Energy Harvesting from Exercise Machines: Comparative Study of EHFEM Performance with DC-DC Converters and Dissipative Overvoltage Protection Circuit

Energy Harvesting from Exercise Machines (EHFEM) is an ongoing project pursuing alternate forms of sustainable energy for Cal Poly State University. The EHFEM project seeks to acquire user-generated DC power from exercise machines and sell that energy back to the local grid as AC power. The end goal of the EHFEM project aims to integrate a final design with existing elliptical fitness trainers for student and faculty use in Cal Poly’s Recreational Center. This report examines whether including the DC-DC converter in the EHFEM setup produces AC power to the electric grid more efficiently and consistently than an EHFEM system that excludes a DC-DC converter. The project integrates an overvoltage protection circuit, a DC-DC converter, and a DC-AC microinverter with an available elliptical trainer modified to include an energy converting circuit. The initial expectation was that a DC-DC converter would increase, when averaged over time, the overall energy conversion efficiency of the EHFEM system, and provide a stable voltage and current level for the microinverter to convert DC power into AC power. In actuality, while including a DC-DC converter in a test setup allows the EHFEM system to function with less frequent interruptions, this occurs at the cost of lower efficiency. Testing demonstrates the EHFEM project can convert user-generated DC mechanical power into usable AC electrical power. Retrofitting existing equipment with the EHFEM project can reduce Cal Poly’s energy cost

The District of Columbia Retirement Reform Act of 1979: Was Eliminating the Aggravation Clause an Unwarranted Remedy?

These comments are part of Developments of the Law in the District of Columbia

The District of Columbia Retirement Reform Act of 1979: Was Eliminating the Aggravation Clause an Unwarranted Remedy?

These comments are part of Developments of the Law in the District of Columbia

Protection System For the Energy Harvesting from Exercise Machines (EHFEM) Project

The goal of the Energy Harvesting from Exercise Machines (EHFEM) project seeks to harness the energy generated by people using exercise machines and deliver this energy to the electric grid [1]. The implementation consists of a protection system, DC-DC converter, and an inverter. This project involves redesigning the existing DC-DC input protection circuit and current limiter for the EHFEM project [2]. The DC-DC converter takes in the power from the exercise machines and converts it to a manageable voltage level for the inverter. Due to a problem where the inverter may overload the converter, a current limiter sets to limit the current between the two circuits [4]. The inverter demanding more current at a lower voltage than the DC-DC converter can provide causes this overload. The input protection circuit for the DC-DC converter presents another major component of the protection system. The DC-DC converter must operate within set input voltage and current parameters. Concurrent with this project, students Byung Yoo and Sheldon Chu have developed a new DC-DC converter design with an operational range of 6 V to 51 V [7]. This paper proposes a design for an overvoltage protection circuit to limit the input of Yoo’s and Chu’s DC-DC converter to within its operational range. The input protection circuit regulates the incoming voltage from the elliptical machine and filters out any high frequency transient responses with capacitive filtering to generate a smooth DC signal. The circuit also functions to divert excess voltage and current that accumulates during the Enphase Micro-inverter’s startup period where an open load appears across the DC-DC converter leading to an overvoltage level [3]. A current sense circuit ensures the output from the DC-DC converter to the inverter delivers only as much power as the inverter can convert [4]. The device maintains a minimal component count number and lacks any excessively large components permitting easy assembly and installation. The device operates with a minimal loss of energy and minimizes fabrication costs allowing for recuperation of initial production costs over 10 years of normal use

Do Biases Exist in the Location of Affordable Housing? An Examination of the Low-Income Housing Tax Credit in North Carolina

