654 research outputs found
Sort by
Lipase immobilized carbon nanotubes for conversion of Jatropha oil to fatty acid methyl esters
No full textLipase has been immobilized on multi-walled carbon nanotubes (MWCNTs) through the reaction of the carboxylated nanotubes with the enzyme in the presence of N-hydroxysulfosuccinimide (NHS) and 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride. Successful immobilization has been verified by infrared spectroscopy and scanning electron microscopy. The synthesized biomaterial has been used for catalyzing the conversion of Jatropha oil to the fatty acid methyl esters (FAME). Progress of the conversion reaction has been monitored with NIR spectroscopy. Gas chromatographic studies have indicated that the use of lipase–MWCNT bioconjuagate leads to almost quantitative conversion of Jatropha oil to the FAME. Around 1 h of the reaction, in the presence of around 15% of catalyst (mass fraction of catalyst on the total mixture), has yielded the desired results. The above used catalyst support has been regenerated 10 times without any adverse effect on the enzyme activity
Synthesis and Characterization of RADAR Absorbing BaFe12O19/ZnFe2O4 Magnetic Nanocomposite
No full textMagnetic composite comprising zinc ferrite and barium hexaferrite; BaFe12O19/ZnFe2O4 nanoparticles having super paramagnetic nature were synthesized by co-precipitation of iron, zinc and barium chloride salts using 7.5 M sodium hydroxide solution. The resulting precursors were heat treated (HT) at 800 and 1200°C for 4 h in nitrogen atmosphere. The hysteresis loops showed an increase in saturation magnetization from 1.040 to 52.938 emu/g with increasing heat treatment (HT) temperatures. The ‘as synthesized’ particles have size in the range of 20–22 nm with spherical and needle shapes. Further, these spherical and needle shaped nanoparticles tend to change their morphology to hexagonal plate shape with increase in HT temperatures. The effect of such a systematic morphological transformation of nanoparticles on microwave absorption properties were estimated in X band (8.2–12.2 GHz). The maximum reflection loss of the composite reaches-23.12 dB (more than 99% power attenuation) at 10.46 GHz which make it a potential material in the area of stealth technology
Automatic Landmark Identification in Lateral Cephalometric Images Using Optimized Template Matching
No full textCephalometric analysis has long helped researchers and orthodontic practitioners for evaluation of facial growth, understanding facial morphology and its ethnic variations, orthodontic diagnosis and treatment planning for patients presenting with malocclusion and dentofacial deformities. Mostly, inaccuracy in cephalometric measurements is a reflection of errors in identification and accurate localization of anatomical landmarks. The accuracy of landmark identification is greatly influenced by knowledge of the operator and experience. Moreover, the process of manual detection is tedious and time consuming. Therefore, a need for development of robust and accurate algorithms for automatic detection of landmarks on cephalometric images has been comprehended. In this work, we hereby propose an optimized template matching (OTM) algorithm which could automatically localize hard and soft tissue anatomical landmarks on lateral cephalometric images. This algorithm was tested for sixteen hard and eight soft tissue landmarks chosen in 12 regions on 37 lateral cephalograms obtained from subjects of either sex covering wide spectrum of malocclusion cases. The results of proposed automatic algorithm were compared to that of manual marking conducted by three experienced orthodontic specialists. All the 24 landmarks (100%) were detected within 3.0 mm error range of manual marking, 23 (96%) were detected within 2.5 mm error range and 16 (66.6%) landmarks were detected within 2.0 mm error range. The optimized template matching (OTM) algorithm may prove to be a promising approach in automatic detection of anatomical landmarks on cephalometric images
Structural and Ultrafast Charge Carrier Dynamics of in-situ synthesized rGO/Fe3O4Nanocomposite.
