Complex permeability of soft magnetic ferrite polyester resin composites at frequencies above 1 MHz

Composite soft magnetic materials consist of magnetic particles in a non-magnetic matrix. The properties of such materials can be modelled using effective medium theory. Measurements have been made of the complex permeability of composites produced using ferrite powder and polyester resin. The success of various effective medium expressions in predicting the variation of complex permeability with composition has been assessed

WHO PAYS FOR RENEWABLES? THE EFFECT OF DATACENTRES ON RENEWABLE SUBSIDIES. ESRI Research Bulletin 2019/11

Ireland faces several targets for renewable energy usage, across the heating, transport and electricity sectors. These targets are set as a proportion of total energy usage. In the case of electricity, 40% of electricity must be generated from renewable sources by 2020. To meet this target, renewable electricity generation is subsidised through the Public Service Obligation levy, which appears on all consumers’ bills. The PSO is levied on residential consumers, commercial consumers and large industrial consumers according to their contribution to peak demand – the more the sector contributes to peak demand, the higher the portion of PSO that they pay

Investment vs. refurbishment: incentivising the correct quantity and quality of electricity generators. ESRI Research Bulletin 2016/2/1

Electricity markets are increasingly moving from a design wherein firms are compensated solely for the energy they provide (‘energy only’ markets) to one where firms are also compensated separately for other costs incurred. One example of a separate payment intended to compensate a firm for other costs incurred is a capacity remuneration mechanism (CRM). CRMs are designed to compensate firms for their fixed costs of capacity, or the cost of building the power plant. In this way, CRMs help to ensure that sufficient electricity generation capacity exists to provide sufficient generation during peak demand hours, ensuring reliable supply

Investment vs. Refurbishment: Examining Capacity Payment Mechanisms Using Mixed Complementarity Problems With Endogenous Probability. ESRI WP507. July 2015

Capacity remuneration mechanisms exist in many electricity markets. Capacity mechanism designs do not explicitly consider the effects of refurbishment of existing generation units in order to increase their reliability. This paper presents a mixed complementarity problem with endogenous probabilities to examine the impact of refurbishment on electricity prices and generation investment. Capacity payments are found to increase reliability when refurbishment is not possible, while capacity payments and reliability options yield similar results when refurbishment is possible. Final costs to consumers are similar under the two mechanisms with the exception of the initial case of overcapacity

Does tiny-scale atomic structure exist in the interstellar medium ?

We report on preliminary results from the recent multi-epoch neutral hydrogen absorption measurements toward three pulsars, B0823+26, B1133+16 and B2016+28, using the Arecibo telescope. We do not find significant variations in optical depth profiles over periods of 0.3 and 9--10 yr, or on spatial scales of 10--20 and 70--85 AU. The large number of non detections of the tiny scale atomic structure suggests that the AU-sized structure is not ubiquitous in the interstellar medium and could be quite a rare phenomenon.Comment: Accepted by ApJ Letters, 5 pages, 2 figure

A Menu Approach to Revealing Generator Reliability Using a Stochastic Bilevel Mathematical Program. ESRI WP518. November 2015

Liberalised electricity markets often include a capacity remuneration mechanism to allow generation firms recover their fixed costs. Various de-rating factors and/or penalties have been incorporated into such mechanisms in order to award the unit based on the contribution they make to system security, which in turn depends on the unit's reliability. However, this reliability is known to the firm but not to the regulator. We propose an adaptation of menu regulation to design capacity payments based on a declaration by the firm of their reliability. We scale payments and penalties according to this declared reliability such that the firm's profit-maximising strategy is to truthfully reveal their reliability. We apply the methodology to an illustrative test system. Truth-telling is induced, increasing the efficiency of capacity payments while eliminating the requirement for the regulator to allocate resources to discovering reliability

Challenges for Malaria Elimination in Zanzibar: Pyrethroid Resistance in Malaria Vectors and Poor Performance of Long-Lasting Insecticide Nets.

Long-lasting insecticide treated nets (LLINs) and indoor residual house spraying (IRS) are the main interventions for the control of malaria vectors in Zanzibar. The aim of the present study was to assess the susceptibility status of malaria vectors against the insecticides used for LLINs and IRS and to determine the durability and efficacy of LLINs on the island. Mosquitoes were sampled from Pemba and Unguja islands in 2010--2011 for use in WHO susceptibility tests. One hundred and fifty LLINs were collected from households on Unguja, their physical state was recorded and then tested for efficacy as well as total insecticide content. Species identification revealed that over 90% of the Anopheles gambiae complex was An. arabiensis with a small number of An. gambiae s.s. and An. merus being present. Susceptibility tests showed that An. arabiensis on Pemba was resistant to the pyrethroids used for LLINs and IRS. Mosquitoes from Unguja Island, however, were fully susceptible to all pyrethroids tested. A physical examination of 150 LLINs showed that two thirds were damaged after only three years in use. All used nets had a significantly lower (p < 0.001) mean permethrin concentration of 791.6 mg/m2 compared with 944.2 mg/m2 for new ones. Their efficacy decreased significantly against both susceptible An. gambiae s.s. colony mosquitoes and wild-type mosquitoes from Pemba after just six washes (p < 0.001). The sustainability of the gains achieved in malaria control in Zanzibar is seriously threatened by the resistance of malaria vectors to pyrethroids and the short-lived efficacy of LLINs. This study has revealed that even in relatively well-resourced and logistically manageable places like Zanzibar, malaria elimination is going to be difficult to achieve with the current control measures