This paper first establishes the importance of the Low-Income Housing Tax Credit (LIHTC) as a subsidy for the production of affordable housing in the United States, and then examines LIHTC allocation patterns in North Carolina in an attempt to determine possible biases in the production process. Analysis of allocation data shows a strong correlation between the presence of commercial bank branches and LIHTC allocation patterns on a county-by-county basis, even after controlling for population. Through a detailed analysis of allocation patterns and interviews with key informants in the LIHTC industry, three possible biases are suggested. First, LIHTC developers and properties may be spatially correlated due to time and cost savings as well as a need for specialized knowledge and local relationships. Second, the financial involvement of local government may be an important factor in development decisions both as a result of state finance agency regulations and implications for financial feasibility. Finally, decisions made by LIHTC investors may be playing a role in location decisions, although the extent of this role can be debated. The production of affordable housing through the Low-Income Housing Tax Credit (LIHTC) program is neither perfectly efficient nor of sufficient scope to completely solve housing affordability problems in the United States. However, affordable housing advocates should be aware of the significant victory that the program represents for those in need of housing assistance given the climate that social programs have faced both before and since the creation of the LIHTC in 1986. The combination of an ever-worsening budgetary climate, a continued emphasis on devolution with respect to social programs formerly sponsored by the Federal government, and the shift from the provision of multifamily housing assistance to homeownership assistance by the U.S. Department of Housing and Urban Development (HUD) represent a very real threat to the survival of the LIHTC. Affordable housing advocates would be well advised to protect and maximize the efficient use of resources that are currently available from the Federal government until a political climate that allows for the expansion of social programs arises once again. This paper examines issues surrounding the operation and survival of the LIHTC in two parts. First, the political climate surrounding affordable housing policy over the past four decades is examined, with a goal of establishing the improbability of the creation of the LIHTC as well as an argument for its importance to current affordable housing provision in the United States; and second, allocation patterns of the LIHTC in North Carolina are examined, with an eye on identifying potential program weaknesses that may need to be remedied to promote program efficiency, equity, and survival.Master of City and Regional Plannin

Selective attention and the visual representation of object attributes in the ventrolateral prefrontal cortex and anterior cingulate cortex of the rhesus monkey

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Brain and Cognitive Sciences, 2005.Includes bibliographical references (p. 52-56).The effects of attending to one or another of an object's attributes on neuronal representations of that object were investigated using extracellular recordings. A female rhesus monkey performed a delayed match to object attribute (DMSA) task, in which she alternately matched object orientations and object colors. In half of the task conditions, only one attribute matched the sample, forcing the animal to apply the current matching rule and ignore the irrelevant-attribute. Multiple simultaneous single-unit extracellular recordings were made in the ventrolateral prefrontal cortex (VLPFC) and anterior cingulate cortex (ACC) while the monkey performed the task. Neuronal selectivity for matching rule, object attributes, attribute relevance, response choice, and congruency were assessed using multi-factor ANOVAs. Attribute-selective responses were common in both cortical areas during the sample and delay periods, but were not significantly modulated by attribute relevance. There were few interactions between color-selective and orientation-selective responses according to the ANOVAs, suggesting that these attributes were represented independently.(cont.) Significant effects of attribute relevance, response choice, and congruency appeared in both areas after the delay period, when the probe appeared onscreen. VLPFC cells were more active during incongruent and non-match conditions, when responses had to be suppressed. ACC cells were more active during congruent and match conditions, when active response suppression was not required. The results indicate that although prefrontal cortex often shows a bias for relevant information (Rainer et al, 1998), it may not do so if the task requires frequent alternation of attentional sets or active suppression of conflicting responses. The data also indicate that the VLPFC's role in managing attentional 'set' (Banich et al, 2000; Milham et al, 2001) is performed in conjunction with active stimulus comparison and response selection (e.g., Rushworth et al, 1997), not during working memory maintenance. The ACC may facilitate the reactivation of response tendencies that had been actively suppressed, possibly as part of a larger role in managing response conflict (Botvinick et al, 2004).by Cynthia E. Kiddoo.Ph.D

