Growth of 6Li-enriched LiCl/BaCl2 eutectic as a novel neutron scintillator

In this study, Eu:6LiCl/BaCl2 with a high Li concentration was developed as a novel thermal neutron scintillator. Eu ions were doped as activators for the BaCl2 phase, and Eu:6LiCl/BaCl2 eutectics were grown via the vertical Bridgman–Stockbarger method in quartz ampoules (inner diameter = 4 mm). The Eu:6LiCl/BaCl2 eutectic exhibited a lamellar eutectic structure and optical transparency. The 400-nm emission due to the Eu2+ 4f–5d transition was observed in the BaCl2 phase by a cathode luminescence measurement. The light yield under neutrons was estimated to be over 20,200 photons/MeV. A pulse shape discrimination study was also performed using gamma and alpha-rays. The Eu:6LiCl/BaCl2 eutectic scintillator showed good potential of pulse shape discrimination.

High Sensitivity Fiber Gas Pressure Sensor with Two Separated Fabry–Pérot Interferometers Based on the Vernier Effect

A high sensitivity optical fiber gas pressure sensor based on paralleled Fabry–Pérot interferometers (FPIs) was demonstrated. One micro-cavity FPI is used as a reference FPI (FPI-1) to generate a Vernier effect and the other FPI (FPI-2) is used as a sensing tip. Both FPIs are connected by a 3-dB coupler to form a paralleled structure. The FPI-1 was fabricated by fusion splicing a piece of hollow core fiber (HCF) between two sections of single-mode fibers (SMF), whereas FPI-2 was formed by fusion splicing a section of HCF between SMF and a piece of HCF with a slightly smaller inner diameter for sensing pressure. The gas pressure sensitivity was amplified from 4 nm/MPa of single FPI to 45.76 nm/MPa of paralleled FPIs with an amplification factor of 11.44 and a linearity of 99.9%. Compared with the traditional fiber gas pressure sensors, the proposed sensor showed great advantages in sensitivity, mechanical strength, cost, and temperature influence resistant, which has potential in adverse-circumstance gas pressure sensing.

Investigation of microflow reactor diameter on condensation reactions in L-proline-immobilized polymer monoliths

The effect of monolith structure and monolith reactor inner diameter on residence time distribution (RTD), and the relationship between RTD and the catalytic efficiency of the asymmetric aldol addition reaction...

Dual-band all-dielectric chiral photonic crystal

We present an all-dielectric chiral photonic crystal that guides the propagation of electromagnetic waves without backscattering for dual bands. The chiral photonic crystal unit cell is composed of four dielectric cylinders with increasing inner diameter clockwise or anticlockwise, which leads to chirality. It is demonstrated that the proposed chiral photonic crystal can generate dual band gaps in gigahertz frequency range and has two types of chiral edge states, which is similar to topologically protected edge states. Hence, the interface formed by the proposed two-dimensional (2D) chiral photonic crystal can guide the propagation of electromagnetic waves without backscattering, and this complete propagation is immune to defects (position disorder or frequency disorder). To illustrate the applicability of the findings in communication systems, we report a duplexer and a power divider based on the present all-dielectric chiral photonic crystal.

Establishment of the dependence of the strength indicator of the composite material of pressure hoses on the character of single damages

Experimental studies are presented and the dependence of the change in the strength of the material of a pressure head fire hose of type T with an inner diameter of 77 mm in the longitudinal direction is established, taking into account single damages. The work describes the plan of the experiment and carried out a number of field experiments to determine the effect of the length ld and the depth K damage on the strength F of the hose material, that is, obtaining the dependence F=f (ld, K). A mathematical method of experiment planning was used and a plan was drawn up for a complete multivariate experiment of type 2k with an acceptable model accuracy of 5 %. The limits of variation of the factors are set taking into account a priori information, experimental capabilities and on the basis of the results of preliminary search experiments. The dependence in the coded and natural values of the factors is obtained. The reliability of the relationship was checked using the Fisher test, the calculated value of which was 5.98, which confirms the adequacy of the described process with a probability of 95 %. Analyzing experimental studies of the dependence of the change in the strength of the hose material on the length and depth of damage, it can be said that the change in the strength of the hose almost linearly depends on the specified damage parameters. It is found that with increasing damage, the strength of the hose material significantly decreases. When varying the length factor and the greatest depth of damage, K=0.4 mm, the strength of the hose material decreases from 11.67 kN to 8.77 kN, and in percentage terms by 25 %. The results obtained can be used in practical units of emergency rescue teams, when diagnosing hidden damage in pressure head fire hoses in order to prevent their failure in case of fires

