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Hanuman Prasad and Tanmoy Maity

Abstract

This paper presents the small signal modeling using the state space averaging technique and reliability analysis of a three-phase z-source ac-ac converter. By controlling the shoot-through duty ratio, it can operate in buck-boost mode and maintain desired output voltage during voltage sag and surge condition. It has faster dynamic response and higher efficiency as compared to the traditional voltage regulator. Small signal analysis derives different control transfer functions and this leads to design a suitable controller for a closed loop system during supply voltage variation. The closed loop system of the converter with a PID controller eliminates the transients in output voltage and provides steady state regulated output. The proposed model designed in the RT-LAB and executed in a field programming gate array (FPGA)-based real-time digital simulator at a fixedtime step of 10 μs and a constant switching frequency of 10 kHz. The simulator was developed using very high speed integrated circuit hardware description language (VHDL), making it versatile and moveable. Hardware-in-the-loop (HIL) simulation results are presented to justify the MATLAB simulation results during supply voltage variation of the three phase z-source ac-ac converter. The reliability analysis has been applied to the converter to find out the failure rate of its different components.

Open access

Prajapati Hanuman Prasad, Singh Deepak Kumar, Singh Rakesh Kumar and Ahmad Faran

Abstract

Intramedullary pyogenic abscess in the conus medullaris in a young child is an extremely rare condition. It had never been reported in literature. It should be differentiated from other more common pathology like tubercular abscess, dermal sinus, epidermoid and dermoid tumour. Early diagnosis and prompt surgical evacuation may lead to good neurological recovery from this rare benign pathology.

Open access

Prajapati Hanuman Prasad, Singh Deepak Kumar, Singh Rakesh Kumar and Yadav Kuldeep

Abstract

In small childrens spine injuries are rare. In this age group upper cervical spine is commonally affected. Odontoid process fracture involve only a subset of cervical spine fractures. In small childrens, this fracture typically involves the cartilaginousplate that separates the odontoid process from the body of the axis. Odontoid processfracture is rare in children less than 7 years of age.

Open access

Prajapati Hanuman Prasad, Singh Deepak Kumar, Singh Rakesh Kumar and Ahmed Faran

Abstract

Lumbar disc herniation is a common disease that present with back pain and radicular pain. The most efficient method for the treatment of lumbar disc herniation is still controversial. Spontaneous regression of lumbar disc herniation has been recognized with the advancement of radiological diagnostic tools and can explain the reason of spontaneous relief of symptoms without treatment. The proposed hypothesis are; dehydration, retraction of the disc herniation in the annulus fibrosus, enzymatic catabolism and phagocytosis. In this study we present a case with large lumbar disc herniation regressing by itself and the potential mechanisms of disc regression have been discussed.

Open access

Faran Ahmad, Deepak Kumar Singh, Hanuman Prasad Prajapati and Anuj Chhabra

Abstract

Cirsoid aneurysms (arteriovenous malformations [AVMs]) are Anomalous fistulous arteriovenous communications of scalp with ill-defined natural course that are rarely encountered in neurosurgery. Patients with AVM of the scalp present clinically with headache and either a small innocuous-looking subcutaneous scalp lump or a large, pulsatile mass with or without bruit, which has a propensity to massive hemorrhage. Complex vascular anatomy and interconnections and high shunt flow make their management difficult. We report a rare case of a 40-year-old man who presented with a swelling over his occipital region that progressively enlarged over the course of 6 years. Being high flow shunt surgical excision was attempted.

Open access

Prajapati Hanuman Prasad, Singh Deepak Kumar, Singh Rakesh Kumar, Ahmad Faran and Chhabra Anuj

Abstract

Sinonasal undifferentiated carcinoma (SNUC) is an aggressive malignancy originating in the mucosa lining the walls of the nasal cavity and paranasal sinuses. It is a rare tumor that usually presents in an advanced stage, is highly invasive, and is traditionally reputed to be refractory to even the most radical therapy with an attendant poor prognosis. This is particularly true when it transgresses the cranial base.

Open access

Prajapati Hanuman Prasad, Singh Deepak Kumar, Singh Rakesh Kumar, Ahmed Faran and Chhabra Anuj

Abstract

Ventriculoperitoneal (VP) shunt, a common neurosurgical procedure, has a long list of known complications associated with it. A rare but dangerous complication of VP shunt procedure is extradural hematoma (EDH). It can be diagnosed and managed easily before it turns into a catastrophic complication.