38 research outputs found
Higher order feature extraction and selection for robust human gesture recognition using CSI of COTS Wi-Fi devices
Device-free human gesture recognition (HGR) using commercial o the shelf (COTS) Wi-Fi
devices has gained attention with recent advances in wireless technology. HGR recognizes the human
activity performed, by capturing the reflections ofWi-Fi signals from moving humans and storing
them as raw channel state information (CSI) traces. Existing work on HGR applies noise reduction
and transformation to pre-process the raw CSI traces. However, these methods fail to capture
the non-Gaussian information in the raw CSI data due to its limitation to deal with linear signal
representation alone. The proposed higher order statistics-based recognition (HOS-Re) model extracts
higher order statistical (HOS) features from raw CSI traces and selects a robust feature subset for the
recognition task. HOS-Re addresses the limitations in the existing methods, by extracting third order
cumulant features that maximizes the recognition accuracy. Subsequently, feature selection methods
derived from information theory construct a robust and highly informative feature subset, fed as
input to the multilevel support vector machine (SVM) classifier in order to measure the performance.
The proposed methodology is validated using a public database SignFi, consisting of 276 gestures
with 8280 gesture instances, out of which 5520 are from the laboratory and 2760 from the home
environment using a 10 5 cross-validation. HOS-Re achieved an average recognition accuracy of
97.84%, 98.26% and 96.34% for the lab, home and lab + home environment respectively. The average
recognition accuracy for 150 sign gestures with 7500 instances, collected from five di erent users was
96.23% in the laboratory environment.Taylor's University through its TAYLOR'S PhD SCHOLARSHIP Programmeinfo:eu-repo/semantics/publishedVersio
Sign language gesture recognition with bispectrum features using SVM
Wi-Fi based sensing system captures the signal reflections due to human gestures as Channel State Information (CSI) values in subcarrier level for accurately predicting the fine-grained gestures. The proposed work explores the Higher Order Statistical (HOS) method by deriving bispectram features (BF) from raw signal by adopting a Conditional Informative Feature Extraction (CIFE) technique from information theory to form a subset of informative and best features. Support Vector Machine (SVM) classifier is adopted in the present work for classifying the gesture and to measure the prediction accuracy. The present work is validated on a secondary dataset, SignFi, having data collected from two different environments with varying number of users and sign gestures. SVM reports an overall accuracy of 83.8%, 94.1%, 74.9% and 75.6% in different environments/scenarios.Taylor's University through its TAYLOR'S PhD SCHOLARSHIP Programmeinfo:eu-repo/semantics/publishedVersio
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Dynamic and Reactivity of Guests Within a Water-Soluble Hosts and Synthesis of Cationic Water-Soluble Cavitands.
The research presented in this thesis is a consolidated account of NMR and photochemical reactions carried in a water-soluble cavitand, called octa acid. In buffered aqueous solutions, octa acid forms stable complexes with different guest molecules. Product selectivity as a result of modification of the substituent forms the primary concept in each chapter. Chapter 1 introduces the concept of supramolecular chemistry and supramolecular photochemistry with some examples from various research groups. The role of self-assembled cavitands as hosts for reactions is discussed specifically. Structure and properties of the cavitand used in this work termed octa acid (OA) and octa diethyl amine are presented along with some published results. A brief outline of the NMR techniques (COSY, DQF-COSY, NOESY, PGSE and DOSY) used to study the self-assembled complexes formed between hosts and guests analyzed is presented. Synthesis and characterization of newly synthesized water soluble cavitands (octa diethyl amine, OAM and octa triethyl ammonium iodide, OTEAM) are explained in chapter 2. Complexation behavior of various guest molecules, the excited state behavior of these guests within the capsular assembly of OAM and OTEAM are studied in detail. Natures of complexes formed were analyzed by NMR spectroscopy. The complexes formed by the OAM as host and any guest molecules are shown to be stable in the gas phase, confirmed by ESI-MS studies. An attempt to synthesize the gold nanoparticles stabilized with OAM cavity is also explained. Dynamic behavior of guest molecules within the host OA probed by various NMR techniques are discussed in chapter 3. The guest molecule that is imprisoned within a host is not stationary. The extent of freedom is dependent on weak interactions that hold the guest within the container. The mobility of the guest within the host is dictated by the free volume in host and the structure of the guest by itself. Chapter 4 is comprised of the results from studies Norrish Type I and Type II photochemistry of optically pure α-alkyl deoxybenzoins within the OA capsular assembly. The product distribution is different from that in an organic solvent was also dependent on the nature of the α-alkyl chain. The communication between incarcerated optically pure α-alkyl deoxybenzoins and molecules in the bulk solvent controlled by supramolecular factors such as coloumbic attraction and repulsion between a charged guest@host complex and charged molecules in the bulk aqueous phase is explained Chapter 5 compares the photochemistry of alkyl aryl ketones bound to octa acid to their reaction and in homogeneous solutions. 1D and 2D NMR analysis of the complexes formed between the ketones and octa acid are provided. Nature of host-guest assembly is revealed by the NMR analysis. Photochemical results shows enhanced selectivity, particularly in the case of cyclic alkyl aryl ketones which is due to its preferred orientation that is confirmed by molecular dynamics stud
