. The angle-scan fluorescence excitation spectra exhibited a sharp Fano line shape superposed on a broad band. Results of electromagnetic calculations of the electric field distribution inside the multilayer structure revealed that the local electric fields inside the dye-doped waveguide layer exhibit Fano resonant behaviours due to the near-field coupling to the waveguide mode supported by another waveguide layer. Using the calculated local electric fields, theoretical fluorescence spectra were calculated based on a point dipole model. The theoretical fluorescence spectra were found to reproduce the experimental ones very well, confirming that the observed Fano line shapes in the fluorescence spectra are the manifestation of the Fano resonant behaviours of the local electric fields inside the dye-doped layer.

4 illus, 2 tables, 60 ref

006081   ZHOU X, GUO X, SHKURINOV A, ZHU Y (Shanghai for Science and Technology Univ, Shanghai- 200 093, Email: xgguo_sh@qq.com) : Concentric-ring-grating-induced strong terahertz near-field enhancement on a micro-tip. J Opt 2019, 21(10), 105005.

A terahertz near-field source, composed of a subwavelength metallic concentric ring grating on a dielectric slab with a micro-tip, is proposed. The field enhancement property and the field distribution near the tip apex are studied theoretically. A volume-averaged energy density enhancement factor of 550 around the tip apex region could be obtained for radial polarized field illumination. Compared with conventional scanning near-field optical microscopies (SNOMs), about 15-fold enhancement of near-field energy density is obtained by using the proposed near-field source. We attribute such a strong enhancement to the guided resonant modes launched by the radial grating, the axial symmetry of the device, and the radial polarization of incident beam. The resonance frequencies of the device are controlled by varying the grating period and the thickness of dielectric substrate. The proposed device is useful for improving the coupling efficiency of SNOMs.

5 illus, 43 ref

006082   ZHUANG H, XU H, KONG F, WANG Y, GAO M, LI K (Shandong Jianzhu Univ, Jinan- 250 101, Email: zhuanghuawei@sdjzu.edu.cn) : Phase-coupled plasmon-induced transparency and slow light in graphene stub detuning structures. J Opt 2019, 21(10), 105004.

Tunable phase-coupled plasmon-induced transparency (PIT) and slow light are investigated theoretically and numerically by cascading two stub resonators with a certain distance along the graphene bus waveguide. The theoretical model is analyzed by the coupled mode theory and transfer matrix method. The transmission and slow light effects in the transparent window can be tailored not only by changing the detuning of the two stub resonators but also by adjusting the separation distance L or chemical potential between the two stubs. In addition, multiple PITs and slow light are proposed and simulated with a triple-stub structure. By the numerical simulation, a conclusion is drawn that the added phase coupling can trap the SPPs in the waveguide with longer time, resulting in the slow wave effect more obviously than that with only the detuning coupled method. The proposed slow light structure will pave another way towards dynamic controlling slow light in the terahertz and mid-infrared regimes

6 illus, 41 ref

006067   LI C, ZOU J, ZHANG J, XU W, GUO C, LIU K, YUAN X, QIN S, ZHU Z (National Univ of Defense Technology, Changsha- 410 073, Email: zzhwcx@163.com) : Hybrid magnetic plasmon resonance induced tunable half-wave plate based on graphene-dielectric-metal structure. J Opt 2019, 21(10), 105003.

We propose a terahertz half-wave plate composed of a periodic array of rectangular-shaped metal-dielectric-graphene (RMDG) sandwich structure on a dielectric substrate supported by a thick metallic film. The role of graphene sheet is to combine with the rectangular-shaped metal to provide tunable anisotropic hybrid magnetic plasmon resonance. The results reveal that about 90 % of energy of the incident linearly polarized light at a certain frequency is converted to the perpendicular polarization direction after reflection from the wave plate. The high energy polarization conversion efficiency is attributable to the fact that the electric vector of the hybrid magnetic plasmon resonance in RMDG is mainly perpendicular to the graphene sheet and the absorption loss of graphene is suppressed. The half-wave plate we demonstrate here, consisting of nanostructured metal and non-structured graphene, utilizes mature metal nanostructure preparation process and avoids the graphene processing, which consequently facilitates the fabrication and promotes the application of half-wave plate.

12 illus, 1 table, 49 ref

006059   CHATRASINGH M, SUTHAKORN J (Biomedical Engineering Dep, Mahidol Univ, Salaya, Thailand, Email: jackrit.sut@mahidol.ac.th) : A novel design of N-Fiducial phantom for automatic ultrasound calibration. J Med Phys 2019, 44(3), 191-200.

