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Three-Phase brushless DC motors (BLDC) have become increasingly popular in many fields including industrial controls and remote-control hobby toys. They offer many advantages over their brushed counterparts such as smaller size, longer service life, and increased efficiency; however, one drawback is that commutation must be handled electrically using a controller

Three-Phase brushless DC motors (BLDC) have become increasingly popular in many fields including industrial controls and remote-control hobby toys. They offer many advantages over their brushed counterparts such as smaller size, longer service life, and increased efficiency; however, one drawback is that commutation must be handled electrically using a controller rather than by a mechanical commutator. Rotor position must be estimated in order to accurately commutate the motor, this is calculated either by sensors (sensored) or by measuring the generated Back-Electromotive Force (sensorless). There are two primary methods of brushless DC motor commutation, trapezoidal and sinusoidal. Both methods have advantages and disadvantages, as well as unique sets of rotor position estimation strategies. This paper will discuss in detail the development of a novel motor control algorithm that employs one method of sensorless trapezoidal control of BLDC motors where the BEMF is integrated after a zero-crossing event, the various challenges associated with direct BEMF measurement, and demonstrate a practical implementation of the new algorithm. Using a robust, high frequency sampling scheme and on-the-fly detection strategies, this new algorithm overcomes many of the shortcomings of similar control algorithms currently available on the market. As a result, this new algorithm provides even more robust control over BLDC motors, increased efficiency, and improved dynamic performance compared to its counterparts while simultaneously requiring little to no additional hardware in practical implementations. Topics investigated include BLDC motors, sensored and sensorless rotor estimation, PWM strategies, terminal voltage sensing, third harmonic voltage sensing and integration, sample timing, switching noise, and current recirculation.
ContributorsYin, Kai (Author) / Chickamenahalli, Shamala (Thesis director) / Holbert, Keith (Committee member) / Computer Science and Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-12
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Breast cancer affects about 12% of women in the US. Arguably, it is one of the most advertised cancers. Mammography became a popular tool of breast cancer screening in the 1970s, and patient-geared guidelines came from the American Cancer Society (ACS) and the US Preventative Task Force (USPSTF). This research

Breast cancer affects about 12% of women in the US. Arguably, it is one of the most advertised cancers. Mammography became a popular tool of breast cancer screening in the 1970s, and patient-geared guidelines came from the American Cancer Society (ACS) and the US Preventative Task Force (USPSTF). This research focuses on ACS guidelines, as they were the earliest as well as the most changed guidelines. Mammography guidelines changed over time due to multiple factors. This research has tracked possible causes of those changes. Research began with an extensive literature search of clinical trials, the New York Times and the Washington Post archives, systematic reviews, ACS and USPSTF archives.

Created2021-02-16
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Science fiction works can reflect the relationship between science and society by telling stories that are set in the future of ethical implications or social consequences of scientific advancements. This thesis investigates how the concept of reproduction is depicted in popular science fiction works.

Created2021-02-10
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By questioning methods of sex selection since their early development, and often discovering that they are unreliable, scientists have increased the creative and technological capacity of the field of reproductive health. The presentation of these methods to the public, via published books on timing methods and company websites for sperm

By questioning methods of sex selection since their early development, and often discovering that they are unreliable, scientists have increased the creative and technological capacity of the field of reproductive health. The presentation of these methods to the public, via published books on timing methods and company websites for sperm sorting, increased interest in, and influence of, sex selection within the global society. The purpose of explaining the history, interest, development, and impact of various sex selection methods in the mid-twentieth century based on the information that is available on them today is to show couples which methods have failed and provide them with the knowledge necessary to make an informed decision on how they choose to go about utilizing methods of sex selection.

Created2021-02-26
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By demonstrating the struggle for sound standard of care for non-medical reproductive health care providers during the nineteenth and early twentieth century, this project emphasizes what the standards of reproductive health care for abortion and contraception might be like if the organizations that made them so readily available, like Planned

By demonstrating the struggle for sound standard of care for non-medical reproductive health care providers during the nineteenth and early twentieth century, this project emphasizes what the standards of reproductive health care for abortion and contraception might be like if the organizations that made them so readily available, like Planned Parenthood, were defunded or criminalized in our modern setting.

Created2021-02-23
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On 29 June 1988, in Bowen v. Kendrick, the US Supreme Court ruled in a five-to-four decision that the 1981 Adolescent Family Life Act, or AFLA, was constitutional. Under AFLA, the US government could distribute federal funding for abstinence-only sexual education programs, oftentimes given to groups with religious affiliations. As

On 29 June 1988, in Bowen v. Kendrick, the US Supreme Court ruled in a five-to-four decision that the 1981 Adolescent Family Life Act, or AFLA, was constitutional. Under AFLA, the US government could distribute federal funding for abstinence-only sexual education programs, oftentimes given to groups with religious affiliations. As a federal taxpayer, Chan Kendrick challenged the constitutionality of AFLA, claiming it violated the separation of church and state. The Supreme Court found that although AFLA funded programs that aligned with certain religious ideologies, it was constitutional because it did not encourage government involvement in religion, and it held a valid secular purpose in seeking to prevent adolescent pregnancy and premarital sexual relations. By upholding AFLA, Bowen v. Kendrick enabled the US government to continue funding abstinence-only education, which researchers have found to be ineffective.

