Fuzzy logic controller and cascade inverter for direct torque control of IM

In this paper, a five-level cascaded H-bridge multilevel inverters topology is applied on induction motor control known as direct torque control (DTC) strategy. More inverter states can be generated by a five-level inverter which improves voltage selection capability. This paper also introduces two different control methods to select the appropriate output voltage vector for reducing the torque and flux error to zero. The first is based on the conventional DTC scheme using a pair of hysteresis comparators and look up table to select the output voltage vector for controlling the torque and flux. The second is based on a new fuzzy logic controller using Sugeno as the inference method to select the output voltage vector by replacing the hysteresis comparators and lookup table in the conventional DTC, to which the results show more reduction in torque ripple and feasibility of smooth stator current. By using Matlab/Simulink, it is verified that using five-level inverter in DTC drive can reduce the torque ripple in comparison with conventional DTC, and further torque ripple reduction is obtained by applying fuzzy logic controller. The simulation results have also verified that using a fuzzy controller instead of a hysteresis controller has resulted in reduction in the flux ripples significantly as well as reduces the total harmonic distortion of the stator current to below 4 %.

Digital literacies in the middle years of schooling

This paper uses Glister's interpretation of digital literacy whilst acknowledging that a computer is not the only means for the delivety of digital texts. I will explore how we can support student teachers to develop understandings about the teaching in the middle years in order to work with students in schools to successfully read digital texts, create digital texts, search, fmd and use information in the digital world and to become critical users of digital texts. Students in the middle years of schooling are facing increasingly sophisticated literacy demands of new technologies that go well beyond that of the traditional printed page as they interact with information communicated through a range of digital media both inside and outside of school. At best new technologies can open doors to students for researching and accessing a world far beyond their own environment, empowering them to direct and control their own learning and produce quality work.

Political transition in Myanmar: prospects and problems

Since 2011, Myanmar has been undergoing a political transition that, in keeping with the Myanmar government's own claims, has been hailed by many previously critical countries as the start of a process of democratization. Myanmar has become a substantially more liberal country, and in particular its economy has been increasingly liberalized, away from the tight restrictions of the past. However, Myanmar's economic liberalization primarily benefits its entrenched and usually military-dominated or linked elites, while its political liberalization may be just enough to satisfy an appearance of democratization without the army giving up real power. This article looks at Myanmar's process of political liberalization set against some of the literature on political transitions, and highlights some factors that could militate against extensive reform, much less democratization. It concludes by noting that while Myanmar's military has started to step back from direct political control, it still retains ultimate state authority. © 2014 Policy Studies Organization.

Seasonal timing of the spring departure of waders from the Banc D'Arguin, Mauritania

The northward departure of 13 wader species was studied in the Baie d' Aouatif, Bane d'Arguin, Mauritania, in the springs of 1985, 1986 and 1988. Waders left the area in the late afternoon. Wind speed and direction were registered near ground level (all years) and at altitudes up to 5 km (in 1988). A total of 31 000 waders were observed heading northwards, with those species wintering locally in largest numbers being most common. The majority of wader species showed fairly short periods of departure and unimodal departure peaks. Redshank and Dunlin departed over extended periods. Average departure dates of species correlated positively with the estimated midpoints of ranges in breeding latitude (ca. 2 d per 0 latitude).  Since winds at ground level did not correlate with winds at higher altitudes, and since it is likely that the departing waders traveled at great heights, it was not surprising that there is no correlation between the average afternoon tail wind vector at ground level and the daily departure intensity. We suggest that the timing ofdeparture from the Bane d'Arguin is largely under internal, instead of under direct environmental, control.

Modelling and simulation of regeneration in AC traction propulsion system of electrified railway

This paper presents a robust model and its simulation to investigate the performance of an AC propulsion system in a rail vehicle for directly returning the regenerative braking power to the feeder substation of an AC traction network. This direct returning method can be an efficient approach for energy recovery if the regenerative braking is reliably applied. However, it is shown that this method can cause undesired voltage fluctuations if the regenerative braking regime or braking location of the rail vehicle change. The load torque on the traction motor (TM) is precisely modelled when pure electrical braking is applied. Different states of the direct torque controlled inverter are modelled when the TM regenerates. A circuit model for the utility grid, load impedances and the traction network is developed to evaluate the network receptivity against the regenerated power. The dynamics of the electromagnetic torque and the fluctuations of the DC-link voltage are investigated for two operational conditions: changes on the regenerative braking regime and changes on the rail vehicle braking location. The results justify how the DC-link voltage dramatically fluctuates with variations of the rail vehicle's operation conditions, whereas the electromagnetic torque is maintained on optimum rates.