Freehand ultrasound (US) is a technique used to acquire three-dimensional (3D) US images using a tracked 2D US probe. Calibrating the probe with a proper calibration phantom improves the precision of the technique and allows several applications in computerassisted surgery. N-fiducial phantom is widely used due to the robustness of precise fabrication and convenience of use. In principle, the design supports single-frame calibration by providing at least three noncollinear points in 3D space at once. Due to this requirement, most designs contain multiple N-fiducials in unpatterned and noncollinear arrangements. The unpatterned multiple N-fiducials appearing as scattered dots in the US image are difficult to extract, and the extracted data are usually contaminated with noise. In practice, the extraction mostly relied on manual interventions, and calibration with N-fiducial phantom has not yet achieved high accuracy with single or few frame calibrations due to noise contamination. In this article, we propose a novel design of the N-fiducial US calibration phantom to enable automatic feature extraction with comparable accuracy to multiple frame calibration. Along with the design, the Random Sample Consensus (RANSAC) algorithm was used for feature extraction with both 2D and 3D models estimation. The RANSAC feature extraction algorithm was equipped with a closed-form calibration method to achieve automatic calibration. The accuracy, precision, and shape reconstruction errors of the calibration acquired from the experiment were significantly matched with the previous literature reports. The results showed that our proposed method has a high efficiency to perform automatic feature extraction compared to conventional extraction performed by humans. 

9 illus, 2 tables, 31 ref

006069   MALIKA M, SONAWANE S S (Chemical Engineering Dep, Visvesvaraya National Institute Of Technology, Maharashtra- 440 010) : Review on application of nanofluid/nano particle as water disinfectant. J Indian Assoc Environ Manag 2019, 39 (1-4), 21-4.

Nanoparticles like CNT, MgO, silver, Zno, CuO and self-cleaning TiO₂  at certain loading showed better activity on reduction in growth of microorganisms. To overcome the undesired properties of nanoparticles they are doped together to form a composite or hybrid to attain the better performance over the various range of bacteria. The nanoparticles were synthesized eco-friendly from natural resources to attain the biodiversity. The antibacterial activity was further measured in terms of COD, MIC, MBC, optical density and UV absorption. The review focused broadly on the single/hybrid/composite nanoparticle based nanofluid for treating wastewater using renewable -solar energy source without any by product recycling problems.

1 table, 30 ref

003417   SINGH S, PRADHAN A, BISWAL M P (Indrashil Univ, Mehsana 382740, Email: avik02iitkgp@gmail.com) : Multi-objective solid transportation problem under stochastic environment. Sadhana 2019, 44(5), 105.

In real life, three-dimensional (solid) transportation problem is an uncertain multi-objective decision-making (MODM) problem. In particular, it involves searching for the best transportation set-up that meets the decision maker’s preferences by considering the conflicting objectives/criteria such as transportation cost, transportation time, environmental and social issues. To tackle such complex situations, this paper proposes a general formulation of the multi-objective solid transportation problem (STP) with some random parameters. The paper makes the following contributions: (i) proposes a solution methodology based on chance-constraint programming technique to solve an STP with the uncertainty characterized by gamma distribution, (ii) proposes the initial feasibility conditions for the problem and (iii) extends fuzzy programming approach for solving the multi-objective stochastic problems. A numerical example is presented to illustrate the model and methodology.

4 illus, 33 ref

003397   NONGMEIKAPAM K, KUMAR W K, MEETEI O N, TUITHUNG T (Electronics and Communication Engineering Dep, North Eastern Regional Institute of Science and Technology, Nirjuli, Arunachal Pradesh, Email: wahengbam.kanankumar@gmail.com) : Increasing the effectiveness of handwritten Manipuri Meetei-Mayek character recognition using multiple-HOG-feature descriptors. Sadhana 2019, 44(5), 104.

Detection and reading of the text from natural images is a difficult computer vision task, which is essential in a variety of emerging applications. Document character recognition is one such problem, which has been widely studied and documented by many machine learning and computer vision researchers, which is practically used for solving applications like recognizing handwritten digits. In this paper, a new approach for efficiently extracting cognition out of a total of 56 different classes of Handwritten Manipuri Meetei-Mayek (HMMM) (an Indian language) is described. Although character recognition algorithms have been researched and developed for other Indian scripts, no research work has been reported so far for recognizing all the characters of the Manipuri Meetei-Mayek (MMM). The work begins with a thorough analysis of the recognition task using a single hidden layer type Multilayer Perceptron Feedforward Artificial Neural Network with Histogram of Oriented Gradient (HOG) feature descriptors. After reviewing the level of accuracy and time it takes to train the network, the limitations are experimentally removed using multiple-sized cell grids using HOG descriptors. HOG, being a gradient-based descriptor, is very efficient in data discrimination and very stable with illumination variation. For efficient classification of the HOG features of the MMM, a linear multiclass support vector machine (SVM) classifier has been proposed for classifying the different offline characters because of its simplicity and speed. The classification based on linear multiclass SVM yielded a very high overall accuracy of 96.928 %.

