Investigation of self switching flux pump for high temperature superconducting magnets

The rapid development of second-generation (2G) high-temperature superconducting (HTS) coated conductors (CCs) has made it possible to manufacture 2G HTS coils with enormous potential for a wide range of applications, including magnetic resonance imaging (MRI) magnets, electrical propulsion systems (HTS machines), magnetic levitation trains, and energy storage (SMES). While these coils can be operated using either DC or AC current, challenges such as properly magnetizing an HTS coil under DC conditions and reducing losses under AC conditions still need to be addressed before their widespread use in scientific and industrial settings. Typically, high-current power supplies power these coils through current leads, which can complicate insulation between cryogenic and room temperature environments. Fortunately, HTS flux pumps provide an alternative method of energizing superconducting magnets without the need for direct electrical contacts, reducing resistive heating and heat leakage from current leads at room temperature. Recent developments in flux pumps for HTS magnets have made it possible to charge kA levels of current without the need for thick current leads. This thesis aims to provide a comprehensive investigation of charging an HTS magnet to operate it in a persistent current mode, and presents a novel perspective on controlling the magnetic field in HTS magnets via flux pumping. First a two-dimensional (2D) model of a single turn high-temperature superconducting (HTS) coil was developed using a well-established H-formulation, which was iteratively refined to eliminate numerical errors from the solution. The resulting model provides insights into the self-rectifying flux pumping mechanism, which was subsequently validated experimentally. The 2D model also enables the estimation of the over-critical current voltage (also known as the flux flow voltage) across the HTS tape, which acts as a stable voltage source for injecting current into the HTS magnet. This results in the quantization of the bridge voltage, enabling precise flux injection into a fully superconducting circuit. A higher stable dc voltage can be achieved across the terminals of the HTS magnet using a bifilar coil as a bridge (bridge – the HTS tape short-circuits the terminals of the magnet and the secondary coil), the results are verified experimentally. The influence of the HTS tape and bifilar coil acting as a bridge across the HTS magnet is investigated. The results show that the bifilar bridge gives higher stable dc voltage to charge the HTS magnet to its critical current values and leads to the compact geometry making it suitable for adoption to complex geometries like rotor magnets in HTS machines. HTS flux pumps can charge the magnet and compensate for any current decay, enabling quasi-persistent operation of HTS magnets. To operate an HTS magnet in the persistent current mode, a jointless HTS magnet is constructed that offers zero joint resistance, allowing it to operate in persistent current mode. However, when used in applications like rotors of fully superconducting machines, it continuously experiences a background magnetic field in the form of magnetomotive force coming from the stator. The external alternating field can cause a gradual decay of the magnetic field. Therefore, this work presents a closed-loop feedback control for field modulation in HTS magnets to operate in persistent current mode. This method eliminates the need for continuous flux pumping and allows for the injection and reduction of current in increments of 0.5 A. This flux modulation can enable a stable magnetic field for HTS magnets. Finally, the thesis investigates critical aspects of the flux pumping in HTS magnets operating at 30 K, marking an advancement in the field of HTS magnet technology as previous flux pumps have only been reported to operate at higher temperatures. These results provide insight into achieving a stable magnetic field in HTS magnets via flux pumping and outline the methods to compensate for current decay in HTS magnets operating in the persistent current mode – opening new pathways to high-field, low-cost HTS magnets.The rapid development of second-generation (2G) high-temperature superconducting (HTS) coated conductors (CCs) has made it possible to manufacture 2G HTS coils with enormous potential for a wide range of applications, including magnetic resonance imaging (MRI) magnets, electrical propulsion systems (HTS machines), magnetic levitation trains, and energy storage (SMES). While these coils can be operated using either DC or AC current, challenges such as properly magnetizing an HTS coil under DC conditions and reducing losses under AC conditions still need to be addressed before their widespread use in scientific and industrial settings. Typically, high-current power supplies power these coils through current leads, which can complicate insulation between cryogenic and room temperature environments. Fortunately, HTS flux pumps provide an alternative method of energizing superconducting magnets without the need for direct electrical contacts, reducing resistive heating and heat leakage from current leads at room temperature. Recent developments in flux pumps for HTS magnets have made it possible to charge kA levels of current without the need for thick current leads. This thesis aims to provide a comprehensive investigation of charging an HTS magnet to operate it in a persistent current mode, and presents a novel perspective on controlling the magnetic field in HTS magnets via flux pumping. First a two-dimensional (2D) model of a single turn high-temperature superconducting (HTS) coil was developed using a well-established H-formulation, which was iteratively refined to eliminate numerical errors from the solution. The resulting model provides insights into the self-rectifying flux pumping mechanism, which was subsequently validated experimentally. The 2D model also enables the estimation of the over-critical current voltage (also known as the flux flow voltage) across the HTS tape, which acts as a stable voltage source for injecting current into the HTS magnet. This results in the quantization of the bridge voltage, enabling precise flux injection into a fully superconducting circuit. A higher stable dc voltage can be achieved across the terminals of the HTS magnet using a bifilar coil as a bridge (bridge – the HTS tape short-circuits the terminals of the magnet and the secondary coil), the results are verified experimentally. The influence of the HTS tape and bifilar coil acting as a bridge across the HTS magnet is investigated. The results show that the bifilar bridge gives higher stable dc voltage to charge the HTS magnet to its critical current values and leads to the compact geometry making it suitable for adoption to complex geometries like rotor magnets in HTS machines. HTS flux pumps can charge the magnet and compensate for any current decay, enabling quasi-persistent operation of HTS magnets. To operate an HTS magnet in the persistent current mode, a jointless HTS magnet is constructed that offers zero joint resistance, allowing it to operate in persistent current mode. However, when used in applications like rotors of fully superconducting machines, it continuously experiences a background magnetic field in the form of magnetomotive force coming from the stator. The external alternating field can cause a gradual decay of the magnetic field. Therefore, this work presents a closed-loop feedback control for field modulation in HTS magnets to operate in persistent current mode. This method eliminates the need for continuous flux pumping and allows for the injection and reduction of current in increments of 0.5 A. This flux modulation can enable a stable magnetic field for HTS magnets. Finally, the thesis investigates critical aspects of the flux pumping in HTS magnets operating at 30 K, marking an advancement in the field of HTS magnet technology as previous flux pumps have only been reported to operate at higher temperatures. These results provide insight into achieving a stable magnetic field in HTS magnets via flux pumping and outline the methods to compensate for current decay in HTS magnets operating in the persistent current mode – opening new pathways to high-field, low-cost HTS magnets

