W UMa type binaries have two defining characteristics. These are (i) the effective temperatures of both components are very similar, and (ii) the secondary (currently less massive) component is ...overluminous for its current mass. We consider the latter to be an indication of its mass before the mass transfer event. For these stars, we define a mass difference (δM) between the mass determined from its luminosity and the present mass determined from fitting the binary orbit. We compare the observed values of the mass difference to stellar models with mass-loss. The range of initial secondary masses that we find for observed W UMa type binaries is 1.3-2.6 M. We discover that the A- and the W-subtype contact binaries have different ranges of initial secondary masses. Binary systems with an initial mass higher than 1.8 ± 0.1 M become A-subtype while systems with initial masses lower than this become W-subtype. Only 6 per cent of systems violate this behaviour. We also obtain the initial masses of the primaries using the following constraint for the reciprocal of the initial mass ratio: 0 < 1/q
i < 1. The range of initial masses we find for the primaries is 0.2-1.5 M, except for two systems. Finally in comparing our models to observed systems, we find evidence that the mass transfer process is not conservative. We find that only 34 per cent of the mass from the secondary is transferred to the primary. The remainder is lost from the system.
Residential architecture constitutes one of the largest market segments in the construction sector. However, the attention that it is given in the field of daylight performance simulation is ...surprisingly low. This poses the question of whether existing daylighting metrics are well suited for residential design. Findings from 79 references are summarized, and a critical review of current climate-based daylighting metrics in the context of residential architecture is provided. It is found that existing workflows often overlook relevant aspects of daylight in residential spaces, such as diurnal and seasonal availability of daylight and access to direct sunlight. Hence, a concept for a new climate-based, annual evaluation framework that overcomes these shortcomings, called the residential daylight score, is introduced.
Various emerging technologies encourage the embedding of intelligent and climate responsive behaviour into architectural elements. Light-shelves have been used for decades to enhance natural light in ...spaces, however, their static nature is limiting their overall performance potential. This paper explores the convergence of rapid prototyping, parametric design and environmental modelling software to create a dynamic and direct-reflection daylight redirection system that significantly enhances daylight availability. A Radiance-based simulation workflow to optimise and study the system is used and a 1:1 mock-up is developed. The mock-up is based on a horizontal-light shelf with an array of mirror tiles that can tilt in two axes based on sun position. The potential impact of such a system is then evaluated for a side lit office space in multiple climates in the northern hemisphere. Results show that daylight can be redirected deep into the building more effectively and therefore improve daylight availability for otherwise underlit floor plan regions. Projected savings for electric lighting range from 17% to 35% compared with a static redirection system.
Evaluation metrics using climate-based daylight modelling paradigms have become the de-facto standard in work environments but have only limited applicability in residential architecture. Qualities ...of daylight cited in the architectural design literature, such as daily and seasonal availability of daylight as well as access to direct sunlight, are simulated in detail but are usually overlooked in the commonly used evaluation metrics. In a recent paper, a new climate-based, annual daylight evaluation framework called the residential daylight score has been proposed for cold and temperate climates. It assesses daylight autonomy and access to direct light in 12 daily and seasonal bins and proposes targets for seasonal and diurnal daylight autonomy and duration of direct sunlight exposure. While the metric aims to capture essential characteristics of residential daylight, only a few reference cases exist in the literature to adequately judge its achievability and applicability. This paper aims to thoroughly test the residential daylight score and provide reference cases for 2444 apartments from a set of 18 multifamily buildings that compare the new metric with currently used climate-based metrics.
Magnesium orthosilicate (Mg2SiO4) was synthesized via a traditional solid-state reaction and a wet chemical route. This study primarily reported the thermoluminescence (TL) behavior of Mg2SiO4 host. ...X-ray diffraction pattern revealed that Mg2SiO4 exhibits orthorhombic structure matched with JCPDS card 900-6398. Dose response, reproducibility and trap parameters of TL glow curves were evaluated to clearly reveal TL features. Two TL glow peaks situated at 81 °C and 192 °C were monitored at a heating rate of 2 °Cs−1. We observed anomalous heating rate effect for the peak centered at 192 °C whilst TL intensity of the peak at 81 °C decreases with elevating heating rate. Trap depths of the electrons within the trap centers were found to be 1.04 ± 0.01eV and 1.37 ± 0.01eV for both methods using peak shape (PS) method. Distribution of trap centers was examined using the Tmax−Tstop method and this case indicated that the glow curves consist of single TL peaks. The intensity of TL glow curves exhibited a good linear dose response under total area up to 20 Gy. A comparison of the two preparation techniques revealed that TL characteristics of this phosphor are partly dependent and Mg2SiO4 could be a promising material for dosimetric application.