8 illus, 7 tables, 22 ref

006062   GAIKWAD C J, SIRCAR P (Electrical Engineering Dep, Indian Institute of Technology Kanpur, Kanpur- 208 016) : On determination of tonic note for singers of Indian music. IETE Tech Rev 2019, 36(5), 535-46.

This paper addresses the problem of tonic note selection and voice range determination for singers of Indian music. The tonic note of a singer determines the pitches of other notes used in raga/song sung by the singer. The voice range of a singer refers to the span of notes over which the singer’s voice is powerful and melodious. In Indian music, the main emphasis is on the vocals, and instruments are played as an accompaniment. We study different perceptual attributes of the singer’s voice and develop criterion that is considered in the selection of tonic note. We analyze voices of famous Indian singers and illustrate the criterion considered for the selection of tonic note. According to the developed criterion different parameters are calculated and analyzed for all the notes of the singer. These parameters are then used to select the tonic note and voice range of the singers.

7 illus, 15 tables, 29 ref

006070   PATTAPU U, DAS S (Electronics Engineering Dep, Indian Institute of Technology, Dhanbad- 826 004) : A spurious-free 5.8 GHz circular patch antenna for rectenna applications. IETE Tech Rev 2019, 36(5), 510-6.

In this paper, a 5.8 GHz capacitive coupled circular patch antenna having harmonic suppression capability has been designed and fabricated for wireless power transfer applications. Harmonics suppression has been achieved up to the fourth order of the fundamental operating frequency by using two stubs and one split circular slot. Such a type of simple geometry for harmonic suppression is definitely a potential advantage as compared to the earlier published similar type of work where complex geometry has been involved for harmonic suppression. Surface current distributions on the antenna have been shown at harmonic frequencies to illustrate the harmonic suppression graphically. Model equivalent circuit of the presented antenna also has been shown to explain the harmonic suppression functionality in detail. Proposed antenna has been fabricated and the simulation results are experimentally verified.

16 illus, 1 table, 19 ref

006066   KUMAR P, DWARI S, SINGH S, KUMAR J, KUMAR A (Electronics Engineering Dep, Indian Institute of Technology, Dhanbad, Jharkhand) : Conductor backed CPW-fed dual-mode excited high gain cylindrical cavity DRA for unmanned aircraft systems (UAS) or drone data-link applications at C band. IETE Tech Rev 2019, 36(5), 463-74.

In this article, a dual-mode high gain cylindrical cavity dielectric resonator antenna (CCDRA) excited by conductor backed coplanar waveguide (CB-CPW) has been investigated for unmanned aircraft systems (UAS) or drone data-link applications at the C band. A CB-CPW has been used to excite the CCDRA to achieve bore-sight radiation pattern. A wide impedance bandwidth of 1100 MHz (4.3–5.4 GHz) has been achieved due to excitation of HE_11δ and HE_21δ modes in dielectric resonator antenna (DRA) by inserting a cylindrical shaped air cavity in DRA. The antenna is finally optimized using 3-D electromagnetic simulator to achieve high gain, good impedance bandwidth, and stable radiation pattern. The prototype antenna achieves 22 % impedance bandwidth with more than 7.5 dB average peak gain and 95 % estimated efficiency throughout the operating band. The experimental results validate the performance of CCDRA. Such antenna can be easily installed on the unmanned aerial vehicle/drone platform for data-link as well as other applications.

12 illus, 6 tables, 27 ref

006073   PRAJAPATI A K, PRASAD R (Electrical Engineering Dep, Indian Institute of Technology, Roorkee, Uttarakhand) : Reduced order modelling of linear time invariant systems using the factor division method to allow retention of dominant modes. IETE Tech Rev 2019, 36(5), 449-62.

This paper proposes a new model order reduction method for the large-scale dynamic systems using the factor division approach to allow the preservation of dominant poles. For a given higher order model, the denominator of the lower order system is obtained by preserving the dominant poles of the original model, while the numerator is calculated by using the factor division algorithm. The proposed technique guarantees the preservation of stability, steady-state value, and initial few time moments of the original model in the reduced system. The simplicity, accuracy, and validation of the proposed technique are shown by the three standard examples taken from the literature.

