Torque Density Improvement Of Spoke Type BLDC Motor Using Hollow Rotor Topology

A spoke type motor has high torque because it uses reluctance torque and magnetic torque simultaneously. Rotor spoke type BLDC have a large amount of circling flux below the permanent magnet. This means that the motor cannot operates in optimum condition due to large unused flux. To overcome this problem, thickness of inner rotor radius, r3 is increase in order to study effect of edge magnet. Hollow rotor is designed to maximize the usage of flux by contributing all the unused flux to circulate around coil. Finite Element Method(FEM) is used to analyze the characteristic and performance of spoke type BLDC machine which include radial flux density, tangential flux density, back emf, inductance, flux linkage and torque. Then, a new spoke type BLDC motor called as Hollow rotor is proposed to overcome the usage of flux in spoke type BLDC motor. For the methodology,some value for design of stator, coil and permanent magnet are selected based on the required specification. After that, electromagnetic characteristic of the selected conventional model is analyzed and parameter for the flux leakage reduction is carried out. In addition, performance analysis of the proposed hollow-rotor also been carried out.Hollow rotor spoke type BLDC motor is been fabricated and experimentally evaluated. The simulation results from the FEM are verified with the measurement result in term of back emf, static torque, torque vs speed, mechanical power, output power, dynamic torque and efficiency and has shown a good agreement. Torque density of hollow-rotor increase almost 50% compared to conventional spoke type BLDC motor. In conclusions, the research proposed a new improvement in spoke type BLDC motor that could provide higher torque density with reasonable motor size. Finally, this thesis provides guidelines, suggestions and proposes a better improved structure in designing BLDC motor

Removal of reactive red 2 dye from aqueous solution by Zn-Al-C03 hydrotalcites / Nor Farina Sulaiman

Hydrotalcites (HTs) were found to have high anionic exchange capacity as removal Reactive Red 2 dye contaminants from aqueous solution. In this study, Z11AICO3-HT was synthesized by using co-precipitation method. Different parameters that affect the adsorption processes were studied which includes effect of contact time at different initial concentration, adsorbent dosage, pH and temperature. The results of contact time at different initial concentration indicate that the maximum percentage uptake of Reactive Red 2 dye by HT is 98.19 % at 6 hours was achieved in 50 ppm. The results of adsorbent dosage indicate that the maximum percentage uptake of Reactive Red 2 dye is 94.36 % was achieved in 0.25 g and for effect of initial pH is 92.97% was achieved at its natural pH, 4.5. Meanwhile for effect of temperature the maximum uptake percentage uptake is 92.97% at 25°C. With increase of contact times, adsorbent dosage, temperature and pH but for pH decreased after achieved its maximum uptake will gave results of increased on adsorption by ZnAlCC^-HT until at point the equilibrium reached. For the effects of initial concentration of dye, the dye adsorption by ZnAlC03-HT decreased as increased at this effects. The results on the adsorption dye fit better into Langmuir isotherm than Freundlich isotherm. The maximum capacity adsorbent of Langmuir is 18.69 mg/g, higher than Freundlich isotherm. The characteristic of these HTs was carried out using FTIR which showed the broad band at 3640 cm"1 due to hydrogen bond, and confirm that the water is present in this HT sample. Other characteristic in these studies also carried out by XRD and FESEM confirmed that the HTs used are true HTs

Performance comparison of spoke and hollow-rotor permanent magnet generator for small energy harvesting application

This paper presents performance comparison between spoke type and hollow-rotor permanent magnet generator (PMG) that could be used for low speed energy harvesting application. In this application, the requirement for such generator would be higher power density due to the limitation of space, volume and weight. The drawback of spoke type PMG is the flux leakage at end of the permanent magnet that embedded inside the rotor. Meanwhile, the hollow-rotor PMG introduces a hollow segment that obstructs the flux from flowing at the end of the permanent magnet. This new arrangement maximizes the energy that contributes by the permanent magnet. The objective of this paper is to compare the performance of both PMG in term of output power and speed at various load condition. In this research finite element analysis is used for modelling and simulating the PMG performance. For final comparison, power density is used for evaluating the best performance and the result shows that the hollow-rotor topology has higher power density compared to spoke type PMG. In the end, this paper provides an overview about the advantage of hollow-rotor topology that could be used for small energy harvesting application

Winding Arrangement Of A New Type Hollow Rotor BLDC Motor

This paper discusses about winding arrangement of fractional slot of a new type hollow rotor Brushless Direct Current (BLDC) motor. Hollow rotor has higher performance compared to other BLDC motor because it minimizes the unused flux below permanent magnet and maximize torque produce by the motor. It’s also known that 8 pole motor is favorite used in industrial because it has an optimum space of permanent magnet for a smaller motor size. The number of pole will affect the maximum speed of the rotor. Thus, the objective of this research is to investigate the best winding arrangement for 8 pole of hollow rotor that could produce the highest electromagnetic performance. At starts, four combinations of slot number and coil sizes had been selected. Structural comparison in term of coil vector and winding arrangement is studied. Finite Element Method (FEM) had been used to simulate the parameters such as backemf and torque waveforms. It was convinced that 9 slot 8 pole with 0.6 size of coil produces the best performance. The confirmed model had been fabricated and measured. Both results from FEM and measurement are compared in term of backemf and torque where percentage differences are 7.4 % and 8 %, respectively. As conclusion, this research shows the fundamental of winding arrangement of fractional slot of motor especially 8 pole motor

Effect of incorporating different concentrations of palm oil as adjuvant in fish vaccine

