Novel observers for compensation of communication delay in bilateral control systems

The problem of communication delay in bilateral or teleoperation systems is even more emphasized with the use of the internet for communication, which may give rise to loss of transparency and even instability. To address the problem, numerous methods have been proposed. This study is among the few recent studies taking a disturbance observer approach to the problem of time delay, and introduces a novel sliding-mode observer to overcome specifically the effects of communication delay in the feedback loop. The observer operates in combination with a PD+ controller which controls the system dynamics, while also compensating load torque uncertainties on the slave side. To this aim, an EKF based load estimation algorithm is performed on the slave side. The performance of this approach is tested with computer simulations for the teleoperation of a 1-DOF robotic arm. The simulations reveal an acceptable amount of accuracy and transparency between the estimated slave and actual slave position under both constant and random measurement delay and variable and step-type load variations on the slave side, motivating the use of the approach for internet-based bilateral control systems

ANTI-INFLAMMATORY, CYTOTOXIC AND ANTIOXIDANT EFFECTS OF METHANOLIC EXTRACTS OF DRYPETES SEPIARIA (EUPHORBIACEAE)

Abstract The aim of this study was to investigate in vitro antioxidant, anti-inflammatory and cytotoxic activities of the petroleum ether, ethyl acetate, methanol and aqueous extracts obtained from leaves of Drypetes sepiaria (Euphorbiaceae). Total phenolic and flavonoid contents of these crude extracts were determined as gallic acid and quercetin equivalents, respectively. In in vitro antioxidant method, methanol extract exhibited higher free radical scavenging activity compared to standard compound, ascorbic acid with IC 50 of 95.43µg/ml (DPPH) and 67.05µg/ml (ABTS). Methanol extract was able to inhibit inflammation by in vitro about 85-90% (HRBC stabilization method) and in vivo about 40-45% (Paw oedema method) anti-inflammatory assays compared to standard produced 50.04% at 6h period. In cytotoxicity assay (MTT assay) methanolic extract exhibited IC 50 of 10µg/ml. In apoptosis (flow cytometric assay), the control group showed normal caspase 3 activity in the SiHa cells which was 0.24%, and increased up to 40% after treatment

ANTI-INFLAMMATORY, CYTOTOXIC AND ANTIOXIDANT EFFECTS OF METHANOLIC EXTRACTS OF DRYPETES SEPIARIA (EUPHORBIACEAE)

The aim of this study was to investigate in vitro anti-oxidant, anti-inflammatory and cytotoxic activities of the petroleum ether, ethyl acetate, methanol and aqueous extracts obtained from leaves of Drypetes sepiaria (Euphorbiaceae). Total phenolic and flavonoid contents of these crude extracts were determined as gallic acid and quercetin equivalents, respectively. In in vitro antioxidant method methanol extract exhibited higher free radical scavenging activity compared to standard compound, ascorbic acid with IC50 of 95.43µg/ml (DPPH) and 67.05µg/ml (ABTS). Methanol extract was able to inhibit inflammation by in vitro about 85-90% (HRBC stabilization method) and in vivo about 40-45% (Paw edema method) anti-inflammatory assays compared to standard produced 50.04% at 6h period. In cytotoxicity assay (MTT assay) methanolic extract exhibited IC50 of 10µg/ml. In apoptosis (flow cytometric assay), the control group showed normal caspase 3 activity in the SiHa cells which was 0.24% and increased up to 40% after treatment

ECDSA-Based Water Bodies Prediction from Satellite Images with UNet

The detection of water bodies from satellite images plays a vital role in research development. It has a wide range of applications such as the prediction of natural disasters and detecting drought and flood conditions. There were few existing applications that focused on detecting water bodies that are becoming extinct in nature. The dataset to train this deep learning model is taken from Kaggle. It has two classes, namely water bodies and masks. There is a total of 2841 sentinel-2 satellite images with corresponding 2841 masks. Additionally, the present work focuses on using UNet, Tensorflow to detect the water bodies. It uses a Nadam optimizer to reduce the losses. It also finds best-optimized parameters for the activation function, a number of nodes in each layer. This proposed model achieves integrity by embedding a security feature Elliptic Curve Digital Signature Algorithm (ECDSA). It generates a digital signature for the predicted area of water bodies which helps to secure the key and the detected water bodies while transmitting in a channel. Thus, the proposed model ensures the performance accuracy of 94% which can also work the same for edge detection, detection in blurred and low-resolution images. The model is highly robust

