This survey attempts to provide a comprehensive and structured overview of the existing research for the problem of detecting anomalies in discrete/symbolic sequences. The objective is to provide a ...global understanding of the sequence anomaly detection problem and how existing techniques relate to each other. The key contribution of this survey is the classification of the existing research into three distinct categories, based on the problem formulation that they are trying to solve. These problem formulations are: 1) identifying anomalous sequences with respect to a database of normal sequences; 2) identifying an anomalous subsequence within a long sequence; and 3) identifying a pattern in a sequence whose frequency of occurrence is anomalous. We show how each of these problem formulations is characteristically distinct from each other and discuss their relevance in various application domains. We review techniques from many disparate and disconnected application domains that address each of these formulations. Within each problem formulation, we group techniques into categories based on the nature of the underlying algorithm. For each category, we provide a basic anomaly detection technique, and show how the existing techniques are variants of the basic technique. This approach shows how different techniques within a category are related or different from each other. Our categorization reveals new variants and combinations that have not been investigated before for anomaly detection. We also provide a discussion of relative strengths and weaknesses of different techniques. We show how techniques developed for one problem formulation can be adapted to solve a different formulation, thereby providing several novel adaptations to solve the different problem formulations. We also highlight the applicability of the techniques that handle discrete sequences to other related areas such as online anomaly detection and time series anomaly detection.
Quasi-one dimensional spin chain compound, Ca3Co2O6, undergoes field and temperature induced dimensionality crossover at about 25 K from one-dimension to three-dimensionally correlated state. It is ...shown that interplay of intrachain and interchain couplings with thermal energy in this infinite spin chain system is responsible for this phenomenon. It is established from the measurement of temperature dependent magnetic susceptibility and field dependence of magnetization along different crystallographic axes of the single crystal. Further, the effect of chain truncation on dimensionality crossover has been studied to substantiate the role of these interactions in this phenomenon. Reduction of chain length causes decrease of the effective intrachain coupling strength without affecting the interaction of neighbouring chains significantly. As a result, the propensity of dimensional crossover is found to be weaker in the broken chain compared to the longer chain.
While unhealthy diet, tobacco, alcohol, and sedentary lifestyle are known determinants of NCDs,1 a meta-analysis suggests social isolation as a risk factor for coronary heart disease (CHD) and ...stroke. Improving population health in a vast and diverse country like India requires reliable and state level estimates of disease trends and risk factors. ...while allocating resources, NCDs cannot be considered in isolation. Data integration and creation of large social, environmental, and clinical data sets will increasingly play an important role of surveillance and monitoring as well as health technology assessment (HTA) in India.
When patients present with cavities causing pain, poor aesthetics and/or functional problems restorations will need to be placed. Minimally invasive caries excavation strategies can be deployed ...depending on the patient's caries risk, lesion-pulp proximity and vitality, the extent of remaining supra-gingival tooth structure and clinical factors (for example, moisture control, access). Excavation instruments, including burs/handpieces, hand excavators, chemo-mechanical agents and/or air-abrasives limiting caries removal selectively to the more superficial caries-infected dentine and partial removal of caries-affected dentine when required, help create smaller cavities with healthy enamel/dentine margins. Using adhesive restorative materials the operator can, if handling with care, optimise the histological substrate coupled with the applied chemistry of the material so helping to form a durable peripheral seal and bond to aid retention of the restoration as well as arresting the carious process within the remaining tooth structure. Achieving a smooth tooth-restoration interface clinically to aid the cooperative, motivated patient in biofilm removal is an essential pre-requisite to prevent further secondary caries.
Covering: up to February 2014. The methylerythritol 4-phosphate (MEP) pathway is the recently discovered source of isoprenoid precursors isopentenyl diphosphate (IDP) and dimethylallyl diphosphate ...(DMADP) in most bacteria, some eukaryotic parasites, and the plastids of plant cells. The precursors lead to the formation of various isoprenoids having diverse roles in different biological processes. Some isoprenoids have important commercial uses. Isoprene, which is made in surprising abundance by some trees, plays a significant role in atmospheric chemistry. The genetic regulation of this pathway has been discussed but information about metabolic regulation is just now becoming available. This review covers metabolic regulation of the MEP pathway starting from the inputs of carbon, ATP, and reducing power. A number of different regulatory mechanisms involving intermediate metabolites and/or enzymes are discussed. Some recent data indicate that methylerythritol cyclodiphosphate (MEcDP), the fifth intermediate of this pathway, is a key metabolite. It has been found to play diverse roles in regulation within the pathway as well as coordinating other biological processes by acting as a stress regulator in bacteria and possibly a retrograde signal from plastids to the nucleus in plants. In this review we focus on the role of the MEP pathway in photosynthetic leaves during isoprene emission and more generally the metabolic regulation of the MEP pathway in both plants and bacteria.
