Building Teacher Capacity to Support English Language Learners in Schools Receiving School Improvement Grants

The Study of School Turnaround examines the improvement process in a purposive sample of 35 case study schools receiving federal funds through the School Improvement Grants (SIG) program over a three-year period (2010 -- 11 to 2012 -- 13 school years). This brief focuses on 11 of these SIG schools with high proportions of English Language Learner (ELL) students (a median of 45 percent ELLs), describing their efforts to improve teachers' capacity for serving ELLs through staffing strategies and professional development (PD). Key findings that emerged from the ELL case study data collected during the 2011 -- 12 and 2012 -- 13 school years include:Few schools reported leveraging staffing strategies to improve teacher capacity for serving ELLs. Administrators in 3 of the 11 schools reported considering ELL expertise and experience when hiring classroom teachers, while respondents in 2 of the 11 schools reported that teachers' ELL expertise and experience purposefully factored into assignment of teachers to specific classrooms.Most teacher survey respondents (54 to 100 percent) in all 11 schools reported participating in ELL-related PD during the 2011 -- 12 school year. On average, teachers reported that ELL-related PD accounted for less than 20 percent of their total PD hours.Teacher survey respondents in schools that reported a greater PD focus on ELL-related topics, such as instructional strategies for advancing English proficiency or instructional strategies to use for ELLs within content classes, also generally appeared more likely to report that PD improved their effectiveness as teachers of ELLs

Integration Aspects of Full Converter Wind Turbines and the Impact on Long-term Voltage Stability

This paper examines how various integration aspects of full converter wind turbines, such as grid code design, control aspects, and placement of turbines, impact the long-term voltage stability of a power system. The simulations are conducted on a modified version of the Nordic32 test system. Different cases have been analyzed and show, for example, that if over-dimensioning of converters is implemented, it is mainly the converters’ currentcapacity that should be increased since the voltage limitation of converters seldom is reached during voltage instability events. Furthermore, a restrictive reactive control scheme is tested, with the aim of minimizing the wear and maintenance of converter components. Although found to generally reduce the voltage stability, the proposed control scheme could be adopted during specific conditions where the local need of voltage support is low. The placement of larger wind farms was found to have the largest impact, both on long-term voltage stability of the system itself, and on the effect that the analyzed design and control aspects had on the system stability. Consequently, the placement of WFs is found be an important factor to consider when designing ancillary services and grid codes for wind power

New Baryons in the Delta eta and Delta omega Channels

The decays of excited nonstrange baryons into the final states Delta eta and Delta omega are examined in a relativized quark pair creation model. The wavefunctions and parameters of the model are fixed by previous calculations of N pi and N pi pi, etc., decays through various quasi-two body channels including N eta and N omega. Our results show that the combination of thresholds just below the region of interest and the isospin selectivity of these channels should allow the discovery of several new baryons in such experiments.Comment: 10 pages, RevTe

A Congestion Forecast Framework for Distribution Systems with High Penetration of PV and PEVs

This paper presents a congestion forecast framework for electrical distribution systems with high penetration of solar photovoltaic and plug-in electric vehicles. The framework is based on probabilistic power flow to account for the uncertainties in photovoltaic production and load demand. The proposed framework has been implemented and tested using the data of the real distribution grid of Chalmers University of Technology campus. Cases studies have been carried out using the framework to analyse the impact of different local production levels and operating modes of solar photovoltaic inverter. The results have shown that cumulative probability for network congestion in branches and transformers would increase by 30% and 20% respectively, when the level of local PV generation, demand and PEVs demand to increase by 100%, 95% and 100% respectively. Also, results have shown that network congestion in branches and transformers is 4% and 8% respectively, more likely to occur in the constant-V mode as compared to constant-pf mode. These results can help distribution system operators to predict any upcoming congestion in their system and subsequently help them in taking suitable actions in order to mitigate congestion

The SIMPSONS project: An integrated Mars transportation system

In response to the Request for Proposal (RFP) for an integrated transportation system network for an advanced Martian base, Frontier Transportation Systems (FTS) presents the results of the SIMPSONS project (Systems Integration for Mars Planetary Surface Operations Networks). The following topics are included: the project background, vehicle design, future work, conclusions, management status, and cost breakdown. The project focuses solely on the surface-to-surface transportation at an advanced Martian base

Energy Scheduling Strategies for Grid-connected Microgrids: A Case Study on Chalmers Campus

