On the Prediction of Grain Refinement Mechanism in Direct Chill Casting of Aluminum and Its Alloys Under Low Degree Mechanical Forced Convection

Deepak Patel,Prasenjit Biswas,Anil Kumar,Hiren R. Kotadia,Archana Mallik,Sanjeev Das 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.7

The present investigation focuses on grain refinement in pure aluminum and its alloy under mechanical stirring with a verylow degree of forced convection of 800 rpm as compared to reported values of up to 8000 rpm during direct chill castingprocess (DC). Commercially pure aluminum (99.7%) and Al6082 alloy billets were fabricated in an in-house designed DCcasting simulator. Mechanical forced convection (MFC) was applied to the melt during casting by a common four-bladedimpeller. The microstructural properties of the as-cast billets have been analysed to study the effect of MFC during casting andsolidification. The structure of both Al and its alloy is found to be refined in presence of MFC as compared to conventionalDC. A combination of simulation, experimental and theoretical approaches has been used to determine the effect of MFCin melt-temperature distribution to propose the mechanism of grain refinement. It has been observed that MFC prominentlyreduces the temperature gradient and extends undercooling time, resulting in fine grain structure.

Adaptive smith predictor controller for total intravenous anesthesia automation

Bhavina Patel,Hiren Patel,Pragna Vachhrajani,Divyang Shah,Alpesh Sarvaia 대한의용생체공학회 2019 Biomedical Engineering Letters (BMEL) Vol.9 No.1

Anesthetic agent propofol needs to be administered at an appropriate rate to prevent hypotension and postoperative adversereactions. To comprehend more suitable anesthetic drug rate during surgery is a crucial aspect. The main objective of thisproposal is to design robust automated control system that work effi ciently in most of the patients with smooth BIS andminimum variations of propofol during surgery to avoid adverse post reactions and instability of anesthetic parameters. And also, to design advanced computer control system that improves the health of patient with short recovery time and lessclinical expenditures. Unlike existing research work, this system administrates propofol as a hypnotic drug to regulate BIS,with fast bolus infusion in induction phase and slow continuous infusion in maintenance phase of anesthesia. The novelty ofthe paper lies in possibility to simplify the drug sensitivity-based adaption with infusion delay approach to achieve closedloopcontrol of hypnosis during surgery. Proposed work uses a brain concentration as a feedback signal in place of the BISsignal. Regression model based estimated sensitivity parameters are used for adaption to avoid BIS signal based frequentadaption procedure and large off set error. Adaptive smith predictor with lead–lag fi lter approach is applied on 22 diff erentpatients’ model identifi ed by actual clinical data. The actual BIS and propofol infusion signals recorded during clinical trialswere used to estimate patient’s sensitivity parameters EC 50 and λ . Simulation results indicate that patient’s drug sensitivityparameters based adaptive strategy facilitates optimal controller performance in most of the patients. Results are obtainedwith proposed scheme having less settling time, BIS oscillations and small off set error leads to adequate depth of anesthesia. A comparison with manual control mode and previously reported system shows that proposed system achieves reductionin the total variations of the propofol dose. Proposed adaptive scheme provides better performance with less oscillation inspite of computation delay, surgical stimulations and patient variability. Proposed scheme also provides improvement inrobustness and may be suitable for clinical practices.

Psychiatric Comorbidities in Adults with DiGeorge Syndrome

Hiren Patel,Ramu Vadukapuram,Zeeshan Mansuri,Chintan Trivedi,Kanwarjeet Singh Brar,Uzma Beg,Jigar Patel,Aalamgeer Ibrahim,Muhammad Khalid Zafar 대한정신약물학회 2022 CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE Vol.20 No.3