Feedback-controlled flux modulation for high-temperature superconducting magnets in persistent current mode

High-temperature superconducting (HTS) magnets have found wide applications in high-field settings owing to their high current capabilities. Typically, these magnets are powered by high-current power supplies via current leads, which can complicate insulation between cryogenic and room temperature environments. However, new developments in flux pumps for HTS magnets have enabled charging of kA levels of current without power supplies. By combining flux pumps with HTS persistent current operation, it is possible to achieve accurate flux modulation and eliminate the need for power supplies and current leads. In this study, we report on a novel feedback-controlled flux modulation for HTS magnets in persistent current operations. This flux modulation is based on a flux pump mechanism that generates a DC voltage across the charging superconductor by applying a current higher than its critical current. With closed-loop feedback control, our flux modulation can achieve precise injection and reduction of HTS magnet current in increments of 0.5 A. This technology can lead to stable magnetic fields in HTS magnet designs. We anticipate that this work will enable future magnets to operate in a stable persistent current mode within a closed cryogenic chamber, significantly reducing the footprint and power demand of HTS magnets and opening up new opportunities for their applications

A non-inductive bifilar coil to design compact flux pumps for HTS magnets

High temperature superconducting flux pump is a promising way of energizing superconducting magnets without direct electrical contacts. It can remove the resistive heating and heat leakage from the current leads at room temperature. It is well known that applying the current over the critical current of the superconductor, will force the superconducting layer to enter into the flux flow regime. This flux flow resistivity generates a dc voltage across the length of the HTS tape. This phenomenon is well understood, however, it is difficult to generate a high dc charging voltage without a high current. In this work, we demonstrate a novel flux pumping technique by using a non-inductive bifilar bridge wound in parallel to the HTS coil. This configuration can generate large dc voltages using relatively small currents. It results in effectively pumping dc currents equal to the critical current for large HTS magnets

Pharmacological evaluation of Vernonia elaeagnifolia (Asteraceae) leaves in hyperlipidemic albino rabbits

Purpose: To evaluate the antihyperlipidemic efficacy and phytochemical constituents of Vernonia elaeagnifolia aqueous leaf extract.Method: Qualitative phytochemical analysis of V. elaeagnifolia leaves was performed. Thirty healthy albino rabbits were divided into six groups (n = 6). Cholesterol powder (0.5 g/kg) in 10 mL coconut oil (vehicle) was given orally to induce hyperlipidemia. The aqueous leaf extract of Vernonia elaeagnifolia was administered at 250 mg/kg and 500 mg/kg per oral. Lipid profile, hepatic enzymes and oxidative stress markers were evaluated.Results: Phytochemical screening indicated the presence of tannins, proteins, flavonoids, phenols, alkaloids and saponins. Oral administration of cholesterol powder significantly (p < 0.05) raised the level of serum total cholesterol (TC), low-density lipoprotein cholesterol (LDL-c) and triglyceride (TG) along with significant (p < 0.05) decrease in serum concentration of high-density lipoprotein cholesterol (HDLc). Concentration of serum TC, LDL-c, TG and liver enzymes was significantly reduced in V. elaeagnifolia-treated groups. The levels of oxidative stress markers were restored to normal when the animals were treated with V. elaeagnifolia leaf extract; increased levels of antioxidant enzymes were observed.Conclusion: The aqueous leaf extract of V. elaeagnifolia possesses antihyperlipidemic and antioxidant potentials that are dose-dependent. However, further studies are required to develop the plant for therapeutic applications.Keywords: Hyperlipidemia, Oxidative stress markers, Cholesterol, Vernonia elaeagnifoli

