Pitch Length Research Articles

Numerical Investigation on the Performance of Horizontal Helical-Coil-Type Backfill Heat Exchangers with Different Configurations in Mine Stopes

The application of ground heat exchanger technology in backfill mines can actualize subterranean heat storage, which is one of the most effective solutions for addressing solar energy faults such as intermittence and fluctuation. This paper provides a 3D unsteady heat transfer numerical model for full-size horizontal backfill heat exchangers (BFHEs) with five configurations in a mining layer of a metal mine by using a COMSOL environment. In order to ensure the fairness of the comparative analysis, the pipes of BFHEs studied have the same heat exchange surface area. By comparing and evaluating the heat storage/release characteristics of BFHEs in continuous operation for three years, it was discovered that the helical pipe with serpentine layout may effectively enhance the performance of BFHEs. Compared with the traditional SS BFHEs, the heat storage capacity of the S-FH type is significantly increased by 21.7%, followed by the SA-FH type, which is increased by 11.1%, while the performances of U-DH and SH type are considerably lowered. Also, the impact of the critical structural factors (pitch length and pitch diameter) was further studied using the normalized parameters C1 and C2 based on the inner diameter of the pipe. It is discovered that BFHEs should be distributed in a pipe with a lower C1, and increasing C2 encourages BFHEs to increase the storaged/released heat of BFHEs. By comparatively analysing the effect of thermal conductivity, it is found that the positive effects of thermal conductivity on the performance of SH, U-DH, SA-FH, and S-FH type BFHEs are found to decrease successively. This work proposes a strategy for improving the heat storage and release potential of BFHEs in terms of optimal pipe arrangement.

Heat transfer enhancement of serpentine channels with twisted tape insert by computational fluid dynamics and artificial intelligence

AbstractImproving the thermal–hydraulic performance of heat exchangers is a critical challenge. In this study, we investigated the impact of twisted tape insert geometrical variables, namely pitch length (P) and diameter (W), on the Nusselt number (Nu) and friction factor (f) within serpentine channels. To accomplish this, we employed computational fluid dynamics (CFD) as our simulation technique, with water as the working fluid. The validity of the CFD data was confirmed, leading to the development of artificial intelligence (AI) subsets: artificial neural network (ANN) and genetic algorithm (GA). In the prediction models, the following input variables were considered: Reynolds number (Re), (P/Dh), and (W/Dh). The ANN and GA models achieved a mean relative error (MRE) of 0.125% and 1.326% for Nu, and 0.139% and 4.104% for f, respectively. These results demonstrate the high accuracy of the correlations, with the ANN model showcasing superior performance.

Gender Role Attitudes Influence Vocal Masculine Preferences Among Gay Men in China.

Gender role attitudes refer to attitudes toward the appropriate roles, rights, and responsibilities of men and women in society. Evidence indicates that individuals with traditional gender role attitudes tend to prefer mates with sex-typical opposite-sex characteristics in heterosexual men and women. This study examined whether gender role attitudes were associated with vocal masculinity preference in gay men in China. Five hundred and sixty-seven participants aged between 16 and 49 years completed the vocal masculinity preference (voice pitch and vocal tract length; VTLs) and gender role attitudes scale. The results indicated that gay men generally preferred masculine voices (lower voice pitch and longer VTLs) and gender role attitudes were positively correlated with preferences for masculine cues in the voices of men. While individuals indicating an affinity with traditional gender roles exhibited stronger preferences for feminine voices, which were inconsistent with the present hypotheses. The results help us understand the role of traditional gender beliefs in the mate preferences of gay men in China. Furthermore, based on the results, understanding one's gender-role attitudes can help cultivate more diversified criteria for mate selection and facilitate gay men in better choosing suitable mates. Future longitudinal studies should examine the relationship between gender role attitudes and masculine preference changes over time. Whether this relationship differs in the different sexual roles of gay men should also be explored.

