A subalgebra of the Hardy algebra relevant in control theory and its algebraic-analytic properties

We denote by A_0+AP_+ the Banach algebra of all complex-valued functions f defined in the closed right half plane, such that f is the sum of a holomorphic function vanishing at infinity and a ``causal'' almost periodic function. We give a complete description of the maximum ideal space M(A_0+AP_+) of A_0+AP_+. Using this description, we also establish the following results: (1) The corona theorem for A_0+AP_+. (2) M(A_0+AP_+) is contractible (which implies that A_0+AP_+ is a projective free ring). (3) A_0+AP_+ is not a GCD domain. (4) A_0+AP_+ is not a pre-Bezout domain. (5) A_0+AP_+ is not a coherent ring. The study of the above algebraic-anlaytic properties is motivated by applications in the frequency domain approach to linear control theory, where they play an important role in the stabilization problem.Comment: 17 page

Adaptive Channel Coding and Modulation Scheme Selection for Achieving High Throughput in Wireless Networks

Modern wireless communication demands reliable data communication at high throughput in severe channel conditions like narrowband interference, frequency selective fading due to multipath and attenuation of high frequencies. Traditional single carrier systems address this set of problems by the use of complex, computationally intensive equalization filters. The Orthogonal Frequency Division Multiplexing (OFDM) based system, as opposed to single-carrier systems, is considered to be the future of the wireless communication and is being used to achieve high data rate by overcoming severe channel conditions without the use of these complex filters.This paper discusses the problem of Adaptive Modulation scheme selection through an OFDM based system over parallel frequency selective fading channels. An adaptive coding scheme is proposed by using Generalized Concatenated Codes (GCC), which have simple structure and are designed in such a way that they are best suited for fading channels. GCC are based on binary cyclic codes. The criterion of the proposed research is to optimize the throughput of a wireless system. Depending on the quality of sub-channels an adaptive modulation selection scheme and code assigning method is proposed. The proposed research combats against channel impairments better than those used in conventional systems by exploiting individual sub-channel condition. Results show better performance in terms of higher throughput by minimizing the bit error rate

DEVELOPMENT AND VALIDATION STABILITY INDICATING HPTLC METHOD FOR DETERMINATION OF VILDAGLIPTIN AND METFORMIN HYDROCHLORIDE IN THE PHARMACEUTICAL DOSAGE FORMS

Objective: A simple, precise, and accurate stability indicating high-performance thin layer chromatography method was developed and validated of vildagliptin (VIL) and metformin (MET) in pharmaceutical dosage forms.Methods: In the present study, system suitability test, stress study, alkali hydrolysis, acid hydrolysis, neutral hydrolysis, oxidative stress degradation, dry heat degradation, wet heat degradation, photodegradation study has been used. In this method, optimization by changing various parameters, such as organic solvent and the composition of the mobile phase, acid or base modifier used in the mobile phase; by varying one parameter and keeping all other conditions constant. 10 µl of the stock solution for MET (500 ng/band) and 2 µl of the stock solution for VIL (100 ng/band) were applied to TLC plates. The final solutions were applied on the HPTLC plates and these were developed as per the optimized densitometry conditions.Results: From the spectra, it was observed that MET and VIL exhibited good absorbance at about 217 nm. Both the drugs showed degradation with additional peaks at Rfvalues of 0.16 for MET and with Rfvalues 0.81 for VIL respectively. The method was validated for linearity, precision, accuracy, limit of detection, limit of quantification, ruggedness, specificity, and robustness. Good separation was achieved by using the mobile phase Hexane: Methanol: Acetonitrile: Glacial Acetic Acid (2:3.5:2.5:0.2 v/v/v/v) with retardation factor (Rf) values of 0.22±0.01 for MET and 0.73±0.02 for VIL.Conclusion: A validated HPTLC method was developed for the determination of metformin hydrochloride and vildagliptin. The method is simple, quick, and can be applied routinely for the analysis of these drugs from marketed dosage forms

Contactless digital tachometer using microcontroller

Tachometer is a device that used for counting or for the measuring purpose of the number of revolutions (that is the total number rotations made by the device in unit of measuring time) of an object in unit time. It is expressed in the unit of RPS or RPM, the model uses a set of infrared transducer receiver to count the RPM pulses, and the Arduino microcontroller is used for the implementation of the project. The individual pulses are counted by the microcontroller to give the final output of the RPM

An Integrated Neuronal Model of Claustral Function in Timing the Synchrony Between Cortical Areas

It has been suggested that the function of the claustrum (CL) may be to orchestrate and integrate the activity of the different cortical areas that are involved in a particular function by boosting the synchronized oscillations that occur between these areas. We propose here a model of how this may be done, thanks to the unique synaptic morphology of the CL and its excitatory and inhibitory connections with most cortical areas. Using serial visual search as an example, we describe how the functional anatomy of the claustral connections can potentially execute the sequential activation of the representations of objects that are being processed serially. We also propose that cross-frequency coupling (CFC) between low frequency signals from CL and higher frequency oscillations in the cortical areas will be an efficient means of CL modulating neural activity across multiple brain regions in synchrony. This model is applicable to the wide range of functions one performs, from simple object recognition to reading and writing, listening to or performing music, etc