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•Mg2SiO4 phosphors synthesized by a solid-state reaction and wet chemical processes.•TL glow curve recorded under beta excitation.•TL glow curve contains dual peak at 81 °C and 193 °C.•Anomalous heating rate was observed.•Phosphor exhibits dosimetric TL glow peak.
To evaluate the dopant effect precisely, X-ray diffraction (XRD) for structural, scanning electron microscopy (SEM) with energy dispersive x-ray spectroscopy (EDS) analysis for morphological, ...photoluminescence (PL) and thermoluminescence (TL) characteristics of un-doped, 2.0 mol% Sm3+ doped and 2.0 mol% Sm3+;x mol% Mn2+ (x = 0.5, 1.0, 2.0, 4.0) doped Zn2SiO4 phosphors were tested. PL mechanisms of excitation and emission were discussed together with data on the structure and morphology of the samples. The beta doses from 0.1 to 500 Gy with various steps were applied to observe the glow curve readouts after 200 °C preheat at a linear heating rate of 2 °C/s from RT to 500 °C. Zn2SiO4:2.0%Sm3+;0.5%Mn2+ was chosen for further analysis due to having both the most PL and TL peak area. Various heating rate method was used to determine the kinetic parameters as well as initial rise with TM-Tstop analysis and computerized glow curve deconvolution methods.
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•Zn2SiO4:Sm3+;Mn2+ nanocrystalline phosphor was synthetized by gel combustion method.•Crystal structure and morphology were evaluated by XRD, SEM and EDS analyses.•Luminescence properties were discussed using PL and TL methods.•Overlapped TL peaks behavior were evaluated using IR (with TM - Tstop analysis) and CGCD methods.•The causes of the decrease in the activation energy with increasing temperature were physically explained.
In this study, we have synthesized B doped Ca5(PO4)3OH (HAP) by a sonication chemical method. The thermoluminescence (TL) properties of the family of synthesized samples (B doped Ca5(PO4)3OH (HAP) ...were investigated using an IRSL-TL 565 nm filter. This gave the highest TL intensity of each phosphor after 2 Gy β-irradiation. Three TL glow peaks of B doped Ca5(PO4)3OH (HAP) are centered at around 84, 208 and 324 °C (with a heating rate of 2 °Cs-1). The trapping parameters such as activation energy (E), order of kinetics (b), frequency factor (s) were calculated by using initial rise (IR), various heating rates (VHR) and computerized glow curve deconvolution (CGCD) method. The response of TL glow curves remained constant within ±5% deviation from the initial value after 9 cycles of reuse; but only at tenth cycle the deviation goes up to 6%.
•Ca5(PO4)3OH:B sample is synthesized by a sonication chemical method.•Thermoluminescence properties were conducted.•Activation energies were calculated using IR, Booth-Bohun-Parfianovitch and CGCD methods.•The influences of concentration quenching and temperature lag on the glow curves were discussed.
•ZnB2O4:Sm3+ phosphors were synthesized by low temperature chemical synthesis method.•The Thermoluminescence properties were studied by beta excitation source.•Trapping parameters were determined ...using different methods.
This study is mainly centered on thermoluminescence (TL) behavior under beta excitation at room temperature (RT) of Sm3+ activated ZnB2O4 phosphors synthesized by low temperature chemical synthesis method. The prepared phosphors were characterized by the X-ray powder diffraction (XRD) method. The effects of dopant concentration, beta radiation dose (0.115–69 Gy) and heating rate (0.5–10 °C/s) on TL intensity of Sm3+ doped ZnB2O4 phosphors and reproducibility are investigated using a lexsyg smart TL/OSL reader system. The activation energy values, E obtained from the analysis of the TL glow curve were calculated with initial rise (IR) method and peak shape (PS) method over the deconvoluted glow curves. The Ea–Tstop and CGCD methods indicated that the glow curve of this phosphor is the superposition of at least six components, which were called to as P1–P6, in the temperature range between RT and 400 °C. The results reveal that 2% Sm3+ doped ZnB2O4 gives optimum TL response, the relative intensity of the glow peak increases linearly with increase of beta dose and, the peaks of TL glow curves shift towards the higher temperature side with increase in heating rate as the total area under the glow peak remains the same. The maximum variation of reproducibility for ten successive irradiation cycles of 20.7 Gy is less than 3% from the average value and the sample doped 2% Sm3+ shows a good stability for the reusability. Additionally, the results obtained from IR and PS methods indicates that the complex glow curve is composed of six distinguishable peaks.
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