Asian Shore Crab Population Decline at a Marsh Restoration Site in Stratford, Connecticut

Invasive species like Asian shore crabs (Hemigrapsus sanguineus) can disrupt coastal ecosystems, including restoration efforts. However, comparatively little attention has been given to the effects of restoring habitats on invasive H. sanguineus populations. This study estimated changes in H. sanguineus population size at a restored marsh site in Stratford, Connecticut from 2019 to 2022. Based on previous predation studies, we hypothesized that the H. sanguineuspopulation would decrease as the restored marsh matured. We conducted mark-recapture studies on H. sanguineus at Stratford Point each July in 2019, 2021, and 2022 and measured smooth cordgrass (Spartina alterniflora) density in 2019, 2020, and 2021. We used three common population size equations (Lincoln-Petersen index unmodified and with Bailey and Jolly-Seber modifications for resampling and non-closed populations) to calculate H. sanguineus population size in each year. The H. sanguineus population declined by 24 – 25% over the study period according to all three population size equations, supporting our hypothesis. Cordgrass density increased over the same time span. Since H. sanguineusoccurs mainly in areas with substantial cobble or rock and marshes encourage sediment deposition that can bury rocks, the maturing marsh may be a less suitable habitat for these crabs, reducing their population over time

Cost, Schedule and Safety Benefits of Early System Safety Involvement

System safety engineering is the application of engineering and management principles, criteria and techniques to achieve acceptable mishap risks. System safety typically reduces mishap risks through analyses that identify and address potential system failure modes. Studies indicate that when system safety is involved early in the product lifecycle, schedule slippage and cost escalation resulting from design changes can be substantially reduced. Development programs often face the dilemma of whether to apply funding to perform thorough, intensive system safety analyses in the conceptual design phase or wait until later, when designs are more complete, parts are being manufactured or testing is underway. Performing the analyses earlier consumes funds that might be needed later, while performing the analyses later increases the likelihood of expensive and time-consuming redesigns. This paper provides examples that encourage involving system safety engineering earlier in the process, by demonstrating the cost and schedule advantages, as well as the expected safety risk reduction. In addition, involving system safety earlier permits corrective actions to be implemented at a higher level in the system safety order of design precedence, which increases the effectiveness of corrective actions and reduces residual risk

A Water Pumping Photovoltaic Powered System Based on a Merged DC-DC Sepic-Cuk Converter

Trabalho apresentado em 2019 8th International Conference on Renewable Energy Research and Applications (ICRERA), 3-6 novembro 2019, Brasov, RomeniaThis paper has the purpose to present a non-isolated dual output DC-DC converter for a water pumping photovoltaic powered system. The proposed topology is based in the integration of a traditional Sepic and Cuk converters but requires only a single power semiconductor switch. It is characterized by an extension of the voltage static gain when compared with the classical boost topology and by a reduced voltage stress across the power switch and diodes. The system will be implemented through a classical MPPT algorithm that will control the proposed DC-DC converter. Several simulation and experimental results are also presented in order to confirm the characteristics of the proposed power converter and global water pumping systems.N/

Power Electronics Didactic Modules for Direct Current Machine Control

Several didactic modules for an electric machinery laboratory are presented. The modules are dedicated for DC machinery control and get their characteristic curves. The didactic modules have a front panel with power and signal connectors and can be configurable for any DC motor type. The three-phase bridge inverter proposed is one of the most popular topologies and is commercially available in power package modules. The control techniques and power drives were designed to satisfy static and dynamic performance of DC machines. Each power section is internally self-protected against misconnections and short-circuits. Isolated output signals of current and voltage measurements are also provided, adding versatility for use either in didactic or research applications. The implementation of such modules allowed experimental confirmation of the expected performance

Bidirectional Boost/Buck Quadratic Converter for Distributed Generation Systems with Electrochemical Storage Systems

Trabalho apresentado no 5th IEEE International Conference on Renewable Energy Research and Applications, 20-23 de novembro 2016, Birmingham, Reino UnidoThe increasing number of distributed generation systems using renewable and non-conventional energy sources show the trend of future generation systems. Most of these systems require power electronic converters as an interface between the DC voltage buses and electrochemical storage systems. Such storage systems, like batteries or supercapacitors, usually need bidirectional DC-DC converters to allow their charge or discharge according with necessary operation conditions. In this paper, a non-isolated bidirectional Buck-Boost converter with high voltage gain for electrochemical storage devices used in distributed generation systems is presented. To achieve high voltage gain ratios, the proposed topology presents quadratic characteristics in both step-down (Buck) and step-up (Boost) operation modes. In addition to the wide conversion range, it presents continuous input and output current, reduced charging/discharging ripple and simple control circuitry. All these features allow the energy exchange smoothly and continuously resulting in a longer durability of storage devices. The principle of the operation of the proposed converter in both operation modes, as well as their theoretical analysis will be discussed. The performance of this bidirectional power converter is confirmed through simulation and experimental results.N/

