Battery energy management strategies for UK firm frequency response services and energy arbitrage

Due to the increasing renewable penetration, there is potential for larger and faster grid frequency fluctuations increasing the risk of system instability. The National Grid Electricity Transmission, primary electricity transmission network operator in the UK, has introduced various frequency response services that are developed to provide a real-time response to deviations in the grid frequency. A battery energy storage system is a suitable choice for delivering such services. Here, a control algorithm is presented which generates a charge/discharge power output with respect to deviations in the grid frequency and the required specifications. Using the real UK electricity prices, an arbitrage control algorithm has been also developed to deliver different types of grid balancing services, while scheduling throughout the day for energy arbitrage. Simulation results show that the proposed algorithm delivers both dynamic and non-dynamic firm frequency response and also enhanced frequency response to specifications, while generating arbitrage revenue in the balancing market. Simulation results on a 1 MW/1 MWh lithium-titanate BESS are provided to verify the proposed algorithm based on the control of an experimentally validated battery model

Use of an orthovoltage X-ray treatment unit as a radiation research system in a small-animal cancer model

<p>Abstract</p> <p>Background</p> <p>We explore the use of a clinical orthovoltage X-ray treatment unit as a small-animal radiation therapy system in a tumoral model of cervical cancer.</p> <p>Methods</p> <p>Nude mice were subcutaneously inoculated with 5 × 10⁶HeLa cells in both lower limbs. When tumor volume approximated 200 mm³treatment was initiated. Animals received four 2 mg/kg intraperitoneal cycles (1/week) of cisplatin and/or 6.25 mg/kg of gemcitabine, concomitant with radiotherapy. Tumors were exposed to 2.5 Gy/day nominal surface doses (20 days) of 150 kV X-rays. Lead collimators with circular apertures (0.5 to 1.5 cm diameter) were manufactured and mounted on the applicator cone to restrict the X-ray beam onto tumors. X-ray penetration and conformality were evaluated by measuring dose at the surface and behind the tumor lobe by using HS GafChromic film. Relative changes in tumor volume (RTV) and a clonogenic assay were used to evaluate the therapeutic response of the tumor, and relative weight loss was used to assess toxicity of the treatments.</p> <p>Results</p> <p>No measurable dose was delivered outside of the collimator apertures. The analysis suggests that dose inhomogeneities in the tumor reach up to ± 11.5% around the mean tumor dose value, which was estimated as 2.2 Gy/day. Evaluation of the RTV showed a significant reduction of the tumor volume as consequence of the chemoradiotherapy treatment; results also show that toxicity was well tolerated by the animals.</p> <p>Conclusion</p> <p>Results and procedures described in the present work have shown the usefulness and convenience of the orthovoltage X-ray system for animal model radiotherapy protocols.</p

Improving collection flows in a public postal network with contractor's obligation considerations

We examine a problem that arises in the postal industry of developing goods collection routes that are subjected to a bidding process where the price is positively correlated to routes operating complexities. The route complexity would delay the arrival of goods to distribution centers and prevent their deliveries to processing plants within the required time windows. We formulate the problem as a variant of the multiple depot vehicle routing problem with time windows. The ant colony optimization algorithm is discussed as a solution methodology and evaluated in a case study that involves a real-life problem faced by a public postal service organization

Effects of Sowing Date and Plant Density on Yield and Yield Components of Grass Pea (Lathyrus sativus L.) in Birjand Region

Grass pea (Lathyrus sativus L.) is a crop which could substitute soybean in poultry ration in arid and semi-arid regions. To investigate the effects of sowing date and plant density on yield and yield components of grass pea, a factorial experiment based on randomized complete blocks design with four replications was conducted at Research Farm of Faculty of Agriculture, University of Birjand in 2008. Treatments included three sowing dates (March 5, March 21 and April 4) and four plant densities (30, 40, 50 and 60 plants per m2). Number of pods per plant, number of seeds per pod, number of seeds per plant, 100-seed weight, seed yield, biological yield and harvest index were measured. Results showed that by delaying the planting date, number of pods per plant, number of seeds per plant, seed yield and biological yield were decreased significantly. Maximum seed yield (2524 kg/ha) was achieved at the early sowing date (5th of March). These traits were increased with increasing plant density up to 50 plants per m2. But, increasing the plant density to 60 plants per m2 caused a decrease of these characteristics. Different planting dates and densities did not show any significant changes in number of seeds per pod, 100-seed weight and harvest index. Based on these results and the fact that Birjand is overwhelmed by an arid climate, planting grass pea at the first possible date at the end of winter with a moderate planting density (50 plants per m2) can lead to a reasonable seed yield

Improved spatial resolution by MOSFET dosimetry of an x-ray microbeam

Measurement of the lateral profile of the dose distribution across a narrow x-ray microbeam requires a dosimeter with a micron resolution. We investigated the use of a MOSFET dosimeter in an ‘‘edge-on’’ orientation with the gate insulating oxide layer parallel to the direction of the beam. We compared results using this technique to Gafchromic film measurements of a 200 micrometer wide planar x-ray microbeam. The microbeam was obtained by using a vernier micrometerdriven miniature collimator attached to a Therapax DXT300 x-ray machine operated at 100 kVp . The ‘‘edge-on’’ application allows utilization of the ultra thin sensitive volume of the MOSFET detector. Spatial resolution of both the MOSFET and Gafchromic film dosimeters appeared to be of about 1 micrometer. The MOSFET dosimeter appeared to provide more uniform dose profiles with the advantage of on-line measurements