Created2021-02-26
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In 1997, physicians and researchers Ambre Olsen, Virginia Smith, John Bergstrom, Joyce Colling, and Amanda Clark published, “Epidemiology of Surgically Managed Pelvic Organ Prolapse and Urinary Incontinence,” in the journal Obstetrics and Gynecology. In their article, the authors retrospectively analyzed data from patients who underwent surgery for pelvic organ prolapse

In 1997, physicians and researchers Ambre Olsen, Virginia Smith, John Bergstrom, Joyce Colling, and Amanda Clark published, “Epidemiology of Surgically Managed Pelvic Organ Prolapse and Urinary Incontinence,” in the journal Obstetrics and Gynecology. In their article, the authors retrospectively analyzed data from patients who underwent surgery for pelvic organ prolapse or urinary incontinence two years prior in 1995. Often due to a weakening of or damage to their pelvic muscles, women with pelvic organ prolapse can experience a descent of pelvic organs into the lower pelvis and vagina. People with urinary incontinence can experience bladder control issues and urinary leaks. According to the authors, an estimated fifty percent of women who have previously given birth have had a prolapse. In their article, Olsen and colleagues analyze factors such as race, age, and weight in women who had surgery to treat pelvic organ prolapse and ultimately advocate for a standard assessment for the severity of those conditions.

Created2021-02-23
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In 1996, a team of researchers associated with the International Continence Society published “The Standardization of Terminology of Female Pelvic Organ Prolapse and Pelvic Floor Dysfunction” in American Journal of Obstetrics and Gynecology. Pelvic organ prolapse is characterized by the descent of the pelvic organs into the lower portion of

In 1996, a team of researchers associated with the International Continence Society published “The Standardization of Terminology of Female Pelvic Organ Prolapse and Pelvic Floor Dysfunction” in American Journal of Obstetrics and Gynecology. Pelvic organ prolapse is characterized by the descent of the pelvic organs into the lower portion of the pelvis and is often caused by a weakening of the muscles and ligaments that normally hold the organs in place. The authors concluded that physicians and researchers needed to develop a system of standardized terms to use to describe the anatomical position of pelvic organ prolapse in women. They propose using terms that emphasize the location of the prolapse rather than just the involved organ. They also suggest that the system utilizes a series of examinations and imaging to uniformly describe and quantify pelvic organ prolapse. The article by Bump and colleagues was one of the first to call for a standardized system using specific terms to communicate findings about pelvic organ prolapse systematically across clinical and academic research settings.

Created2021-03-10
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In 2013, Cynthia Daniels and a team of researchers at Rutgers University in New Brunswick, New Jersey, founded the Informed Consent Project. Daniels and the researchers assessed the medical accuracy of information within state-authored informational materials for abortion. States give those materials to women who want an abortion, but using

In 2013, Cynthia Daniels and a team of researchers at Rutgers University in New Brunswick, New Jersey, founded the Informed Consent Project. Daniels and the researchers assessed the medical accuracy of information within state-authored informational materials for abortion. States give those materials to women who want an abortion, but using their research, the Informed Consent Project found some information from those materials to be inaccurate, misleading, and coercive. The Informed Consent Project gathered a panel of researchers and medical specialists to review the information about embryological and fetal development from twenty-three states’ informational materials. They found that approximately one-third of that information was inaccurate. The work of the Informed Consent Project challenges abortion-specific informed consent laws, highlighting medical inaccuracies in state-authored informational materials as evidence that women’s consent to abortion may be based on false or misleading statements.

Created2021-06-01
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In 1983, researchers Alan Trounson, John Leeton, Carl Wood, Mandy Besanko, and Angelo Conti published the article “Pregnancy Established in an Infertile Patient After Transfer of a Donated Embryo Fertilized In Vitro” in The British Medical Journal. In the article, the authors discuss one of the first successful experiments using

In 1983, researchers Alan Trounson, John Leeton, Carl Wood, Mandy Besanko, and Angelo Conti published the article “Pregnancy Established in an Infertile Patient After Transfer of a Donated Embryo Fertilized In Vitro” in The British Medical Journal. In the article, the authors discuss one of the first successful experiments using in vitro fertilization, or IVF, with the use of a human donor embryo at the Monash University and Queen Victoria Medical Center in Melbourne, Australia. Prior to the article’s publication, it was uncertain whether scientists could successfully use human donor embryos in IVF techniques. Although the pregnancy ended in a miscarriage ten weeks later, it showed that IVF was possible for those who needed to use someone else’s donated egg cells. Trounson and his colleagues’ paper provided a basis for future IVF pregnancies using donated embryos and helped develop a treatment option for men and women who could not conceive through sexual intercourse alone.

Created2021-04-13