Development of combined vector and torque control methods for independent two induction motor drives

Many applications use two or more motors operating in parallel configuration by using one variable speed drive. This system is able to control these multiple motors at the same desired motor speed operation which provide advantages in terms of components and cost reduction. However, the system is not able to control each motor separately if it is desired to operate at different speeds and it also cannot withstand the load disturbance. To address this problem, the design of combined Vector Control-Direct Torque Control (DTC) methods is proposed and their performance is investigated for the case of independent controlled two induction motors fed by single Five Leg Inverter (FLI) method. Double Zero Sequence (DZS) Injection Method Space Vector Pulse Width Modulation (SVPWM) scheme is used for the FLI. Simulation results from the Simulink/Matlab that verify the validity of the method are also included. The results show the ability of the proposed method to control motor speed independently under forward-reverse step speed command and load disturbance condition

Exploring Volunteer Tourism as a Panacea for Sustainable Poverty Alleviation in Nigeria

One of the most intractable menaces that humanity has been battling with several decades ago is poverty. There have been a general consensus about the pervasiveness of poverty and its grave consequences on the well-being of citizens of developing (Nigeria) and least developed nations. Notwithstanding the enormity of human, material and natural resources that nature has endowed in the country which should have been effectively and prudently channeled to alleviate the poverty situation of its citizenry. The said resources have over the years not been properly harnessed and or prudently utilized for societal development. One of the ways to address this cankerworm is economic diversification from crude oil reliance to new areas such as volunteer tourism or voluntourism. This paper examine efforts at poverty alleviation strategies by the government of Nigeria and realized that the efforts has not yielded positive results because the citizenry are still wallowing in abject poverty, inadequate social infrastructure, insecurity, unemployment amongst others as an offspring of poverty. This assertion prompted this study and recommendations among other the utilization of voluntourism that are characterized with financial assistance, knowledge transfer, international connection, integrated national endowment via restoration of environment through skill acquisitions, education, cultural immersion, wealth creation and equitable distribution and economic development. We then recommend that volunteer tourism may be adopted as the main antidote for sustainable poverty alleviation if the opportunity is thoroughly harnesse

Road Vehicle Following System With Adaptive Controller Gain Using Model Reference Adaptive Control Method Lyapunov Approaches

In order to maintain stability and satisfy operating constraints, the control system on the following vehicle needs information about the motion of preceding vehicle. A one-vehicle look-ahead control strategy is proposed and will be investigated for this operation. A mathematical model for this control strategy is obtained and simulated. This paper describes the process of designing an adaptive controller gain for a road vehicle following system using two Lyapunov approach. One approaches utilizes the perfect modelling while the other does not. This is done through simulations and comparisons and is further discussed to find the effectiveness of the two Lyapunov approaches

Identification of Homogeneous Areas for Drought Frequency Analysis

Owing to high spatial and temporal rainfall variability, rationale water management decision-making is complex. Hence, it is essential to identify homogeneous areas to assist water management. This paper focusses on separating the study area into homogeneous groups to predict the risk of occurrence of a drought event. The severity-duration-frequency (SDF) curves were developed to determine the relationship between the probability of a drought occurring with a certain severity and frequency at the selected stations in Victoria, Australia. Two techniques namely cluster analysis and modified Andrews curve were used in grouping study area that have similar climate characteristics with respect to risk of occurrence of drought (i.e. rainfall variability). The study area was divided into six clusters and they adequately covered the study area. A mean drought frequency curve was developed for each homogeneous group to determine the probability of vulnerability to a drought event with a certain severity. The advantage of separating stations into homogenous groups based on similar drought characteristics is that it eliminates the necessity to carry out a detailed drought characteristic analysis for any location of interest. The measurable characteristics of this station will determine its best match with the existing cluster groups

Fabrication of Tm2O3/Al2O3-silica preform by improved MCVD-chelate delivery system

The fabrication of Tm/Al-doped silica preforms by an improved MCVD method with metal chelate precursors is discussed. Two fabrication techniques are employed, namely; simultaneous soot-dopant deposition (or standard MCVD) and stepwise soot-dopant deposition. The preforms are characterized by refractive index profiler and EPMA. The results show that the stepwise soot-dopant technique has a higher incorporation of Al2O3 and Tm2O3 as compared to the simultaneous soot-dopant method. This is due to the drawbacks of our chelate delivery system such as the temperature gradient and flow design. For the stepwise technique, the measured index difference of the preform is 0.006 with 0.8 wt% (maximum) Tm incorporated in the core