Objective: DiGeorge Syndrome (DGS) is a common multisystem disorder associated with deletions on chromosome 22q11.2. Our objective is to evaluate the psychiatric comorbidities and demographics of patients suffering from DGS in a nationally representative dataset on inpatient hospitalizations. Methods: The Nationwide Inpatient Sample for the year 2005−2017 was used for this study. Data on patients with DiGeorge syndrome were collected by using the International Classification of Diseases code. Univariate and multivariate logistic regression analysis was performed. Results: In our study, the average age was 30.4 years (n = 6,563), with 59.9% male, and 61.8% of patients were white. There was a high prevalence of mood disorders (24.7%) and anxiety disorders (16.4%), followed by schizophrenia and other psychotic condition (14.0%). In patients with mood disorders, 8% had Major Depressive Disorder, and 7% had bipolar depression. Overall composite of psychiatric comorbidities was present in 2,959 (45.1%) of patients. The mean length of stay was 6.58 days, and 77% of patients had routine discharge to home. In the adjusted analysis, the average length of stay was 8.6 days vs. 6.7 days (p < 0.001) in patients with and without psychiatry comorbidities. In comparison to routine discharge, patients with psychiatry comorbidities were more likely to be discharged to other healthcare facilities (odds ratio [OR]: 1.28, p < 0.001) and discharged against medical advice (OR: 3.45, p < 0.001). Conclusion: Patients with DGS have worse outcomes with a higher rate of discharge to other healthcare facilities and a higher rate of being discharged against medical advice. Further large scale randomize studies are indicated.

Modified droop control scheme for load sharing amongst inverters in a micro grid

Patel, Urvi N.,Gondalia, Dipakkumar,Patel, Hiren H. Techno-Press 2015 Advances in energy research Vol.3 No.2

Microgrid, which can be considered as an integration of various dispersed resources (DRs), is characterized by number of DRs interfaced through the power electronics converters. The microgrid comprising these DRs is often operated in an islanded mode. To minimize the cost, reduce complexity and increase reliability, it is preferred to avoid any communication channel between them. Consequently, the droop control method is traditionally adopted to distribute active and reactive power among the DRs operating in parallel. However, the accuracy of distribution of active and reactive power among the DRs controlled by the conventional droop control approach is highly dependent on the value of line impedance, R/X i.e., resistance to reactance ratio of the line, voltage setting of inverters etc. The limitations of the conventional droop control approach are demonstrated and a modified droop control approach to reduce the effect of impedance mis-match and improve the time response is proposed. The error in reactive power sharing is minimized by inserting virtual impedance in line with the inverters to remove the mis-match in impedance. The improved time response is achieved by modifying the real-power frequency droop using arctan function. Simulations results are presented to validate the effectiveness of the control approach.

AgriOnBlock: Secured Data Harvesting for Agriculture Sector using Blockchain Technology

Hiren Patel,Bela Shrimali 한국통신학회 2023 ICT Express Vol.9 No.2

The existing agriculture system is having several components such as supply chain management, crop insurance, the shipment of goods, and it involves numerous untrusted stakeholders such as users (farmers, retailers, customers, wholesalers, etc.), agencies (bank, insurance company) and regulators (assessor, surveyors). Due to the active engrossment of the middle man (mostly human beings or agencies operated by human beings) some key issues are raised such as transparency, timeliness, traceability, security, and immutability resulting in financial loss, crop contamination, and spoilage. Secure distributed public ledger technology and decentralized computing paradigm make Blockchain an appropriate alternative to resolve these issues and to achieve profitability & trust for all its stakeholders. In this research, we intend to propose a Blockchain-based mechanism viz. AgriOnBlock which would address the issues mentioned in the agriculture sector by connecting various stakeholders through the usage of IoT devices and smart contracts in Ethereum. We further discuss implications, constraints (methodological, awareness related, regulatory, etc.), and potential for actual adoption of AgriOnBlock.

Anomalous Origin of the Left Coronary Artery from the Pulmonary Artery in Adulthood: Challenges and Outcomes

Jignesh Kothari,Ketav Lakhia,Parth Solanki,Divyakant Parmar,Hiren Boraniya,Sanjay Patel 대한흉부외과학회 2016 Journal of Chest Surgery (J Chest Surg) Vol.49 No.5

Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) is an extremely rare, potentially fatal, congenital anomaly with a high mortality rate in the first year of life. It occurs rarely in ad ulthood and may a ppear with m alignant v entricular a rrhythmia or s ud d e n d eath. W e report a c ase of a 49-year-old woman with ALCAPA who presented with dyspnea on exertion. Management was coronary artery bypass grafting to the left anterior descending artery and obtuse marginal arteries, closure of the left main coronary artery ostium, and reestablishment of the dual coronary artery system.