Extreme mechanical resilience of self-assembled nanolabyrinthine materials

Low-density materials with tailorable properties have attracted attention for decades, yet stiff materials that can resiliently tolerate extreme forces and deformation while being manufactured at large scales have remained a rare find. Designs inspired by nature, such as hierarchical composites and atomic lattice-mimicking architectures, have achieved optimal combinations of mechanical properties but suffer from limited mechanical tunability, limited long-term stability, and low-throughput volumes that stem from limitations in additive manufacturing techniques. Based on natural self-assembly of polymeric emulsions via spinodal decomposition, here we demonstrate a concept for the scalable fabrication of nonperiodic, shell-based ceramic materials with ultralow densities, possessing features on the order of tens of nanometers and sample volumes on the order of cubic centimeters. Guided by simulations of separation processes, we numerically show that the curvature of self-assembled shells can produce close to optimal stiffness scaling with density, and we experimentally demonstrate that a carefully chosen combination of topology, geometry, and base material results in superior mechanical resilience in the architected product. Our approach provides a pathway to harnessing self-assembly methods in the design and scalable fabrication of beyond-periodic and nonbeam-based nano-architected materials with simultaneous directional tunability, high stiffness, and unsurpassed recoverability with marginal deterioration

Information Processing view of Electricity Demand Response Systems: A Comparative Study Between India and Australia

Background: In recent years, demand response (DR) has gained increased attention from utilities, regulators, and market aggregators to meet the growing demands of electricity. The key aspect of a successful DR program is the effective processing of data and information to gain critical insights. This study aims to identify information processing needs and capacity that interact to improve energy DR effectiveness. To this end, organizational information processing theory (OIPT) is employed to understand the role of Information Systems (IS) resources in achieving desired DR program performance. This study also investigates how information processing for DR systems differ between developing (India) and developed (Australia) countries. Method: This work adopts a case study methodology to propose a theoretical framework using OIPT for information processing in DR systems. The study further employs a comparative case data analyses between Australian and Indian DR initiatives. Results: Our cross case analysis identifies variables of value creation in designing DR programs - pricing structure for demand side participation, renewable integration at supply side, reforms in the regulatory instruments, and emergent technology. This research posits that the degree of information processing capacity mediates the influence of information processing needs on energy DR effectiveness. Further, we develop five propositions on the interaction between task based information processing needs and capacity, and their influence on DR effectiveness. Conclusions: The study generates insights on the role of IS resources that can help stakeholders in the electricity value chain to take informed and intelligent decisions for improved performance of DR programs

Importance of Synthetic Flocculants in Alumina Industry

In the Bayer's process of alumina production, separation of mud residue front the liquor plays on important role. Throughout Alumina production process additives are used at one stage or the other, flocculant being one of the additives. Till 70's natural flocculants were used in the operations. Starch, guar gum, wheat bran etc. were used for the purpose of settling of red mud and to attain increased solidl/liquid separation rates. Slowly transformation has taken place from natural flocculants to synthetic flocculattts for a variety of advantages such as improved settling rates, improved liquor throughput, high underflow consistency,improved liquor filterability, reduced organic load etc. They also control the physical and chemical properties of the Bayer process streams during the operation- Synthetic flocculattts are polymers of acrylamide & polvac rylate etc. the molecular structure of which is an important factor to obtain the desired flocculation effect in the process liquors. Depending on the Bauxite quality and the process technology adopted the selection of flocculant varies from plant to plant. This paper deals with different types of synthetic flocculants available, their usage in Alumina industry

Controlling Surface Potential of Graphene Using dc Electric Field

In this work, we study surface potential of graphite deposited on SiO2/Si substrate using Kelvin Probe Force Microscopy (KPFM) and Electric Force Microscopy (EFM). The amplitude modulated KPFM (AM-KPFM) shows that the graphene layer work function is 4.69±0.02 eV, whereas frequency modulated KPFM (FM-KPFM) revealed 4.50±0.02 eV. The work function indifference of 0.19±0.02 eV was attributed to the superior resolution of FM-KPFM and higher detection sensitivity of AM-KPFM. Subsequent EFM mapping suggests that the phase monotonically increases with increasing applied dc bias voltage in the range from -5 V to 5 V. This phase shift is ascribed to the induced charge polarization at tip-graphene surface due to interatomic interactions induced by dc field effects

Quantitative measurement of blood flow in paediatric brain tumours. A comparative study of dynamic susceptibility contrast and multi-timepoint arterial spin-labelled MRI

OBJECTIVE: Arterial spin-labelling (ASL) MRI uses intrinsic blood water to quantify the cerebral blood flow (CBF), removing the need for the injection of a gadolinium-based contrast agent used for conventional perfusion imaging such as dynamic susceptibility contrast (DSC). Owing to the non-invasive nature of the technique, ASL is an attractive option for use in paediatric patients. This work compared DSC and multi-timepoint ASL measures of CBF in paediatric brain tumours. METHODS: Patients (n = 23; 20 low-grade tumours and 3 high-grade tumours) had DSC and multi-timepoint ASL with and without vascular crushers (VC). VC removes the contribution from larger vessel blood flow. Mean perfusion metrics were extracted from control and T(1)-enhanced tumour regions of interest (ROIs): arterial arrival time (AAT) and CBF from the ASL images with and without VC, relative cerebral blood flow (rCBF), relative cerebral blood volume, delay time (DT) and mean transit time (MTT) from the DSC images. RESULTS: Significant correlations existed for: AAT and DT (r = 0.77, p = 0.0002) and CBF and rCBF (r = 0.56, p = 0.02) in control ROIs for ASL-noVC. No significant correlations existed between DSC and ASL measures in the tumour region. Significant differences between control and tumour ROI were found for MTT (p < 0.001) and rCBF (p < 0.005) measures. CONCLUSION: Significant correlations between ASL-noVC and DSC measures in the normal brain suggest that DSC is most sensitive to macrovascular blood flow. The absence of significant correlations within the tumour ROI suggests that ASL is sensitive to different physiological mechanisms compared with DSC measures. ADVANCES IN KNOWLEDGE: ASL provides information which is comparable with that of DSC in healthy tissues, but appears to reflect a different physiology in tumour tissues