Heavy tools manipulation by low powered direct-drive five-bar parallel robot

This paper presents a simple and available system for manipulation of heavy tools by low powered manipulator for industrial applications. In the heavy manufacturing industries, sometimes, heavy tools are employed for different types of work. But the application of robots with heavy tools is not possible due to the limited torque limits of actuators. Suspended tool systems (STS) have been proposed to manipulate heavy tools by low powered robot-arm for this purpose. A low powered five-bar direct-drive parallel manipulator is designed and constructed to manipulate heavy tools suspended from a spring balancer. The validity, usefulness, and effectiveness of the suspended tool system are shown by experimental results.

Mediated and direct effects of general control beliefs on obsessive compulsive symptoms

Although control-related cognitions have often been implicated in discussions of obsessive compulsive disorder (OCD), empirical investigations of the relationship between control constructs and OCD symptoms have been relatively limited. This article investigated the hypothesis that OCD symptoms may be linked with a higher desire for control (DC), but a lower sense of control (SC) over the self and environment, leading to motivation for compulsive symptoms. It also investigated whether this effect was direct, or mediated through other OCD-related cognitions. This hypothesis was investigated in a nonclinical population, using path analyses controlling for depression. It was found that higher levels of DC and lower levels of SC were associated with higher levels of OCD-related beliefs, and with symptoms via higher OCD-related beliefs. SC was also directly linked with higher OCD symptoms. Control beliefs regarding both the internal (emotions) and external (threat) environment were related to OCD symptoms. Implications for therapy and research are discussed.

Cold rolling mill thickness control using the cascade-correlation neural network

The improvements in thickness accuracy of a steel strip produced by a tandem cold-roIling mill are of substantial interest to the steel industry. In this paper, we designed a direct model-reference adaptive control (MRAC)  scheme that exploits the natural level of excitation existing in the closed-loop with a dynamically constructed cascade-correlation neural network (CCNN) as a controller for cold roIling mill thickness control. Simulation results show that the combination of a such a direct MRAC scheme and the dynamically constructed CCNN significantly improves the thickness accuracy in the presence of disturbances and noise in comparison with to the conventional PID controllers.

The long and the short of flagellar length control

Discusses key issues concerning the length control of flagellates. How the cell maintains the consistency of length; Final flagellar length achieved when the rate of flagellar assembly slows down to a point where it exactly balances the rate of flagellar disassembly; Implications on phycology.

Teachers' work hours, work-family conflict and health: the mediating effects of perceived control and organisational support

Teachers are among those working longer hours more than ever before. the implications of these long hours on teachers' health, through work-family conflict, control over hours worked and organisational support were investigated. 120 teachers, of whom 91 (59.3% female) reported
working in excess of 37 1/2 hours in the week prior, participated in the study. Long hours, work-family conflict, control and organisational support, explained 69% of the variance in health. There was no direct effect of long worked hours on health however long hours did have a direct impact on work-family conflict, organisational support, and control and, through
these, teachers' health. Work-family conflict exerted a direct negative impact on health. These findings are discussed in individual and organisational tenns.

Control loop for finding initial translator position of linear synchronous motor

This article presents a simple and reliable method for controlling the relative orientation between the two magnetic fields of a permanent magnet synchronous motor. Finding the initial (at motor powering- up time) value of this relative location is essential for the proper operation of the motor. After showing the system controllability, the utilized feedback control loop finds this initial relative orientation quickly and accurately. Further, using the proposed method allows considerable cost saving, as a transducer that is usually used for this purpose can be eliminated. The cost saving is most obvious in the case of linear motors and angle motors with large diameters. The way the problem is posed is an essential part of this work, and it is the reason behind the apparent simplicity of the solution. The method proposed relies on a single sensor, and it was tested when a relative encoder was used.

Terrify and control: the politics of risk society

The article presents information on the idea of risk management. The origins of the contemporary constructions of risk are found in the seventeenth century, with the development of maritime insurance. In the context of maritime trading, risk came to be seen in terms of the balance between acquisitive opportunities and potential dangers and calculations of future loss of a ship or cargo. Today perceptions of risk affect our actions and strategies in areas of our life as diverse as health, parenting, crime prevention, recreation and travel. Public policy tends to be focused around risk avoidance and risk management, particularly in areas of child protection and aged care. While most of the discussions of risk have focused on risks as bads in society, risk has also been identified as a good. Risk is deemed a good when it challenges people to think differently and creatively. From a neo-liberal perspective risk opens up opportunities for unleashing of entrepreneurial capacity. In the context of the modernist commitment to the idea that people have the potential to control their own destiny, identification of threats and dangers can energize people to be adventurous. The discourse of risk has framed all the reports of the outbreaks of new strains of infection and includes instructions on how to recognize the risk assessments of its spread and instructions on how to avoid its spread.

