Variable gain control of brushless DC motor control with low resolution sensors

In this work, feasibility of using low cost, low resolution sensor for high performance brushless dc (BLDC) motor speed control is investigated. Conventional control, using a tachometer or high resolution encoder, suffers from drawbacks such as high cost, large physical volume, and high sensor processing bandwidth. On the other hand, sensorless BLDC motor, appealing in its hardware simplicity, does not provide sufficient fast performance. Using a standard low resolution sensor, such as a hall sensor or commutation encoder, a compromise between cost and performance can be obtained. However, the use of a low resolution sensor does pose a challenge to the control design: the sensor signal is discrete and speed dependent. Together with the nonlinear drive voltage/speed characteristic of the motor, control of the BLDC motor requires a more advanced algorithm than fixed gain control. This thesis presents a speed dependent control scheme to produce optimal performance. The characteristics of the control scheme is first assessed by numerical simulation, based on the mathematical model of the BLDC motor. This is followed by experimental verification of the BLDC motor. From the available data, it is concluded that speed dependent control provides significant advantages over fixed gain control when low resolution sensor is used

Time-Based Separation for Aircraft Landing Using Danger Value Distribution Flow Model

This study proposes a flow model using a modified Lighthill-Whitham-Richards highway model. The proposed model treats each aircraft on an airway as a continuous distribution of air collision probability, which is called the danger value distribution. With the proposed flow model, collision can be easily predicted by the peak value of the overlap of the danger value distribution of each aircraft. The study further proposes a velocity adjustment method that can be used to resolve the conflict. The proposed method can be applied for aircraft separation during the landing process, in which the separation time is different for different combinations of aircraft types

Qubit Mapping Toward Quantum Advantage

Qubit Mapping is a pivotal stage in quantum compilation flow. Its goal is to convert logical circuits into physical circuits so that a quantum algorithm can be executed on real-world non-fully connected quantum devices. Qubit Mapping techniques nowadays still lack the key to quantum advantage, scalability. Several studies have proved that at least thousands of logical qubits are required to achieve quantum computational advantage. However, to our best knowledge, there is no previous research with the ability to solve the qubit mapping problem with the necessary number of qubits for quantum advantage in a reasonable time. In this work, we provide the first qubit mapping framework with the scalability to achieve quantum advantage while accomplishing a fairly good performance. The framework also boasts its flexibility for quantum circuits of different characteristics. Experimental results show that the proposed mapping method outperforms the state-of-the-art methods on quantum circuit benchmarks by improving over 5% of the cost complexity in one-tenth of the program running time. Moreover, we demonstrate the scalability of our method by accomplishing mapping of an 11,969-qubit Quantum Fourier Transform within five hours

Unusual dyspnea in a hemodialysis patient: A case report

The typical clinical symptoms of hemothorax include a rapid development of chest pain or dyspnea, which may be life-threatening without immediate management. As we know, spontaneous hemothorax, a collection of blood within the pleural cavity without previous history of trauma or other cause, which usually onsets suddenly. The early and accurate diagnosis of spontaneous hemothorax is imperative in clinical practice. We reported a middle-age male undergoing regular hemodialysis was referred to our emergency department due to unknown cause of dyspnea and acute respiratory failure. Chest radiography revealed bilateral patchy infiltration of lung. Pleural tap analysis showed exudative pleural effusion with numerous red blood cells. Video-assisted thoracic surgery (VATS) were performed and confirmed the final diagnosis of spontaneous hemothorax. He was then successfully treated with the surgery of VATS combined chest tube thoracostomy