Safety and efficacy of human Wharton's Jelly-derived mesenchymal stem cells therapy for retinal degeneration

Purpose To investigate the safety and efficacy of subretinal injection of human Wharton’s Jelly-derived mesenchymal stem cells (hWJ-MSCs) on retinal structure and function in Royal College of Surgeons (RCS) rats. Methods RCS rats were divided into 2 groups: hWJ-MSCs treated group (n = 8) and placebo control group (n = 8). In the treatment group, hWJ-MSCs from healthy donors were injected into the subretinal space in one eye of each rat at day 21. Control group received saline injection of the same volume. Additional 3 animals were injected with nanogold-labelled stem cells for in vivo tracking of cells localisation using a micro-computed tomography (microCT). Retinal function was assessed by electroretinography (ERG) 3 days before the injection and repeated at days 15, 30 and 70 after the injection. Eyes were collected at day 70 for histology, cellular and molecular studies. Results No retinal tumor formation was detected by histology during the study period. MicroCT scans showed that hWJ-MSCs stayed localised in the eye with no systemic migration. Transmission electron microscopy showed that nanogold-labelled cells were located within the subretinal space. Histology showed preservation of the outer nuclear layer (ONL) in the treated group but not in the control group. However, there were no significant differences in the ERG responses between the groups. Confocal microscopy showed evidence of hWJ-MSCs expressing markers for photoreceptor, Müller cells and bipolar cells. Conclusions Subretinal injection of hWJ-MSCs delay the loss of the ONL in RCS rats. hWJ-MSCs appears to be safe and has potential to differentiate into retinal-like cells. The potential of this cell-based therapy for the treatment of retinal dystrophies warrants further studies

Fabrication and characterization of a Gallium co-doped Erbium optical fiber

In this paper, fabrication and characterization of a Gallium co-doped Erbium fiber is presented, highlighting Gallium as a new potential co-dopant to be used in rare-earth doped fibers. This fiber was fabricated using standard MCVD and solution doping method. Fiber characterization setups for fluorescence lifetime, absorption and ASE spectrum are discussed in detail. We go on to show that fluorescence lifetime of 6.02 ms, NA of 0.12, cutoff wavelength of 1.4 μm and a peak absorption of 45 dB/m at 1550 nm is achievable using Gallium as the co-dopant for an Erbium doped fiber

The tourism place-making from a concept of governance

This paper focused on a critical review in tourism place-making from the concept of governance. The term Tourism Place-making is adopted from architecture; planning and design as an approach, and strategies to improve quality of life. However, in tourism, place-making is a process that creates the image of destination. Image destination is very important to attract and to repeat visitation among tourists. At present, tourism destination is controlled and is managed by the government or the top authorities. However, place-making process involves local community and has become a tool to support local economies and it acts as an approach to attract tourism. Thus, the concept of governance has been introduced and it is important for the local society to get involved and to participate in place?making. Moreover, governance has been described as a new form of coordination and coherence among the actors, which is characterized by different objectives and interest. The concept of governance is a different view from government, which involves the society that participates in place?making to create the image of tourism destination. Besides, studying governance provides information to the government on how well their system of governance is able to respond to the changing social, economic, and political circumstances of a society, and also in shaping the decision making process that involves people, values, place, culture, and the philosophy of government. The concept of governance in this study focused on Systems of Governing in destination. Due to these needs, a situational analysis based on literature review in this paper would be able to highlight tourism place?making and the concept of governance for its relevancy in creating an image of tourism destination

Potential approaches on translating expatriates consumption behaviour of spending categories into spatial implication through second homes programmes

Malaysia My Second Home (MM2H) programme is an international residency scheme that allows the expatriates to live in Malaysia on a long stay visa up to 10 years. In the past 10 years, the programme generated about RM17 billion through receipts and spending amounts by the programme's participants. Due to their rights to own properties in the nation, their consumption behavior could spill out to the immediate business areas and gives value-added to surroundings. Thus, this paper aims to highlight the approaches on examining consumption behaviour of MM2H participants. Firstly, this paper reviewed previous researches and methods on analysing consumption behaviour, which later tabulated into spending categories. Afterwards, this paper clarified on chosen methods to translate these categories into spatial mapping, including data collection techniques. Subsequently, the spending categories are vary of 14 distinctive categories. The expenditure pattern is measured by taking into account the spending amount and spending location for each categories. From that, the categories are weighted according to its contribution, and the implication onto spatial locality context are evaluated through weighted spatial mapping analysis. This paper provides methodology on translating consumption behaviour, in relation of understdanding economic impacts at local surrounding context by foreign bodies