5 illus, 3 tables, 88 ref

006072   PRAJAPATI A K, PRASAD R (Electrical Engineering Dep, Indian Institute of Technology, Roorkee, Uttarakhand) : Order reduction of linear dynamic systems by improved routh approximation method. IETE J Res 2019, 65(5), 702-15.

In this paper, a new simplified Routh approximation technique is proposed for the model order reduction (MOR) of large scale linear time-invariant systems. In reduced order modeling, the Routh approximation technique described in the literature is based on the alpha and beta parameters. This paper presents a new simplified Routh approximation technique for the MOR involving only alpha parameters to make the proposed technique simple. In this technique, the denominator polynomial of the lower order system is obtained by the Routh approximation technique and the numerator polynomial is computed by a simple mathematical algorithm as discussed in the proposed scenario. The additional advantage of the proposed method is that it always gives a stable reduced model if the original higher-order system is stable. To illustrate the proposed method, the fourth-order DC–DC converter model is reduced to its second-order reduced model. The modeling of DC–DC converter in continuous conduction mode is also developed and whose final output is a complete linear circuit model. In order to check the effectiveness and accuracy competitive to other popular and recent techniques in the literature, the proposed method has been applied on various standard numerical examples.

6 illus, 5 tables, 83 ref

006058   BANERJEE A, BISWAS B (Applied Electronics and Instrumentation Engineering Dep, Maulana Abul Kalam Azad Univ of Technology, Adisaptagram, Hooghly) : Influence of time delay on pull-in behaviour of dither optical phase-lock loop. IETE J Res 2019, 65(5), 679-88.

This paper analyses the impact of loop propagation delay on the pull-in behaviour of dither optical phase-lock loop (OPLL), neglecting the shot noise and phase noise of the loop. Analytical expressions of pull-in voltage, pull-in range, and acquisition time are presented in terms of all the parameters affecting the loop acquisition. Also, the influence of dither signal on the pull-in performance of dither OPLL is studied in the presence of loop propagation delay. It is found that the time delay associated with the filtering process within the loop gives rise to degradation in acquisition capability. In addition, dither signal allows pull-in from much larger frequency offset, decreases the acquisition time of the loop, and improves the acquisition characteristics of dither OPLL in terms of the pull-in voltage in the presence of loop delay. The tracking performance of dither OPLL regarding phase error variance is investigated considering laser phase noise, photo-detector shot noise, and loop propagation delay. Simulation results are given in support of the analytical results.

9 illus, 18 ref

006077   WULANDARI P P, ADIWIBOWO M T, REDJEKI A S, IBADURROHMAN M, SLAMET (Chemical Engineering Dep, Indonesia Univ, Depok, Indonesia, Email: slamet@che.ui.ac.id) : Synthesis of eco-friendly detergent based on crude palm oil and titania nanoparticles. Asian J Chem 2019, 31(10), 2394-6.

In this work, we report the synthesis of eco-friendly detergent from crude palm oil and titania. Crude palm oil was converted into methyl ester sulfonate through esterification, transesterification and followed by sulfonation process. As-produced methyl ester sulfonate was characterized with Fourier transformed infrared spectroscopy (FTIR), gas chromatography-mass spectroscopy (GC-MS), liquid chromatography mass spectroscopy (LCMS) and surface tension analysis. Detergents were synthesized by dispersing titania nanoparticles into methyl ester sulfonate solution, forming a nanofluid. Stability and detergency of the nanofluidic detergents were then evaluated. The results showed that the nanofluid detergents were stable in the presence of 0.1 wt % titania and the photocatalytic activity of titania nanoparticles improved the ability of nanofluidic detergents to remove dirt as well as degrading the surfactant residues in the laundry waste stream.

4 illus, 13 ref

004738   RAMACHANDRAN J, RAVIKUMAR V, LALITHA R (Soil and Water Conservation Engineering Dep, Tamil Nadu Agricultural Univ, Trichy- 621 712, Email: eeesurya.tnau@gmail.com) : Assessment of drip lateral design methods based on uniformity coefficient. Indian J Agric Res 2019, 53(4), 496-9.

In this paper, six drip lateral design methods were selected and a comparative assessment was done to find its practical applicability for finding accurate uniformity coefficient. Step-By-Step (SBS) method, Differential method (DM), Constant Discharge method (CDM), Variable discharge method (VDM), Outlet variation method (OVM) and Statistical method (STM) were the different methods assessed. The percentage relative error in calculating the uniformity coefficient by different methods were obtained as the difference between step-by-step method (true) value and alternate method (observed) value. These errors were tabulated. VDM and OVM method performed well with equal accuracy to SBS method at different slopes. For L=250 m, DM method performed well. The STM performed good for down slope and lateral length of 250 m with 6 percent relative error. The method having lesser relative percentage error can be selected by the design engineers for designing the laterals from the relative percentage error tables.

