Simulation and Efficiency Studies of Optical Photon Transportation and Detection with Plastic Antineutrino Detector Modules

In this work, the simulation of optical photons is carried out in an antineutrino detector module consisting of a plastic scintillator connected to light guides and photomultipliers on both ends, which is considered to be used for remote reactor monitoring in the field of nuclear safety. Using Monte Carlo (MC) based GEANT4 simulation, numerous parameters influencing the light collection and thereby the energy resolution of the antineutrino detector module are studied: e.g., degrees of scintillator surface roughness, reflector type, and its ap- plying method onto scintillator and light guide surface, the reflectivity of the reflector, light guide geometries and diameter of the photocathode. The impact of each parameter is inves- tigated by looking at the detected spectrum, i.e. the number photoelectrons per depositing energy. In addition, the average light collection efficiency of the detector module and its spatial variation are calculated for each simulation setup. According to the simulation re- sults, it is found that photocathode size, light guide shape, reflectivity of reflecting material and wrapping method show a significant impact on the light collection efficiency while scin- tillator surface polishing level and the choose of reflector type show relatively less impact. This study demonstrates that these parameters are very important in the design of plastic scintillator included antineutrino detectors to improve the energy resolution efficiency

Comparison of Plastic Antineutrino Detector Designs in the Context of Near Field Reactor Monitoring

We compare existing segmented plastic antineutrino detectors with our new geometrically improved design for antineutrino detection and light collection efficiency. The purpose of this study is to determine the most suitable design style for remote reactor monitoring in the context of nuclear safeguards. Using Monte Carlo based GEANT4 simulation package, we perform detector simulation based on two prominent experiments: Plastic antineutrino detector array (Panda) and Core monitoring by reactor antineutrino detector (Cormorad). In addition to these two well-known designs, another concept, the Panda2, can be obtained by making a small variation of Panda detector, is also considered in the simulation. The results show that the light collection efficiency of the Cormorad is substantially less with respect to the other two detectors while the highest antineutrino detection efficiency is achieved with the Cormorad and Panda2. Furthermore, as an alternative to these design choices, which are composed of an array of identical rectangular-shaped modules, we propose to combine regular hexagonal-shaped modules which minimizes the surface area of the whole detector and consequently reduces the number of optical readout channels considerably. With this approach, it is possible to obtain a detector configuration with a slightly higher detection efficiency with respect to the Panda design and a better energy resolution detector compared to the Cormorad design

Trade Shocks from BRIC to South Africa: A Global VAR Analysis

This paper studies the trade linkages between South Africa and the BRIC (Brazil, Russia, India, and China) countries. We apply a global vector autoregressive model (global VAR) to investigate the degree of trade linkages and shock transmission between South Africa and the BRIC countries over the period 1995Q1-2009Q4. The model contains 32 countries and has two different estimations: the first one consists of 24 countries and one region, with the 8 countries in the euroarea treated as a single economy; and the second estimation contains 20 countries and two regions, with the BRIC and the euro area countries respectively treated as a single economy. The results suggest that trade linkages exist between our focus economies; however the magnitude differs between countries. Shocks from each BRIC country are shown to have considerable impact on South African real imports and output.BRICS, Trade Linkages, Global VAR

A reactor antineutrino detector based on hexagonal scintillator bars

This study presents a new concept of segmented antineutrino detector based on hexagonal plastic scintillator bars for detecting antineutrinos from a nuclear reactor core. The choice of hexagonal scintillator bars is original and provides compactness. The proposed detector detects antineutrinos via inverse beta decay (IBD) with the prompt-delayed double coincidence. Owing to its segmented structure, the background, which satisfies the delayed coincidence condition can be eliminated by applying proper event selection cuts. In this manner, the main focus is to determine proper selection criteria to precisely tag the true IBD events. Monte-Carlo simulation is carried out to understand the characteristic of the IBD interaction in the proposed detector by using Geant4 toolkit. A set of event selection criteria is established based on the simulated data. It is found that a detection efficiency of 10 % can be achieved with the selection condition applied. It is also shown that fast neutrons, which constitute the main background source for above-ground detection, can be effectively eliminated with these selection criteria. The motivation for this study is to install this compact detector at a short distance (<100 m) from the Akkuyu Nuclear Power Plant, which is expected to start operation in 2023.Comment: 17 pages,13 figure

Alternative conducted immunity tests

Conducted immunity tests are always performed by the use of CDNs in laboratories in accordance with the standard EN61000-4-6. However, it is not always possible to use CDNs because of some limitations. If the EUT (Equipment Under Test) has large dimensions or high currents, it is not, most of the time, possible to send it to an EMC laboratory or to use CDNs during the test. As a consequence, usage of BCI probes is inevitable in industry. In this paper, we compared the laboratory setup installed with CDNs and alternative setups installed directly on mains without any CDNs in terms of loop impedances and injected loop currents. We also established a link based on the loop impedances and the injected currents on the test loops between the two setups. Finally, a first serious step was taken to establish the fundamentals of alternative conducted immunity tests based on the impedance measurements of test loops for industry.Postprint (published version

Modeling of temperature distribution in orthogonal cutting with dual-zone contact at rake face

In this study, an analytical model is developed in order to calculate the temperature distribution in orthogonal cutting with dual-zone contact at the rake face. The study focuses on heat generation at the primary shear zone and at the rake face. The material behavior at the primary shear zone is represented by Johnson-Cook constitutive equation whereas the contact at the rake face is modeled by sticking and sliding friction zones. This new temperature distribution model allows obtaining the maximum temperature at the rake face and helps determining two dimensional temperature distribution in the chip. The simulation results obtained from the developed model are also compared with experimental results where good agreement is observed

Medical hypothesis: can gonadotropins influence thyroid volume in women with PCOS?