This paper focuses on the optimal energy managementof grid-connected microgrids with battery energy storagesystems. The microgrid energy management and the optimalpower flow of the distribution network are formulated as mixed-integerlinear optimization problems to evaluate microgrid energyscheduling strategies including cost minimization, maximum useof own resources, and minimum energy exchange with theupstream network. The real distribution network of ChalmersUniversity of Technology campus is used as a case study. Thestudy results show that economic optimization yields an annualmicrogrid cost reduction of 4%. Alternatively, if the microgridminimizes the energy exchange, virtual islanding operation (zeroenergy exchange) for 3211 hours can be achieved within a year.The results also present the effects on the operation and costof the distribution system and highlight a trade-off betweenmicrogrid cost minimization and battery lifetime

Key Drivers and Future Scenarios of Local Energy and Flexibility Markets

This paper explores the key drivers of local energy and flexibility markets, develops a set of plausible future scenarios for these markets, and analyzes the scenarios\u27 impact. The results can provide insight to policymakers, researchers, system operators, and aggregators in a better design and more successful implementation of local markets. This study is based on the well-established scenario planning technique of "intuitive logics"and it is conducted by means of qualitative methods, surveys, and cross-impact analysis. Results explore and rank the impact and uncertainty of 20 key factors and trends which can affect the future of local energy and flexibility markets. The results show that factors related to the availability of active and smart end-users, and regulatory incentives are the most impactful and uncertain ones in the future of local markets. Four future scenarios are introduced based on these factors and their impacts are discussed

Transmission Line Protection Using Dynamic State Estimation and Advanced Sensors: Experimental Validation

This paper presents the experimental validation of a protection scheme for a transmission line based on dynamic state estimation along with the practical application of advanced sensors in this protection scheme. The scheme performs dynamic state estimation with high-frequency measurements provided by the sensors, assesses the operating condition (i.e., health) of the transmission line in real-time, and thereby determines the tripping signal whenever a fault is detected. The validation was carried out in two steps, first with simulation studies for a three-phase fault and then with the experimental implementation using a physical scaled-down model of a power system consisting of transmission lines, transformers, and loads. The simulation and validation results have shown that the scheme performs adequately in both normal and fault conditions. In the fault case with the experimental setup, the scheme could correctly detect the fault and send the trip signal to the line’s circuit breakers with a total fault clearing time of approximately 65 milliseconds which is comparable to conventional protection methods. The average processing time for a measurement sample block is 12.5 milliseconds. The results demonstrate that this scheme and the sensors would work for transmission line protection which can avoid relay coordination and settings issues

A Review on Challenges and Solutions in Microgrid Protection

Protection of microgrid has become challenging due to the hosting of various actors such as distributed generation, energy storage systems, information and communication technologies, etc. The main protection challenges in the microgrid are the bi-directional power flow, protection blinding, sympathetic tripping, change in short-circuit level due to different modes of operation, and limited fault current contribution by converter-interfaced sources. This paper presents a comprehensive review of the available microgrid protection schemes which are based on traditional protection principles and emerging techniques such as machine learning, data-mining, wavelet transform, etc. A categorical assessment of the reviewed protection schemes is also presented. The key findings of the paper suggest that the time-domain and communication-assisted protection schemes could be suitable solutions to address the identified protection challenges in the microgrid

Dynamic State Estimation based Transmission Line Protection Scheme: Performance Evaluation with Different Fault Types and Conditions

This paper presents the experimental validation of a transmission line protection scheme based on dynamic state estimation for different fault types and conditions. The protection scheme utilizes real-time high-frequency sampled measurements from advanced sensors and evaluates the operating condition of the transmission line based on which a tripping signal is generated in case a fault occurs. The validation is performed using a physical scaled-down model of a power system, consisting of a transmission line, transformer, synchronous generator, and loads. The following faults are examined during the validation: unbalanced faults under different load conditions, high impedance fault, fault current fed from both ends, hidden failure, external fault, and load change conditions. The results show that the scheme performs as intended and thus proves its efficacy to detect various types of faults. The maximum fault detection time is calculated to be 42.5 milliseconds, while the maximum fault clearing time comes out to be 82.5 milliseconds, on par with currently employed protection methods. The obtained results demonstrate the ability of the scheme to detect different fault types under varying conditions and avoid potential issues with relay coordinatio