Adjuvants play important role in vaccine efficacy due to the slow release that leads to prolong immune response. This study determines the advantage of palm oil as adjuvant in the newly developed feed-based killed vaccine against streptococcosis. One thousand two hundred red tilapia of approximately 100g bodyweight were divided into 3 major groups. Group 1 consisted of 500 fish and was further divided into 5 sub-groups with replicate. Group 2 consisted of 600 fish and was further divided into 6 sub-groups while Group 3 with 100 fish in replicate. Fish of Group 1 were vaccinated with the feed-based killed vaccine containing 0%, 3%, 5% and 7% Freund’s incomplete adjuvant (FIA) at weeks 0, 2 and 6. Group 2 was similarly vaccinated with the vaccine containing palm oil adjuvant (POA) at concentrations of 0%, 3%, 5%, 7% & 10%. Group 3 was control without vaccination. On week 10, all fish were challenged intraperitoneally with 2.6 x 109 cfu/ ml of live Streptococcus agalactiae. Serum samples were collected at weekly intervals from all replicates and were subjected to ELISA to determine the systemic antibody responses. Immunization by both POA and FIA resulted in significant (p0.05). The 10% palm oil adjuvant (POA) stimulated the best systemic immune responses resulting in 70% survival rate after challenge

Global patient outcomes after elective surgery: prospective cohort study in 27 low-, middle- and high-income countries.

BACKGROUND: As global initiatives increase patient access to surgical treatments, there remains a need to understand the adverse effects of surgery and define appropriate levels of perioperative care. METHODS: We designed a prospective international 7-day cohort study of outcomes following elective adult inpatient surgery in 27 countries. The primary outcome was in-hospital complications. Secondary outcomes were death following a complication (failure to rescue) and death in hospital. Process measures were admission to critical care immediately after surgery or to treat a complication and duration of hospital stay. A single definition of critical care was used for all countries. RESULTS: A total of 474 hospitals in 19 high-, 7 middle- and 1 low-income country were included in the primary analysis. Data included 44 814 patients with a median hospital stay of 4 (range 2-7) days. A total of 7508 patients (16.8%) developed one or more postoperative complication and 207 died (0.5%). The overall mortality among patients who developed complications was 2.8%. Mortality following complications ranged from 2.4% for pulmonary embolism to 43.9% for cardiac arrest. A total of 4360 (9.7%) patients were admitted to a critical care unit as routine immediately after surgery, of whom 2198 (50.4%) developed a complication, with 105 (2.4%) deaths. A total of 1233 patients (16.4%) were admitted to a critical care unit to treat complications, with 119 (9.7%) deaths. Despite lower baseline risk, outcomes were similar in low- and middle-income compared with high-income countries. CONCLUSIONS: Poor patient outcomes are common after inpatient surgery. Global initiatives to increase access to surgical treatments should also address the need for safe perioperative care. STUDY REGISTRATION: ISRCTN5181700

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p<0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p<0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised

Winding Arrangement of A New Type Hollow Rotor BLDC Motor

This paper discusses about winding arrangement of fractional slot of a new type hollow rotor Brushless Direct Current (BLDC) motor. Hollow rotor has higher performance compared to other BLDC motor because it minimizes the unused flux below permanent magnet and maximize torque produce by the motor. It’s also known that 8 pole motor is favorite used in industrial because it has an optimum space of permanent magnet for a smaller motor size. The number of pole will affect the maximum speed of the rotor. Thus, the objective of this research is to investigate the best winding arrangement for 8 pole of hollow rotor that could produce the highest electromagnetic performance. At starts, four combinations of slot number and coil sizes had been selected. Structural comparison in term of coil vector and winding arrangement is studied. Finite Element Method (FEM) had been used to simulate the parameters such as backemf and torque waveforms. It was convinced that 9 slot 8 pole with 0.6 size of coil produces the best performance. The confirmed model had been fabricated and measured. Both results from FEM and measurement are compared in term of backemf and torque where percentage differences are 7.4 % and 8 %, respectively. As conclusion, this research shows the fundamental of winding arrangement of fractional slot of motor especially 8 pole motor

Nanosecond pulse generation with a gallium nitride saturable absorber

A mode-locked nanosecond Erbium-doped fiber laser (EDFL) was demonstrated using gallium nitrate (GaN) in the form of a polished crystal as a saturable absorber (SA). The GaN film exhibited a modulation depth of 2% with a saturable optical intensity of 0.46 MW/cm2. The laser directly produced nanosecond pulses with stable mode-locking operation at a pump threshold of 149.51 mW. The generated output pulses operated at a 1562 nm central wavelength with a pulse duration and a repetition rate of 485 ns and 967 kHz, respectively. The average output power was 3.068 mW at a pump power of 182.34 mW, corresponding to 3.1 nJ single pulse energy. These results indicate that GaN material has a promising application in ultrafast light generation. © 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Design Of Hollow-Rotor Brushless DC Motor

This paper discusses about design of hollow-rotor Brushless DC (BLDC) motor. A conventional BLDC motor has more leakage flux circling at the end of the permanent magnet that will limit torque. To overcome this problem, a new BLDC model known as hollow-rotor is proposed. The objective of this research is to design a hollow-rotor motor that will have higher torque density compared to conventional BLDC motor using Finite Element Method (FEM). In addition, performance analysis of the proposed hollow-rotor has also been carried out. For validation, the result of FEM is compared with the measurement result. It shows that, the simulation result has good agreement with the measurement result. For comparison, hollow-rotor shows higher torque density compared to conventional BLDC motor. As a conclusion, this paper provides guidelines and analysis in designing high torque hollow-rotor motor