Interpersonal trust and control behaviour of Chinese managers

Interpersonal trust is believed to influence the management and control of organisations in China. China's importance as a host country for foreign direct investments (FDIs) through multinational company subsidiaries (MNCs) and international joint ventures (IJVs) is growing rapidly. MNCs and INs located in China often employ local Chinese managers to control their subsidiaries or ventures. This makes it essential for designers of management control systems to have an understanding of the interpersonal trust-sensitive control behaviour of Chinese managers. One of the important aspects of control behaviour is how managers control their subordinates.

This paper examines the relationship between Chinese managers' trust in subordinates and their (Chinese managers') control behaviour towards the subordinates. On the basis of a questionnaire survey of a cohort of managers from Beijing, the study explores the effects of trust on the use of social controls, formal controls, and monitoring.

The findings of this study indicate that a manager's high (low) trust in a subordinate is associated with a low (high) level of monitoring, a high (high) level of social control and a high (low) level of perceived performance. The hypothesis that a superior's high (low) level of trust is associated with a low (high) level of reliance on formal controls was not supported. These findings, while indicative of control behaviour of Chinese managers in particular, also add to the growing academic literature on trust and control in general. In a practical sense, an
understanding of the trust-sensitive control behaviour of Chinese managers is particularly useful in designing and implementing effective control systems for international organisations operating in China.

Automated robotic grinding by low-powered manipulator

A new robotic grinding process has been developed for a low-powered robot system using a spring balancer as a suspension system. To manipulate a robot-arm in the vertical plane, a large actuator torque is required due to the tool weight and enormous gravity effect. But the actuators of the robot system always exhibit a limited torque capacity. This paper presents a cheap and available system for precise grinding tasks by a low-powered robot system using a suspension system. For grinding operations, to achieve position and force-tracking simultaneously, this paper presents an algorithm of the hybrid position/force-tracking scheme with respect to the dynamic behavior of a spring balancer. Material Removal Rate (MRR) is developed for materials SS400 and SUS304. Simulations and experiments have been carried out to demonstrate the feasibility of the proposed system.

Eccentricity and hardness control in cold rolling mills with a dynamically constructed neural controller

The main objective of a steel strip rolling process is to produce high quality steel at a desired thickness.  Thickness reduction is the result of the speed difference between the incoming and the outgoing steel strip and the application of the large normal forces via the backup and the work rolls.  Gauge control of a cold rolled steel strip is achieved using the gaugemeter principle that works adequately for the input gauge changes and the strip hardness changes.  However, the compensation of some factors is problematic, for example, eccentricity of the backup rolls.  This cyclic eccentricity effect causes a gauge deviation, but more importantly, a signal is passed to the gap position control so to increase the eccentricity deviation.  Consequently, the required high product tolerances are severely limited by the presence of the roll eccentricity effects.
In this paper a direct model reference adaptive control (MRAC) scheme with dynamically constructed neural controller was used.  The aim here is to find the simplest controller structure capable of achieving an optimal performance.  The stability of the adaptive neural control scheme (i.e. the requirement of persistency of excitation and bounded learning rates) is addressed by using as the inputs to the reference model the plant's state variables.  In such a case, excitation is due to actual plant signals (states) affected by plant disturbances and noise.  In addition, a reference model in the form of a filter with a desired transfer function using Modulus Optimum design was used to ensure variance in the desired dynamic characteristics of the system.  The gradually decreasing learning rate employed by the neural controller in this paper is aimed at eliminating controller instability resulting from over-aggressive control.  The moving target problem (i.e. the difficulty of global neural networks to perfrom several separate computational tasks in closed -loop control) is addressed by the localized architecture of the controller.  The above control scheme and learning algorithm offers a method for automatic discovery of an efficient controller.
The resulting neural controller produces an excellent disturbance rejection in both cases of eccentricity and hardness disturbances, reducing the gauge deviation due to eccentricity disturbance from 33.36% to 4.57% on average, and the gauge deviation due to hardness disturbance from 12.59% to 2.08%.