Influence of Propeller Parameters on the Aerodynamic Performance of Shrouded Coaxial Dual Rotors in Hover

A numerical method is used to evaluate the influence of propeller parameters on the aerodynamic performance of shrouded coaxial dual rotors in hover. Compared with the open-rotor configuration, the shrouded rotors reduce the tip vortex, resulting in a higher thrust and figure of merit (FoM). The varying inflow distribution over the inlet lip of the shroud introduces a different working condition for the propellers, thereby providing an opportunity for propeller parameter optimization. The pitch length, chord length, and tip clearance are chosen as the design parameters to improve the aerodynamic performance of the rotors. When the pitch lengths of the upper and lower propellers increase, the shrouded rotors outperform the original ones in both the coefficient of thrust (Ct) and in terms of the (FoM). The results show that increasing the chord length improves the Ct but that the (FoM) is almost unaffected. Moreover, smaller tip clearance can significantly improve the aerodynamic performance of the shrouded rotors. Results presented in this work provide insights into the parametric design and optimization of shrouded rotors.

Development and Validation of The Anadolu University Music Perception Test

In Turkey, children are accepted to conservatory music departments after fourth grade and fine arts high school music departments after eighth grade by taking a musical talent test. For students with high musical aural skills to know about their potential and be directed to the related education institutions there needs to be a valid test. This study was, therefore, conducted to develop a valid internet-based test to assess music perception of children with design-based research. Design-based research includes a series of iterative stages that involve continuous data collection, analysis, and improvement, rather than a linear process in development and implementation activities. Voluntary-basis selected schools in the pilot city’s first through fourth grades (both public and private schools) were invited to join the preliminary test. A total of 433 students participated in the online test. The test has seven categories including pitch discrimination (single, two, and multiple tones), tempo, length, melody, and rhythm. For item analysis, two separate sequential samples were collected. The results were evaluated according to psychometric test development principles. The initial results show that the music perception test (AMAT) is a valid and reliable instrument. The test is open to public use and can be reached at: https://aummat.anadolu.edu.tr/amat/

Discharge behavior of spherical and rock chip mucks by screw conveyors in TBM: Physical model experiments and DEM simulations

The discharge of muck through a screw conveyor system plays a crucial role in ensuring safe and cost-effective tunneling with earth pressure balance tunnel boring machines (EPB-TBM). However, the discharge mechanism of chip-type rocky mucks through a screw conveyor has not been well examined. Therefore, this study investigates the discharge behavior of rock chips through a screw conveyor by using a 3D discrete element model (DEM). Numerical simulations are conducted with rock chip particles of various sizes, as well as spherical particles, while varying the inclination angle, screw pitch length, and rotational speed of the screw conveyor. The simulation results show that the relative size between the muck particles and pitch has a significant effect on the discharge rate, and an optimal ratio of pitch to flight diameter is suggested. The particle-level analysis reveals distinctive particle discharge paths and a velocity distribution of muck particles along the screw axis. The study proposes the ratio of the screw pitch to the maximum particle size as the primary design parameter to predict the discharge rate. This is because large particles play a critical role in determining the discharge rate. The study highlights the usefulness of 3D DEM-based simulation as a tool to investigate discharge behavior of particulate materials through a screw conveyor. Moreover, it advances our understanding of rock chip-type muck discharge behavior during TBM excavation, providing guidance for screw conveyor design and feedback during TBM operation.

Optimizing Voice Recognition Informatic Robots for Effective Communication in Outpatient Settings.

Aim/Objective Within the dynamic healthcare technology landscape, this research aims to explore patient inquiries within outpatient clinics, elucidating the interplay between technology and healthcare intricacies. Building upon the initial intelligent guidance robot implementation shortcomings, this investigation seeks to enhance informatic robots with voice recognition technology. The objective is to analyze users' vocal patterns, discern age-associated vocal attributes, and facilitate age differentiation through subtle vocal nuances to enhance the efficacy of human-robot communication within outpatient clinical settings. Methods This investigation employs a multi-faceted approach. It leverages voice recognition technology to analyze users' vocal patterns. A diverse dataset of voice samples from various age groups was collected. Acoustic features encompassing pitch, formant frequencies, spectral characteristics, and vocal tract length are extracted from the audio samples. The Mel Filterbank and Mel-Frequency Cepstral Coefficients (MFCCs) are employed for speech and audio processing tasks alongside machine learning algorithms to assess and match vocal patterns to age-related traits. Results The research reveals compelling outcomes. The incorporation of voice recognition technology contributes to a significant improvement in human-robot communication within outpatient clinical settings. Through accurate analysis of vocal patterns and age-related traits, informatic robots can differentiate age through nuanced verbal cues. This augmentation leads to enhanced contextual understanding and tailored responses, significantly advancing the efficiency of patient interactions with the robots. Conclusion Integrating voice recognition technology into informatic robots presents a noteworthy advancement in outpatient clinic settings. By enabling age differentiation through vocal nuances, this augmentation enhances the precision and relevance of responses. The study contributes to the ongoing discourse on the dynamic evolution of healthcare technology, underscoring the complex synergy between technological progression and the intricate realities within healthcare infrastructure. As healthcare continues to metamorphose, the seamless integration of voice recognition technology marks a pivotal stride in optimizing human-robot communication and elevating patient care within outpatient settings.

