Snack food packaging features and consumer repeat purchase intent

The visual aspects of snack food packaging can influence repeat purchase intention. In today’s busy working lifestyle, snack food may replace one or more of the daily meals. Previous studies reported the inconsistent finding of characteristics of packaging with consumer repeat purchase intent. Thus, this study has been conducted to investigate the relationship between the characteristics of visual and verbal packaging for snacks with consumer repeat purchase intent. The study was conducted at a big supermarket located in the Johore State, Malaysia. The convenient purposive sampling was used to select the consumers who went shopping at the selected supermarket. A total of 217 survey questionnaires were distributed to collect the needed data. Data were analyzed descriptively, the central tendency (skewness), and regression. Overall, the outcome of this research shows the visual features of the snack food packaging is significantly related to consumer repeat purchase intent at p < 0.001. On the other hand, it was found that there is no association between the verbal packaging features with repeat purchase intent. This indicates that visual features are crucial to consumers in their snack food product selection. It is also possible that snacks (junk food) consumers may not be concerned with nutritional value. This could be in the context that such products are of lower involvement, where not much further information is needed. However, recommended that it needs further research in this case. In conclusion, manufacturers can focus on the visual packaging features of snack food product to attract their customers to buy their packed snack food product

Power Converter of Electric Machines, Renewable Energy Systems, and Transportation

Power converters and electric machines represent essential components in all fields of electrical engineering. In fact, we are heading towards a future where energy will be more and more electrical: electrical vehicles, electrical motors, renewables, storage systems are now widespread. The ongoing energy transition poses new challenges for interfacing and integrating different power systems. The constraints of space, weight, reliability, performance, and autonomy for the electric system have increased the attention of scientific research in order to find more and more appropriate technological solutions. In this context, power converters and electric machines assume a key role in enabling higher performance of electrical power conversion. Consequently, the design and control of power converters and electric machines shall be developed accordingly to the requirements of the specific application, thus leading to more specialized solutions, with the aim of enhancing the reliability, fault tolerance, and flexibility of the next generation power systems

Improved Wind Turbine Control Strategies for Maximizing Power Output and Minimizing Power Flicker

For reducing the cost of energy (COE) for wind power, controls techniques are important for enhancing energy yield, reducing structural load and improving power quality. This thesis presents the control strategies studies for wind turbine both from the perspectives of both maximizing power output and reducing power flicker and structural load, First, a self-optimizing robust control scheme is developed with the objective of maximizing the power output of a variable speed wind turbine with doubly-fed induction generator (DFIG) operated in Region 2. Wind power generation can be divided into two stages: conversion from aerodynamic power to rotor (mechanical) power and conversion from rotor power to the electrical (grid) power. In this work, the maximization of power generation is achieved by a two-loop control structure in which the power control for each stage has intrinsic synergy. The outer loop is an Extremum Seeking Control (ESC) based generator torque regulation via the rotor power feedback. The ESC can search for the optimal torque constant to maximize the rotor power without wind measurement or accurate knowledge of power map. The inner loop is a vector-control based scheme that can both regulate the generator torque requested by the ESC and also maximize the conversion from the rotor power to grid power. In particular, an ∞ controller is synthesized for maximizing, with performance specifications defined based upon the spectrum of the rotor power obtained by the ESC. Also, the controller is designed to be robust against the variations of some generator parameters. The proposed control strategy is validated via simulation study based on the synergy of several software packages including the TurbSim and FAST developed by NREL, Simulink and SimPowerSystems. Then, a bumpless transfer scheme is proposed for inter-region controller switching scheme in order to reduce the power fluctuation and structural load under fluctuating wind conditions. This study considers the division of Region 2, Region 2.5 and Region 3 in the neighborhood of the rated wind speed. When wind, varies around the rated wind speed, the switching of control can lead to significant fluctuation in power and voltage supply, as well as structural loading. To smooth the switch and improve the tracking, two different bumpless transfer methods, Conditioning and Linear Quadratic techniques, are employed for different inter-region switching situations. The conditioning bumpless transfer approach adopted for switching between Region 2 maximum power capture controls to Region 2.5 rotor speed regulation via generator torque. For the switch between Region 2.5 and Region 3, the generator torque windup at rated value and pitch controller become online to limit the load of wind turbine. LQ technique is posed to reduce the discontinuity at the switch between torque controller and pitch controller by using an extra compensator. The flicker emission of the turbine during the switching is calculated to evaluate power fluctuation. The simulation results demonstrated the effectiveness of the proposed scheme of inter-region switching, with significant reduction of power flicker as well as the damage equivalent load

High Voltage Hybrid Generator and Conversion System for Wind Turbine Applications

