Torque Measurement and Control for Electric-Assisted Bike Considering Different External Load Conditions.

This paper proposes a novel torque measurement and control technique for cycling-assisted electric bikes (E-bikes) considering various external load conditions. For assisted E-bikes, the electromagnetic torque from the permanent magnet (PM) motor can be controlled to reduce the pedaling torque generated by the human rider. However, the overall cycling torque is affected by external loads, including the cyclist's weight, wind resistance, rolling resistance, and the road slope. With knowledge of these external loads, the motor torque can be adaptively controlled for these riding conditions. In this paper, key E-bike riding parameters are analyzed to find a suitable assisted motor torque. Four different motor torque control methods are proposed to improve the E-bike's dynamic response with minimal variation in acceleration. It is concluded that the wheel acceleration is important to determine the E-bike's synergetic torque performance. A comprehensive E-bike simulation environment is developed with MATLAB/Simulink to evaluate these adaptive torque control methods. In this paper, an integrated E-bike sensor hardware system is built to verify the proposed adaptive torque control.

High-Resolution Permanent Magnet Drive Using Separated Observers for Acceleration Estimation and Control.

This paper proposes a high-resolution permanent magnet (PM) motor drive based on acceleration estimation and control. The PM motor is widely implemented in the printed circuit board (PCB) manufacturing process. To achieve the demanded 1 µm drilling resolution, a sine/cosine incremental encoder is usually installed for motion control. In this paper, several improvements are developed to increase the motion control steady-state accuracy balancing transient response. First, the interpolation of every two encoder counts is proposed to increase the position sensing resolution. In this case, the transient response is improved through the high-resolution position feedback. Second, a closed-loop observer with two independent bandwidths is proposed for acceleration estimation. By using the interpolated position for acceleration estimation, the vibration-reflected high-frequency torque harmonics can be compensated through the acceleration closed-loop control. It reduces the steady-state error under the same sensing hardware. According to experimental results, both transient response and steady-state error can be improved on a PM motor using the proposed position interpolation and acceleration control.

Sensorless LC Filter Implementation for Permanent Magnet Machine Drive Using Observer-Based Voltage and Current Estimation.

For pulse width modulation (PWM) inverter drives, an LC filter can cascade to a permanent magnet (PM) machine at inverter output to reduce PWM-reflected current harmonics. Because the LC filter causes resonance, the filter output current and voltage are required for the sensorless field-oriented control (FOC) drive. However, existing sensors and inverters are typically integrated inside commercial closed-form drives; it is not possible for these drives to obtain additional filter output signals. To resolve this integration issue, this paper proposes a sensorless LC filter state estimation using only the drive inside current sensors. The design principle of the LC filter is first introduced to remove PWM current harmonics. A dual-observer is then proposed to estimate the filter output current and voltage for the sensorless FOC drive. Compared to conventional model-based estimation, the proposed dual-observer demonstrates robust estimation performance under parameter error. The capacitor parameter error shows a negligible influence on the proposed observer estimation. The filter inductance error only affects the capacitor current estimation at high speed. The performance of the sensorless FOC drive using the proposed dual-observer is comparable to the same drive using external sensors for filter voltage and current measurement. All experiments are verified by a PM machine with only 130 µH phase inductance.

Access to and use of $4 generic programs in Medicare.