Numerical investigation of entropy generation of turbulent flow in twisted tri-lobed tubes

Twisted tri-lobed tubes have garnered attention due to their exceptional heat transfer efficiency and straightforward fabrication. Existing literature lacks comprehensive assessments of the overall heat transfer performance of twisted tri-lobed tubes from the perspective of energy loss and irreversibility. This research aims to investigate entropy generation during turbulent water flow within twisted tri-lobed tubes, examining the influence of geometric parameters on local and average entropy production. Findings indicate that larger small circle radius (r) and straight lengths (l), coupled with smaller transition circle radius (R) and twist pitch lengths (p), result in diminished local and average heat transfer entropy production while enhancing local and average frictional entropy production, with heat transfer entropy generation dominating the overall entropy production. Additionally, with increasing Reynolds numbers, all twisted tubes demonstrate an increasing trend in average frictional entropy production, except for some cases (Case 1-Case 4) that exhibit an initial rise followed by a decline in average heat transfer entropy generation. Among the examined Reynolds range, Case 4 displays lower overall irreversibility compared to a plain tube. Following the second law of thermodynamics, Case 4 is preferred. The findings and methodology contribute to enhancing the thermodynamic evaluation of convective heat transfer in twisted tri-lobed tubes.

Comparative Experimental Study on Effect of Copper Wire Helical Wound Steel Tube with 2.5” Full Length Insert on Performance of Double Pipe Steel Tube Heat Exchanger

Abstract: A comparative experimental study was conducted to explore the hydrothermal behavior of a double tube heat exchanger with copper wire helical wound steel tubes and plane steel tubes with and without twisted tap inserts of pitch length 2.5 inches. In comparison to helical tubes, corrugated tubes, and many other more compact tube type heat exchangers, straight tube heat exchangers offer advantages since the construction of the heat exchanger tubes is easier. In the current work, the fluid-to-fluid heat exchange is considered, with a flow rate ranging from 15 to 75 liters/hour. Constant wall temperature or constant heat flux ideas are used in the majority of investigations on heat transfer coefficients. The efficiency, overall heat transfer coefficient, and impact of hot water flow rate with constant cold water flow rate for straight steel tube and copper wire helical wrapped steel tube heat exchangers in parallel flow and counter flow configurations were investigated and compared. Utilizing a 2.5" full length clockwise twisted tape insert, both layouts were created. The measurements were carried out in a constant state. When the hot water flow rate is increased while maintaining the cold water flow rate constant, the efficiency of the heat exchanger drops for both the straight steel and the copper wire helical wound steel tube. Compared to a plane steel tube heat exchanger, the copper wire helical wound steel tube heat exchanger has a better efficiency. The test findings demonstrate that inserting inserts causes pressure drop. With 2.5" clockwise twisted tape inserts wrapped in helical copper wire, steel tube was able to transmit heat more quickly than other arrangements.

Numerical Study on Thermo-Hydraulic Performance of Enhanced Tube With Crossed Helical Dimples

Abstract A numerical investigation was performed to study the thermo-hydraulic performance in an enhanced tube with crossed helical dimples. The simulations were carried out in the Reynolds number range of 5000–30,000 in crossed helical dimple tube of a period length with a constant wall temperature of 350 K. The thermal enhancement, friction factor, and performance evaluation criteria (PEC) were the primary focus of the present work. Moreover, geometric parameters such as spiral pitch, transverse length, and dimple depth were investigated for their effects on thermo-hydraulic performance. The results revealed that the shape of crossed helical dimple exerts positive effects on the heat transfer enhancement. This unique shape generated intensive transverse flow and induced a higher transverse velocity, leading to heat transfer enhancement. Therefore, the synthesized heat transfer performance was increased by 150–225% over that of the smooth tube. Furthermore, the heat transfer enhancement and friction factors increased with increasing dimple depth and declining spiral pitch and transverse length. Within the scope of this study, the maximum PEC = 2.25 was observed for Re = 30,000, P = 30 mm, L = 11.064 mm, and H = 3 mm.