Urethral overdilation for women with voiding dysfunction

AbstractObjectiveThis was a retrospective study of the efficacy of urethral overdilation (UOD) for women with voiding dysfunction.Materials and methodsThirty-six patients diagnosed with voiding dysfunction were enrolled. The main indications for UOD included women with poor compliance (30 patients, 83.3%) and obstructive symptoms with high residual urine (6 patients, 16.7%). We utilized a method called UOD (wide caliber), dilating the urethra up to 54 Fr. Patients were re-evaluated every 3 months with serial free flow rate and ultrasound residual in the first year and then as scheduled. Outcome measure was based on the change in videourodynamic parameters, Urogenital Distress Inventory-6 (UDI-6) questionnaire, and International Prostate Symptom Score (IPSS).ResultsMean follow up period of 33.2 months (range: 13–61 months). Failure or success depended on the change in videourodynamic parameters, UDI-6 score, and IPSS. The mean age with the Success Group (n = 22, 61.1%) and Failure Group (n = 14, 39.3%) was 52.8 years and 54.1 years, respectively. Our data showed significant improvements in mean UDI-6 score and IPSS after treatment (11.5–5.7, p = 0.032 and 14.8–5.2, p = 0.006, respectively). By analyzing multiple parameters (age, parity, body mass index, videourodynamics parameters, anesthesia bladder capacity, UDI-6 score, and IPSS) between the success and failure groups, we found only anesthesia bladder capacity reached statistical significance (536 mL vs. 418 mL, p = 0.005).ConclusionThe present study provides evidence that UOD, as a minimally invasive procedure, achieves a satisfactory cure rate on short-term follow-up for women with voiding dysfunction

Diurnal Variation in Urodynamics of Rat

In humans, the storage and voiding functions of the urinary bladder have a characteristic diurnal variation, with increased voiding during the day and urine storage during the night. However, in animal models, the daily functional differences in urodynamics have not been well-studied. The goal of this study was to identify key urodynamic parameters that vary between day and night. Rats were chronically instrumented with an intravesical catheter, and bladder pressure, voided volumes, and micturition frequency were measured by continuous filling cystometry during the light (inactive) or dark (active) phases of the circadian cycle. Cage activity was recorded by video during the experiment. We hypothesized that nocturnal rats entrained to a standard 12:12 light:dark cycle would show greater ambulatory activity and more frequent, smaller volume micturitions in the dark compared to the light. Rats studied during the light phase had a bladder capacity of 1.44±0.21 mL and voided every 8.2±1.2 min. Ambulatory activity was lower in the light phase, and rats slept during the recording period, awakening only to urinate. In contrast, rats studied during the dark were more active, had a lower bladder capacities (0.65±0.18 mL), and urinated more often (every 3.7±0.9 min). Average bladder pressures were not significantly different between the light and dark (13.40±2.49 and 12.19±2.85 mmHg, respectively). These results identify a day-night difference in bladder capacity and micturition frequency in chronically-instrumented nocturnal rodents that is phase-locked to the normal circadian locomotor activity rhythm of the animal. Furthermore, since it has generally been assumed that the daily hormonal regulation of renal function is a major driver of the circadian rhythm in urination, and few studies have addressed the involvement of the lower urinary tract, these results establish the bladder itself as a target for circadian regulation

Management of hydrocele in adolescent patients

Hydrocele is defined as an abnormal collection of serous fluid in the potential space between the parietal and visceral layers of the tunica vaginalis. In the majority of affected adolescents, hydrocele is acquired and is idiopathic in origin. The pathogenesis of idiopathic hydrocele is thought to be an imbalance in the normal process of fluid production and reabsorption. The diagnosis is usually clinical. Taking a thorough history is essential to rule out any fluctuation in size, which is an indication of a patent processus vaginalis. Scrotal ultrasonography is mandatory in nonpalpable testicles to rule out a subtending testicular solid mass requiring inguinal exploration. Otherwise, open hydrocelectomy via a scrotal incision is the standard treatment of idiopathic hydroceles. The second most common cause of hydrocele in adolescents is varicocelectomy. The risk of hydrocele formation is higher with non-artery-sparing procedures or those performed without microsurgical aid, and in surgery requiring cord dissection. If hydrocele occurs after varicocelectomy, initial management should include observation with or without hydrocele aspiration. Large persistent hydroceles are best served by open hydrocelectomy