New water-soluble organic capsules are effective in controlling excited-state processes of guest molecules
Synthesis, inclusion properties, and ability to control excited-state properties of two water-soluble hosts are presented. These hosts surround the guest molecule(s) by forming a capsular assembly. By constraining the guest and by providing very little free space, the host is able to alter the excited-state behavior of guest molecules. The excited-state chemistry and physics of guest molecules are distinctly different from those in organic solvents
Experimental study of developing turbulent flow and heat transfer in ribbed convergent/divergent rectangular ducts
The article represents an experimental investigation of friction and heat transfer characteristics of divergent / convergent rectangular ducts with an inclination angle of 1Ëš in the y-axis. Measurements were taken for a convergent / divergent rectangular duct of aspect ratio AR at inlet1.25 and outlet in convergent channel 1.35; but in case of divergent duct it can be reversed. The four uniform rib heights, e = 3, 6, 9 and 12 mm the ratio between rib height to hydraulic mean diameter (e/Dm) are 34.8, 69.7, 104.6 and 138.7 a constant rib pitch distance, P = 60 mm has been used. The flow rate in terms of average Reynolds number based on the hydraulic mean diameter (Dm) is 86 mm of the channel was in a range of 20,000 to 50,000. The two ceramic heating strip of 10 mm thickness is used as a heating element have attached on top and bottom surfaces for the test sections. The heat transfer performance of the divergent / convergent ducts for 3, 6, 9 and 12 mm ribs was conducted under identical mass flow rate based on the Reynolds number. In our experiments has totally 8 different ducts were used. In addition, the acceleration / deceleration caused by the cross section area, the divergent duct generally shows enhanced heat transfer behavior for four different rib sizes, while the convergent duct has an appreciable reduction in heat transfer performance. From result point view divergent duct with 3 mm height ribbed square duct gets maximum heat transfer coefficient with minimum friction loss over the other convergent / divergent ducts
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Role of supramolecular steric compression during photoinduced intramolecular hydrogen abstraction reactions of ketones and thioketones
Excited state behavior of molecules is influenced by the environment in which they are present. The influence of solvents on reactions is understood in terms of the bulk properties of the solvent such as polarity, polarizability, hydrogen bonding, solvophobic interactions etc. Under these conditions, the 'space' surrounding the guest does not play any role in influencing the fate of an excited molecule. The current study focusses on understanding the factors that control the excited state reactivity of molecules within a confined space. In this context organic capsules assembled from two molecules of octa acid serves as the host and aryl alkyl ketones and aryl alkyl thioketones as reactive guests. One obvious prediction has been when the product is larger in size than the host capsule it would not be formed within the confined space although this may be the predominant product in solution. The authors demonstrate below that even if the product fits well within the capsule it may not be formed if the intermediate structures that connects the reactant to product does not fit within the capsule. The above hidden factor that controls photoproduct distribution has been investigated employing several aryl alkyl ketones that undergo gamma-hydrogen abstraction as guests. In some of the examples investigated here, the Yang cyclization product, cyclobutanol, is suppressed within OA capsule even though it fits well within the capsule. Another factor that has come to light is 'time'. Aryl alkyl thioketones that react from short lived second excited state (S2) fail to undergo delta-hydrogen abstraction within OA capsule although this is the only photoreaction in solution. MD simulations of the thioketones suggest that within the capsule the relevant hydrogens are not within the ideal geometry required for abstraction. Lack of reactivity is attributed to the insufficient time for the excited molecule to achieve the required conformation within the narrow space. Longer lived aryl alkyl ketones had no such problems in adopting a conformation required for hydrogen abstraction. Obviously, time becomes critical when the space is narrow. The results reported here brings out that one could consider 'free space' and 'time' as valuable tools to control product distribution while performing photochemistry in supramolecular assemblies
Influence of turbulence models on the performance prediction of flow through curved vane demisters
Two dimensional computational analyses with different turbulence models is carried out for the flow of single phase fluid (air) through curved vane demisters, as used in desalination plants. Computations are performed on a demister geometry, on which experiments were conducted and reported earlier. The experimental data contains local variations of velocity components measured, along chosen lines within the flow domain. Computational fluid dynamics results along these lines for 15 different turbulence models, using Ansys Fluent, were compared with experimental data. Present results indicated that the higher order wall treatment options, like enhanced wall treatment and non-equilibrium wall functions do not yield good predictions for the geometry currently studied. Few turbulence models were found to show better agreement levels, other than the Reynolds stress transport model, which is reported best for this type of geometry. It was found that Spalart–Almaras (SA) model and few variations of k–ε model showed better prediction than other models like k–ω. Considering the merits of accuracy in predicting local flow features in most of the locations, the SA model is recommended for analysis involving curved demister. Similar analysis can be extended for two phase flow through curved vane demisters, to understand the performance and suitabilit