Hash-Based Deep Learning Approach for Remote Sensing Satellite Imagery Detection

Ship detection plays a crucial role in marine security in remote sensing imagery. This paper discusses about a deep learning approach to detect the ships from satellite imagery. The model developed in this work achieves integrity by the inclusion of hashing. This model employs a supervised image classification technique to classify images, followed by object detection using You Only Look Once version 3 (YOLOv3) to extract features from deep CNN. Semantic segmentation and image segmentation is done to identify object category of each pixel using class labels. Then, the concept of hashing using SHA-256 is applied in conjunction with the ship count and location of bounding box in satellite image. The proposed model is tested on a Kaggle Ships dataset, which consists of 231,722 images. A total of 70% of this data is used for training, and the 30% is used for testing. To add security to images with detected ships, the model is enhanced by hashing using SHA-256 algorithm. Using SHA-256, which is a one-way hash, the data are split up into blocks of 64 bytes. The input data to the hash function are both the ship count and bounding box location. The proposed model achieves integrity by using SHA-256. This model allows secure transmission of highly confidential images that are tamper-proof

Application of sulfonimidoyl substituted allyltitanium (IV) complexes to the asymmetric synthesis of alkenyloxiranes, 2,3-dihydrofurans, tetrahydrofurans, unsaturated proline analogues and allylic alcohols

An asymmetric synthesis of 3-substituted unsaturated proline derivatives starting from the g,d-unsaturated a-amino acids is described in chapter 3. Amino acid derivatives were obtained through aminoalkylation of the sulfoximine substituted allyl (trisdiethylamino) titanium (IV) complexes with the N-tert-butylsulfonyl imino ester. Activation of sulfoximines through methylation, of the sulfoximine group follwed by Cl substitution, and subsequent DBU-mediated, intramolecular, nucleophilic substitution afforded the optically-pure proline derivatives in medium to high yields. An asymmetric synthesis of allylic alcohols from allylic sulfoximines and aldehydes is described in chapter 4. Lithiation and titanation of cyclic and acyclic allylic sulfoximines with ClTi(NEt2)3 and subsequent treatment with aldehydes gave, as described previously, enantio- and diastereomerically-pure, syn-configured, sulfoximine-substituted homoallylic alcohols. Treatment of these alcohols with n-BuCu resulted in a SN2¢ reaction, and delivered a enantio- and diastereomerically-pure allylic alcohols. An asymmetric synthesis of cycloalkenyl and alkenyloxiranes from allylic sulfoximines and aldehydes is described in chapter 1. Lithiation and titanation of cyclic and acyclic allylic sulfoximines with ClTi(NEt2)3 and subsequent treatment with aldehydes gave, as described previously, enantio- and diastereomerically pure, syn-configured, sulfoximine-substituted homoallylic alcohols with ClCO2CH(Cl)Me resulted in a facile substitution of the sulfoximine group by a Cl atom, with formation of the corresponding alkenyl chlorohydrins. In the case of the cycloalkenyl derivatives the substitution proceeded with high diastereoselectivities and retention of configuration, while in the case of the alkenyl derivatives, medium diastereoselectivities with invertion of configuration were observed. An asymmetric synthesis of 2,3-dihydrofurans and of unsaturated bicyclic tetrahydrofurans from allylic sulfoximines and aldehydes is described in chapter 2

Application of sulfonimidoyl substituted allyltitanium (IV) complexes to the asymmetric synthesis of alkenyloxiranes, 2,3-dihydrofurans, tetrahydrofurans, unsaturated proline analogues and allylic alcohols