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•A hierarchical model simulates solid oxide cells and stacks for co-electrolysis.•The model agrees well with electrochemical and thermal measurements from single cells.•Performance ...and cost analysis of cells producing syngas in two output H2:CO ratios.•3-D stack temperature profiles and comparison of cell and stack performance.•Simulation of stack operation under various regimes to evaluate transients.
A hierarchical multi-physics continuum model is used to investigate syngas (H2 + CO) production in a solid oxide button cell, single repeating unit and cell stack. A novel cluster algorithm and pseudo-homogenous approach enables a computationally efficient model scale-up from 1-D button cells to 3-D stacks with minimal loss of information across the scales. The model agrees well with polarization, temperature and outlet gas composition measurements made by Fu et al. on single Ni-GDC|YSZ|LSM-YSZ cells ECS Transactions35, 2949–2956 (2011). After, the model generates 3-D contour plots to map the performance of a single repeating unit of a F-design stack from Forschungszentrum Jülich Fuel Cells7, 204–210 (2007) producing output H2:CO ratios suitable for Fischer-Tropsch synthesis and hydroformylation. Over the range of conditions studied, the overall efficiency and syngas yield increases with residence time though beyond a threshold value, reactant starvation leads to a decrease in efficiency and a greater propensity for Ni coking. Increasing the operating temperature shifts peak efficiencies to lower voltages and the performance of the repeating unit is nearly identical for the two H2:CO ratios studied. On scaling up to produce a commercial quantity of syngas, shorter stacks lead to lower capital costs and smaller electrolyzer areas while running at lower velocities has the opposite effect although it minimizes temperature gradients. Stack simulation over a wide range of operating regimes, including pure H2O and CO2 electrolysis, divulges the time constants of charge, mass and heat transport.
The behaviour of typical armour steel material under large strains, high strain rates and elevated temperatures needs to be investigated to analyse and reliably predict its response to various types ...of dynamic loading like impact. An empirical constitutive relation developed by Johnson and Cook (J–C) is widely used to capture strain rate sensitivity of the metals. A failure model proposed by Johnson and Cook is used to model the damage evolution and predict failure in many engineering materials. In this work, model constants of J–C constitutive relation and damage parameters of J–C failure model for a typical armour steel material have been determined experimentally from four types of uniaxial tensile test. Some modifications in the J–C damage model have been suggested and Finite Element simulation of three different tensile tests on armour steel specimens under dynamic strain rate (10−1s−1), high triaxiality and elevated temperature respectively has been done in ABAQUS platform using the modified J–C failure model as user material sub-routine. The simulation results are validated by the experimental data. Thereafter, a moderately high strain rate event viz. Charpy impact test on armour steel specimen has been simulated using J–C material and failure models with the same material parameters. Reasonable agreement between the simulation and experimental results has been achieved.
This paper explores the feasibility of converting waste Rohu fish (Labeo rohita) scale into a high-performance, reusable, low-cost heterogeneous catalyst for synthesis of biodiesel from soybean oil. ...The thermo-gravimetric analysis (TGA) and X-ray diffraction (XRD) analysis revealed that a significant portion of the main component of fish scale i.e. HAP (hydroxyapatite) could be transformed into β-tri-calcium phosphate when calcined above 900°C for 2h. Scanning Electron Microscopy (SEM) morphology studies of the calcined scale depicted a fibrous layer of porous structure; while a BET surface area of 39m2/g was measured. Response surface methodology (RSM) was employed to determine the optimal parametric conditions viz. methanol/oil molar ratio, 6.27:1, calcination temperature, 997.42°C and catalyst concentration, 1.01wt.% of oil corresponding to a maximum FAME yield of 97.73%. Reusability results confirmed that the prepared catalyst could be reemployed up to six times, procreating a potentially applicable avenue in biodiesel synthesis.
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