15 ref

004737   RAJESH S (Mechanical Engineering Dep, Raghu Engineering Coll, Visakapatnam-531 162, Email: rajeshsinguru@gmail.com) : Rain sensor capsule (RSC) for farmers during un-seasonal rains in post-harvesting period. Indian J Agric Res 2019, 53(4), 483-7.

Farmers are backbone of India and they suffer many hurdles while growing crops. In post-harvesting steps, drying crops plays a major role in grain production. About 70 % of the threshed grains are sun-dried in many regions. During sudden rains farmers face difficulty to cover the threshed grains and some of them die because of thunderstorm/lighting with this older methods. It necessitates to design a new system for these conditions instead of older methods. The aim of the project is to provide an innovative design for helping farmers from unseasonal rains easily. The newly modelled Rain Sensor Capsule for farmers, whose operation is compiled by the automatic rain sensor, wooden capsule, controllers and power conversion unit. The capsule is modelled in AutoCAD software package, then a prototype is fabricated and tested. 

17 ref

004713   BISWAL P, DAHIYA Y S (Human Engineering Dep, Institute of Aerospace Medicine, Bangalore, Karnataka, Email: drpunyashlok@gmail.com) : Principal component analysis: The path ahead for aircrew-aircraft compatibility at the Institute of Aerospace Medicine. Indian J Aerospace Med 2019, 63(1), 8-15.

The Institute of Aerospace Medicine provides design consultancy on aircraft-aircrew compatibility on a number of fixed-wing as well as rotary-wing aircrafts during various stages of development. Till date, the cockpit compatibility of aircrew has been determined based on the percentile concept. Percentiles, though useful when dealing with a single parameter, pose major design and fitment problems when considering multiple parameters simultaneously as in aircraft cockpit design. The concept of multivariate analysis has been the solution which the aviation industry the world over has accepted in overcoming this problem. This paper presents the Institute of Aerospace Medicine initial foray into the field of multivariate analysis, specifically principal component analysis (PCA) to achieve desired aircrew fitment in the aircraft cockpit right from the design stage. The fighter aircraft of the near future is being designed using the anthropometric parameters available in the IAF aircrew anthropometry survey 2013. Of the 57 parameters available, six parameters critical to the design of the cockpit were subject to PCA to derive three principal components. About 96 % confidence ellipse was drawn on the plot of the principal components. From this, along the different axes, 21 boundary individuals were identified defining the extreme individuals in various combinations of the six parameters. The use of more than 2 parameters is not amenable to sequential use of percentiles. As the number of parameters considered increases, it leads to reduced fitment percentage. The use of PCA allows consideration of critical parameters together at one go. The design aim is changed from the 3rd to 97th percentile to an overall aim of fitting 96 % of the target population in the cockpit. The boundary individual’s entire anthropometry data are used to create boundary manikins for use in computer-aided design models. The fitment of these boundary individuals ensures that if these individuals fit, all others would fit in the cockpit. This concept brings about a paradigm shift in the aircrew-aircraft compatibility in the aviation industry in India.

8 illus, 3 tables, 11 ref

004718   HU D, ZHANG K, LI F (Wuhan Univ of Technology, Wuhan- 430 063, Email: hudan1989.happy@163.com) : Dynamic behavior of saturated poroelastic continuum by simplified formulation of Biot’s theory. Indian Geotech J 2019, 49(4), 455-66.

The behavior of saturated, porous media under dynamic or quasi-static loads was firstly formulated by Biot. Based on Biot’s theory, various possible simplifications have been proposed such as neglecting the second time derivative of the relative displacement. In addition, an even more simplified version has been proposed where the inertial terms in the generalized Darcy’s law are neglected as well. This paper aims to explore the advantages and limitations of that simplified formulation with the help of a linear one-dimensional (1D) poroelastic column subjected to periodic dynamic loading. Two non-dimensional parameters which are related to the permeability, excitation frequency, and material properties are introduced, and the analytical solutions are obtained and depicted graphically in cases of varied permeability and frequencies. Subsequently, a schematic diagram is developed to serve as guideline to determine whether the simplification is tenable, or the only meaningful solution is available by complete Biot’s theory.

9 illus, 3 tables, 23 ref

004747   SINGH A, RAO K S, AYOTHIRAMAN R (Civil Engineering Dep, Indian Institute of Technology Delhi, New Delhi- 110 016, Email: araman@civil.iitd.ac.in) : A closed-form analytical solution for circular opening in rocks using Drucker–Prager criterion. Indian Geotech J 2019, 49(4), 437-54.