Effect of light spectrum, salinity, and glucose levels on Spirulina morphology

AbstractThis study evaluated how light spectrum, salinity, and glucose level affect Spirulina morphology, using response surface methodology (RSM). A full factorial experiment was conducted including three light conditions with different predominant spectral characteristics (“white”: 100% white; “red”: 80% red, 15% blue, and 5% green; and “yellow”: 80% yellow, 15% blue, and 5% green), four NaCl concentrations (0, 5, 15, 30 g/L), and four glucose levels (0, 1.5, 2, 2.5 g/L). Light spectrum conditions and salinity had significant effects on the filament length, spiral diameter, and screw pitch length. Glucose only had a significant effect in terms of the spiral diameter. The maximum filament length (1274 μm; under 30 g/L NaCl and 2.5 g/L glucose), spiral diameter (47 μm; under 1 g/L NaCl and 2 g/L glucose), and screw pitch length (112 μm; under 1 g/L NaCl and 2 g/L glucose) were attained under yellow light. In line with the simulation, more compacted filaments, that is, with a greater diameter (41 μm) and shorter screw pitches (78 μm), are observed under “red” light (4 g/L NaCl and 2.5 g/L glucose). Because longer but compact filaments are desirable for easier harvesting, we recommend a light spectrum that is predominantly red with a NaCl concentration of 5.8 g/L deprived of glucose, for the cost‐effective harvesting of Spirulina biomass.

A Miniaturized Archimedean Screw Pump for High-Viscosity Fluid Pumping in Microfluidics.

Microfluidic devices have revolutionized the field of lab-on-a-chip by enabling precise manipulation of small fluid volumes for various biomedical applications. However, most existing microfluidic pumps struggle to handle high-viscosity fluids, limiting their applicability in certain areas that involve bioanalysis and on-chip sample processing. In this paper, the design and fabrication of a miniaturized Archimedean screw pump for pumping high-viscosity fluids within microfluidic channels are presented. The pump was 3D-printed and operated vertically, allowing for continuous and directional fluid pumping. The pump's capabilities were demonstrated by successfully pumping polyethylene glycol (PEG) solutions that are over 100 times more viscous than water using a basic mini-DC motor. Efficient fluid manipulation at low voltages was achieved by the pump, making it suitable for point-of-care and field applications. The flow rates of water were characterized, and the effect of different screw pitch lengths on the flow rate was investigated. Additionally, the pump's capacity for pumping high-viscosity fluids was demonstrated by testing it with PEG solutions of increasing viscosity. The microfluidic pump's simple fabrication and easy operation position it as a promising candidate for lab-on-a-chip applications involving high-viscosity fluids.

Design Analysis of a Helium Xenon-Printed Circuit Heat Exchanger for a Closed Brayton Cycle Microtransport Reactor

Microtransport with small size and a wide range of applications is very attractive for the utilization of future reactor modularization. A microreactor uses a closed Brayton cycle (CBC) to achieve high conversion efficiencies at low specific mass. The recuperator is one of the key components of CBC system which recovers heat exhausted from the turbine. A printed circuit heat exchanger (PCHE) is currently the preferred type of recuperator for the closed Brayton cycle due to its high heat transfer efficiency, high compactness, and high pressure and temperature resistance. This work intends to analyze different geometry configurations of a zigzag PCHE to increase its heat transfer efficiency while reducing its weight and size. The effect of geometric structure parameters such as channel diameter, zigzag pitch length, and zigzag angle on the Nusselt number and Fanning friction factor is investigated using a zigzag PCHE unit model. Based on the numerical simulation, the principle of least squares is employed to carry out a nonlinear fitting of the flow and heat transfer criterion correlation equations. Besides, the maximum value of the Nusselt number and minimum value of the Fanning friction factor are optimized as two conflicting objective functions using the nondominated sorting genetic algorithm-II (NSGA-II), with which a set of optimal solutions is obtained. Meanwhile, the shortest normalized distance is used to determine the compromised solution on the Pareto optimal points, and the independent variable’s sensitivity analysis is performed. Finally, a multiobjective optimization analysis is conducted for the PCHE to achieve lightweight and the high heat transfer efficiency design requirements of SIMONS.