It has been reported that luteinizing hormone (LH) had thyropropic effect on rat and human thyroid membrane. It has been known that patients with PCOS have elevated LH levels in comparison to healthy controls. The goiter prevalence is more common in women than in men regardless of population. The higher incidence of thyroid diseases in women has been previously attributed to higher estradiol levels. Estradiol has been shown to enhance proliferative and mitogenic activities of thyroid cells. However, in recent years chronic estradiol treatment has been shown to reduce volume densities of thyroid follicles, follicular epithelium and thyroid gland volume. It is thought to be due to LH suppression. Therefore we suggested that increased LH levels might provide a stimulus for growth on thyroid and alter thyroid function. Therefore patients with PCOS who had elevated LH levels should be treated by combined estradiol pills such as estrogen-progestin contraceptives for suppression of LH secretion. Further studies are needed to evaluate the association between LH, LH suppression and thyroid volume in patients with PCOS

CFD study on aerodynamic effects of a rear wing/spoiler on a passenger vehicle

Aerodynamic characteristics of a racing car are of significant interest in reducing car-racing accidents due to wind loading and in reducing the fuel consumption. At the present, modified car racing becomes more popular around the world. Sports cars are most commonly seen with spoilers, such as Ford Mustang, Subaru Impreza, and Chevrolet Corvette. Even though these vehicles typically have a more rigid chassis and a stiffer suspension to aid in high-speed maneuverability, a spoiler can still be beneficial. One of the design goals of a spoiler is to reduce drag and increase fuel efficiency. Many vehicles have a fairly steep downward angle going from the rear edge of the roof down to the trunk or tail of the car. Air flowing across the roof tumbles over this edge at higher speeds, causing flow separation. The flow of air becomes turbulent and a low pressure zone is created, thus increases drag. Adding a spoiler at the very rear of the vehicle makes the air slice longer, gentler slope from the roof to the spoiler, which helps to reduce the flow separation. Reducing flow separation decreases drag, which increases fuel economy; it also helps keep the rear window clear because the air flows smoothly through the rear window. The limitations of conventional wind tunnel experiment and rapid developments in computer hardware, considerable efforts have been invested in the last decade to study vehicle aerodynamics computationally. This thesis will present a numerical simulation of flow around racing car with spoiler positioned at the rear end using commercial fluid dynamic software ANSYS FLUENT®. The thesis will focus on CFD-based lift and drag prediction on the car body after the spoiler is mounted at the rear edge of the vehicle. A 3D computer model of 4-door sedan car (which will be designed with commercial software SolidWorks®) will be used as the base model. Different spoilers, in different locations will be positioned at the rear end of vehicle and the simulation will be run in order to determine the aerodynamic effects of spoiler

Effects of resins on mechanical performance of polymer concrete

Industrija cementa je danas odgovorna za najveće razine emisije ugljičnog dioksida (CO2) i potrošnje energije u građevinskoj industriji. Stoga je u današnje vrijeme primjena održivih vezivnih materijala kao zamjene za cement postalo pitanje od globalnog značenja. Iz prethodnih se radova vidi da su polimeri pouzdana i održiva alternativa cementu u graditeljstvu, a dugoročno gledano, polimerni betoni (PC) smatraju se najprikladnijom zamjenom tradicionalnih betona s cementom. U ovom se radu kao glavni cilj postavlja istraživanje utjecaja smola, koje se koriste kao vezivne komponente u polimernom betonu, na mehanička svojstva polimernih betona. U tom se smislu u radu analizira deset ortoftalnih nezasićenih poliesterskih smola (OUPR) koje se često koriste u građevinarstvu, te se provode ispitivanja svježeg i očvrsnulog betona u obliku ploča koje sadrže navedene smole. Nakon analize, svakom se tipu smole dodjeljuje indeks učinkovitosti. Eksperimentalni rezultati pokazuju da vrsta smole bitno utječe na mehanička svojstva polimernog betona.Cement manufacturing is currently responsible for one of the highest levels of carbon dioxide (CO2) emissions and energy consumption in construction industry. Thus, the use of sustainable binder materials instead of cement has become a worldwide issue. Previous studies have shown that polymers are a reliable and sustainable alternative to cement in construction, while polymer concretes (PCs) are seen as the biggest alternative to conventional cement concretes in the long term. In this study, the main objective is to investigate the effects of resins, which are used as binder components in polymer concrete, on the mechanical properties of the PCs. To achieve this, ten different orthophthalic unsaturated polyester resins (OUPR) that are commonly used in construction industry are considered, and fresh concrete tests and hardened concrete tests are performed on deck plates prepared with these resins. Based on the analysis results, each resin is given a performance index. The experimental results indicate that the type of resin has a significant impact on mechanical properties of polymer concrete