Wellbore and tunnel problems are of true triaxial stress state, even if the ground is under axisymmetric loading condition. A closed-form analytical solution is proposed using Drucker–Prager failure criterion. The solutions are obtained for rock mass exhibiting elastic– perfectly plastic or elastic–brittle–plastic behaviour. The proposed solution is then compared with the finite element analysis (FE-analysis) results. Parametric studies are also carried out. The results of the proposed analytical solution are found to be in good agreement with the FE-analysis results. The proposed analytical solution can thus be used for predicting the stresses and deformation of underground circular openings considering true triaxial stress state.

14 illus, 8 tables, 56 ref

004719   HUANG F, WANG Y, WEN Y, LIN Z, ZHU H (Chongqing Jiaotong Univ, Chongqing- 400 074, Email: huangfeng216@126.com) : The deformation and failure analysis of rock mass around tunnel by coupling finite difference method and discrete element method. Indian Geotech J 2019, 49(4), 421-36.

The deformation and failure mechanics of the rock mass around tunnel after excavation are very important for design and construction. Simulation is always difficult when using either the finite difference method (FDM) or discrete element method (DEM). Consequently, a two-dimensional (2D) coupling analysis method was introduced by employing the commercial codes FLAC for FDM and PFC for DEM simultaneously. The developed 2D coupled method was applied to analyze the mechanical response of Tongluoshan tunnel which is the longest interval railway tunnel in China. By comparison with theoretical method, the displacement by numerical simulation shows good agreements with analytical equation for cases with different ground stress ratios. The reasonable dimension for DEM model should be 4 times of tunnel radius to assure reliable results in terms of efficiency and accuracy of calculation. Generally, the maximum of vertical displacement will increase according to the increase in stress ratio. Fracture of rock mass initiates and visible collapse of tunnel happens when ground stress is over 4 MPa (54 % of uniaxial compressive strength) and 6 MPa (81 % of uniaxial compressive strength), respectively. Both fracture and collapse predominantly concentrate above tunnel crown.

24 illus, 4 tables, 21 ref

004749   SINGH R, DAS A, SATHIYAMOORTHY R (Civil Engineering Dep, Indian Institute of Technology Kanpur, Uttar Pradesh- 208 016, Email: arghya@iitk.ac.in) : Efficacy of coupled solid–fluid formulation in regularizing an ill-posed finite element model. Indian Geotech J 2019, 49(4), 409-20.

Analyzing instability in geomaterials in the form of shear localization using finite element discretization leads to erroneous results if the constitutive formulation does not contain any internal length scale. Thus, the solution becomes mesh dependent. The remedy of such problem is commonly known as regularization. Use of coupled solid–fluid formulation for the modeling of saturated porous media is one the remedial measures or regularizations schemes. The present study explores the efficacy of this regularization scheme by modeling the deformation in stone columns. Stone column is a ground improvement technique to accelerate consolidation settlement in low permeable soils. During consolidation, stone column also undergoes axial deformation along with the surrounding soil. The deformation mode in stone column is either punching or bulging or shear failure depending on the rate of loading and boundary conditions. Earlier studies indicate shear deformation in stone column is often associated with complex localized bands, which cannot be captured through the conventional analytical solutions. The present analysis using finite elements demonstrates that with mesh refinement the thickness of shear band within the stone column reduces despite using such coupled formulation. However, the overall time settlement profile of the column is unaffected by localization. In addition, the results are found to be affected by the selected time increment as the total consolidation time varies with the step time variation. The regularization scheme seems partially successful to model the localized deformation in stone columns.

9 illus, 3 tables, 41 ref

004746   SHIRASB A, KARIMI A H, HAMIDI A, AHMADI M M (Civil Engineering Dep, Kharazmi Univ, Tehran, Iran, Email: hamidi@khu.ac.ir) : A critical state constitutive model for the isotropic thermal compression of structured sand–bentonite buffers. Indian Geotech J 2019, 49(4), 398-408.

The sand–bentonite mixture is used as the buffer layer in nuclear waste disposals. The buffer layer, as a non-permeable protective layer, is generally exposed to temperature gradients and the long-term subjection to temperature results in creep and more intact structure for the layer. In the present study, thermally induced structure and its effects on the isotropic compression behavior and volume change behavior of buffer layer are evaluated. Thermal consolidation tests were conducted using a modified triaxial cell capable of handling temperatures up to 90 °C. In order to investigate the effects of thermal gradients on the behavior of the mixture, saturated specimens were cured at constant temperatures of 40 °C, 60 °C and 80 °C, for time periods of 1, 3 and 5 days. Then, the consolidation tests were performed holding the curing temperature at a constant value up to end of the test. The results show that when the soil experiences higher temperatures for longer curing periods, the behavior of reconstituted soil is shifted from the reconstituted to a structured one which is an effect of induced creep in high-plasticity bentonite portion. Using the results of the tests performed in this study, a critical state-based constitutive model is proposed to simulate thermally induced volume change behavior of structured mixture. The capability of the proposed model is verified based on the experimental results and it is proved that the proposed model predictions are in good agreement with the experimental data.

