In this work the properties of thermoelectric modules (TEMs) and their behavior have been numerically modeled. Moreover, their applications very often require modeling not only of the TEM but also of ...the working environment and the product in which they will be working. A clear example is the fact that TEMs are very often installed with heat-dissipating elements such as fans, heat sinks, and heat exchangers; thus, the module will only work according to the heat dissipation conditions that these external sources can provide in a certain environment. In this context, analytic approaches, even though they have been proved to be useful, do not provide enough, accurate information in this regard. Therefore, numerical modeling has been identified as a powerful tool to improve detailed designs of thermoelectric solutions. This paper presents numerical simulations of a TEM in different working conditions, as well as with different commercial dissipation devices. The objective is to obtain the characteristic curve of a TEM using a valid numerical model that can be introduced into larger models of different applications. Also, the numerical model of the module and different cooling devices is provided. Both of them are compared against real tested modules, so that the deviation between them can be measured and discussed. Finally, the TEM is introduced into a manufacturing application and results are discussed to validate the model for further use.
This work presents the synthesis of all‐optical polymer dispersed liquid crystals (PDLC) devices, in which the reversible trans–cis photoisomerization of azobenzene groups is used to induce the ...transition in the liquid crystal (LC) phase, activating the film from an opaque to a translucent state. The appropriate morphology is obtained through a reaction‐induced phase separation strategy using an epoxy–amine matrix modified with azobenzene precursors and the addition of a thermoplastic polymer (polystyrene, PS), which promotes the phase separation and the preferential location of the LC in separated domains. Formulations with liquid crystal content of 50 wt%, 5 wt% of modifier (PS), and 10 wt% of azo‐precursor present a reversible on–off optical response when irradiating the sample with the activation beam at λ = 488 nm. It is demonstrated that the liquid crystal responds according to the expected cooperative movement of orientation with the azobenzene groups. Based on the study of the PDLC devices obtained, its potential technological application can be confirmed.
An all‐optical polymer dispersed liquid crystal (PDLC) device is prepared, triggering its response with azobenzene moieties activated by linearly polarized light. A reaction‐induced phase separation strategy is exploited to achieve the desired morphology. The liquid crystal responds to a cooperative orientation with the azobenzene groups. Based on the study of the devices obtained, its potential technological application can be confirmed.
Thermally reversible light scattering (TRLS) films were synthesized by the reaction-induced phase separation of solutions of N-4-ethoxybenzylidene-4‘-n-butylaniline (EBBA; 20−50 wt %) and polystyrene ...(PS; 1−5 wt %) in diglycidyl ether of bisphenol A (DGEBA), using benzyldimethylamine (BDMA) (0.06 mol with respect to epoxy groups), to initiate the polymerization. The material obtained after complete reaction consisted of a dispersion of EBBA/PS droplets in the epoxy network partially swollen by EBBA. The fractionation of EBBA between both phases was estimated using a simple thermodynamic model. Due to the matching of refractive indices of the three components, the multiphasic material was transparent above the nematic−isotropic transition temperature (T NI) of the EBBA/PS droplets. Below T NI the material exhibited a sharp transition to an opaque state due to the mismatching of refractive indices when EBBA was segregated as a nematic phase inside the droplets. The PS addition produced a significant decrease of the cloud-point conversion with respect to formulations devoid of PS. This led to relatively large domains that behave efficiently as light scattering centers in the PS-modified material, enabling high contrast ratios between transparent and opaque states to be obtained. The morphologies generated, and the corresponding optical properties of the TRLS films, did not change in the course of successive cooling/heating cycles.
Abstract This article reports world averages of measurements of b-hadron, c-hadron, and $$\tau $$ τ -lepton properties obtained by the Heavy Flavor Averaging Group using results available through ...summer 2016. For the averaging, common input parameters used in the various analyses are adjusted (rescaled) to common values, and known correlations are taken into account. The averages include branching fractions, lifetimes, neutral meson mixing parameters, $$C\!P$$ C P violation parameters, parameters of semileptonic decays, and Cabbibo–Kobayashi–Maskawa matrix elements.
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•Polymers containing azobenzene units and alkyl side chains were synthesized.•Azobenzene groups contribute to light response, alkyl chains form physical crosslinks.•Domains of alkyl ...chains are an alternative for optimizing photoinduced anisotropy.
The influence of physical crosslinks on the photoinduced anisotropy in epoxy linear polymers with azobenzene and alkyl side groups was studied. Two series of linear epoxy-based polymers were synthesized by reaction between diglycidyl ether of bisphenol A (DGEBA), Disperse Orange-3 (DO3), and dodecylamine (DA). Two strategies of synthesis were employed in order to analyse the optical behavior of the polymers with their architecture. As a result, a polymer with randomly distributed amine groups (one-step polymerization), and another with both amines forming blocks (two-step polymerization) were synthesized. The experimental evidence derived from different techniques confirmed that isothermal annealing at several temperatures produced association of DA alkyl chains. The rate of this physical gelation process could be varied with the annealing temperature and the polymer architecture. The association strength of the alkyl chains was higher for the block polymer. The rate of the physical gelation process increased as the annealing temperature did. UV–visible spectroscopy showed interactions between the azo groups and aggregated alkyl chains only for the polymer prepared in two steps. For the same chromophore content, block polymers yielded higher birefringence than random ones did. The increment in the information stored (remnant birefringence) for annealed samples was considerable only for block polymers. This study demonstrates the importance of the polymer architecture and the presence of domains of alkyl chains on its potential photo responsiveness.
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