Exploring the influence of task and environmental constraints on batting and bowling performance in cricket: A systematic review

Cricket is an unique international sport where environmental and task constraints have shown to have a significant impact on batting and bowling performance. The aim of this systematic review was to determine the effect of task and environmental constraints on cricket performance. A systematic literature search was conducted across Scopus, PubMed, Web of Science, CINAHL, and SportDiscus. Studies were deemed eligible if they reported the effects of pitch type, pitch length, equipment (e.g. cricket bat, batting pads, ball type, etc.) on cricket performance. A total of 20 studies met the inclusion criteria with Kmet score ranging between 75% and 92%. The results from this study demonstrate that environmental constraints such as pitch-type and task constraints such as equipment modification (e.g. type of cricket bat, batting pads, ball) and pitch length can influence cricketer's batting and bowling performance. Scaling cricket bats and reducing pitch length were acutely beneficial to cricket batting, while ball type, pitch length and soil properties were impactful on bowling performance. Importantly though, the impact of constraint manipulation seemed to be influenced by the skill level of the performer. The findings from this study may help to inform coaches and practitioners improve skill acquisition, through constraint manipulation, to develop highly adaptive cricket batting and bowling skill.

Analysis on enhanced turbulent heat transfer and flow characteristic in a twisted and dimpled oval tube

This work reveals the heat transfer and flow characteristic in a twisted and oval tube under turbulent flow and constant heat flux conditions. Numerical analyses were carried out on several twisted and oval tube configurations. In order to clearly reveal the effect of dimples in the swirl flow, the twisted oval tubes with and without dimples are considered. In order to enhance the convective heat transfer, the dimples were placed in the narrowing region of the twisted tube where the heat transfer was inefficient. The results indicate that the dimples on the twisted tube significantly increase the heat transfer, although they cause to slightly increase pressure drop penalty. While the decrease in the pitch length induced to enhance the heat transfer, it significantly and negatively affected the hydraulic performance of the tube. Furthermore, while the dimples on the twisted oval tube induce the average Nusselt number to increase by 14.8%, they cause to the friction factor increase by 18.0%. The best configuration that is the case of dimpled twisted oval tube having pitch length of 200 mm at Reynolds number of 10,000, yields thermo-hydraulic performance criteria of 1.428.

The effect of non-uniform pitch length and spiraling pathway on the mechanical properties of coiled carbon nanotubes

Coiled carbon nanotubes (CCNTs) exhibit exceptional mechanical, electrical, and thermal properties, making them suitable for diverse applications such as nanoelectromechanical devices. Here, classic molecular dynamics (MD) simulations were employed to investigate the coil morphology and the uniaxial tensile characteristics of thirteen CCNTs that were constructed by twisting carbon nanotube (CNT) segments of toroid formed by six identical CNT segments, with intricate effects of coil spacing and twist-induced spiraling pathway. The MD results showed that the coil morphology and stretching properties of CCNTs are greatly dictated by pitch length and spiraling pathway. All CCNTs showed unique characteristics of sawtooth-like patterns in the tensile stress-strain curves, originating from the separation of van der Waals (vdW) attracted coils, strain-induced buckling of CNT segments and nanohinge-like plastic deformations. Depending on the non-uniform pitch length and spiraling pathway of twisted CCNT segments, CCNTs exhibit different mechanical properties including Young's modulus, elastic limit, tensile strength, fracture strain, stiffness coefficient and distinguishing deformation mechanisms. Particularly, the fracture strain and tensile strength are significantly dictated by the pitch length and spiraling pathway, respectively. The elastic proprieties of finite element (FE) models scaled to CCNTs were established for comparison with the case of CCNTs with symmetrical spiraling. Moreover, CCNTs show high toughness that can be controlled by the pitch length and spiraling pathway. This study provides new insights and perspectives into the mechanical properties of nanocoils, which is of help to designing optimal nanocoils for nano-device systems.

