Mining Frequent Sequential Patterns From Multiple Databases Using Transaction Ids

Mining frequent sequential patterns from multiple databases to discover more complex patterns from multiple data sources such as multiple E-Commerce (B2C) web sites for comparative, historical and derived analysis, poses the additional challenge of integrating mined patterns from multiple sources during various levels of mining. A few existing work on mining frequent patterns from multiple databases (MDB’s) are the ApproxMap algorithm and the TidFP algorithm. The ApproxMap algorithm breaks its input sequences (e.g., the 2-column sequence \u3c(123)(45)\u3e) into columns so it can find the collection of approximate frequent sequences of all the columns as the approximate sequence of the database. The same method is used to integrate frequent sequences from each MDB that must have the same table structure. The TidFP algorithm mines frequent item_sets from multiple sources of different table structures and related through foreign key attributes using transaction ids for integrating patterns through set operations (e.g., intersect, union) in order to answer global queries involving multiple sources. The limitations of existing work on multiple database sequential pattern mining such as the ApproxMap algorithm is that they are not able to mine frequent sequences to answer exact and historical queries from MDB’s of different structure; while the TidFp algorithm can only answer queries from MDB’s on item_sets but not for sequences. This thesis proposes the Transaction id frequent sequence pattern (TidFSeq) algorithm which uses the techniques of the TidFP algorithm for mining item sets on the problem of mining frequent sequences from diverse MDB’s. The challenges with mining frequent sequences from MDBs that is solved by this thesis are that the TidFSeq algorithm first computes the element (ie. Sequence item position id) in which each item in each sequence (ie. sequence id) occurs by replacing the tuple used in the TidFp with a tuple. For every item ‘i’ in the kth sequence of n-sequence of length ‘n’, the TidFSeq algorithm first transforms it into a tuple that specifies (a) it’s transaction id (Tid) and (b) the list of the kth sequence in this transaction that item ‘i’ occurs (called it’s position id list). Next the GSP-like candidate generation approach is used on our transformed sequences to generate frequent sequences with transacion ids which can be used to answer complex queries from MDB’s through set operations. The proposed TidFSeq algorithm, PrefixSpan algorithm and ApproxMap algorithm are compared with respect to the results obtained for a given query, processing speed and memory requirement. Experiments show that the proposed TidFSeq algorithm mines the exact frequent sequences (ie. 100% accuracy) from multiple sequence tables, when compared to the ApproxMap algorithm that has an accuracy of 79%. The TidFSeq algorithm has faster processing time for mining frequent sequences from multiple tables than the PrefixSpan and ApproxMap algorithms

Mining Integrated Sequential Patterns From Multiple Databases

Existing work on multiple databases (MDBs) sequential pattern mining cannot mine frequent sequences to answer exact and historical queries from MDBs having different table structures. This article proposes the transaction id frequent sequence pattern (TidFSeq) algorithm to handle the difficult problem of mining frequent sequences from diverse MDBs. The TidFSeq algorithm transforms candidate 1-sequences to get transaction subsequences where candidate 1-sequences occurred as (1-sequence, itssubsequenceidlist) tuple or (1-sequence, position id list). Subsequent frequent i-sequences are computed using the counts of the sequence ids in each candidate i-sequence position id list tuples. An extended version of the general sequential pattern (GSP)-like candidate generates and a frequency count approach is used for computing supports of itemset (I-step) and separate (S-step) sequences without repeated database scans but with transaction ids. Generated patterns answer complex queries from MDBs. The TidFSeq algorithm has a faster processing time than existing algorithms

Performance Analysis of Different Current Control strategies for Grid Tied Three Phase Voltage Source Inverter

This paper deals with the comparative performance analysis of different current control strategies  for grid connected three phase voltage source inverters (VSI). The different strategies considered were conventional Hysteresis current controller, Ramp comparison controller and User Defined Constant Switching frequency (UDCS) controller. Limitations and advantages of each control strategy have been discussed. The different control strategies have been simulated using Matlab Simulink 8.1. Based on the simulation results comparative performance analysis has been carried out in terms of Dynamic response, Reference tracking capability and Total Harmonic Distortion (THD). Phase Plane Trajectory of different strategies has been simulated in order to validate the performance of each control strategy under non-linear disturbance conditions.      

Design and Optimization of Spur Gear Box Parameters

The field of gear design is an extremely broad and complex area, and a complete coverage in any research work is not possible. In this work only parallel axis spur gear reduction unit which is the type, probably encountered most often in general practice, has been considered. A review of relevant literature in the areas of optimized design of spur gear indicates that compact design of spur gears involves a complicated algebraic analysis. A series of iterations is normally required to arrive at a practical combination of pinion teeth and module from their theoretical values. The present work describes the development of such a design methodology and diagnostic tool for determining the modes of failures for spur gear and also the causes of these failures have been studied. The ray diagram is also considered for finding out the minimum diameter and maximum transmission range. The focus is on developing a design space which is based on module and pinion teeth by using a simple logical statement in computer software. This is a much simplified approach for obtaining practical values of the module and pinion teeth for an optimum minimum centre distance between the two transmission shafts. Attention has been devoted to determine the exact mode of failure which dictated the design at the optimum conditions corresponding to the minimum centre distance for the design of gear reduction unit minimum dimensions

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Cu-doped P2-Na0.5Ni0.33Mn0.67O2 encapsulated with MgO as a novel high voltage cathode with enhanced Na-storage properties

We report a novel P2-type Na0.5Ni0.26Cu0.07Mn0.67O2 (NCM) mixed oxide obtained by conventional solid-state method as a prospective cathode for sodium-ion battery (SIB) applications. X-ray diffraction analysis shows that NCM exhibits a hexagonal structure with a P6(3)/mmc(No. 194) space group, in which Na-ions are located in a prismatic environment. The introduction of Cu into the lattice enhances its structural stability, showing a capacity retention of 83% after 100 cycles, which is much better than its native compound. MgO encapsulation was performed to further improve the interfacial kinetics and suppress P2-O2 phase transition. MgO coating significantly improves the electrochemical activity at high cut-off voltages, for instance, highest capacity of 131 mA h g(-1) was noted with superior rate performance of 83 and 51 mA h g(-1) at 5 and 20C, respectively. As expected, dual modification by Cu-ion doping and MgO coating provides a novel strategy for designing high-rate SIB cathodes.