No full textThe work presents structural and charge carrier dynamics of in-situ synthesized rGO/Fe3O4 nanocomposite (NC). TEM and FT-IR measurements were used to probe structure and results show the uniform dispersion of Fe3O4 nanoparticles onto rGO matrix in NC. The first systematic measurements on charge carrier dynamics of this NC material was investigated using ultrafast spectroscopy, which portray the occurrence of electron transfer from rGO LUMO to Fe3O4 HOMO and testify GO position as an electron donor in NC. These results demonstrate the potential optical/electrochemical sensing applications of the formed NC material
Fabrication of ultrathin, free-standing, transparent and conductive graphene/multiwalled carbon nanotube film with superior optoelectronic properties
No full textHere we report a wet chemical technique to obtain transparent electrodes for optoelectronic devices. This technique is simple, facile, low cost and an effective way to prepare ultrathin free standing hybrid graphene/multiwalled carbon nanotubes (MWCNT) films. The graphene/MWCNT films, up to 36 mm in diameter, with controllable thickness and root mean square surface roughness of the order of 12.6 nm are prepared. The ratio of graphene/MWCNT is optimized to make them free standing and easily transferrable on various substrates. The ratio of direct current conductivity to the optical conductivity (σdc/σopt) which is considered as figure of merit for transparent conductors, is enhanced to 10.27 for graphene/MWCNT hybrid films. The prepared films showed outstanding transmittance up to 87.3 ± 1% at 550 nm, 87.9 ± 1% at 800 nm and sheet resistance of 136 ± 22.4 Ω/sq
Straight, conic and circular fringes in single interferogram
No full textInterferometry is an important part of optics courses taught at the undergraduate level in universities throughout the world. It is used to explain to students the wave nature of light and is also used to measure parameters like length, refractive index, thickness of test samples and wavelength of light source, etc. The shape of interference fringes (linear, conic or circular) gives vital information about the interfering wavefronts and is used for firsthand visual inspection in optical shop testing and other applications of scientific and engineering importance. The present work describes a simple laboratory technique to generate fringes with different shapes in a single interferogram. This is achieved by using our diffraction-Lloyd mirror interferometer where two portions of the diffracted field are superimposed to generate the interference fringes. The technique is quite helpful in explaining the role of source orientation on the shape of interference fringes to students
Index-based groundwater vulnerability mapping models using hydrogeological settings: A critical evaluation
No full textGroundwater vulnerability maps are useful for decision making in land use planning and water resource management. This paper reviews the various groundwater vulnerability assessment models developed across the world. Each model has been evaluated in terms of its pros and cons and the environmental conditions of its application. The paper further discusses the validation techniques used for the generated vulnerability maps by various models. Implicit challenges associated with the development of the groundwater vulnerability assessment models have also been identified with scientific considerations to the parameter relations and their selections
Time–frequency analysis based robust vehicle detection using seismic sensor
No full textThis paper presents a robust time–frequency approach based on pseudo-Wigner–Ville distribution assisted Rényi entropy (PWVD-RE) for vehicle detection. Seismic sensors are used to capture the ground vibrations generated by moving vehicles. One of the challenging tasks is to accurately localize a seismic event with minimal or no false alarm. PWVD gives the energy distribution of a non-stationary signal in the time–frequency plane. This energy distribution can be interpreted as probability density function (pdf). Rényi entropy is used as localized measure of the energy distribution. A higher value of entropy indicates the likehood of a possible seismic event. An optimized Constant False Alarm Rate (CFAR) detector is used for detection of events caused by moving vehicles. Experiments were performed with civilian vehicles for validation of the proposed method. The performance is compared with the classical spectrogram based approach. The results show significant improvement in false alarm rate and reasonable enhancement in detection rate
Force detection in real time machining process using machine condition monitoring system
No full textCutting is a process of extensive stresses and plastic deformations. The high compressive and frictional contact
stresses on the tool face result in a substantial cutting forces. Cutting forces are background for evaluation of
necessary power required for machining and for dimensioning of machine tool components. They influence the deformation of the work piece, its dimensional accuracy, chips formation and machining system stability. The direct approach to study cutting forces in machining is very expensive and time consuming, especially when a wide range of parameters like tool geometry, material, cutting conditions, etc are included. The study presents an attempt to estimate the cutting forces during turning and facing in real time constraints using condition
monitoring system for machine tool. The system is based on LabVIEW software, data acquisition system and strain gauges fixed on the cutting tool for measuring the cutting forces. Three levels of cutting parameters i.e. depth of cut, cutting speed and feed rate are chosen. The strain gauges measures the strain produced during machining and values are stored in the computer using data acquisition system. The system measures the experimental cutting forces by means of strain gauges fixed on cutting tool and developed calibration curve. The data obtained from the acquisition system was then compared with the calculated cutting forces values
PLC Based Sensor and Instrumentation for Crop Disease Forecasting System
No full text-The main idea of this paper is to present PLC
based data acquisition system for plant disease information to the farmers [4]. The objective of this paper is to develop a predictive model for early forecasting of disease severity for Picrorhiza kurroa and Apple with optimum efficiency, which help to farmers for management and control of use of pesticides to reduce the loss in economical cost and also beneficial to the environment and human health. Firstly, we measure different parameters like temperature, humidity, leaf
wetness, solar radiations etc. by use of different sensors. The output analogous signal is applied to the PLC system for data processing by use of predefined mathematical model. The System can detect the small fluctuations in parameters and compare it with past data values to make a decision. PLC uses a different type of programming like ladder, Boolean, Grafcet for implementing a mathematical model [2]. Due to which we
will have a complete understanding of the environmental
conditions of Apple and Picrorhiza kurroa farms and we
would thus able to control these conditions. By use of this data, we can also implement such automatic systems which detect the symptoms of disease at starting stage and perform an action accordingly and spray the pesticides in a control manner without interaction of human [3]. By correlating the plant indices we can provide a valuable information to farmers
for improving quality and quantity of crops