13 illus, 5 tables, 39 ref

004716   FUENTES W, LASCARRO C (Civil and Environmental Engineering Dep, Del Norte Univ, Barranquilla, Colombia, Email: fuentesw@uninorte.edu.co) : Extension of a constitutive model for sands to account for the sample preparation method. Indian Geotech J 2019, 49(4), 381-97.

In this article, an existing constitutive model for sands is extended to account for the fabric effect arising from the sample preparation method. The ISA constitutive model, proposed by Fuentes and Triantafyllidis (Int J Geomech 39:1235–1254, 2015), serves as reference model to be extended. The proposed extension modifies the formulation of the characteristic void ratios, namely the maximum and critical void ratios. It features the conservation of a unique critical state line under large deviator strain amplitudes in order to be consistent with other works. The model performance is evaluated with some element test simulations of samples with different preparation methods. It also includes the simulation of a scaled foundation test on a sand deposited by aerial discharge. The simulations showed that many effects related with the material fabric are captured with the proposed formulation.

16 illus, 3 tables, 47 ref

004709   BAJPAI S, BAJPAI V, DEY A, GHOSH S, JHA M K (Chemical Engineering Dep, National Institute of Technology, Jalandhar- 144 011, Email: bajpais@nitj.ac.in) : Study of adherence kinetics of Escherichia coli on cotton knitted fabrics. Indian Chem Eng 2019, 61(3), 296-308.

Textile materials especially those used in hospitals, food industry, sportswear, infant wears, bath rooms, home and kitchen are susceptible to the attacks of various harmful microorganisms present in the environment. The study of bacterial adherence on such microbial infested fabrics is a pre-requisite to develop suitable antimicrobial finished articles. This work therefore aimed towards studying bacterial adherence of Escherichia coli on 100 % cotton knitted fabrics. Lowry’s method was used to quantify the adherent bacterial cells to the fabric. The adherence was studied and compared for three differently pretreated fabrics. The effect of agitation time and pH on adherence was also investigated. The kinetic data were analysed by first-order kinetics using Lagergren equation. The Gibb’s free energy for the adherence process was found to be −3.753 kJ mol⁻¹ . The mechanism of adherence was understood with the help of Scanning Electron Microscope (SEM) and Fourier transform infra-red (FTIR) spectroscopy. SEM micrograph suggests that adherent bacteria did not uniformly cover the entire surface of the cotton fabric. They were found more near the creases present on cotton indicating that surface morphology plays significant role in bacterial adherence. Comparing FTIR spectra of E. coli and cotton fabric suggests that hydrophilicity promotes the bacterial adherence.

10 illus, 2 tables, 37 ref

004703   ADENIYI A G, OGUNLEYE O O, DUROWOJU M O, ODEYEMI S O (Chemical Engineering Dep, Ilorin Univ, Ilorin, Nigeria, Email: adeniyi.ag@unilorin.edu.ng) : Modelling stochastic response of type 304 stainless steel (SS-304) crevice corrosion in chloride environments. Indian Chem Eng 2019, 61(3), 286-95.

The stochastic corrosion response of creviced SS-304 in chloride environment was studied. The crevice assembly used for this study comprised coupon (SS-304), polytetrafluoroethylene (crevice former) and fasteners (titanium bolt, nut and washers) designed in three configurations with crevice scaling factor of 8, 16 and 24, respectively. An immersion test was carried out on each configuration having 40 crevice sites and immersed in various chloride solution concentrations of 1.5, 3.0 and 4.5 w/w % simulating environmental conditions A, B and C, respectively, for 60 days to study the stochastic nature of the initiation and propagation of cc in chloride environments according to ASTM G78. Data obtained were used to develop a Monte Carlo’s model of the crevice corrosion pattern which confirmed the stochastic nature of the crevice corrosion. The probability of attack of SS-304 within 30 days was 0.150, 0.300 and 0.425 for A, B and C, respectively, while the extreme value of the propagated depth of attack was predicted from the stochastic models developed. The developed model is a useful tool for predicting the maximum depth of attack possible under uncertain crevice corrosion of SS-304 in chloride environment.