A Sensorless PMDC Motor Speed Controller with a Logical Overcurrent Protection

A method to control the speed or the torque of a permanent-magnet direct current motor is presented. The rotor speed and the external torque estimation are simultaneously provided by appropriate observers. The sensorless control scheme is based on current measurement and switching states of power devices. The observer’s performances are dependent on the accurate machine parameters knowledge. Sliding mode control approach was adopted for drive control, providing the suitable switching states to the chopper power devices. Despite the predictable chattering, a convenient first order switching function was considered enough to define the sliding surface and to correspond with the desired control specifications and drive performance. The experimental implementation was supported on a single dsPIC and the controller includes a logic overcurrent protection

A Partnership Between Nursing Faculty, Students, and Urban Community Centers to Provide Vision Screenings for Low-income Immigrant Women: An Experiential Case Study

Given the current health care climate, it is critical for nurse educators to provide learning opportunities for students to collaborate with leaders in the community to provide much-needed services to vulnerable populations. We developed, implemented, and evaluated a process for vision screenings and referrals to a local eye center for low-income, immigrant women over three years in an urban setting in the United States. This is a report on the program, including the challenges faced by the faculty and lessons learned by the nursing students

A metabolomics-based approach to study abiotic stress in Lolium perenne

In the United Kingdom and Ireland, a major percentage of fertilized agricultural area is devoted to grasslands, which helps to support the associated milk and beef production industries. In temperate grasslands, perennial ryegrass (L. perenne) is the major forage grass and this species is particularly suitable as a forage grass due to its high yield and digestibility, when compared with other species. However, perennial ryegrass is not well adapted to abiotic stress conditions which are likely to occur in its natural environment. Some of the abiotic stress factors which have significant impacts on plant growth and development include water and nutrient availability. Therefore, this project set out to unravel some of the mechanisms involved in the adaptation of perennial ryegrass to limited water, phosphorous and nitrogen. In order to understand the metabolic mechanisms acting in response to these stresses, metabolite profiling was performed using GC-MS. Furthermore, for the water- and phosphorous-limitation studies this approach was complemented with transcript analysis.In order to study water-limitation a hydroponics system supplemented with polyethyleneglycol (PEG) was used to induce water-limitation for a period of one-week. A clear difference in the metabolic profiles of the leaves of plants grown under water stress was observed. Differences were principally due to a reduction in fatty acid levels in the more water stress-susceptible genotype Cashel and an increase in sugars and compatible solutes in the drought-tolerant PI 462336 genotype. Sugars exhibiting a significant increase included, raffinose, trehalose, glucose, fructose and maltose. Raffinose was identified as the metabolite exhibiting the largest accumulation under water-stress in the more tolerant genotype and may represent a target for engineering superior drought tolerance or form the basis of marker-assisted breeding in perennial ryegrass. The metabolomics approach was combined with a transcriptomics approach in the water stress tolerant genotype PI 462336 which identified genes in perennial ryegrass that were regulated by this stress.The characterization of the response to phosphorus-limitation was performed in a hydroponics system containing two solutions with different levels of phosphorus. Samples were collected from the roots and leaves of two genotypes 24 hours after being exposed to stress. Internal phosphate concentrations were reduced and significant alterations were detected in the metabolome and transcriptome of two perennial ryegrass genotypes. Results indicated a replacement of phospholipids with sulfolipids in response to P deficiency and that this occurs at the very early stages of P deficiency in perennial ryegrass. Additionally, the results suggested the role of glycolytic bypasses and the re-allocation of carbohydrates in response to P deficiency The characterization of the metabolic response of L. perenne leaves to different levels of nitrogen supply was performed for seven different genotypes with variability in the regrowth response rate to nitrogen supply in a hydroponics system. This facilitated the identification of common mechanisms of response between genotypes to nitrogen. The metabolic response observed included modifications of the lipid metabolism, as well as alterations of secondary aromatic metabolite precursors in plants exposed to nitrogendeficit. In contrast, plants grown in a nitrogen saturated media appeared to modify to some extent the metabolism of ascorbate. Additionally, it was found that amino acid levels increased with increasing concentrations of nitrogen supplied. This study suggested that the involvement of secondary metabolism, together with lipid and ascorbate metabolism, is of crucial importance in the early-adaptation of perennial ryegrass plants to different levels of nitrogen supply.EThOS - Electronic Theses Online ServiceIrish Department of Agriculture, Fisheries and Food (DAFF) (RSF 06 346)GBUnited Kingdo

A SRM for a PV Powered Water Pumping System Based on a Multilevel Converter and DC/DC Dual Output Converter

Trabalho apresentado em 7th International Conference on Smart and Sustainable Technologies - Splitech 2022, 5-8 julho 2022, Bol, CroatiaThis paper focuses on a proposal for a system based on a photovoltaic (PV) supply for a powered water pumping. The system consists in a switched reluctance machine (SRM) controlled by a multilevel converter and fed by PV panels associated to a DC/DC converter. The multilevel power converter proposed to control the SRM was designed to minimize the switches and to support the balance of the two input capacitors. The DC/DC converter consists in a hybrid solution that merges a Buck- Boost converter with a Sepic converter. They use a topology solution in which the input current presents a reduced ripple and only requires one switch. This DC/DC converter is also characterized by a dual output to adapt to the multilevel converter. The control system and a maximum power point tracking (MPPT) algorithm are also presented. The operation of this system will be verified by tests that are done by computer simulations.N/