This paper presents the design of a high voltage hybrid generator (HG) and conversion system for wind turbine applications. The HG combines wound field (WF) and permanent magnet (PM) rotor excitations. At any given speed, the PM induces a fixed stator voltage while the WF induces a variable controlled stator voltage. The HG alternating output is rectified via a passive rectification stage, hence the machine net DC output voltage is controlled over a prescribed, but limited range. The split ratio between PM and WF rotor sections is considered as varying from a fully WF rotor, or traditional synchronous generator (SG), to some ratio of PM to WF excitation. The turbine operational characteristics and maximum wind velocity variations between turbines in a wind farm are used to define the WF to PM split ratio. Both a 3-phase and a 9-phase stator winding design are investigated. The 9-phase winding results in 4.2% higher output RMS voltage that yields a more power dense solution. It further yields lower rectified DC-link voltage ripple. The HG mass, loss audits and efficiency discussions are presented. In order to investigate the feasibility of the HG concept a small scale laboratory prototype is designed and operational test results presented that show good agreement with the simulation model results

Voltage profile improvement of weak grid with solar PV integration

The objective of this paper is to improve the voltage profile of the grid in pertinence to grid due to power injection from distributed solar photovoltaic (PV) arrays. Weak grids are modeled as worldwide adaptation of net metering, transactive energy systems, and the possibility of further deterioration of power quality with higher grid penetration. In this paper, a solar PV integrated weak distribution grid modelled as the PV arrays being frequently connected in rural areas, due to various reasons like cheap real estate and lack of accessibility. In this paper, three case studies of PV generation are simulated, i.e., scheduled solar PV generation less than load requirement, PV generation equal to load requirement, and PV generation more than load requirement, by considering the daily solar irradiation and load demand profiles of a residential area under study

Flatness-Based Control Methodologies to Improve Frequency Regulation in Power Systems with High Penetration of Wind

To allow for high penetration of distributed generation and alternative energy units, it is critical to minimize the complexity of generator controls and to minimize the need for close coordination across regions. We propose that existing controls be replaced by a two-tier structure of local control operating within a global context of situational awareness. Flatness as an extension of controllability for non-linear systems is a key to enabling planning and optimization at various levels of the grid in this structure. In this study, flatness-based control for: one, Automatic Generation Control (AGC) of a multi-machine system including conventional generators; and two, Doubly fed Induction Machine (DFIG) is investigated. In the proposed approach applied to conventional generators, the local control tracks the reference phase, which is obtained through economic dispatch at the global control level. As a result of applying the flatness-based method, an $n$ machine system is decoupled into n linear controllable systems in canonical form. The control strategy results in a distributed AGC formulation which is significantly easier to design and implement relative to conventional AGC. Practical constraints such as generator ramping rates can be considered in designing the local controllers. The proposed strategy demonstrates promising performance in mitigating frequency deviations and the overall structure facilitates operation of other non-traditional generators. For DFIG, the rotor flux and rotational speed are controlled to follow the desired values for active and reactive power control. Different control objectives, such as maximum power point tracking (MPPT), voltage support or curtailing wind to contribute in secondary frequency regulation, can be achieved in this two-level control structure

Simulator test to study hot-flow problems related to a gas cooled reactor

An advance study of materials, fuel injection, and hot flow problems related to the gas core nuclear rocket is reported. The first task was to test a previously constructed induction heated plasma GCNR simulator above 300 kW. A number of tests are reported operating in the range of 300 kW at 10,000 cps. A second simulator was designed but not constructed for cold-hot visualization studies using louvered walls. A third task was a paper investigation of practical uranium feed systems, including a detailed discussion of related problems. The last assignment resulted in two designs for plasma nozzle test devices that could be operated at 200 atm on hydrogen

Wind Power

This book is the result of inspirations and contributions from many researchers of different fields. A wide verity of research results are merged together to make this book useful for students and researchers who will take contribution for further development of the existing technology. I hope you will enjoy the book, so that my effort to bringing it together for you will be successful. In my capacity, as the Editor of this book, I would like to thanks and appreciate the chapter authors, who ensured the quality of the material as well as submitting their best works. Most of the results presented in to the book have already been published on international journals and appreciated in many international conferences

Transformer-Less Cascaded Voltage Source Converter Based STATCOM

In this work, a transformer-less voltage source converter (VSC) based STATCOM is proposed with a combination of cascaded conventional three-phase voltage source inverters. This modular structure provides multilevel operation with reduced switch count and independent DC-link capacitors. The actual contribution of this paper is the transformer-less configuration of a conventional cascaded voltage source converter which provides reduced cost and volume as compared to other transformer-less converter configurations. The system provides reactive power compensation with better power quality when connected to the nonlinear power electronics load also. A simple control system is provided for balancing the Dc link capacitor voltage and reactive power compensation. The validation of the proposed model is analyzed with simulation using MATLAB/SIMULINK software and the results are obtained with different linear and nonlinear load configurations