TO DETERMINE THE INCIDENCE OF DIABETIC NEPHROPATHY AMONG DIABETIC PATIENTS ATTENDING THE MEDICINE DEPARTMENT OF ALLIED HOSPITAL FAISALABAD

Aim: To assess the incidence of diabetic nephropathy in patients attending the Allied Hospital Faisalabad. Material: This prospective cross-sectional study has been conducted at the Allied Hospital Faisalabad for one year duration from April 2019 to April 2020. One hundred patients with type 2 diabetes with a duration of diabetes below five years and age 30, 70 years were selected. Urine complete examination and urinary albumin to creatinine ratio was seen in the first void urine. Results: In 20% of a hundred patients, urinary albumin index was 30 mg / g and diabetic nephropathy was diagnosed. There was no evidence of diabetic nephropathy in 70% of patients. Conclusion: Diabetic patients have a high percentage of diabetic nephropathy in the study. Key words: diabetic nephropathy, Urinary albumin creatinine ratio

Performance optimization of pillow sheet set sewing assembly line by SAM analysis and lean manufacturing techniques of method study & work measurement

[EN] This research was conducted to enhance the productivity of the targeted sewing line at the ABC textile company. The existing SAMs, the capacity of the sewing line for various operations, and several required machines were collected. Moreover, the obtained figures were observed and analyzed by using time study and motion study, and certain improvements were made at the sewing line. Results indicated that SAMs for operations A and B were minimized by -13.64% and -14.54% respectively; whereas, SAM for operation C was increased by 16.67%. Machine requirement for operation C was increased by 100%; moreover, the capacity for operations A, B, and C was increased by 12%, 12.69%, and 40% respectively. When it is to production activities, the little improvements play a significant role in boosting the productivity of the production system. Optimal allocation of human resources, machines, and time are the benefits of line balancing. This can be made possible with the application of the line-balancing framework. With every passing day, the nature and type of article vary at the sewing line thus it is highly needed for the company to get the model developed for an automated line balancing application. Moreover, this work can be extended by the development of a line-balancing framework considering the nature of production.Haseeb, A.; Khan, MA.; Shaikh, SA.; Iftikhar, Z.; Kumar, R.; Bux, K.; Naz, A.... (2023). Performance optimization of pillow sheet set sewing assembly line by SAM analysis and lean manufacturing techniques of method study & work measurement. Journal of Applied Research in Technology & Engineering. 4(1):1-12. https://doi.org/10.4995/jarte.2023.178611124

Potential Therapeutic Benefits of Honey in Neurological Disorders: The Role of Polyphenols

Honey is the principal premier product of beekeeping familiar to Homo for centuries. In every geological era and culture, evidence can be traced to the potential usefulness of honey in several ailments. With the advent of recent scientific approaches, honey has been proclaimed as a potent complementary and alternative medicine for the management and treatment of several maladies including various neurological disorders such as Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, and multiple sclerosis, etc. In the literature archive, oxidative stress and the deprivation of antioxidants are believed to be the paramount cause of many of these neuropathies. Since different types of honey are abundant with certain antioxidants, primarily in the form of diverse polyphenols, honey is undoubtedly a strong pharmaceutic candidate against multiple neurological diseases. In this review, we have indexed and comprehended the involved mechanisms of various constituent polyphenols including different phenolic acids, flavonoids, and other phytochemicals that manifest multiple antioxidant effects in various neurological disorders. All these mechanistic interpretations of the nutritious components of honey explain and justify the potential recommendation of sweet nectar in ameliorating the burden of neurological disorders that have significantly increased across the world in the last few decades

A Comprehensive review of functional ingredients, especially bioactive compounds present in pumpkin peel, flesh and seeds, and their health benefits

Pumpkin (Cucurbita maxima), belonging to family Cucurbitaceae, is a well-known edible plant, cultivated and abundantly used as herbal medicine and functional food. This review aimed to investigate functional and nutraceutical constituents present in all three parts (peel, flesh and seeds) of pumpkin, and health benefits of these nutrients. Pumpkin fractions are rich source of nutritional components like oils, proteins, carbohydrates and minerals. Certain classes of phytochemical compounds including, phenolics, flavonoids, tocopherols, carotenoids, terpenoids, cucurbitacin, moschatin and phytosterols have been discovered from pumpkin fractions. Considerable evidences from several epidemiological studies upon animals and human trials have been present about pharmacological actions of pumpkin bio actives. Therapeutically, pumpkin peel, flesh and seeds contain active ingredients, acting as effective antioxidants and antimicrobial agents. No part of pumpkin fruit should be discarded during processing as these parts possess excellent phytochemistry, capable of impacting positive health impacts. All these parts of pumpkin can be used in the form of powders or extracts to isolate and characterize bio-actives and to utilize them in food and pharmaceutical industries as therapeutic agents. Instead of consumption in raw form, technologies should be implemented to develop novel and innovative nutraceuticals and pharma foods from health beneficial constituents of pumpkin