Velocity Increment on Incidence Angle near the Leading Edge of the Compressor Cascade

The geometry of a compressor leading edge has an important effect on the aerodynamic performance at an off-designed incidence angle. The current geometric design methods of the leading edge are usually developed based on the flow characteristics at the designed incidence angle. However, few research focuses on the quantitative rules of the leading edge flow characteristics at the off-designed incidence angle in a compressor cascade. This situation restricts the further optimization and development of the leading edge geometry design method. In this paper, starting from the research of a potential cascade theory, the singularity point, where the surface velocity approaches infinity in the leading edge region, is eliminated by applying the characteristic that the ratio of the velocity increasement on the incidence angle in the plate cascade and the isolated plate flow is finite. Secondly, the equivalent pitch lengths based on 1/cos(β) and VI caused by a diffuser deceleration in the cascade passage were employed to correct the effect of the stagger angle. Finally, by introducing the isolated flow around the thick airfoil and considering the influence of the camber line geometry, a model of the variation of the surface velocity near the leading edge under the off-designed incidence angle, named the velocity increment on incidence angle, is derived from any compressor cascade. Hence, the relation between the off-designed incidence angle and the designed incidence angle of the surface velocity in a cascade blade is established, and it depends only on the geometrical parameters. Through a verification using numerical calculations and experimental measurement, the explicit formula for the velocity increment on incidence angle proposed in this paper has high precision near the leading edge.

Numerical study of reaction enhancement in hydrogen oxidation reactor with supercritical water medium by twisted oval structure

The oxidation of hydrogen in supercritical water supplies heat for the supercritical water gasification technology and is an essential part of the system. The mild release of heat in a limited space is a significant challenge. In the present study, a twisted oval structure was used to enhance the mixing inside the reactor, avoiding excessive local temperature and promoting heat transfer to the outside. A numerical model was developed to investigate hydrogen oxidation in supercritical H2O / CO2 mixtures. The effects of different inlet and structure parameters, including temperature, velocity, components, twisted pitch length, and aspect ratio, were evaluated. The steady-state simulation found that the circular structure allowed high-temperature fluids to cluster significantly around the nozzle and axis, resulting in excessive local temperatures. In contrast, the twisted oval structure stabilized the axial temperature faster while enabling more uniform temperature distribution in the radial direction. The maximum radial temperature difference and radial temperature variance were reduced by an average of 52.18% and 81.31%, respectively. Furthermore, the unreacted hydrogen escaping from the reactor at high flow rates was also avoided due to the enhanced radial mixing by the secondary flow in the twisted oval structure. The transient-state simulation showed that the twisted oval structure could stabilize the temperature distribution rapidly during reactor start-up, which might support further scale-up for the reactor.

Numerical simulation of the hydrodynamics in a novel jet loop bubble column with helical sieve tapes

Hydrodynamics and mixing in a novel down-flow jet loop reactor (DFJLR) with an internal helical sieve tape (HST) were studied by computational fluid dynamics (CFD) simulations. A helical sieve tape inside the draft tube caused a significant portion of the gas bubbles to flow helically, which increased radial mixing, overall gas holdup, axial liquid velocity, and turbulent kinetic energy. Compared with a similar reactor without a helical sieve tape, the gas holdup in reactors with a helical tape or a helical sieve tape inside the draft tube was increased, respectively, by 50 % and 75 %. A helical sieve tape with an area ratio of 27 % and helical pitch length of 492 mm was efficient in increasing gas holdup while keeping a lower pressure drop. Data and designs presented in this work will give insight and further understanding for reactor scale-up as a function of geometry and flow patterns for industrial applications.

Large Thermally Irreversible Photoinduced Shift of Selective Light Reflection in Hydrazone-Containing Cholesteric Polymer Systems.

Stimuli responsive liquid crystalline polymers are a unique class of so-called "smart" materials demonstrating various types of mesomorphic structures easily controlled by external fields, including light. In the present work we synthesized and studied a comb-shaped hydrazone-containing copolyacrylate exhibited cholesteric liquid crystalline properties with the pitch length of the helix being tuned under irradiation with light. In the cholesteric phase selective light reflection in the near IR spectral range (1650 nm) was measured and a large blue shift of the reflection peak from 1650 nm to 500 nm was found under blue light (428 or 457 nm) irradiation. This shift is related to the Z-E isomerization of photochromic hydrazone-containing groups and it is photochemically reversible. The improved and faster photo-optical response was found after copolymer doping with 10 wt % of low-molar-mass liquid crystal. It is noteworthy that both, the E and Z isomers of hydrazone photochromic group are thermally stable that enable to achieve a pure photoinduced switch without any dark relaxation at any temperatures. The large photoinduced shift of the selective light reflection, together with thermal bistability, makes such systems promising for applications in photonics.