BACKGROUND: Although four-dollar programs ($4 per 30-day supply for selected generic drugs) have become important options for seniors to obtain affordable medications, little is known about access to these programs and the characteristics of those who use them. OBJECTIVES: We quantify access to $4 programs based on driving distance; evaluate factors affecting the program use and potential cost-savings associated with switching to $4 programs in Medicare. DESIGN: Observational study. SETTING: US Medicare Part D data, 5% random sample, 2007 PARTICIPANTS: 347,653 elderly beneficiaries without Medicaid coverage or low-income subsidies. MAIN MEASURES: We evaluated how use of $4 programs was affected by driving distance to the store and the beneficiary's demographic and socioeconomic status, insurance coverage, health status, comorbidities, and medication use. For those who did not use the $4 programs, we calculated potential savings from switching to $4 generics. KEY RESULTS: Eighty percent of seniors in Medicare Part D filled prescriptions for generic drugs that were commonly available at $4 programs. Among them, only 16.3% filled drugs through $4 programs. Beneficiaries who lived in poor areas, had less insurance, more co-morbidities, and used more drugs and lived closer to $4 generic retail pharmacies, were more likely to use these programs. Blacks were less likely to use the program relative to Whites (15.0% vs. 16.4%; OR=0.75, 95% CI 0.71-0.80). While 53.2% of nonusers would save by switching to $4 program after incorporating travelling costs, 58% of those who could save would have net annual out-of-pocket savings of less than $20. CONCLUSIONS: The take-up rate of $4 programs was low in 2007 among Medicare beneficiaries. As more stores offer $4 programs and increasing numbers of drugs become generic, more beneficiaries could potentially benefit, as could the Medicare program.

A water-soluble ribosyl-based fluorescent sensor for Hg2+ and Cu2+ ions.

A water-soluble ribosyl-based fluorescent sensor 5 was prepared. The sensor contains an anthracene as the fluorophore and a set of complex groups as recognition sites, which bears two triazole ring spacers linked to two ribosyl carboxylic acids groups. The association constants of 5 in water are 2.15x10(5)M(-1) and 9.57x10(4)M(-1) for Cu(2+) and Hg(2+) ions, respectively, and both metals formed complexes with 5 at a 1:1 metal to ligand ratio. The binding of 5 to Cu(2+) shows a broad pH range (5-10) and a low detection limit (57ppb) in water, thus indicating it an efficient and promising cation probe.

Revisiting with a relative-density calibration approach the determination of growth rates of microorganisms by use of optical density data from liquid cultures.

To solve the problems of measuring the growth rates of microorganisms from optical density (OD)-growth time plots, we used relative-density (RD) plots. The relationship of OD and RD was built from the diluted grown cultures. This method was satisfactorily applied to study the growth of Escherichia coli and the cyanobacterium Anabaena spiroides.

A comparison of the effects of thought suppression, distraction and concentration.

This study compared the effects of suppression, focused-distraction, and concentration on controlling unwanted distressing thoughts, and examined how anxiety levels were associated with the use of each thought-control technique. In the study, college students were told to suppress thoughts about a distressing story, to suppress the same thoughts by focusing on an alternative distraction task, to simply concentrate on that alternative task, or to think about anything without restrictions for 6minutes. This initial period was followed by a "free-thinking" period to assess the delayed effect of thought-control techniques. The results indicated that focused-distraction and concentration led to fewer intrusions of target thoughts than suppression, and concentration in turn resulted in fewer target intrusions than focused-distraction during the initial period. Participants in the focused-distraction and concentration condition also tended to report lower anxiety during the initial period than those who were told to suppress thoughts.

Effective generation of transgenic pigs and mice by linker based sperm-mediated gene transfer.

BACKGROUND: Transgenic animals have become valuable tools for both research and applied purposes. The current method of gene transfer, microinjection, which is widely used in transgenic mouse production, has only had limited success in producing transgenic animals of larger or higher species. Here, we report a linker based sperm-mediated gene transfer method (LB-SMGT) that greatly improves the production efficiency of large transgenic animals. RESULTS: The linker protein, a monoclonal antibody (mAb C), is reactive to a surface antigen on sperm of all tested species including pig, mouse, chicken, cow, goat, sheep, and human. mAb C is a basic protein that binds to DNA through ionic interaction allowing exogenous DNA to be linked specifically to sperm. After fertilization of the egg, the DNA is shown to be successfully integrated into the genome of viable pig and mouse offspring with germ-line transfer to the F1 generation at a highly efficient rate: 37.5% of pigs and 33% of mice. The integration is demonstrated again by FISH analysis and F2 transmission in pigs. Furthermore, expression of the transgene is demonstrated in 61% (35/57) of transgenic pigs (F0 generation). CONCLUSIONS: Our data suggests that LB-SMGT could be used to generate transgenic animals efficiently in many different species.