8 illus, 7 tables, 16 ref

004731   PADHI R K, DORA D T K, MOHANTY Y K, ROY G K, SARANGI B (Petroleum Engineering Dep, KL Univ, Guntur, Email: tapasdora@gmail.com) : Effect of tapered angle on hydrodynamics of homogenous ternary mixture of regular particles in a three-phase tapered fluidized bed. Indian Chem Eng 2019, 61(3), 269-85.

Hydrodynamics characteristics, namely bed pressure drop, bed fluctuation and expansion ratios have been studied for regular particles in a threephase tapered fluidised bed. For this, experiments have been carried out in different tapered columns with glass beads as solid phase, compressed air as gas phase and water as the liquid phase. The effect of tapered angle, initial static bed height, average particle size and superficial gas velocity on the hydrodynamic characteristics has been studied. Correlations have been developed for the three hydrodynamic characteristics using both dimensional and statistical analysis. Experimental values of bed expansion and fluctuation ratios have been found to agree well with those calculated from developed correlations.

10 illus, 11 tables, 26 ref

004754   TIWARI S, SAWANT P, RAHMAN I (Chemical Engineering & Process Development Div, National Chemical Laboratory, Maharashtra- 411 008, Email: r.imran@ncl.res.in) : Recursive orthogonal least squares based adaptive control of a polymerisation reactor. Indian Chem Eng 2019, 61(3), 236-47.

A Nonlinear Internal Model Control (NIMC) scheme, based on a recursively updated Radial Basis Function Network (RBFN), is applied to control the nonlinear Polymerisation process. Recursive Orthogonal Least Squares (ROLS) algorithm recursively updates the weighting matrix of RBFN in real time, such that modelling errors are minimised. In addition to the ROLS based adaptive IMC, a non-adaptive IMC, based on the fixed Orthogonal Least Squares (OLS) algorithm and a normal PID controller are also applied to control the polymerisation process. The simulated results show the effectiveness of the ROLS based controller in terms of response time to step changes and disturbance rejection capabilities over the classical PID controller and the fixed OLS based IMC. Also, the proposed algorithm fits well in the IMC framework.

8 illus, 2 tables, 19 ref

004744   SHADULLA S, RAJ K S, NAIDU S V (Chemical Engineering Dep, Andhra Univ, Visakhapatnam, Andhra Pradesh, Email: profnaidu90@gmail.com) : Synthesis, characterisation and performance analysis of multiwalled carbon nanotubes supported platinum catalyst for proton exchange membrane fuel cells. Indian Chem Eng 2019, 61(3), 221-35.

Multi-walled carbon nanotubes (MWCNTs) supported Platinum catalyst (20 wt %) was synthesised using a standard procedure. The nanocatalyst was characterised using physical methods such as scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX), X-ray powder diffraction (XRD) as well as electrochemical methods such as electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and linear sweep voltammetry (LSV). Membrane electrode assemblies (MEAs) were fabricated for a proton exchange membrane fuel cell (PEMFC) of 25 cm² active area using variable loadings of nanocatalyst on anode and cathode. Experimental analysis was conducted to investigate the effect of nanocatalyst loading under the influence of variable operating parameters such as cell temperature, gas humidification temperatures on the output performance of the PEMFC. Comparative polarisation curves were drawn to show the impact of nanocatalyst loading on cell performance under similar operating conditions. Output comparisons were made with standard literature data to analyse MEA performance.

11 illus, 2 tables, 20 ref

004707   AYDIN F, SUN Y, TURAN M E (Metallurgy and Material Engineering Dep, Karabuk Univ, Karabuk, Turkey, Email: fatih.aydin@karabuk.edu.tr) : Investigation of microstructure, mechanical and wear behaviour of B₄C particulate reinforced AZ91 matrix composites by powder metallurgy. Indian J Chem Technol 2019, 26(4), 351-4.

In this study, AZ91 and AZ91 matrix composites reinforced with three weight fractions (10, 20 and 30 wt. %) of B₄C particulates have been produced by powder metallurgy using hot pressing. Microstructure, hardness, density and mechanical properties of the samples are investigated. Microstructure characterization revealed the uniform distribution of particulatesin matrix. The presence of Mg, Mg₁₇Al₁₂ and B₄C are verified by SEM and XRD. Wear tests are performed under loads of 5, 10, 20 and 30 N. Wear tests show that wear performance of the composites is improved with increasing particulate content. Observed wear mechanisms are oxidative and abrasive. The addition of B₄C particulates led to significant increase in hardness, 0.2% compressive yield strength, ultimate compressive strength and failure strain.

7 illus, 2 tables, 11 ref