An asymmetric synthesis of 3-substituted unsaturated proline derivatives starting from the g,d-unsaturated a-amino acids is described in chapter 3. Amino acid derivatives were obtained through aminoalkylation of the sulfoximine substituted allyl (trisdiethylamino) titanium (IV) complexes with the N-tert-butylsulfonyl imino ester. Activation of sulfoximines through methylation, of the sulfoximine group follwed by Cl substitution, and subsequent DBU-mediated, intramolecular, nucleophilic substitution afforded the optically-pure proline derivatives in medium to high yields. An asymmetric synthesis of allylic alcohols from allylic sulfoximines and aldehydes is described in chapter 4. Lithiation and titanation of cyclic and acyclic allylic sulfoximines with ClTi(NEt2)3 and subsequent treatment with aldehydes gave, as described previously, enantio- and diastereomerically-pure, syn-configured, sulfoximine-substituted homoallylic alcohols. Treatment of these alcohols with n-BuCu resulted in a SN2¢ reaction, and delivered a enantio- and diastereomerically-pure allylic alcohols. An asymmetric synthesis of cycloalkenyl and alkenyloxiranes from allylic sulfoximines and aldehydes is described in chapter 1. Lithiation and titanation of cyclic and acyclic allylic sulfoximines with ClTi(NEt2)3 and subsequent treatment with aldehydes gave, as described previously, enantio- and diastereomerically pure, syn-configured, sulfoximine-substituted homoallylic alcohols with ClCO2CH(Cl)Me resulted in a facile substitution of the sulfoximine group by a Cl atom, with formation of the corresponding alkenyl chlorohydrins. In the case of the cycloalkenyl derivatives the substitution proceeded with high diastereoselectivities and retention of configuration, while in the case of the alkenyl derivatives, medium diastereoselectivities with invertion of configuration were observed. An asymmetric synthesis of 2,3-dihydrofurans and of unsaturated bicyclic tetrahydrofurans from allylic sulfoximines and aldehydes is described in chapter 2

SINGLE CELL MANIPULATION BY FEMTOSECOND LASERS AND VOLUMETRIC ANALYSIS OF CONVECTION ENHANCED DRUG DELIVERY

Optoporation allows the minimal invasive transfer of extracellular molecules into cells. The use of a low repetition rate laser system (100 fs at 790 nm and 1 kHz repetition rate) can enable the future transfer of this technique to in vivo applications. However, it is essential to understand the biophysical parameter space of this technique beforehand. We examined the optoporation dependence on the extracellular calcium concentration in HeLa cells. We observed a low cell recovery rate in calcium free medium and varying cell viabilities with different calcium concentrations, possibly related to calcium dependent repair processes. Also we followed the calcium rise in the cell by a fluorescent calcium indicator. We extended our previous model of pore formation model and applied different sized dextrans to verify our assumptions on pore radius, and resealing time. Therefore, this study provides a better understanding of the biophysical processes accompanying single cell laser transfection. Drug delivery into the brain is inhibited by the blood brain barrier and limited by the structure of the brain interstitium. Convection-enhanced delivery (CED) is a technique that delivers therapeutics by infusing directly into brain parenchyma through a needle inserted into the brain. We developed a fast scanning, real time volumetric imaging platform to image transport of nanoparticles in the rat cortex in vivo with high temporal and spatial resolution and to study transport mechanisms for different sized nanoparticles in the brain interstitium and the perivascular space (PVS). Fluorescent polystyrene beads of sizes ranging from 20nm to 200nm were infused directly into a rat cortex. Particles sized >100nm had distribution routes along the perivascular spaces and were relatively hindered in the extracellular spaces in comparison to particles in the 20nm – 40nm size range that prefered transport in extracellular space. Thus, we can study the alterations in the shape, size and movement of the infusion in the brain, allowing for better control for potential clinical design and optimization

Learning a common dictionary for CSI feedback in FDD massive MU-MIMO-OFDM systems

In a transmit preprocessing aided frequency division duplex (FDD) massive multi-user (MU) multiple-input multiple-output (MIMO) scheme assisted orthogonal frequency-division multiplexing (OFDM) system, it is required to feed back the frequency domain channel transfer function (FDCHTF) of each subcarrier at the user equipment (UE) to the base station (BS). The amount of channel state information (CSI) to be fed back to the BS increases linearly with the number of antennas and subcarriers, which may become excessive. Hence we propose a novel CSI feedback compression algorithm based on compressive sensing (CS) by designing a common dictionary (CD) to reduce the CSI feedback of existing algorithms. Most of the prior work on CSI feedback compression considered single-UE systems. Explicitly, we propose a common dictionary learning (CDL) framework for practical frequency-selective channels and design a CD suitable for both single-UE and multi-UE systems. A set of two methods is proposed. Specifically, the first one is the CDL-K singular value decomposition (KSVD) method, which uses the K-SVD algorithm. The second one is the CDL-orthogonal Procrustes (OP) method, which relies on solving the orthogonal Procrustes problem. The CD conceived for exploiting the spatial correlation of channels across all the subcarriers and UEs compresses the CSI at each UE, and upon reception reconstructs it at the BS. Our simulation results show that the proposed dictionary’s estimated channel vectors have lower normalized mean-squared error (NMSE) than the traditional fixed Discrete Fourier Transform (DFT) based dictionary. The CSI feedback is reduced by 50%, and the memory reduction at both the UE and BS starts from 50% and increases with the number of subcarriers