Experimental Investigation of the Heat Transfer and Pressure Drop inside Tubes and the Shell of a Minichannel Shell and Tube Type Heat Exchanger

This paper presents an experimental study on a shell and tube mini heat exchanger (STMHE). The STMHE consisted of seven tubes in a triangular arrangement, with an 0.8 mm inner diameter and 1.0 mm outer diameter. The heat exchanger shell had an inner diameter of 11 mm, and the heat exchanger had no baffles. For the adopted operating conditions, the Reynolds number on the tube side varied in the range of 300–3000, and 2000–12,000 on the shell side. The aim of this study was to determine pressure drop values during fluid flow and Nusselt number correlations for the heat transfer. A new method based on optimisation was used to derive the equations for calculating the heat transfer coefficients. It allowed the determine of the correlation equations for the heat transfer coefficients simultaneously for both sides of the heat exchanger. The obtained correlations yielded overall heat transfer coefficient values that, in most cases, did not differ by more than from those determined experimentally. The experimentally determined critical Reynolds number value for the flow inside the tubes was equal to . The Darcy friction factors correlated well with the classical laminar flow correlation and with the Blasius correlation for turbulent flow. The derived correlations for the Nusselt number were best aligned with the Sieder–Tate, Gnielinski, and Kozioł correlations for tube side laminar flow, turbulent flow, and shell flow, respectively. Good agreement between the results obtained using the experimentally derived correlations and the correlations available in the literature confirms the effectiveness of the used optimisation–based method.

A Miniature Fabry–Pérot Fiber Interference Sensor Based on Polyvinyl Chloride Membrane for Acoustic Pressure Sensing in Mid–High-Frequency Band

In this paper, a Fabry–Pérot interference fiber sensor was fabricated by using a Polyvinyl chloride membrane (20 μm in thickness) attached at the end of a ferrule with an inner diameter of 1.1 mm. In consideration of the vibration response of the membrane, the feature of the first-order natural frequency of membrane was analyzed by COMSOL Multiphysics. The acoustic sensing performance of the Fabry–Pérot fiber interference sensor was studied in air. The results reveal that the sensor possessed good acoustic pressure sensitivity, in the order of 33.26 mV/Pa. In addition, the noise-limited minimum detectable pressure level was determined to be 58.9 μPa/Hz1/2 and the pressure-induced deflection obtained was 105 nm/Pa at the frequency of 1 kHz. The response of the sensor was approximately consistent with the reference sensor from 1 to 7 kHz. All these results support that the fabricated Fabry–Pérot fiber interference sensor may be applied for ultra-sensitive pressure sensing applications.

Evaluation of Pressure Drop of Two-Phase Flow Boiling with R290 in Horizontal Mini Channel

Various experiments on the pressure drop of a two-phase flow boiling in a mini channel tube have been carried out. This study is aimed at characteristics of the pressure drop of a two-phase flow boiling using a refrigerant R290. The experiment uses a horizontal, stainless steel, 2-m-long mini-channel tube with a 3-mm inner diameter. The experiment has been carried out using various data with the vapor qualities ranging from 0.1 to 0.9, the mass fluxes ranging 50 kg/m2s to 180 kg/m2s, and the heat fluxes ranging from 5 kW/m2 to 20 kW/m2. Furthermore, several homogeneous and separated methods were used to predict the experimental data. Li and Hibiki’s correlation give the best overall deviation pressure drop value is the most accurate with its deviation amounting 19.47%.

Preparation of Metal-Immobilized Methacrylate-Based Monolithic Columns for Flow-Through Cross-Coupling Reactions

With the aim of developing efficient flow-through microreactors for high-throughput organic synthesis, in this work, microreactors were fabricated by chemically immobilizing palladium-, nickel-, iron-, and copper-based catalysts onto ligand-modified poly(glycidyl methacrylate-co-ethylene dimethacrylate) [poly(GMA-co-EDMA)] monoliths, which were prepared inside a silicosteel tubing (10 cm long with an inner diameter of 1.0 mm) and modified with several ligands including 5-amino-1,10-phenanthroline (APHEN), iminodiacetic acid (IDA), and iminodimethyl phosphonic acid (IDP). The performance of the resulting microreactors in Suzuki−Miyaura cross-coupling reactions was evaluated, finding that the poly(GMA-co-EDMA) monolith chemically modified with 5-amino-1,10-phenanthroline as a binding site for the palladium catalyst provided an excellent flow-through performance, enabling highly efficient and rapid reactions with high product yields. Moreover, this monolithic microreactor maintained its good activity and efficiency during prolonged use.